JP6450939B2 - Motor drive device, compressor drive device using the same, refrigeration device, and refrigerator - Google Patents

Description

  The present invention relates to a motor drive device for driving a compressor using a brushless DC motor by inverter control, a drive device for a compressor using the same, and a refrigerator.

Conventionally, this type of motor drive device and a refrigerator using the same detect the rotational position of the rotor of the brushless DC motor, and switch the stator winding to be energized based on the rotational position. When driving a brushless DC motor in a special environment such as a compressor, the rotor position is detected by comparing 1/2 the inverter output voltage and the inverter input voltage without using a detector such as an encoder or hall element. Thus, a digital sensorless system that detects a point where the magnitude relationship changes is common. (For example, Non-Patent Document 1)
FIG. 4 shows a block diagram of the motor drive device of Non-Patent Document 1.

  In FIG. 4, an AC voltage is converted into a DC voltage by a rectifying / smoothing circuit 2 with a commercial power supply 1 as an input and input to an inverter 3. Inverter 3 has six switching elements (3a to 3f) connected by a three-phase full bridge, and diodes (3g to 3l) are connected in parallel to each switching element in the reverse direction, and the DC input is converted to three-phase AC power. The power is supplied to the brushless DC motor 4 after conversion. The position detection circuit 300 detects the relative position of the rotor from the terminal voltage of the brushless DC motor 4.

  FIG. 5 is a circuit diagram of the position detection circuit 300 of the motor drive device of Non-Patent Document 1. In FIG. 5, the position detection circuit 300 in Non-Patent Document 1 is a comparison unit 301 realized by a comparator. The terminal voltage of the brushless DC motor is input to the non-inverting input, and the inverter input voltage is used as the reference voltage at the inverting input. Is input. The position signal detects the timing at which the induced voltage appearing at the inverter output terminal of the non-conduction phase of the stator winding changes in magnitude relationship with the reference voltage (that is, the zero cross point of the induced voltage).

  FIG. 6 shows a current waveform A and a terminal voltage waveform B at the time of sensorless driving according to Non-Patent Document 1. A comparison result comparing the magnitude relationship between the terminal voltage waveform B and the reference voltage (1/2 voltage of the inverter input) is shown. The output waveform D of the position detection unit is the influence of switching by the PWM control from the waveform C, and the spike voltage X generated when the energy of the winding whose voltage supply is cut off by commutation is released as the return current. And the influence of Y are removed by waveform processing. The timing at which the signal state of the waveform D changes (rising edge or falling edge) is detected as position detection, and the brushless DC motor 4 is stably driven by repeating commutation based on this position signal. I can do it.

FIG. 7 shows a conventional motor driving device described in Patent Document 1. In FIG. As shown in FIG. 7, a brushless DC motor 4 comprising a rotor having a permanent magnet and a stator having a three-phase winding, an inverter 3 for supplying power to the three-phase winding, and a drive for driving the inverter A position detection unit 205 that detects a relative rotation position of the rotor based on an induced voltage generated in the stator winding of the brushless DC motor 4 and outputs a position signal; The first waveform generator 207 that outputs a rectangular wave or a sine wave or a waveform conforming thereto while performing duty control based on the output signal of the above, and the rectangular wave or sine wave or conforms to them to the brushless DC motor 4 A second waveform generator 209 that outputs a waveform, and an output of the first waveform generator 207 when the brushless DC motor 4 is rotating at a low speed equal to or less than a predetermined number of rotations. A switching determination unit 210 that drives the inverter 3 and drives the inverter 3 with the output of the second waveform generation unit 209 when the brushless DC motor 4 rotates at a high speed exceeding a predetermined rotation number; When driven by the waveform generator 209, a pattern for detecting the induced voltage of the brushless DC motor 4 is output at a predetermined timing, so that the brushless DC motor 4 is used as a signal of the position detector 205 at low speed. Based on this, the first waveform generating unit 207 performs high-efficiency driving by sensorless driving, and at high speed, the second waveform generating unit 209 performs synchronous fixed-frequency driving, while the position detecting unit 205 periodically induces the brushless DC motor 4. Since the rotor position information is obtained from the voltage zero cross detection and the commutation timing is determined, high load and high speed drive by synchronous drive So as to obtain the stable drive performance.

Published by Kazuo Nagatake, “Motor / Inverter Technology for Home Appliances”, published by Nikkan Kogyo Shimbun, April 28, 2000, p. 88-91

JP 2010-252406 A

  However, in the conventional configuration shown in Non-Patent Document 1 and Patent Document 1, the current that flows through the motor winding is large under conditions that require low-speed and high-torque, such as during startup in sensorless driving, and the motor winding is switched by commutation. In this case, it takes time until the energy of the winding whose power is cut off is consumed as the return current.

  In FIG. 6, consider the timing of commutation from section K2 to section K3. At the time of transition from the section K2 to the section K3, when the energization to the U-phase winding to which power is supplied is cut off, the energy accumulated in the U-phase winding is the switching element 3f and the diode 3j shown in FIG. Circulates through the brushless DC motor via the Therefore, since the diode 3j is turned on, the diode 3j is connected to the negative side of the inverter input voltage, so that a spike voltage Y is generated in the terminal voltage waveform when the return current is generated.

  Similarly, when transitioning from the section K4 to the section K1, winding energy is consumed as a return current via the switching element 3c and the diode 3g, and the diode 3g is connected to the positive side of the inverter input voltage, and a spike voltage X is generated.

  FIG. 8 is a waveform when the motor is driven with a large motor current in sensorless driving, and shows a current waveform A0 and a terminal voltage waveform B0. Since the current flowing through the brassless DC motor is high, the power supply to the U-phase winding is interrupted and the energy stored in the winding is large, and the discharge time, that is, the generation period of the spike voltages X0 and Y0 is lengthened.

  Therefore, as shown in the terminal voltage waveform B0 in FIG. 8, the spike voltages X0 and Y0 cover the zero cross point of the induced voltage, and the position signal cannot be detected.

  As a result, in the motor driving device shown in Non-Patent Document 1, since the position of the brushless DC motor cannot be accurately detected when driving with a large motor current in sensorless driving, the driving torque decreases or the torque decreases. There are problems such as a decrease in start-up performance, a decrease in motor drive efficiency, a decrease in speed stability, and an increase in vibration and noise due to speed fluctuations.

  In the configuration shown in Patent Document 1, a special pattern signal for inverter driving is output during synchronous driving, so that the position signal of the brushless DC motor can be acquired, and driving stability at high speed and high load is achieved. Although it is ensured, it cannot cope with the stability improvement in the driving state in which the motor current is large and the spike voltage covers the zero cross signal during sensorless driving. Therefore, the conventional motor driving device shown in Patent Document 1 has the same problem as that of Non-Patent Document 1 described above during sensorless driving with a high motor current.

  The present invention solves the above-mentioned conventional problems. A brushless DC motor is capable of reliably detecting a position signal of a brushless DC motor even in a driving state in which high torque driving is required at the time of starting or the like and a large motor current flows. The purpose is to improve the high torque drive performance including the start-up performance.

  In order to solve the conventional problem, a motor driving device of the present invention includes a rectifying unit that rectifies an AC voltage, and a smoothing unit that includes a capacitor that converts an output voltage of the rectifying unit into a stable DC voltage. A rectifying and smoothing unit, a brushless DC motor including a rotor having a permanent magnet and a stator having a three-phase winding, and six switching elements are connected in a three-phase bridge configuration, and the output of the rectifying unit is used as an input An inverter for supplying electric power to the three-phase winding; a position detecting means for detecting the rotational position of the rotor; a speed detecting means for detecting the speed of the brushless DC motor from a signal from the position detecting means; Energized phase determining means for determining the energized phase of the stator winding from the rotational position of the rotor and the drive speed, and drive waveform generating means for generating the drive waveform of the inverter And, when the energizing winding of the brushless DC motor is switched, as a current flows to charge the capacitor of the smoothing section from the winding to interrupt power supply, generates a drive waveform of the inverter.

  As a result, when the winding of the brushless DC motor is switched, the energy accumulated in the coil that has been de-energized returns to the power supply side as regenerative power so that the coil current that has cut off the power supply can be zeroed in a short time. Therefore, the zero-cross position of the induced voltage as position information (that is, the position signal of the brushless DC motor) can be reliably detected from the terminal of the brushless DC motor.

  The motor driving device of the present invention can improve the driving performance at a high load torque with a large current flowing through the motor at the time of starting or the like, and can improve the high torque driving performance including the starting performance of the brushless DC motor.

1 is a block diagram of a motor drive device according to Embodiment 1 of the present invention. The figure which shows the waveform of each part at the time of the motor drive in Embodiment 1 of this invention Diagram showing the path of current flow depending on the switching element Block diagram of a conventional motor drive device The figure which shows the position detection circuit of the conventional motor drive device The figure which shows the waveform of each part at the time of sensorless drive of the conventional motor drive device Block diagram of a conventional motor drive device The figure which shows the waveform of each part at the time of large current generation by the sensorless drive of the conventional motor drive device

A first aspect of the present invention is a rotor having a rectifying / smoothing unit comprising a rectifying unit for rectifying an AC voltage, a smoothing unit including a capacitor for converting the output voltage of the rectifying unit into a stable DC voltage, and a permanent magnet. And a brushless DC motor comprising a stator having a three-phase winding, an inverter for connecting six switching elements in a three-phase bridge configuration, and supplying power to the three-phase winding with the output of the rectifying unit as an input; From the position detection means for detecting the rotational position of the rotor, the speed detection means for detecting the speed of the brushless DC motor from the signal from the position detection means, the detected rotational position of the rotor, and the driving speed A current-carrying phase determining unit that determines a current-carrying phase of the stator winding; and a drive waveform generation unit that generates a drive waveform of the inverter. When it is changed, as current flows to charge the capacitor of the smoothing section from the winding to interrupt power supply to generate a drive waveform of the inverter. As a result, when the energization phase of the brushless DC motor winding is switched, the energy accumulated in the winding that is cut off from the power supply returns to the power supply side as regenerative energy. Since it can be made zero in a short time, the magnetic pole position of the motor rotor can be reliably detected from the zero cross point of the motor induced voltage appearing in the motor terminal voltage, so that the starting performance of the brushless DC motor can be improved.

  2nd invention is the drive device of the compressor driven by the motor drive device of 1st invention. As a result, when the compressor is stopped due to a power failure or the like, it is possible to restart quickly even when a large starting torque is required due to the pressure difference between the suction side and the discharge side of the compressor. The period can be shortened.

  According to a third aspect of the present invention, there is provided a condenser for condensing the high-temperature and high-pressure gas refrigerant compressed by the compressor, a decompressor for reducing the pressure of the liquid refrigerant liquefied by the condenser, and the pressure reduced by the decompressor. An evaporator for evaporating liquid refrigerant, and a refrigerant flow path blocking means for blocking a refrigerant flow path between the condenser and the evaporator, and the condenser is blocked by the refrigerant flow path blocking means when the compressor is stopped. And a refrigerant flow path between the evaporator and the compressor drive device according to the second aspect of the present invention. Accordingly, it is possible to prevent an increase in the condenser temperature due to the inflow of high-temperature refrigerant on the condenser side when the compressor is stopped. Thereby, the loss of the refrigeration cycle at the time of restarting the compressor can be reduced.

  According to a fourth invention, in the third invention, when the compressor is started from a stopped state, a pressure difference greater than or equal to a predetermined value is added between the suction side pressure and the discharge side pressure of the compressor. is there. As a result, when the compressor is restarted, it can be started from almost the same pressure state as when the compressor is being driven, so that the suction and discharge pressures of the compressor immediately become stable pressure during operation of the compressor. I can go back. Therefore, the loss of the refrigeration cycle until the stable pressure state is restored after the compressor is started can be greatly reduced.

  A fifth invention is a refrigerator using any one of the first to fourth motor driving devices, the driving device of the compressor, or the refrigeration device. As a result, even if the compressor is turned on / off to adjust the refrigerator internal temperature, the heat load is prevented from increasing due to the flow of high-temperature refrigerant in the condenser while the compressor is stopped. Since the loss of the refrigeration cycle until the pressure state at the start of the machine returns to the stable pressure at the time of compressor operation can be suppressed, a refrigerator with low power consumption can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a block diagram of a motor drive apparatus according to Embodiment 1 of the present invention.

In FIG. 1, a power source 1 is a general commercial power source. In Japan, the power source 1 is a 50 Hz or 60 Hz AC power source having an effective value of 100V. The rectifying / smoothing circuit 2 includes a rectifying unit 2a and a smoothing unit 2b, and converts the AC voltage into a DC voltage with the AC power supply 1 as an input. Although the rectifying / smoothing circuit in the first embodiment is double voltage rectification, it may be a full wave rectification configuration, a configuration that switches between full wave rectification and voltage double rectification, a power factor correction circuit (PFC), or the like.

  The inverter 3 connects six switching elements (3a to 3f) in a three-phase full bridge configuration, converts the DC input from the rectifying and smoothing circuit 2 into AC power, and supplies the brushless DC motor 4 with an arbitrary voltage and frequency. Supply AC output. A diode (3g-3l) is connected to each switching element (3a-3f) in parallel in the reverse direction. In FIG. 1, the switching element is an IGBT, but a MOSFET, bipolar transistor, SiC device, GaN device, or the like may be used.

  The position detection means 6 detects the magnetic pole position of the rotor of the brushless DC motor 4, and detects the zero cross point as a position signal from the induced voltage appearing at the terminal connected to the stator winding to which no current flows. .

  The speed detector 7 detects the driving speed of the brushless DC motor from the output signal interval of the position detector 6. The error detection means 8 detects the difference between the drive speed obtained by the speed detection means 7 and the command speed.

  The PWM control means 9 adjusts the voltage that the inverter 3 supplies to the brushless DC motor from the difference between the command speed and the actual drive speed obtained from the error detection means 8. Specifically, the switching element of the inverter 3 is turned on / off at an arbitrary frequency by PWM (pulse width modulation), and the on time (duty) per on / off cycle is adjusted. The duty is adjusted and determined by feedback control so that the actual drive speed of the brushless DC motor matches the target command speed.

  The energization phase setting means 10 sets the energization pattern and energization timing of the next energized winding based on the position signal obtained by the position detection means and the detection timing thereof, and also determines the energy of the motor winding that has cut off the voltage application by commutation. A pattern for returning to the power source side (that is, the smoothing portion) as a regeneration is added and output to the drive waveform generation means 11.

  In addition, the energization pattern to the winding set by the energization phase setting means 10 is set so that a rectangular wave of 120 degrees or more and 150 degrees or less or a waveform corresponding thereto becomes a waveform of a predetermined frequency.

  The drive waveform generation means 11 combines the energization pattern and the energization timing of the three-phase winding of the brushless DC motor by the energization phase setting means 10 with the PWM frequency set by the PWM control means 9 and the on-time so that the inverter 3 A drive waveform for turning on / off each switching element is generated and output to the drive means 12.

  The drive unit 12 turns on or off each switching element of the inverter 3 based on the drive waveform generated by the drive waveform generation unit 11.

  FIG. 2 shows waveforms at various parts during driving by the motor driving apparatus according to the first embodiment of the present invention. In FIG. 2, a waveform A1 shows a waveform of a current flowing through the motor winding, and a waveform B1 is a motor terminal voltage, both of which show a U-phase waveform. Waveforms C to H show drive waveforms of the respective switching elements of the inverter 3 by the drive means 12.

The timings indicated by “A” to “F” are commutation timings for switching energized motor windings. At this commutation timing, the drive waveform generation means 11 outputs the output set by the energization phase setting means 10 in accordance with the energization pattern of the three-phase winding of the brushless DC motor, the output waveform by the PWM control means based on feedback control, and further the winding A pattern for returning to the power supply side (electrolytic capacitor) is recovered and output to the drive circuit as energy recovered from the wire.

  A pattern for returning the winding energy at the time of commutation generated by the energized phase setting means 10 to the power source side will be specifically described with reference to FIGS. 1, 2, and 3.

  In FIG. 2, switching elements 3a and 3f are in an on state immediately before the commutation timing of “c”, and as shown in FIG. 3A, the motor current is switching element 3a → U-phase winding → W-phase winding → The power running state returns to the power supply side through the switching element 3f.

  Next, when the switching element 3a is turned off and the switching element 3b is turned by the commutation at the timing of “c”, normally, the energy stored in the U-phase winding is a diode as shown in FIG. 3j is brought into a conducting state and is recirculated and consumed in a closed circuit composed of a U-phase winding, a W-phase winding, and a switching element 3f.

  However, in the embodiment of the present invention, as shown in FIG. 3C, the W-phase lower switching element 3f is turned off for an arbitrary period simultaneously with the commutation timing. At this time, the energy stored in the U-phase winding makes the diode 3k and the diode 3i conductive, and returns to the power source (charging current of the smoothing capacitor) as regeneration.

  Thereafter, as shown in FIG. 3 (d), the switching element 3f is turned on again so that the motor current returns to the power supply state through the switching element 3b → V phase winding → W phase winding → switching element 3f. Return.

  In this manner, the pattern of returning the winding energy at the time of commutation as regeneration is to temporarily select the switching element of the phase of the coil that continues to be energized after commutation among the coils that are energized until just before commutation. Is to turn off. As described in the above commutation timing “c”, the winding that was energized until immediately before commutation, that is, the phase of the U-phase winding and W-phase winding that continues to be energized after commutation, That is, the W-phase switching element, that is, 3f is temporarily turned off.

  When the energy stored in the winding is released, the winding current becomes zero, but the time until the current becomes zero depends on the regeneration mode compared to the return mode that consumes the circuit and winding impedance. It is much shorter when charging the capacitor of the smoothing circuit.

  For this reason, in the first embodiment of the present invention in which the winding energy is released as regeneration, the current of the winding due to commutation is cut off in a short time. Therefore, even when driving with a large current by high torque driving, the induced voltage is The winding current becomes zero by the timing when the zero cross point occurs, and the zero cross can be reliably detected without being covered with the spike voltage, so that the magnetic pole position of the rotor can be accurately detected. As a result, a high torque driving performance at the time of starting or the like can be realized, and the driving performance at the time of high load including the starting performance of the brushless DC motor can be improved.

  In the description of the first embodiment of the present invention, the method of stopping energization of the switching element for a certain period as a pattern for returning the winding energy to the power source side as regeneration is described with reference to FIG. May be configured to turn on / off at a high frequency, or may be configured to turn on / off a predetermined number of pulses in synchronization with PWM switching.

(Embodiment 2)
FIG. 1 is a block diagram of a motor drive device and a refrigerator using the same according to Embodiment 2 of the present invention.

  In FIG. 1, the compression element 14 is connected to the shaft of the rotor 4a of the brushless DC motor 4, and sucks, compresses and discharges the refrigerant gas. The brushless DC motor 4 and the compression element 14 are accommodated in the same hermetic container to constitute the compressor 15. The discharge gas compressed by the compressor 15 constitutes a refrigerating and air-conditioning system that returns to the suction of the compressor 15 through the condenser 16, the decompressor 17, and the evaporator 18. Then, since endotherm is performed, cooling and heating can be performed. If necessary, a heat blower may be further promoted by using a blower or the like for the condenser 16 or the evaporator 18. In the second embodiment, the refrigeration air conditioning system is used as the refrigeration cycle of the refrigerator 19.

  In the refrigeration cycle of a refrigerator, a capillary tube is often used for the decompressor, and the inner diameter of the tube is very small. Therefore, it takes time to balance the suction and discharge pressures of the compressor when the compressor is stopped. Therefore, when the compressor is stopped due to an instantaneous power failure or the like when the compressor is driven, it is necessary to restart quickly from a state where the pressure difference between the suction and discharge of the compressor is large.

  Starting in a state where the compressor pressure is not balanced requires a large starting torque, which makes starting difficult, but by using the motor drive device of the present invention for driving the compressor, the suction and discharge pressures The compressor can be started in a stable manner with a large difference.

  Therefore, even if an instantaneous power failure occurs and the compressor stops, the compressor can be restarted quickly without having to wait until the compressor pressure balance is balanced when the power is restored. The rise in temperature can be suppressed.

  The refrigerant flow rate adjusting means 21 opens or blocks the refrigerant flow paths of the condenser 16 and the evaporator 18 in the refrigeration cycle. In the second embodiment, the refrigerant flow rate adjusting means 21 is installed between the condenser 16 and the decompressor 17, but may be installed between the decompressor 17 and the evaporator 18.

  Here, the operation of the refrigerant flow rate adjusting means 21 will be described. The refrigerant flow rate adjusting means 21 is operated in conjunction with the operation or stop of the compressor 15 so that the refrigerant flow path is opened while the compressor 15 is in operation, and the refrigerant flow path is closed when the compressor is stopped. . That is, when there is an instruction to drive the brushless DC motor 4 (that is, when the command speed is other than zero), the refrigerant flow rate adjusting means 21 is opened so that the refrigerant can circulate in the refrigeration cycle by operating the compressor for cooling the interior. When the compressor is stopped (that is, when the brushless DC motor is instructed to stop), the refrigerant flow rate adjusting means 21 is closed to block the refrigerant flow between the condenser 16 and the evaporator 18.

  In the refrigeration cycle, because the condenser is connected to the discharge (high pressure) side of the compressor and the condenser is connected to the suction (low pressure) side, there is a pressure difference between the condenser and the evaporator during compressor operation. When the compressor is stopped, the high-temperature and high-pressure gas refrigerant in the condenser 16 flows into the evaporator 18 through the decompressor 17 and is condensed and liquefied inside the evaporator 18 in order to balance the pressures of the two.

  Therefore, a high-temperature gas refrigerant flows into the evaporator installed in the refrigerator in a cooled state, and heat exchange (releases heat energy) there. Eventually, this becomes a heat load of the refrigerator, which increases the power consumption of the refrigerator.

  Therefore, in the second embodiment of the present invention, the refrigerant flow rate adjusting means 21 is closed when the compressor is stopped so that the high-temperature and high-pressure gas from the condenser side does not flow into the evaporator, so that the refrigeration using the compressor is performed. The energy efficiency of the cycle and refrigerator is improved.

Also, when starting the compressor from a state where the suction pressure of the compressor and the discharge pressure are balanced,
After startup, the pressure on the condenser side is reduced to a predetermined pressure, the pressure on the discharge side is increased to a predetermined pressure, and the refrigeration cycle is lost until it returns to a stable pressure state during compressor operation. .

  In Embodiment 2 of the present invention, the refrigerant flow rate adjusting means 21 is closed when the compressor is stopped, and the high pressure side (discharge side) and the suction side (low pressure side) of the compressor are separated. It has a pressure difference between the discharge side and the suction side equivalent to the inside. Then, the compressor is restarted with the suction pressure and the discharge pressure of the compressor being in a state equivalent to the operation state of the compressor.

  Start-up in a state where there is a pressure difference between the suction and discharge pressure of the compressor requires a very large start-up torque compared to start-up from a state in which the pressure is balanced. However, since the motor drive device of the present invention can be used to drive the compressor, a large starting torque can be generated, so even when starting with a large pressure difference between the suction side and the discharge side of the compressor. , The compressor can be started stably and smoothly. Therefore, it is possible to return to the stable pressure state during the operation of the compressor in a short time after the start-up, the loss of the refrigeration cycle at the start-up can be reduced, and the power consumption of the refrigerator can be reduced.

  The motor driving device of the present invention has improved driving performance during high torque driving or high load driving such that a large current flows through the brushless DC motor. As a result, the start-up performance of the brushless DC motor can be improved and the loss of the refrigeration cycle can be reduced. Therefore, the brushless DC motor can be applied to various uses using the brushless DC motor such as an air conditioner, a heat pump washer / dryer and a water heater.

DESCRIPTION OF SYMBOLS 2 Rectification smoothing circuit 2a Rectification part 2b Smoothing part 3 Inverter 4 Brushless DC motor 6 Position detection means 7 Speed detection means 8 Error detection means 9 PWM control means 10 Energized phase setting means 11 Drive waveform generation means 15 Compressor 16 Condenser 17 Depressurization 18 Evaporator 19 Refrigerator 21 Refrigerant flow rate adjusting means

Claims (5)

A rectifying / smoothing unit including a rectifying unit that rectifies an AC voltage, and a smoothing unit including a capacitor that converts the output voltage of the rectifying unit into a stable DC voltage, a rotor having a permanent magnet, and a three-phase winding. A brushless DC motor comprising a stator having a stator, six switching elements connected in a three-phase bridge configuration, an output for supplying power to the three-phase winding with the output of the rectifying unit as an input, and rotation of the rotor Position detecting means for detecting the position, speed detecting means for detecting the speed of the brushless DC motor from the signal from the position detecting means, the detected rotational position of the rotor, and energization of the stator winding from the driving speed An energized phase determining means for determining a phase; and a drive waveform generating means for generating a drive waveform of the inverter. When the energized winding of the brushless DC motor is switched, As current flows to charge the capacitor of the smoothing section from the windings to block the supply, the motor driving apparatus for generating driving waveforms of the inverter. A driving device for a compressor driven by the motor driving device according to claim 1. A condenser that condenses the high-temperature and high-pressure gas refrigerant compressed by the compressor; a decompressor that reduces the pressure of the liquid refrigerant liquefied by the condenser; and an evaporation that evaporates the liquid refrigerant whose pressure is reduced by the decompressor. A refrigerant flow path blocking means for blocking a refrigerant flow path between the condenser, the condenser and the evaporator, and the refrigerant flow path blocking means between the condenser and the evaporator when the compressor is stopped. A refrigerating apparatus comprising the compressor driving device according to claim 2, wherein the refrigerant flow path is blocked. The refrigeration apparatus according to claim 3, wherein when the compressor is started from a stopped state, a pressure difference greater than or equal to a predetermined value is added between a suction side pressure and a discharge side pressure of the compressor. A refrigerator having the motor drive device or compressor drive device or refrigeration device according to any one of claims 1 to 4.

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