JP2012210111A - Motor drive power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive power supply circuit which suppresses start-up failure of a motor and motor stop during driving a motor when driving a DC sensorless brushless motor in a power supply configuration of constant current control.SOLUTION: A motor drive power supply circuit comprises: a step-down chopper type power supply 6; a motor drive unit 2 which includes an inverter circuit driving a DC sensorless brushless motor; a load current detection unit 7 which detects current flowing in the motor drive unit 2; an output current detection unit 8 which operates in response to detection value of the load current detection unit 7; an output feedback unit 10 which feeds back output status in response to behavior of the output current detection unit 8; a reference voltage generation unit 11; a comparator 14; an output voltage clamp unit 9; and an output feedback selector unit 15 which switches operation of the output feedback unit 10 between the output current detection unit 8 and the output voltage clamp unit 9 in response to an output voltage value.

Description

  The present invention relates to a power supply circuit for driving a sensorless DC brushless motor of an electrical device such as a ventilation device that mounts a sensorless DC brushless motor and drives a fan to blow air.

  As a method for controlling the DC brushless motor, a control method for controlling the DC brushless motor by constant current control is known because the circuit configuration is simple and torque ripple is small (see, for example, Patent Document 1). . Also, without using a position sensor for detecting the rotational position of the DC brushless motor, the current flowing through the inverter circuit that drives the DC brushless motor is detected with high accuracy, and the rotational position of the DC brushless motor is detected from the detected current value. Thus, a sensorless DC brushless motor driving method for driving a DC brushless motor is known (see, for example, Patent Document 2).

JP 2005-117815 A JP 2002-101690 A

  In general, a DC sensorless brushless motor is driven by a motor drive unit equipped with an inverter circuit, after direct current excitation is performed on a predetermined phase and the rotor position of the motor is fixed, and then a predetermined energization switching is performed on each phase. Forced commutation to rotate the motor automatically, estimate the position of the motor based on the induced voltage of the winding of each phase generated by the rotation of the motor, then start by driving to synchronous operation and drive . Also, if the induced voltage cannot be detected normally when starting or driving the motor, stop the motor drive and start again, and repeat the startup operation several times until the motor is driven normally. Estimate the motor position and switch to synchronous operation.

  In order to reduce the torque ripple and torque variation of a DC sensorless brushless motor and suppress the generation of noise and vibration, the motor starts from DC excitation to forced commutation when driving the motor with a constant current control power supply configuration. Sometimes it is impossible to secure the starting current required for constant current control, the rotor cannot be accurately fixed, or the required torque cannot be supplied during forced commutation, the motor position cannot be estimated, and the motor cannot be started. There is. Also, if the motor load (for example, a fan) suddenly changes during motor rotation and the load becomes light, with the constant current control power supply configuration, the output voltage decreases and the lower limit of the minimum operating voltage of the inverter circuit of the motor drive unit There is a problem that the motor stops.

  The present invention solves the above-described problem. When a DC sensorless brushless motor is driven with a constant current control power supply configuration, a motor drive power supply circuit that suppresses motor start-up failure and motor stoppage during motor drive is provided. It is intended to provide.

  In order to solve the above problems, a motor drive power supply circuit according to the present invention detects a current flowing in a motor drive unit, a motor drive unit including a step-down chopper type power supply unit, an inverter circuit that drives a DC sensorless brushless motor, and the like. Load current detection unit, output current detection unit that generates a voltage value according to the detection value of the load current detection unit, and fixed output voltage that generates a voltage value set higher than the minimum operating voltage of the motor drive unit And the voltage value of the output current detection unit as a first signal, the voltage value is fed back to the step-down chopper power supply unit, and the voltage value generated by the output fixing unit is fed back as a second signal. DC sensorless brush that controls the output voltage of the step-down chopper type power supply unit so that the load current value flowing through the load current detection unit is constant A motor drive power supply circuit, which generates a reference voltage having a voltage value lower than the output voltage from the output voltage; and the output voltage is higher than a minimum operating voltage of the motor drive unit A divided voltage generation unit that generates the output voltage into a voltage divided by a voltage dividing resistor so that the voltage value becomes the same voltage value as the reference voltage when the voltage is reached, and compares the divided voltage with the reference voltage And an output feedback switching unit that switches the feedback signal of the output feedback unit to one of the first signal and the second signal according to the output signal of the comparison unit. It achieves the desired purpose.

  According to the present invention, a step-down chopper type power supply unit, a motor drive unit including an inverter circuit that drives a DC sensorless brushless motor, a load current detection unit that detects a current flowing in the motor drive unit, and a load current detection unit An output current detection unit that generates a voltage value according to the detection value, an output voltage fixing unit that generates a voltage value set to a voltage value higher than the minimum operating voltage of the motor drive unit, and a voltage value of the output current detection unit The voltage value is fed back to the step-down chopper type power supply unit as a first signal and the voltage value generated by the output fixing unit is fed back as a second signal to the load current detection unit. A power supply circuit for driving a DC sensorless brushless motor that controls an output voltage of a step-down chopper type power supply unit so that a flowing load current value becomes constant. A reference voltage generation unit that generates a reference voltage having a voltage value lower than the output voltage from the voltage, and the same voltage as the reference voltage when the output voltage is higher than the lowest operating voltage of the motor drive unit A divided voltage generating unit that generates a voltage obtained by dividing the output voltage by a voltage dividing resistor so as to be a value, a comparing unit that compares the divided voltage and the reference voltage, and an output signal of the comparing unit The output voltage output from the step-down chopper type power supply unit by including the output feedback switching unit that switches the feedback signal of the output feedback unit to one of the first signal and the second signal. And the reference voltage generated by the reference voltage generation unit is calculated by the comparison unit, and the output feedback switching unit is operated to obtain the first signal of the load current detection unit and the second signal of the output voltage fixing unit. Switch output By operating the unit, the output state of the step-down chopper type power supply unit is switched between constant current control and constant voltage control to supply power to the motor drive unit. When the output voltage at the start of the DC sensorless brushless motor is lower than the reference voltage, the second signal is fed back and low voltage control is performed to ensure the necessary torque at the time of DC excitation and forced commutation. When the failure is suppressed and the constant voltage control is performed by feeding back the first signal when the output voltage becomes higher than the reference voltage, and the load becomes light and the output voltage drops below the reference voltage Because the motor is driven again by constant voltage control, a motor drive power supply circuit that can suppress unintentional stop and restart due to motor load fluctuations. Can be provided.

1 is a block diagram of a motor drive power supply circuit according to a first embodiment of the present invention. Block diagram of a motor drive power supply circuit describing details of the comparator of the circuit Block diagram of a motor drive power supply circuit according to a second embodiment of the present invention Block diagram of a motor drive power supply circuit according to a third embodiment of the present invention The block diagram of the power supply circuit for a motor drive which described the detail of the comparison part of Embodiment 4 of this invention, and a comparison discharge part

  The invention of the power supply circuit for driving the motor according to claim 1 of the present invention detects a current flowing through the motor drive unit, a motor drive unit having a step-down chopper type power supply unit, an inverter circuit for driving a DC sensorless brushless motor, and the like. Load current detection unit, output current detection unit that generates a voltage value according to the detection value of the load current detection unit, and fixed output voltage that generates a voltage value set higher than the minimum operating voltage of the motor drive unit And the voltage value of the output current detection unit as a first signal, the voltage value is fed back to the step-down chopper power supply unit, and the voltage value generated by the output fixing unit is fed back as a second signal. DC sensorless brushless that controls the output voltage of the step-down chopper type power supply unit so that the load current value flowing through the load current detection unit is constant A power supply circuit for driving a motor, wherein a reference voltage generating unit generates a reference voltage having a voltage value lower than the output voltage from the output voltage, and the output voltage is higher than a minimum operating voltage of the motor driving unit. The divided voltage generation unit that generates the output voltage into a voltage obtained by dividing the output voltage using a voltage dividing resistor so that the voltage value becomes the same as the reference voltage when the current value becomes, and the divided voltage and the reference voltage are compared. And an output feedback switching unit that switches the feedback signal of the output feedback unit to one of the first signal and the second signal according to the output signal of the comparison unit.

  Thus, the output voltage output from the step-down chopper type power supply unit and the reference voltage generated by the reference voltage generation unit are calculated by the comparison unit, and the output feedback switching unit is operated to operate the first of the load current detection unit. The output state of the step-down chopper type power supply unit is switched between constant current control and constant voltage control by switching the signal of the output signal and the second signal of the output voltage fixing unit and operating the output feedback unit. In order to supply power, the output feedback unit performs low-voltage control by feeding back the second signal when the output voltage at the start of the DC sensorless brushless motor is lower than the reference voltage according to the comparison result of the comparison unit, and performs DC excitation. The torque required for forced commutation can be ensured, and motor start-up failure can be suppressed, and when the output voltage becomes higher than the reference voltage, the first signal is fed back to provide constant current. When the load becomes light and the output voltage drops below the reference voltage, the motor is driven again by constant voltage control, and an unintentional stop or restart due to motor load fluctuations. A motor drive power supply circuit that can be suppressed can be provided.

  According to a second aspect of the present invention, the motor drive power supply circuit includes an initial charging unit in parallel with the output voltage fixing unit.

  As a result, when the power is supplied to the step-down chopper type power supply unit and the initial output voltage value determined by the switching frequency and the inductance of the step-down chopper type power supply unit is output, the reference voltage generation unit During the time until the comparator operates stably, the operation of the output feedback switching unit is unstable (for example, when the initial output voltage is low and the reference voltage is lower than the set reference voltage, the minimum operating voltage of the comparator is maintained) In some cases, the output of the comparison unit becomes unstable because the initial charging unit is provided in parallel with the output voltage fixing unit and the output feedback switching unit does not operate. By operating the feedback unit with the initial charging unit, the output state is normally returned to the step-down chopper type power supply unit, so the output of the step-down chopper type power supply unit is stable and the motor is driven. It can provide stable power circuit for motor drive that can supply power to.

  According to a third aspect of the present invention, the reference voltage generated by the reference voltage generating unit is set to be equal to or lower than the minimum operating voltage value of the motor driving unit and equal to or higher than the minimum operating voltage of the comparing unit.

  Thus, when the DC sensorless brushless motor is driven by constant current control, the output voltage of the step-down chopper type power supply unit is increased or decreased according to the load so that the current value of the load current detection unit becomes constant. When the voltage is set higher, the output voltage width that can control the motor with constant current control is used to switch from constant current control to constant voltage control at the output feedback switching unit when the output voltage becomes lower than the set reference voltage. As a result, the motor control load range becomes narrower. On the other hand, if the reference voltage is set low, the voltage will be lower than the minimum operating voltage of the inverter circuit provided in the motor drive unit and the motor will not be able to drive, and if it is lower than the minimum operating voltage of the comparison unit, the comparison unit will not operate normally. Therefore, the output feedback switching unit cannot be controlled as intended. Therefore, by setting a reference voltage that is equal to or higher than the minimum operating voltage value of the inverter circuit of the motor drive unit and higher than the minimum operating voltage of the comparison unit, power can be stably supplied to the motor drive unit without narrowing the motor control load range. Can be provided.

  According to a fourth aspect of the present invention, the output feedback switching unit includes two or more semiconductor switches that operate in conflict with each other by the same input signal.

  Thus, by using complementary semiconductor switches (for example, PNP transistor and NPN transistor) as the changeover switch of the output feedback switching unit, the output voltage fixing unit and the output current detecting unit are obtained by one output signal output from the comparison unit. In addition, the output feedback unit can be operated by switching the output, and a power supply circuit for driving the motor with a simplified circuit can be provided.

  According to a fifth aspect of the present invention, there is provided a motor driving power supply circuit comprising a reference voltage charging section charged with a reference voltage in a reference voltage input section of a comparison section for comparing an output voltage with a reference voltage.

  As a result, the rise in the input voltage value of the reference voltage input to the comparator can be delayed, so that when the motor is started, the output voltage fixing unit is set for a predetermined period according to the time constant set in the reference voltage charging unit. After the operation, the output voltage divided above the minimum operating voltage value of the motor drive unit is compared with the voltage charged by the reference voltage charging unit, and the output feedback switching unit according to the calculated output value of the comparator By operating the output feedback unit by the output current detection unit, the constant voltage control can be switched to the constant current control, and the motor can be started stably. In addition, when starting the motor, the motor can be driven at a low speed by constant voltage control with a voltage setting value slightly higher than the minimum operating voltage of the motor drive unit, and then driven by a predetermined current value by constant current control. Therefore, the motor can be driven at a low speed for a predetermined period at the time of starting the motor, and then the motor can be driven at a predetermined current value, so that two speeds can be provided at the time of starting. Furthermore, the torque generated at motor startup is minimized by driving the motor at a constant voltage with a voltage that is set to a voltage value slightly higher than the minimum operating voltage of the motor drive unit at the output voltage fixing unit. Since it can be suppressed, it is possible to suppress noise and vibration generated by the generation of steep torque when the motor is driven when the motor is started.

  According to a sixth aspect of the present invention, the motor drive power supply circuit is configured to supply the drive voltage of the comparison section from the reference voltage.

  As a result, when the load on the motor becomes light and the output voltage of the step-down chopper power supply drops, or the motor locks, the motor position cannot be detected from the induced voltage, and the motor drive restarts. When the output voltage of the step-down chopper type power supply unit drops during DC excitation or forced commutation, by supplying the drive voltage of the comparison unit that compares the output voltage and the reference voltage from the reference voltage generated from the output voltage, An output feedback switching unit can be controlled without being influenced by fluctuations in the output voltage, and a motor drive power supply circuit that can stably control unintentional stop and restart due to motor load fluctuations can be provided.

  Further, the invention of the power supply circuit for driving the motor according to claim 7 includes a comparison discharge unit that compares the output voltage of the step-down chopper type power supply unit and the reference voltage, and when the output voltage is lower than the reference voltage, The initial charging unit is configured to be discharged.

  As a result, the motor load becomes light and the output voltage output from the step-down chopper type power supply unit decreases, and the output feedback switching unit is operated by the comparison unit to switch between the output current detection unit and the output voltage fixing unit. When switching from constant current control to operate the output feedback unit to constant voltage control, the operation of the output feedback switching unit is unstable (for example, the motor load is light and the output voltage is held near the reference voltage. If the output of the comparison unit becomes unstable due to an event that the output of the comparison unit is switched due to a disturbance, the output feedback unit does not depend on the operation of the output feedback switching unit. Because the output state is normally fed back to the step-down chopper type power supply unit by operating the initial charging unit, the output of the step-down chopper type power supply unit is stable, and power can be supplied stably to the motor drive unit.Also, when the motor is locked and stopped, the induced voltage cannot be detected normally by the motor drive unit, and the motor drive unit temporarily stops and restarts. During direct current excitation or forced commutation, a large amount of current flows through the load current detector and the output voltage of the step-down chopper power supply decreases. Since an event that the output voltage fluctuates due to the generation of power, the initial charging unit is temporarily discharged by comparing the output voltage and the reference voltage, and the output feedback unit is operated by the initial charging unit, When the output state is normally fed back to the step-down chopper type power supply unit, the output of the step-down chopper type power supply unit is stabilized, and the motor is unlocked, the motor can be restarted normally. It can provide Ta driving power supply circuit.

  Further, the invention of the power supply circuit for driving the motor according to claim 8 includes a comparison discharge unit that compares the output voltage of the step-down chopper type power supply unit and the reference voltage, and when the output voltage is lower than the reference voltage, The reference voltage charging unit is configured to be discharged.

  As a result, when the motor load becomes light and the output voltage drops, or when the motor locks and stops due to some event, the output voltage is compared with the reference voltage to temporarily discharge the reference voltage charging unit. After the output fixing unit is operated for a predetermined period of time by recharging the output voltage, the output voltage is compared with the voltage charged in the reference voltage charging unit, and the output feedback is switched according to the operation output value of the comparator. Since the output current detection unit can be operated to switch to constant current control by operating the output current detection unit, the motor can be started stably. In addition, when the motor is restarted in the same way as when the motor is started, after the motor is driven at a low speed by constant voltage control, it can be driven by a predetermined current value by constant current control. Depending on the motor drive, the motor can be driven at a low speed for a predetermined period at the start of the motor, and then the motor can be driven at a predetermined current value. Power supply circuit can be provided.

  Further, the invention of the power supply circuit for driving the motor according to claim 9 uses the same initial charging unit and reference voltage charging unit by using one semiconductor element when the output voltage is lower than the reference voltage by the comparative discharge unit. It is comprised so that it discharges by this comparative discharge part.

  This simplifies the circuit configuration and discharges the initial charging unit and the reference voltage charging unit with a single comparative discharge unit when the motor is restarted or locked, thereby stabilizing unintentional stopping and restarting due to motor load fluctuations. Thus, it is possible to provide a motor drive power supply circuit that can be controlled in a controlled manner.

  According to a tenth aspect of the present invention, there is provided a motor drive power supply circuit comprising hysteresis in the comparison section.

  As a result, the output feedback switching unit can be switched with a time constant when the output feedback switching unit is switched, so that the light load state of the motor load is continued and the step-down chopper power supply with the output voltage close to the reference voltage When the constant current control is performed by the unit, the output voltage falls below the reference voltage due to a slight disturbance, and is calculated by the comparison unit to operate the output feedback switching unit, so that the constant current control is switched to the constant voltage control. After that, although the current load shifts to the constant current control, the light load state of the motor load is continued, so that it is switched to the constant voltage control again due to a slight disturbance. Noise and vibration due to torque ripple generated by the difference in motor output torque that occurs when control and constant voltage control are repeated It can be provided to suppress motor drive power supply circuit.

  The motor drive power supply circuit according to claim 11 is configured such that the comparative discharge section is provided with hysteresis.

  As a result, the output feedback switching unit can be switched with a time constant when the output feedback switching unit is switched, so that the light load state of the motor load is continued and the step-down chopper power supply with the output voltage close to the reference voltage When the constant current control is performed by the unit, the output voltage falls below the reference voltage due to a slight disturbance, and is calculated by the comparison unit to operate the output feedback switching unit, so that the constant current control is switched to the constant voltage control. After that, although the current load shifts to the constant current control, the light load state of the motor load is continued, so that it is switched to the constant voltage control again due to a slight disturbance. Noise and vibration due to torque ripple generated by the difference in motor output torque that occurs when control and constant voltage control are repeated It can be provided to suppress motor drive power supply circuit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram of a DC sensorless brushless motor drive power supply circuit according to Embodiment 1 of the present invention. FIG. 2 is a block diagram of a motor drive power supply circuit describing details of the comparison unit of the circuit.

  The DC sensorless brushless motor driving power supply circuit of the present embodiment, as shown in FIG. 1, is an inverter circuit (not shown) that drives a DC sensorless brushless motor (hereinafter referred to as motor 1). The motor drive power supply circuit 3 that supplies electric power to the motor drive unit 2 having FETs and three arms is smoothed by the rectifying and smoothing unit 5 directly connected to the commercial power source 4 and the rectifying and smoothing unit 5 A step-down chopper type power supply unit 6 that steps down the generated voltage to a predetermined voltage value (not shown, for example, a gate driving circuit that drives the FET and the gate of the FET, an inductance connected to the source of the FET, It is composed of a flywheel diode and an electrolytic capacitor for smoothing the output voltage.) And an inverter circuit built in the motor drive unit 2 A load current detector 7 for detecting a flowing load current, an output current detector 8 for generating a voltage value corresponding to the detected value of the load current, and a voltage set to a voltage value higher than the minimum operating voltage of the motor drive unit 2 The voltage value generated by the output voltage fixing unit 9 and the voltage value generated by the output voltage fixing unit 9 are fed back to the step-down chopper power supply unit 6 using the voltage value of the output voltage fixing unit 9 for generating a value and the voltage value of the output current detection unit 8 as a first signal. And an output feedback unit 10 (for example, a photocoupler) that feeds back as a second signal, and controls the output voltage of the step-down chopper type power supply unit so that the load current value flowing through the load current detection unit is constant It is.

  Further, a reference voltage generation unit 11 (for example, a low saturation linear regulator or a step-down chopper circuit) that generates a reference voltage having a voltage value lower than the output voltage from the output voltage of the step-down chopper type power supply unit 6; A divided voltage generated by dividing the output voltage by the voltage dividing resistor 12 so that the output voltage becomes the same voltage value as the reference voltage when the output voltage becomes higher than the minimum operating voltage of the motor drive unit. A generator 13, a comparison unit 14 (for example, a comparator) that compares the reference voltage with a voltage obtained by dividing the output voltage by the voltage dividing resistor 12, and a feedback signal of an output feedback unit based on an output signal of the comparison unit 14 Output feedback switching unit 15 (for example, composed of two complementary transistors) for switching to one of the first signal and the second signal It is those with a.

  Further, in the present embodiment, as shown in FIG. 2, the reference voltage generated by the reference voltage generator 11 is not directly input to the input unit of the comparator 14, but is charged by this reference voltage. 16 is input.

  In the above configuration, power is applied to the step-down chopper type power supply unit 6 and a predetermined initial output voltage of the step-down chopper type power supply unit 6 (a predetermined initial output voltage determined by the switching frequency and inductance of the step-down chopper circuit) is output. In this case, the reference voltage generator 11 compares the output voltage from the output voltage lower than the lowest operating voltage of the motor driver 2 (for example, defined by the lowest gate drive voltage of the FET built in the inverter circuit). A voltage greater than the minimum operating voltage of the device is generated. The non-inverting amplification terminal of the comparator of the comparison unit 14 has an output voltage that is higher than the lowest operating voltage of the motor driving unit 2 (for example, a voltage value that is 10% higher than the lowest operating voltage of the motor driving unit 2). In this case, the voltage divided by the voltage dividing resistor 12 is input so that the same voltage as the reference voltage is input (constituted with a Zener diode in parallel for protecting the non-inverting input terminal) The voltage of the reference voltage charging unit 16 charged in a capacitor (for example, an electrolytic capacitor) is input to the amplification terminal via a resistor by a reference voltage. Therefore, during the initial output voltage, High is output from the comparison unit 14, the first semiconductor switch 17 (for example, the PNP transistor) of the output current detection unit 8 of the output feedback switching unit 15 is in a non-conductive state, and the output voltage fixing unit Since the 9th second semiconductor switch 18 (for example, NPN transistor) is in the conductive state, the output voltage fixing unit 9 operates to feed back the second signal and operate the output feedback unit 10. Therefore, the output voltage output from the step-down chopper type power supply unit 6 is a predetermined voltage set to a voltage value slightly higher than the minimum operating voltage of the motor driving unit 2 by the output fixing unit (for example, the lowest voltage of the motor driving unit 2). The voltage is 10% higher than the operating voltage), and the motor 1 is driven by constant voltage control. Thereafter, when the voltage of the reference voltage charging unit 16 becomes equal to or higher than the voltage input to the non-inverting amplifier terminal, the comparison unit 14 outputs Low. At this time, since the first semiconductor switch 17 of the output feedback switching unit 15 is switched to the conductive state and the second semiconductor switch 18 is switched to the non-conductive state, the output current detection unit 8 operates to feed back the first signal. Thus, the output feedback unit 10 is controlled, and the step-down chopper type power supply unit 6 shifts to constant current control for controlling the output voltage so that the current flowing through the load current detection unit 7 becomes constant.

  Further, when the load of the motor 1 is light during normal operation, if the step-down chopper type power supply unit 6 controls the output voltage by constant current control, the output voltage is the current flowing through the load current detection unit 7. Is controlled to be constant, the output voltage decreases. When the output voltage is slightly lower than the lowest operating voltage of the motor drive unit 2, the voltage input to the non-inverting input terminal of the comparison unit 14 is lower than the reference voltage, so that the output feedback switching unit 15 Since the first semiconductor switch 17 is switched from the conductive state to the non-conductive state, and the second semiconductor switch 18 is switched from the non-conductive state to the conductive state, the output voltage fixing unit 9 operates to feed back the second signal. Thus, the output feedback unit 10 is controlled, and a predetermined constant voltage set by the output voltage fixing unit 9 is applied to the motor 1 as the output voltage of the step-down chopper type power supply unit 6. Thereafter, when the load state of the motor 1 returns to the normal state, the output state of the step-down chopper power supply unit 6 is switched from constant voltage control to constant current control as described above.

  In addition, when the motor 1 is locked (for example, contact of a foreign object), no induced voltage is generated when the motor 1 is locked by the motor driving unit 2, so that the synchronous operation is temporarily stopped and restarted. carry out. At that time, since the motor 1 is temporarily stopped, the load of the motor 1 becomes light load and the output voltage decreases rapidly. However, as in the case where the load of the motor 1 becomes light load, the constant current control is performed. When the control shifts to voltage control and the lock of the motor 1 is released, the motor 1 can be driven normally.

  Here, the reference voltage generated by the reference voltage generating unit 11 is set to be equal to or lower than the minimum operating voltage value of the motor driving unit 2 and higher than the minimum operating voltage of the comparing unit 14. When the motor 1 is driven by constant current control, the output voltage of the step-down chopper type power supply unit 6 is increased or decreased according to the load so that the current value of the load current detection unit 7 is constant, so that the reference voltage is increased. When set, when the output voltage becomes lower than the set reference voltage, the output feedback switching unit 15 switches from constant current control to constant voltage control, so that the output voltage width that can control the motor 1 by constant current control is narrow. Therefore, the control load range of the motor 1 is also narrowed. On the other hand, if the reference voltage is set low, the motor 1 becomes lower than the minimum operating voltage of the inverter circuit provided in the motor driving unit 2 and the motor 1 cannot be driven. The output feedback switching unit 15 cannot be controlled as intended without operating. Therefore, by setting a reference voltage that is equal to or higher than the minimum operating voltage value of the motor driving unit 2 and higher than the minimum operating voltage of the comparing unit 14, the motor driving unit 2 can be stably controlled without narrowing the control load range of the motor 1. Electric power can be supplied.

  Note that the operation voltage of the comparison unit 14 supplied to the comparison unit 14 is configured to be supplied from a reference voltage, and the output voltage of the step-down chopper type power supply unit 6 is reduced because the motor load is light. Or, the motor 1 is locked, and the position of the motor 1 cannot be detected from the induced voltage of the motor. The motor driving unit 2 is restarted, and the output of the step-down chopper type power supply unit 6 at the time of DC excitation or forced commutation. Even when the voltage drops, by supplying the driving voltage of the comparison unit 14 that compares the output voltage and the reference voltage from the reference voltage generated from the output voltage, the output feedback switching unit is not affected by fluctuations in the output voltage. 15 can be controlled, and a motor drive power supply circuit that can stably control unintended stop and restart due to load fluctuation of the motor 1 can be provided.

  In addition, the time when the reference voltage charging unit 16 becomes equal to or higher than the voltage input to the non-inverting amplifier terminal takes into account the time when the motor position is not normally estimated from the induced voltage and the restart is repeated a plurality of times depending on the motor load state. In addition, a time sufficiently longer than the time from DC excitation to forced commutation set by the motor drive unit 2 is set (for example, 2 seconds), and the step-down chopper type from constant voltage control to constant current control is set. The output of the power supply unit 6 can be varied.

  In addition, the time when the reference voltage charging unit 16 becomes equal to or higher than the voltage input to the non-inverting amplification terminal is driven by a predetermined current value by constant current control after driving the motor at a low speed by constant voltage control. Therefore, the motor can be driven at a low speed for a predetermined period when the motor is started, and then the motor can be driven by constant current control. Therefore, if the motor is driven with the initial output voltage when starting the motor, noise and vibration are generated due to sudden torque generation at the moment of driving the motor, but the generated torque can be minimized by constant voltage driving. Noise and vibration at startup can be suppressed.

  As described above, the output state of the step-down chopper type power supply unit 6 is switched between constant current control and constant voltage control and power is supplied to the motor drive unit 2, which is necessary at the time of DC excitation and forced commutation at the time of starting the motor. Torque can be ensured, motor start-up failure is suppressed, and when the output voltage drops due to load fluctuation during constant current control, the motor is fluctuated by driving the motor with constant voltage control. It is possible to provide a DC sensorless brushless motor driving power supply circuit that can suppress unintentional stop and restart due to.

  In the present embodiment, the reference voltage generated by the reference voltage generation unit 11 is input via the reference voltage charging unit 16 that is charged by this reference voltage without being directly input to the input unit of the comparison unit 14. With this configuration, since the rise in the input voltage value of the reference voltage input to the comparison unit 14 can be delayed, the comparison unit 14 is set by the reference voltage charging unit 16 when the motor 1 is started. After the output voltage fixing unit 9 is operated for a predetermined period according to the time constant thus set, the output feedback unit 10 is operated by the output current detection unit, and after the start-up of the motor 1 is sufficiently stabilized, the constant voltage control is performed. Since switching to current control is possible, the motor 1 can be driven more stably.

  That is, when the reference voltage charging unit 16 is not provided, after the start-up of the motor 1 is sufficiently stabilized by delaying the rising of the reference voltage of the reference voltage generating unit 11 with respect to the rising of the step-down chopper type power supply unit 6. It is possible to switch from constant voltage control to constant current control.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  The DC sensorless brushless motor driving power supply circuit of the present embodiment includes an initial charging unit 19 in parallel with the output voltage fixing unit 9 as shown in FIG.

  The initial charging unit 19 includes a capacitor (for example, an electrolytic capacitor) connected to the output feedback unit 10 via a resistor and a third semiconductor switch 20 (for example, a diode), and the power source is a step-down chopper power source unit 6. When the step-down chopper type power supply unit 6 outputs the initial output voltage value determined by the switching frequency and inductance of the step-down chopper type power supply unit 6, the output feedback unit 10 does not depend on the operation of the output feedback switching unit 15. Is operated by the initial charging unit 19, the output state is normally fed back to the step-down chopper type power supply unit 6.

  As described above, by configuring in this way, the output of the step-down chopper type power supply unit 6 can be stabilized, and a motor drive power supply circuit that can stably supply power to the motor drive unit 2 can be provided.

(Embodiment 3)
A third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, the DC sensorless brushless motor driving power supply circuit according to the present embodiment includes a comparison discharge unit 21 that compares the output voltage of the step-down chopper type power supply unit 6 with a reference voltage.

  Here, a reference voltage is divided by a second voltage dividing resistor 22 at a non-inverting input terminal of a comparator (for example, a comparator) of the comparative discharge unit 21, and a second divided voltage equal to or lower than the maximum input terminal voltage. The generation unit 23 is connected, and the inverting input terminal has a non-inverting input terminal when the output voltage is slightly higher than the lowest operating voltage of the motor driving unit 2 (for example, 10% higher voltage). Is connected to a third divided voltage generation unit 25 that resistively divides the output voltage by the third voltage dividing resistor 24 so that it becomes the same voltage as the reference voltage divided by the resistor. The output of the comparator is A fourth semiconductor switch 26 (for example, an NPN transistor) that is connected to a reference voltage through a resistor and discharges the initial charging unit 19 and a fifth semiconductor switch 27 (for example, an NPN transistor) that discharges the reference voltage charging unit 16. ) Are connected.

  The power is applied to the step-down chopper type power supply unit 6, a predetermined initial output voltage of the step-down chopper circuit is output, and the reference voltage generated by the reference voltage generation unit 11 is the lowest operation of the comparator of the comparison discharge unit 21. When the voltage is equal to or lower than the voltage, the output of the comparative discharge unit 21 is connected to the reference voltage via a resistor, so that the fourth semiconductor switch 26 and the fifth semiconductor switch 27 become conductive, and the initial charging unit 19 and the reference voltage charging unit 16. Since the discharge continues, the output feedback unit 10 is operated by the initial charging unit 19 and the output voltage fixing unit 9, and the output feedback can be stably performed during the period until the reference voltage is stabilized. The output of the unit 6 can be stabilized. Thereafter, the initial output voltage rises, the reference voltage exceeds the minimum operating voltage of the comparator of the comparative discharge unit 21, and the comparator operates normally, and then exceeds the minimum operating voltage of the motor drive unit 2. When the motor drive unit 2 switches from DC excitation to forced commutation to synchronous operation, the resistance voltage division value of the output voltage input to the inverting input terminal becomes larger than the resistance voltage division value of the reference voltage. The comparator of the comparison discharge unit 21 outputs Low, the fourth semiconductor switch 26 and the fifth semiconductor switch 27 are turned off, the discharge of the initial charging unit 19 and the reference voltage charging unit 16 is stopped, and charging is performed. When the voltage of the reference voltage charging unit 16 starts and exceeds the threshold set in the comparison unit 14, the output feedback switching unit 15 switches from constant voltage control to constant current control.

  When the motor load is light, or when the motor drive unit 2 is locked and the motor is temporarily stopped, when the output voltage output from the step-down chopper type power supply unit 6 decreases, the reference voltage input to the non-inverting input terminal The resistance voltage dividing value of the output voltage connected to the inverting input terminal is smaller than the resistance voltage dividing value of the first and second semiconductor switches 26 and 27. Is in a conductive state, and the capacitors of the initial charging unit 19 and the reference voltage charging unit 16 are once discharged and High is output from the comparison unit 14, so that the output feedback unit 10 is output by the initial charging unit 19 or the output voltage fixing unit 9. Therefore, the output voltage is output from the step-down chopper type power supply unit 6 by constant voltage control.

  In this embodiment, two semiconductor switches are used and the initial charging unit 19 and the reference voltage charging unit 16 are discharged. However, the semiconductor switch may be used by using one element. With this configuration, the circuit configuration can be simplified.

  As described above, the comparative discharge unit 21 discharges the initial charging unit 19 and the reference voltage charging unit 16 by comparing the resistance voltage dividing value of the output voltage and the resistance voltage dividing value of the reference voltage as described above. As a result, the output of the step-down chopper power supply unit 6 can be stabilized, and power can be stably supplied to the motor drive unit 2.

(Embodiment 4)
Embodiment 4 of the present invention will be described with reference to FIG. explain. The same parts as those in the first to third embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  The DC sensorless brushless motor driving power supply circuit according to the present embodiment is configured by including a hysteresis unit 28 in the comparison unit 14 and the comparison discharge unit 21.

  When the light load state of the motor load is continued and the output voltage is controlled to a constant current by the step-down chopper type power supply unit 6 at a voltage close to the reference voltage, the output voltage falls below the reference voltage due to a slight disturbance, and the comparison unit 14 And it is calculated by the comparative discharge part 21, and the output feedback switching part 15 is operated, and it switches from constant current control to constant voltage control. After that, although the process shifts to the constant current control, the light load state of the motor load is continued, so that the constant voltage control is switched again due to a slight disturbance. Therefore, the comparison unit 14 and the comparison discharge unit 21 are each provided with a hysteresis unit 28 so that the output feedback switching unit 15 is switched. When the output state of the step-down chopper power supply unit 6 becomes a voltage close to the reference voltage, the constant current control and the constant voltage control are repeated without repeating the constant current control and the constant voltage control due to a slight disturbance. Thus, it is possible to provide a motor drive power supply circuit that suppresses the generation of noise and vibration caused by torque fluctuation caused by the difference in motor output torque.

  The power supply circuit for driving the motor according to the present invention improves the problem of motor driving caused by fluctuations in the motor load when the DC sensorless brushless motor is driven by constant current control. It is useful for ventilators equipped with DC motors for the purpose of power consumption.

DESCRIPTION OF SYMBOLS 1 Motor 2 Motor drive part 3 Motor drive power supply circuit 4 Commercial power supply 5 Rectification smoothing part 6 Step-down chopper type power supply part 7 Load current detection part 8 Output current detection part 9 Output voltage fixing part 10 Output feedback part 11 Reference voltage generation part 12 Voltage divider resistor 13 Divided voltage generation unit 14 Comparison unit 15 Output feedback switching unit 16 Reference voltage charging unit 17 First semiconductor switch 18 Second semiconductor switch 19 Initial charging unit 20 Third semiconductor switch 21 Comparative discharge unit 22 Second voltage division Resistor 23 Second divided voltage generator 24 Third divided resistor 25 Third divided voltage generator 26 Fourth semiconductor switch 27 Fifth semiconductor switch

Claims (11)

A step-down chopper type power supply unit, a motor drive unit having an inverter circuit for driving a DC sensorless brushless motor, a load current detection unit for detecting a current flowing in the motor drive unit, and a voltage corresponding to a detection value of the load current detection unit An output current detection unit for generating a value, an output voltage fixing unit for generating a voltage value set to a voltage value higher than the minimum operating voltage of the motor drive unit, and the voltage value of the output current detection unit as a first signal The voltage value is fed back to the step-down chopper type power supply unit, and an output feedback unit that feeds back the voltage value generated by the output voltage fixing unit as a second signal. The load current value flowing through the load current detection unit is A DC sensorless brushless motor drive power supply circuit that controls the output voltage of the step-down chopper type power supply unit so that the output voltage is constant. A reference voltage generation unit that generates a reference voltage having a voltage value lower than the output voltage, and the same voltage value as the reference voltage when the output voltage is higher than the lowest operating voltage of the motor drive unit As described above, the output voltage is divided by a voltage dividing resistor to generate a divided voltage generation unit, a comparison unit that compares the divided voltage and the reference voltage, and an output signal of the comparison unit that outputs the output feedback. A motor drive power supply circuit comprising an output feedback switching unit that switches the feedback signal of the unit to one of the first signal and the second signal. 2. The motor drive power supply circuit according to claim 1, further comprising an initial charging unit in parallel with the output voltage fixing unit. 3. The motor drive power supply circuit according to claim 1, wherein the reference voltage generated by the reference voltage generation unit is set to be equal to or lower than the minimum operation voltage value of the motor drive unit and equal to or higher than the minimum operation voltage of the comparison unit. A power supply circuit for driving a motor. 4. The motor drive power supply circuit according to claim 1, wherein the output feedback switching unit is constituted by using two or more semiconductor switches that operate in conflict with each other by the same input signal. Power supply circuit for driving. 5. The motor drive power supply circuit according to claim 1, further comprising a reference voltage charging unit that is charged by the reference voltage at a reference voltage input unit of a comparison unit that compares the output voltage with the reference voltage. A motor drive power supply circuit. A power supply circuit for driving a motor, characterized in that the driving voltage of the comparison section is supplied from a reference voltage. The motor drive power supply circuit according to any one of claims 1 to 6, further comprising a comparison discharge unit that compares the output voltage of the step-down chopper type power supply unit with a reference voltage, and the output voltage is lower than the reference voltage. In this case, the motor driving power supply circuit is configured to discharge the initial charging unit. 8. The motor drive power supply circuit according to claim 1, further comprising a comparison discharge unit that compares the output voltage of the step-down chopper type power supply unit with a reference voltage, and the output voltage is lower than the reference voltage. In this case, the motor driving power supply circuit is configured to discharge the reference voltage charging unit. 9. The motor drive circuit according to claim 1, wherein when the output voltage is lower than the reference voltage by the comparative discharge unit, the initial charging unit and the reference voltage charging are performed using one semiconductor element. The motor driving power supply circuit is characterized in that the part is discharged by the same comparative discharge part. 2. The motor drive power circuit according to claim 1, wherein the comparator is provided with hysteresis. The motor drive circuit according to claim 1, wherein the comparison discharge unit is provided with hysteresis.

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