JP2009254124A - Brushless dc motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a brushless DC motor in a circuit configuration requiring low cost and causing less loss. <P>SOLUTION: The brushless DC motor includes a first arm 2, a second arm 3, a third arm 4, and a fourth arm 5, each arm having diodes inversely parallel to switching elements that are connected vertically in series. The first arm 2 to the fourth arm 5 are connected in parallel respectively to a smoothing capacitor 6. A single-phase AC power supply 7 is connected to a series contact point of the diodes of the first arm 2 and to that of the diodes of the second arm 3 via a reactor 8 so that the first arm 2 and second arm 3 are driven as an AC-DC converting circuit. Either the first arm 2 or the second arm 3 is connected to one phase of a brushless DC motor 9. A series contact point of the diodes of the third arm 4 and that of the diodes of the fourth arm 5 are connected respectively to different phases of the brushless DC motor 9 to drive the third arm 4 and fourth arm 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drive control device for a brushless DC motor.

  Conventionally, this type of brushless DC motor control device has been proposed in which a power factor correction circuit is added to a rectifier circuit that converts AC power to DC (see, for example, Patent Document 1). The details will be described below.

  The brushless DC motor control device shown in Patent Document 1 will be described with reference to FIG. As shown in the figure, a converter control means 101 for controlling a power source current to a sine wave and controlling a direct current voltage to a predetermined voltage is provided, and a rectifier circuit 102 is formed by a bridge circuit of a diode 103 to provide a single-phase alternating current power source. The AC line 105 of the rectifier circuit 102 is connected to the input side connection point 106 of the rectifier circuit 102, and a booster circuit is formed by the switching element 107, the reactor 108, and the upper diode 103 of the rectifier circuit 102. It is set as the structure each provided in both. The DC power converted by the converter circuit is smoothed by the smoothing capacitor 109 and connected to the three-phase inverter circuit 110 to drive the motor 111.

  With the above configuration, when the switching element 107 is turned on, an energization circuit for the reactor 108, the switching element 107, the diode 103, and the reactor 108 is formed for the single-phase AC power supply 104. Next, when the switching element 107 is turned off, an energization circuit for the reactor 108, the diode 103, and the reactor 108 is formed for the single-phase AC power supply 104.

  Other than Patent Document 1, a drive control device combining a full-wave rectification (or half-wave rectification) circuit using a rectifier circuit and a three-phase inverter circuit is also conceivable.

Furthermore, a drive control device that combines a full bridge converter circuit for converting from AC to DC and a three-phase inverter circuit for driving a motor from DC can be considered.
JP 2002-153068 A

  In such a brushless DC motor control device, when the power factor is improved by the converter circuit, the only switching element ON / OFF control is performed in the positive half cycle of the single-phase AC power supply, so that the ripple component of the input current increases. There was a problem. In order to solve the problem, it is necessary to remove distortion of the input current by dealing with a reactor with a large inductance, a large-capacitance capacitor, or switching at a higher speed. There was a problem to do.

  Further, the converter circuit is composed of a diode full-wave rectifier circuit and two switching elements, and there is a problem that the converter circuit becomes expensive.

  Further, in the case of a simple configuration (not shown) of a rectifier circuit, a boost converter circuit, and an inverter circuit, two energization circuits pass through two diodes in the rectifier circuit and one diode in the boost converter circuit. In addition to the increase in conduction loss, the entire device becomes larger, and there is a problem that power factor improvement and harmonics are affected.

  Further, when the full bridge converter circuit and the inverter circuit are combined, the power factor of the input current can be controlled. However, a total of ten switching elements are required, so that there is a problem that the cost becomes higher.

  The present invention solves such a conventional problem, suppresses the ripple component of the input current from the single-phase AC power supply, improves the power factor, improves the conversion efficiency, and drives the motor with a cheaper configuration. An object of the present invention is to provide a brushless DC motor control device that can control the motor.

  In order to achieve the above object, the brushless DC motor control device of the present invention includes a first arm, a second arm, a third arm, and a fourth arm formed by serially connecting diodes antiparallel to the switching element in the vertical direction, The first arm to the fourth arm and the smoothing capacitor are connected in parallel to each other, and a reactor is connected between a series connection point of each diode of the first arm and the second arm from a single-phase AC power source, The first arm and the second arm are driven as an AC / DC conversion circuit, and either the first arm or the second arm is connected to one phase of the brushless DC motor, and each of the third arm and the fourth arm A series connection point of the diode is connected to a different phase of the brushless DC motor and driven.

  By this means, the first arm or the second arm can be driven as a part of an AC / DC conversion circuit for converting a single-phase AC power source to a DC and a part of an inverter circuit for driving a brushless DC motor from the DC. A DC motor control device can be provided.

  In addition, either the first arm or the second arm is configured to give priority to the control of the brushless DC motor.

  By this means, it is possible to provide a brushless DC motor control device in which the arm used in common with the AC / DC conversion circuit can be controlled so that only the modulation for one phase of the brushless DC motor is not controlled differently from the other modulations.

  Further, either one of the first arm or the second arm that operates only as an AC / DC converter circuit is configured to control to expand the other modulation range connected to one phase of the brushless DC motor. It is.

  By this means, it is possible to provide a brushless DC motor control device that can avoid limiting the modulation range of the arm for driving the brushless DC motor.

  Further, the voltage of the smoothing capacitor is configured to be boosted to a voltage higher than the voltage peak value of the single-phase AC power supply.

  By this means, the power factor control of the AC / DC converter circuit and the smoothing capacitor are not affected by the modulation of either arm used as the common arm of the AC / DC converter circuit of the first arm or the second arm and the inverter circuit. It is possible to provide a brushless DC motor control device capable of avoiding the influence on voltage control.

  Further, the voltage of the smoothing capacitor is controlled so as to be higher than 4/3 times the line voltage of the desired brushless DC motor.

  By this means, the power factor control of the AC / DC converter circuit and the smoothing capacitor are not affected by the modulation of either arm used as the common arm of the AC / DC converter circuit of the first arm or the second arm and the inverter circuit. It is possible to provide a brushless DC motor control device capable of avoiding the influence on voltage control.

  Also, the voltage of the smoothing capacitor is controlled so that one of the first arm or the second arm that operates only as an AC / DC converter circuit expands the other modulation range connected to one phase of the brushless DC motor. In this configuration, the voltage is controlled to be higher than the line voltage of the desired brushless DC motor.

  By this means, the power factor control of the AC / DC converter circuit and the smoothing capacitor are not affected by the modulation of either arm used as the common arm of the AC / DC converter circuit of the first arm or the second arm and the inverter circuit. It is possible to provide a brushless DC motor control device capable of avoiding the influence on voltage control.

  Further, the command voltage of the smoothing capacitor is changed according to the rotation speed of the brushless DC motor.

  By this means, it is possible to provide a brushless DC motor control device capable of controlling the modulation of the inverter circuit to the smoothing capacitor voltage optimum for the rotational speed regardless of the low speed and high speed operation of the brushless DC motor.

  Further, the command voltage of the smoothing capacitor is configured to change according to the rotation angle of the brushless DC motor.

  By this means, it is possible to provide a brushless DC motor control device capable of setting the voltage of the smoothing capacitor to the minimum necessary voltage.

  Further, either the first arm or the second arm, the third arm, and the fourth arm are configured to modulate so as to suppress a change in rotational speed at a specific rotational position of the rotor of the brushless DC motor. It is.

  By this means, it is possible to provide a brushless DC motor control device capable of keeping the rotation speed of the brushless DC motor constant even when the load varies according to the rotation angle.

  In addition, either the first arm or the second arm, the third arm, and the fourth arm are configured to use a switching element configured in the same package.

  By this means, it is possible to provide a brushless DC motor control device that can reduce variations in the saturation voltage and switching speed of the switching elements.

  According to the present invention, a first arm, a second arm, a third arm, a fourth arm, and a smoothing capacitor that are formed by connecting diodes antiparallel to the switching element in the vertical direction, the first arm to the fourth arm, and the smoothing capacitor. Are connected in parallel to each other, and a reactor is connected between a single-phase AC power source and a series connection point of each diode of the first arm and the second arm, and the first arm and the second arm are connected to an AC / DC converter circuit. Either the first arm or the second arm is connected to one phase of the brushless DC motor, and the series connection point of the diodes of the third arm and the fourth arm is connected to the phase of the brushless DC motor. By connecting to a different phase and driving, the first arm or the second arm is a part of an AC / DC converter circuit that converts a single-phase AC power source to DC and a DC As a part of the inverter circuit that drives the brushless DC motor, the input current from the single-phase AC power source can be a sine wave, and the power factor can be improved and the harmonic content can be reduced. In an AC / DC converter circuit using a normal rectifier circuit, loss can be reduced by passing a switching element from a loss generated by a diode, and the AC / DC converter circuit does not need to have a full bridge configuration, ie, switching for one arm. It is possible to provide a brushless DC motor control device that can reduce the number of elements and can be realized at low cost.

  In addition, either the first arm or the second arm is configured to give priority to the control of the brushless DC motor, and the arm used in common with the AC / DC converter circuit is equivalent to one phase of the brushless DC motor. Therefore, it is possible to provide a brushless DC motor control device that can prevent the noise and vibration of the brushless DC motor from being generated.

  Furthermore, either one of the first arm or the second arm that operates only as an AC / DC converter circuit is configured to be controlled so as to expand the other modulation range connected to one phase of the brushless DC motor. Thus, it is possible to provide a brushless DC motor control device that is effective in avoiding limiting the modulation range of the arm for driving the brushless DC motor and avoiding the limitation of the rotation speed range of the brushless DC motor.

  Also, the voltage of the smoothing capacitor is boosted to a voltage higher than the voltage peak value of the single-phase AC power supply, so that the AC arm of the first arm or the second arm and the common arm of the inverter circuit Regardless of the modulation of one of the arms used, the influence on the power factor control of the AC / DC converter circuit and the control of the smoothing capacitor voltage can be avoided, and the limitation on the rotation speed range of the brushless DC motor can be avoided. It is possible to provide a brushless DC motor control device that has the effect of being able to.

  Further, the voltage of the smoothing capacitor is controlled so as to be higher than 4/3 times the line voltage of the desired brushless DC motor. It is not affected by the modulation of either arm used as the common arm of the AC / DC converter circuit and the inverter circuit, avoids the influence on the power factor control of the AC / DC converter circuit and the voltage control of the smoothing capacitor, and single phase It is possible to provide a brushless DC motor control device having an effect of avoiding adverse effects on the AC power supply.

  Also, the voltage of the smoothing capacitor is controlled so that one of the first arm or the second arm that operates only as an AC / DC converter circuit expands the other modulation range connected to one phase of the brushless DC motor. And, it was used as a common arm of the AC / DC converter circuit of the first arm or the second arm and the inverter circuit by controlling the voltage to be higher than the line voltage of the desired brushless DC motor. The effect that the influence on the power factor control of the AC / DC converter circuit and the control of the voltage of the smoothing capacitor can be avoided and the adverse effect on the single-phase AC power supply can be avoided regardless of the modulation of one of the arms. It is possible to provide a brushless DC motor control device having

  Further, the command voltage of the smoothing capacitor is changed according to the rotation speed of the brushless DC motor, so that the modulation of the inverter circuit can be complicated regardless of whether the brushless DC motor operates at low speed or high speed. In addition, it is possible to provide a brushless DC motor control device having an effect of reducing the loss of the AC / DC conversion circuit and the inverter circuit because the voltage of the smoothing capacitor is not more than necessary. .

  Further, the command voltage of the smoothing capacitor can be changed according to the rotation angle of the brushless DC motor, so that the voltage of the smoothing capacitor can be set to the minimum necessary voltage. In addition, it is possible to provide a brushless DC motor control device having an effect that the loss of the inverter circuit can be reduced.

  Further, either the first arm or the second arm, the third arm, and the fourth arm are configured to modulate so as to suppress the rotational speed change at the specific rotational position of the rotor of the brushless DC motor. Thus, even when the load fluctuates according to the rotation angle, the brushless DC motor is effective in that the rotation speed of the brushless DC motor can be kept constant and noise and vibration of the entire apparatus can be reduced. A control device can be provided.

  In addition, either the first arm or the second arm, the third arm, and the fourth arm are configured to use a switching element configured in the same package, so that the saturation voltage of the switching element or The variation in switching speed can be reduced, and the influence on the input from the single-phase AC power source, such as power factor and harmonics, can be minimized without correcting the modulation rate of each phase. In addition, since the line voltage can be equalized with respect to the output to the brushless DC motor, it is possible to provide a brushless DC motor control device that has the effect of reducing the overall apparatus noise and vibration.

  According to the first aspect of the present invention, there are provided a first arm, a second arm, a third arm, a fourth arm, and a first arm to a fourth arm, each of which is formed by vertically connecting diodes antiparallel to the switching element. An arm and a smoothing capacitor are connected in parallel to each other, a reactor is connected between a single-phase AC power source and a series connection point of each diode of the first arm and the second arm, and the first arm and the second arm Is driven as an AC / DC converter circuit, and either the first arm or the second arm is connected to one phase of a brushless DC motor, and the series connection point of each diode of the third arm and the fourth arm is The brushless DC motor is configured to be connected to different phases and driven, and the first arm or the second arm is an AC / DC conversion circuit that converts a single-phase AC power source to DC. Can be driven as a part of the inverter circuit and part of the inverter circuit that drives the brushless DC motor from the direct current, and the input current from the single-phase AC power supply can be made a sine wave, thereby improving the power factor and reducing the harmonic content. In addition, in an AC / DC converter circuit using a normal rectifier circuit, loss can be reduced by passing a switching element from loss generation by a diode, and there is no need for the AC / DC converter circuit to have a full bridge configuration. One arm, that is, two switching elements can be reduced, which has the effect that it can be realized at low cost.

  In addition, either the first arm or the second arm is configured to give priority to the control of the brushless DC motor, and the arm used in common with the AC / DC conversion circuit is one phase of the brushless DC motor. Only the minute modulation can be prevented from being different from the other modulations, and the noise and vibration of the brushless DC motor can be prevented.

  Further, either one of the first arm or the second arm that operates only as an AC / DC converter circuit is configured to control to expand the other modulation range connected to one phase of the brushless DC motor. Thus, it is possible to avoid limiting the modulation range of the arm for driving the brushless DC motor, and to avoid limiting the rotation speed range of the brushless DC motor.

  Further, the voltage of the smoothing capacitor is boosted to a voltage higher than the voltage peak value of the single-phase AC power supply, and the AC / DC conversion circuit of the first arm or the second arm and the common arm of the inverter circuit Regardless of the modulation of either one of the arms used as an influence, the influence on the power factor control of the AC / DC converter circuit and the control of the voltage of the smoothing capacitor is avoided, and the limitation on the rotational speed range of the brushless DC motor is avoided. It has the effect of being able to.

  Further, the voltage of the smoothing capacitor is controlled so as to be higher than four-thirds the line voltage of the desired brushless DC motor, and the first arm or the second arm The AC / DC converter circuit and inverter circuit used as a common arm are not affected by the modulation of either arm, avoiding the influence on the power factor control of the AC / DC converter circuit and the voltage control of the smoothing capacitor. An adverse effect on the phase AC power supply can be avoided.

  Also, the voltage of the smoothing capacitor is controlled so that one of the first arm or the second arm that operates only as an AC / DC converter circuit expands the other modulation range connected to one phase of the brushless DC motor. In addition, the control is made so that the voltage is higher than the line voltage of the desired brushless DC motor, and is used as a common arm for the AC / DC conversion circuit of the first arm or the second arm and the inverter circuit. The effect on the power factor control of the AC / DC converter circuit and the control of the voltage of the smoothing capacitor can be avoided and the adverse effect on the single-phase AC power supply can be avoided regardless of the modulation of one of the arms. Has an effect.

  Furthermore, the command voltage of the smoothing capacitor is configured to change according to the number of rotations of the brushless DC motor, and the modulation of the inverter circuit is complexly controlled regardless of whether the brushless DC motor operates at low speed or high speed. There is no need to construct a system, and since the voltage of the smoothing capacitor is not more than necessary, a brushless DC motor control device that can reduce the loss of the AC / DC conversion circuit and the inverter circuit is provided. it can.

  Further, the command voltage of the smoothing capacitor can be changed according to the rotation angle of the brushless DC motor, so that the voltage of the smoothing capacitor can be set to the minimum necessary voltage. And the loss of the inverter circuit can be reduced.

  Further, either the first arm or the second arm, the third arm, and the fourth arm are configured to modulate so as to suppress a change in rotational speed at a specific rotational position of the rotor of the brushless DC motor. Even when the load fluctuates according to the rotation angle, the rotation speed of the brushless DC motor can be kept constant, and noise and vibration of the entire apparatus can be reduced.

  In addition, either the first arm or the second arm, the third arm, and the fourth arm are configured to use a switching element configured in the same package, and the saturation voltage of the switching element And variation in switching speed can be reduced, and the influence on the input from the single-phase AC power supply, such as power factor and harmonics, should be minimized without correcting the modulation rate of each phase. In addition, since the line voltage can be equalized with respect to the output to the brushless DC motor, the entire apparatus can be reduced in noise and vibration.

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

(Embodiment 1)
FIG. 1 is a configuration diagram of a brushless DC motor control device according to Embodiment 1 of the present invention.

  In the figure, a brushless DC motor control device 1 includes a first arm 2, a second arm 3, a third arm 4, a fourth arm 5, and a first arm formed by serially connecting diodes antiparallel to switching elements in the vertical direction. 2 to the fourth arm 5 and the smoothing capacitor 6 are connected in parallel to each other, and a reactor 8 is connected between the single-phase AC power supply 7 and the series connection point of the diodes of the first arm 2 and the second arm 3, respectively. The first arm 2 and the second arm 3 are driven as an AC / DC conversion circuit, and either the first arm 2 or the second arm 3 is connected to one phase of the brushless DC motor 9, The series connection points of the diodes of the arm 4 and the fourth arm 5 are connected to different phases of the brushless DC motor 9, and the first arm 2, the second arm 3, the third arm 4, and the fourth arm 5 are driven and controlled. Is equipped with a control means 10. The control means 10 includes a microcomputer 10a (not shown) and a gate drive circuit 10b (not shown). Here, the second arm 3, the third arm 4, and the fourth arm 5 employ a module 11 configured in the same package in order to reduce variation in characteristics of each switching element.

  Next, a modulation method of the first arm 2 provided in the control means 10 will be described with reference to FIG. Since the second arm 3, the third arm 4, and the fourth arm 5 are the same as normal three-phase PWM control (sinusoidal wave energization), detailed description is omitted. The second arm 3 that functions as an AC / DC converter circuit performs control giving priority to three-phase PWM control. In the first arm 2, the modulation rate is determined by giving priority to the driving of the brushless DC motor 9 by the second arm 3, which is the other side of the AC / DC conversion circuit (a sine wave voltage is applied between the windings of the brushless DC motor 9). Therefore, as the arm dedicated to the AC / DC converter circuit, the first arm 2 is configured so that the current flowing through the reactor 8 with the line voltage to the second arm 3 has a power factor of 1. While controlling, proportional-integral control is performed with the voltage of the smoothing capacitor 6 being higher than four-thirds the line voltage of the brushless DC motor 9 as a target voltage.

  FIG. 3 shows control for setting the voltage of the smoothing capacitor 6 to a voltage higher than four-thirds the line voltage of the brushless DC motor 9. The figure shows each phase voltage of the brushless DC motor 9 and each line voltage of the brushless DC motor 9 when the negative side of the smoothing capacitor 6 is 0V. As shown in the figure, the peak value of the line voltage corresponds to three-quarters of the voltage between the positive peak and the negative peak of the three-phase voltage applied to the brushless DC motor 9. Therefore, the voltage of the smoothing capacitor 6 takes into account the voltage drop due to the ON resistance of the switching elements of the second arm 3 to the fourth arm 5 and the voltage drop due to the diode in addition to the voltage more than four-thirds of the line voltage. The desired line voltage can be applied to the brushless DC motor 9 by using the above-described voltage.

  Next, FIG. 4 shows a control block for determining the modulation rate of the first arm 2 provided in the control means 10. As shown in the figure, the modulation factor of the first arm 2 is calculated by calculating the deviation between the target value (Vdc target value) of the voltage (Vdc) of the smoothing capacitor 6 and the detected value (Vdc (t)), and performing proportional integral control. Input to the instrument. The output current command value calculates an instantaneous target value (current instantaneous command value determined by the phase angle) via a limiter circuit. The deviation between the calculated instantaneous target value and the detected current value (current instantaneous value, Iac (t)) is calculated and input to the proportional integration controller. The modulation factor output from the proportional-integral controller is compared with a triangular wave and becomes a drive signal for the gate driver circuit.

  5 shows the phase current waveforms (Ia, Ib, Ic) of the brushless DC motor 9 when controlled by the above-described modulation factor determination method, the input current waveform (Iac) from the single-phase AC power supply 7, and the brushless DC. A voltage waveform (Vuv, Vvw, Vwu) between the windings of the motor 9, a voltage waveform (Vdc) across the smoothing capacitor 6, and an AC power supply voltage waveform (Vac) are shown. As shown by the phase current waveforms (Ia, Ib, Ic) in the figure, the phase current is a sinusoidal current, and as shown by the input current waveform (Iac), the input current from the single-phase AC power supply 7 is almost equal. It has a sinusoidal current.

  As described above, in the first embodiment, the brushless DC motor control device 1 is configured such that the first arm 2 or the second arm 3 includes a part of the AC / DC conversion circuit that converts the single-phase AC power supply 7 to DC and DC. Can be driven as a part of an inverter circuit for driving the brushless DC motor 9, and the input current from the single-phase AC power source 7 can be a sine wave, which can improve the power factor and reduce the harmonic content. At the same time, in an AC / DC converter circuit using a normal rectifier circuit, loss can be reduced by passing a switching element from the occurrence of a loss due to a diode, and the AC / DC converter circuit does not need to have a full-bridge configuration, and is equivalent to one arm. That is, two switching elements can be reduced, which can be realized at low cost. Further, the arm used in common with the AC / DC converter circuit can prevent only the modulation for one phase of the brushless DC motor 9 from being controlled differently from the other modulations, and noise and vibration of the brushless DC motor 9 are generated. Can be prevented. Further, the voltage of the smoothing capacitor 6 is higher than the voltage peak value of the single-phase AC power supply 7 (in this embodiment, higher than the voltage obtained by adding four thirds of the line voltage of the brushless DC motor 9). Therefore, one of the arms used as a common arm of the AC / DC conversion circuit of the first arm or the second arm and the inverter circuit is boosted to 1.5 times the peak voltage of the single-phase AC power source 7). Therefore, the influence on the power factor control of the AC / DC conversion circuit and the voltage control of the smoothing capacitor 6 can be avoided, and the limitation on the rotation speed range of the brushless DC motor 9 can be avoided. In addition, either the first arm 2 or the second arm 3 and the third arm 4 and the fourth arm 5 use switching elements configured in the same package, and the saturation voltage and switching of the switching elements are used. The variation in speed can be reduced, and the influence on the input from the single-phase AC power source 7, for example, the influence on the power factor and harmonics can be minimized without correcting the modulation rate of each phase. In addition, since the line voltage can be equalized with respect to the output to the brushless DC motor 9, the entire apparatus can be reduced in noise and vibration.

  In the first embodiment, the switching element is illustrated as a MOSFET, but there is no difference in operation and effect even if the switching element is an IGBT element or a SiC element.

(Embodiment 2)
Hereinafter, the configuration of the second embodiment of the present invention will be described with reference to FIG. Note that the same components as those in Embodiment 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in the figure, the voltage of the smoothing capacitor 6 is such that the first arm 2 operating only as an AC / DC converter circuit expands the modulation range of the second arm 3 connected to one phase of the brushless DC motor 9. In addition to the control, the voltage is increased to a voltage higher than the desired line voltage of the brushless DC motor 9. In the control block diagram shown in the figure, the voltage value (Vdc (t)) of the smoothing capacitor 6 is calculated after calculating the deviation from the line voltage (Vmotor) of the brushless DC motor 9 and inputting it to the proportional-integral controller. , Input to the limiter, calculate the instantaneous current command value from the single-phase AC power supply 7, compare with the actual instantaneous current value (Iac (t)), and input the deviation to the proportional integral controller to modulate The rate is calculated. FIG. 7 shows the control for setting the voltage of the smoothing capacitor 6 to the line voltage of the brushless DC motor 9. FIG. 7 shows each phase voltage of the brushless DC motor 9 and each line voltage of the brushless DC motor 9 when the negative side of the smoothing capacitor 6 is set to 0V. As shown in the figure, the voltage of the smoothing capacitor 6 and the voltage (Vu, Vv, Vw) between each phase of the brushless DC motor 9 and the negative side of the smoothing capacitor 6 are not modulated on a sine wave, but brushless. The three-phase line voltage applied to the DC motor 9 is controlled to be a sine wave. Since the control target voltage is the voltage (Vu, Vv, Vw) of each phase in the figure, it can be obtained by on / off control of the upper and lower switching elements of the second arm 3 to the fourth arm 5. The control of the first arm 2 at this time is performed by performing proportional-integral control from the U-phase target voltage Vu, the detection voltage of the single-phase AC power supply 7, the inductance of the reactor 8, and the current flowing through the reactor 8, The modulation factor is calculated to control the power factor of the input current.

  As described above, in the second embodiment, it is not necessary to set the voltage of the smoothing capacitor 6 to an unnecessarily high voltage, and the first arm 2 that operates only as an AC / DC conversion circuit is used as one phase of the brushless DC motor 9. Can be controlled so as to expand the modulation range of the second arm 3 connected to the inverter, and is not affected by the modulation of the second arm 3 used as a common arm of the AC / DC converter circuit and the inverter circuit, and the AC / DC converter The adverse effect on the single-phase AC power supply 7 can be avoided while avoiding the influence on the power factor control of the circuit and the voltage control of the smoothing capacitor 6.

(Embodiment 3)
Hereinafter, the configuration of the third embodiment of the present invention will be described with reference to FIG. Note that the same components as those in the first or second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in the figure, the command voltage of the smoothing capacitor 6 is configured to change according to the rotation speed and rotation angle of the brushless DC motor 9. The voltage (Vdc (t)) of the smoothing capacitor 6 is controlled so that the first arm 2 operating only as an AC / DC converter circuit expands the modulation range of the second arm 3 connected to one phase of the brushless DC motor 9. In addition, a correction voltage V2 obtained by multiplying a desired line-to-line voltage (Vmotor) of the brushless DC motor 9 by sin θ derived from the phase angle of the brushless DC motor 9 is calculated. Further, the number of revolutions is detected from the voltage (Vmotor (t)) of the brushless DC motor 9, and the number of revolutions is divided by the corrected maximum number of revolutions of the brushless DC motor 9 (for example, the rated number of revolutions). Of the brushless DC motor 9 is multiplied by the line voltage (Vmotor). The multiplied voltage value is input to the limiter, and the correction voltage V1 is calculated by limiting the line voltage (Vmotor) of the desired brushless DC motor 9. Thereafter, the calculated correction voltages V1 and V2 are compared, and the boosting operation is performed so that the higher correction voltage becomes the final target voltage of the smoothing capacitor 6.

  As described above, in the third embodiment, the brushless DC motor control device 1 changes the target value (Vdc target value) of the smoothing capacitor 6 according to the rotation speed and rotation phase of the brushless DC motor 9, There is no need to construct a complicated control system for modulating the inverter circuit regardless of whether the brushless DC motor 9 is operated at low speed or high speed, and the voltage of the smoothing capacitor 6 is not increased more than necessary. The loss for the inverter circuit can be reduced. Further, the command voltage of the smoothing capacitor 6 can make the voltage of the smoothing capacitor 6 the minimum necessary voltage, and the loss of the AC / DC conversion circuit and the inverter circuit can be reduced.

(Embodiment 4)
Hereinafter, the configuration of the fourth embodiment of the present invention will be described with reference to FIG.

  The same components as those in the first to third embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in the figure, the brushless DC motor 9 is connected to a non-uniform load (for example, a rotor of a compressor) with respect to the rotating shaft.

  Next, a modulation method for suppressing a change in rotational speed at a specific rotational position, that is, a specific rotational angle of the rotor of the brushless DC motor 9 when an asymmetric load is connected will be described with reference to FIG. As shown in the figure, the modulation factor calculation of the second arm 3 on the brushless DC motor 9 side first calculates an instantaneous current value in each phase obtained by multiplying a target current value (Imotor (t)) by sin θ. Further, after detecting the phase ω from the line voltage (Vmotor (t)), the angular velocity is calculated, and the proportional integral term of the target value (target dωt (ω)) and the proportional integral term of the angular velocity change amount in each phase are added. The modulation factor (m_ref) of the second arm 3 is calculated by adding the current correction value obtained by finally adding the corrected terms. Gate drive is performed by comparing the calculated modulation factor with a triangular wave. Further, the modulation method of the third arm 4 and the fourth arm 5 is driven with a modulation rate in which the second arm 3 is shifted in phase by 120 degrees and 240 degrees.

  Next, a modulation method of the first arm 2 that controls the voltage of the smoothing capacitor 6 to a command voltage according to the modulation method of the brushless DC motor 9 will be described with reference to FIG. In the figure, the modulation method of the first arm 2 will be described. As shown in the figure, the modulation factor of the first arm 2 is calculated by inputting the deviation between the actual voltage value (Vdc (t)) of the smoothing capacitor 6 and the target voltage value (Vdc_ref) to the proportional integration controller. The instantaneous target current value (Iac_ref) is calculated by multiplying the output by sin θ of the single-phase AC power supply 7 (sin (Vac (t)) in the figure. The calculated instantaneous target current value (Iac_ref) and the actual current value ( Iac (t)) is input to the proportional integral controller, and a correction voltage target value between the lines of the first arm 2 and the second arm 3 for flowing through the reactor 8 is calculated. The correction voltage target value is added to the product of the voltage (Vac (t)) of the single-phase AC power supply 7 and the modulation factor (m_ref) of the second arm 3, and the deviation from the second arm 3 is actually applied to the smoothing capacitor 6. Dividing by the voltage value (Vdc (t)) Calculating a modulation factor of the first arm 2.

  As described above, in Embodiment 4, unless special phase control is conventionally performed, if the load is not uniform with respect to the rotating shaft, the torque is insufficient when the rotating shaft angle becomes a specific angle. However, the torque is excessive and the motor is accelerated more than necessary, or the input current from the single-phase AC power source 7 is distorted. 6 is changed in accordance with the rotational speed of the brushless DC motor 9, so that it is not necessary to construct a complicated control system for modulating the inverter circuit regardless of whether the brushless DC motor 9 is operated at low speed or high speed. Since the voltage is changed according to the rotation angle of the brushless DC motor 9, the voltage of the smoothing capacitor 6 is not increased more than necessary, and the AC / DC conversion circuit and the inverter And thus it can reduce the loss of road component. Further, the command voltage of the smoothing capacitor 6 has an effect that the voltage of the smoothing capacitor 6 can be set to the minimum necessary voltage, and the loss corresponding to the AC / DC conversion circuit and the inverter circuit can be reduced. . Further, since either the first arm 2 or the second arm 3 and the third arm 4 and the fourth arm 5 are modulated so as to suppress a change in rotational speed at a specific rotational angle of the brushless DC motor 9. Even when the load applied to the brushless DC motor 9 fluctuates according to the rotation angle, the rotation speed of the brushless DC motor 9 can be kept constant, and noise and vibration of the entire apparatus can be reduced. Become.

  The brushless DC motor control device of the present invention can be realized by various devices using the brushless DC motor at low power consumption and at low cost. In addition to controlling fan motors for home air conditioning equipment, It can also be applied to load control where required torque varies depending on the rotation angle of a simple rotor, or for business use.

Configuration diagram of brushless DC motor control device according to Embodiment 1 of the present invention Explanatory drawing about the modulation method of the first arm 2 Explanatory diagram regarding voltage control of the smoothing capacitor 6 Control block diagram for determining the modulation factor of the first arm 2 Current / voltage waveform diagram with the same modulation factor Control block diagram of brushless DC motor modulation factor determination in Embodiment 2 of the present invention Explanatory diagram regarding voltage control of the smoothing capacitor 6 Control block diagram of brushless DC motor modulation factor determination in Embodiment 3 of the present invention Configuration diagram of brushless DC motor control apparatus according to Embodiment 4 of the present invention Control block diagram of modulation method for suppressing change in rotation speed at the same specific rotation angle Control block diagram of modulation method of the first arm 2 Configuration diagram of conventional brushless DC motor control device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless DC motor control apparatus 2 1st arm 3 2nd arm 4 3rd arm 5 4th arm 6 Smoothing capacitor 7 Single phase alternating current power supply 8 Reactor 9 Brushless DC motor 10 Control means 11 Module

Claims (10)

A first arm, a second arm, a third arm, and a fourth arm formed by connecting diodes in reverse parallel with the switching element in series up and down, and the first to fourth arms and the smoothing capacitor are connected in parallel to each other. , A reactor is connected between a single-phase AC power source and a series connection point of the diodes of the first arm and the second arm, and the first arm and the second arm are driven as an AC / DC conversion circuit, and Either the first arm or the second arm is connected to one phase of the brushless DC motor, and the series connection points of the diodes of the third arm and the fourth arm are connected to different phases of the brushless DC motor. A brushless DC motor control device characterized by being driven. 2. The brushless DC motor control device according to claim 1, wherein either the first arm or the second arm gives priority to the control of the brushless DC motor. 2. One of the first arm and the second arm that operates only as an AC / DC converter circuit is controlled to expand the other modulation range connected to one phase of the brushless DC motor. The brushless DC motor control device described. 2. The brushless DC motor control device according to claim 1, wherein the voltage of the smoothing capacitor is boosted to a voltage higher than the voltage peak value of the single-phase AC power supply. 2. The brushless DC motor control device according to claim 1, wherein the voltage of the smoothing capacitor is controlled to be higher than four times the line voltage of a desired brushless DC motor. 4. The brushless DC motor control device according to claim 3, wherein the voltage of the smoothing capacitor is controlled to be higher than a desired line voltage of the brushless DC motor. 2. The brushless DC motor control device according to claim 1, wherein the command voltage of the smoothing capacitor is changed in accordance with the rotational speed of the brushless DC motor. 2. The brushless DC motor control device according to claim 1, wherein the command voltage of the smoothing capacitor is changed according to a rotation angle of the brushless DC motor. 2. The first arm or the second arm, and the third arm and the fourth arm are modulated so as to suppress a change in rotational speed at a specific rotational position of the rotor of the brushless DC motor. The brushless DC motor control device described. 2. The brushless DC motor control device according to claim 1, wherein any one of the first arm and the second arm, the third arm, and the fourth arm use switching elements configured in the same package.

Images