JP2016025785A - Motor drive device and motor drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a power loss at the standby time of a motor in a control method of not stopping operation of a motor drive device at the standby time of the motor.SOLUTION: A full-bridge circuit 61 including a plurality of switching elements controls current to be supplied to a motor coil 71. A clock supply circuit 63 supplies a clock signal to a control circuit 62. The control circuit 62 supplies a PWM (Pulse Width Modulation) signal to each of control terminals of two switching elements for forming a current path of the motor coil 71. At the standby time of a motor, the control circuit 62 supplies PWM signals having phases reverse to each other to the control terminals of the two switching elements. The clock supply circuit 63 reduces a frequency of the clock signal for generating the PWM signals at the standby time of the motor 70.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor driving device and a motor driving system for driving a motor.

  The motor may enter a standby state even when the power is on. For example, a synchronous motor or an induction motor is usually used for an electric vehicle or a hybrid vehicle, but the motor is in a standby state at a temporary stop such as waiting for a signal. In the positioning stage apparatus in the semiconductor exposure apparatus, a linear motor is used to move the mounting table. However, when the semiconductor wafer on the mounting table is replaced, the linear motor is in a standby state.

  A full bridge circuit is widely used as a motor drive circuit. In the full bridge circuit, the direction of the current supplied to the motor coil can be changed. Further, the amount of current supplied to the motor coil can be changed by changing the duty ratio of a PWM (Pulse Width Modulation) signal for driving the switching elements constituting the full bridge circuit.

  If the operation of the full bridge circuit is stopped when the motor is on standby, it is necessary to restart the full bridge circuit when the operation of the motor is resumed. If a delay occurs in this restart, a delay also occurs in the resumption of motor operation.

  Therefore, it is conceivable to continue the switching operation of the full bridge circuit while the output current of the full bridge circuit is substantially zero during the motor standby. If the phase of the PWM signal for driving the two switching elements that form the current path of the motor coil among the plurality of switching elements constituting the full bridge circuit is reversed, the output current is substantially zero in the full bridge state. The operation of the circuit can be continued.

Japanese Unexamined Patent Publication No. 09-201092

  If the phase of the PWM signal for driving the above two switching elements is reversed when the motor is on standby, the current supply to the motor coil can be stopped, but the switching operation of these switching elements continues. Switching loss occurs.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for reducing power loss during motor standby in a control system that does not stop the operation of the motor drive device during motor standby. It is in.

  In order to solve the above-described problems, a motor driving device according to an aspect of the present invention includes a plurality of switching elements, a bridge circuit that controls a current supplied to a motor coil, and a signal to control terminals of the plurality of switching elements. A control circuit for supplying the clock signal; and a clock supply circuit for supplying a clock signal to the control circuit. The control circuit supplies a PWM signal to control terminals of two switching elements forming a current path of the motor coil. When the motor is on standby, the control circuit supplies an antiphase PWM signal to the control terminals of the two switching elements. The clock supply circuit reduces the frequency of the clock signal for generating the PWM signal when the motor is on standby.

  Another aspect of the present invention is a motor drive system. The motor drive system includes a motor drive device that drives a motor, and a power supply device that supplies power to the motor drive device. The motor driving device includes a plurality of switching elements, a bridge circuit that controls a current supplied to the motor coil, a control circuit that supplies a signal to a control terminal of the plurality of switching elements, and a clock signal to the control circuit A clock supply circuit to be supplied. The control circuit supplies a PWM signal to control terminals of two switching elements forming a current path of the motor coil. When the motor is on standby, the control circuit supplies an antiphase PWM signal to the control terminals of the two switching elements. The power supply device reduces the output voltage supplied to the motor drive device during standby of the motor.

  ADVANTAGE OF THE INVENTION According to this invention, the power loss at the time of a motor standby can be reduced by the control system which does not stop operation | movement of a motor drive device at the time of a motor standby.

It is a figure which shows the structure of the motor drive system which concerns on embodiment of this invention. It is a figure which shows the structural example of the drive device of FIG. FIGS. 3A and 3B are diagrams illustrating gate signals supplied from the control circuit to the control terminals of the first switching element to the fourth switching element when the motor is on standby. It is a figure which shows the structural example of the DC-DC converter of FIG. It is a figure which shows the structural example 1 of the PFC circuit of FIG. FIG. 3 is a diagram illustrating a configuration example 2 of the PFC circuit in FIG. 1.

  FIG. 1 is a diagram showing a configuration of a motor drive system 100 according to an embodiment of the present invention. The motor drive system 100 is a system for driving the motor 70 and includes a power supply device 20 and a drive device 60. The motor 70 is an electromagnetic motor, and the electromagnetic motor includes a stator and a mover. FIG. 1 shows an example using a motor coil 71 serving as an electromagnet as a stator and a rotor 72 including a permanent magnet as a mover. The configuration of the motor 70 is an example, and the configuration of the motor 70 is not limited as long as the motor coil is used. For example, a motor coil that serves as an electromagnet may be used for the mover, and a permanent magnet may be provided for the stator.

  The state management device 80 is a management device that manages the state of the motor 70. The state management device 80 compares a detection position signal input from a sensor (for example, a hall element) (not shown) that detects the position of the mover with a target position signal, and approaches a servo signal (hereinafter referred to as a feedback signal). Generated). The state management device 80 transmits the generated feedback signal to the driving device 60. The state management device 80 generates a standby signal and supplies it to the drive device 60 and the power supply device 20 when the motor 70 transitions to the standby state by a user operation or a setting program.

  The power supply device 20 is an AC-DC converter that converts an AC voltage supplied from an AC power source (commercial power source) 10 into a DC voltage. The power supply device 20 includes a rectifier circuit 30, a PFC circuit 40, and a DC-DC converter 50. The rectifier circuit 30 rectifies the AC voltage supplied from the AC power supply 10. The rectifier circuit 30 can be constituted by a diode bridge circuit, for example. The PFC circuit (Power Factor Correction) 40 improves the power factor of the power rectified by the rectifier circuit 30. The DC-DC converter 50 converts the DC voltage input from the PFC circuit 40 into a DC voltage having a set value. The DC-DC converter 50 supplies the converted DC voltage to the driving device 60. Configuration examples of the PFC circuit 40 and the DC-DC converter 50 will be described later.

  FIG. 2 is a diagram illustrating a configuration example of the driving device 60 of FIG. The driving device 60 is a motor driving device that receives power supplied from the power supply device 20 and drives the motor 70. The driving device 60 includes a full bridge circuit 61, a control circuit 62, and a clock supply circuit 63. The full bridge circuit 61 includes a first switching element S1 to a fourth switching element S4 and controls a current supplied to the motor coil 71.

  The full bridge circuit 61 includes a first arm in which a first switching element S1 and a second switching element S2 are connected in series between a high side reference potential and a low side reference potential, and a third switching element S3 and a fourth switching element S4. This is an H-bridge circuit configured by connecting second arms connected in series in parallel. The midpoint of the first arm is connected to one end of the motor coil 71, and the midpoint of the second arm is connected to the other end of the motor coil 71.

  In FIG. 2, an output filter 90 is inserted between the full bridge circuit 61 and the motor coil 71. The output filter 90 is an LC filter including a first inductor L1, a second inductor L2, and a first capacitor C1. By inserting the output filter 90, the rectangular wave drive signal output from the full bridge circuit 61 can be brought close to the sine wave drive signal. A configuration in which the output filter 90 is not inserted is also possible. Since the motor coil 71 also has an inductance component, a certain filtering effect occurs even if the output filter 90 is not inserted.

  MOSFETs or IGBTs can be used for the first switching element S1 to the fourth switching element S4. FIG. 2 illustrates an example in which an n-channel MOSFET is used for the first switching element S1 to the fourth switching element S4. The first switching element S1 to the fourth switching element S4 are respectively formed or connected in parallel with a first diode D1 to a fourth diode D4 that conduct in the direction from the source to the drain. Note that a p-channel MOSFET may be used for the first switching element S1 and the third switching element S3 on the high side.

  The control circuit 62 generates a gate signal to be supplied to the control terminals (gate terminals in the case of MOSFET) of the first switching element S1 to the fourth switching element S4 constituting the full bridge circuit 61. Specifically, when the motor 70 is rotated forward (or moved in the positive direction), the first switching element S1 and the fourth switching element S4 are turned on, and the second switching element S2 and the third switching element S3 are turned off. The gate signal is generated. The control circuit 62 supplies the generated gate signal to the control terminals of the first switching element S1 to the fourth switching element S4. When the motor 70 is reversely rotated (or moved in the reverse direction), a gate signal for turning off the first switching element S1 and the fourth switching element S4 and turning on the second switching element S2 and the third switching element S3 is used. Generate. The control circuit 62 supplies the generated gate signal to the control terminals of the first switching element S1 to the fourth switching element S4.

  The control circuit 62 supplies a PWM signal to the control terminals of the two switching elements that form the current path of the motor coil 71. In the present embodiment, in the state where a positive current is supplied to the motor coil 71, the first switching element S1 and the fourth switching element S4 correspond to the two switching elements. On the other hand, in the state where the reverse current is supplied to the motor coil 71, the above-described two switching elements correspond to the second switching element S2 and the third switching element S3.

  The control circuit 62 adjusts the duty ratio of the switching element during the ON period according to the feedback signal input from the state management device 80. When the position of the rotor 72 is delayed and a feedback signal instructing an increase in torque is received, the control circuit 62 increases the duty ratio and increases the amount of current supplied to the motor coil 71. On the other hand, when the position of the rotor 72 is advanced and a feedback signal instructing torque reduction is received, the control circuit 62 reduces the duty ratio to reduce the amount of current supplied to the motor coil 71.

  The clock supply circuit 63 supplies a clock signal for generating a PWM signal to the control circuit 62. The clock supply circuit 63 includes a frequency divider 64 and an oscillator 65. The oscillator 65 generates a reference clock signal. For the oscillator 65, a crystal resonator or the like is used. The frequency divider 64 divides the clock signal generated by the oscillator 65 by 1 / N to generate a clock signal to be supplied to the control circuit 62. For example, when the oscillation frequency of the oscillator 65 is 500 kHz and the switching frequency of the first switching element S1 to the fourth switching element S4 is set to 100 kHz, the frequency division ratio of the frequency divider 64 is set to 1/5.

  The control circuit 62 recognizes the standby state of the motor 70 by receiving a standby signal from the state management device 80. When the motor 70 is on standby, the control circuit 62 supplies PWM signals having opposite phases to the control terminals of the two switching elements that form the current path of the motor coil 71. When the motor 70 is on standby, the clock supply circuit 63 reduces the frequency of the clock signal for generating the PWM signal. For example, the frequency of the clock signal when the motor 70 is on standby is set to ½ of the frequency of the clock signal when the motor 70 is operating. This frequency switching process can be realized by the control circuit 62 switching the frequency division ratio of the frequency divider 64. In the above example, the frequency division ratio is switched from 1/5 to 1/10.

  FIGS. 3A and 3B are diagrams illustrating gate signals supplied from the control circuit 62 to the control terminals of the first switching element S1 to the fourth switching element S4 when the motor 70 is on standby. FIG. 3A shows a conventional gate signal, and FIG. 3B shows a gate signal according to the embodiment.

  The control circuit 62 supplies a PWM signal having a duty ratio of 50% to the control terminals of the first switching element S1 and the fourth switching element S4 that form the current path of the motor coil 71. At that time, PWM signals having opposite phases are supplied to the first switching element S1 and the fourth switching element S4, respectively. The control circuit 62 supplies a fixed low level signal as a gate signal to the control terminals of the second switching element S2 and the third switching element S3.

  As shown in FIGS. 3A and 3B, when an antiphase PWM signal is supplied to the first switching element S1 and the fourth switching element S4, the output current to the motor coil 71 can be made substantially zero. However, a ripple current is generated due to switching of the first switching element S1 and the fourth switching element S4. Even if the ripple current is removed by the output filter 90, a loss due to the ripple current is generated. Further, a recovery current flows through the second diode D2 when the first switching element S1 is turned on.

  As described above, even when the output current to the motor coil 71 is substantially zero, the switching loss due to the first switching element S1 and the fourth switching element S4 occurs. Conventionally, the switching frequency is common between the operation and standby of the motor coil 71. On the other hand, in the present embodiment, the switching frequency is lowered when the motor coil 71 is on standby. Thereby, the switching loss by 1st switching element S1 and 4th switching element S4 can be reduced. If the switching frequency is switched to ½ as shown in FIG. 3B, the switching loss can also be halved.

  If the switching frequency is greatly reduced, the switching loss can be further reduced, but the cores of the first inductor L1 and the second inductor L2 are likely to generate heat. When the switching frequency is lowered, the first inductor L1 and the second inductor L2 are likely to be magnetically saturated, and when magnetically saturated, the action as a magnetic material is lost. When the action as a magnetic material is lost, a large current flows and heat is generated. To reduce magnetic saturation, the number of windings may be increased, but the area increases. Therefore, it is necessary to maintain the switching frequency to such an extent that even the small first inductor L1 and the second inductor L2 are not magnetically saturated.

  In the present embodiment, the switching frequency is halved in consideration of reduction of switching loss, prevention of magnetic saturation of the first inductor L1 and the second inductor L2, and ease of switching the frequency division ratio of the frequency divider 64. Yes. Note that 1/2 is an example, and may be 1/4.

  In order to reduce the switching loss due to the first switching element S1 to the fourth switching element S4, there is a method of lowering the operating voltage of the full bridge circuit 61 in addition to the method of lowering the switching frequency. In order to reduce the operating voltage of the full bridge circuit 61, it is necessary to reduce the voltage output from the power supply device 20 to the driving device 60. In the present embodiment, the power supply device 20 reduces the output voltage supplied to the drive device 60 when the motor 70 is on standby. More specific description will be given below.

  FIG. 4 is a diagram illustrating a configuration example of the DC-DC converter 50 of FIG. The DC-DC converter 50 includes a full bridge circuit 51, a transformer 52, a rectifier circuit 53, a smoothing circuit 54, an output voltage detection circuit 55, a control circuit 56, and a clock supply circuit 57. The full bridge circuit 51 converts the DC voltage supplied from the PFC circuit 40 into an AC voltage and supplies it to the primary coil of the transformer 52.

  The full bridge circuit 51 includes a first arm in which a fifth switching element S5 and a sixth switching element S6 are connected in series between a high side reference potential and a low side reference potential, and a seventh switching element S7 and an eighth switching element S8. This is an H-bridge circuit configured by connecting second arms connected in series in parallel. The midpoint of the first arm is connected to one end of the primary coil of the transformer 52, and the midpoint of the second arm is connected to the other end of the primary coil of the transformer 52.

  MOSFETs or IGBTs can also be used for the fifth switching element S5 to the eighth switching element S8. The fifth switching element S5 to the eighth switching element S8 are respectively formed or connected in parallel with a fifth diode D5 to an eighth diode D8 that conduct in the direction from the source to the drain. Note that p-channel MOSFETs may be used for the high-side fifth switching element S5 and the seventh switching element S7.

  The transformer 52 includes a primary coil and a secondary coil. The transformer 52 insulates the primary side and the secondary side and transforms according to the winding ratio of the primary coil and the secondary coil. The rectifier circuit 53 rectifies the AC voltage input from the secondary coil of the transformer 52 into a DC voltage. The smoothing circuit 54 smoothes the output voltage of the rectifier circuit 53. The voltage smoothed by the smoothing circuit 54 is supplied to the driving device 60 as the output voltage of the DC-DC converter 50.

  The output voltage detection circuit 55 detects the output voltage of the DC-DC converter 50 and outputs it to the control circuit 56. The control circuit 56 generates a gate signal to be supplied to the control terminals of the fifth switching element S5 to the eighth switching element S8 constituting the full bridge circuit 51. Specifically, when a forward current is supplied to the primary coil of the transformer 52, a gate signal for turning on the fifth switching element S5 and the eighth switching element S8 and turning off the sixth switching element S6 and the seventh switching element S7. Is generated. The control circuit 56 supplies the generated gate signal to the control terminals of the fifth switching element S5 to the eighth switching element S8. When a reverse current is supplied to the primary coil of the transformer 52, a gate signal for turning off the fifth switching element S5 and the eighth switching element S8 and turning on the sixth switching element S6 and the seventh switching element S7 is generated. The control circuit 56 supplies the generated gate signal to the control terminals of the fifth switching element S5 to the eighth switching element S8.

  The control circuit 56 supplies a PWM signal to the control terminals of the two switching elements that form the current path of the primary coil of the transformer 52. The control circuit 56 adaptively changes the duty ratio of the switching element during the ON period according to the detection value from the output voltage detection circuit 55. Thereby, the output voltage of the DC-DC converter 50 is kept constant. When the output voltage of the DC-DC converter 50 is lower than the target voltage, the control circuit 56 increases the duty ratio to increase the amount of current supplied to the primary coil of the transformer 52. Conversely, when the output voltage of the DC-DC converter 50 is higher than the target voltage, the control circuit 62 decreases the duty ratio to reduce the amount of current supplied to the primary coil of the transformer 52.

  The control circuit 56 recognizes the standby state of the motor 70 by receiving a standby signal from the state management device 80. When the motor 70 is on standby, the control circuit 56 reduces the output voltage of the DC-DC converter 50 by reducing the duty ratio of the switching element during the ON period. For example, the output voltage during standby of the motor 70 is set to ½ of the output voltage during operation of the motor 70. Thereby, the switching loss of the full bridge circuit 61 of the drive device 60 can be reduced to ¼. Since the switching loss is proportional to the square of the operating voltage, the reduction in the operating voltage greatly contributes to the reduction of the switching loss.

  The clock supply circuit 57 supplies the control circuit 56 with a clock signal for generating a PWM signal. The clock supply circuit 57 includes a frequency divider 58 and an oscillator 59. The oscillator 59 may be shared with the oscillator 65 of the driving device 60. The frequency divider 58 divides the clock signal generated by the oscillator 59 or the common oscillator of the motor drive system 100 by 1 / N to generate a clock signal to be supplied to the control circuit 56.

  The clock supply circuit 57 reduces the frequency of the clock signal to be supplied to the control circuit 56 when the motor 70 is on standby. For example, the frequency of the clock signal when the motor 70 is on standby is set to ½ of the frequency of the clock signal when the motor 70 is operating. This frequency switching process can be realized by the control circuit 56 switching the frequency division ratio of the frequency divider 58.

  As described above, when the motor 70 is on standby, the switching frequency of the fifth switching element S5 to the eighth switching element S8 can be reduced by reducing the switching frequency of the fifth switching element S5 to the eighth switching element S8.

  FIG. 5 is a diagram showing a configuration example 1 of the PFC circuit 40 of FIG. A PFC circuit 40 shown in FIG. 5 is a step-up PFC circuit. The PFC circuit 40 illustrated in FIG. 5 includes a third inductor L3, a ninth switching element S9, an eleventh diode D11, a second capacitor C2, a control circuit 41, and a clock supply circuit 42. The input terminal of the third inductor L3 is connected to the high side output terminal of the rectifier circuit 30, and the output terminal of the third inductor L3 is connected to the anode terminal of the eleventh diode D11. The input terminal of the ninth switching element S9 is connected to a node between the third inductor L3 and the eleventh diode D11, and the output terminal of the ninth switching element S9 is connected to the low side output terminal of the rectifier circuit 30. The high-side terminal of the second capacitor C2 is connected to the cathode terminal of the eleventh diode D11, and the low-side terminal of the second capacitor C2 is connected to the low-side reference potential line.

  A MOSFET or IGBT can also be used for the ninth switching element S9. A ninth diode D9 conducting in the direction from the source to the drain is formed or connected in parallel to the ninth switching element S9. When the ninth switching element S9 is switched at a high frequency, the current flowing through the third inductor L3 is turned on / off at the high frequency, and the power factor is improved. At the same time, the output voltage of the PFC circuit 40 is boosted. The output voltage of the PFC circuit 40 is smoothed by the second capacitor C2 and output to the DC-DC converter 50.

  The control circuit 41 supplies a PWM signal to the control terminal of the ninth switching element S9. The control circuit 41 recognizes the standby state of the motor 70 by receiving a standby signal from the state management device 80. When the motor 70 is on standby, the control circuit 41 reduces the switching frequency of the ninth switching element S9. The clock supply circuit 42 supplies the control circuit 31 with a clock signal for generating a PWM signal. The clock supply circuit 42 includes a frequency divider 43 and an oscillator 44. The oscillator 44 may be shared with the oscillator 65 of the driving device 60 and the oscillator 59 of the DC-DC converter 50. The frequency divider 43 divides the clock signal generated by the oscillator 44 or the common oscillator of the motor drive system 100 by 1 / N to generate a clock signal to be supplied to the control circuit 41.

  The clock supply circuit 42 reduces the frequency of the clock signal to be supplied to the control circuit 41 when the motor 70 is on standby. For example, the frequency of the clock signal when the motor 70 is on standby is set to ½ of the frequency of the clock signal when the motor 70 is operating. This frequency switching process can be realized by the control circuit 41 switching the frequency dividing ratio of the frequency divider 43.

  Thus, when the motor 70 is on standby, the switching loss of the ninth switching element S9 can be reduced by reducing the switching frequency of the ninth switching element S9.

  FIG. 6 is a diagram illustrating a configuration example 2 of the PFC circuit 40 of FIG. A PFC circuit 40 shown in FIG. 6 is a step-up / step-down PFC circuit. The PFC circuit 40 shown in FIG. 6 has a configuration in which a tenth switching element S10 and a twelfth diode D12 are added to the configuration of the PFC circuit 40 shown in FIG.

  The tenth switching element S10 is inserted between the high-side output terminal of the rectifier circuit 30 and the input terminal of the third inductor L3. The cathode terminal of the twelfth diode D12 is connected to a node between the tenth switching element S10 and the third inductor L3, and the anode terminal of the twelfth diode D12 is connected to the low-side output terminal of the rectifier circuit 30. A MOSFET or IGBT can also be used for the tenth switching element S10. A tenth diode D10 that conducts in the direction from the source to the drain is formed or connected in parallel to the tenth switching element S10.

  In the PFC circuit 40 shown in FIG. 6, the tenth switching element S10, the third inductor L3, and the twelfth diode D12 constitute a step-down chopper. The second inductor L2, the ninth switching element S9, and the eleventh diode D11 constitute a boost chopper.

  The clock supply circuit 42 further includes a frequency divider 45 in addition to the frequency divider 43 and the oscillator 44. The frequency divider 43 divides the basic clock signal by 1 / N, generates a clock signal for switching the ninth switching element S9, and supplies the clock signal to the control circuit 41. The frequency divider 45 divides the basic clock signal by 1 / N, generates a clock signal for switching the tenth switching element S10, and supplies the clock signal to the control circuit 41.

  When the motor 70 is on standby, the control circuit 41 reduces the input voltage from the rectifier circuit 30 by reducing the duty ratio of the tenth switching element S10. As the duty ratio of the tenth switching element S10 is lowered, the step-down rate of the input voltage is increased. As described above, in the configuration example 2, the voltage input to the DC-DC converter 50 is lower than that in the configuration example 1.

  When the motor 70 is on standby, the operating voltage of the step-up chopper, the DC-DC converter 50 and the driving device 60 in the PFC circuit 40 can be lowered by lowering the input voltage by lowering the duty ratio of the tenth switching element S10. it can. Thereby, the switching loss of the switching element used by them can be reduced.

  As described above, according to the present embodiment, it is possible to reduce the power loss during the standby of the motor by the control method that does not stop the operation of the motor drive device during the standby of the motor. By reducing the switching frequency of the driving device 60, the switching loss in the driving device 60 can be reduced. Moreover, the switching loss in the drive device 60 can be reduced by lowering the output voltage of the DC-DC converter 50. Further, by reducing the switching frequency of the DC-DC converter 50, the switching loss in the DC-DC converter 50 can be reduced. Further, switching loss in the PFC circuit 40 can be reduced by lowering the switching frequency of the PFC circuit 40. Further, by reducing the output voltage of the PFC circuit 40, switching loss in the PFC circuit 40, the DC-DC converter 50, and the driving device 60 can be reduced.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

In the above-described embodiment, when the motor 70 is on standby,
(1) Control for reducing the switching frequency of the driving device 60;
(2) Control for reducing the output voltage of the DC-DC converter 50,
(3) Control for reducing the switching frequency of the DC-DC converter 50;
(4) Control for reducing the switching frequency of the PFC circuit 40,
(5) Control for reducing the output voltage of the PFC circuit 40,
The five controls have been described. The designer can employ any one or more of these five controls.

  Moreover, in the above-mentioned embodiment, although the system which drives the motor coil 71 by single phase alternating current was shown, you may use the system driven by three phase alternating current. In this case, a three-phase bridge circuit is used as the full bridge circuit 61 instead of an H bridge circuit. Even when the three-phase bridge circuit is used, the same as when the H-bridge circuit is used for two switching elements forming the current path of the motor coil 71 among the plurality of switching elements constituting the three-phase bridge circuit. Can apply the control.

  Moreover, although the example which uses AC power supply 10 was demonstrated in the above-mentioned embodiment, a secondary battery may be used instead of AC power supply 10. In that case, the rectifier circuit 30 and the PFC circuit 40 in the power supply device 20 are unnecessary. Even in this case, (1) control for lowering the switching frequency of the driving device 60, (2) control for lowering the output voltage of the DC-DC converter 50, and (3) control for lowering the switching frequency of the DC-DC converter 50. One or more arbitrary controls can be adopted.

  DESCRIPTION OF SYMBOLS 100 Motor drive system, 10 AC power supply, 20 Power supply device, 30 Rectifier circuit, 40 PFC circuit, 41 Control circuit, 42 Clock supply circuit, 50 DC-DC converter, 53 Rectifier circuit, 56 Control circuit, 57 Clock supply circuit, 60 Drive device, 62 control circuit, 63 clock supply circuit, 70 motor, 71 motor coil.

Claims (7)

A bridge circuit including a plurality of switching elements and controlling a current supplied to the motor coil;
A control circuit for supplying signals to control terminals of the plurality of switching elements;
A clock supply circuit for supplying a clock signal to the control circuit,
The control circuit supplies a PWM (Pulse Width Modulation) signal to control terminals of two switching elements that form a current path of the motor coil,
The control circuit supplies an antiphase PWM signal to the control terminals of the two switching elements during motor standby,
The motor drive device according to claim 1, wherein the clock supply circuit reduces the frequency of the clock signal for generating the PWM signal when the motor is on standby.   2. The motor drive according to claim 1, wherein the clock supply circuit sets the frequency of the clock signal during standby of the motor to ½ of the frequency of the clock signal during operation of the motor. apparatus. The motor drive device according to claim 1 or 2,
A power supply for supplying power to the motor drive device,
The motor drive system according to claim 1, wherein the power supply device reduces an output voltage supplied to the motor drive device during standby of the motor. The power supply device
A DC-DC converter including a switching element;
The motor drive system according to claim 3, wherein the DC-DC converter reduces a switching frequency of the switching element during standby of the motor. The power supply device
A rectifier circuit for rectifying an AC voltage supplied from an AC power supply;
A power factor correction (PFC) circuit that improves the power factor of the power rectified by the rectifier circuit and outputs the power factor to the DC-DC converter;
The motor drive system according to claim 4, wherein the PFC circuit includes a switching element, and reduces a switching frequency of the switching element when the motor is on standby.   6. The motor drive system according to claim 5, wherein the PFC circuit includes a step-up / step-down circuit, and steps down an input voltage when the motor is in a standby state and outputs the voltage to the DC-DC converter. A motor drive system comprising: a motor drive device that drives a motor; and a power supply device that supplies power to the motor drive device,
The motor driving device is
A bridge circuit including a plurality of switching elements and controlling a current supplied to the motor coil;
A control circuit for supplying signals to control terminals of the plurality of switching elements;
A clock supply circuit for supplying a clock signal to the control circuit,
The control circuit supplies a PWM (Pulse Width Modulation) signal to control terminals of two switching elements that form a current path of the motor coil,
The control circuit supplies an antiphase PWM signal to the control terminals of the two switching elements during motor standby,
The motor drive system according to claim 1, wherein the power supply device reduces an output voltage supplied to the motor drive device during standby of the motor.

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