WO2022237307A1 - 电动工具及其控制方法 - Google Patents

电动工具及其控制方法 Download PDF

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Publication number
WO2022237307A1
WO2022237307A1 PCT/CN2022/081177 CN2022081177W WO2022237307A1 WO 2022237307 A1 WO2022237307 A1 WO 2022237307A1 CN 2022081177 W CN2022081177 W CN 2022081177W WO 2022237307 A1 WO2022237307 A1 WO 2022237307A1
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WO
WIPO (PCT)
Prior art keywords
current
motor
power tool
control module
tool according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2022/081177
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English (en)
French (fr)
Inventor
朱宏
王鹏臣
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nanjing Chervon Industry Co Ltd
Original Assignee
Nanjing Chervon Industry Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN202110518929.3A external-priority patent/CN115940747A/zh
Priority claimed from CN202110519047.9A external-priority patent/CN115967331A/zh
Priority claimed from CN202110525390.4A external-priority patent/CN115347820B/zh
Priority claimed from CN202111036354.8A external-priority patent/CN115776094A/zh
Application filed by Nanjing Chervon Industry Co Ltd filed Critical Nanjing Chervon Industry Co Ltd
Priority to EP22806282.4A priority Critical patent/EP4311101B1/en
Publication of WO2022237307A1 publication Critical patent/WO2022237307A1/zh
Priority to US18/489,371 priority patent/US20240072715A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/02—Providing protection against overload without automatic interruption of supply
    • H02P29/024—Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load
    • H02P29/027—Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load the fault being an over-current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/28—Arrangements for controlling current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/0833—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors for electric motors with control arrangements
    • H02H7/0838—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors for electric motors with control arrangements with H-bridge circuit
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using DC to AC converters or inverters
    • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using DC to AC converters or inverters with pulse width modulation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for

Definitions

  • the present application relates to an electric tool, in particular to a control method suitable for an AC electric tool.
  • AC power tools especially for high-voltage brushless tools, are prone to overcurrent due to the large enough power supply capacity of the power grid, which not only easily damages electronic components, but also significantly affects the power tools to a large extent. use feel.
  • the present application provides a current limiting control method suitable for AC power tools, which can effectively suppress large currents under heavy load conditions without affecting the use feel of the power tools.
  • an electric tool including: a casing; a motor, a drive circuit arranged in the casing, the drive circuit includes a plurality of electronic switches; a control module, connected with the drive The circuit is electrically connected, the control module outputs a drive signal to control the drive circuit to run the motor; the current detection module is used to obtain the current value of the motor; the control module is also configured to: Obtain the phase current value of the motor in real time through the current detection module within the time interval; when the acquired phase current value exceeds the preset current threshold, turn off the current value that is being turned on during the remaining time of the current time interval The electronic switch in the state, when the previous drive signal cycle ends, the electronic switch currently controlled by the control module is turned on; the duration of each time interval in the periodic time interval is the same as the The current period corresponding to the driving signal is the same; the period of the driving signal changes randomly within the second preset period range.
  • the random variation of the period of the driving signal within the range of the second preset period follows a law of normal distribution.
  • the preset current threshold is not fixed and satisfies the change law of the preset waveform.
  • the period of the preset waveform is the same as the period of the driving signal or the duration of each time interval in the periodic time intervals.
  • the preset waveform is set as a triangular waveform or a waveform containing a curve.
  • the preset current threshold corresponding to the end of the current time interval is smaller than the preset current threshold corresponding to the start of the current time interval.
  • the electric tool further includes a power input device and a rectification module; the power input device is used to access the power required for the operation of the electric tool; the rectification module is configured to be connected to the power input The device is electrically connected to convert the electric energy of the power input device into direct current for use by the electric tool.
  • the electric tool further includes a power supply circuit and a capacitor circuit; the power supply circuit is electrically connected to the rectifier module to at least supply power to the control module; the capacitor circuit is electrically connected to the rectifier module and between the drive circuits.
  • the capacitive circuit includes at least one electrolytic capacitor.
  • the ratio of the capacitance of the electrolytic capacitor to the rated power of the motor is greater than 20 ⁇ F/kW and less than 80 ⁇ F/kW.
  • the rectification module includes a rectification bridge composed of four diodes D1, D2, D3, D4.
  • the current detection module is electrically connected between the control module and the motor; the current detection module includes a plurality of current detection resistors.
  • the motor is configured as a brushless DC motor.
  • the brushless DC motor is controlled by the drive signal.
  • the electric tool further includes a rotation speed detection module, configured to acquire the rotation speed of the motor or the rotor position of the motor.
  • An electric tool comprising: a casing; a motor disposed in the casing; a drive circuit, the drive circuit including a plurality of electronic switches; a control module, electrically connected to the drive circuit, and the control module outputs a drive
  • the signal controls the driving circuit to run the motor;
  • the current detection module is used to obtain the current value of the motor;
  • the control module is also configured to: obtain the current value in real time through the current detection module in a periodic time interval The phase current value of the motor; when the obtained phase current value exceeds the preset current threshold value, the electronic switch that is in the conduction state is turned off during the remaining time of the current time interval, and the current one
  • the electronic switch currently controlled by the control module is turned on; the period of the driving signal changes randomly within the second preset period range.
  • the duration of each of the periodic time intervals is the same as the current period of the drive signal.
  • the preset current threshold is not fixed and satisfies the change law of the preset waveform.
  • a control method of an electric tool includes a housing; a motor, arranged in the housing; a drive circuit, the drive circuit includes a plurality of electronic switches; a current detection module, used to obtain the current of the motor value; a control module, electrically connected to the drive circuit; the control method includes: the control module outputs a drive signal to control the drive circuit to run the motor, and the motor is controlled at periodic time intervals The current is limited; the control module obtains the phase current value of the motor in real time through the current detection module in the periodic time interval; if the current value exceeds the preset current threshold, the current time interval Turn off the electronic switch that is in the conduction state within the remaining time, and then turn on the electronic switch currently controlled by the control module when the current cycle of the driving signal ends; the periodic time The duration of each time interval in the interval is the same as the period corresponding to the current driving signal; the period of the driving signal varies randomly within the range of the second preset period.
  • the random variation within the second preset period follows the law of normal distribution.
  • the electric tool and its control method disclosed in this embodiment can effectively limit the large current of the electric tool under heavy load conditions, and set the period of the driving signal within the preset range to meet the randomness of the normal distribution law. Change, reduce the EMI characteristics of the drive circuit through the frequency shaking strategy, optimize the use feel of the electric tool to a large extent, and improve the reliability and life of the electric tool.
  • An electric tool comprising: a housing; a motor disposed in the housing; a drive circuit, the drive circuit including a plurality of electronic switches; a current detection module, used to obtain the phase current value of the motor; a control module, Electrically connected with the drive circuit, the control module outputs a drive signal to control the drive circuit to run the motor; the control module is also configured to: pass the current detection module in real time in a periodic time interval Obtain the phase current value of the motor; when the obtained phase current value exceeds the current current threshold, turn off the electronic switch that is in the conduction state during the remaining time of the current time interval, and in the current one When the period of the driving signal ends, the electronic switch currently controlled by the control module is turned on; the current threshold is not fixed and meets the change rule of the preset waveform; the period of the preset waveform is consistent with the period The duration of each of the time intervals is the same.
  • the preset waveform is set as a triangular waveform or a waveform containing a curve.
  • the current threshold corresponding to the end of the current time interval is smaller than the current threshold corresponding to the start of the current time interval.
  • the duration of each of the periodic time intervals is the same as the current period of the drive signal.
  • control module controls the period of the driving signal to change continuously or randomly.
  • the electric tool further includes a power supply device and a rectification module; the power supply device is used to receive electric energy during operation of the electric tool; the rectification module is electrically connected to the power supply device.
  • the electric tool further includes a power supply circuit and a capacitor circuit; the power supply circuit is electrically connected to the rectifier module to at least supply power to the control module; the capacitor circuit is electrically connected to the rectifier module and between the drive circuits.
  • the capacitive circuit includes at least one electrolytic capacitor.
  • the current detection module includes a plurality of current detection resistors.
  • the motor is configured as a brushless DC motor, and the brushless DC motor is controlled by the driving signal.
  • a control method of an electric tool includes a housing; a motor, arranged in the housing; a drive circuit, the drive circuit includes a plurality of electronic switches; a current detection module, used to obtain the current of the motor value; a control module, electrically connected to the drive circuit; the control method includes: the control module outputs a drive signal to control the drive circuit to run the motor, and the motor is controlled at periodic time intervals The current is limited; the control module obtains the phase current value of the motor in real time through the current detection module within the periodic time interval; if the phase current value exceeds the current current threshold, at the current time Turn off the electronic switch that is in the conduction state in the remaining time of the interval, and then turn on the electronic switch currently controlled by the control module when the current cycle of the driving signal ends; the current threshold is not
  • the change rule of the preset waveform is fixed and satisfied; the period of the preset waveform is the same as the duration of each time interval in the periodic time intervals.
  • the preset waveform is a triangular waveform or a waveform containing curves at periodic time intervals.
  • the current threshold corresponding to the end of the current time interval is smaller than the current threshold corresponding to the start of the current time interval.
  • the duration of each of the periodic time intervals is the same as the current period of the drive signal.
  • control module controls the period of the driving signal to change continuously or randomly.
  • the electric tool and its control method disclosed in this embodiment can effectively limit the high current of the electric tool under heavy load conditions, and at the same time optimize the cycle of the driving signal to weaken the impact of fluctuations in the grid voltage, to a greater extent Optimize the use feel of electric tools, improve the reliability and life of electric tools.
  • An electric tool comprising: a casing; a motor disposed in the casing; a drive circuit, the drive circuit including a plurality of electronic switches; a control module, electrically connected to the drive circuit, and the control module outputs a drive
  • the signal controls the driving circuit to run the motor;
  • the current detection module is used to obtain the current value of the motor;
  • the control module is also configured to: obtain the current value in real time through the current detection module in a periodic time interval The phase current value of the motor; when the obtained phase current value exceeds the preset current threshold value, the electronic switch that is in the conduction state is turned off during the remaining time of the current time interval, and the current one
  • the electronic switch currently controlled by the control module is turned on; the duration of each time interval in the periodic time interval is the same as the current period corresponding to the driving signal;
  • the period of the driving signal changes continuously within the range of the first preset period.
  • the continuous change is set to be such that when the current grid voltage is lower than or equal to the current back electromotive force of the motor, the period of the driving signal remains unchanged.
  • the continuous change is set to be that when the current grid voltage is higher than the back electromotive force of the motor, the cycle of the driving signal changes continuously within the first preset cycle range.
  • the continuous variation satisfies the law of a sine function.
  • the electric tool further includes a power input device and a rectification module; the power input device is used to access the power required for the operation of the electric tool; the rectification module is configured to be connected to the power input The device is electrically connected to convert the electric energy of the power input device into direct current for use by the electric tool.
  • the electric tool further includes a power supply circuit and a capacitor circuit; the power supply circuit is electrically connected to the rectifier module to at least supply power to the control module; the capacitor circuit is electrically connected to the rectifier module and between the drive circuits.
  • the capacitive circuit includes at least one electrolytic capacitor.
  • the current detection module includes a plurality of current detection resistors.
  • the motor is configured as a brushless DC motor.
  • the brushless DC motor is controlled by the drive signal.
  • the electric tool and its control method disclosed in this embodiment can effectively limit the large current of the electric tool under heavy load conditions, and at the same time effectively compensate the fluctuation of the grid voltage, thereby optimizing the use of the electric tool to a large extent Feel, improve the reliability and life of electric tools.
  • An electric tool comprising: a casing; a motor set in the casing; a drive circuit, the drive circuit includes a plurality of electronic switches; a current detection module, used to obtain the current value of the motor; a control module, and The drive circuit is electrically connected, and the control module outputs a drive signal of a given period to control the drive circuit to run the motor; the phase current value of the motor is obtained in real time through the current detection module; the control module also It is configured to: if the obtained current value is higher than a first preset current threshold, turn off the electronic switch that is in the conduction state until the obtained current value is lower than a second preset current threshold At this time, the electronic switch currently controlled by the control module is turned on.
  • the first preset current threshold is greater than the second preset current threshold.
  • the electric tool further includes a power input device and a rectification module; the power input device is used to access the power required for the operation of the electric tool; the rectification module is configured to be connected to the power input The device is electrically connected to convert the electric energy of the power input device into direct current for use by the electric tool.
  • the electric tool further includes a power supply circuit and a capacitor circuit; the power supply circuit is electrically connected to the rectifier module to at least supply power to the control module; the capacitor circuit is electrically connected to the rectifier module and between the drive circuits.
  • the capacitive circuit includes at least one electrolytic capacitor.
  • the ratio of the capacitance of the electrolytic capacitor to the rated power of the motor is greater than 20 ⁇ F/kW and less than 80 ⁇ F/kW.
  • the rectification module includes a rectification bridge composed of four diodes D1, D2, D3, D4.
  • the current detection module is electrically connected between the control module and the motor; the current detection module includes a plurality of current detection resistors; the current detection module includes a plurality of current detection resistors.
  • the motor is configured as a brushless DC motor.
  • the brushless DC motor is controlled by the drive signal.
  • the electronic switch by setting the first preset current threshold and the second current threshold, once it is detected that the phase current exceeds the first preset current threshold, the electronic switch is turned off; When the phase current value is lower than the second preset current threshold, the electronic switch is turned on to resume the current flowing to the motor. While simply and effectively suppressing the large current during motor operation, it does not affect the use feel of the electric tool, optimizes the use feel of the electric tool to a large extent, and improves the reliability and life of the electric tool.
  • Fig. 1 is a perspective view of an electric tool as an embodiment
  • Fig. 2 is the circuit block diagram of the circuit system as a kind of embodiment
  • Fig. 3 is a block circuit diagram of a rectifier module as an embodiment
  • Fig. 4 is a block circuit diagram of a current detection module as an embodiment
  • Fig. 5 is a block circuit diagram of a current detection module as another embodiment
  • Fig. 6 is a waveform diagram of a motor control signal
  • Fig. 7 is a waveform diagram of the motor current limiting control method
  • Fig. 8 is a flowchart of the motor current limiting control method
  • Fig. 9 is a waveform diagram of a PWM signal and a current-limiting period as the first embodiment
  • Fig. 10 is a waveform diagram of continuously changing frequency of the PWM signal as the first embodiment
  • Fig. 11 is a flow chart of the motor control method as the first embodiment
  • Fig. 12 is the waveform diagram of the PWM signal and the motor phase current as the second embodiment
  • Fig. 13 is a flow chart of a motor control method as a second embodiment
  • Fig. 14 is a waveform diagram of a PWM signal and a motor phase current as a third embodiment
  • Fig. 16 is a waveform diagram of the motor phase current when the preset current threshold is a fixed value
  • Fig. 17a is a waveform diagram of a PWM signal and a motor phase current as a fourth embodiment
  • Fig. 17b is a waveform diagram of PWM signals and motor phase currents as another implementation of the fourth embodiment
  • FIG. 18 is a flow chart of a motor control method as a fourth embodiment
  • Fig. 19 is a flowchart of a motor control method as another implementation of the fourth embodiment.
  • the electric tool of the present application may be a hand-held electric tool, a garden tool, or a garden vehicle such as a vehicle-type lawnmower, which is not limited herein.
  • the power tools in this application include but are not limited to AC power tools such as sanders, drills, impact drivers, tapping machines, and fastener drivers, as long as these power tools can adopt the essence of the technical solutions disclosed below, they can fall into this category The scope of protection applied for.
  • AC power tools such as sanders, drills, impact drivers, tapping machines, and fastener drivers
  • an electric tool 10 is exemplarily shown, which is an angle grinder.
  • the electric tool 10 mainly includes: a housing 11 , a motor 13 , functional components 14 , an AC power input device 15 and a circuit system 12 inside the housing 11 .
  • the electric machine 13 includes stator windings and a rotor.
  • the motor 13 is a three-phase brushless motor comprising a rotor with permanent magnets and electronically commutated three-phase stator windings U, V, W.
  • the three-phase stator windings U, V, W are connected in a star connection.
  • the three-phase stator windings U, V, and W are connected in an angled manner.
  • Brushless motors may include less or more than three phases.
  • the functional part 14 is used to realize the functions of the electric tool 10 .
  • the functional part 14 is driven and operated by the motor 13 .
  • the functional elements are different for different power tools.
  • the functional part 14 is an angle grinder, which is used for grinding or cutting.
  • the AC power input device 15 is used to access the power required for the electric tool 10 to work.
  • the power supply in this embodiment may optionally be set as an AC power supply.
  • the AC power input device 15 includes an AC plug for connecting to 120V or 220V AC mains.
  • the rectifier module 21 constitutes a DC unit of the electric tool 10 .
  • the rectification module 21 is configured to receive the AC power from the AC power input device 15 and output the DC bus voltage, that is, to convert the AC power input by the AC power input device 15 into a pulsating DC output.
  • the rectification module 21 is electrically connected to the AC power input device 15 .
  • the rectification module 21 includes a rectification bridge composed of four diodes D1, D2, D3, and D4. direction of the pulsating DC output.
  • the capacitor circuit 22 is connected in parallel to the DC bus of the electric tool 10 , that is, connected in parallel between the positive and negative poles of the DC unit in the circuit system 12 .
  • the capacitor circuit 22 is optionally connected in parallel between the rectification module 21 and the drive circuit 24 .
  • the capacitor circuit 22 includes an electrolytic capacitor C.
  • the capacitor circuit 22 is electrically connected to the rectification module 21, and the pulsating direct current output by the rectification module 21 is filtered by the electrolytic capacitor C and converted into a smooth direct current output to reduce harmonic interference in the pulsating direct current.
  • the ratio of the capacitance of the electrolytic capacitor C to the rated power of the motor 13 is greater than 20 ⁇ F/KW and less than 80 ⁇ F/KW. This saves space and ensures that there are no capacitive elements with large physical dimensions in the hardware circuit.
  • the power supply circuit 23 is used to at least supply power to the control module 25 .
  • the power supply circuit 23 is electrically connected to the rectification module 21, and converts the electric energy rectified by the rectification module 21 into a power supply voltage output suitable for the control module 25.
  • the power supply circuit 23 reduces the voltage rectified by the rectification module 21 from the AC power input device 15 to 15V to supply power to the control module 25 .
  • the drive circuit 24 is electrically connected to the rectifier module 21 for driving the motor 13'.
  • the input terminal of the drive circuit 24 receives the voltage from the rectifier module 21, and under the drive of the drive signal output by the control module 25, the voltage is distributed to each phase winding on the stator of the motor 13 in a certain logical relationship, so that the motor 13 starts and generates Continuous torque.
  • the drive circuit 24 includes a plurality of electronic switches.
  • the electronic switch includes a field effect transistor (FET), in other embodiments the electronic switch includes an insulated gate bipolar transistor (IG-BT), or the like.
  • the driving circuit 24 is a three-phase bridge circuit.
  • the drive circuit 24 includes three electronic switches Q1 , Q3 , Q5 arranged as high-side switches and three electronic switches Q2 , Q4 , Q6 arranged as low-side switches.
  • Three electronic switches Q1 , Q3 , Q5 as high-side switches are respectively arranged between the power supply line of the rectifier module 21 and the coils of each phase of the motor 13 .
  • Three electronic switches Q2, Q4 and Q6 as low-side switches are respectively arranged between the coils of each phase of the motor 22 and the ground wire.
  • Each gate terminal UH, UL, VH, VL, WH, WL of the six electronic switches Q1 - Q6 is electrically connected to the control module 25 , and each drain or source of the electronic switch is connected to the stator winding of the motor 13 .
  • the electronic switches Q1 - Q6 change the on or off state at a certain frequency according to the driving signal output by the control module 25 , thereby changing the power state of the rectifier circuit 21 loaded on the winding of the motor 13 .
  • the drive circuit 24 is a circuit for rotationally driving the motor 13 by switching the energization state of each phase winding of the motor 13 and controlling the respective energization currents of each phase winding.
  • the order and timing of the conduction of each phase winding depends on the position of the rotor.
  • the driving circuit 24 In order to make the motor 13 rotate, the driving circuit 24 has multiple driving states. In one driving state, the stator winding of the motor 13 will generate a magnetic field.
  • the control module 25 outputs control signals based on different rotor positions to control the driving circuit 24 to switch the driving state so that The magnetic field generated by the stator winding rotates to drive the rotor to rotate, thereby realizing the driving of the motor 13 .
  • the rotation speed detection module 26 is used for acquiring at least one of the measured rotation speed of the motor 13 and the position of the rotor.
  • the rotational speed detection module 26 includes a sensor capable of directly detecting the speed and position of the motor 13 , such as a Hall sensor.
  • the rotation speed detection module 26 is configured to estimate the rotor position of the motor 13 at least according to the phase voltage of the motor 13 and the current value of the stator winding.
  • the current detection module 27 is used to collect the current of the motor 13 , which may be the bus current of the motor 13 or the phase current of each phase winding of the motor 13 .
  • the current detection module 27 detects the phase current of each phase winding of the motor 13, and the bus current of the motor 13 can be obtained by calculating the detected three-phase current values.
  • the current detection module 27 Hall current sensors are included to directly detect the phase currents of the respective phase windings of the motor 13 .
  • the current detection resistors R1, R2 and R3 are connected in series between the drive circuit 24 and each phase winding of the motor 13, and the current detection module 27 detects the voltage across the detection resistor.
  • the phase current or bus current of each phase winding can be calculated.
  • the current detection module 27 respectively detects the voltages at both ends of the current detection resistors R1, R2 and R3 to calculate the phase currents of the three-phase stator windings U, V and W.
  • the current detection module 27 is used to detect the internal resistance of the electronic switch in the conducting state in the drive circuit 24, based on the internal resistance of the electronic switch in the conducting state and its The voltage values at both ends are calculated to obtain the current passing through the electronic switch, and the current of the electronic switch is the phase current corresponding to the winding of the motor 13 .
  • the current detection module 27 respectively detects the voltages at both ends of the three drive switches Q1, Q3, and Q5 of the high-side switch to calculate the corresponding phase currents of the three-phase stator windings U, V, and W. In this way, the electric tool can detect the phase current corresponding to the winding of the motor 22 without adding hardware, which saves costs.
  • the control module 25 is at least electrically connected to the power supply circuit 23 , the driving circuit 24 and the current detection module 27 for controlling the operation of the driving circuit 24 .
  • the control module 25 adopts a dedicated control chip (for example, MCU, micro control unit, Microcontroller Unit).
  • the control module 25 outputs drive signals and applies them to the gate terminals UH, UL, VH, VL, WH, and WL of the six electronic switches Q1-Q6, respectively, for controlling multiple electronic switches Q1-Q6 to drive the motor 13.
  • the motor 13 is set as a three-phase brushless DC motor, and the driving signal is set as a PWM signal.
  • the period of the PWM signal is T 1 , and the control module 25 limits the current of the motor within the periodic time interval T 2 .
  • the periodic time interval here can be understood as the current limiting period of the motor, and T 2 is defined as the current limiting period of the motor in the following.
  • the current limiting period T2 is set to be the same as the period T1 of the PWM signal.
  • the control module 25 is configured to obtain the phase current value I phase of the motor 13 in real time through the current detection module 27 in the current cycle of the current limiting cycle T2, and compare the phase current value I phase with the preset current threshold value I ref . If the phase current value I phase exceeds the preset current threshold value I ref , then the electronic switch is turned off during the remaining time of the current cycle of the current limiting cycle T 2 , so as to cut off the current flowing to the motor 13, and in the current cycle of a PWM signal At the end of period T 1 , the electronic switch is turned on, restoring the current to the motor 13 .
  • the setting of the preset current threshold I ref can be set separately according to the type selection of the motor in the actual application and the actual application scenario.
  • the electronic switch that is turned off in this embodiment is specifically the electronic switch that is currently in the on state, and the electronic switch that is turned on is the electronic switch that is turned on under the control of the current driving signal.
  • the motor Under heavy load conditions, due to the large enough power supply capacity of the grid voltage, the motor will over-current, which will damage the components in the power tool and reduce the service life of the power tool. Referring to FIG. 7 , the motor has an overcurrent phenomenon under heavy load conditions, which is shown at point b in FIG. 7 .
  • the control module 25 when the phase current value I phase exceeds the preset current threshold I ref , the control module 25 immediately turns off the electronic switch so that the current flowing through the motor 13 does not increase any more, as shown by point a in the figure.
  • the control module 25 turns on the electronic switch again, so as to resume the current flowing to the motor 13 .
  • the current detection module detects the phase current of the motor 13 to realize cycle-by-cycle current limiting of the motor.
  • it can also be used to realize cycle-by-cycle current limiting of the motor by detecting the bus current value of the motor.
  • a control method for a current-limiting period of the motor in the electric tool 10 will be specifically described below in conjunction with FIG. 8 , and the method includes the following steps:
  • step S105 turn on the electronic switch controlled by the current driving signal, and return to step S101.
  • the control module 25 controls the period T1 of the PWM signal used to drive the motor 13 to continuously change within the first preset period range, and simultaneously sets the current limiting period T2 of the motor 13 and the PWM signal.
  • the period T1 of the signal is the same.
  • the first preset period range is optionally set to [0.5T 0 , 2T 0 ], and T 0 is an initial period of the PWM signal.
  • the period T1 of the PWM signal remains unchanged; Change continuously within the set range.
  • the period T1 of the driving signal is set to a continuous change within the range of the first preset period, which can be obtained by the following formula:
  • f 0 is the initial frequency corresponding to the initial period T 0 of the PWM signal
  • f 1 is the frequency corresponding to the period T 1 of the PWM signal
  • ⁇ is the phase of the current grid voltage
  • the above-mentioned first embodiment discloses a cycle-by-cycle current limiting control method for electric tools.
  • the current limiting cycle is always the same as the cycle of the PWM signal.
  • the electronic switch is turned off.
  • the electronic switch is turned on again, and at the same time, the phase current of the motor continues to be detected in real time.
  • setting the period of the PWM signal to continuously change within the first preset period range with the fluctuation of the grid voltage can effectively compensate for the fluctuation of the grid voltage, and improve the user's feeling of use and the service life of the electric tool.
  • the control module 25 controls the cycle T1 of the PWM signal used to drive the motor 13 to change randomly within the second preset cycle range, and sets the current limiting cycle T2 of the motor 13 to match the PWM signal.
  • the period T1 of the signal is always the same. Referring to FIG. 12, the period T1 of the PWM signal varies randomly within the second preset period range. Specifically, it can be set so that the initial period T 0 of the PWM signal is superimposed with white noise, and changes conform to the law of normal distribution.
  • the initial period T0 of the PWM signal used to drive the motor 13 is set to 100us, and the period T1 of the PWM signal after superimposing white noise changes randomly within the second preset period range [98us, 102us], and changes Satisfy the law of normal distribution.
  • the motor has an overcurrent phenomenon under heavy load conditions, which is shown at point b in Figure 12 .
  • the control module 25 immediately turns off the electronic switch so that the current flowing through the motor 13 does not rise any more, which is shown by point a in the figure.
  • the control module 25 turns on the electronic switch again, so as to resume the current flowing to the motor 13 .
  • the current detection module detects the phase current of the motor 13 to realize cycle-by-cycle current limiting of the motor.
  • it can also be used to realize cycle-by-cycle current limiting of the motor by detecting the bus current value of the motor.
  • the second preset range set in this embodiment should be set according to the actual application scene of the electric tool.
  • step S305 turn on the electronic switch controlled by the current driving signal, and return to step S301.
  • the second embodiment above discloses a cycle-by-cycle current limiting control method for electric tools.
  • the current limiting cycle is always the same as the cycle of the PWM signal.
  • the electronic switch is turned off.
  • the electronic switch is turned on again, and at the same time, the phase current of the motor continues to be detected in real time.
  • the period of the PWM signal is set to change randomly within the range of the second preset period, and the above random change satisfies the law of normal distribution.
  • the period of the PWM signal is set within a preset range to meet the random change of the normal distribution law, and the EMI of the driving circuit is reduced through the frequency shaking strategy, thereby improving the reliability of the electric tool.
  • the control module 25 outputs a PWM signal with an initial period T 0 to control the driving circuit 24 to drive the motor 13 .
  • the control module 25 obtains the phase current value of the motor 13 in real time through the current detection module 27 , and compares the obtained phase current value with a preset current range.
  • the preset current thresholds include a first preset current threshold I ref1 and a second preset current threshold I ref2 .
  • the first preset current threshold I ref1 is set as an upper limit
  • the second preset current threshold I ref2 is set as a lower limit.
  • the control module 25 When the phase current value I phase of the motor 13 obtained by the control module 25 is higher than the first preset current threshold I ref1 , the control module 25 immediately turns off the electronic switch that is currently on. When the phase current value I phase of the motor 13 acquired by the control module 25 is lower than the second preset current threshold I ref2 , the control module 25 controls to turn on the electronic switch turned on by the current driving signal.
  • the difference between the first preset current threshold I ref1 and the second preset current threshold I ref2 is inversely proportional to the inductance value of the motor and proportional to the back electromotive force during normal operation of the motor.
  • the preset current range can be reasonably designed according to the motor type selection and actual application scenarios.
  • step S405 turning on the electronic switch that is controlled to be turned on by the current driving signal. Return to step S401.
  • the above-mentioned third embodiment discloses a cycle-by-cycle current limiting control method for an electric tool.
  • the phase current of the motor is obtained through the current detection module, and once it is detected that the phase current exceeds the first preset current threshold, the electronic switch is turned off; once the phase current of the motor When the current value is lower than the second preset current threshold, the electronic switch is turned on to resume the current flowing to the motor.
  • the motor will not experience a large current phenomenon, thereby protecting the electronic components.
  • the preset current threshold is a fixed value, the current flowing through the motor may generate secondary harmonics.
  • the preset current threshold I ref is optionally set to a fixed value, and the phase current obtained in real time is compared with the preset current threshold I ref .
  • the phase current 1 is a waveform diagram of the phase current value I phase of the motor in a normal working state
  • the phase current 2 is a waveform diagram of the phase current value I phase of the motor after current limiting.
  • the preset current threshold I ref in this embodiment is not fixed and satisfies the change rule of the preset waveform.
  • the preset waveform can optionally be set as a triangular waveform, and the period T3 of the triangular waveform is the same as the current limiting period T2 .
  • the value range of the slope K of the triangular waveform is as follows:
  • I 0 is the phase current value at the moment of power-on. It can be understood that, for the setting of the specific value of I ref , those skilled in the art will usually conduct debugging according to a specific circuit, so as to obtain a more suitable value. It can be understood that the calculation method of the value range of the K value given in this embodiment, but the specific K value needs to be obtained by debugging the circuit within the above value range of the K value by those skilled in the art.
  • phase current 1 is a waveform diagram of the phase current of the motor without current limitation.
  • Phase current 2 is a waveform diagram of the phase current of the motor when the preset current threshold I ref is a fixed value.
  • Phase current 4 is a waveform diagram of the motor phase current when the preset current threshold I ref is a triangular waveform. It can be clearly seen from Fig. 17a that no obvious secondary harmonics will be generated in the phase current of the motor in the phase current 4.
  • the preset waveform in this embodiment is a triangular waveform.
  • the preset waveform can also be set as a waveform containing curves.
  • the waveform including the above - mentioned curve is defined here as waveform F
  • the period T4 of waveform F is the same as the current limiting period T2 .
  • the current value of the waveform F at the beginning of a current limiting period T 2 is the same as the current value of the triangular waveform at the beginning of a current limiting period T 2 .
  • the current value of the waveform F at the end of a current limiting period T 2 is the same as the current value of the triangular waveform at the end of a current limiting period T 2 .
  • phase current 2 is the waveform diagram of the motor phase current when the preset current threshold Imax is a fixed value
  • phase current 4 is the waveform diagram of the motor phase current when the preset current threshold Imax is waveform F. It can be clearly seen from Fig. 17b that no obvious secondary harmonics will be generated in the phase current of the motor in the phase current 4.
  • the specific parameters of the waveform F should be designed according to the specific circuit structure. It should also be noted here that the preset waveforms in the above embodiments are not limited to the triangular waveforms and waveforms containing curves described above.
  • the current threshold corresponding to the preset waveform at the end of the current current limiting period T2 is smaller than the current threshold corresponding to the beginning of the current current limiting period T2.
  • step S19 setting the current limiting period T and the period of the triangular waveform equal to the period of the current PWM signal.
  • step S27 turn on the electronic switch that is currently controlled by the driving signal, and return to step S21.

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Abstract

提供一种电动工具（10）及控制方法，电动工具（10）包括：壳体（11）；电机（13）；驱动电路（24）；控制模块（25）；电流检测模块（27）；控制模块（25）被配置为在周期性的时间间隔内实时获取电机（13）的相电流值；当获取到的相电流值超过预设电流阈值，在当前时间间隔的剩余时间内关断正处于导通状态的电子开关，在当前一个驱动信号周期结束时，开启控制模块（25）当前控制导通的电子开关；周期性的时间间隔中每个时间间隔的持续时间与驱动信号当前所对应的周期相同；驱动信号的周期在第二预设周期范围内随机变化。采用以上方案，能够有效抑制重载工况下的大电流的同时，不影响电动工具（10）的使用手感。

Description

电动工具及其控制方法
本申请要求在2021年05月12日提交中国专利局、申请号为202110525390.4的中国专利申请，在2021年05月12日提交中国专利局、申请号为202110518929.3的中国专利申请，在2021年05月12日提交中国专利局、申请号为202110519047.9的中国专利申请以及在2021年09月06日提交中国专利局、申请号为202111036354.8的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本申请涉及一种电动工具，具体涉及一种适用于交流电动工具的控制方法。
背景技术
交流电动工具在重载工况下，尤其对于高压无刷工具来说，由于电网的供电能力足够大，容易出现过电流现象，不仅易损坏电子元器件，也较大程度上明显地影响电动工具的使用手感。
发明内容
为解决相关技术的不足，本申请提供一种适用于交流电动工具的限流控制方法，能够有效抑制重载工况下的大电流的同时，不影响电动工具的使用手感。
为实现上述目标，本申请采用如下技术方案：一种电动工具，包括：壳体；电机，设置在所述壳体内驱动电路，所述驱动电路包括多个电子开关；控制模块，与所述驱动电路电性连接，所述控制模块输出驱动信号控制所述驱动电路以运行所述电机；电流检测模块，用于获取所述电机的电流值；所述控制模块还被配置为：在周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；当获取到的所述相电流值超过预设电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同；所述驱动信号的周期在第二预设周期范围内随机变化。
在一些实施例中，所述驱动信号的周期在所述第二预设周期范围内的所述随机变化遵循正态分布的规律。
在一些实施例中，所述预设电流阈值不固定且满足预设波形的的变化规律。
在一些实施例中，所述预设波形的周期与所述驱动信号的周期或所述周期性的时间间隔中每个时间间隔的持续时间相同。
在一些实施例中，所述预设波形设置为三角波形或包含曲线的波形。
在一些实施例中，当前所述时间间隔结束时所对应的预设电流阈值小于当前所述时间间隔开始时所对应的预设电流阈值。
在一些实施例中，所述电动工具还包括电源输入装置和整流模块；所述电源输入装置用于接入所述电动工具工作时所需的电源；所述整流模块设置为与所述电源输入装置电连接，将所述电源输入装置的电能转换成直流电供所述电动工具使用。
在一些实施例中，所述电动工具还包括供电电路和电容电路；所述供电电路与所述整流模块电连接以至少为所述控制模块供电；所述电容电路电连接在所述整流模块和所述驱动电路之间。
在一些实施例中，所述电容电路至少包括一个电解电容。
在一些实施例中，所述电解电容的容值与所述电机的额定功率之比大于20μF/kW且小于80μF/kW。
在一些实施例中，所述整流模块括由四个二极管D1、D2、D3、D4组成的整流桥。
在一些实施例中，所述电流检测模块电连接在所述控制模块和所述电机之间；所述电流检测模块包括多个检流电阻。
在一些实施例中，所述电机设置为无刷直流电机。
在一些实施例中，所述无刷直流电机由所述驱动信号控制。
在一些实施例中，所述电动工具还包括转速检测模块，用于获取所述电机的转速或所述电机的转子位置。
一种电动工具，包括：壳体；电机，设置在所述壳体内；驱动电路，所述驱动电路包括多个电子开关；控制模块，与所述驱动电路电性连接，所述控制模块输出驱动信号控制所述驱动电路以运行所述电机；电流检测模块，用于获取所述电机的电流值；所述控制模块还被配置为：在周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；当获取到的所述相电流值超过预设电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；所述驱动信号的周期在第二预设周期范围内随机变化。
在一些实施例中，所述周期性的时间间隔中每个时间间隔的持续时间与所 述驱动信号当前所对应的周期相同。
在一些实施例中，所述预设电流阈值不固定且满足预设波形的的变化规律。
一种电动工具的控制方法，所述电动工具包括壳体；电机，设置在所述壳体内；驱动电路，所述驱动电路包括多个电子开关；电流检测模块，用于获取所述电机的电流值；控制模块，与所述驱动电路电性连接；所述控制方法包括：所述控制模块输出驱动信号控制所述驱动电路运行所述电机，并在周期性的时间间隔内对所述电机的电流实施限制；所述控制模块在所述周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；若所述电流值超过预设电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，再在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同；所述驱动信号的周期在第二预设周期范围内随机变化。
在一些实施例中，所述第二预设周期范围内的随机变化遵循正态分布的规律。
本实施例中公开的一种电动工具及其控制方法，有效地限制电动工具在重载工况下大电流的同时，过将驱动信号的周期设置在预设范围内满足正态分布规律的随机变化，通过抖频率策略减小驱动电路的EMI特征，较大程度上优化了电动工具的使用手感，提高了电动工具的可靠性以及寿命。
一种电动工具，包括：壳体；电机，设置于所述壳体内；驱动电路，所述驱动电路包括多个电子开关；电流检测模块，用于获取所述电机的相电流值；控制模块，与所述驱动电路电性连接，所述控制模块输出驱动信号控制所述驱动电路以运行所述电机；所述控制模块还被配置为：在周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；当获取到的所述相电流值超过当前的电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；所述电流阈值不固定且满足预设波形的的变化规律；所述预设波形的周期与所述周期性的时间间隔中每个时间间隔的持续时间相同。
在一些实施例中，所述预设波形设置为三角波形或包含曲线的波形。
在一些实施例中，当前所述时间间隔结束时所对应的电流阈值小于当前所述时间间隔开始时所对应的电流阈值。
在一些实施例中，所述周期性的时间间隔中每个时间间隔的持续时间与所 述驱动信号当前所对应的周期相同。
在一些实施例中，所述控制模块控制所述驱动信号的周期连续变化或随机变化。
在一些实施例中，所述电动工具还包括电源装置和整流模块；所述电源装置用于接入所述电动工具工作时的电能；所述整流模块与所述电源装置电性连接。
在一些实施例中，所述电动工具还包括供电电路和电容电路；所述供电电路与所述整流模块电性连接以至少为所述控制模块供电；所述电容电路电连接在所述整流模块和所述驱动电路之间。
在一些实施例中，所述电容电路至少包括一个电解电容。
在一些实施例中，所述电流检测模块包括多个检流电阻。
在一些实施例中，所述电机设置为无刷直流电机，所述无刷直流电机由所述驱动信号控制。
一种电动工具的控制方法，所述电动工具包括壳体；电机，设置在所述壳体内；驱动电路，所述驱动电路包括多个电子开关；电流检测模块，用于获取所述电机的电流值；控制模块，与所述驱动电路电性连接；所述控制方法包括：所述控制模块输出驱动信号控制所述驱动电路运行所述电机，并在周期性的时间间隔内对所述电机的电流实施限制；所述控制模块在所述周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；若所述相电流值超过当前的电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，再在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；所述电流阈值不固定且满足预设波形的的变化规律；所述预设波形的周期与所述周期性的时间间隔中每个时间间隔的持续时间相同。
在一些实施例中，所述预设波形在周期性的时间间隔内为三角波形或包含曲线的波形。
在一些实施例中，当前所述时间间隔结束时所对应的电流阈值小于当前所述时间间隔开始时所对应的电流阈值。
在一些实施例中，所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同。
在一些实施例中，所述控制模块控制所述驱动信号的周期连续变化或随机变化。
本实施例中公开的一种电动工具及其控制方法，有效地限制电动工具在重载工况下大电流的同时，通过优化驱动信号的周期从而削弱电网电压带来波动影响，较大程度上优化了电动工具的使用手感，提高了电动工具的可靠性以及寿命。
一种电动工具，包括：壳体；电机，设置在所述壳体内；驱动电路，所述驱动电路包括多个电子开关；控制模块，与所述驱动电路电性连接，所述控制模块输出驱动信号控制所述驱动电路以运行所述电机；电流检测模块，用于获取所述电机的电流值；所述控制模块还被配置为：在周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；当获取到的所述相电流值超过预设电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同；所述驱动信号的周期在第一预设周期范围内连续变化。
在一些实施例中，所述连续变化设置为当前电网电压低于或等于当前电机反电动势时，所述驱动信号的周期保持不变。
在一些实施例中，所述连续变化设置为所述当前电网电压高于所述电机的反电动势时，所述驱动信号的周期在所述第一预设周期范围内连续变化。
在一些实施例中，所述连续变化满足正弦函数的规律。
在一些实施例中，所述电动工具还包括电源输入装置和整流模块；所述电源输入装置用于接入所述电动工具工作时所需的电源；所述整流模块设置为与所述电源输入装置电连接，将所述电源输入装置的电能转换成直流电供所述电动工具使用。
在一些实施例中，所述电动工具还包括供电电路和电容电路；所述供电电路与所述整流模块电连接以至少为所述控制模块供电；所述电容电路电连接在所述整流模块和所述驱动电路之间。
在一些实施例中，所述电容电路至少包括一个电解电容。
在一些实施例中，所述电流检测模块包括多个检流电阻。
在一些实施例中，所述电机设置为无刷直流电机。
在一些实施例中，所述无刷直流电机由所述驱动信号控制。
本实施例公开的一种电动工具及其控制方法，有效地限制电动工具在重载工况下大电流的同时，还对电网电压的波动进行有效补偿，较大程度上优化了 电动工具的使用手感，提高了电动工具的可靠性以及寿命。
一种电动工具，包括：壳体；电机，设置在所述壳体内；驱动电路，所述驱动电路包括多个电子开关；电流检测模块，用于获取所述电机的电流值；控制模块，与所述驱动电路电性连接，所述控制模块输出给定周期的驱动信号控制所述驱动电路运行所述电机；通过所述电流检测模块实时获取所述电机的相电流值；所述控制模块还被配置为：若获取到的所述电流值高于第一预设电流阈值时，关闭正处于导通状态的所述电子开关，直至获取到的所述电流值低于第二预设电流阈值时开启所述控制模块当前控制导通的所述电子开关。
在一些实施例中，所述第一预设电流阈值大于所述第二预设电流阈值。
在一些实施例中，所述电动工具还包括电源输入装置和整流模块；所述电源输入装置用于接入所述电动工具工作时所需的电源；所述整流模块设置为与所述电源输入装置电连接，将所述电源输入装置的电能转换成直流电供所述电动工具使用。
在一些实施例中，所述电动工具还包括供电电路和电容电路；所述供电电路与所述整流模块电连接以至少为所述控制模块供电；所述电容电路电连接在所述整流模块和所述驱动电路之间。
在一些实施例中，所述电容电路至少包括一个电解电容。
在一些实施例中，所述电解电容的容值与所述电机的额定功率之比大于20μF/kW且小于80μF/kW。
在一些实施例中，所述整流模块括由四个二极管D1、D2、D3、D4组成的整流桥。
在一些实施例中，所述电流检测模块电连接在所述控制模块和所述电机之间；所述电流检测模块包括多个检流电阻；所述电流检测模块包括多个检流电阻。
在一些实施例中，所述电机设置为无刷直流电机。
在一些实施例中，所述无刷直流电机由所述驱动信号控制。
本实施例公开的一种电动工具及其控制方法，通过设置第一预设电流阈值和第二电流阈值，一旦检测到相电流超出第一预设电流阈值，则关断电子开关；一旦电机的相电流值低于第二预设电流阈值时，则开启电子开关，恢复流向电机的电流。简单有效地抑制电机工作中的出现的大电流的同时，不影响电动工具的使用手感，较大程度上优化了电动工具的使用手感，提高了电动工具的可靠性以及寿命。
附图说明
图1是作为一种实施例的电动工具的立体图；
图2是作为一种实施例的电路系统的电路框图；
图3是作为一种实施例的整流模块的电路框图；
图4是作为一种实施例的电流检测模块的电路框图；
图5是作为另一种实施例的电流检测模块的电路框图；
图6是电机控制信号的波形图；
图7是电机限流控制方法的波形图；
图8是电机限流控制方法的流程图；
图9是作为第一实施例的PWM信号和限流周期的波形图；
图10是作为第一实施例的PWM信号的频率连续变化波形图；
图11是作为第一实施例的电机的控制方法的流程图；
图12是作为第二种实施例的PWM信号和电机相电流的波形图；
图13是作为第二种实施例的电机的控制方法的流程图；
图14是作为第三实施例的PWM信号和电机相电流的波形图；
图15是作为第三实施例的电机的控制方法的流程图；
图16是预设电流阈值为固定值时的电机相电流的波形图；
图17a是作为第四实施例的PWM信号和电机相电流的波形图；
图17b是作为第四实施例的另一种实现方式的PWM信号和电机相电流的波形图；
图18是作为第四实施例的电机的控制方法的流程图；
图19是作为第四实施例的另一种实现方式的电机的控制方法的流程图。
具体实施方式
以下结合附图和具体实施例对本申请作具体的介绍。
本申请的电动工具，可以为手持式电动工具、花园类工具、花园类车辆如车辆型割草机，在此并非有所限制。本申请的电动工具包括但不限于砂光机、钻头、冲击起子、攻丝机、紧固件起子等交流电动工具，只要这些电动工具能够采用以下披露的技术方案的实质内容即可落入本申请的保护范围。另外还需 要说明的是，为了便于描述，附图中仅示出了与本申请相关的部分而非全部结构。
参考图1所示，示例性地示出一种电动工具10，该电动工具为角磨。电动工具10主要包括：壳体11、电机13、功能件14、交流电源输入装置15以及位于壳体11内的电路系统12。
电机13包括定子绕组和转子。在一些实施例中，电机13为三相无刷电机，包括具有永磁体的转子和以电子方式换向的三相定子绕组U、V、W。在一些实施例中，三相定子绕组U、V、W之间采用星型连接。在另一些实施例中，三相定子绕组U、V、W之间采用角型连接。然而，必须理解的是其他类型的无刷电动机也在本公开的范围。无刷电动机可包括少于或多于三相。
功能件14用于实现电动工具10的功能。功能件14由电机13驱动运行。对于不同电动工具而言，功能元件不同。对角磨而言，功能件14为角磨盘，用于实现打磨或切割功能。
交流电源输入装置15用于接入电动工具10工作所需的电源。作为具体实施方式的一种，本实施例的电源可选地设置为交流电源。具体地，交流电源输入装置15包括交流电插头，以接入120V或220V的交流市电。
参照图2所示的电动工具10的一种实施方式的电路系统12，主要包括整流模块21、电容电路22、供电电路23、驱动电路24、控制模块25、转速检测模块26以及电流检测模块27。
整流模块21构成电动工具10的直流单元。整流模块21设置为接收来自交流电源输入装置15的交流电并用于输出直流母线电压，也即用于将交流电源输入装置15输入的交流电转化为脉动直流电输出。整流模块21与交流电源输入装置15电性连接。作为具体实施方式的一种，参照图3所示，整流模块21包括由四个二极管D1、D2、D3、D4组成的整流桥，利用二极管的单向导电性和管压降将交流电转换成同一方向的脉动直流电输出。
电容电路22并联于电动工具10的直流母线上，即并联在电路系统12中直流单元的正负极之间。作为具体实施方式的一种，电容电路22可选地并联在整流模块21与驱动电路24之间。具体地，电容电路22包括电解电容C。电容电路22与整流模块21电性连接，整流模块21输出的脉动直流电经电解电容C滤波转化为平滑直流电输出，以降低脉动直流电中的谐波干扰。可选地，电解电容C的容值与电机13的额定功率之比大于20μF/KW且小于80μF/KW。这样可节约空间，保证在硬件电路中不存在物理尺寸较大的电容元件。
供电电路23用于至少为控制模块25供电。作为具体实施方式的一种，供 电电路23与整流模块21电连接，将经整流模块21整流后的电能转换为适配于控制模块25的供电电压输出。例如，为了给控制模块25供电，供电电路23将来自交流电源输入装置15并经整流模块21整流后的电压降到15V以为控制模块25供电。
驱动电路24与整流模块21电连接，用于驱动电机13,。驱动电路24的输入端接收来自整流模块21的电压，在控制模块25输出的驱动信号的驱动下将电压以一定的逻辑关系分配给电机13定子上的各相绕组，以使电机13启动并产生持续不断的转矩。具体地，驱动电路24包括多个电子开关。在一些实施例中，电子开关包括场效应晶体管(FET)，在另一些实施例中，电子开关包括绝缘栅双极晶体管(IG-BT)等。在一些实施例中，驱动电路24为三相桥式电路。驱动电路24包括作为高侧开关设置的三个电子开关Q1、Q3、Q5和作为低侧开关设置的三个电子开关Q2、Q4、Q6。
作为高端开关的三个电子开关Q1、Q3、Q5分别设在整流模块21的供电线与电机13的各相线圈之间。作为低端开关的三个电子开关Q2、Q4、Q6分别设在电机22的各相线圈与地线之间。
六个电子开关Q1-Q6的各个栅极端UH、UL、VH、VL、WH、WL与控制模块25电性连接，电子开关的每个漏极或源极与电机13的定子绕组连接。电子开关Q1-Q6依据控制模块25输出的驱动信号以一定频率改变导通或关断状态，从而改变整流电路21加载在电机13绕组上的功率状态。
驱动电路24是用于通过切换对电机13的各相绕组的通电状态、控制各相绕组各自的通电电流来使电机13旋转驱动的电路。各相绕组导通顺序和时间取决于转子的位置。为了使电机13转动，驱动电路24具有多个驱动状态，在一个驱动状态下电机13的定子绕组会产生一个磁场，控制模块25基于不同的转子位置输出控制信号以控制驱动电路24切换驱动状态使定子绕组产生的磁场转动以驱动转子转动，进而实现对电机13的驱动。
转速检测模块26用于获取电机13的实测转速和转子的位置中的至少一个。在一些实施例方式中，转速检测模块26包括传感器，传感器能够直接检测电机13的速度和位置，例如霍尔传感器。在另一些实施例中，转速检测模块26被配置为至少依据电机13的相电压和定子绕组的电流值估算电机13的转子位置。
电流检测模块27用于采集电机13的电流，电流可以是电机13的母线电流或电机13各相绕组的相电流。作为具体实施方式的一种，电流检测模块27检测电机13的各相绕组的相电流，电机13的母线电流则可以由检测到的三相电流值计算获得，一些实施例中，电流检测模块27包括霍尔电流传感器以直接检测电机13的各相绕组的相电流。作为具体实施方式的另一种，参考图4所示， 在驱动电路24和电机13的各相绕组之间分别串联检流电阻R1、R2和R3，电流检测模块27通过检测检测电阻两端的电压即可计算得出各相绕组的相电流或母线电流。具体地，电流检测模块27分别检测各个检流电阻R1、R2和R3两端的电压即可计算得出三相定子绕组U、V、W的相电流。作为具体实施例的另一种，参见图5所示，电流检测模块27用于检测驱动电路24中处于导通状态的电子开关的内阻，基于处于导通状态的电子开关的内阻和其两端的电压值计算得出经过该电子开关的电流，电子开关的电流即为对应电机13绕组的相电流。具体地，电流检测模块27分别检测高端开关的三个驱动开关Q1、Q3、Q5两端的电压计算得出对应的三相定子绕组U、V、W的相电流。这样，电动工具不用增加硬件即可检测对应电机22绕组的相电流，节约成本。
控制模块25至少电连接至供电电路23、驱动电路24以及电流检测模块27，用以控制驱动电路24工作。在一些实施方式中，控制模块25采用专用的控制芯片(例如，MCU，微控制单元，Microcontroller Unit)。
接下来将介绍作为本申请的第一实施例。
参照图6和图7所示，控制模块25输出驱动信号分别施加在六个电子开关Q1-Q6的栅极端UH、UL、VH、VL、WH、WL，用于控制多个电子开关Q1-Q6的导通状态以驱动电机13。电机13设置为三相无刷直流电机，驱动信号设置为PWM信号。PWM信号的周期为T 1，控制模块25在周期性的时间间隔T 2内对电机的电流实施限制。此处的周期性的时间间隔可以理解为电机的限流周期，下文将T 2定义为电机的限流周期。
参照图7所示，限流周期T 2设置为与PWM信号的周期T 1相同。控制模块25被配置为在限流周期T 2的当前一个周期内，通过电流检测模块27实时获取电机13的相电流值I phase，并将相电流值I phase与预设电流阈值I ref相比较。若相电流值I phase超过预设电流阈值I ref，那么在限流周期T 2的当前一个周期的剩余时间内关断电子开关，从而断开流向电机13的电流，并在当前一个PWM信号的周期T 1结束时开启电子开关，恢复流向电机13的电流。本实施例，预设电流阈值I ref的设置可以根据实际应用中电机选型以及实际应用场景另行设置。此处还需要说明的是，本实施例中的关断的电子开关具体为当前正处于导通状态的电子开关，开启的电子开关为当前驱动信号控制开启的电子开关。
重载工况下由于电网电压供电能力足够大，电机会出现过电流的现象，从而损坏电动工具中的元器件，降低电动工具的使用寿命。参照图7所示，电机在重载工况下出现了过流现象，即图7中的b点所示。采用上述限流技术方案，在相电流值I phase超过预设电流阈值I ref时,控制模块25立即关断电子开关使得流经电机13的电流不再升高，即图中a点所示。在PWM信号的当前一个周期结 束时，即图中c点所示，控制模块25重新开启电子开关，从而恢复流向电机13的电流。本实施例中，电流检测模块检测电机13的相电流，用于实现电机的逐周限流。当然，也可通过检测电机的母线电流值，用于实现电机的逐周限流。
下面将结合图8具体说明电动工具10中的电机的一个限流周期的控制方法，该方法包括以下步骤：
S101，获取电机相电流值。
S102，判断电机的相电流值是否超过预设电流阈值，若是，则执行步骤S103；若否，则执行步骤S104。
S103，关断当前导通的电子开关。
S104，判断当前限流周期是否结束，若是，则执行步骤S105；若否，则执行步骤S101。
S105，开启当前驱动信号控制开启的电子开关，返回步骤S101。
电网电压在电网负载较大幅度的增加或减少时，电网电压会出现波动现象，从而影响用户使用手感。
如图9所示，本实施例中，控制模块25控制用于驱动电机13的PWM信号的周期T 1在第一预设周期范围内连续变化，同时设置电机13的限流周期T 2与PWM信号的周期T 1相同。其中，第一预设周期范围可选地设置为[0.5T 0，2T 0]，T 0为PWM信号的初始周期。当电网电压低于或者等于当前电机13的反电动势时，PWM信号的周期T 1保持不变；反之，当电网电压高于当前电机13的反电动势时，PWM信号的周期T 1在第一预设范围内连续变化。结合图9和图10所示，驱动信号的周期T 1设置为第一预设周期范围内的连续变化可以通过如下公式获得：
Figure PCTCN2022081177-appb-000001
其中,f 0为与PWM信号的初始周期T 0相对应的初始频率，f 1为与PWM信号的周期T 1相对应的频率，θ为当前电网电压的相位。
下面将结合图11具体说明电动工具10中的电机13的逐周限流的控制方法，该方法包括以下步骤：
S201，获取电机的相电流值。
S202,判断电机的相电流值是否超过预设电流阈值，若是，则执行步骤S203；若否，则执行步骤S204。
S203,关断当前导通的电子开关。
S204,判断当前限流周期是否结束，若是，则执行步骤S205；若否，则执行步骤S206。
S205,开启当前驱动信号控制开启的电子开关。
S206，获取电网电压和电机反电动势。
S207，判断当前电机反电动势是否超过电网电压，若是，执行步骤S208，若否，执行步骤S201。
S208，重新设置驱动信号的的周期T1。
S209，重新设置限流周期T2，返回步骤S201。
上述的第一实施例公开一种电动工具逐周限流的控制方法，限流周期与PWM信号的周期始终相同，当检测到的电机相电流大于预设电流阈值时关闭电子开关，在PWM信号的当前一个周期结束时，重新开启电子开关，同时继续实时检测电机的相电流。另一方面设置PWM信号的周期随电网电压的波动在第一预设周期范围内连续变化，能够针对电网电压的波动进行有效补偿，提高用户使用手感与电动工具使用寿命。
接下来将介绍作为本申请的第二实施例。
与上述的第一实施例不同的是，控制模块25控制用于驱动电机13的PWM信号的周期T 1在第二预设周期范围内随机变化，并设置电机13的限流周期T 2与PWM信号的周期T 1始终相同。参见图12所示，PWM信号的周期T 1在第二预设周期范围内随机变化。具体地，可设置为将PWM信号的初始周期T 0叠加白噪声后符合正态分布的规律的变化。本实施例中，用于驱动电机13的PWM信号的初始周期T0设置为100us，叠加白噪声后的PWM信号的周期T 1在第二预设周期范围[98us，102us]内随机变化，并且变化满足正态分布的规律。
电机在重载工况下出现了过流现象，即图12中的b点所示。采用上述限流技术方案，在相电流值I phase超过预设电流阈值I ref时,控制模块25立即关断电子开关使得流经电机13的电流不再升高，即图中a点所示。在PWM信号的当前一个周期结束时，即图中c点所示，控制模块25重新开启电子开关，从而恢复流向电机13的电流。本实施例中，电流检测模块检测电机13的相电流，用于实现电机的逐周限流。当然，也可通过检测电机的母线电流值，用于实现电机的逐周限流。
需要注意的是，本实施例中设置的第二预设范围应根据电动工具实际应用场景自行设置。
下面将结合图13具体说明电动工具10中的电机13的逐周限流的控制方法，该方法包括以下步骤：
S301，获取电机的相电流值。
S302,判断电机的相电流值是否超过预设电流阈值，若是，则执行步骤S303；若否，则执行步骤S304。
S303,关断当前导通的电子开关。
S304,判断当前限流周期是否结束，若是，则执行步骤S305；若否，则执行步骤S301。
S305，重新设置驱动信号的周期T 1。
S305，根据重新设置后的驱动信号的周期T 1，设置限流周期T 2。
S305，开启当前驱动信号控制开启的电子开关，返回步骤S301。
上述的第二实施例公开一种电动工具逐周限流的控制方法，限流周期与PWM信号的周期始终相同，当检测到的电机相电流大于预设电流阈值时关闭电子开关，在PWM信号的当前一个周期结束时，重新开启电子开关，同时继续实时检测电机的相电流。另一方面设置PWM信号的周期在第二预设周期范围内随机变化，上述随机变化满足正态分布的规律。本实施例通过将PWM信号的周期设置在预设范围内满足正态分布规律的随机变化，通过抖频率策略减小驱动电路的EMI，提高电动工具的可靠性。
接下来将介绍作为本申请的第三实施例。
与上述实施例不同的是，参见图14所示，控制模块25输出初始周期为T 0的PWM信号，控制驱动电路24用于驱动电机13的运行。控制模块25通过电流检测模块27实时获取电机13的相电流值，并且将获取到的相电流值与预设电流范围进行比较。本实施例中，预设电流阈值包括第一预设电流阈值I ref1和第二预设电流阈值I ref2。第一预设电流阈值I ref1设置为上限值，第二预设电流阈值I ref2设置为下限值。当控制模块25获取到的电机13的相电流值I phase高于第一预设电流阈值I ref1时，控制模块25立即关断当前处于导通状态的电子开关。当控制模块25获取的电机13的相电流值I phase低于第二预设电流阈值I ref2时，控制模块25控制开启当前驱动信号控制开启的电子开关。在具体设置过程中，第一预设电流阈值I ref1与第二预设电流阈值I ref2的差值与电机的电感值成反比，与电机正常工作过程中的反电动势成正比，本领域技术人员可以根据电机选型以及实际应用场景进行合理设计预设电流范围。
下面将结合图15具体说明电动工具10中的电机13的逐周限流的控制方法， 该方法包括以下步骤：
S401，获取电机的相电流值。
S402,判断电机的相电流值是否高于第一预设电流阈值，若是，则执行步骤S403；若否，则执行步骤S404。
S403，关断当前导通的电子开关。
S404，判断电机相电流值是否低于第二预设电流阈值，若是，则执行步骤S405，若否，则执行步骤S401。
S405，开启当前驱动信号控制开启的电子开关。返回步骤S401。
上述的第三实施例公开一种电动工具逐周限流的控制方法，通过电流检测模块获取电机的相电流，一旦检测到相电流超出第一预设电流阈值，则关断电子开关；一旦电机的相电流值低于第二预设电流阈值时，则开启电子开关，恢复流向电机的电流。上述实施例中的技术方案，可以简单有效地抑制电机工作中的出现的大电流的同时，不影响电动工具的使用手感。
可以理解，上述的第一实施例和第二实施例中，通过设置预设电流阈值，使得电机不会出现大电流现象，从而保护了电子元器件。但由于上述的第一实施例和第二实施例中的限流周期的存在，使的当预设电流阈值为已固定值时，流经电机的电流可能会产生次级谐波。
接下来将介绍作为本申请的第四实施例。
参见图16所示，预设电流阈值I ref被可选地被设置为一固定值，将实时获取到的相电流与预设电流阈值I ref进行比较。其中，相电流1为正常工作状态下的电机的相电流值I phase的波形图，相电流2为经过限流后的电机的相电流值I phase的波形图。当相电流值I phase超过预设电流阈值I ref，那么在限流周期T 2的当前一个周期的剩余时间内关断当前正处于导通状态的电子开关，从而断开流向电机的电流，并在当前一个PWM信号的周期T 1结束时开启电子开关，恢复流向电机的电流。按照上述的限流方法，则会出现图16中的a点所示次级谐波，从而影响电动工具的正常运行。
为了解决上述第一实施例和第二实施例中存在的问题，本实施例中的预设电流阈值I ref不固定且满足预设波形的变化的规律。
参见图17a所示，预设波形可选地设置为三角波形，三角波形的周期T 3与限流周期T 2相同。三角波形的斜率K的取值范围如下：
Figure PCTCN2022081177-appb-000002
其中，I 0为上电瞬间的相电流值。可以理解的是，I ref的具体值的设置，本领域的技术人通常会根据具体的电路进行调试，从而获取一个比较合适的值。可以理解，本实施例给出的K值的取值范围的计算方式，但是具体的K值需要本领域技术人员在上述K值的取值范围内对电路进行调试而获取。
参见图17a所示，相电流1为未经过限流的电机相电流的波形图。相电流2为预设电流阈值I ref为固定值时的电机相电流的波形图。相电流4为预设电流阈值I ref为三角波形时的电机相电流的波形图。从图17a中可以明显看出，相电流4中的电机相电流中不会产生明显的次级谐波。
本实施例中的预设波形为三角波形。当然，预设波形还可以设置为包含曲线的波形。参见图17b所示，此处定义上述包含曲线的波形为波形F，波形F的周期T 4与限流周期T 2相同。可以理解，波形F在一个限流周期T 2开始时的电流值与三角波形在一个限流周期T 2开始时的电流值相同。同样的，波形F在一个限流周期T 2结束时的电流值与三角波形在一个限流周期T 2结束时的电流值相同。换而言之，图17a中的m点和n点分别对应图17b中的m’点和n’点。参见图17b所示，相电流2为预设电流阈值I max为固定值时的电机相电流的波形图，相电流4为预设电流阈值I max为波形F时的电机相电流的波形图。从图17b中可以明显看出，相电流4中的电机相电流中不会产生明显的次级谐波。当然，波形F的具体参数要根据具体电路结构进行设计。此处还要说明的是，上述实施例中的预设波形并不局限于上述介绍的三角波形和包含曲线的波形。预设波形在当前当前限流周期T 2结束时所对应的电流阈值小于当前限流周期T 2开始时所对应的电流阈值。
接下来，将以预设波形为三角波形为例，结合图18具体说明逐周限流的一种控制方法，该方法包括以下步骤：
S11，获取电机相电流值。
S12,判断电机相电流值是否超过当前的预设电流阈值，若是，则执行步骤S203；若否，则执行步骤S204。
S13,关断当前导通的电子开关。
S14,判断当前限流周期是否结束，若是，则执行步骤S205；若否，则执行步骤S206。
S15,开启当前PWM信号控制开启的电子开关。
S16，获取电网电压和电机反电动势。
S17，判断当前电机反电动势是否超过电网电压，若是，执行步骤S208，若否，执行步骤S201。
S18，重新设置PWM信号的的周期。
S19，设置限流周期T和三角波形周期等于当前的PWM信号的周期。返回步骤S201。
接下来，将以预设波形为三角波形为例，结合图19具体说明逐周限流的一种控制方法，该方法包括以下步骤：
S21，获取电机相电流值。
S22,判断电机相电流值是否超过当前的电流阈值，若是，则执行步骤S23；若否，则执行步骤S24。
S23,关断当前导通的电子开关。
S24,判断当前限流周期是否结束，若是，则执行步骤S25；若否，则执行步骤S21。
S25，重新设置PWM信号的周期。
S26，设置限流周期和三角波形周期等于当前的PWM信号的周期。
S27，开启当前驱动信号控制开启的电子开关，返回步骤S21。

Claims (55)

  1. 一种电动工具，包括：
    壳体；
    电机，设置在所述壳体内；
    驱动电路，所述驱动电路包括多个电子开关；
    控制模块，与所述驱动电路电性连接，所述控制模块输出驱动信号控制所述驱动电路以运行所述电机；
    电流检测模块，用于获取所述电机的电流值；
    所述控制模块还被配置为：
    在周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；
    当获取到的所述相电流值超过预设电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；
    其中，
    所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同；
    所述驱动信号的周期在第二预设周期范围内随机变化。
  2. 根据权利要求1所述的电动工具，其中，
    所述驱动信号的周期在所述第二预设周期范围内的所述随机变化遵循正态分布的规律。
  3. 根据权利要求1所述的电动工具，其中，
    所述预设电流阈值不固定且满足预设波形的的变化规律。
  4. 根据权利要求3所述的电动工具，其中，
    所述预设波形的周期与所述驱动信号的周期或所述周期性的时间间隔中每个时间间隔的持续时间相同。
  5. 根据权利要求4所述的电动工具，其中，
    所述预设波形设置为三角波形或包含曲线的波形。
  6. 根据权利要求5所述的电动工具，其中，
    当前所述时间间隔结束时所对应的预设电流阈值小于当前所述时间间隔开 始时所对应的预设电流阈值。
  7. 根据权利要求1所述的电动工具，其中，
    所述电动工具还包括电源输入装置和整流模块；所述电源输入装置用于接入所述电动工具工作时所需的电源；所述整流模块设置为与所述电源输入装置电连接，将所述电源输入装置的电能转换成直流电供所述电动工具使用。
  8. 根据权利要求7所述的电动工具，其中，
    所述电动工具还包括供电电路和电容电路；所述供电电路与所述整流模块电连接以至少为所述控制模块供电；所述电容电路电连接在所述整流模块和所述驱动电路之间。
  9. 根据权利要求8所述的电动工具，其中，
    所述电容电路至少包括一个电解电容。
  10. 根据权利要求9所述的电动工具，其中，
    所述电解电容的容值与所述电机的额定功率之比大于20μF/kW且小于80μF/kW。
  11. 根据权利要求10所述的电动工具，其中，
    所述整流模块括由四个二极管D1、D2、D3、D4组成的整流桥。
  12. 根据权利要求11所述的电动工具，其中，
    所述电流检测模块电连接在所述控制模块和所述电机之间；所述电流检测模块包括多个检流电阻。
  13. 根据权利要求1所述的电动工具，其中，
    所述电机设置为无刷直流电机。
  14. 根据权利要求13所述的电动工具，其中，
    所述无刷直流电机由所述驱动信号控制。
  15. 根据权利要求1所述的电动工具，其中，
    所述电动工具还包括转速检测模块，用于获取所述电机的转速或所述电机的转子位置。
  16. 一种电动工具，包括：
    壳体；
    电机，设置在所述壳体内；
    驱动电路，所述驱动电路包括多个电子开关；
    控制模块，与所述驱动电路电性连接，所述控制模块输出驱动信号控制所述驱动电路以运行所述电机；
    电流检测模块，用于获取所述电机的电流值；
    所述控制模块还被配置为：
    在周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；
    当获取到的所述相电流值超过预设电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；
    其中，所述驱动信号的周期在第二预设周期范围内随机变化。
  17. 根据权利要求16所述的电动工具，其中，
    所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同。
  18. 根据权利要求17所述的电动工具，其中，
    所述预设电流阈值不固定且满足预设波形的的变化规律。
  19. 一种电动工具的控制方法，所述电动工具包括壳体；电机，设置在所述壳体内；驱动电路，所述驱动电路包括多个电子开关；电流检测模块，用于获取所述电机的电流值；控制模块，与所述驱动电路电性连接；
    所述控制方法包括：
    所述控制模块输出驱动信号控制所述驱动电路运行所述电机，并在周期性的时间间隔内对所述电机的电流实施限制；
    所述控制模块在所述周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；若所述电流值超过预设电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，再在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；
    其中，
    所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同；所述驱动信号的周期在第二预设周期范围内随机变化。
  20. 根据权利要求19所述的控制方法，其中，
    所述第二预设周期范围内的随机变化遵循正态分布的规律。
  21. 一种电动工具，包括：
    壳体；
    电机，设置于所述壳体内；
    驱动电路，所述驱动电路包括多个电子开关；
    电流检测模块，用于获取所述电机的相电流值；
    控制模块，与所述驱动电路电性连接，所述控制模块输出驱动信号控制所述驱动电路以运行所述电机；
    所述控制模块还被配置为：
    在周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；
    当获取到的所述相电流值超过当前的电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；
    其中，
    所述电流阈值不固定且满足预设波形的的变化规律；
    所述预设波形的周期与所述周期性的时间间隔中每个时间间隔的持续时间相同。
  22. 根据权利要求21所述的电动工具，其中，
    所述预设波形设置为三角波形或包含曲线的波形。
  23. 根据权利要求22所述的电动工具，其中，
    当前所述时间间隔结束时所对应的电流阈值小于当前所述时间间隔开始时所对应的电流阈值。
  24. 根据权利要求23所述的电动工具，其中，
    所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同。
  25. 根据权利要求24所述的电动工具，其中，
    所述控制模块控制所述驱动信号的周期连续变化或随机变化。
  26. 根据权利要求21所述的电动工具，其中，
    所述电动工具还包括电源装置和整流模块；所述电源装置用于接入所述电动工具工作时的电能；所述整流模块与所述电源装置电性连接。
  27. 根据权利要求26所述的电动工具，其中，
    所述电动工具还包括供电电路和电容电路；所述供电电路与所述整流模块电性连接以至少为所述控制模块供电；所述电容电路电连接在所述整流模块和所述驱动电路之间。
  28. 根据权利要求27所述的电动工具，其中，
    所述电容电路至少包括一个电解电容。
  29. 根据权利要求21所述的电动工具，其中，
    所述电流检测模块包括多个检流电阻。
  30. 根据权利要求21所述的电动工具，其中，
    所述电机设置为无刷直流电机，所述无刷直流电机由所述驱动信号控制。
  31. 一种电动工具的控制方法，所述电动工具包括壳体；电机，设置在所述壳体内；驱动电路，所述驱动电路包括多个电子开关；电流检测模块，用于获取所述电机的电流值；控制模块，与所述驱动电路电性连接；
    所述控制方法包括：
    所述控制模块输出驱动信号控制所述驱动电路运行所述电机，并在周期性的时间间隔内对所述电机的电流实施限制；
    所述控制模块在所述周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；若所述相电流值超过当前的电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，再在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；
    其中，
    所述电流阈值不固定且满足预设波形的的变化规律；
    所述预设波形的周期与所述周期性的时间间隔中每个时间间隔的持续时间相同。
  32. 根据权利要求31所述的控制方法，其中，
    所述预设波形在周期性的时间间隔内为三角波形或包含曲线的波形。
  33. 根据权利要求32所述的控制方法，其中，
    当前所述时间间隔结束时所对应的电流阈值小于当前所述时间间隔开始时 所对应的电流阈值。
  34. 根据权利要求33所述的控制方法，其中，
    所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同。
  35. 根据权利要求34所述的控制方法，其中，
    所述控制模块控制所述驱动信号的周期连续变化或随机变化。
  36. 一种电动工具，包括：
    壳体；
    电机，设置在所述壳体内；
    驱动电路，所述驱动电路包括多个电子开关；
    控制模块，与所述驱动电路电性连接，所述控制模块输出驱动信号控制所述驱动电路以运行所述电机；
    电流检测模块，用于获取所述电机的电流值；
    所述控制模块还被配置为：
    在周期性的时间间隔内通过所述电流检测模块实时获取所述电机的相电流值；
    当获取到的所述相电流值超过预设电流阈值，在当前所述时间间隔的剩余时间内关断正处于导通状态的所述电子开关，在当前一个所述驱动信号周期结束时，开启所述控制模块当前控制导通的所述电子开关；
    其中，
    所述周期性的时间间隔中每个时间间隔的持续时间与所述驱动信号当前所对应的周期相同；
    所述驱动信号的周期在第一预设周期范围内连续变化。
  37. 根据权利要求36所述的电动工具，其中，
    所述连续变化设置为当前电网电压低于或等于当前电机反电动势时，所述驱动信号的周期保持不变。
  38. 根据权利要求37所述的电动工具，其中，
    所述连续变化设置为所述当前电网电压高于所述电机的反电动势时，所述驱动信号的周期在所述第一预设周期范围内连续变化。
  39. 根据权利要求38所述的电动工具，其中，
    所述连续变化满足正弦函数的规律。
  40. 根据权利要求36所述的电动工具，其中，
    所述电动工具还包括电源输入装置和整流模块；所述电源输入装置用于接入所述电动工具工作时所需的电源；所述整流模块设置为与所述电源输入装置电连接，将所述电源输入装置的电能转换成直流电供所述电动工具使用。
  41. 根据权利要求40所述的电动工具，其中，
    所述电动工具还包括供电电路和电容电路；所述供电电路与所述整流模块电连接以至少为所述控制模块供电；所述电容电路电连接在所述整流模块和所述驱动电路之间。
  42. 根据权利要求41所述的电动工具，其中，
    所述电容电路至少包括一个电解电容。
  43. 根据权利要求36所述的电动工具，其中，
    所述电流检测模块包括多个检流电阻。
  44. 根据权利要求36所述的电动工具，其中，
    所述电机设置为无刷直流电机。
  45. 根据权利要求44所述的电动工具，其中，
    所述无刷直流电机由所述驱动信号控制。
  46. 一种电动工具，包括：
    壳体；
    电机，设置在所述壳体内；
    驱动电路，所述驱动电路包括多个电子开关；
    电流检测模块，用于获取所述电机的电流值；
    控制模块，与所述驱动电路电性连接，所述控制模块输出给定周期的驱动信号控制所述驱动电路运行所述电机；通过所述电流检测模块实时获取所述电机的相电流值；
    其中，
    所述控制模块还被配置为：
    若获取到的所述电流值高于第一预设电流阈值时，关闭正处于导通状态的所述电子开关，直至获取到的所述电流值低于第二预设电流阈值时开启所述控制模块当前控制导通的所述电子开关。
  47. 根据权利要求书46所述的电动工具，其中，
    所述第一预设电流阈值大于所述第二预设电流阈值。
  48. 根据权利要求46所述的电动工具，其中，
    所述电动工具还包括电源输入装置和整流模块；所述电源输入装置用于接入所述电动工具工作时所需的电源；所述整流模块设置为与所述电源输入装置电连接，将所述电源输入装置的电能转换成直流电供所述电动工具使用。
  49. 根据权利要求48所述的电动工具，其中，
    所述电动工具还包括供电电路和电容电路；所述供电电路与所述整流模块电连接以至少为所述控制模块供电；所述电容电路电连接在所述整流模块和所述驱动电路之间。
  50. 根据权利要求49所述的电动工具，其中，
    所述电容电路至少包括一个电解电容。
  51. 根据权利要求50所述的电动工具，其中，
    所述电解电容的容值与所述电机的额定功率之比大于20μF/kW且小于80μF/kW。
  52. 根据权利要求48所述的电动工具，其中，
    所述整流模块括由四个二极管D1、D2、D3、D4组成的整流桥。
  53. 根据权利要求书48所述的电动工具，其中，
    所述电流检测模块电连接在所述控制模块和所述电机之间；所述电流检测模块包括多个检流电阻；所述电流检测模块包括多个检流电阻。
  54. 根据权利要求书46所述的电动工具，其中，
    所述电机设置为无刷直流电机。
  55. 根据权利要求书54所述的电动工具，其中，
    所述无刷直流电机由所述驱动信号控制。
PCT/CN2022/081177 2021-05-12 2022-03-16 电动工具及其控制方法 Ceased WO2022237307A1 (zh)

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