WO2020178891A1

WO2020178891A1 - Motor drive device and refrigeration cycle application device

Info

Publication number: WO2020178891A1
Application number: PCT/JP2019/008046
Authority: WO
Inventors: 啓介植村; 和徳畠山; 裕一清水
Original assignee: 三菱電機株式会社
Priority date: 2019-03-01
Filing date: 2019-03-01
Publication date: 2020-09-10
Also published as: JPWO2020178891A1; JP7150137B2

Abstract

This motor drive device is provided with: an inverter (4) connected to a first motor (41) and a second motor (42) which have a permanent magnet in a rotor and driving the first motor (41) and the second motor (42); and current detection units (5, 6) for detecting a first motor current that is the motor current flowing through the first motor (41) and a second motor current that is the motor current flowing through the second motor (42). The inverter (4) drives the first motor (41) and the second motor (42) so that the current value of the motor current flowing through a motor to be controlled becomes small, said motor to be controlled being a motor having a larger current value between the first motor (41) and the second motor (42).

Description

Motor drive device and refrigeration cycle application equipment

The present invention relates to a motor drive device and a refrigeration cycle application device.

Conventionally, a single inverter device has been used to drive two or more PMSMs (Permanent Magnet Synchronous Motors).

For example, in Patent Document 1, a plurality of actuators (for example, motors) are connected in parallel to one drive unit, and the drive unit is controlled so that a drive signal capable of driving the plurality of actuators is generated. The technology is described.

JP, 2008-148415, A

However, although the technique described in Patent Document 1 drives a plurality of actuators by one drive means, consideration is given to ensuring robustness to the operating environment of the plurality of actuators connected in parallel. Has not been done.

For example, even if the motors connected in parallel have the same specifications, if the temperature inside the motor differs depending on the environment in which they are installed, for example, the induced voltage determined by the electric resistance value of the stator windings and the permanent magnet magnetic flux of the rotor Variations occur in motor constants such as constants or inductance values.

Here, the temperature dependence of the phase resistance of the motor constants will be described.
The temperature dependence of the electrical resistivity ρ is represented by the following formula (1). Since the temperature coefficient α in the formula (1) is larger than “0”, the phase resistance changes depending on the temperature rise. It is known to grow. Even if the motor currents are the same, if the phase resistance increases, the Joule loss in the winding increases, and the internal temperature of the motor rises. Then, the motor phase resistance is further increased and the internal temperature is further increased.

Next, of the motor constants, the temperature dependence of the induced voltage constant will be described.
It is known that the torque output by the motor is generally represented by the following equation (2). Here, the induced voltage constant Φ _f is a parameter that depends on the magnetic flux density of the permanent magnet of the rotor, but the magnetic flux density of the permanent magnet also depends on the temperature. Although the temperature coefficient varies depending on the material of the permanent magnet, the magnetic flux density basically decreases as the temperature rises. Therefore, the induced voltage constant Φ _f is a parameter that decreases as the temperature rises, but when the motor output torque τ _m is constant, the current value tends to increase from the following equation (2). Therefore, from the motor output torque τ _m and the induced voltage constant Φ _f , the Joule loss due to the winding resistance increases as the temperature rises. Therefore, the same tendency as the above-mentioned temperature coefficient of motor phase resistance is obtained.

Up to this point, the general phenomenon of the temperature dependence of the motor constant has been described, but this phenomenon will be described by applying it to the technique presented in Patent Document 1.
A state in which the installation environment of an actuator (for example, a motor) connected in parallel to one driving means (for example, an inverter) is different and the internal temperature before driving is different for each motor will be described.
The current advance angle β ₀ that minimizes the motor current is generally expressed by the following equation (3).

However, considering the temperature dependence of the motor constants, the motor constants of the motors connected in parallel are different, and the voltage output from the inverter is common to each motor. Even if the current minimum advance angle control satisfying the equation (3) is applied to one of the existing motors, the other motors will operate at an operating point different from the minimum current point. Since the internal temperature is stable in a state where heat generation and heat dissipation are balanced by the heat dissipation capacity (eg, thermal resistance to air) or heat capacity of the motor, the increase/decrease tendency of the motor current is similarly stabilized by a certain constant internal temperature balance. However, in each of the motors connected in parallel, an imbalance occurs in the electric current and the internal temperature. In this case, in the motor having the highest internal temperature, there is a possibility of approaching or exceeding the limit temperature of the insulating material of the winding, which makes it difficult to secure reliability as a motor drive device.

Therefore, it is an object of one or more aspects of the present invention to improve drive reliability of a motor connected in parallel to one inverter.

The motor drive device according to one aspect of the present invention is connected to a first motor and a second motor having a permanent magnet in a rotor, and is connected to an inverter that drives the first motor and the second motor, and the first motor. A first motor current, which is a flowing motor current, and a current detecting unit, which detects a second motor current, which is a motor current flowing through the second motor, and wherein the inverter is one of the first motor and the second motor. The first motor and the second motor are driven so that the current value of the motor current flowing through the control target motor, which is the motor having the larger current value, becomes smaller.

According to one or more aspects of the present invention, it is possible to improve the drive reliability of the motors connected in parallel to one inverter.

It is a circuit diagram which shows schematic the motor drive device which concerns on Embodiment 1 and 2. It is a functional block diagram which shows the structure of the control part in Embodiments 1 and 2. (A) to (c) are diagrams showing the operation of the PWM signal generation unit of FIG. It is a graph which shows the current value of the motor current of the 1st motor, and the current value of the motor current of the 2nd motor. It is a flowchart which shows operation|movement in an advance angle correction|amendment part. It is a vector figure for demonstrating advance angle correction value and advance phase angle. An operation example of the first motor and the second motor will be described. It is a circuit block diagram of the heat pump apparatus which concerns on Embodiment 3. It is a Moriel diagram about the state of the refrigerant of the heat pump apparatus shown in FIG.

A motor drive device according to an embodiment and a refrigeration cycle application device including the same will be described below with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

Embodiment 1.
FIG. 1 is a circuit diagram schematically showing a motor drive device 100 according to the first embodiment.
The motor drive device 100 is for driving the first motor 41 and the second motor 42. Here, the 1st motor 41 and the 2nd motor 42 are permanent magnet synchronous motors which have a permanent magnet in a rotor.

The illustrated motor drive device 100 includes a rectifier 2, a smoothing unit 3, an inverter 4, an inverter current detection unit 5, a motor current detection unit 6, an input voltage detection unit 7, a connection switching unit 8, and a control unit. And 10.

The rectifier 2 rectifies the AC power from the AC power supply 1 to generate DC power.
The smoothing portion 3 is composed of a capacitor or the like, smoothes the DC power from the rectifier 2, and supplies it to the inverter 4.

The AC power supply 1 is a single-phase power supply in the example of FIG. 2, but may be a three-phase power supply. If the AC power supply 1 is three-phase, a three-phase rectifier is also used as the rectifier 2.

As the capacitor of the smoothing portion 3, an aluminum electrolytic capacitor having a large capacitance is generally used, but a film capacitor having a long life may be used. Further, a capacitor having a small electrostatic capacity may be used to suppress the harmonic current of the current flowing through the AC power supply 1.

Further, a reactor (not shown) may be inserted between the AC power supply 1 and the smoothing portion 3 in order to suppress the harmonic current or improve the power factor.

The inverter 4 receives the voltage of the smoothing unit 3 as an input and outputs three-phase AC power with variable frequency and voltage value.
A first motor 41 and a second motor 42 are connected in parallel to the output of the inverter 4, and the inverter 4 drives the first motor 41 and the second motor 42. Specifically, the inverter 4 drives the first motor 41 and the second motor 42 by applying a three-phase AC voltage to the first motor 41 and the second motor 42.

The inverter 4 generates a three-phase AC voltage by switching the DC voltage with a plurality of switching elements. Each of the plurality of switching elements is preferably a semiconductor switching element. Here, as the semiconductor switching element constituting the inverter 4, an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is often used.

A freewheeling diode (not shown) may be connected in parallel with the semiconductor switching element for the purpose of suppressing surge voltage due to switching of the semiconductor switching element.
You may use the parasitic diode of a semiconductor switching element as a free wheeling diode. In the case of a MOSFET, it is possible to realize the same function as that of a free wheeling diode by turning on the MOSFET at the timing of circulation.

The material constituting the semiconductor switching element is not limited to silicon Si, and wide bandgap semiconductors such as silicon carbide SiC, gallium nitride GaN, gallium oxide Ga ₂ O ₃ , and diamond can be used. By using a semiconductor, low loss and high speed switching can be realized.

The connection switching unit 8 switches the connection state between at least one of the first motor 41 and the second motor 42 and the inverter 4 between connection and disconnection.
The connection switching unit 8 includes three opening/closing units 9 in the illustrated example. The opening/closing unit 9 can connect or disconnect the second motor 42 and the inverter 4, and by opening/closing the opening/closing unit 9, it is possible to switch the number of motors to be operated at the same time.
As the opening/closing unit 9, an electromagnetic contactor such as a mechanical relay or a contactor may be used instead of the semiconductor switching element. In short, any one may be used as long as it has a similar function. Similar to the above, the semiconductor switching element can realize low loss and high speed switching by using a wide band gap semiconductor.

In the illustrated example, the connection switching unit 8 is provided between the second motor 42 and the inverter 4, but the first embodiment is not limited to such an example.
Although not shown, a connection switching unit may be provided between the first motor 41 and the inverter 4. Further, a connection switching unit may be provided both between the second motor 42 and the inverter 4 and between the first motor 41 and the inverter 4.

In the illustrated example, two motors are connected to the inverter 4, but three or more motors may be connected to the inverter 4. When connecting three or more motors to the inverter 4, a connection switching unit similar to the connection switching unit 8 may be provided between each of all the motors and the inverter 4. Alternatively, a connection switching unit similar to the connection switching unit 8 may be provided between the inverter 4 and only some of the motors.

The inverter current detector 5 detects the current flowing through the inverter 4. In the illustrated example, the inverter current detector 5, the resistance _R u, each into three switching elements of the lower arm of inverter 4 connected in _series, R v, the voltage across _V Ru of _{R _w,} V _Rv, the _{V Rw} based on, inverter current _i U_all a current of the three phases of the inverter _{_4, i} _{v_all,} i w_all are obtained, respectively.

The motor current detector 6 detects the current of the first motor 41. The motor current detection unit 6 includes three current transformers that respectively detect the phase currents _{iu_m} , _{iv_m} , and _{iw_m} that are the currents of the three phases.
As will be described later, the inverter current detection unit 5 and the motor current detection unit 6 constitute a current detection unit that detects the motor current flowing through the first motor 41 and the second motor 42. The motor current flowing through the first motor 41 is also referred to as a first motor current, and the motor current flowing through the second motor 42 is also referred to as a second motor current.

The input voltage detection unit 7 detects the DC bus voltage V _dc , which is the input voltage of the inverter 4.

The control unit 10 is based on the current value of the current detected by the inverter current detection unit 5, the current value of the current detected by the motor current detection unit 6, and the voltage value of the voltage detected by the input voltage detection unit 7. , And outputs a signal for operating the inverter 4.

In the above example, the inverter current detection unit 5 detects the current of each of the three phases of the inverter 4 by the three resistors connected in series with the switching element of the lower arm of the inverter 4, but instead The current of each of the three phases of the inverter 4 may be detected by a resistor connected between the common connection point of the switching elements of the lower arm and the negative electrode of the smoothing unit 3.

Further, in addition to the motor current detection unit 6 that detects the current of the first motor 41, a motor current detection unit that detects the current of the second motor 42 may be provided. In this case, the motor current detection unit 6 and the motor current detection unit that detects the current of the second motor 42 constitute a current detection unit that detects the motor current flowing through the first motor 41 and the second motor 42.

Instead of using the current transformer, a Hall element may be used for detecting the motor current, and a configuration for calculating the current value from the voltage across the resistor may be used.
Similarly, for detecting the inverter current, a current transformer, a Hall element, or the like may be used instead of the configuration in which the current value is calculated from the voltage across the resistor.

The control unit 10 can be realized by a processing circuit. The processing circuit may be configured by dedicated hardware, may be configured by software, or may be configured by a combination of hardware and software. When configured with software, the control unit 10 is configured with a microcomputer including a CPU (Central Processing Unit), a DSP (Digital Signal Processor), and the like.

FIG. 2 is a functional block diagram showing the configuration of the control unit 10.
As shown in the figure, the control unit 10 includes an operation command unit 11, a subtraction unit 12, coordinate conversion units 13m and 13l, speed estimation units 14m and 14l, integration units 15m and 15l, and a motor control unit 16. It has a pulsation compensation control unit 17, a coordinate conversion unit 18, a PWM signal generation unit 19, and an advance angle correction unit 20.

The operation command unit 11 generates and outputs a motor rotation speed command value ω _m ^* . The operation command unit 11 also generates and outputs a switching control signal S _w for controlling the connection switching unit 8.

The subtraction unit 12 subtracts the phase currents i _{u_m} , i _{v_m} , and i _{w_m} of the first motor 41 from the phase currents i _{u_all} , i _{v_all} , and i _{w_all} of the inverter 4 detected by the inverter current detection unit 5 to _generate the second current. The phase currents _{iu_sl} , _{iv_sl} , and _{iw_sl} of the motor 42 are _obtained .
This is the phase current _i u_M of the first motor _41, i _{v_m, i w_m} and phase currents _i U_sl of the second motor _{_42, i} _{v_sl,} i w_sl the sum inverter phase currents _i U_all _{of, i v_all, i} _{It uses} the relationship of being equal to _{w_all} .

The coordinate conversion unit 13 m coordinates the phase currents i _{u_m} , _{iv_m} , and i _{w_m} of the first motor 41 from the stationary three-phase coordinate system to the rotating two-phase coordinate system by using the phase estimation value θ _m of the first motor 41 described later. After conversion, the dq axis currents i _{d_m} and i _{q_m} of the first motor 41 are _obtained . It can be said that the estimated phase value θ _m is a magnetic pole position estimated value of the first motor 41.

Coordinate conversion unit 13l the phase current _i U_sl of the second motor 42 using the phase estimate theta _sl of the second motor 42 described _later, i _{V_sl,} coordinates the rotation two-phase coordinate system _{i W_sl} from the stationary three-phase coordinate system The conversion is performed to obtain the dq-axis currents i _{d — sl} and i _{q —} _sl of the second motor 42. It can be said that the phase estimated value θ _sl is a magnetic pole position estimated value of the second motor 42.

The first velocity estimation unit 14m _obtains the rotation speed estimation value ω _m of the first motor 41 based on the dq axis currents i _{d_m} and i _{q_m} and the dq axis voltage command values v _d ^* and v _q ^* described later.
Similarly, the second velocity estimation unit _{14l sets} the rotation speed estimation value ω _sl of the second motor 42 based on the dq axis currents i _{d_sl} and i _{q_sl} and the dq axis voltage command values v _d ^* and v _q ^* described later. Ask.

The integrator 15m integrates the rotation speed estimation value ω _m of the first motor 41 to obtain the phase estimation value θ _m of the first motor 41.
Similarly, the integrating unit 15l obtains the phase estimated value θ _sl of the second motor 42 by integrating the rotation speed estimated value ω _sl of the second motor 42.

For the estimation of the rotation speed and the phase, for example, the method shown in Japanese Patent No. 4672236 can be used, but any method can be used as long as the rotation speed and the phase can be estimated. May be. Alternatively, a method of directly detecting the rotation speed or the phase may be used.

The motor control unit 16 is based on the dq-axis currents i _{d_m} and i _{q_m} of the first motor 41, the estimated rotation speed ω _{m of} the first motor 41, and the pulsation compensation current command value _isl ^* described later. Axis voltage command values v _d ^* and v _q ^* are calculated.

The coordinate conversion unit 18 is based on the phase estimation value θ _m of the first motor 41, the dq-axis voltage command values v _d ^* and v _q ^*, and the advance angle correction value β'from the advance angle correction unit 20 described later. The applied voltage phase θ _v is obtained. Then, the coordinate conversion unit 18 converts the dq-axis voltage command values v _d ^* and v _q ^* from the rotating two-phase coordinate system to the stationary three-phase coordinate system based on the applied voltage phase θ _v , and the stationary three-phase coordinates. The voltage command values v _u ^* , v _v ^* , v _w ^* on the system are obtained.

The applied voltage phase θ _v is the lead phase angle θ _f obtained by the following equation (4) from, for example, the dq axis voltage command values v _d ^* and v _q ^* and the advance angle correction value β'. It is obtained by adding to the estimated phase value θ _m of the motor 41.

An example of the phase estimation value θ _m , the lead phase angle θ _f , and the applied voltage phase θ _v is shown in FIG. 3A, and the voltage command values v _u ^* , v _v ^* , v _w obtained by the coordinate conversion unit 18. An example of ^* is shown in FIG.

The PWM signal generation unit 19 has the input voltage V _dc and the voltage command values v _u ^* , v _v ^* , v _w ^*, and the PWM signals UP, VP, WP, UN, VN, WN shown in FIG. 3 (c). To generate.
The PWM signals UP, VP, WP, UN, VN, WN are supplied to the inverter 4 and used for controlling the switching elements.

The inverter 4 is provided with a drive circuit (not shown) that generates drive signals for driving the switching elements of the corresponding arms based on the PWM signals UP, VP, WP, UN, VN, WN.

By controlling ON/OFF of the switching element of the inverter 4 based on the PWM signals UP, VP, WP, UN, VN, WN, the inverter 4 outputs a three-phase AC voltage with variable frequency and voltage value. , And can be applied to the first motor 41 and the second motor 42.

The voltage command values v _u ^* , v _v ^* , and v _w ^* are sine waves in the example shown in FIG. 3 (b), but the voltage command values may be superposed with third harmonics. , The waveform may be any as long as it is possible to drive the first motor 41 and the second motor 42.

If the motor control unit 16 is configured to generate a voltage command based only on the dq-axis currents i _{d_m} , i _{q_m} and the estimated rotation speed ω _{m of} the first motor 41, the first motor 41 is appropriately controlled. On the other hand, the second motor 42 only operates according to the voltage command value generated for the first motor 41, and is in a state where it is not directly controlled.

Therefore, the first motor 41 and the second motor 42 operate in a state in which the phase estimated value θ _m and the phase estimated value θ _sl are accompanied by an error, and the error is particularly remarkable in the low speed range.
If an error occurs, current pulsation of the second motor 42 will occur, and there is a risk of loss of step due to out-of-step of the second motor 42 and heat generation due to excessive current. Further, the circuit may be cut off in response to the excessive current, the motor may stop, and the load cannot be driven.

The pulsation compensation control unit 17 is provided to solve such a problem, and includes the q-axis current i _{q_sl} of the second motor 42, the phase estimated value θ _m of the first motor 41, and the second motor. Using the phase estimated value θ _{sl of} 42, the pulsation compensation current command value _isl ^* for suppressing the current pulsation of the second motor 42 is output.

The pulsation compensation current command value _isl ^* determines the phase relationship between the first motor 41 and the second motor 42 from the phase estimated value θ _{m of} the first motor 41 and the phase estimated value θ _sl of the second motor 42. The pulsation of the q-axis current i _{q_sl} corresponding to the torque current of the second motor 42 is determined based on the determination result.

The motor control unit 16 performs a proportional integration calculation on the deviation between the rotation speed command value ω _m ^* of the first motor 41 and the rotation speed estimated value ω _{m of} the first motor 41, and q of the first motor 41. The axis current command value _{Iq_m} ^* is obtained.

On the other hand, the d-axis current of the first motor 41 is an exciting current component, and by changing the value, it is possible to control the current phase and drive the first motor 41 with a stronger magnetic flux or a weaker magnetic flux. Becomes Using the characteristics, the pulsation compensation current command value i _sl ^* mentioned above, by reflecting the d-axis current command value I _{D_M} of the first motor 41 ^*, to control the current phase, thereby suppressing the pulsation It is possible to

The motor control unit 16 determines the dq-axis voltage command based on the dq-axis current command values I _{d_m} ^* and I _{q_m} ^* calculated as described above and the dq-axis currents i _{d_m} and i _{q_m} calculated by the coordinate conversion unit 13 m. The values v _d ^* and v _q ^* are obtained. That is, the d-axis current command value I _{d_m} ^* and the d-axis current _{id_m} are proportionally integrated to obtain the d-axis voltage command value v _d ^* , and the q-axis current command value I _{q_m} ^* and the q-axis The q-axis voltage command value v _q ^* is obtained by performing a proportional-plus-integral calculation on the deviation from the current i _{q_m} .

The motor control unit 16 and the pulsation compensation control unit 17 may have any configuration as long as the same functions can be realized.

By performing the control as described above, it becomes possible to drive the first motor 41 and the second motor 42 with one inverter 4 so that the pulsation does not occur in the second motor 42.

Advance angle correction unit 20, the phase current _i u_M of the first motor _41, i _{v_m,} and _{i w_m,} the phase current _i U_sl of the second motor _{_42,} i _{v_sl,} as input and _{i W_sl,} advance correction value beta ' Is output.

Here, regarding the operation of the advance angle correction unit 20 when the first motor 41 and the second motor 42 have the same specifications and their internal temperatures are different, in other words, when their motor constants are different, FIG. Will be described with reference to.

As shown in FIG. 4, when the current value of the motor current of the second motor 42 is larger than the current value of the motor current of the first motor 41, the lead angle correction unit 20 determines that the second motor 42 The lead angle correction value β′ is specified so that the current value becomes small. As a result, the motor current of the second motor 42 tends to decrease, but the first motor 41 moves to an operating point different from the current minimum point due to variations in motor constants. The current tends to increase.

The lead angle correction unit 20 sequentially calculates the current lead angle correction value β′ so that the current value of the first motor 41 and the current value of the second motor 42 match. As a result, the Joule loss in each motor is made uniform, and the internal temperature of each motor is also made uniform. Therefore, imbalance of the internal temperature of the motor can be suppressed, and excessive heat generation in one motor can be suppressed.

FIG. 5 is a flowchart showing the operation of the advance angle correction unit 20.
First, the advance angle correction unit 20 determines whether or not the current value of the motor current flowing through the first motor 41 is equal to the current value of the motor current flowing through the second motor 42 (S10). When the current value of the motor current flowing through the first motor 41 is equal to the current value of the motor current flowing through the second motor 42 (Yse in S10), the process proceeds to step S11 and the motor current of the first motor 41 When the current value is different from the motor current value of the second motor 42 (No in S10), the process proceeds to step S12.
Here, the lead angle correction unit 20 may use any of the U-phase, V-phase, and W-phase as the motor current, and regarding the format of the current value, the peak value may be used, and the execution value may be used. May be used. However, in the first motor 41 and the second motor 42, the phases and types of currents to be compared are the same.

In step S11, the advance angle correction unit 20 does not correct the advance angle. In other words, the lead angle correction unit 20 sets the lead angle correction value β′ to “0”. In this case, for example, the first motor 41 and the second motor 42 are driven at the operating point that is the minimum current point of the first motor 41.

In step S12, the lead angle correction unit 20 determines whether or not the current value of the motor current flowing through the first motor 41 is larger than the current value of the motor current flowing through the second motor 42. When the current value of the motor current of the first motor 41 is larger than the current value of the motor current of the second motor 42 (Yes in S12), the process proceeds to step S13, and the current of the motor current of the first motor 41. When the value is not larger than the current value of the motor current of the second motor 42 (No in S12), the process proceeds to step S14.

In step S13, the lead angle correction unit 20 determines the first motor 41 as the control target motor. Then, the process proceeds to step S15.

In step S14, since the current value of the motor current flowing through the second motor 42 is larger than the current value of the motor current flowing through the first motor 41, the advance angle correction unit 20 controls the second motor 42. Determine as a motor. Then, the process proceeds to step S15.

In step S15, the advance angle correction unit 20 specifies the advance angle correction value β'so that the current value of the motor current flowing through the controlled target motor becomes small.

The lead angle correction unit 20 may specify the lead angle correction value β′ by using a search method such as a hill climbing method. Specifically, the advance angle correction unit 20 confirms the increase or decrease in the current value of the motor current with respect to the operation of the advance angle correction value β′ from the current value of the motor current and the advance angle correction value β′ in the past control cycle. Then, the advance angle correction value β′ may be specified so that the current value of the motor current of the control target motor tends to decrease.
It should be noted that the lead angle correction unit 20 does not have to use the above-described exploratory method as long as the lead angle correction value β′ with which the current value of the motor current of the control target motor tends to decrease is obtained.

When the lead angle correction value β′ is determined as described above, the coordinate conversion unit 18 determines the lead phase angle θ _f obtained by the above equation (4) as the phase estimated value θ _m of the first motor 41. To calculate the applied voltage phase θ _v .

FIG. 6 is a vector diagram for explaining the advance angle correction value β'and the advance phase angle θ _f .
tan ^-1 (v _{q_m} ^* / v _{d_m} ^* ) determines the _{declination of} the d-axis voltage command value v _{d_m} ^* and the q-axis voltage command value v _{q_m} ^* output by the inverter 4 in order to control the first motor 41. It represents.
FIG. 6 shows a case where the position estimated value θ _sl of the second motor 42 has a lag phase with respect to the rotation position estimated value θ _{m of} the first motor 41.

Here, when controlling the second motor 42, the advance angle that minimizes the current is virtually defined as tan ⁻¹ (v _{q_sl} ^* /v _{d_sl} ^* ). When the advance angle is tan ^-1 (v _{q_m} ^* / v _{d_m} ^* ) at which the first motor 41 has the minimum current advance angle, the advance is excessive with respect to the second motor 42. At this time, the current value of the motor current of the second motor 42 becomes larger than the current value of the motor current of the first motor 41.

Therefore, it is possible to suppress the current imbalance between the motors by operating the advance correction value β′ according to the magnitude relation of the currents flowing through the first motor 41 and the second motor 42. In the case shown in FIG. 6, the lead angle correction value β′ is specified on the delay side with respect to the lead angle tan ⁻¹ (v _{q_m} ^* /v _{d_m} ^* ).

As described above, according to the flowchart shown in FIG. 5, the inverter 4 operates when the current value of the motor current flowing through the first motor 41 is different from the current value of the motor current flowing through the second motor 42. Of the first motor 41 and the second motor 42, the first motor 41 and the second motor 42 are driven so that the current value of the motor current flowing through the control target motor, which is the motor having the larger current value, becomes smaller. be able to.

Here, the control unit 10 controls the inverter 4 so that the current value of the motor current flowing through the controlled motor is reduced by changing the phase of the three-phase AC voltage output from the inverter 4. Specifically, the control unit 10 flows to the controlled target motor by correcting the lead phase angle in the applied voltage phase for calculating the voltage command value used to generate the PWM signal output to the inverter 4. The current value of the motor current is reduced.

Next, an operation example of the first motor 41 and the second motor 42 will be described with reference to FIG. 7.
For example, as shown in FIG. 7, the opening/closing unit 9 of the connection switching unit 8 is turned off to drive only the first motor 41, and then the inverter 4 is once stopped. Then, the case where the opening/closing section 9 of the connection switching section 8 is turned on and the inverter 4 is started will be described.

In the case of the operation as shown in FIG. 7, at timing A, the first motor 41 was driven up to that point, but the second motor 42 was stopped. Therefore, the internal temperature of the second motor 42 is equal to the first motor 41. Is assumed to be lower than the internal temperature of. In other words, the motor constants of the first motor 41 and the second motor 42 are substantially different depending on the temperature characteristics.

If the first motor 41 and the second motor 42 are driven after the timing A in such a state, the phases of the first motor 41 and the second motor 42 that minimize the current are different as described above. An imbalance will occur in the current flowing through. Here, as described above, the control unit 10 controls so that the current flowing through each motor becomes uniform. As a result, the Joule loss generated in the first motor 41 and the second motor 42 can be made uniform, and excessive heat generation inside the motor can be suppressed.

As described above, according to the first embodiment, it is possible to correct the imbalance of the motor current between the first motor 41 and the second motor 42 connected in parallel, and suppress the imbalance. Therefore, since the imbalance of Joule loss due to the motor current can be suppressed, the heat generation of the motor and the imbalance of the internal temperature of the motor can be suppressed.

Embodiment 2.
As shown in FIG. 1, the motor drive device 200 according to the second embodiment includes a rectifier 2, a smoothing unit 3, an inverter 4, an inverter current detection unit 5, a motor current detection unit 6, and an input. The voltage detection unit 7, the connection switching unit 8, and the control unit 21 are provided.
The rectifier 2, the smoothing unit 3, the inverter 4, the inverter current detection unit 5, the motor current detection unit 6, the input voltage detection unit 7, and the connection switching unit 8 of the motor drive device 200 according to the second embodiment are the first embodiment. It is the same as the rectifier 2, the smoothing unit 3, the inverter 4, the inverter current detection unit 5, the motor current detection unit 6, the input voltage detection unit 7, and the connection switching unit 8 of the motor drive device 100 according to 1.

As shown in FIG. 2, the control unit 21 in the second embodiment includes an operation command unit 11, a subtraction unit 12, coordinate conversion units 13m and 13l, speed estimation units 14m and 14l, and an integration unit 15m. , 15l, a motor control unit 16, a pulsation compensation control unit 17, a coordinate conversion unit 18, a PWM signal generation unit 19, and an advance angle correction unit 22.
The operation command unit 11, the subtraction unit 12, the coordinate conversion unit 13m, 13l, the speed estimation unit 14m, 14l, the integration unit 15m, 15l, the motor control unit 16, the pulsation compensation control unit 17, and the control unit 21 of the second embodiment. The coordinate conversion unit 18 and the PWM signal generation unit 19 are the operation command unit 11, the subtraction unit 12, the coordinate conversion unit 13m, 13l, the speed estimation unit 14m, 14l, the integration unit 15m, 15l of the control unit 10 in the first embodiment. The same as the motor controller 16, the pulsation compensation controller 17, the coordinate converter 18, and the PWM signal generator 19.

The lead angle correction unit 22 performs substantially the same processing as the lead angle correction unit 20 in the first embodiment, but the criterion for determining that the lead angle correction is not performed is the lead angle correction unit 20 in the first embodiment. Different.

In the first embodiment, the advance correction value β'is generated so that the current values of the motor currents of the first motor 41 and the second motor 42 match. However, in consideration of variations in the detection circuits such as the inverter current detection unit 5 and the motor current detection unit 6, for example, under actual conditions, the current values of the motor currents of the first motor 41 and the second motor 42 are completely reduced. Is difficult to match. Therefore, the allowable value of the difference between the current values of the motor currents of the first motor 41 and the second motor 42 will be described below.

Depending on the type of insulating material used for the motor winding, for example, the Electrical Appliance and Material Safety Law stipulates the internal temperature, which is a maximum of 165 ° C. However, in the first embodiment, since the internal temperature of the motor is not directly measured, the imbalance of the current value of the motor current, in other words, the difference in the current value of the motor current between the motors will be described.

If the internal temperature of the first motor 41 and the internal temperature of the second motor 42 are uniformly 165 ° C., the magnetic flux density of the permanent magnets arranged in the rotor decreases, and the magnetic flux density decreases according to the temperature. It is known that the coefficient K _Φ is generally in the vicinity of −0.2 to −0.1% / ° C.

When K _Φ = −0.2% / ° C. and magnet temperature T = 165 ° C., the rate of decrease in magnetic flux density of the permanent magnet = −0.2 × 165 = 33%.
A 33% decrease in the magnetic flux density of the permanent magnet is synonymous with a 33% decrease in the induced voltage constant Φ _f in the motor constant. Therefore, from the above equation (2), the required current when outputting the required torque is increased by about 33%. Therefore, as one index, it is possible to keep the temperature inside the motor at 165° C. or lower by setting the unbalance amount of the motor current to 33% or lower.

Therefore, the lead angle correction unit 22 in the second embodiment determines that the difference between the current value of the motor current of the first motor 41 and the current value of the motor current of the second motor 42 is the first value in step S10 of FIG. When the current value of the motor current of the one motor 41 is 33% or less, the process proceeds to step S11, and when it exceeds 33%, the process proceeds to step S12.

As described above, according to the second embodiment, the control unit 21 sets the difference between the current value of the motor current flowing through the first motor 41 and the current value of the motor current flowing through the second motor 42 within a predetermined range. By driving the first motor 41 and the second motor 42 so that the current value of the motor current flowing through the controlled motor becomes smaller when the above value is exceeded, the internal temperature of the first motor 41 and the first The internal temperature of the two motors 42 can be kept within a predetermined temperature range.

Embodiment 3.
In the third embodiment, an example of a circuit configuration of a heat pump device as a refrigeration cycle application device will be described.
FIG. 8 is a circuit configuration diagram of the heat pump device 900 according to the third embodiment.
FIG. 9 is a Mollier diagram for the refrigerant state of the heat pump device 900 shown in FIG. In FIG. 9, the horizontal axis represents the specific enthalpy and the vertical axis represents the refrigerant pressure.

In the heat pump device 900, a compressor 901, a heat exchanger 902, an expansion mechanism 903, a receiver 904, an internal heat exchanger 905, an expansion mechanism 906, and a heat exchanger 907 are sequentially connected by piping, and a refrigerant Is provided with a main refrigerant circuit 908. In the main refrigerant circuit 908, a four-way valve 909 is provided on the discharge side of the compressor 901 so that the circulation direction of the refrigerant can be switched.

The heat exchanger 907 has a first portion 907a and a second portion 907b, valves (not shown) are connected to these, and the flow of the refrigerant is controlled according to the load of the heat pump device 900. For example, when the load of the heat pump device 900 is relatively large, the refrigerant flows through both the first portion 907a and the second portion 907b, and when the load of the heat pump device 900 is relatively small, the first portion 907a and the second portion 907a. Refrigerant is flowed only to one of the portions 907b, for example, only to the first portion 907a.

The first portion 907a and the second portion 907b are provided with

fans

910a and 910b corresponding to the respective portions in the vicinity thereof. The

fans

910a and 910b are driven by separate motors. For example, the first motor 41 and the second motor 42 described in the first or second embodiment are used to drive the

fans

910a and 910b, respectively. The fan 910a is also referred to as a first fan, and the fan 910b is also referred to as a second fan.

Further, the heat pump device 900 includes an injection circuit 912 that connects between the receiver 904 and the internal heat exchanger 905 to the injection pipe of the compressor 901 by piping. An expansion mechanism 911 and an internal heat exchanger 905 are connected to the injection circuit 912.

A water circuit 913 through which water circulates is connected to the heat exchanger 902. Note that the water circuit 913 is connected to a water-using device such as a water heater, a radiator, or a radiator such as floor heating.

First, the operation of the heat pump device 900 during the heating operation will be described. During the heating operation, the four-way valve 909 is set in the solid line direction. The heating operation includes not only heating used for air conditioning but also heating of water for hot water supply.

The gas-phase refrigerant (high temperature and high pressure in the compressor 901) (point 1 in FIG. 9) is discharged from the compressor 901 and is heat-exchanged and liquefied in the heat exchanger 902 which is a condenser and a radiator (FIG. 9). Point 2). At this time, the heat radiated from the refrigerant warms the water circulating in the water circuit 913 and is used for heating or hot water supply.

The liquid-phase refrigerant liquefied by the heat exchanger 902 is decompressed by the expansion mechanism 903 and becomes a gas-liquid two-phase state (point 3 in FIG. 9). The refrigerant in the gas-liquid two-phase state in the expansion mechanism 903 is heat-exchanged with the refrigerant sucked into the compressor 901 by the receiver 904, cooled, and liquefied (point 4 in FIG. 9). The liquid-phase refrigerant liquefied by the receiver 904 branches into the main refrigerant circuit 908 and the injection circuit 912 and flows.

The liquid-phase refrigerant flowing through the main refrigerant circuit 908 is further cooled by exchanging heat with the refrigerant flowing through the injection circuit 912, which has been decompressed by the expansion mechanism 911 and is in a gas-liquid two-phase state, by the internal heat exchanger 905 (FIG. 9). Point 5). The liquid-phase refrigerant cooled by the internal heat exchanger 905 is decompressed by the expansion mechanism 906 and becomes a gas-liquid two-phase state (point 6 in FIG. 9). The refrigerant in the gas-liquid two-phase state in the expansion mechanism 906 is heat-exchanged with the outside air in the heat exchanger 907 serving as an evaporator and heated (point 7 in FIG. 9).
Then, the refrigerant heated by the heat exchanger 907 is further heated by the receiver 904 (point 8 in FIG. 9) and drawn into the compressor 901.

On the other hand, as described above, the refrigerant flowing through the injection circuit 912 is decompressed by the expansion mechanism 911 (point 9 in FIG. 9) and heat-exchanged by the internal heat exchanger 905 (point 10 in FIG. 9). The gas-liquid two-phase refrigerant (injection refrigerant) that has been heat-exchanged in the internal heat exchanger 905 flows into the compressor 901 from the injection pipe of the compressor 901 in the gas-liquid two-phase state.

In the compressor 901, the refrigerant sucked from the main refrigerant circuit 908 (point 8 in FIG. 9) is compressed and heated to an intermediate pressure (point 11 in FIG. 9).
The injection refrigerant (point 10 in FIG. 9) merges with the refrigerant (point 11 in FIG. 9) compressed and heated to the intermediate pressure, and the temperature drops (point 12 in FIG. 9).
Then, the refrigerant whose temperature has dropped (point 12 in FIG. 9) is further compressed and heated to become high temperature and high pressure, and is discharged (point 1 in FIG. 9).

When the injection operation is not performed, the opening degree of the expansion mechanism 911 is fully closed. That is, when the injection operation is performed, the opening degree of the expansion mechanism 911 is larger than a certain value, but when the injection operation is not performed, the opening degree of the expansion mechanism 911 is made smaller than the certain value described above. .. As a result, the refrigerant does not flow into the injection pipe of the compressor 901.
Here, the opening degree of the expansion mechanism 911 is electronically controlled by a control unit configured by a microcomputer or the like.

Next, the operation of the heat pump device 900 during the cooling operation will be described. During the cooling operation, the four-way valve 909 is set in the broken line direction. This cooling operation includes not only cooling used for air conditioning but also cooling of water or freezing of food.

The gas-phase refrigerant (high temperature and high pressure in the compressor 901) (point 1 in FIG. 9) is discharged from the compressor 901 and is heat-exchanged and liquefied in the heat exchanger 907 which is a condenser and a radiator (FIG. 9 ). Point 2). The liquid-phase refrigerant liquefied by the heat exchanger 907 is decompressed by the expansion mechanism 906 to be in a gas-liquid two-phase state (point 3 in FIG. 9). The refrigerant in the gas-liquid two-phase state by the expansion mechanism 906 is heat-exchanged by the internal heat exchanger 905, cooled and liquefied (point 4 in FIG. 9). In the internal heat exchanger 905, the refrigerant that has become a gas-liquid two-phase state in the expansion mechanism 906 and the liquid-phase refrigerant that has been liquefied in the internal heat exchanger 905 are decompressed in the expansion mechanism 911 to become a gas-liquid two-phase state. Heat is exchanged with the refrigerant (point 9 in FIG. 9). The liquid-phase refrigerant (point 4 in FIG. 9) that has undergone heat exchange in the internal heat exchanger 905 branches into the main refrigerant circuit 908 and the injection circuit 912 and flows.

The liquid-phase refrigerant flowing through the main refrigerant circuit 908 is heat-exchanged with the refrigerant sucked into the compressor 901 by the receiver 904 and further cooled (point 5 in FIG. 9). The liquid-phase refrigerant cooled by the receiver 904 is decompressed by the expansion mechanism 903 and becomes a gas-liquid two-phase state (point 6 in FIG. 9). The refrigerant in the gas-liquid two-phase state by the expansion mechanism 903 is heat-exchanged by the heat exchanger 902, which is an evaporator, and is heated (point 7 in FIG. 9). At this time, the refrigerant absorbs heat, so that the water circulating in the water circuit 913 is cooled and used for cooling, cooling, freezing, or the like.
Then, the refrigerant heated by the heat exchanger 902 is further heated by the receiver 904 (point 8 in FIG. 9) and drawn into the compressor 901.

On the other hand, the refrigerant flowing through the injection circuit 912 is depressurized by the expansion mechanism 911 (point 9 in FIG. 9) and heat exchanged by the internal heat exchanger 905 (point 10 in FIG. 9) as described above. The gas-liquid two-phase refrigerant (injection refrigerant) that has undergone heat exchange in the internal heat exchanger 905 flows from the injection pipe of the compressor 901 in the gas-liquid two-phase state.
The compression operation in the compressor 901 is the same as that during the heating operation.

When the injection operation is not performed, the opening degree of the expansion mechanism 911 is fully closed to prevent the refrigerant from flowing into the injection pipe of the compressor 901, as in the heating operation.

Further, in the above example, the heat exchanger 902 is described as a heat exchanger such as a plate heat exchanger that exchanges heat between the refrigerant and the water circulating in the water circuit 913. The heat exchanger 902 is not limited to this, and may be a heat exchanger that exchanges heat between the refrigerant and air.
Further, the water circuit 913 may not be a circuit in which water circulates, but a circuit in which another fluid circulates.

In the above example, the heat exchanger 907 has the first portion 907a and the second portion 907b, but it is conceivable that the heat exchanger 902 has two portions instead of or in addition to it. When the heat exchanger 902 is for exchanging heat between the refrigerant and the air, the two parts may each have a fan, and these fans may be driven by separate motors. ..

The configuration in which the heat exchanger 902 or the heat exchanger 907 has two parts has been described above. However, instead of or in addition to this, the compressor 901 has a first part (first compression mechanism) and a second part (first part). It is also conceivable to adopt a configuration having two compression mechanisms). In that case, when the load of the heat pump device 900 is relatively large, both the first portion and the second portion perform a compression operation, and when the load of the heat pump device 900 is relatively small, one of the first portion and the second portion. Only, for example, only the first part is controlled to perform the compression operation.

In such a configuration, the first and second parts of the compressor 901 are provided with separate motors for driving them. For example, the first motor 41 and the second motor 42 described in the first or second embodiment are used to drive the first portion and the second portion, respectively.

The case where at least one of the

heat exchangers

902 and 907 has two parts and two fans are provided for at least one of the

heat exchangers

902 and 907 has been described above. A configuration having a portion of is also conceivable. Generally speaking, at least one of the

heat exchangers

902 and 907 may have a plurality of parts, a fan is provided corresponding to each part, and a motor is provided corresponding to each fan. Possible configurations. In such a case, it is possible to drive the plurality of

motors

41 and 42 with one inverter 4 by using the motor drive devices 100 and 200 described in the first or second embodiment.

Moreover, although the case where the compressor 901 has two parts has been described, a configuration in which the compressor 901 has three or more parts is also conceivable. Generally speaking, the compressor 901 may have a plurality of parts, and a configuration in which a motor is provided corresponding to each part is conceivable. In such a case, it is possible to drive the plurality of

motors

As described above, according to the third embodiment, when there are a plurality of

motors

41 and 42 for driving the compressor 901 or the

fans

910a and 910b, a plurality of

motors

41 and 42 are used by using one inverter 4. Since it is possible to drive the 42, it is possible to reduce the cost and size and weight. Further, by increasing the size of the

heat exchangers

902 and 907 by the amount of miniaturization, the heat exchange efficiency is further increased, and it is possible to improve the efficiency.

Further, since it is possible to adjust the number of motors to be driven by operating the connection switching unit 8, for example, when performing light load operation, only the first motor 41 is operated and overload is performed. When operating, by operating two motors, the first motor 41 and the second motor 42, it is possible to operate only the minimum necessary number of motors, which can contribute to higher efficiency. ..

When the motor drive device 100 or 200 described in the first or second embodiment is applied to the drive motor of the compressor 901, there is no risk of step-out, and therefore a stable refrigerant compression operation is continued. You can Further, since vibration due to current pulsation can be suppressed, not only noise can be reduced, but also damage due to vibration of the piping or the like constituting the main refrigerant circuit 908 can be suppressed.

Furthermore, when the motor drive device 100, 200 described in the first or second embodiment is applied to the drive motor for the

fans

910a, 910b, there is no risk of step-out, so stable heat exchange is continued. be able to. Further, not only vibration due to current pulsation can be suppressed, but also generation of a difference sound due to a speed difference between the two

fans

910a and 910b can be prevented, so that noise can be reduced.

The first to third embodiments described above are merely examples, and it is possible to combine them with other publicly known techniques, and it is possible to make changes such as omitting a part.

As described above, the motor drive devices 100 and 200 according to the first and second embodiments can be applied to, for example, the heat pump device 900 according to the third embodiment, but a plurality of permanent magnets are synchronized. It can be applied to any application as long as the motor is driven at the same rotation speed.

As described above, according to the motor drive devices 100 and 200 described in the first and second embodiments, it is possible to suppress the current imbalance between the

motors

41 and 42 that are connected in parallel. The drive reliability of the

motors

41 and 42 can be improved.

Since the control units 10 and 21 change the phase of the three-phase AC voltage output from the inverter 4, it is possible to easily suppress the current imbalance between the

motors

41 and 42 that are connected in parallel.
Here, since the control units 10 and 21 only have to correct the lead phase angle in the applied voltage phase for calculating the voltage command value used to generate the PWM signal output to the inverter 4, the control target is easily controlled. The current value of the motor current flowing through the motor can be reduced.

By using a wide bandgap semiconductor for each of the plurality of switching elements that make up the inverter 4, low loss and high speed switching can be realized.

When the control unit 10 differs between the current value of the motor current of the first motor 41 and the current value of the motor current of the second motor 42, the current value of the motor current flowing through the motor to be controlled in the inverter 4 becomes smaller. By thus applying the PWM signal to the inverter 4, the first motor 41 and the second motor 42 can be driven so as to have the same motor constant.

When the difference between the current value of the motor current of the first motor 41 and the current value of the motor current of the second motor 42 exceeds a predetermined range, the control unit 21 causes the inverter 4 to flow to the control target motor. By giving a PWM signal to the inverter 4 so that the current value of the motor current becomes small, it is possible to prevent the controlled motor from being frequently switched between the first motor 41 and the second motor 42. ..

The first motor 41 and the second motor 41 and the second motor 41 are provided with a connection switching unit 8 for switching the connection state between at least one motor of the first motor 41 and the second motor 42 and the inverter 4 between connection and disconnection. The number of motors to be driven can be changed according to the load state of the motor 42.

By configuring the connection switching unit 8 with a wide band gap semiconductor, low loss and high speed switching can be realized.

The connection switching unit 8 is composed of an electromagnetic contactor, so that low cost can be realized.

By applying the motor drive device 100 or 200 according to the first or second embodiment to a refrigeration cycle application device, it is possible to improve drive reliability of motors connected in parallel in a heat pump, an air conditioner, or the like.

100, 200 motor drive device, 1 AC power supply, 2 rectifier, 3 smoothing part, 4 inverter, 5 inverter current detection part, 6 motor current detection part, 7 input voltage detection part, 8 connection switching part, 9 switching part, 10, 21 control unit, 11 operation command unit, 12 subtraction unit, 13m, 13l coordinate conversion unit, 14m, 14l speed estimation unit, 15m, 15l integration unit, 16 motor control unit, 17 pulsation compensation control unit, 18 coordinate conversion unit, 19 PWM signal generation unit, 20, 22 advance angle correction unit, 41 first motor, 42 second motor, 900 heat pump device, 901 compressor, 902 heat exchanger, 903 expansion mechanism, 904 receiver, 905 internal heat exchanger, 906 Expansion mechanism, 907 heat exchanger, 907a 1st part, 907b 2nd part, 908 main rectifier circuit, 909 four-way valve, 910a, 910b fan.

Claims

An inverter that is connected to a first motor and a second motor having permanent magnets on a rotor and drives the first motor and the second motor;
A current detection unit for detecting a first motor current, which is a motor current flowing through the first motor, and a second motor current, which is a motor current flowing through the second motor, is provided.
The inverter includes the first motor and the second motor so that a current value of a motor current flowing through a control target motor, which is a motor having a larger current value among the first motor and the second motor, becomes smaller. A motor drive device for driving a motor.
Further comprising a control unit for controlling the inverter,
The inverter drives the first motor and the second motor by applying a three-phase AC voltage to the first motor and the second motor,
The control unit controls the inverter so that the current value of the motor current flowing through the control target motor is reduced by changing the phase of the three-phase AC voltage. Motor drive device.
The inverter generates the three-phase AC voltage by switching the DC voltage with a plurality of switching elements.
The control unit controls the inverter by giving a PWM (Pulse Width Modulation) signal for turning on or off the plurality of switching elements to the inverter,
The control unit corrects the lead phase angle in the applied voltage phase for calculating the voltage command value used to generate the PWM signal, so that the current value of the motor current flowing through the control target motor becomes small. The motor drive device according to claim 2, wherein:
The motor drive device according to claim 3, wherein the switching element is composed of a wide bandgap semiconductor.
When the current value of the first motor current and the current value of the second motor current are different, the control unit causes the inverter to reduce the current value of the motor current flowing to the control target motor. The motor drive device according to any one of claims 2 to 4, wherein the first motor and the second motor are driven.
When the difference between the current value of the first motor current and the current value of the second motor current exceeds a predetermined range, the control unit causes the inverter to control the motor current flowing to the control target motor. The motor drive device according to any one of claims 2 to 4, wherein the first motor and the second motor are driven so that a current value becomes small.
The connection switching part which switches the connection state of at least 1 motor of the said 1st motor and the said 2nd motor, and the said inverter between connection and disconnection is further provided. The motor drive device according to claim 1.
The motor drive device according to claim 7, wherein the connection switching unit is made of a wide bandgap semiconductor.
The motor drive device according to claim 7, wherein the connection switching unit is composed of an electromagnetic contactor.
A refrigeration cycle application device comprising the motor drive device according to any one of claims 1 to 9.
The heat exchanger of the refrigeration cycle application device has a first portion and a second portion,
The first motor is provided corresponding to the first portion,
The second motor is provided corresponding to the second portion,
Depending on the load of the refrigeration cycle application device, the part of the first part and the second part that performs the heat exchange operation is switched,
The first motor is driven by the inverter when the first portion performs a heat exchange operation,
The refrigeration cycle application device according to claim 10, wherein the second motor is driven by the inverter when the second portion performs a heat exchange operation.
The first motor is used to rotate a first fan provided corresponding to the first portion,
The refrigeration cycle application device according to claim 11, wherein the second motor is used to rotate a second fan provided corresponding to the second portion.
The compressor of the refrigeration cycle application device has a first part and a second part,
The first motor is provided corresponding to the first portion,
The second motor is provided corresponding to the second portion,
Depending on the load of the refrigeration cycle application device, a portion of the first portion and the second portion that performs a compression operation is switched,
The first motor is driven by the inverter when the first portion performs a compression operation,
The refrigeration cycle application device according to claim 10, wherein the second motor is driven by the inverter when the second portion performs a compression operation.