JP6533950B2 - Motor drive device, compressor drive device using the same, refrigeration apparatus 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, and a refrigerator using the same.

Conventionally, this type of motor drive device and a refrigerator using the same detect the rotational position of the rotor of a brushless DC motor and switch the energized stator winding based on the rotational position. When driving a brushless DC motor under a special environment such as a compressor, rotor position detection does not use a detector such as an encoder or a Hall element, and compares the inverter output voltage with 1/2 of the inverter input voltage. In general, a digital sensorless method detects a point at which the magnitude relationship changes. (For example, Non Patent Literature 1)
FIG. 4 is a block diagram of the motor drive device of Non-Patent Document 1. As shown in FIG.

  In FIG. 4, an alternating voltage is converted into a direct voltage by the rectifying and smoothing circuit 2 with the commercial power source 1 as an input, and is input to the inverter 3. The inverter 3 connects six switching elements (3a to 3f) by a three-phase full bridge, and diodes (3g to 3l) are connected in parallel in the reverse direction to each switching element to make DC input into three-phase AC power It converts and supplies electric power to the brushless DC motor 4. 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 a position detection circuit 300 of the motor drive device of Non-Patent Document 1. As shown in FIG. 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 as a reference voltage is input to the inverting input. Enter 1/2 of. The position signal detects the timing at which the induced voltage appearing at the inverter output terminal of the non-energized phase of the stator windings changes in magnitude relative to 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, and the comparison result comparing the magnitude relation of the reference voltage (1/2 voltage of the inverter input) with the terminal voltage waveform B is C, and the output waveform D of the position detection unit is a spike voltage X generated from the waveform C due to the influence of switching by PWM control and energy of the winding whose voltage supply is cut off by commutation as return current. And Y are removed by waveform processing. A timing (a rising edge or a falling edge) at which the signal state of this waveform D changes is detected as position detection, and commutation based on this position signal is repeated to drive the brushless DC motor 4 stably. Can do.

FIG. 7 shows a conventional motor drive device described in Patent Document 1. As shown 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 And a position detection unit 205 for detecting a relative rotational position of the rotor based on an induced voltage generated in a stator winding of the brushless DC motor 4 and outputting a position signal, and the position detection unit 205 A first waveform generation unit 207 which outputs a rectangular wave or a sine wave or a waveform conforming to them while performing duty control based on an output signal of the first and second embodiments; and a rectangular wave or a sine wave to the brushless DC motor 4 or The second waveform generation unit 209 that outputs a waveform, and the output of the first waveform generation unit 207 when the brushless DC motor 4 is rotating at a low speed less than a predetermined rotation speed A switching determination unit 210 for driving the inverter 3 and driving the inverter 3 with the output of the second waveform generation unit 209 when the brushless DC motor 4 is rotating at a high speed exceeding a predetermined rotation speed; When driving by the waveform generation unit 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 converted to a signal of the position detection unit 205 at low speed. Based on this, the first waveform generation unit 207 performs high efficiency drive by sensorless drive, and at high speed synchronous drive of fixed frequency by the second waveform generation unit 209 while periodically inducing the brushless DC motor 4 by the position detection unit 205 Since rotor position information is obtained from voltage zero cross detection to determine commutation timing, high load and high speed drive by synchronous drive So as to obtain the stable drive performance.

Nagatake, Kazuo ed. "Motor / Inverter Technology for Home Appliances" Nikkan Kogyo Shimbun Publishing, April 28, 2000, p. 88-91

JP, 2010-252406, A

  However, in the conventional configuration described in Non-Patent Document 1 and Patent Document 1, the current flowing through the motor winding is large under the condition that low speed and high torque are required such as at the time of start at sensorless driving. When switched, it takes time for the energy of the power-cut winding to be consumed as return current.

  In FIG. 6, consider the timing of commutation from section K2 to section K3. At the time of transition from section K2 to section K3, when the energization to the U-phase winding to which power is supplied is interrupted, the energy stored in the U-phase winding is the switching element 3f and the diode 3j shown in FIG. Through the brushless DC motor and consumed. Therefore, when the diode 3j becomes conductive, it 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 section K4 to section K1, winding energy is consumed as return current through switching element 3c and diode 3g, diode 3g is connected to the positive side of the inverter input voltage, and spike voltage X is generated.

  FIG. 8 shows waveforms when driving 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 brushless 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 emission time, that is, the generation period of spike voltages X0 and Y0 becomes long.

  Therefore, as shown in the terminal voltage waveform B0 in FIG. 8, the spike voltages X2 and Y2 cover the zero cross point of the induced voltage and are in a state where the position signal can not be detected.

  As a result, in the motor drive device shown in the hit document 1, in the case of driving with a large motor current in sensorless driving, the position of the brushless DC motor can not be accurately detected. 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.

  Further, in the configuration shown in Patent Document 1, by outputting a signal of a special pattern of inverter drive during synchronous drive, the position signal of the brushless DC motor can be acquired, and the drive stability at high speed and high load can be obtained. Although secured, it can not cope with the stability improvement in the driving state where the motor current is large during sensorless driving and the spike voltage hides the zero crossing signal. Therefore, the conventional motor drive device disclosed in Patent Document 1 has the same problem as that of Non-Patent Document 1 described above at the time of sensorless driving with high motor current.

  The present invention solves the above-mentioned conventional problems, and requires high torque drive at the time of startup etc., and can reliably detect the position signal of the brushless DC motor even in the drive state where a large motor current flows. It is an object of the present invention to improve high torque drive performance including startability of the engine.

From To solve the conventional problems, the motor drive apparatus of the present invention includes a smoothing unit configured by the capacitor for converting the output voltage of the rectifying section and the rectifying section for rectifying an ac voltage to a stable DC voltage , And a brushless DC motor consisting of a rotor having a permanent magnet and a stator having a three-phase winding, and six switching elements connected in a three-phase bridge configuration, and the output of the rectification and smoothing circuit is input An inverter for supplying electric power to the three-phase winding, position detection means for detecting the rotational position of the rotor, and speed detection means for detecting the speed of the brushless DC motor from the signal from the position detection means; Energizing phase determining means for determining the electrified phase of the winding from the detected rotational position of the rotor and the driving speed, erroneously between the speed detected by the speed detecting means and the target speed And error detecting means for detecting, said as the speed of the brushless DC motor becomes the target speed, the PWM control means for adjusting the output voltage of the inverter in any PWM control of the switching elements by turning on and off the chopping of the inverter Select elements of the switching elements of the inverter that perform continuous PWM control with the elements that perform continuous conduction, so that return current generated in the three-phase winding of the brushless DC motor is returned to the rectifying and smoothing unit as regenerative energy; It has PWM phase setting means for switching, and drive waveform generation means for generating drive waveform of the inverter, and when switching the current-carrying winding of the brushless DC motor, charges the capacitor of the smoothing unit from the winding which cut off the power supply. Switching elements that perform chopping by PWM control so that Constant to is of also activating the brushless DC motor.

  As a result, when the winding of the brushless DC motor is switched, the energy stored in the winding that is de-energized is returned to the power supply side as regeneration, so that the winding current that shuts off the power supply is zeroed in a short time Therefore, it is possible to reliably detect the zero cross position of the induced voltage (that is, the position signal of the brushless DC motor) from the terminals of the brushless DC motor as the position information.

  The motor drive device of the present invention can improve the drive performance at high load torque where the current flowing through the motor at the time of start up etc. is large, and can improve the high torque drive performance including the start performance of the brushless DC motor.

Block diagram of motor drive device according to the first embodiment 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 current flow path according to the switching element state Block diagram of 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 the sensorless drive of the conventional motor drive device Block diagram of conventional motor drive device The figure which shows the waveform of each part at the time of large current generation by sensorless drive of the conventional motor drive device

The first invention includes a rectifier smoothing circuit by a capacitor for converting the output voltage of the rectifying section and the rectifying section for rectifying an ac voltage to a stable DC voltage consisting of a constructed smoothing portion, a rotor having a permanent magnet And a brushless DC motor consisting of a stator having a three-phase winding, and six switching elements connected in a three-phase bridge configuration, and an inverter supplying power to the three-phase winding using the output of the rectifying and smoothing circuit as an input A position detection means for detecting the rotational position of the rotor, a speed detection means for detecting the speed of the brushless DC motor from the signal from the position detection means, a rotational position of the rotor detected, and a drive speed Current-carrying phase determining means for determining the current-carrying phase of the winding from the fixed state, error detecting means for detecting an error between the speed detected by the speed detecting means and the target speed, and the brushless D As the speed of the motor reaches the target speed, the PWM control means for adjusting the PWM control an output voltage of the inverter by turning on and off chopping any switching elements of the inverter, the 3-phase windings of said brushless DC motor PWM phase setting means for selecting and switching an element which performs PWM control and an element performing continuous conduction among switching elements of the inverter so as to return the generated reflux current as regenerative energy to the rectifying and smoothing unit, and driving the inverter Chopping based on PWM control so that a current for charging the capacitor of the smoothing unit flows from the winding that has cut off the power supply at the time of switching of the current-carrying winding of the brushless DC motor. and selecting a switching element for, activating the brushless DC motor Than is. As a result, when the current-carrying phase of the brushless DC motor winding is switched, the energy stored in the winding whose power supply has been interrupted is returned to the power source as regenerative energy, so the current of the motor winding whose current is interrupted is shortened. Since the time can be zeroed, 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.

  A second invention is a drive device of a compressor driven by the motor drive device of the first invention. As a result, when the compressor is stopped due to a power failure or the like, the pressure difference between the suction side and the discharge side of the compressor enables rapid restart even in a state requiring a large starting torque. The period can be shortened.

  According to a third aspect of the present invention, there is provided a condenser for condensing a high temperature / high pressure gas refrigerant compressed by a compressor, a decompressor for reducing the pressure of liquid refrigerant liquefied by the condenser, and a pressure reduced by the decompressor. It has an evaporator for evaporating liquid refrigerant and refrigerant flow path blocking means for blocking the flow path of the refrigerant between the condenser and the evaporator, and the condenser flow path blocking means operates the condenser flow path while the compressor is stopped. The refrigeration apparatus according to the second aspect of the invention, further comprising: a driving device for the compressor according to the second aspect of the invention, which shuts off a refrigerant flow path between the refrigerant and the evaporator. As a result, it is possible to prevent an increase in the condenser temperature due to the inflow of the 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 the stopped state, a pressure difference between the suction side pressure and the discharge side pressure of the compressor is added by a predetermined value or more. is there. As a result, even when the compressor is restarted, it can be started from almost the same pressure condition as during driving of the compressor. Therefore, immediately after starting, the suction and discharge pressures of the compressor become stable pressure conditions during compressor operation. You can go back. Therefore, the loss of the refrigeration cycle from the start of the compressor to the return to the stable pressure state can be significantly reduced.

  A fifth invention is a refrigerator using any one of the first to fourth motor drive devices, a drive device of a compressor, or a refrigeration system. As a result, even if the on / off control of the compressor is accompanied to control the temperature inside the refrigerator, while the compressor is stopped, prevention of the increase in heat load due to the inflow of the high temperature refrigerant in the condenser into the evaporator, and compression Since the loss of the refrigeration cycle until the pressure state at the time of machine start 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. The present invention is not limited by the embodiment.

Embodiment 1
FIG. 1 is a block diagram of a motor drive device according to a first embodiment of the present invention.

  The power source 1 is a general commercial power source, and in the case of Japan, it is an AC power source of 100 Hz 50 Hz or 60 Hz. The rectifying and smoothing circuit 2 includes a rectifying unit 2a and a smoothing unit 2b, and receives the AC power supply 1 as input to convert an AC voltage into a DC voltage. Although the rectifying and smoothing circuit in the first embodiment is a voltage doubler rectification, it may be a full wave rectification configuration, a configuration in which full wave rectification and voltage doubling rectification are switched, a power factor improvement 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 an AC output. The diodes (3g to 3l) are connected in parallel in the reverse direction to the switching elements (3a to 3f). Although in FIG. 1 the switching element is an IGBT, it may be a MOSFET, a bipolar transistor, a SiC device, a GaN device or the like.

  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 where no current flows. .

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

  The PWM control means 9 adjusts the voltage supplied to the brushless DC motor by the inverter 3 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 and off at an arbitrary frequency by PWM (pulse width modulation) to adjust the on time (duty) per one on / off cycle. The duty is adjusted and determined by feedback control so that the actual driving speed of the brushless DC motor matches the target command speed.

  The energization phase setting unit 10 sets the energization pattern and the energization timing of the winding to be energized next based on the position signal obtained by the position detection unit and the detection timing, and outputs the same to the drive waveform generation unit 11 and the PWM phase setting unit 13.

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

  The PWM phase setting means 13 sets which one of the switching elements of the inverter 3 is to be on / off controlled in accordance with the PWM control, and regenerates the energy of the winding whose power supply has been cut off by commutation. The phase (switching element) to be PWM-controlled to return to the power supply (capacitor) side is selected as

  The drive waveform generation means 11 includes an energization phase pattern of the brushless DC motor set by the energization phase setting means 10, a switching frequency and an on-time per cycle according to the PWM control set by the PWM control means 9, and the PWM phase setting means 13. The drive waveform of each element of the inverter 3 is generated by combining the phases (switching elements) that perform on / off control by the set PWM control, and the drive unit 12 generates a drive waveform based on the drive waveform generated by the drive waveform generation unit 11. Each switching element of the inverter 3 is turned on or off to drive the inverter 3.

  Here, the operation of the PWM phase setting means 13 will be described using FIG. 1 and FIG.

  FIG. 2 shows the waveform of each part at the time of driving by the motor drive device according to the first embodiment of the present invention. Waveform A2 in FIG. 2 represents the U-phase winding current of the brushless DC motor. A waveform B2 is a U-phase terminal voltage of the brushless DC motor, and waveforms C2 to H2 are drive waveforms of the inverter 3 by the drive means 12. “A” to “O” in FIG. 2 indicate commutation timings for switching the energizing windings of the brushless DC motor.

  In describing the operation of the PWM phase setting means 13, the commutation timing "c" will be described. In a section between the commutation timing "i" and the commutation timing "u" (hereinafter referred to as "section iu"), the switching element 3a performs a chopping operation accompanying PWM control, 3f is in a continuously energized state, and the motor current is The current flows along a path of switching element 3a → U-phase winding → W-phase winding → switching element 3f. At the commutation timing "c", the switching element 3a is turned off and 3b is turned on. At the same time, the PWM phase setting means 13 selects the switching element 3f (that is, the W-phase low-voltage side connection element) which has been continuously energized during the section IW as a phase to be subjected to PWM chopping. Accordingly, in the section after commutation, the switching element 3b is continuously energized and the switching element 3f is subjected to chopping operation accompanied by PWM, so that the motor current is: switching element 3b → V-phase winding → W-phase winding → switching element It flows in the path of 3f.

  Next, the flow of current at commutation timing will be described using FIGS. 1, 2 and 3. FIG.

  FIG. 3 is a diagram showing a current flow path in the switching element state. In section I in FIG. 2, as shown in FIG. 3A, the switching elements 3a and 3f are in the on state, current flows in the direction of the arrow, and the brushless DC motor is in the power running state. Due to the commutation "c", 3f is subjected to chopping control accompanying PWM control at the same time when the switching element 3a is turned off. The energy of the U-phase winding is released as the switching element 3a is turned off. However, when the switching element 3f is in the on state by chopping by PWM control, the path shown in FIG. 3 (b) It is gradually released by the route, and when 3f is turned off, it returns to the capacitor on the power supply side in the regenerative mode shown in FIG. 3 (c). The discharge time of the winding energy is faster for discharge by charging to the capacitor due to regeneration than for energy consumption by the reflux mode. For this reason, in the first embodiment of the present invention, since the release of the winding energy can be released in the regenerative mode as well as the release in the reflux mode, the current of the winding due to the commutation is cut off in a short time.

  As described above, the switching element selected by the PWM phase selection means is a phase (element) that performs PWM control of the switching element of the winding phase which continues to be energized after commutation among the windings energized just before commutation. To be selected. As described in the above commutation timing "u", the winding which has been energized until just before commutation, that is, the phase of the winding which continues to be energized after commutation among the U-phase winding and W-phase winding, That is, by turning on and off the W-phase (low-voltage side) switching element, that is, 3f by PWM control, the energy stored in the winding that is de-energized by commutation is returned to the power supply side as regeneration. ing.

  By selecting the switching element by PWM control as described above, even when driving with a large current due to high torque drive at the time of start-up, etc., the winding current for which energization has been cut off quickly becomes zero. The zero crossing point can be reliably detected without being covered by the spike voltage, which enables accurate detection of the rotor pole position. As a result, the driving torque can be increased at the time of startup, and the startup performance of the brushless DC motor can be improved.

  Moreover, since it is not necessary to add the output pattern of the switching element of a special inverter in order to discharge | release the winding energy at the time of commutation, drive torque up and the improvement of starting performance can be aimed at by a very easy method. .

Second Embodiment
FIG. 1 is a block diagram of a motor drive device and a refrigerator using the motor drive device according to a second embodiment 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 housed in the same sealed container to constitute a compressor 15. The discharge gas compressed by the compressor 15 constitutes a refrigeration air conditioning system that returns to the suction of the compressor 15 through the condenser 16, the pressure reducer 17, and the evaporator 18. Since heat absorption is performed, cooling and heating can be performed. In addition, a blower etc. may be used for the condenser 16 or the evaporator 18 as needed, and heat exchange may be further promoted. Further, in the second embodiment, the refrigeration air conditioning system is used as a refrigeration cycle of the refrigerator 19.

  In the refrigeration cycle of a refrigerator, a capillary is often used as a pressure reducer, and since the inner diameter of the pipe is very small, it takes time until the suction and discharge pressures of the compressor are balanced when the compressor is stopped. Therefore, when the compressor is stopped due to a momentary power failure or the like at the time of driving the compressor, it is necessary to quickly restart the compressor from a large pressure difference between suction and discharge of the compressor.

  A large starting torque is required to start the compressor when the pressure is not balanced, which makes it difficult to start. However, by using the motor drive device of the present invention to drive the compressor, the suction and discharge pressures can be obtained. The start-up of the compressor in the state where the difference is large can also be performed stably.

  Therefore, even if a momentary power failure or the like occurs and the compressor is temporarily stopped, the compressor can be promptly restarted without waiting for activation until the pressure balance of the compressor is balanced at the time of power failure recovery. The temperature rise can be suppressed.

  The refrigerant flow rate adjusting means 21 opens or shuts off the refrigerant flow paths of the condenser 16 and the evaporator 18 of the refrigeration cycle. In the second embodiment, the refrigerant flow rate adjusting means 21 is provided between the condenser 16 and the pressure reducing device 17, but may be provided between the pressure reducing device 17 and the evaporator 18.

  Here, the operation of the refrigerant flow control means 21 will be described. The refrigerant flow rate adjusting means 21 operates in conjunction with the operation or stop of the compressor 15, and the refrigerant flow path is opened during operation of the compressor 15, and the refrigerant flow path is closed while the compressor is stopped. . That is, when there is a drive instruction for the brushless DC motor 4 (that is, the command speed is not zero), the refrigerant flow control means 21 is opened so that the refrigerant can circulate in the refrigeration cycle by the operation of the compressor for inside cooling. When the compressor is stopped (that is, the brushless DC motor is instructed to stop), the refrigerant flow control means 21 is closed to shut off the flow of the refrigerant between the condenser 16 and the evaporator 18.

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

Therefore, the high temperature gas refrigerant flows into the evaporator installed in the refrigerator in a cooled state, and heat exchange (heat energy is released) there. After all, this becomes the heat load of the refrigerator, which causes an increase in 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 to prevent the high temperature and high pressure gas from the condenser side from flowing into the evaporator, whereby refrigeration using the compressor is achieved. The cycle and the energy saving of the refrigerator have been improved.

  In addition, when the compressor is started from the state where the suction pressure of the compressor and the discharge pressure are balanced, the pressure on the condenser side is reduced to a predetermined pressure after the start, and the pressure on the discharge side is increased to a predetermined pressure Until it returns to the stable pressure state at the time of compressor operation, it will be loss of a refrigerating cycle.

  In the second embodiment 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 divided. The pressure difference between the discharge side and the suction side is equal to that of the medium. Then, the compressor is restarted with the suction pressure and the discharge pressure of the compressor being equal to the operating condition of the compressor.

  Starting with a pressure difference between the suction and discharge pressures of the compressor requires a very large starting torque as compared to starting from a pressure-balanced state. However, since a large starting torque can be generated by using the motor drive device of the present invention for driving the compressor, even in the state where a large pressure difference occurs between the suction side and the discharge side of the compressor, , You can start the compressor stably and smoothly. Therefore, it is possible to return to the stable pressure state at the time of operation of the compressor in a short time after startup, reduce loss of the refrigeration cycle at startup, and reduce the power consumption of the refrigerator.

  The motor drive device according to the present invention improves the drive performance at the time of high torque drive and high load drive where a large current flows in the brushless DC motor. As a result, since the startup performance of the brushless DC motor can be improved and the loss of the refrigeration cycle can be reduced, the invention can be applied to various applications using a brushless DC motor such as an air conditioner, a heat pump type 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 conduction phase setting means 11 drive waveform generation means 15 compressor 16 condenser 17 pressure reduction 18 Evaporator 19 Refrigerator 21 Refrigerant flow rate adjustment means

Claims (5)

A rectifying and smoothing circuit comprising a rectifying unit for rectifying alternating voltage and a smoothing unit comprising a capacitor for converting the output voltage of the rectifying unit to a stable DC voltage, a rotor having a permanent magnet, and a three-phase winding An inverter that connects a brushless DC motor consisting of a stator and six switching elements in a three-phase bridge configuration and supplies power to the three-phase winding using the output of the rectifying and smoothing circuit 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 the driving speed of the fixed winding Energizing phase determining means for determining the energizing phase, error detecting means for detecting an error between the speed detected by the speed detecting means and the target speed, and the speed of the brushless DC motor As the target speed, the PWM control means for adjusting the PWM control an output voltage of the inverter by turning on and off chopping any switching elements of the inverter, a reflux current generated in 3-phase windings of said brushless DC motor Selecting and switching among the switching elements of the inverter that perform PWM control and an element to be continuously energized among the switching elements of the inverter so as to return the regenerative energy as regenerative energy, and generating a drive waveform of the inverter A switching element having drive waveform generating means and performing chopping by PWM control so that a current for charging a capacitor of the smoothing unit flows from a winding that cuts off power supply when switching the current-carrying winding of the brushless DC motor and selecting the motor driving apparatus for starting the brushless DC motor A drive device of a compressor driven by the motor drive device according to claim 1. A condenser that condenses high-temperature and high-pressure gas refrigerant compressed by a compressor, a decompressor that reduces the pressure of liquid refrigerant liquefied by the condenser, and evaporation that evaporates the liquid refrigerant whose pressure is reduced by the decompressor Between the condenser and the evaporator by the refrigerant flow path blocking means while the compressor is stopped. The refrigerating apparatus provided with the drive device of the compressor of Claim 2 which interrupts | blocks a refrigerant | coolant flow path. The refrigeration apparatus according to claim 3, wherein when the compressor is started from a stopped state, a pressure difference between a suction side pressure and a discharge side pressure of the compressor is greater than or equal to a predetermined value. A refrigerator comprising the motor drive unit or the compressor drive unit or the refrigeration unit according to any one of claims 1 to 4.

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