阅读说明：本技术 电力转换装置 (Power conversion device ) 是由 黑木涉 于 2020-09-04 设计创作，主要内容包括：电力转换装置(10)具有：转换器(12),其具有与三相交流电源的各相对应的输入端子(12I)(12R、12S、12T)以及开关元件(36),将三相交流电源的交流电压转换为直流电压；以及电容器(14),其使由转换器(12)转换后的直流电压平滑化。在转换器(12)的三相中的任意两相所对应的两个输入端子(12I)上连接有单相交流电源(24)或直流电源,以将未连接单相交流电源(24)或直流电源的相所对应的一个输入端子(12I)与电容器(14)的一端相连的方式连接有无源元件。(A power conversion device (10) is provided with: a converter (12) having input terminals (12I) (12R, 12S, 12T) corresponding to the respective three-phase AC power supplies and a switching element (36) and converting an AC voltage of the three-phase AC power supply into a DC voltage; and a capacitor (14) that smoothes the DC voltage converted by the converter (12). A single-phase AC power supply (24) or a DC power supply is connected to two input terminals (12I) corresponding to any two of the three phases of the converter (12), and a passive element is connected so that one input terminal (12I) corresponding to a phase to which the single-phase AC power supply (24) or the DC power supply is not connected is connected to one end of the capacitor (14).)

1. A power conversion device has:

a converter having input terminals and switching elements corresponding to respective three-phase ac power supplies, the converter converting ac voltages of the three-phase ac power supplies into dc voltages; and

a capacitor for smoothing the DC voltage converted by the converter,

the power conversion device is characterized in that:

a single-phase ac power supply or a dc power supply is connected to two input terminals corresponding to any two of the three phases of the converter,

a passive element is connected to one of the input terminals corresponding to the phases to which the single-phase ac power supply or the dc power supply is not connected and one end of the capacitor.

2. The power conversion device according to claim 1, comprising:

a voltage detection unit that detects a voltage of the capacitor; and

a control unit that controls the switching elements corresponding to the respective converters,

when the voltage of the capacitor exceeds a threshold value, the control unit turns on the switching element corresponding to a phase of the input terminal to which the single-phase ac power supply or the dc power supply is not connected, and discharges the charge stored in the capacitor.

3. The power conversion apparatus according to claim 2,

reactors are connected to the power supply side of at least one of the three input terminals of the converter,

the passive element is a discharge resistor connected to connect the input terminal side of the reactor or the power supply side of the reactor to one end of the capacitor.

4. The power conversion apparatus according to claim 3,

the control unit controls the switching elements corresponding to the two phases to which the single-phase ac power supply or the dc power supply is connected, to perform power regeneration, while turning on the switching elements corresponding to the phases to which the input terminals of the single-phase ac power supply or the dc power supply are not connected, thereby discharging the electric charges accumulated in the capacitor.

5. The power conversion apparatus according to claim 2,

a reactor is connected to a power supply side of at least one of the three input terminals of the converter,

the passive element is a capacitor for power storage, and is connected so as to connect a power supply side of the reactor and one end of the capacitor.

6. The power conversion apparatus according to claim 5,

the control unit prohibits control of the switching elements corresponding to the two phases to which the single-phase ac power supply or the dc power supply is connected, while discharging the electric charge stored in the capacitor and charging the storage capacitor by turning on the switching elements corresponding to the phases to which the input terminal of the single-phase ac power supply or the dc power supply is not connected.

Technical Field

The present invention relates to a power conversion device that converts an ac voltage supplied from an ac power supply into a dc voltage.

Background

In japanese patent laid-open publication No. 2012-165509, in a power conversion device that converts three-phase ac voltage into dc voltage, an inrush current prevention circuit is implemented by a single-phase power supply.

Disclosure of Invention

However, in a power conversion device capable of converting a three-phase ac voltage into a dc voltage, when a single-phase power supply is used as a power supply, an idle circuit (hereinafter referred to as an idle circuit) is generated, and there is a problem that the circuit is not used and is wasted.

Therefore, an object of the present invention is to provide a power conversion device capable of effectively utilizing an idle circuit.

An aspect of the present invention is a power conversion device including: a converter having input terminals and switching elements corresponding to respective three-phase ac power supplies, the converter converting ac voltages of the three-phase ac power supplies into dc voltages; and a capacitor that smoothes the dc voltage converted by the converter. A single-phase ac power supply or a dc power supply is connected to two input terminals corresponding to any two of three phases of the converter, and a passive element is connected to connect one of the input terminals corresponding to a phase to which the single-phase ac power supply or the dc power supply is not connected to one end of the capacitor.

According to the present invention, the idle circuit can be effectively utilized.

The above objects, features and advantages will be readily apparent from the following description of the embodiments with reference to the accompanying drawings.

Drawings

Fig. 1 is a circuit configuration diagram of a power conversion device in the embodiment.

Fig. 2 is a circuit configuration diagram of a power conversion device in modification 1.

Fig. 3 is a circuit configuration diagram of a power conversion device in modification 2.

Detailed Description

Hereinafter, a power converter according to the present invention will be described in detail with reference to the accompanying drawings by referring to preferred embodiments.

[ embodiment ]

Fig. 1 is a circuit configuration diagram of a power conversion device 10 in the embodiment. The power conversion device 10 includes a converter 12, a capacitor 14, a voltage detection unit 20a, and a control unit 20. The power conversion device 10 converts electric power supplied from an ac power supply into dc power, and supplies the electric power to the converter 16 or regenerates regenerative energy from the ac power supply. The converter 16 converts dc power into ac power and supplies the ac power to the motor 22, or converts regenerative energy generated when the motor 22 decelerates into dc power and supplies the dc power to the power conversion device 10.

Converter 12 has input terminals 12R, 12S, and 12T corresponding to respective phases (R phase, S phase, and T phase) of the three-phase ac power supply. When the input terminals 12R, 12S, and 12T are collectively referred to as an input terminal 12I. Reactors 18(18R, 18S, 18T) are connected to the power supply side of three input terminals 12R, 12S, 12T of converter 12, respectively.

The switch 26 is connected to the reactor 18(18R, 18S, 18T). When the input terminals 26R, 26S, and 26T of the switch 26 are connected to the three-phase ac power supply, the switch 26 can turn on or off the connection between each phase of the three-phase ac power supply and the reactors 18R, 18S, and 18T. In fig. 1, a state in which the switch 26 is turned on is shown.

In fig. 1, since the single-phase ac power supply 24 is connected only to the input terminals 26S and 26T, the switch 26 can turn on or off the connection between the single-phase ac power supply 24 and the reactors 18S and 18T. In fig. 1, a single-phase ac power supply 24 is connected to input terminals 12S, 12T of converter 12 corresponding to two phases (S-phase and T-phase) via a switch 26 and a reactor 18(18S, 18T).

Converter 12 includes power element units 30R, 30S, and 30T corresponding to the phases (R phase, S phase, and T phase) of the three-phase ac power supply.

The power element unit 30R corresponding to R includes an upper arm side diode 34Ru, a lower arm side diode 34Rd, an upper arm side switching element (semiconductor switching element) 36Ru, and a lower arm side switching element 36 Rd.

The power element section 30S corresponding to S includes an upper arm side diode 34Su, a lower arm side diode 34Sd, an upper arm side switching element 36Su, and a lower arm side switching element 36 Sd.

The power element unit 30T corresponding to T includes an upper arm side diode 34Tu, a lower arm side diode 34Td, an upper arm side switching element 36Tu, and a lower arm side switching element 36 Td.

The symbol 34 is used when collectively referring to the diodes 34Ru, 34Rd, 34Su, 34Sd, 34Tu, 34 Td. Note that, when the entire upper arm side diode is described, reference numeral 34u is used, and when the entire lower arm side diode is described, reference numeral 34d is used.

The symbol 36 is used when the switching elements 36Ru, 36Rd, 36Su, 36Sd, 36Tu, and 36Td are collectively referred to. Note that, when the entire upper arm side switching element is described, reference numeral 36u is used, and when the entire lower arm side switching element is described, reference numeral 36d is used. For example, an Insulated Gate Bipolar Transistor (IGBT) may be used as the switching element 36, but the invention is not limited thereto. A FET (Field Effect Transistor) may also be used as the switching element 36.

The upper arm side diode 34u and the lower arm side diode 34d are connected in series with each other. The cathode of the diode 34u on the upper arm side is connected to the output line 42u on the positive electrode side. The anode of the diode 34u on the upper arm side is connected to the cathode of the diode 34d on the lower arm side. The anode of the diode 34d on the lower arm side is connected to the output line 42d on the negative side.

The upper arm side switching element 36u and the lower arm side switching element 36d are connected in series with each other. A first terminal of the switching element 36u on the upper arm side is connected to a cathode of the diode 34u on the upper arm side. A second terminal of the upper arm-side switching element 36u is connected to an anode of the upper arm-side diode 34 u. A first terminal of the switching element 36d on the lower arm side is connected to a cathode of the diode 34d on the lower arm side. A second terminal of the lower arm-side switching element 36d is connected to an anode of the lower arm-side diode 34 d. When the switching element 36 is, for example, an IGBT, the first terminal is a collector and the second terminal is an emitter. In the case where the switching element 36 is, for example, an FET, the first terminal is one of the source/drain, and the second terminal is the other of the source/drain.

An input terminal 12R is connected to a node 38R connected to an anode of the upper arm-side diode 34Ru, a second terminal of the upper arm-side switching element 36Ru, a cathode of the lower arm-side diode 34Rd, and a first terminal of the lower arm-side switching element 36 Rd.

An input terminal 12S is connected to a node 38S connected to the anode of the upper arm-side diode 34Su, the second terminal of the upper arm-side switching element 36Su, the cathode of the lower arm-side diode 34Sd, and the first terminal of the lower arm-side switching element 36 Sd.

An input terminal 12T is connected to a node 38T connected to an anode of the upper arm-side diode 34Tu, a second terminal of the upper arm-side switching element 36Tu, a cathode of the lower arm-side diode 34Td, and a first terminal of the lower arm-side switching element 36 Td.

The converter 12 converts an ac voltage of the three-phase ac power supply into a dc voltage by controlling the switching element 36 by the control unit 20. The converter 12 is, for example, a well-known Pulse Width Modulation (PWM) converter, but is not limited thereto.

The capacitor 14 is provided at the rear stage of the converter 12. One end of the capacitor 14 on the positive side is connected to the output line 42 u. One end on the negative side of the capacitor 14 is connected to the output line 42 d. Capacitor 14 smoothes the dc voltage converted and output by converter 12.

The converter 16 is connected to the output lines 42u and 42d, converts the dc voltage smoothed by the capacitor 14 into an ac voltage, and applies the ac voltage to the motor 22 to drive the motor 22.

The voltage detection unit 20a is connected to the output lines 42u and 42d, and detects the voltage of the capacitor 14.

When the single-phase ac power supply 24 is connected to the power conversion device 10 that can convert electric power from the three-phase ac power supply, any one of the power element units 30R, 30S, and 30T is not connected to the single-phase ac power supply 24 and is wasted as an idle circuit. In addition, unlike this, there is a problem that the voltage of the capacitor 14 becomes excessively high due to regenerative energy generated from the motor 22.

Therefore, in the power conversion device 10 of the present embodiment, the discharge resistor 46 as a passive element is connected between the input terminal 12I (12R, 12S, 12T) corresponding to the phase to which the single-phase ac power supply 24 is not connected and any one end of the capacitor 14. The control unit 20 controls the idle circuit to solve the above problem.

In the example shown in fig. 1, the R-phase power element unit 30R corresponding to the input terminal 12R to which the single-phase ac power supply 24 is not connected is an idle circuit. Therefore, the other end of the discharge resistor 46 having one end connected to the input terminal 12R corresponding to the R phase is connected to one end of the capacitor 14 on the negative electrode side via the output line 42 d.

When the voltage of the capacitor 14 detected by the voltage detection unit 20a exceeds a predetermined threshold value, the control unit 20 controls the switching element 36Ru on the upper arm side connected to the input terminal 12R to which the single-phase ac power supply 24 is not connected to be turned on. Thereby, the electric charge accumulated in the capacitor 14 is discharged, and a current flows in the order of the positive electrode of the capacitor 14, the switching element 36Ru, the discharge resistor 46, and the negative electrode of the capacitor 14. As a result, the discharge resistor 46 can consume the surplus power, and therefore, the voltage of the capacitor 14 whose voltage has become excessively high can be reduced, and the idle circuit can be effectively used.

The other end of the discharge resistor 46 having one end connected to the input terminal 12R may be connected to one end of the positive electrode side of the capacitor 14 via the output line 42 u. In this case, the control unit 20 controls the switching element 36Rd on the lower arm side connected to the input terminal 12R of the connection discharge resistor 46 to be turned on. Thus, a current flows in the order of the positive electrode of the capacitor 14, the discharge resistor 46, the switching element 36Rd, and the negative electrode of the capacitor 14. As a result, the discharge resistor 46 consumes the surplus power, the voltage of the capacitor 14 can be reduced, and the idle circuit can be effectively used.

When the control unit 20 performs the above control to cause the discharge resistor 46 to consume the surplus power, the control unit 20 may perform power regeneration for returning the regenerative energy generated from the motor 22 to the power supply side by controlling the 36Su, 36Sd, 36Tu, and 36Td connected to the input terminals 12S and 12T. This makes it possible to effectively use regenerative energy.

Even if the control unit 20 executes control for regenerating the power supply for returning the regenerative energy generated from the motor 22 to the power supply side, the control may be performed such that the discharge resistor 46 consumes the surplus power when the voltage of the capacitor 14 exceeds the threshold value due to the regenerative energy.

As described above, the power conversion device 10 can effectively use the power element unit 30R which is not connected to the single-phase ac power supply 24 and becomes an idle circuit.

Instead of the single-phase ac power supply 24, a dc power supply such as a battery may be connected to the input terminals 12S and 12T via the switch 26 and the reactor 18(18S and 18T). Since the single-phase ac power supply 24 or the dc power supply need only be connected to two input terminals 12I corresponding to any two of the three phases of the converter 12, it may be connected to the input terminals 12R and 12T or the input terminals 12R and 12S. In these cases, the discharge resistor 46 may be connected between the one input terminal 12I to which the single-phase ac power supply 24 or the dc power supply is not connected and one end of the positive side or the negative side of the capacitor 14. When the other end of the discharge resistor 46 is connected to the positive-side end of the capacitor 14, the switching element 36d on the lower arm side corresponding to the phase of the input terminal 12I to which the one end of the discharge resistor 46 is connected is turned on, and the capacitor 14 is discharged. When the other end of discharge resistor 46 is connected to the negative-side one end of capacitor 14, switching element 36u on the upper arm side corresponding to the phase of input terminal 12I to which the one end of discharge resistor 46 is connected is turned on, and capacitor 14 is discharged. Further, the switch 26 and the reactor 18 may be used not for a three-phase ac power supply but for a single-phase ac power supply or a dc power supply. The switch 26 may be directly connected to the input terminals 12R, 12S, and 12T without the reactor 18.

[ modified examples ]

The above embodiment may be modified as follows.

(modification 1)

Fig. 2 is a circuit configuration diagram of the power conversion device 10 in modification 1. Unlike the above-described embodiment, in modification 1, the discharge resistor 46 as a passive element is connected between the output line 42d and the power supply side terminal 50R of the reactor 18R connected to the input terminal 12R to which the single-phase ac power supply 24 is not connected. The operation of the power conversion device 10 in modification 1 is the same as that described in the above embodiment. In modification 1, the power element section 30R as an idle circuit can also be effectively used. In the case of modification 1, the switch 26 may be directly connected to the input terminals 12S and 12T without at least one of the reactors 18S and 18T. That is, the reactor 18 (reactor 18R) may be connected between the input terminal 12I (input terminal 12R) corresponding to the idle circuit and the switch 26.

(modification 2)

Fig. 3 is a circuit configuration diagram of the power conversion device 10 in modification 2. Unlike the above-described embodiment, in modification 2, a capacitor 60 for power storage, which is a passive element, is connected between the output line 42d and the power supply-side terminal 50R of the reactor 18R connected to the input terminal 12R to which the single-phase ac power supply 24 is not connected.

When the voltage of the capacitor 14 detected by the voltage detection unit 20a exceeds a predetermined threshold value, the control unit 20 controls the switching element 36Ru on the upper arm side connected to the input terminal 12R to be turned on. This discharges the electric charge stored in the capacitor 14, and charges the storage capacitor 60. At this time, the control unit 20 prohibits the control of the 36Su, 36Sd, 36Tu, and 36Td connected to the input terminals 12S and 12T, and thus does not perform power regeneration for returning the regenerative energy generated from the motor 22 to the power supply side. Thus, the power conversion device 10 can charge the storage capacitor 60 with surplus power using the power element unit 30R as an idle circuit. Then, the energy stored in the storage capacitor 60 can be discharged and supplied to the converter 16. In the initial operation of the motor drive device, a large current such as a rush current is supplied from the single-phase ac power supply 24, but in the power conversion device 10 of modification 2, a current is also supplied from the storage capacitor 60. Therefore, the storage capacitor 60 functions as a peak clipping device for clipping the peak of the single-phase ac power supply 24. In the case of modification 2, the switch 26 may be directly connected to the input terminals 12S and 12T without at least one of the reactors 18S and 18T. That is, the reactor 18 (reactor 18R) may be connected between the input terminal 12I (input terminal 12R) corresponding to the idle circuit and the switch 26.

[ invention that can be obtained by the embodiment ]

Hereinafter, an invention that can be grasped from the above-described embodiment and the modified examples will be described.

A power conversion device (10) is provided with: a converter (12) having input terminals (12I, 12R, 12S, 12T) and switching elements (36, 36u, 36d, 36Ru, 36Rd, 36Su, 36Sd, 36Tu, 36Td) corresponding to the respective three-phase AC power supplies, and converting an AC voltage of the three-phase AC power supplies into a DC voltage; and a capacitor (14) that smoothes the DC voltage converted by the converter (12). A single-phase AC power supply (24) or a DC power supply is connected to two input terminals (12I, 12R, 12S, 12T) corresponding to any two of the three phases of the converter (12), and a passive element is connected so that one input terminal (12I, 12R, 12S, 12T) corresponding to a phase to which the single-phase AC power supply (24) or the DC power supply is not connected is connected to one end of the capacitor (14).

This makes it possible to provide a circuit configuration that can effectively utilize the idle circuit.

The power conversion device (10) may include: a voltage detection unit (20a) that detects the voltage of the capacitor (14); and a control unit (20) that controls the switching elements (36, 36u, 36d, 36Ru, 36Rd, 36Su, 36Sd, 36Tu, 36Td) corresponding to the respective converters (12). When the voltage of the capacitor (14) exceeds a threshold value, the control unit (20) may turn on the switching elements (36, 36u, 36d, 36Ru, 36Rd, 36Su, 36Sd, 36Tu, 36Td) corresponding to the input terminals (12I, 12R, 12S, 12T) to which the single-phase AC power supply (24) or the DC power supply is not connected, and discharge the charge stored in the capacitor (14).

Reactors (18, 18R, 18S, 18T) may be connected to the power supply side of at least one input terminal (12I, 12R, 12S, 12T) among the three input terminals (12I, 12R, 12S, 12T) of the converter (12), and the passive element may be a discharge resistor (46) connected to the input terminals (12I, 12R, 12S, 12T) of the reactors (18, 18R, 18S, 18T) or the power supply side of the reactors (18, 18R, 18S, 18T) and one end of the capacitor (14).

The control unit (20) may control the switching elements (36, 36u, 36d, 36Ru, 36Rd, 36Su, 36Sd, 36Tu, 36Td) corresponding to two phases to which the single-phase AC power supply (24) or the DC power supply is connected, to perform power regeneration, while discharging the charge accumulated in the capacitor (14) by turning on the switching elements (36, 36u, 36d, 36Ru, 36Rd, 36Su, 36Sd, 36Tu, 36Td) corresponding to the phases to which the single-phase AC power supply (24) or the DC power supply is not connected. This enables the regenerated electric power to be effectively used.

Reactors (18, 18R, 18S, 18T) may be connected to the power supply side of at least one input terminal (12I, 12R, 12S, 12T) of the three input terminals (12I, 12R, 12S, 12T) of the converter (12), and the passive element may be a capacitor (60) for power storage, and the power supply side of the reactors (18, 18R, 18S, 18T) and one end of the capacitor (14) may be connected to each other. Thus, the storage capacitor (60) can be charged with surplus power, and energy stored in the storage capacitor (60) can be discharged and supplied to the converter (16).

The control unit (20) may be configured to discharge the charge accumulated in the capacitor (14) and charge the storage capacitor (60) by turning on the switching elements (36, 36u, 36d, 36Ru, 36Rd, 36Su, 36Sd, 36Tu, 36Td) corresponding to the phases to which the input terminals (12I, 12R, 12S, 12T) of the single-phase AC power supply (24) or the DC power supply are not connected, and to prohibit the control of the switching elements (36, 36u, 36d, 36Ru, 36Rd, 36Su, 36Sd, 36Tu, 36Td) corresponding to the two phases to which the single-phase AC power supply (24) or the DC power supply is connected. This allows the power storage capacitor 60 to be charged with priority.