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
  • 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
• • 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

Definitions

• the present invention refers to power supply control circuits for synchronous motors having a controller that uses one or more shunt resistors to calculate a DC current consumption of the synchronous motors.
• Synchronous motors as brushless do (BLDC) motors and permanent magnet synchronous motors (PMSM) consist of a permanent magnet which rotates (i.e. the rotor), surrounded by three equally spaced windings, which are fixed (i.e. the stator). Current flow in each winding produces a magnetic field vector, which sums with the fields from the other windings. By controlling currents in the three windings, a magnetic field of arbitrary direction and magnitude can be produced by the stator.
• BLDC motors are becoming increasingly popular in sectors such as automotive (particularly electric vehicles (EV)), heating, ventilation, and air conditioning (HVAC), in white goods and industrial goods because it does away with the mechanical brush used in traditional motors. This characteristic makes the BLDC motors more reliable and increases its service life.
• EV electric vehicles
• HVAC heating, ventilation, and air conditioning
• BLDC motor Another advantage of a BLDC motor is that it can be made smaller and lighter than a brush type motor with the same power output, making the BLDC motors suitable for applications where space is tight.
• the microcontroller of the control circuit of the synchronous motor may be configured to energize the stator coils of the motor at the correct moment bya implementing a control algorithm. Precise timing allows for accurate speed and torque control, as well as ensuring the motor runs at peak efficiency.
• the microcontroller may receive system current values as inputs and signals from position sensors (as e.g. hall sensors that indicate the position of the motor rotor) to implement the control algorithm.
• Current measurements may be used to detect when an overcurrent condition occurs allowing the system to take action to prevent a potential damage in the synchronous motor.
• current brushless DC motor control circuits may include 1 to 3 shunt resistors to measure the phase current that can be used as input for the control algorithm implemented by the microcontroller. Some algorithms may require the measurement of the DC current consumption I s I S .
• an additional shunt (101, 102) can be included either in the positive battery input (A) or in the battery return (B) (i.e. in the DC link) as shown in figure 1 that represents a conventional power supply control circuit (100) of a BLDC motor.
• the type of shunt resistors (101, 102) imply additional unwanted power consumption and heat dissipation in the system.
• the power supply control circuit (100) of figure 1 can comprise a DC source (105), an input AC filter (103), in particular a LC filter, a microcontroller/PWM block (110) that represents a pulse width modulation (PWM) generator that generates a PWM signal to a three-phase inverter (120) and a microcontroller implementing a control algorithm that controls the input current in the synchronous motor (130).
• the three-phase inverter (120) comprises six switches for high-power switching to feed current to the synchronous motor (130).
• the output from the block (110) comprises pulse width modulated (PWM) signals that determine the average voltage and average current applied to the three coils of the BLDC motor having a ⁇ ” formation as shown in figure 1 in order to control motor speed and motor torque.
• PWM pulse width modulated
• the synchronous motor (130) may use three hall-effect sensors not shown in the figure to indicate rotor position.
• the rotor itself uses several pairs of permanent magnets to generate the magnetic flux.
• figure 2 shows the control circuit (200) previously comprising means for calculating a DC current consumption I S
• the means comprises signal processing elements to obtain the DC current consumption I S of the synchronous motor (130).
• the DC current consumption I S can be used as input for the microcontroller/PWM block (210) as shown in the figure.
• These signal processing elements comprise an amplifier (405) to amplify the voltage V shunt and perform an offset correction and a low pass filter (410) to filter the voltage signal V shunt from the amplifier (405).
• an output voltage V 0 is obtained from the low pass filter (410) and the DC current consumption of the BLDC motor is obtained based on said voltage V 0 as shown in figure 2.
• a power supply control circuit for a synchronous motor that uses a procedure for measuring the input DC current consumption I S other than using shunt resistors in the DC link or extra electronic components (e.g. amplifiers, low pass filters, etc.) and thus, reducing cost and size of electronic board is desired.
• the present invention proposes synchronous motor (e.g. BLDC or PMSM motor) power supply control circuit that can measure the DC current consumption of the motor without the requirement of establishing shunt resistors in the DC link of the power supply in contrast to figure 1 and without the requirement of extra electronic components (amplifiers, low pass filters, etc.) in contrast to figure 2 reducing costs and size of the electronics board.
• synchronous motor e.g. BLDC or PMSM motor
• the power supply control circuit permits to calculate the supply input current, i.e. the DC current consumption I S of a control circuit of e.g. a three-phase brushless DC (BLDC) motor or of a Permanent Magnet Synchronous Motor (PMSM). This calculation can be entirely done by a code or software running in the microcontroller driving the power inverter of the power supply control circuit.
• BLDC three-phase brushless DC
• PMSM Permanent Magnet Synchronous Motor
• the present invention proposes an improved software algorithm used in the microcontroller without the need of adding any extra electrical component.
• the computational resources needed to run the proposed software algorithm are tiny.
• the accuracy of the DC current consumption I S calculated with the software algorithm is comparable to that of the hardware solution of figure 2.
• the power supply control circuit according to the present invention supports a single-shunt topology, wherein only one shunt resistor as shown in figure 3 is used.
• a power supply control circuit for a synchronous motor, e.g. a three-phase brushless DC, “BLDC” motor or a permanent magnet synchronous motor, “PMSM”, the power supply control circuit comprising a microcontroller generating a PWM signal having a period T and duty cycles T x , T y , T z and T w the power supply control circuit comprises a shunt resistor R shunt used for calculating the DC current consumption I S , wherein the microcontroller is configured to obtain a first current measure I 1 of the motor across the shunt resistor R shunt during T, obtain a second current measure I 2 of the motor across the shunt resistor R shunt during T and obtain Î, the average value of the current across the resistor R shunt over the period T of the PWM signal:
• the power supply control circuit is configured to perform a low-pass filtering of the average value t to obtain the DC current consumption I S .
• the power supply control circuit according to the present invention also supports a three-shunt topology that comprises three shunt resistors, one per motor phase as shown in figure 9.
• a power supply control circuit for a synchronous motor, e.g. a three-phase brushless DC, “BLDC” motor or a permanent magnet synchronous motor, “PMSM”, the synchronous motor having motor phase currents I A , I B , and I C , the power supply control circuit comprising a microcontroller generating a PWM signal having a period T and duty cycles T x , T y , T z and T w .
• the power supply control circuit comprises three shunt resistors R sh1 , R Sh2 and R Sh3 for calculating the DC current consumption I S I S .
• the present invention also supports a two-shunts topology that comprises two shunt resistors as shown in figure 10.
• a power supply control circuit for a synchronous motor, e.g. a three-phase brushless DC, “BLDC” motor or a permanent magnet synchronous motor, “PMSM”, the synchronous motor having motor phase currents I A , I B , and / C
• the power supply control circuit comprising a microcontroller generating a PWM signal having a period T and duty cycles T x , T y , T z and T w
• the power supply control circuit comprises two shunt resistors R sh1 and R sh2 used for calculating the DC current consumption I S based on a phase current signal I shunt of the synchronous motor.
• Figure 1 shows a power supply control circuit using shunt resistors in in the DC link of the power supply to measure the DC current consumption I S according to the state of the art.
• Figure 2 shows a power supply control circuit using shunt resistors for phase current sensing and extra electronic components to measure the DC current consumption (105) I S according to the state of the art.
• Figure 3 shows a power supply control circuit according to the present invention using a shunt resistor for phase current sensing to calculate the DC current consumption (105) I S .
• Figure 4 shows a PWM of the microcontroller.
• Figure 5 and 6 show current measurements during a period T.
• Figure 7 shows different duty cycles of the PWM signals.
• Figure 8 shows a low-pass filtering of the the average value of the current.
• Figure 9 shows a power supply control circuit according to the present invention using a three shunt resistors topology.
• Figure 10 shows a power supply control circuit according to the present invention using a two-shunt resistors topology.
• Figure 3 shows a power supply control circuit (300) according to the present invention using a shunt resistor (215) to calculate the DC current consumption (105) I S by the microcontroller.
• Figure 3 also shows the DC source (105) and the input AC filter (103), in particular a LC filter.
• the control circuit (300) comprises a microcontroller/PWM generator control block (310) that generates a PWM signal (shown in figure 4) for the power inverter (120) that feeds the synchronous motor (130).
• the microcontroller/PWM generator block (310) controls current in synchronous motor (130) based on the control algorithm.
• the microcontroller also implements a routine to calculate the DC current consumption (105) I S .
• the microcontroller is configured to obtain a first current measure I 1 of the motor (130) across the shunt resistor (215) R shunt during T and obtain a second current measure / 2 of the motor (130) across the shunt resistor (320) Rshunt during T.
• Figure 4 shows the PWM signals (400).
• the software in the microcontroller (310) drives the synchronous motor (130) by generating a PWM signals (400) for the power inverter (120) as shown in figure 4.
• Signals A, B and C are the PWM signals that drive the three half bridges of the power inverter (120) connected to the 3 phases of the motor (130).
• T the PWM signal
• the typical frequency of those signals is 20 kHz, but may range between 8 kHz and 25 kHz, or even a wider range depending on the characteristics of the motor and the application.
• the duty cycles T x , T y , T z and T w , of the PWM signal are shown in figure 5 and may vary from period to period T.
• Figure 5 shows the PWM signals (400), the duty cycles T x , T y , T z and T w of the PWM signals (400), the current I shunt through the shunt resistor (215) R shunt , the first current measure I 1 of the motor (130) across the shunt resistor (215) R shunt during T and the second current measure I 2 of the motor (130) across the shunt resistor (215) R shunt during T.
• the software of the microcontroller (310) uses the current of the 3 phases of the synchronous motor.
• the control circuit incorporates one shunt resistor (as shown in figure 3), three shunt resistors (as shown in figure 9) or two shunt resistors (as shown in figure 10).
• the voltage drop is proportional to the current:
• V shunt R shunt ⁇ I shunt
• the voltage drop of the shunt resistor (215) R shunt is measured twice per period T: once in the area (501) (current I 1 ) and another time in the area (502) (current / 2 ).
• the areas (501) and (502) on the left side of the period T are used over areas (501) and (502) on the right.
• An example of measurement points is displayed with circles in figure 5.
• the correspondence between the measured currents 4 and 4, and the motor phase currents I A , I B , and / C depends on the duty cycles T x , T y , T z and T w and on the pattern of the PWM signals (400).
• the controller (310) is configured to calculate: wherein Î is the average value of the across the resistor (215) R shunt over the period T of the PWM signals (400) which is represented in figure 6.
• the period and the duty cycles T x , T y , T z and T w of the PWM signals are known to the software running in the microcontroller (310). Therefore, it is possible to calculate the activation times T 1 and T 2 of the areas (501) and (502) based on the difference of duty cycles T x , T y , T z and T w such that:
• T 1 T x + T w
• T 2 T y + T z
• the PWM signals in the single- shunt topology may be non-symmetrical in some PWM periods. In these periods, the values of T z and T w may be different from T x and T y , or even they may be negative values.
• the plots in figure 7 show the exact representation of the times T x , T y , T z and T w and the cases when they should be negative.
• the software running in the microcontroller (310) has the average value Î of the current through the shunt resistor (215) at each period of the PWM signal.
• a low-pass, infinite impulse response (MR), discrete-time filter can be implemented in the software of the microcontroller (310). This filter is applied to the average values of current Î of each PWM period T. The output of this filter is the calculated input current of the power supply (105).
• a schematic representation of a low-pass filter (800) is shown in figure 8.
• the low-pass filter (800) may be an MR filter or any other type of filter, and it may be of any order (1st-order, 2nd-order, etc.).
• the low-pass filter (800) must be a low-pass filter with 0 dB gain in DC and without resonant peaks.
• the cut-off frequency of the low-pass filter (800) can be selected depending on the frequency of the PWM signals (400) and the electrical speed range of the motor (130).
• the cut-off frequency of the low-pass filter (800) may be smaller than those other frequencies. For example, for a PWM signal with frequency of 20 kHz and the electrical speed of the motor between 45 and 370 electrical revolutions per second, the cut-off frequency of the low-pass filter (800) may be set to 15 Hz.
• FIG. 9 shows the power supply control circuit (300) for the motor (130).
• the advantages of the configuration of the power supply control circuit (300) are that this configuration can obtain more precise phase currents readings and involve less acoustic noise and less total harmonic distortion (THD).
• the power supply control circuit (300) comprises the microcontroller/PWM generator control block (310) that generates six PWM signals for the power inverter (120) that feeds the synchronous motor (130).
• the microcontroller/PWM generator block (310) controls current in the synchronous motor (130) based on a control algorithm.
• the control circuit (300) calculates the DC current consumption I S based on phase current signals.
• I Shunt The power supply control circuit (300) comprises three shunt resistors R sh1 , R sh2 and R sh3 for measuring each phase current.
• the microcontroller (310) is configured to obtain a phase current measure I shunt1 of the synchronous motor (130) across the shunt resistor (315) R sh1 , obtain a phase current measure I shunt 2 of the motor (130) across the shunt resistor (320) R sh2 , and obtain a phase current measure I shunt3 of the motor (130) across the shunt resistor (325) R sh3 .
• the currents of the phases of the motor are sampled at the beginning of the PWM period T as shown in figure 11.
• the sample point with three shunts may be placed in the middle of the PWM period.
• I shunt1 I A
• I shunt 2 I B
• I shunt3 / C .
• the microcontroller (310) is configured to calculate: wherein Î is the average value of the current across the three shunt resistors (315, 320, 325) R sh1 , R sh2 and R sh3 over the period T of the PWM signal (400). Finally, a low-pass filtering of the average value Î to obtain the DC current consumption (105) I S is performed similarly to the single-shunt topology.
• 2-shunt topology 2-shunt topology:
• FIG 10 shows the power supply control circuit (300) for the motor (130).
• the control circuit (300) calculates the DC current consumption I S based on phase current signals.
• I Shunt The power supply control circuit (300) comprises two shunt resistors R sh1 and R sh2 for measuring each phase current.
• the currents of the phases of the motor are sampled at the beginning of the PWM period T as shown in figure 11.
• the sample point with two shunts may be placed in the middle of the PWM period.
• the microcontroller (310) calculates: wherein Î is the average value of the current across the two shunt resistors (315, 320) R Shi and R sh2 over the period T of the PWM signal (400).

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• Power Engineering (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)

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• 2021
  • 2021-01-14 WO PCT/EP2021/050725 patent/WO2021148308A1/en not_active Ceased
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  • 2021-01-14 CN CN202180010584.9A patent/CN114982124A/zh active Pending

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