WO2021117090A1 - Motor drive device and air-conditioning device - Google Patents

Abstract

This motor drive device (200) comprises: a bridge diode (10) that rectifies an alternating current power source (9); capacitors (12a, 12b) that store electrical charges output from the bridge diode (10); a booster circuit (11) that charges the capacitors (12a, 12b), thereby boosting a voltage output from the bridge diode (10); and an inverter circuit (13) that uses the voltage supplied from the capacitors (12a, 12b) to drive a motor. When N is a number greater than 1, and when a first capacity is the capacity of the capacitors (12a, 12b) when the voltage output from the bridge diode (10) is boosted by a factor of N by the booster circuit (11), and a second capacity is the capacity of the capacitors (12a, 12b) without the booster circuit (11), the first capacity is smaller than the second capacity and at least 1/Nth of the second capacity.

Description

Motor drive and air conditioner

The present invention relates to a motor drive device for driving a motor and an air conditioner.

The outdoor unit of the air conditioner is equipped with a motor drive device that drives the motor. The motor drive device described in Patent Document 1 uses a converter circuit that rectifies an AC power supply, a booster circuit that boosts the voltage output from the converter circuit by using the function of a capacitor, and a boosted voltage to drive the motor. It is equipped with an inverter circuit.

JP-A-2019-88047

However, in the technique of Patent Document 1, even when the booster circuit is used, the electric charge is stored by using the capacitor having the same capacity as when the booster circuit is not used. Therefore, the capacitor which stores the electric charge at the time of boosting is used. It could not be miniaturized.

The present invention has been made in view of the above, and an object of the present invention is to obtain a motor drive device capable of miniaturizing a capacitor that stores electric charges during boosting while using a boosting circuit.

In order to solve the above-mentioned problems and achieve the object, the motor drive device of the present invention has a converter circuit that rectifies an AC power supply, a first capacitor that stores the charge output from the converter circuit, and a first capacitor. A booster circuit that boosts the voltage output from the converter circuit by charging the capacitor, and an inverter circuit that drives the motor using the voltage supplied from the first capacitor are provided. When N is a number larger than 1, the capacity of the first capacitor when the booster circuit boosts the voltage output from the converter circuit by N times is the first capacity, and when there is no booster circuit, the capacity of the second capacitor Assuming that the capacity is the second capacity, the first capacity is smaller than the second capacity and is 1/N or more of the second capacity.

The motor drive device according to the present invention has an effect that the capacitor that stores electric charge at the time of boosting can be miniaturized while using the boosting circuit.

The figure which shows the structure of the air conditioner which concerns on embodiment The figure which shows the structure of the motor drive device which concerns on embodiment The figure which shows the structure of the motor drive device which does not have a booster circuit. The figure which shows the schematic waveform of the capacitor output voltage of the motor drive device which does not have a booster circuit. The figure which shows the schematic waveform of the capacitor output voltage of the motor drive device which concerns on embodiment.

Hereinafter, the motor drive device and the air conditioner according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment.
FIG. 1 is a diagram showing a configuration of an air conditioner according to an embodiment. The air conditioner 100 includes an indoor unit 1, an outdoor unit 4, and a display device 8. The air conditioner 100 is a separate type air conditioner in which the indoor unit 1 and the outdoor unit 4 are separated.

An indoor control device 2 and an indoor fan 3 are provided in the indoor unit 1. An outdoor fan 5, an outdoor control device 6, a compressor 7, and a motor 14 are provided in the outdoor unit 4. The indoor control device 2 is connected to the outdoor control device 6 and the display device 8.

The indoor control device 2 controls the indoor unit 1, and the indoor fan 3 circulates the indoor air. The outdoor control device 6 controls the outdoor unit 4, and the outdoor fan 5 supplies air to the outdoor unit 4. The compressor 7 compresses the refrigerant to change the temperature of the air.

The display device 8 displays information such as the operation of the air conditioner 100. The display device 8 is visible to the user of the air conditioner 100. The outdoor unit 4 includes a motor 14 for operating the compressor 7, and the outdoor control device 6 includes a motor drive device 200 for driving the motor 14.

FIG. 2 is a diagram showing a configuration of a motor drive device according to an embodiment. The motor drive device 200 includes a bridge diode 10, a booster circuit 11, a charge storage unit 12, and an inverter circuit 13. The motor drive device 200 is configured by arranging a bridge diode 10, a booster circuit 11, a charge storage unit 12, and an inverter circuit 13 on a substrate.

The bridge diode 10 is connected to the AC power supply 9 and the charge storage unit 12, and the charge storage unit 12 is connected to the booster circuit 11 and the inverter circuit 13. Further, the inverter circuit 13 is connected to the booster circuit 11, the charge storage unit 12, and the motor 14.

The bridge diode 10 has the function of a converter circuit, and rectifies the three-phase AC voltage applied from the AC power supply 9 and converts it into a DC voltage. In the bridge diode 10, six diodes are bridge-connected. When the AC voltage applied from the AC power supply 9 is single-phase, four diodes are bridge-connected to the bridge diode 10.

The booster circuit 11 is a circuit that boosts the voltage output from the bridge diode 10 to, for example, twice the voltage. That is, an example of the booster circuit 11 is a voltage doubler circuit. The booster circuit 11 may boost the voltage output from the bridge diode 10 to a voltage that is a multiple other than twice, such as 1.5 times or 4 times. That is, the booster circuit 11 may boost the voltage several times as long as it boosts the voltage to a voltage larger than the voltage output from the bridge diode 10.

The booster circuit 11 includes a reactor 11a, a switching element 11b which is a switching element on the positive electrode side, a switching element 11c which is a switching element on the negative electrode side, a diode 11d, and a diode 11e. The switching element 11b is the first switching element, and the switching element 11c is the second switching element. Further, the diode 11d is the first diode, and the diode 11e is the second diode. The booster circuit 11 does not have to have the reactor 11a.

The reactor 11a is connected to the positive electrode side output of the bridge diode 10. The anode side of the diode 11d is connected to the reactor 11a via the connection point 21 on the positive electrode side. Further, the diode 11d is connected to the charge storage unit 12 via the connection point 23 on the positive electrode side on the cathode side.

The cathode side of the diode 11e is connected to the negative electrode side output of the bridge diode 10 via the connection point 22 on the negative electrode side. Further, the anode side of the diode 11e is connected to the charge storage unit 12 via the connection point 24 on the negative electrode side. The connection point 21 is the first connection point, and the connection point 22 is the second connection point.

A switching element 11b and a switching element 11c are connected in series between the connection point 21 and the connection point 22. Specifically, the switching element 11b on the positive electrode side is connected to the connection point 21 and the connection point 25, and the switching element 11c on the negative electrode side is connected to the connection point 22 and the connection point 25. That is, the switching element 11b is connected to the anode side of the diode 11d via the connection point 21, and the switching element 11c is connected to the cathode side of the diode 11e via the connection point 22.

The charge storage unit 12 stores the charge sent from the booster circuit 11. The charge storage unit 12 has a capacitor 12a which is a smoothing electrolytic capacitor on the positive electrode side and a capacitor 12b which is a smoothing electrolytic capacitor on the negative electrode side.

In the charge storage unit 12, the capacitor 12a and the capacitor 12b are connected in series between the connection point 23 and the connection point 24. Specifically, the capacitor 12a on the positive electrode side is connected to the connection point 23 and the connection point 26, and the capacitor 12b on the negative electrode side is connected to the connection point 24 and the connection point 26. The connection point 23 is connected to the cathode side of the diode 11d and the inverter circuit 13, and the connection point 24 is connected to the anode side of the diode 11e and the inverter circuit 13. That is, the capacitor 12a is connected to the positive electrode side output of the booster circuit 11 via the connection point 23, and the capacitor 12b is connected to the negative electrode side output of the booster circuit 11 via the connection point 24. The connection point 26 is connected to the connection point 25.

In the motor drive device 200, the charge output from the booster circuit 11 is stored in the capacitors 12a and 12b, and the stored charge is supplied to the inverter circuit 13, so that the voltage output from the bridge diode 10 is boosted. It is supplied to the inverter circuit 13 in this state. In this case, the diodes 11d and 11e are held by the capacitors 12a and 12b so that the electric charge stored in the capacitors 12a and 12b does not return to the booster circuit 11.

The inverter circuit 13 converts the DC voltage smoothed by the charge storage unit 12 into an AC voltage and applies it to the motor 14. In this way, power is supplied to the motor 14 from the charge storage unit 12 via the inverter circuit 13.

The inverter circuit 13 is a circuit in which a plurality of transistors and diodes are connected in parallel and made into a three-phase bridge. Specifically, the inverter circuit 13 has three legs, and each leg is connected in parallel between the generatrix on the positive electrode side and the generatrix on the negative electrode side. The first leg is a circuit unit in which a U-phase upper arm switching element and a U-phase lower arm switching are connected in series. The second leg is a circuit unit in which a V-phase upper arm switching element and a V-phase lower arm switching are connected in series. The third leg is a circuit unit in which a W-phase upper arm switching element and a W-phase lower arm switching are connected in series. The bus on the positive electrode side of the inverter circuit 13 is connected to the connection point 23, and the bus on the negative electrode side of the inverter circuit 13 is connected to the connection point 24.

Although the AC power supply 9 is a three-phase power supply in FIG. 2, the AC power supply 9 may be a single-phase power supply. When the AC power supply 9 is a single-phase power supply, the bridge diode 10 which is a converter circuit is configured to match the single-phase power supply. An example of the motor 14 is a three-phase motor.

Next, the operation of the air conditioner 100 will be described. In the air conditioner 100, the outdoor control device 6 of the outdoor unit 4 drives the outdoor fan 5 and the compressor 7, and the indoor control device 2 receives the signal sent from the outdoor control device 6 and receives the signal sent from the outdoor control device 6, and the indoor fan 3 To harmonize the air in the room.

Further, in the outdoor control device 6, the bridge diode 10 full-wave rectifies the AC power supply 9, and the booster circuit 11 boosts the voltage. Then, the charge storage unit 12 smoothes the full-wave rectified and boosted voltage. Further, in the outdoor control device 6, the inverter circuit 13 drives the motor 14 by converting the boosted and smoothed DC voltage into an AC voltage and applying it to the motor 14.

FIG. 3 is a diagram showing a configuration of a motor drive device not provided with a booster circuit. As shown in FIG. 3, the motor drive device 201 includes a bridge diode 10, a charge storage unit 12X, and an inverter circuit 13. That is, the motor drive device 201 does not include the booster circuit 11 as compared with the motor drive device 200.

In the motor drive device 201, the bridge diode 10 is connected to the AC power supply 9, the charge storage unit 12X and the inverter circuit 13, and the inverter circuit 13 is connected to the charge storage unit 12X and the motor 14.

The positive electrode side output of the bridge diode 10 is connected to the inverter circuit 13 via the positive electrode side connection point 31. Further, the output on the negative electrode side of the bridge diode 10 is connected to the inverter circuit 13 via the connection point 32 on the negative electrode side.

The charge storage unit 12X stores the charge output from the bridge diode 10. The charge storage unit 12X has a capacitor 12c which is a smoothing electrolytic capacitor on the positive electrode side and a capacitor 12d which is a smoothing electrolytic capacitor on the negative electrode side.

In the charge storage unit 12X, the capacitor 12c and the capacitor 12d are connected in series between the connection point 31 and the connection point 32. Specifically, the positive electrode side capacitor 12c is connected to the connection point 31 and the negative electrode side capacitor 12d, and the negative electrode side capacitor 12d is connected to the connection point 32 and the positive electrode side capacitor 12c. That is, the capacitor 12c is connected to the positive electrode side output of the bridge diode 10 and the positive electrode side bus of the inverter circuit 13 via the connection point 31. The capacitor 12d is connected to the negative electrode side output of the bridge diode 10 and the negative electrode side bus wire of the inverter circuit 13 via the connection point 32.

The capacitances of the capacitors 12c and 12d are the sizes required when the booster circuit 11 is not arranged. Conventionally, even when the booster circuit is arranged in the motor drive device 201, the capacitors 12c and 12d having a large capacity have been adopted as they are. In the present embodiment, while arranging the booster circuit 11 in the motor drive device 200, the first capacitance of the capacitors 12a and 12b, which are the first capacitors, is used as the second capacitance of the capacitors 12c and 12d, which are the second capacitors. The capacity is smaller than the capacity. For example, when the booster circuit 11 boosts the voltage output from the bridge diode 10 to twice the voltage, the capacitance of the capacitors 12a and 12b is half the capacitance of the capacitors 12c and 12d.

Next, the voltage smoothing process by the capacitors 12a and 12b in the charge storage unit 12 of the motor drive device 200 and the voltage smoothing process by the capacitors 12c and 12d in the charge storage unit 12X of the motor drive device 201 will be described. FIG. 4 is a diagram showing a schematic waveform of a capacitor output voltage of a motor drive device not provided with a booster circuit. FIG. 5 is a diagram showing a schematic waveform of a capacitor output voltage of the motor drive device according to the embodiment.

In FIG. 4, the voltage waveform 52 shown by the broken line is the voltage waveform obtained by full-wave rectification, and the voltage waveform 42 shown by the solid line is the voltage waveform (capacitor output voltage) after being smoothed by the capacitors 12c and 12d. Further, in FIG. 5, the voltage waveform 51 shown by the broken line is the voltage waveform obtained by full-wave rectification, and the voltage waveform 41 shown by the solid line is the voltage waveform after being smoothed by the capacitors 12c and 12d. Here, in the motor drive devices 200 and 201, the case where the output of the AC power supply 9 has a peak voltage of 100 V and the input voltage to the inverter circuit 13 is 80 V will be described.

In the motor drive device 201 that does not have a booster circuit, the voltage smoothed by the charge storage unit 12X becomes the voltage waveform 42 shown in FIG. 4, in order to maintain 80V or avoid dropping to 80V or less. In order to do so, the ripple needs to be small.

In the motor drive device 200 having the booster circuit 11, the output voltage of the AC power supply 9 via the bridge diode 10 is converted into a voltage with a peak voltage of 200 V by the booster circuit 11. The voltage smoothed by the charge storage unit 12 of the motor drive device 200 becomes the voltage waveform 41 shown in FIG. 5, and 80 V can be obtained as the input voltage to the inverter circuit 13 even with a large ripple.

The capacity of the capacitor can be calculated by the following formula (1). In the formula (1), C is the capacity of the capacitor, P is the output power of the capacitor, t is the discharge time of the capacitor, V0 is the charge voltage to the capacitor, and V1 is the discharge voltage of the capacitor.

Assuming that the inverter circuit 13 and the motor 14 are the same in the motor drive device 201 having no booster circuit and the motor drive device 200 having the booster circuit 11, the capacitors 12a and 12b and the capacitors 12c and 12d output the power. The power P, the discharge time t, and the discharge voltage V1 are the same. However, the charging voltage V0 of the capacitors 12a and 12b when the booster circuit 11 is provided is twice the charging voltage V0 of the capacitors 12c and 12d when the booster circuit 11 is not provided. The charging voltage V0 of the capacitors 12a and 12b is the first charging voltage, and the charging voltage V0 of the capacitors 12c and 12d is the second charging voltage.

From equation (1), when the output power P, the discharge time t, and the discharge voltage V1 are the same and the charging voltage V0 is doubled, the capacity of the electrolytic capacitor is reduced to half. As a result, in the motor drive device 200 having the booster circuit 11, the capacitance of the capacitors 12a and 12b can be made smaller than the capacitance of the capacitors 12c and 12d of the motor drive device 201 having no booster circuit 11.

As described above, in the present embodiment, in the motor drive device 200, the booster circuit 11 is arranged and the capacities of the capacitors 12a and 12b are smaller than those of the capacitors 12c and 12d when the booster circuit 11 is not arranged. For example, when the booster circuit 11 boosts the voltage output from the bridge diode 10 to a voltage N times that of N, the capacitance of the capacitors 12a and 12b is 1/1N of the capacitance of the capacitors 12c and 12d. I will leave it as. As a result, the capacitances of the capacitors 12a and 12b can be reduced according to the magnitude of the boosting by the booster circuit 11. The capacitance of the capacitors 12a and 12b may be any capacitance as long as it is 1/N or more of the capacitance of the capacitors 12c and 12d and smaller than the capacitance of the capacitors 12c and 12d. When the capacitances of the capacitors 12a and 12b are C1 and the capacitances of the capacitors 12c and 12d are C2, an example of the capacitances of the capacitors 12a and 12b is a capacitance satisfying (1 / N) × C2 ≦ C1 <C2.

Since the outer shape of the capacitor increases in proportion to the capacitance, it is possible to reduce the size of the capacitor by reducing the capacitance of the capacitor. Therefore, the external dimensions of the capacitors 12a and 12b can be made smaller than the external dimensions of the capacitors 12c and 12d.

Conventionally, even when the booster circuit is arranged in the motor drive device 201, the capacitors 12c and 12d having a large capacity are used as they are, so that the outer shapes of the capacitors 12c and 12d remain large.

The peak voltage value of the AC power supply 9 and the input voltage value to the inverter circuit 13 described in the present embodiment are examples, and any other value may be applied to the motor drive device 200. ..

In the present embodiment, the case where the capacitors 12a and 12b are electrolytic capacitors has been described, but the capacitors 12a and 12b may be film capacitors instead of electrolytic capacitors. In the present embodiment, since the capacitors 12a and 12b can have a small capacity, a necessary capacity can be secured even when the capacitors 12a and 12b are used as a film capacitor or the like.

Further, the motor drive device 200 of the present embodiment is not used to switch the switching elements 11b and 11c at high speed depending on the type of load such as the motor 14. Therefore, in the motor drive device 200, heat generation and noise of the switching elements 11b and 11c do not increase depending on the type of load. Therefore, the life of the switching elements 11b and 11c is not shortened.

As described above, in the embodiment, the capacitance of the capacitors 12a and 12b when the booster circuit 11 doubles the voltage output from the bridge diode 10 with N as a number larger than 1 is the case where there is no booster circuit. It is half of the capacity. Therefore, in the motor drive device 200, the capacitors 12a and 12b that store electric charges at the time of boosting can be miniaturized while using the booster circuit 11.

Further, since small-capacity capacitors 12a and 12b can be used, not only smoothing electrolytic capacitors but also film capacitors and the like can be applied.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 indoor unit, 2 indoor control device, 3 indoor fan, 4 outdoor unit, 5 outdoor fan, 6 outdoor control device, 7 compressor, 8 display device, 9 AC power supply, 10 bridge diode, 11 booster circuit, 11a reactor, 11b , 11c switching element, 11d, 11e diode, 12, 12X charge storage unit, 12a, 12b, 12c, 12d capacitor, 13 inverter circuit, 14 motor, 21-26, 31, 32 connection point, 41, 42, 51, 52 Voltage waveform, 100 air conditioner, 200, 201 motor drive.

Claims (7)

A converter circuit that rectifies AC power and
A first capacitor that stores the electric charge output from the converter circuit,
A booster circuit that boosts the voltage output from the converter circuit by charging the first capacitor, and a booster circuit.
An inverter circuit that drives a motor using the voltage supplied from the first capacitor,
With
When N is a number larger than 1, the capacity of the first capacitor when the booster circuit boosts the voltage output from the converter circuit by N times is set as the first capacity, and when there is no booster circuit, the first capacity is the first. Assuming that the capacity of the second capacitor is the second capacity,
A motor drive device in which the first capacity is smaller than the second capacity and is at least 1/N of the second capacity. The first capacitor is an electrolytic capacitor.
The motor drive device according to claim 1. The first capacitor is a film capacitor.
The motor drive device according to claim 1. The booster circuit is a voltage doubler circuit that doubles the voltage output from the converter circuit.
The motor drive device according to any one of claims 1 to 3. The booster circuit
A first diode having an anode connected to the positive electrode output side of the converter circuit,
A second diode whose cathode is connected to the negative electrode output side of the converter circuit,
A first switching element connected to the positive electrode output side via a first connection point connecting the anode of the first diode and the positive electrode output side, and
A second switching element connected to the negative electrode output side via a second connection point connecting the cathode of the second diode and the negative electrode output side, and
Have,
The motor drive device according to any one of claims 1 to 4. The booster circuit
A reactor is connected between the positive electrode output side of the converter circuit and the first connection point.
The motor drive device according to claim 5. The motor drive device according to any one of claims 1 to 6.
A compressor having a motor driven by the motor drive device, and
Air conditioner equipped with.

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