JPH08111994A - Motor drive - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a motor drive device capable of realizing improvement in rotational position detection accuracy with a simple configuration. [Structure] The motor position detection circuit 8 uses a rotation pulse signal S
It includes a conversion unit 11 to which 1 is input, an operational amplifier circuit 12, and a transistor 15. The collector of the transistor 15 is connected to the other end of a capacitor 17, one end of which is connected to a common potential such as ground potential, and the other end is connected to a resistor 18
Is connected to the collector of the transistor 19, and the emitter of the transistor 19 is connected to the common potential. The other end of the capacitor 17 is connected to the non-inverting input section of the operational amplifier 20 and is connected to the reference potential Vth. Operational amplifier 2
The output of 0 is the set / reset flip-flop circuit 21.
Is connected to the reset input terminal of the flip-flop circuit 21, and the set input terminal of the flip-flop circuit 21 is connected to the rotation pulse signal S1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device such as a DC brushless motor.

[0002]

2. Description of the Related Art A conventional drive circuit for a three-phase DC brushless motor (hereinafter referred to as a motor) has the following configuration. The motor is provided with a total of three position detecting elements such as Hall ICs for each phase, and a position signal is obtained from each position detecting element. A PWM (pulse width modulation) signal is generated by this position signal and a speed command signal input from the outside. Here, when a total of three position detecting elements are arranged for each electrical angle of 120 °, position detecting signals having a phase difference of 120 ° in electrical angle are obtained from each position detecting element. When these position detection signals are combined to form a signal whose signal level is switched between a high level and a low level for each edge of each position detection signal, this signal corresponds to an electric angle of 60 ° of the motor. This is a signal that can detect the rotational position of the rotor of the motor with the position detection accuracy.

[0003]

On the other hand, in such a conventional motor drive device for detecting the position of a rotor, the rotor position detection accuracy is lower than the electrical angle of 60 °, and the electrical angle of the motor is the lower limit. If the angle is less than 60 °, it is difficult to perform highly accurate position detection, and in order to improve the detection accuracy, it is necessary to increase the number of the position detection elements. In this case, there is a problem in that the number of parts required for the motor drive device increases and the labor of connecting wirings, which becomes complicated accordingly, also increases.

The present invention has been made in order to solve the above-mentioned technical problem, and its purpose is to significantly improve the detection accuracy of the rotational position of a motor, and to make it simple in construction. It is to provide a drive device for a motor that can be realized by.

[0005]

A motor drive device of the present invention is a motor drive device which is driven in a plurality of phases and has a plurality of position detecting elements for detecting the position of a rotor. A rotation pulse generator that outputs a rotation pulse signal whose signal level is switched for each edge of each position detection signal from the detection element, and sets the output signal to a high level each time the rotation pulse signal is input, A variable timer unit that sets the output signal to a low level after a lapse of a specified time corresponding to the predetermined position detection accuracy of the rotor is provided, and thereby the above object can be achieved.

In the present invention, three position detecting elements may be provided.

[0007]

According to the present invention, the rotation pulse generator outputs the rotation pulse signal whose signal level is switched at each edge of each position detection signal from the plurality of position detection elements for detecting the position of the rotor. The variable timer unit sets the output signal to the high level each time the rotation pulse signal is input, and sets the output signal to the low level after a lapse of a specified time corresponding to the predetermined position detection accuracy of the rotor of the motor.

Thus, by appropriately setting the specified time, the position detection accuracy of the rotor of the motor can be arbitrarily set, and the position detection accuracy can be remarkably improved. Further, in the present invention, the improvement of the position detection accuracy can be realized without increasing the number of position detection elements, so that the configuration of the motor drive device for position detection can be simplified.

Further, in the present invention, when three position detecting elements are provided, usually three position detecting elements are arranged in a three-phase motor, so that the position detecting elements conventionally used are used as they are. You can and also in this respect
The configuration of the motor drive device can be simply configured.

[0010]

EXAMPLE A first example of the present invention will be described below.
FIG. 1 is a block diagram for explaining the electrical configuration of the motor position detection circuit 8 of the drive circuit 2 for the motor 1 according to the first embodiment of the present invention. FIG. 2 shows the electrical configuration of the drive circuit 2 for the motor 1. It is a block diagram explaining. In the present embodiment, the motor 1 is described as a three-phase full-wave brushless motor, but the present invention can be easily implemented with other types of motors. In order to detect the rotational position of the rotor 3 of the motor 1, the motor 1 is provided with, for example, three rotational position detection elements 4a, 4b, 4c that output a detection signal corresponding to the rotational position of a hall element or the like. To be

The drive circuit 2 of this embodiment includes an inverter circuit 5 including three stages of inverter transistors for supplying three-phase drive signals to the motor 1, and the position detection elements 4a and 4 described above.
a rotation pulse generator 6 that outputs a rotation pulse signal S1 that is a combination of the detection signals from b and 4c;
A motor position detection circuit 8 for generating a position detection signal S2, which will be described later, and a speed instruction signal for externally instructing the rotation speed of the motor 1 are input based on the rotation pulse signal S1 from the rotation pulse generator 6 and are separately generated. A PWM control circuit 7 for outputting a pulse width modulated control signal from the PWM (pulse width modulation) signal and the speed instruction signal, and the respective signals from the motor position detection circuit 8 and the PWM control circuit 7 are input. And a phase angle control circuit 9 for generating a phase angle control signal for turning on / off the inverter transistors of each stage of the inverter unit 5 for each phase of the motor 1. Further, the motor 1 is connected to a power source 10 for driving the motor 1.

The motor position detection circuit 8 of this embodiment receives the rotation pulse signal S1 and converts the rotation pulse signal S1 into frequency / voltage and outputs a negative logic signal.
And the signal from the conversion unit 11 is input to the non-inverting input unit,
The operational amplifier circuit 12 whose output is input to the base of the PNP transistor 15 via the resistor 23 is provided. A power supply voltage of, for example, +15 V is connected to the emitter of the transistor 15 via the resistor 16,
The other end of the capacitor 17, one end of which is connected to a common potential such as the ground potential, is connected to the collector of 5. The resistor 1
The connection point between 6 and the emitter of the transistor 15 is connected to the inverting input of the operational amplifier 22. The capacitor 17
The collector of an NPN transistor 19 is connected to the other end of the transistor via a resistor 18, and the emitter of the transistor 19 is connected to the common potential. Further, the other end of the capacitor 17 is connected to the non-inverting input section of the operational amplifier 20, and the inverting input section of the operational amplifier 20 is connected to the reference potential V.
connected to th.

The output of the operational amplifier 20 is connected to the reset input terminal of a set / reset type flip-flop circuit (hereinafter, flip-flop circuit) 21, and the set pulse input signal of the flip-flop circuit 21 is connected to the rotation pulse signal S1. To be done. The inverted output Q bar of the flip-flop circuit 21 is connected to the base of the transistor 19, and the non-inverted output Q of the flip-flop circuit 21 becomes the output of the motor position detection circuit 8.

FIG. 3 is a time chart for explaining the operation of this embodiment. The operation of this embodiment will be described below with reference to FIGS.

The rotational position of the motor 1 is detected by the position detecting elements 4a, 4b, 4c, and the position detecting element 4 is detected.
Detection signals Su, Sv, and Sw shown in FIGS. 3A to 3C are output from a, 4b, and 4c. The rotation pulse generating circuit 6 switches the signal level between a high level and a low level at each rising edge and falling edge of each of the detection signals Su, Sv, Sw based on the detection signals Su, Sv, Sw. The rotation pulse signal S1 shown in FIG. 3 (4) is generated. The rotation pulse signal S1 is input to the motor position detection circuit 8.

In the motor position detection circuit 8, the converter 11 outputs a voltage of a level corresponding to the frequency of the rotation pulse signal S1. This voltage is applied to the operational amplifier 22.
And is input to the base of the transistor 15 via the resistor 23. The operational amplifier 22 is provided for impedance matching of the output of the converter 11, and if the output impedance of the converter 11 is sufficiently low, the converter 1 is provided.
The output of 1 may be directly input to the base of the transistor 15.

Since the output from the conversion unit 11 is negative logic, if the motor 1 has a rotational speed higher than a predetermined rotational speed,
The output of the operational amplifier 22 becomes low level, and the transistor 15 is always in the conductive state. At this time, capacitor 1
7 is charged by the power supply through the transistor 15. While the potential of the capacitor 17 is lower than the reference potential Vth, a low level signal is always input to the reset input terminal of the flip-flop circuit 21, and the non-inverted output Q is shown in FIG. The output of the high level signal switched by the positive edge of the rotation pulse S1 is maintained. The inverting output Q bar is at low level, the transistor 19 is cut off, and the charging of the capacitor 17 is continued as described above.

The potential of the capacitor 17 is the reference potential Vt.
When it becomes higher than h, a high level signal is input to the reset input terminal of the flip-flop circuit 21, the non-inverted output Q becomes low level, and the inverted output Q bar becomes high level. As a result, the transistor 19 is turned on, and the electric charge charged in the capacitor 17 is discharged through the transistor 19. Due to this discharge, when the potential of the capacitor 17 becomes lower than the reference potential Vth, the transistor 19 is cut off as described above, and the charging of the capacitor 17 is started.

In this way, the position signal S2 shown in FIG. 3 (5) having a rising period determined by the time constant of the capacitance of the capacitor 17 and the resistance value of the resistor 18 is output as the output of the motor position detection circuit 8. It is input to the control circuit 9.

As described above, in this embodiment, the position detection accuracy of the rotor 3 of the motor 1 can be arbitrarily determined by appropriately selecting the capacitance or resistance value and appropriately determining the time constant. The position detection accuracy can be significantly improved. Further, in the present embodiment, the improvement of the position detection accuracy can be realized without increasing the number of the position detection elements 4a, 4b, 4c, so that the configuration of the drive device 2 of the motor 1 for performing the position detection can be simplified. can do.

Further, in this embodiment, three position detecting elements are provided as an example. Normally, three position detecting elements are arranged in the three-phase motor, so that the position detecting elements conventionally used in this embodiment can be used as they are. In this respect also, the driving device 2 for the motor 1 can be used. The configuration can be simplified.

The second embodiment of the present invention will be described below. FIG. 4 is a block diagram illustrating the electrical configuration of the motor position detection circuit 8a of the drive circuit 2 of the motor 1 according to the second embodiment of the present invention. This embodiment is similar to the motor position detection circuit 8 of the first embodiment, and the corresponding parts are designated by the same reference numerals. The configuration of the motor drive circuit in which the motor position detection circuit 8a of the present embodiment is used is the same as the configuration that was dead in the first embodiment with reference to FIG.

The motor position detection circuit 8a of this embodiment receives the rotation pulse signal S1 and receives the rotation pulse signal S1.
To a non-inverting input section, a signal from the converting section 11 is input to the non-inverting input section, and an output is negatively feedback-connected to the inverting input section; and an output section of the amplifying circuit 12. A diode 14 to which the anode is connected,
The cathode of the diode 14 is connected to the base P
It has an NP-type transistor 15 and a pull-down resistor 14 to which the cathode of a diode 14 is connected.

A resistor 16 is provided at the emitter of the transistor 15.
As an example, a power supply voltage of + 15V is connected via, and the collector of the transistor 15 is connected to the other end of the capacitor 17, one end of which is connected to a common potential such as the ground potential.
The collector of the transistor 19 is connected to the other end of the capacitor 17 via the resistor 18.
The emitter of 9 is connected to said common potential. Further, the other end of the capacitor 17 is connected to the non-inverting input section of the operational amplifier 20, and the inverting input section of the operational amplifier 20 is connected to the reference potential Vth.

The output of the operational amplifier 20 is connected to the reset input terminal of the flip-flop circuit 21, and the set input terminal of the flip-flop circuit 21 is connected to the rotation pulse signal S1. The inverted output Q bar of the flip-flop circuit 21 is connected to the base of the transistor 19, and the non-inverted output Q of the flip-flop circuit 21 becomes the output of the motor position detection circuit 8.

The time chart of FIG. 3 is also referred to in this embodiment. The operation of this embodiment will be described below with reference to FIGS. 3 and 4.

The rotation speed of the motor 1 is detected by the position detecting elements 4a, 4b, 4c, and the position detecting element 4
Detection signals Su, Sv, and Sw shown in FIGS. 3A to 3C are output from a, 4b, and 4c. The rotation pulse generating circuit 6 switches the signal level between a high level and a low level at each rising edge and falling edge of each of the detection signals Su, Sv, Sw based on the detection signals Su, Sv, Sw. The rotation pulse signal S1 shown in FIG. 3 (4) is generated. The rotation pulse signal S1 is input to the motor position detection circuit 8.

In the motor position detection circuit 8, the converter 11 outputs a voltage of a level corresponding to the frequency of the rotation pulse signal S1. This voltage is applied to the operational amplifier 12
And is input to the base of the transistor 15 via the diode 14. The operational amplifier 12 includes the conversion unit 11
It is provided for impedance matching of the output of
If the output impedance of the conversion unit 11 is sufficiently low, the output of the conversion unit 11 may be directly input to the base of the transistor 15.

Since the output from the conversion unit 11 is negative logic, if the motor 1 has a rotation speed higher than a predetermined rotation speed, the transistor 15 is always in the conductive state as described above. At this time, the capacitor 17 is charged by the power supply via the transistor 15. While the potential of the capacitor 17 is lower than the reference potential Vth, a low-level signal is always input to the reset input terminal of the flip-flop circuit 21.
The high level switched at the positive edge of the rotation pulse S1 shown in (4) is maintained. The inverting output Q bar is at low level, the transistor 19 is cut off, and the charging of the capacitor 17 is continued as described above.

The potential of the capacitor 17 is the reference potential Vt.
When it becomes higher than h, a high level signal is input to the reset input terminal of the flip-flop circuit 21, the non-inverted output Q becomes low level, and the inverted output Q bar becomes high level. As a result, the transistor 19 is turned on, and the electric charge charged in the capacitor 17 is discharged through the transistor 19. Due to this discharge, when the potential of the capacitor 17 becomes lower than the reference potential Vth, the transistor 19 is cut off as described above, and the charging of the capacitor 17 is started.

In this way, the position signal S2 shown in FIG. 3 (5) having the rising period determined by the time constant of the capacitance of the capacitor 17 and the resistance value of the resistor 18 is set.
Is output from the motor position detection circuit 8 as the control circuit 9
Is input to

Also in the present embodiment having the above-described structure and operation, the same effects as the effects described in the first embodiment can be achieved.

[0033]

As described above, according to the invention of claim 1,
By appropriately setting the prescribed time, the position detection accuracy of the rotor of the motor can be arbitrarily set, and the position detection accuracy can be significantly improved. Further, in the present invention, the improvement of the position detection accuracy can be realized without increasing the number of position detection elements, so that the configuration of the motor drive device for position detection can be simplified.

Further, in the invention of claim 2, since three position detecting elements are provided, the three position detecting elements normally provided as the position detecting elements of the three-phase motor can be used as they are, Also in this respect, the configuration of the motor drive device can be simplified. .

[Brief description of drawings]

FIG. 1 is a drive circuit 2 for a motor 1 according to a first embodiment of the present invention.
3 is a block diagram illustrating an electrical configuration of a motor position detection circuit 8 of FIG.

FIG. 2 is a block diagram illustrating an electrical configuration of a drive circuit 2 including a motor position detection circuit 8 of this embodiment.

FIG. 3 is a time chart explaining the operation of the first and second embodiments.

FIG. 4 is a motor position detection circuit 8 according to a second embodiment of the present invention.
It is a block diagram explaining the electric constitution of a.

[Explanation of symbols]

 8, 8a Motor position detection circuit 11 Conversion unit 12, 20, 22 Operational amplification circuit 15, 19 Transistor 17 Capacitor 21 Flip-flop circuit S1 Rotation pulse signal S2 Position detection signal Vth Reference potential

Claims (2)

[Claims] 1. A drive device for a motor, which is driven in a plurality of phases and includes a plurality of position detection elements for detecting the position of a rotor, wherein each position detection signal from each of the plurality of position detection elements has each edge. A rotation pulse generator that outputs a rotation pulse signal whose signal level is switched, and an output signal that is set to a high level each time the rotation pulse signal is input, and a specified time corresponding to a predetermined position detection accuracy of the rotor of the motor. And a variable timer unit that sets the output signal to a low level after a lapse of time. 2. The motor drive device according to claim 1, wherein three position detection elements are provided.