JP2006042476A - Motor drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive unit that can make a motor silent, by making a current flowing to a coil variable according to the rotating position of the motor. <P>SOLUTION: The motor drive unit comprises a rotation position signal generating circuit generating a rotation position signal that shows the rotation position of the motor, and a drive current feed circuit that feeds drive current to the coil, on the basis of the rotation position signal. The motor drive unit also comprises a control circuit that divides the voltage amplitude of the rotation position signal into a plurality of amplitudes, and makes variable the drive current that corresponds to a prescribed divided zone among the voltage amplitudes of the rotation position signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor drive device.

  As one method for driving a motor (for example, a three-phase brushless DC motor using a Hall element), PWM (Pulse Width Modulatin) control for driving a motor by intermittently supplying a drive current to a coil is known. .

  For example, a PWM-controlled motor drive device is connected in series between a power supply voltage VCC and a ground VSS as an output stage, and one end of a coil is connected to the connection point, a source transistor on the power supply voltage VCC side, and a ground VSS side And a sink transistor. The source transistor and the sink transistor are complementarily turned on / off by a predetermined pulse. When the source transistor is turned on, the power supply voltage VCC → source transistor → coil current flows. On the other hand, when the sink transistor is turned on, a current of coil → sink transistor → ground VSS flows. A drive current flows through the coil in accordance with the duty ratio of the pulse, and the motor is driven. The motor driving device using such PWM control can suppress heat generation because of low power consumption of output.

  On the other hand, in a PWM-controlled motor drive device, the drive current flowing through the coil does not change smoothly, and may change, for example, on a staircase. FIG. 8 shows an example of a driving current flowing through a coil in a conventional motor driving apparatus. The drive current becomes a point U in FIG. 8 during the period when the source transistor is on, and the point L becomes a period when the sink transistor is on. When such a rectangular drive current flows through the coil, the coil vibrates, and noise is generated when the motor is driven, for example.

In view of this, a method has been proposed in which a PWM control motor drive device smoothes changes in drive current flowing in a coil and quiets motor drive sound. (For example, see Patent Document 1)
In the conventional motor drive device, the magnitude of the sine wave signal synchronized with the rotation of the motor obtained from the Hall element attached to the periphery of the rotor, which is the rotating part of the motor, is compared with the predetermined triangular wave signal. The motor was driven by passing a drive current through the coil in accordance with the duty ratio of the pulse obtained from the magnitude comparison result. That is, the duty ratio of the pulse is controlled so that the drive current flowing in the coil is close to a sine wave obtained from the Hall element.
Japanese Patent Laid-Open No. 2002-218783

In the above-described conventional motor drive device, the duty ratio of PWM control is determined by the intersection of the sine wave waveform obtained from the Hall element and a predetermined triangular wave. For example, when there are many portions where the sine wave signal is larger than a predetermined triangular wave, the duty ratio becomes large. Conversely, when there are few portions where the sine wave signal is larger than the predetermined triangular wave, the duty ratio becomes small. For this reason, the duty ratio of PWM control is fixed depending on the rotational position of the motor, and there is a problem that the drive current flowing through the coil cannot be operated.
In addition, since the drive current flowing through the coil is fixed depending on the rotational position of the motor, there is a problem in that there is a limit to the noise reduction of the motor.

  Accordingly, an object of the present invention is to provide a motor drive device that can reduce the noise of the motor by making the drive current flowing through the coil variable according to the rotational position of the motor.

A main invention for solving the above-described problems includes a rotational position signal generation circuit that generates a rotational position signal indicating a rotational position of a motor, and a drive current supply circuit that supplies a drive current to a coil based on the rotational position signal. A control circuit that divides a plurality of voltage amplitudes of the rotational position signal and makes the driving current corresponding to a predetermined division section of the voltage amplitude of the rotational position signal variable. It is characterized by that.

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

  According to the present invention, the drive current supplied to the coil can be arbitrarily varied according to the rotational position of the motor, and the motor can be silenced.

  Hereinafter, a case where the motor driving device of the present invention is applied to a three-phase motor using a Hall element will be described.

=== Configuration of Motor Drive Device ===
FIG. 1 is a circuit block diagram showing an example of the configuration of the motor drive device of the present invention. The motor drive device of the present invention includes hall amplifiers 10, 12, and 14, a signal processing circuit 16, comparators A, B, and C ("second comparison circuit"), and a comparator Un (n = 1 to N-1). , Vn (n = 1 to N−1), Wn (n = 1 to N−1) (“first comparison circuit”), series resistors R1 to RN, the logic circuit 20, and an output circuit (“drive current”). Supply circuit]) 22, 24, 26. In addition, the part except the U-phase coil 30, the V-phase coil 32, and the W-phase coil 34 shown in FIG. 1 is integrated, for example.

The hall amplifier 10 inputs a sine wave signal synchronized with the rotation of the motor from a U-phase hall element (not shown), and outputs a signal amplified to a constant voltage amplitude.
The hall amplifier 12 inputs a sine wave signal synchronized with the rotation of the motor from a V-phase hall element (not shown), and outputs a signal amplified to a constant voltage amplitude.
The hall amplifier 14 receives a sine wave signal synchronized with the rotation of the motor from a W-phase hall element (not shown), and outputs a signal amplified to a constant voltage amplitude.
The sinusoidal signals input to the Hall amplifiers 10, 12, and 14 each have a phase difference of 120 electrical degrees.

The signal processing circuit 16 receives the output signals of the Hall amplifiers 10, 12, and 14 and outputs signals obtained by delaying the phase of the electrical angle of 30 degrees.
The signal processing circuit 16 includes an AGC circuit (not shown) that sets the voltage amplitude of the outputs of the Hall amplifiers 10, 12, and 14 to a constant amplitude of 2 × VAGC, for example.

  The voltage of the U-phase signal output from the signal processing circuit 16 is applied to the + (non-inverting input) terminal of the comparator A, and the U-phase output from the signal processing circuit 16 is applied to the − (inverting input) terminal. The midpoint voltage VAGC of the voltage amplitude of the signal is applied. Then, the comparator A outputs a rectangular signal that changes at the timing of the electrical angle of 180 degrees as a result of the comparison, to the logic circuit 20.

  The voltage of the V-phase signal output from the signal processing circuit 16 is applied to the + terminal of the comparator B, and the midpoint voltage VAGC of the V-phase voltage amplitude output from the signal processing circuit 16 is applied to the − terminal. Applied. Then, the comparator B outputs to the logic circuit 20 a rectangular signal that changes at the timing of the electrical angle of 180 degrees as a result of the comparison.

  The voltage of the W-phase signal output from the signal processing circuit 16 is applied to the + terminal of the comparator C, and the midpoint voltage of the voltage amplitude of the W-phase signal output from the signal processing circuit 16 is applied to the − terminal. VAGC is applied. Then, the comparator C outputs to the logic circuit 20 a rectangular signal that changes at the timing of the electrical angle of 180 degrees as a result of the comparison.

  The resistors R1, R2,... RN are series resistors that resistance-divide the voltage amplitude 2 × VAGC of the output signal of the signal processing circuit 16, and the resistance value and the number of N are the divided values of the output signal of the signal processing circuit 16, It is set according to the number of divisions. The resistance value of the resistor Rn (n = 1, 2,... N) is Rn (n = 1, 2,... N).

  The voltage of the U-phase signal output from the signal processing circuit 16 is applied to the + terminal of the comparator Un (n = 1, 2,... N−1), and the output from the signal processing circuit 16 is applied to the − terminal. A voltage of 2 × VAGC × {R (n + 1) +... + RN} / (R1 + R2 +... + RN) obtained by resistance-dividing the voltage amplitude of the U-phase signal is applied. Then, the comparator Un outputs the magnitude comparison result to the logic circuit 20.

  The voltage of the V-phase signal of the signal processing circuit 16 is applied to the + terminal of the comparator Vn (n = 1, 2,..., N−1), and the V output from the signal processing circuit 16 is applied to the − terminal. A voltage of 2 × VAGC × {R (n + 1) +... + RN} / (R1 + R2 +... + RN) obtained by resistance-dividing the voltage amplitude of the phase signal is applied. Then, the comparator Vn outputs the comparison result of the magnitude to the logic circuit 20.

  The voltage of the W-phase signal of the signal processing circuit 16 is applied to the + terminal of the comparator Wn (n = 1, 2,... N−1), and the W output from the signal processing circuit 16 is applied to the − terminal. A voltage of 2 × VAGC × {R (n + 1) +... + RN} / (R1 + R2 +... + RN) obtained by resistance-dividing the voltage amplitude of the phase signal is applied. The comparator Wn outputs the comparison result of the magnitude to the logic circuit 20.

  The logic circuit 20 determines a predetermined interval in the output signal of the signal processing circuit 16 according to the comparison results of the comparator Un, the comparator Vn, the comparator Wn, the comparator A, the comparator B, and the comparator C. The logic circuit 20 is preset with a duty ratio corresponding to each divided section, and the logic circuit 20 outputs the determined duty ratio of the section to the output circuits 22, 24, and 26.

  The output circuits 22, 24, and 26 operate under PWM control, and are connected in series between the power supply voltage VCC and the ground VSS as in the conventional example, and one end of the coil is connected to the connection point of the source on the power supply voltage VCC side. A transistor and a sink transistor on the ground VSS side. The source transistor and the sink transistor are turned on / off in a complementary manner. For example, the sink transistor is intermittently turned on and off according to the duty ratio of the pulse signal. A drive current corresponding to the duty ratio is supplied to the coil.

The output circuit 22 supplies a drive current to the U-phase coil 30 according to the output of the logic circuit 20.
The output circuit 24 supplies a drive current to the V-phase coil 32 according to the output of the logic circuit 20.
The output circuit 26 supplies a drive current to the W-phase coil 34 according to the output of the logic circuit 20.
The U-phase coil 30, the V-phase coil 32, and the W-phase coil 34 are wound around the stator with a star connection and an electrical phase difference of 120 degrees.

  The hall amplifiers 10, 12, and 14 and the signal processing circuit 16 constitute a rotational position signal generation circuit. The resistor RN, the comparators A, B, C, Un, Vn, Wn, and the logic circuit 20 constitute a control circuit.

=== Operation of Motor Drive Device ===
Next, the operation of the motor drive device of the present invention will be described. Since the U-phase, V-phase, and W-phase perform the same operation, the present embodiment will describe a case where a drive current is supplied to the U-phase coil 30.

  A sine wave signal synchronized with the rotation of the motor obtained from the U-phase Hall element is converted into a signal having a constant voltage amplitude by the Hall amplifier 10, and the phase of the electrical angle of 30 degrees is delayed by the signal processing circuit 16. Output as a signal.

  The voltage of the U-phase signal output from the signal processing circuit 16 is compared with the voltage appearing at the connection point of the series resistors R1 to RN by the comparator Un. At the same time, the comparator A compares the voltage with the midpoint voltage of the output signal of the signal processing circuit 16. Further, the voltages of the V-phase and W-phase signals output from the signal processing circuit 16 are compared in magnitude in the comparator B and the comparator C in the same manner as the comparator A. Then, the magnitude comparison results of the comparator Un and the comparators A, B, and C are input to the logic circuit 20. The logic circuit 20 determines a predetermined section of the output signal of the signal processing circuit 16 based on the comparison result between the comparator Un and the comparators A, B, and C, and outputs a duty ratio corresponding to the determined predetermined section to the output circuit 22. The output circuit 22 generates a drive current corresponding to the duty ratio and supplies it to the U-phase coil 30.

  FIG. 2 and FIG. 3 are diagrams for explaining an example of an operation for determining a predetermined section. The voltage of the U-phase signal output from the signal processing circuit 16 is a sine wave having a constant voltage amplitude as shown in FIG. This voltage amplitude is divided into N by the series resistors R1 to RN, and the divided voltage and the voltage of the output signal of the signal processing circuit 16 are respectively compared in magnitude by the corresponding comparator Un (n = 1 to N-1). The The logic circuit 20 determines a predetermined interval based on the comparison result of the comparator Un. For example, when the output of the comparator U1 is at a high level and the other outputs are at a low level, the section a shown in FIG. However, when only the comparison result of the comparator Un is used, one predetermined section is not determined in one cycle of the sine wave. For example, the output of the comparator Un becomes equal between the a1 interval and the a2 interval shown in FIG. 3, and the logic circuit 20 determines that the a2 interval is also the a1 interval.

  Therefore, a predetermined interval is discriminated by using the output results of the comparators A, B, and C that compare the voltage of the U-phase signal with the midpoint voltage VAGC of the voltage amplitude of the output signal of the signal processing circuit 16. To do. In FIG. 3, A is an output signal of the comparator A, B is an output signal of the comparator B, and C is an output signal of the comparator C. Since the U phase, V phase, and W phase have a phase difference of 120 degrees in the output signal of the signal processing circuit 16, the outputs of the comparators A, B, and C are also 120 degrees as shown by A, B, and C in FIG. It changes with the phase difference. For example, in the section a1 shown in FIG. 3, the output of the comparator A is high level, the output of the comparator B is low level, and the output of the comparator C is high level. On the other hand, in the section a2 shown in FIG. 3, the output of the comparator A is high level, the output of the comparator B is high level, and the output of the comparator C is low level. As described above, the a1 section and the a2 section can be discriminated based on the output results of the comparators A, B, and C.

  Therefore, the logic circuit 20 can determine, for example, a section, b section, c section, and d section shown in FIG. 2 according to the comparison result of the comparator Un and the comparison results of the comparators A, B, and C.

  In the logic circuit 20, the duty ratio of the output circuit 22 in each divided section is set in advance. For example, the duty ratio is set to 10% in the section a, the duty ratio 30% in the section b, the duty ratio 50% in the section c, and the duty ratio 80% in the section d. Then, the logic circuit 20 outputs the duty ratio set in the determined section to the output circuit 22, and the output circuit 22 causes the drive current corresponding to the duty ratio to flow through the U-phase coil 30. The duty ratio can be arbitrarily set in each of the N divided sections. With this setting, the drive current can be made variable.

  FIG. 4 is a waveform diagram showing an example of a drive current flowing in the U-phase coil 30 of the motor drive device of the present invention. In the motor driving device of the present invention, the voltage amplitude of the output signal of the signal processing circuit 16 is divided into N, and the duty ratio of each section is set so that, for example, a driving current close to a sine wave as shown by the solid line in FIG. Can be supplied. Further, it is possible to obtain a drive current as indicated by a dotted line in FIG. 4 by further changing the duty ratio. As described above, by arbitrarily setting the duty ratio of each section obtained by dividing the voltage amplitude of the output signal of the signal processing circuit 16, it is possible to manipulate the change of the drive current flowing in the U-phase coil 30, and the duty ratio The noise when driving the motor can be silenced by the operation.

  In the present embodiment, the voltage amplitude of the output signals of the Hall amplifiers 10, 12, and 14 is made constant by using the AGC circuit, but the peak hold for holding the peak value of the signal, not the AGC circuit. A circuit may be used. In this case, the voltage amplitude of the output signals of the Hall amplifiers 10, 12, and 14 is not constant, but since the peak value of the voltage amplitude is held, it may be set to divide into N according to the peak value.

  Further, the signal output from the signal processing circuit 16 is delayed in phase by 30 degrees with respect to the output of the hall amplifier 10. The drive current is supplied to the U-phase coil 30 by this 30-degree delayed signal, but the phase of the signal output from the logic circuit 20 can be advanced by setting the duty ratio of the logic circuit 20. is there. For example, when the phase is advanced 15 degrees by setting the duty ratio of the logic circuit 20, the entire motor driving apparatus is delayed by 15 degrees. It is also possible to increase the efficiency of the motor drive device by performing such phase advance operation.

=== Other Embodiments ===
FIG. 5 is a circuit block diagram for explaining a motor drive apparatus according to a second embodiment of the present invention. The motor driving apparatus shown in FIG. 5 has no sensor for detecting the position of the motor, and the present invention is applied to a sensorless motor for detecting the position of the motor based on a back electromotive force signal generated in the coil. In FIG. 5, parts having the same configuration as in FIG.

Coil voltages VU, VV, and VW having a phase difference of 120 electrical degrees are generated at one end of the U-phase coil 30, V-phase coil 32, and W-phase coil 34 by the drive current output from the output circuits 22, 24, and 26. To do.
The coil voltage VU is applied to the + terminal of the U-phase comparator 102, and the neutral point voltage VCOM is applied to the-terminal. The U-phase comparator 102 outputs a rectangular signal that changes at a timing of an electrical angle of 180 degrees by comparing the coil voltage VU with the neutral point voltage VCOM.
The coil voltage VV is applied to the + terminal of the V-phase comparator 104, and the neutral point voltage VCOM is applied to the-terminal. The V-phase comparator 104 outputs a rectangular signal that changes at a timing of an electrical angle of 180 degrees by comparing the coil voltage VV with the neutral point voltage VCOM.
The coil voltage VW is applied to the + terminal of the W-phase comparator 106, and the neutral point voltage VCOM is applied to the-terminal. The W-phase comparator 106 outputs a rectangular signal that changes at the timing of the electrical angle of 180 degrees by comparing the coil voltage VW with the neutral point voltage VCOM. Note that the rectangular signals output from the U-phase comparator 102, the V-phase comparator 104, and the W-phase comparator 106 have a phase difference of 120 electrical degrees.

The charge / discharge circuit 110 outputs a U-phase charge / discharge waveform signal in accordance with the rectangular signal output from the U-phase comparator 102.
The charge / discharge circuit 112 outputs a V-phase charge / discharge waveform signal according to the rectangular signal output from the V-phase comparator 104.
The charge / discharge circuit 114 outputs a signal indicating a W-phase charge / discharge waveform in accordance with the rectangular signal output from the W-phase comparator 106.
The signal processing circuit 116 inputs the U-phase, V-phase, and W-phase charge / discharge waveforms output from the charge / discharge circuits 110, 112, and 114, and outputs a signal obtained by delaying the phase of an electrical angle of 30 degrees. The signal processing circuit 116 also includes an AGC circuit (not shown) that makes the voltage amplitudes of the U-phase, V-phase, and W-phase charge / discharge waveforms output from the charge / discharge circuits 110, 112, and 114 constant.

Next, the configuration of the charge / discharge circuit 110 will be described.
FIG. 6 is a circuit diagram showing an example of the configuration of the charge / discharge circuit 110.
The charge / discharge circuit 110 includes PNP type bipolar transistors (hereinafter referred to as PNP transistors) 40 and 42, NPN type bipolar transistors (hereinafter referred to as NPN transistors) 46, 48 and 50, diodes 52, capacitors 54, inverters 56, constants. Current circuits I1 and I2 are provided. Note that the PNP transistors 40 and 42 and the NPN transistors 46 and 48 have the same transistor size.

  The PNP transistor 40 and the PNP transistor 42 are current-mirror connected, and the emitters of the PNP transistor 40 and the PNP transistor 42 are connected to the power supply voltage VCC. The collector of the diode-connected PNP transistor 40 is connected to the input of the constant current circuit I 1, and the collector of the PNP transistor 42 is connected to the anode of the diode 52. The output of the constant current circuit I1 is grounded (VSS). The cathode of the diode 52 is connected to the non-grounded electrode of the capacitor 54.

  The NPN transistor 46 and the NPN transistor 48 are current mirror-connected, the collector of the diode-connected NPN transistor 48 is connected to the output of the constant current circuit I2 that receives the power supply voltage VCC, and the emitter of the NPN transistor 48 is grounded. Has been. The collector of the NPN transistor 46 is connected to the non-grounded electrode of the capacitor 54 (hereinafter, this connection point is referred to as point A), and the emitter of the NPN transistor 46 is grounded.

  The collector of the NPN transistor 50 is connected to the collector of the NPN transistor 48, and the emitter is grounded. The collector of the NPN transistor 44 is connected to the collector of the PNP transistor 42, and the emitter is grounded.

  The voltage input from the U-phase comparator 102 is applied to the base of the NPN transistor 44 and also applied to the base of the NPN transistor 50 via the inverter 56. The point A is the output of the charge / discharge circuit 110.

  Next, the operation of the charge / discharge circuit 110 will be described.

<< When output of U-phase comparator 102 is high >>
Since a constant current flows through the constant current circuit I1, the collector potential of the PNP transistor 40 is lowered, and both the PNP transistors 40 and 42 connected in a current mirror are turned on. A current equal to the constant current flowing in the constant current circuit I1 flows between the emitter and collector of the PNP transistor 42. When the output of the U-phase comparator 102 is high level, the NPN transistor 44 is turned on. Since the collector of the NPN transistor 44 is connected to the anode of the diode 52, no current is supplied from the capacitor 54, and the collector current of the PNP transistor 42 flows between the collector and emitter of the NPN transistor 44.

  On the other hand, since the output of the U-phase comparator 102 becomes low level via the inverter 56, the NPN transistor 50 is turned off. Since the constant current output from the constant current circuit I2 is supplied to the collector of the NPN transistor 48, both the NPN transistor 46 and the NPN transistor 48, which are current mirror connected, are turned on. A current equal to the constant current flowing through the constant current circuit I2 flows between the collector and emitter of the NPN transistor 46. Therefore, the capacitor 54 is discharged to the ground (VSS) via the NPN transistor 46 by a current equal to the constant current flowing through the constant current circuit I2, and the voltage at the point A gradually decreases.

<< When the output of the U-phase comparator 102 is low >>
When the output of the U-phase comparator 102 is at a low level, the output of the inverter 56 is at a high level, so the NPN transistor 50 is turned on. Since the output current of the constant current circuit I2 flows between the collector and the emitter of the NPN transistor 50, both the NPN transistor 46 and the NPN transistor 48 that are current mirror connected are turned off.

  On the other hand, the PNP transistors 40 and 42 connected in a current mirror are turned on, and a current equal to the constant current flowing in the constant current circuit I1 flows between the emitter and collector of the PNP transistor 42. When the output of the U-phase comparator 102 is at a low level, the NPN transistor 44 is turned off, so that the collector current of the PNP transistor 42 is supplied to the non-grounded electrode of the capacitor 54 via the diode 52. Therefore, the capacitor 54 is charged with a current equal to the constant current flowing through the constant current circuit I1, and the voltage at the point A gradually increases.

  FIG. 7 is a diagram for explaining the relationship between the output of the U-phase comparator 102 and the charging / discharging of the capacitor 54. The level of the output of the U-phase comparator 102 switches at the timing of an electrical angle of 180 degrees. When the output of the U-phase comparator 102 is at a low level, the capacitor 54 is charged and the voltage at the point A rises. On the other hand, when the output of the U-phase comparator 102 is at a low level, the capacitor 54 is discharged, and the voltage at the point A decreases. As described above, the capacitor 54 is charged with a current equal to the constant current generated in the constant current circuit I1, and discharged with a current equal to the constant current generated in the constant current circuit I2. Therefore, the voltage amplitude of the charge / discharge waveform of the capacitor 54 can be made constant by changing the constant current flowing through the constant current circuit I1 and the constant current circuit I2 according to the voltage amplitude.

  Note that the charge / discharge circuits 112 and 114 can have the same configuration as the charge / discharge circuit 110.

  As described above, since the signal output from the signal processing circuit 116 is a triangular wave having a constant voltage amplitude, the triangular wave is divided into N as in the first embodiment of the present invention, and the duty is divided into predetermined divided sections. By setting the ratio, the drive current flowing through the U-phase coil 30, the V-phase coil 32, and the W-phase coil 34 can be manipulated.

As described above, the power supply circuit of the present invention, for example, divides the voltage amplitude of the output signal of the U-phase signal processing circuit 16 into a plurality of parts, and changes the duty ratio of each divided section to thereby change the U-phase coil. The drive current flowing through 30 can be operated according to the rotational position of the motor.
The number N of divisions and the division width when the voltage amplitude of the output signal of the signal processing circuit 16 is divided into N can be determined by setting the series resistors R1 to RN.
Further, an accurate position can be detected by discriminating the predetermined section according to the comparison result between the comparators A, B, and C and the comparator Un (n = 1 to N−1).
Furthermore, when applied to a motor drive device using PWM control, the drive current can be easily manipulated by changing the duty ratio of pulses in a predetermined section.
Further, since the voltage amplitude is constant by the AGC circuit, the position of the motor can be accurately detected when a plurality of divisions are made. Since the peak value of the output signal of the signal processing circuit 16 can be obtained by using the peak hold circuit instead of the AGC circuit, the output signal of the signal processing circuit 16 is divided according to the peak value to The position can be detected accurately.
The present invention can be effectively applied to a motor having a Hall element that detects the rotational position of the motor. However, a sensorless motor can be obtained by using a charge / discharge waveform in which a capacitor 54 is charged / discharged in accordance with a back electromotive force signal. It can also be applied to.

  As described above, the present embodiment has been specifically described based on the embodiment. However, the present embodiment is not limited to this, and various modifications can be made without departing from the scope of the present embodiment.

It is a circuit block diagram which shows the motor drive device of this invention. It is a figure for demonstrating an example of the operation | movement of discrimination | determination of a predetermined area. It is a figure for demonstrating an example of the operation | movement of discrimination | determination of a predetermined area. It is a wave form diagram which shows an example of the drive current which flows into the U-phase coil of the motor drive device of this invention. It is a circuit block diagram for demonstrating the motor drive device of 2nd Embodiment concerning this invention. It is a circuit diagram which shows an example of a structure of a charging / discharging circuit. It is a figure for demonstrating the relationship between the output of a comparator, and charging / discharging of a capacitor | condenser. It is a wave form diagram which shows an example which shows the drive current which flows into a coil in the conventional motor drive device.

Explanation of symbols

10, 12, 14 Hall amplifier 16 Signal processing circuit 20 Logic circuit 22, 24, 26 Output circuit 30 U phase coil 32 V phase coil 34 W phase coil 102 U phase comparator 104 V phase comparator 106 W phase comparator 110, 112, 114 Charge / discharge circuit

Claims (5)

In a motor drive device comprising: a rotation position signal generation circuit that generates a rotation position signal indicating a rotation position of the motor; and a drive current supply circuit that supplies a drive current to the coil based on the rotation position signal.
A control circuit that divides a plurality of voltage amplitudes of the rotational position signal and makes the driving current corresponding to a predetermined division section of the voltage amplitude of the rotational position signal variable;
A motor driving device comprising: The control circuit includes:
The motor drive circuit according to claim 1, further comprising a series resistor that divides a voltage amplitude of the rotational position signal into a plurality of parts. The control circuit includes:
A first comparison circuit for comparing the magnitude of the voltage of the rotational position signal and the voltage appearing at the connection point of the series resistor;
A second comparison circuit for comparing the magnitude of the voltage of the rotational position signal and the midpoint voltage of the voltage amplitude of the rotational position signal;
The motor drive circuit according to claim 2, wherein the predetermined division section is determined according to a comparison result of the first comparison circuit and the second comparison circuit. The drive current supply circuit includes:
Intermittently supplying the drive current to the coil;
The control circuit includes:
4. The motor drive device according to claim 1, wherein a ratio of intermittently supplying the drive current to the coil is variable in the predetermined division section. 5. A peak hold circuit for holding a peak value of the rotational position signal;
The control circuit includes:
5. The motor drive device according to claim 1, wherein the voltage amplitude of the rotational position signal is divided into a plurality of parts according to the peak value. 6.

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