JP2022173520A - Open winding motor driving device and refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an open winding motor driving device that can suppress occurrence of a zero-axis current.

SOLUTION: In an embodiment of the present invention, six output terminals of an open-winding-structured motor are connected to the output terminals of primary and secondary side inverters. A control unit controls an electric current for energizing a motor and a rotational speed based on each line-to-line duty ratio of the primary and secondary side inverters in PWM control, and has a zero-axis current suppression unit for suppressing a zero-axis current flowing in the same direction of three phases between the primary and secondary side inverters. The zero-axis current suppression unit performs: generating each zero-axis voltage between the output of a first switching pattern for generating a voltage to be applied to the motor without generating the zero-axis voltage acting equally on three phases of the motor and the output of the first switching pattern again, and between the output of the first switching pattern and the output of a second switching pattern for not generating a voltage acting on the phases of the motor, nor generating the zero-axis voltage; and inserting a third switching pattern for generating a voltage acting on the phases of the motor.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD Embodiments of the present invention relate to a device for driving a motor having an open winding structure and a refrigeration cycle apparatus including the device.

For example, when driving an AC motor such as a permanent magnet synchronous motor, it is necessary to convert a DC power supply into three-phase AC power using an inverter. However, as the capacity of the motor increases, the current flowing through the inverter also increases, causing problems such as heat generation in the power devices forming the inverter.

To address this problem, in Non-Patent Document 1, Patent Document 1, etc., the windings of a three-phase motor are not star-connected, but in an open state, and are driven by connecting inverters to both ends of the three-phase windings. A system is proposed. According to this system, by using two inverters, the voltage that can be applied to both ends of the three-phase windings can be doubled, so that the motor can be driven at a higher speed. Alternatively, by increasing the number of winding turns, it is possible to drive a motor that outputs high torque with a small current.

Drive systems for open-winding motors often take three forms shown in FIGS. 13 to 15 depending on their circuit configurations. Although the configuration shown in FIG. 13 requires two DC power sources that are insulated from each other, the DC voltage of the inverter can be doubled, and in principle the zero-axis current that flows commonly through the three-phase windings does not flow. There is an advantage. In the configuration shown in FIG. 14, two inverters share the DC link voltage. Although this configuration requires only one power supply, there is a problem that the zero-axis current flows through the DC portions of the mutual inverters. In the configuration shown in FIG. 15, the power supply for one of the inverters is composed of a capacitor, so one power supply is also sufficient. However, reactive power control is required to charge the capacitor.

May 2002, The Institute of Electrical Engineers of Japan D Section Transactions Vol. 122, No.5, p430-438, "High Efficiency Low Noise Motor Drive System Using Open Winding AC Motor and Two Space Voltage Vector Modulation Inverters", Yoshihisa Kawabata, Motoshi Nasu, Takao Kawabata

International Publication No. WO2016/125557 pamphlet

Of the three conventional configurations, the one that can be realized at the lowest cost is the configuration shown in FIG. 14, which does not require an increase in the number of parts or a power supply. There's a problem. The zero-axis current does not have a path in a general star-connected motor, but in a configuration that shares the DC link voltage, it flows in the three phases of the motor in the same direction and returns via either the upper or lower DC link. is formed.

Since the zero-axis current is generated at a frequency three times as high as the fundamental frequency of the phase current of the motor, even if it flows, it does not contribute to the effective torque of the motor and increases the copper loss of the inverter and motor. Become. In addition, if the induced voltage of the motor contains a triple frequency component, the flow of zero-axis current causes torque ripple, which causes a problem of increased noise.
Therefore, an open-winding motor drive device capable of suppressing the occurrence of zero-axis current, and a refrigeration cycle apparatus including the device are provided.

In the open winding motor drive device of the embodiment, each of the three phase windings is independent and is connected to three output terminals out of six output terminals of a motor with an open winding structure having six output terminals. a secondary inverter;
a secondary inverter connected to the remaining three output terminals of the motor;
a control unit that controls the current to be supplied to the motor and the rotational speed based on the line-to-line duty ratio of each of the primary and secondary inverters in PWM control;
a current detector that detects a current that is energized by the motor;
The control unit controls the current and rotational speed of each motor based on the line-to-line duty of each of the primary and secondary inverters, and simultaneously controls the three phases between the primary and secondary inverters. has a zero-axis current suppression unit that suppresses a zero-axis current flowing in the direction of
The zero-axis current suppressing unit outputs the first switching pattern again after outputting a first switching pattern that does not generate a zero-axis voltage that equally acts on the three phases of the motor and generates a voltage that is applied to the motor. and while outputting the first switching pattern and the second switching pattern that does not generate a zero-axis voltage and does not generate a voltage acting between phases of the motor, respectively,
A third switching pattern is inserted which generates a zero axis voltage and a voltage acting between the phases of the motor.
In addition, the refrigeration cycle apparatus of the embodiment includes a motor having an open winding structure in which three-phase windings are independent of each other and provided with six winding terminals;
and the open winding motor drive device of the embodiment.

1 is a diagram showing a circuit configuration of a motor drive system according to a first embodiment; FIG. Diagram showing waveforms of three-phase current and zero-axis current FIG. 2 is an enlarged view of a part of FIG. Functional block diagram showing the configuration of the current control section A diagram showing changes in zero-axis voltage caused by switching of the primary and secondary inverters. A diagram showing space voltage vectors corresponding to a configuration for driving a general three-phase motor Diagram showing space voltage vectors for configurations driving open winding motors A diagram showing the first and second vector patterns used in each sector by dividing the space voltage vector into six sectors. A diagram showing a vector pattern used when decreasing the zero-axis current A diagram showing a vector pattern used when increasing the zero-axis current Functional block diagram showing the configuration of the dq0/αβ0 conversion unit Functional block diagram showing the configuration of an air conditioner Diagram showing the circuit configuration of a conventional motor drive system (Part 1) Diagram showing the circuit configuration of a conventional motor drive system (Part 2) Diagram showing the circuit configuration of a conventional motor drive system (Part 3)

An embodiment will be described below with reference to FIGS. 1 to 12. FIG. FIG. 1 is a diagram showing the circuit configuration of the motor drive system of this embodiment. The motor M is assumed to be a three-phase permanent magnet synchronous motor, an induction machine, or the like, but in this embodiment, it is a permanent magnet synchronous motor. The three-phase windings of the motor M are not connected to each other and both terminals are open. That is, the motor M has six winding terminals Ua, Va, Wa, Ub, Vb, and Wb.

Each of the primary side inverter 1 and the secondary side inverter 2 is configured by connecting N-channel MOSFETs 3 as switching elements in a three-phase bridge connection, and these are connected in parallel to a DC power supply 4 . The DC power supply 4 may be one obtained by converting an AC power supply into a DC power supply. Each phase output terminal of inverter 1 is connected to winding terminals Ua, Va, Wa of motor M, and each phase output terminal of inverter 2 is connected to winding terminals Ub, Vb, Wb of motor M, respectively.

The position sensor 6 is a sensor for detecting the rotor rotation position and rotation speed of the motor M, and the current sensors 7 (U, V, W) are sensors for detecting phase currents Iu, Iv, Iw of the motor M. , corresponds to a current detector. A voltage sensor 8 detects the voltage _VDC of the DC power supply 4 .

A control device 11 receives a speed command value ω _Ref from a higher-level control device in a system that drives the motor, and performs control so that the detected motor speed ω coincides with the speed command value ω _Ref . Based on the phase currents Iu, Iv, Iw detected by the current sensor 7 and the DC voltage _VDC detected by the voltage sensor 8, the control device 11 applies switching to the gates of the FETs 3 constituting the inverters 1 and 2. Generate a signal. The control device 11 corresponds to a control section.

The current detection/coordinate conversion unit 12 converts the detected phase currents Iu, Iv, and Iw into currents Id, Iq, and I0 on the axes of d, q, and 0 used for vector control according to equation (1).

A speed/position detector 13 detects a motor speed ω and a rotor rotational position θ from signals detected by the position sensor 6 . The rotational position θ is input to the current detection/coordinate conversion section 12 and the dq0/3 phase conversion section 17 . Also, the speed/position detector 13 may be configured to estimate the speed and position from the voltage/current of the motor M. FIG. The speed control unit 14 generates and outputs a q-axis current command _IqRef by, for example, performing a PI operation on the difference between the input speed command ω _Ref and the speed ω. The d-axis current command generator 15 generates a d-axis current command value for field-weakening control from the DC voltage _VDC and the voltage amplitude Vdq of the _dq -axis, for example, by performing a PI operation on the difference between the two. output.

The current control unit 16 _generates d, q, 0-axis voltage commands _Vq , _Vd , Generate and output V0. The dq0/αβ0 conversion unit 17 converts the dq-axis voltage commands Vq, Vd, V0 into αβ-axis voltages Vα, Vβ according to equation (2), and outputs the 0-axis voltage command V0 as it is.

The space vector modulation unit 18 performs space vector calculation from the αβ-axis voltages Vα and Vβ and the 0-axis voltage V0, and obtains the phase duties D _u1 , D _v1 , and D _w1 of the inverter 1 and the phase duties D _u2 of the inverter 2. , D _v2 and D _w2 are generated and input to the PWM signal generator 19 . The PWM signal generator 19 generates switching signals and PWM signals U1±, V1±, W1±, U2±, V2±, W2± to be given to the gates of the FETs 3 constituting the inverters 1 and 2 from the input phase duty. Generate and output.

FIG. 12 shows the configuration of an air conditioner 30 to which the motor drive system of this embodiment is applied. A compressor 32 that constitutes the heat pump system 31 is configured by housing a compressing portion 33 and a motor M in the same closed iron container 35 , and a rotor shaft of the motor M is connected to the compressing portion 33 . The compressor 32, the four-way valve 36, the indoor heat exchanger 37, the decompression device 38, and the outdoor heat exchanger 39 are connected to form a closed loop by pipes serving as heat transfer medium flow paths. The compressor 32 is, for example, a rotary compressor. The air conditioner 30 is configured with the heat pump system 31 described above.

During heating, the four-way valve 36 is in the state indicated by the solid line, and the high-temperature refrigerant compressed by the compression section 33 of the compressor 32 is supplied from the four-way valve 36 to the indoor heat exchanger 37 and condensed. It is depressurized at 38 and becomes low temperature and flows to the outdoor heat exchanger 39 where it evaporates and returns to the compressor 32 . On the other hand, during cooling, the four-way valve 36 is switched to the state indicated by the dashed line. Therefore, the high-temperature refrigerant compressed by the compression section 33 of the compressor 32 is supplied from the four-way valve 6 to the outdoor heat exchanger 39 to be condensed, and then depressurized by the decompression device 38, and becomes low temperature and becomes indoor side. It flows to heat exchanger 37 where it evaporates and returns to compressor 32 . Air is blown by fans 40 and 41 to the heat exchangers 37 and 39 on the indoor side and the outdoor side, respectively. It is designed to do well.

Next, the operation of this embodiment will be described with reference to FIGS. 2 to 11. FIG. To operate the open-winding motor M, two inverters 1 and 2 apply a voltage to each terminal Ua, Va, Wa, Ub, Vb, Wb. The voltage obtained as a result of speed control and current control is divided into voltage commands to inverters 1 and 2 by dq0/αβ0 converter 17 and PWM signal generator 19 . The phase duties D _u1 , D _v1 , D _w1 of the inverter 1 and the phase duties D _u2 , D _v2 , D _w2 of the inverter 2 are energized as PWM signals having a phase difference of 180° from each other. In this manner, the two inverters 1 and 2 apply opposite-phase voltages to the motor M, thereby increasing the voltage amplitude per phase and allowing the motor to rotate at a higher speed.

However, in the configuration in which the inverters 1 and 2 share the DC link portion as in the present embodiment, the zero-axis current flowing through the three phases in the same direction poses a problem. The zero-axis current consists of a low-frequency current that flows with a frequency component three times as high as the fundamental frequency of the phase current supplied to the motor M, and a carrier-frequency component current that flows in synchronization with the switching of the inverters 1 and 2. divided into FIG. 2 shows the three-phase current and the zero axis current of the open winding motor that flow when the zero axis current is not controlled to suppress. The zero-axis current I0 pulsates with a three-fold component of the fundamental frequency of the phase currents, and this current similarly flows through the three phases, resulting in large distortions in the phase currents Iu, Iv, and Iw.

FIG. 3 is a current waveform showing an enlarged time axis of FIG. A ripple that changes at the same timing can be seen in each phase current Iu, Iv, Iw and the zero-axis current I0, which is the zero-axis current of the carrier frequency component. In this embodiment, the zero-axis current is suppressed over the entire frequency band by performing suppression corresponding to each of the three-fold component of the fundamental frequency and the carrier frequency component.

First, the suppression of the zero-axis current that flows with the three-fold component of the fundamental frequency will be described. Expression (3) is a relational expression between the dq0-axis voltage and current of the open winding motor.

Here, it can be seen that when the dq-axis currents Id and Iq flow, the zero-axis voltage V0 is generated due to the influence of the elements of the diagonal terms shown in equation (3). This is the interference from the dq axis to the 0 axis, and the zero axis current I0 flows as a result of the generation of the zero axis voltage V0.

FIG. 4 shows the detailed configuration of the current control unit 16, which includes a dq-axis current control unit 20 and a zero-axis current suppression control unit 21. As shown in FIG. The dq-axis current control unit 20 uses subtractors 22d and 22q to obtain the difference between the d-axis current command _Idref and the q-axis current command _Iqref and the d-axis current Id and the q-axis current Iq. PI control calculations are performed by the PI control units 23d and 23q. The calculation results are output as the d-axis voltage Vd and the q-axis voltage Vq.

The zero-axis current suppression control section 21 includes a P control section 21A, a resonance control section 21B, and a non-interference control section 21C. The P control unit 21A multiplies the difference between the zero-axis current command _I0Ref and the detected current I0 by a proportional gain Kp0. The resonance control unit 21B is configured to improve followability to a specific frequency, here 3ω which is three times the fundamental frequency ω of the phase current. The difference value is multiplied by the resonance gain Kr, and the difference from the integration result of the integrator 25 is taken by the subtractor 24 and input to the integrator 26 .

The integration result of integrator 26 is input to adder 27 and multiplier 28 . Multiplier 28 multiplies it with frequency 3ω, and the result is input to integrator 25 . The adder 27 adds the result of multiplying the difference value by the proportional gain Kp 0 and inputs the result to the subtractor 29 .

In order to suppress the interference component from the _dq axis to the zero axis, the non-interference control unit 21C _calculates ( 4) Calculate the interference suppression voltage _VOFF by the formula. Note that A is an adjustment coefficient.

Then, the adder 29 adds the interference suppression voltage _VOFF and the addition result of the adder 27, and outputs the zero-phase voltage V0.

Next, control for suppressing the zero-axis current of the carrier frequency component will be described. First, the principle of generation of the zero-axis current of the carrier component will be described. FIG. 5 shows the switching signals U1+, V1+, W1+ of the three-phase upper arm of the inverter 1, the switching signals U2+, V2+, W2+ of the three-phase upper arm of the inverter 2, the three-phase currents Iu, Iv, Iw, and the zero axis current. and I0. Further, the ripple V0_ripple of the zero-axis voltage generated by this switching and its magnitude are shown below.

V0_ripple is obtained by subtracting the average of the three-phase voltages of the inverter 2 from the average of the three-phase voltages of the inverter 1, as in equation (5). The phase voltages Vu1, Vv1, Vw1, Vu2, Vv2, and Vw2 are V _DC when the FET 3 is on, and 0 when the FET 3 is off.

The waveform of V0_ripple fluctuates between positive and negative depending on the switching state. there is Therefore, when V0_ripple becomes zero, the ripple of the zero-axis current I0, that is, the fluctuation of the carrier frequency component also disappears. The state of V0_ripple generation depends on the number of phases in which the FETs 3 of the inverters 1 and 2 are turned on. In other words, if the number of ON phases of inverters 1 and 2 can be made uniform, V0_ripple will not occur.

Here, in order to study the switching patterns of the inverters 1 and 2 for achieving the above purpose, the space voltage vector will be studied. FIG. 6 shows space vectors when a general motor is energized by a three-phase inverter. For example, V1 (100) indicates a state in which the U-phase upper arm is on and the V- and W-phase upper arms are off, and there are eight vectors V0 to V7.

On the other hand, FIG. 7 shows the space voltage vector of the open winding motor, and since there are two inverters, the switching pattern is 8×8=64 patterns. For the sake of convenience, V in vector notation is omitted. For example, a combination in which inverter 1 is V1 and inverter 2 is V4 is written as "14". In the space vector of an open winding motor, there are an infinite number of voltage vector patterns for outputting a certain command voltage. For example, in order to output the vectors indicated by the arrows in FIG. Output is possible by adjusting the time.

Here, considering the relationship between the zero-axis voltage and the space vector, among the 64 patterns, the vector pattern that generates the voltage applied to the motor M and does not generate the zero-axis voltage that acts equally on the three phases, that is, the ON There are 12 patterns of 15, 24, 26, 35, 31, 46, 42, 51, 53, 62, 64, and 13 in which the number of phases is the same and at least two of the turned-on phases are mismatched. FIG. 8 shows these patterns as space vectors.

FIG. 8 also shows the PWM waveform corresponding to each voltage vector. Each of the above 12 patterns is arranged in pairs at the vertices to draw a regular hexagon, which is divided into 6 sectors. For example, in order to output a vector belonging to sector 4 indicated by an arrow in FIG. 8, the energization times of voltage vectors V42 and V31 are adjusted. The PWM waveform of each voltage vector is
V42: Inverter 1 (U, V, W) = (OFF, ON, ON)
Inverter 2 (U, V, W) = (on, on, off)
V31: Inverter 1 (U, V, W) = (OFF, ON, OFF)
Inverter 2 (U, V, W) = (on, off, off)
is. Added to these are V77 for turning on all phases of inverters 1 and 2 and V00 for turning off all phases. As can be seen from the PWM waveforms of the vectors, the number of ON phases of inverters 1 and 2 are completely the same, so zero-axis voltage V0 is not generated. In other words, if the PWM switching pattern is applied, the ripple of the carrier component of the zero-axis current shown in FIGS. 4 and 5 can be suppressed.

However, if only the space voltage vector pattern that does not generate the zero-axis voltage V0 is used, it is not possible to generate the zero-axis voltage V0 output by the control for suppressing the zero-axis current that flows due to the interference described in equation (3). Therefore, in this embodiment, the following first to third vector patterns are used. The first to third vector patterns correspond to the first to third switching patterns.
<First vector pattern>
A pattern that generates a voltage to be applied to the motor M and does not generate a zero-axis voltage that acts equally on the three phases.
<Second vector pattern>
A pattern that does not generate a voltage acting between the phases of the motor M and does not generate a zero-axis voltage that acts equally on the three phases.
<Third vector pattern>
A pattern that generates a voltage acting between the phases of the motor M and a zero-axis voltage that acts equally on the three phases.

Then, the third vector pattern is inserted between the continuous output of the first vector pattern and between the output of the first vector pattern and the second vector pattern. Thereby, the zero axis voltage V0 is controlled on average.

V77 and V00 are the second vector patterns in all sectors, and in sector 4, V42 and V31 are the first vector patterns. Then, as shown in FIG. 9, when decreasing the zero-axis current I0 in the sector 4,
(1) Insert V47 between the outputs of V77 and V42.
(2) Insert V32 between the outputs of V42 and V31.
(3) Insert V01 between the outputs of V31 and V00.
In (1), (111)→(011)→(011)
(111) (111) (110)
In (2), (011)→(010)→(010)
(110) (110) (100)
In (3), (110)→(000)→(000)
(100) (100) (000)
The switching pattern changes as follows. In each of the third vector patterns V47, V32, and V01, the number of phases in which the FET 3 of the inverter 2 is turned on is one more than that of the inverter 1 . This reduces the zero axis current I0. Also, the total number of ON phases is decremented each time the vector pattern is switched.

Further, as shown in FIG. 10, when increasing the zero-axis current I0 in sector 4,
(1) Insert V72 between the outputs of V77 and V42.
(2) Insert V41 between the outputs of V42 and V31.
(3) Insert V30 between the outputs of V31 and V00.
In (1), (111)→(111)→(011)
(111) (110) (110)
In (2), (011)→(011)→(010)
(110) (100) (100)
In (3), (110)→(010)→(000)
(100) (000) (000)
The switching pattern changes as follows. In each of the third vector patterns V72, V41, and V30 in this case, the number of phases in which the FET3 of the inverter 1 is turned on is one more than that of the inverter 2. FIG. This increases the zero axis current I0. Also, as in the case of FIG. 9, the total number of ON phases is decremented each time the vector pattern is switched.

By controlling in this way, the zero-axis voltage V0_ripple is continuously generated only on the positive side and the negative side. Therefore, as shown in FIG. 5, no ripple occurs in the zero-axis current I0 due to positive and negative fluctuations in V0_ripple, and triple frequency components can be suppressed.

FIG. 11 shows the internal configuration of the space voltage vector modulation section 18 based on the control principle described above, and includes a space vector calculation section 18A and a zero-axis voltage synthesis section 18B. The input voltage commands Vα and Vβ determine the magnitudes of the two voltage vectors with a space voltage vector pattern that does not generate a zero-axis voltage in the space vector calculator 18A. To which of the six sectors the voltage belongs is determined according to the magnitudes of Vα and Vβ, and two voltage vectors are selected as the first vector pattern according to the sector. If it is sector 4, it is V42, V31, and it is calculated from the voltage commands Vα, Vβ including the magnitude of V77, V00.

The calculated voltage value of each vector and the zero-axis voltage V0 are input to the zero-axis voltage synthesizing section 18B together with the DC voltage _VDC . As shown in FIGS. 9 and 10, the zero-axis voltage synthesizing section 18B selects and inserts a voltage vector that becomes the third vector pattern according to the increase/decrease of the sectors and the zero-axis current I0. As shown in FIG. 11, in the case of sector 1, the first vector pattern is V24, V13, and the third vector pattern to be inserted when decreasing the zero axis current is V27, V14, V03. The third vector pattern to be inserted when increasing is V74, V23, V10.

9 and 10, the third vector pattern is inserted at three locations, and the total value of the voltage vectors in these three sections is the zero-axis voltage V0 output from the zero-axis voltage suppression control section 21. must match. Therefore, the magnitude of the voltage vector in each section is V0/3.
Since the magnitude of the three-phase voltage of each of the inverters 1 and 2 is obtained by the above calculation, the duties Du1, Dv1, Dw1, Du2, Dv2, and Dw2 of each phase are determined and output by dividing by the _DC voltage VDC. be.

As described above, according to the present embodiment, the three-phase windings are independent of each other, and the motor M having the open winding structure provided with the six output terminals Ua to Wb is connected to the primary inverter 1 and the secondary inverter 2. , the control device 11 controls the current and rotational speed of the motor M based on the duty between the lines of the inverters 1 and 2, and also controls the zero current of the three phases flowing in the same direction between the inverters 1 and 2. A zero axis current suppression control unit 21 for suppressing the axis current is provided.
The zero-axis current suppression control unit 21 continuously outputs the first vector pattern that does not generate the zero-axis voltage that equally acts on the three phases of the motor M and generates the voltage that is applied to the motor M, and the first vector pattern. While alternately outputting the pattern and the second vector pattern that does not generate the zero-axis voltage and does not generate the voltage acting between the phases of the motor M, the zero-axis voltage is generated and the voltage acting between the phases of the motor M is generated. Insert a third vector pattern that generates a voltage.

As a result, it is possible to suppress both the low-frequency zero-axis current that flows as a component three times the fundamental frequency of the phase current and the zero-axis current that is a carrier component that flows in synchronization with the switching of the inverters 1 and 2. 2 and the current and loss of the motor M can be reduced.

When the zero-axis current suppression control unit 21 generates a zero-axis voltage of negative polarity, the third vector pattern is such that the ON number of the FETs 3 forming the inverter 2 is equal to the ON number of the FETs 3 forming the inverter 1. When generating a zero-axis voltage of positive polarity by selecting only the vector pattern that is greater than Select only vector patterns that are greater than . As a result, it is possible to reliably suppress an increase or decrease in the zero-axis current by controlling the increase or decrease.

Further, the zero-axis current suppression control unit 21 controls the space voltage vectors, which are composed of 64 voltage vectors that are combinations of the on/off patterns of the inverters 1 and 2, centering points where two second vector patterns are located, and The points where two vector patterns are located are used as vertices to divide into six sectors, and the first and third vector patterns to be used are selected according to each sector. Accordingly, the first and third vector patterns can be appropriately selected according to various switching patterns of inverters 1 and 2. FIG.
In addition, by applying the open winding motor drive device of the present embodiment to the air conditioner 30, the air conditioning operation can be performed with high efficiency.

(Other embodiments)
The current sensor 7 may be a shunt resistor or a CT.
The AC power supply may be single-phase.
The switching elements are not limited to MOSFETs, and IGBTs, power transistors, wide bandgap semiconductors such as SiC and GaN, etc. may also be used.
You may apply to other products etc., without restricting to an air conditioner.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

In the drawings, M is an open structure winding motor, 1 is a primary side inverter 1, 2 is a secondary side inverter, 5 is a switch, 11 is a control device, and 30 is an air conditioner.

Claims (5)

a primary-side inverter connected to three output terminals among six output terminals of a motor having an open winding structure in which three-phase windings are independent of each other, and which has six output terminals;
a secondary inverter connected to the remaining three output terminals of the motor;
a control unit that controls the current to be supplied to the motor and the rotational speed based on the line-to-line duty ratio of each of the primary and secondary inverters in PWM control;
a current detector that detects a current that is energized by the motor;
The control unit controls the current and rotation speed of the motor based on the line-to-line duty of each of the primary and secondary inverters, and controls the three phases in the same direction between the primary and secondary inverters. has a zero-axis current suppression unit that suppresses the zero-axis current flowing through the
The zero-axis current suppressing unit outputs the first switching pattern again after outputting a first switching pattern that does not generate a zero-axis voltage that equally acts on the three phases of the motor and generates a voltage that is applied to the motor. and while outputting the first switching pattern and the second switching pattern that does not generate a zero-axis voltage and does not generate a voltage acting between phases of the motor, respectively,
An open-winding motor drive device that generates a zero axis voltage and inserts a third switching pattern that generates a voltage acting between the phases of the motor. The zero-axis current suppression unit is
When generating a zero-axis voltage of negative polarity, as the third switching pattern, the number of on-states of the switching elements of the upper arm that constitutes the secondary inverter is equal to the number of switching elements of the upper arm that constitutes the primary inverter. Select only the switching pattern that is greater than the ON number of the element,
When generating a zero-axis voltage of positive polarity, the third switching pattern is such that the ON number of the switching elements of the upper arm that constitutes the primary-side inverter is equal to the number of switching elements of the upper arm that constitutes the secondary-side inverter. 2. An open-winding motor drive device according to claim 1, wherein only a switching pattern in which the ON number of the elements is greater than that of the elements is selected. The zero-axis current suppressing unit is configured to:
A point where two of the second switching patterns are located is the center, and a point where two of the first switching patterns are located is the apex. 3. The open winding motor driver of claim 2, wherein the switching pattern is selected. 4. The open winding according to any one of claims 1 to 3, wherein when the third switching pattern is output a plurality of times, the total value of their amplitudes is set to be equal to the amplitude of the zero axis voltage. Line motor drive. a motor with an open winding structure in which three-phase windings are independent of each other and provided with six winding terminals;
A refrigeration cycle apparatus comprising the open winding motor drive device according to any one of claims 1 to 4.

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