WO2019049301A1

WO2019049301A1 - Converter and uninterruptible power supply device using same

Info

Publication number: WO2019049301A1
Application number: PCT/JP2017/032409
Authority: WO
Inventors: 宏樹茂田; 俊秀中野
Original assignee: 東芝三菱電機産業システム株式会社
Priority date: 2017-09-08
Filing date: 2017-09-08
Publication date: 2019-03-14

Abstract

A converter (1) is provided with first to sixth arms (A1-A6) each including an IGBT (4), a first diode (D1), and a second diode (D2). The IGBT and the first diode are connected in reverse parallel to each other. The second diode is connected in parallel to the first diode. The IGBT and the first diode are mounted on a first semiconductor module (M1). The second diode (M2) is mounted on a second semiconductor module (M2) different in kind from the first semiconductor module.

Description

Converter and uninterruptible power supply using the same

The present invention relates to a converter and an uninterruptible power supply using the same, and more particularly to a converter that converts alternating current power to direct current power and an uninterruptible power supply using the converter.

For example, Japanese Patent Laid-Open No. 2002-335680 discloses a converter which converts three-phase AC power supplied to three input terminals into DC power and outputs the DC power to the first and second output terminals. The converter comprises first to sixth arms. The first to third arms are respectively connected between the first output terminal and the three input terminals. The fourth to sixth arms are respectively connected between the three input terminals and the second output terminal. Each of the first to sixth arms is configured of one semiconductor module. The semiconductor module includes transistors and diodes connected in antiparallel.

JP 2002-335680 A

In such a converter, when the load capacity is large, in order to suppress the temperature rise of the semiconductor module, each arm is formed of a plurality of semiconductor modules connected in parallel (see FIG. 4).

However, if the powering power supplied from the AC power supply to the load via the converter is larger than the regenerative power supplied from the load to the AC power supply via the converter, the current flowing through the diode is higher than the current flowing through the transistor growing. In this case, when each arm is formed of a plurality of semiconductor modules connected in parallel in order to suppress the temperature rise of the diode, the number of transistors is increased more than necessary and the cost is increased.

Therefore, the main object of the present invention is to provide a low cost converter.

A converter according to the present invention is a converter that converts AC power supplied to a plurality of input terminals into DC power and outputs the DC power to the first and second output terminals, and is provided corresponding to each input terminal, A first arm connected between the first output terminal and the corresponding input terminal, and provided corresponding to each input terminal, connected between the corresponding input terminal and the second output terminal And a second arm. Each of the first and second arms includes a first transistor and a first diode connected in anti-parallel to each other, and a second diode connected in parallel to the first diode. The first transistor and the first diode are mounted on a first semiconductor module, and the second diode is mounted on a second semiconductor module of a type different from the first semiconductor module.

In the converter according to the present invention, each arm includes a first transistor and a first diode connected in anti-parallel, and a second diode connected in parallel to the first diode, and the first transistor and The first diode is mounted on a first semiconductor module, and the second diode is mounted on a second semiconductor module different in type from the first semiconductor module. Therefore, since the second diode is added to each arm, cost reduction of the device can be achieved as compared with the case where each arm is configured by a plurality of sets of the first transistor and the first diode.

It is a circuit block diagram which shows the structure of the power converter device by Embodiment 1 of this invention. It is a circuit diagram which shows the structure of the arm shown in FIG. FIG. 7 is a circuit diagram showing a comparative example 1 of the first embodiment. FIG. 13 is a circuit diagram showing another comparative example 2 of the first embodiment. It is a circuit block diagram which shows the structure of the power converter device by Embodiment 2 of this invention. It is a circuit block diagram which shows the structure of the uninterruptible power supply by Embodiment 3 of this invention. It is a circuit block diagram which shows the structure of the power converter device by Embodiment 4 of this invention. It is a circuit diagram which shows the structure of the alternating current switch shown in FIG. FIG. 21 is a circuit diagram showing a modification of the fourth embodiment. It is a circuit block diagram which shows the structure of the uninterruptible power supply by Embodiment 5 of this invention.

First Embodiment
FIG. 1 is a circuit block diagram showing a configuration of a power conversion device according to a first embodiment of the present invention. In FIG. 1, this power conversion device includes AC input terminals T1 to T3 and DC output terminals T4 and T5. AC input terminals T1 to T3 receive three-phase AC power of commercial frequency from commercial AC power supply 51. The DC output terminals T4 and T5 are connected to the load 52. The load 52 is driven by DC power supplied from the power conversion device. The power running power supplied from the commercial AC power supply 51 to the load 52 via the converter 1 is sufficiently larger than the regenerative power supplied from the load 52 to the commercial AC power supply 51 via the converter 1.

The power converter further includes a converter 1, a DC positive bus L 1, a DC negative bus L 2, a capacitor 12, and a controller 13. Converter 1 is controlled by control device 13, converts three-phase AC power supplied from commercial AC power supply 51 into DC power, and outputs it between DC positive bus L1 and DC negative bus L2.

That is, converter 1 includes six arms A1 to A6. Each of the arms A1 to A6 has a positive terminal 2 and a negative terminal 3. The positive terminals 2 of the arms A1 to A3 are all connected to the DC output terminal T4 via the DC positive bus L1. The negative terminals 3 of the arms A1 to A3 are connected to the AC input terminals T1 to T3, respectively. The positive terminals 2 of the arms A4 to A6 are connected to the AC input terminals T1 to T3, respectively. The negative terminals 3 of the arms A1 to A3 are all connected to the DC output terminal T5 via the DC negative bus L2.

FIG. 2 is a circuit diagram showing the configuration of the arm A1. In FIG. 2, the arm A1 includes two semiconductor modules M1 and M2 of different types. The semiconductor module M1 includes an IGBT (Insulated Gate Bipolar Transistor) 4, a diode D1, a collector terminal 5, an emitter terminal 6, and a gate terminal 7.

The collector of the IGBT 4 is connected to the collector terminal 5, its emitter is connected to the emitter terminal 6, and its gate is connected to the gate terminal 7. The gate terminal 7 is connected to the control device 13. When the gate terminal 7 is set to the “H” level, the IGBT 4 is turned on, and when the gate terminal 7 is set to the “L” level, the IGBT 4 is turned off.

The anode of the diode D1 is connected to the emitter terminal 6 and its cathode is connected to the collector terminal 5. That is, IGBT 4 and diode D 1 are connected in anti-parallel between collector terminal 5 and emitter terminal 6.

When the voltage between emitter terminal 6 and collector terminal 5 is larger than predetermined on voltage Von1, diode D1 is turned on, and when the voltage between emitter terminal 6 and collector terminal 5 is smaller than predetermined on voltage Von1, diode D1 Turns off. Collector terminal 5 and emitter terminal 6 are connected to positive side terminal 2 and negative side terminal 3 of arm A1, respectively.

The semiconductor module M2 includes a diode D2, a cathode terminal 10, and an anode terminal 11. The cathode and the anode of the diode D2 are connected to the cathode terminal 10 and the anode terminal 11, respectively.

When the voltage between anode terminal 11 and cathode terminal 10 is larger than predetermined on voltage Von2, diode D2 is turned on, and when the voltage between anode terminal 11 and cathode terminal 10 is smaller than predetermined on voltage Von2, diode D2 Turns off. The on voltage Von2 of the diode D2 is smaller than the on voltage Von1 of the diode D1.

The cathode terminal 10 and the anode terminal 11 are respectively connected to the positive terminal 2 and the negative terminal 3 of the arm A1. Therefore, the diodes D1 and D2 are connected in parallel between the positive terminal 2 and the negative terminal 3. Since the on voltage Vo2 of the diode D2 is smaller than the on voltage Vo1 of the diode D1, the diode D2 is turned on earlier than the diode D1. The current flowing through the diode D2 is larger than the current flowing through the diode D1.

Thus, the arm A1 is substantially constituted by the IGBT 4 and the diode D2 connected in antiparallel between the positive terminal 2 and the negative terminal 3. The IGBT 4 mainly supplies a regenerative current, and the diode D2 mainly supplies a powering current. As described above, the power running power supplied from the commercial AC power supply 51 to the load 52 via the converter 1 is larger than the regenerative power returned from the load 52 to the commercial AC power supply 51 via the converter 1. Therefore, the current flowing through the diode D2 is larger than the current flowing through the IGBT4.

The size of the IGBT 4 (that is, the type of the semiconductor module M1) is selected so as to suppress the temperature rise of the IGBT 4 due to the regenerative current. Further, the size of the diode D2 (that is, the type of the semiconductor module M2) is selected so as to suppress the temperature rise of the diode D2 due to the powering current. The other arms A2 to A6 have the same configuration as the arm A1.

Referring back to FIG. 1, capacitor 12 is connected between DC positive bus L1 and DC negative bus L2 to smooth the output voltage of converter 1. The capacitor 12 may be included in the converter 1.

Three-phase AC voltages V1 to V3 from commercial AC power supply 51 are full-wave rectified by six diodes D2 included in arms A1 to A6 of converter 1, and smoothed by capacitor 12 to become DC voltage VDC. The powering current mainly flows through six diodes D2.

Control device 13 operates in synchronization with AC voltages V1 to V3 of AC input terminals T1 to T3 so that DC voltage VDC between DC output terminals T4 and T5 becomes a predetermined target DC voltage VDCT. The six IGBTs 4 included in the arms A1 to A6 are controlled.

That is, control device 13 controls six IGBTs 4, converts DC voltage VDC between DC output terminals T4 and T5 into three-phase AC voltages V11 to V13, and outputs the voltage between AC input terminals T1 to T3.

When DC voltage VDC is lower than target DC voltage VDCT, control device 13 controls six IGBTs 4 to set the phases of three-phase AC voltages V11 to V13 to three-phase AC voltages V1 to V3 of commercial AC power supply 51. Delay more than phase. As a result, the power running current is supplied from the commercial AC power supply 51 to the capacitor 12 via the six IGBTs 4, and the DC voltage VDC rises.

Conversely, when the DC voltage VDC is higher than the target DC voltage VDCT, the control device 13 controls the six IGBTs 4 to set the phases of the three-phase AC voltages V11 to V13 to the three-phase AC voltage V1 of the commercial AC power supply 51. Advance to the phase of ~ V3. Thus, power is supplied from the capacitor 12 to the commercial AC power supply 51 via the converter 1, and the DC voltage VDC falls. Therefore, by controlling six IGBTs 4, DC voltage VDC can be made the target DC voltage VDCT. The maximum value of the DC output voltage VDC is the peak value of the AC input voltage.

Since the power running current is always supplied from the commercial AC power supply 51 to the capacitor 12 via the six diodes D2, the power running current flowing through the IGBT 4 is small. Further, in the first embodiment, since the regenerative power generated by load 52 is small, there are few cases where DC voltage VDC is higher than target DC voltage VDCT, and the regenerative current flowing through IGBT 4 is small. Therefore, the current flowing through the diode D2 is larger than the current flowing through the IGBT4.

FIG. 3 is a circuit diagram showing a comparative example 1 of the first embodiment, which is to be compared with FIG. Referring to FIG. 3, this comparative example 1 is different from the embodiment 1 in that each of arms A1 to A6 is replaced with arm 15. The arm 15 is obtained by removing the semiconductor module M2 from the arm A1 (FIG. 2), and includes only one semiconductor module M1.

In this comparative example 1, there is no problem when the load current is small, but when the load current is large, the temperature rise of the semiconductor module M1 becomes excessive and there is a problem that the semiconductor module M1 is damaged.

FIG. 4 is a circuit diagram showing another comparative example 2 of the first embodiment, which is to be compared with FIG. Referring to FIG. 4, this comparative example 2 is different from the embodiment 1 in that each of arms A1 to A6 is replaced with arm 16. The arm 16 is formed by connecting a plurality of semiconductor modules M2 in parallel. The plurality of collector terminals 5 are all connected to the positive terminal 2, the plurality of emitter terminals 6 are all connected to the negative terminal 3, and the plurality of gate terminals 7 are connected to each other.

In the second comparative example, the load current is shunted to the plurality of semiconductor modules M1, so that the current flowing through one semiconductor module M1 can be reduced to a fraction of the load current. Therefore, even when the load current is large, the temperature rise of the semiconductor module M1 can be suppressed.

However, this comparative example 2 has the following problems. That is, depending on the type of load, the powering power may be larger than the regenerative power. In this case, the current flowing through the diode D1 becomes larger than the current flowing through the IGBT 4, and the temperature rise of the diode D1 becomes higher than the temperature rise of the IGBT 4. In this case, when the arm 16 is configured by connecting a plurality of semiconductor modules M1 in parallel in order to suppress the temperature rise of the diode D1, the number of IGBTs 4 increases more than necessary and the cost increases.

Furthermore, in the semiconductor module M1 that is commercially available, the characteristics of the IGBT 4 vary, and the characteristics of the diode D1 (for example, the on voltage Von1) also vary. Although the variation in the characteristics of the IGBT 4 is small depending on the type of the semiconductor module M1, the variation in the characteristics of the diode D1 is large. Therefore, in the second comparative example, the on-voltage Von1 of the plurality of diodes D1 connected in parallel causes a smaller current to flow through the smaller diode D1, and the temperature rise of the diode D1 increases. For this reason, in the comparative example 2, in order to suppress the temperature rise of the diode D1, it is necessary to connect many semiconductor modules M1 in parallel, which results in an increase in cost.

On the other hand, in the first embodiment, the diode D2 having a small temperature rise is connected in parallel to the semiconductor module M1 even if the powering current is supplied to the load 52, so the number of IGBTs 4 is more than necessary as in the second comparative example. It will not be expensive and expensive.

In the first embodiment, the case where the IGBT 4 and the diode D1 are mounted on one semiconductor module M1 and the diode D2 is mounted on one semiconductor module M2 in each of the arms A1 to A6 has been described. However, the N sets of IGBTs 4 and diodes D1 of the N arms may be mounted on the same semiconductor module, and the N diodes D2 of the N arms may be mounted on another semiconductor module. However, N is an integer from 2 to 6.

For example, arms A1 to A6 are grouped by two, and in each arm group, two sets of IGBT 4 and diode D1 are mounted in one semiconductor module, and two diodes D2 are mounted in another semiconductor module It does not matter. In this case, the number of semiconductor modules is six.

Also, six pairs of IGBT 4 and six diodes A1 to A6 and one diode D1 are mounted on one semiconductor module, and six diodes D2 of six arms A1 to A6 are mounted on another semiconductor module. I don't care. In this case, the number of semiconductor modules is two.

In the first embodiment, the present invention is applied to the converter 1 for converting three-phase AC power to DC power. However, the present invention relates to a single-phase converter for converting single-phase AC power to DC power. It goes without saying that it is also applicable to The single-phase converter is obtained by removing the AC input terminal T3 and the arms A3 and A6 from the converter 1 of FIG.

Second Embodiment
FIG. 5 is a circuit block diagram showing a configuration of a power conversion device according to a second embodiment of the present invention, which is to be compared with FIG. Referring to FIG. 5, this power conversion device differs from the power conversion device of FIG. 1 in that reactors 21 to 23 are added and control device 13 is replaced with control device 13A.

One terminal of the reactor 21 is connected to the AC input terminal T1, and the other terminal is connected to the negative terminal 3 of the arm A1 and the positive terminal 2 of the arm A4. One terminal of reactor 22 is connected to AC input terminal T2, and the other terminal is connected to negative terminal 3 of arm A2 and positive terminal 2 of arm A5. One terminal of the reactor 23 is connected to the AC input terminal T3, and the other terminal is connected to the negative terminal 3 of the arm A3 and the positive terminal 2 of the arm A6.

In addition to the operation of control device 13, control device 13A charges capacitor 12 using the electromagnetic energy of reactors 21-23. For example, when the voltage of the AC input terminal T1 is high and the voltage of the AC input terminal T2 is high, the control device 13A turns on the IGBT 4 (FIG. 2) of the arm A4. As a result, current flows from the AC input terminal T1 to the AC input terminal T2 through the reactor 21, the IGBT 4 of the arm A4, the diode D2 of the arm A5, and the reactor 22 and electromagnetic energy is accumulated in the reactors 21 and 22.

Next, the control device 13A turns off the IGBT 4 of the arm A4. As a result, the current flowing through the reactors 21 and 22 is diverted to the diode D2 of the arm A1, the capacitor 12 and the diode D2 of the arm A5, so that the electromagnetic energy of the reactors 21 and 22 is released and the capacitor 12 is charged. The current flowing through capacitor 12 can be adjusted by adjusting the ratio of the on time to the off time of IGBT 4, and the DC output voltage VDC of converter 1 can be adjusted. The other configuration and operation are the same as in the first embodiment, and the description thereof will not be repeated.

In the first embodiment in which the electromagnetic energy of reactors 21 to 23 is not used, DC output voltage VDC can not be made higher than the peak value of AC input voltage. On the other hand, in the second embodiment, since the electromagnetic energy of the reactors 21 to 23 is used, the DC output voltage VDC can be made higher than the peak value of the AC input voltage VDC. However, since the current for storing the electromagnetic energy is supplied to the IGBT 4 in the reactors 21 to 23, the current flowing in the IGBT 4 becomes larger than that in the first embodiment.

Third Embodiment
6 is a circuit block diagram showing a configuration of an uninterruptible power supply according to a third embodiment of the present invention. In FIG. 6, the uninterruptible power supply device includes AC input terminals T1 to T3, AC output terminals T11 to T13, and battery terminals T21 and T22.

AC input terminals T1 to T3 receive three-phase AC power from commercial AC power supply 51. The AC output terminals T11 to T13 are connected to the load 53. The load 53 is driven by three-phase AC power supplied from an uninterruptible power supply. The battery terminals T21 and T22 are connected to the positive electrode and the negative electrode of the battery 54 (power storage device), respectively. The battery 54 stores DC power. A capacitor may be connected instead of the battery 54.

The uninterruptible power supply further includes a converter 1, a DC positive bus L1, a DC negative bus L2, a capacitor 12, an inverter 25, and a controller 26. The configuration of converter 1 is as shown in FIGS. 1 and 2. Three input nodes of converter 1 are connected to AC input terminals T1 to T3, and three output nodes of inverter 25 are connected to AC output terminals T11 to T13.

The DC positive bus L1 and the DC negative bus L2 are connected between the converter 1 and the inverter 25 and connected to the battery terminals T21 and T22, respectively. Capacitor 12 is connected between DC positive bus L1 and DC negative bus L2, and smoothes DC voltage VDC between buses L1 and L2.

Converter 1 is controlled by control device 26. When AC voltages V1 to V3 of commercial AC power supply 51 are normal, three-phase AC power from commercial AC power supply 51 is converted to DC power to drive DC positive bus L1 and Output to DC negative bus L2. The DC power generated by the converter 1 is supplied to the inverter 25 and stored in the battery 54.

At this time, converter 1 outputs a DC current such that DC voltage VDC between DC positive bus L1 and DC negative bus L2 becomes target DC voltage VDCT. When the AC voltages V1 to V3 of the commercial AC power supply 51 are not normal (for example, when a power failure occurs), the operation of converter 1 is stopped.

The inverter 25 is controlled by the control device 26. When the AC voltages V1 to V3 of the commercial AC power supply 51 are normal, the DC power generated by the converter 1 is converted to three-phase AC power of the commercial frequency to obtain the load 53 Supply to Further, when the AC voltages V1 to V3 of the commercial AC power supply 51 are not normal, the inverter 25 converts the DC power of the battery 54 into three-phase AC power of commercial frequency and supplies it to the load 53. Inverter 25 is a known circuit including a plurality of sets of IGBTs and diodes.

Control device 26 detects instantaneous values of AC input voltages V1 to V3 of commercial AC power supply 51, instantaneous values of DC voltage VDC between buses L1 and L2, and instantaneous values of AC output voltages VO1 to VO3 of inverter 25, The entire uninterruptible power supply is controlled based on the detected values.

That is, the control device 26 determines whether or not the detected values of the AC input voltages V1 to V3 are normal. For example, when the commercial AC power supply 51 is healthy, the AC input voltages V1 to V3 have values within the normal range. When a power failure of the commercial AC power supply 51 occurs, at least one of the AC input voltages V1 to V3 falls below the lower limit value of the normal range. When at least one of the AC input voltages V1 to V3 is lower than the lower limit value, the control device 26 determines that the AC input voltages V1 to V3 are not normal.

Further, control device 26 controls each of converter 1 and inverter 25 in synchronization with the phases of AC input voltages V1 to V3. At this time, control device 26 controls each IGBT 4 of converter 1 such that output voltage VDC of converter 1 becomes target DC voltage VDCT. Further, control device 26 controls each IGBT of inverter 25 such that output voltages VO1 to VO3 of inverter 25 become target AC voltages VOT1 to VOT3.

Next, the operation of this uninterruptible power supply will be described. When the AC voltages V1 to V3 of the commercial AC power supply 51 are normal, three-phase AC power from the commercial AC power supply 51 is converted by the converter 1 into DC power. The DC power generated by the converter 1 is supplied to the inverter 25 and stored in the battery 54. The inverter 25 converts the DC power from the converter 1 into three-phase AC power and supplies it to the load 53.

When the AC voltages V1 to V3 of the commercial AC power supply 51 are not normal, the operation of the converter 1 is stopped, and the DC power of the battery 54 is converted into three-phase AC power by the inverter 25 and supplied to the load 53. Therefore, even when a power failure of the commercial AC power supply 51 occurs, the operation of the load 53 can be continued while DC power is stored in the battery 54.

The same effects as in the first embodiment can be obtained in the third embodiment.
Fourth Embodiment
FIG. 7 is a circuit block diagram showing a configuration of a power conversion device according to a fourth embodiment of the present invention, which is to be compared with FIG. Referring to FIG. 7, this power converter differs from the power converter of FIG. 1 in that converter 1 is replaced by converter 31, capacitor 12 is replaced by capacitors C1 and C2, and neutral point terminal T6 ( 3) is added, and the controller 13 is replaced by the controller 36.

Converter 31 is obtained by adding AC switches S1 to S3 to converter 1. One terminals 32 of the AC switches S1 to S3 are respectively connected to the AC input terminals T1 to T3, and the other terminals of the AC switches S1 to S3 are both connected to the neutral point terminal T6.

AC switch S1 includes

IGBTs

34 and 35 and diodes D3 and D4 as shown in FIG. The collectors of

IGBTs

34 and 35 are connected to each other, and their emitters are connected to one terminal 32 and the other terminal 33, respectively. The gates of the

IGBTs

34 and 35 are connected to the controller 36.

The anode and the cathode of the diode D3 are respectively connected to the emitter and the collector of the IGBT 34, and the anode and the cathode of the diode D4 are respectively connected to the emitter and the collector of the IGBT 35. That is, the diodes D3 and D4 are connected in anti-parallel to the

IGBTs

34 and 35, respectively.

When the gates of the

IGBTs

34 and 35 are set to the “L” level and the “H” level, respectively, the IGBT 34 is turned off and the IGBT 35 is turned on, and a current flows from one terminal 32 to the other terminal 33 via the diode D3 and the IGBT 35.

When the gates of the

IGBTs

34 and 35 are set to the “H” level and the “L” level, respectively, the IGBT 34 is turned on and the IGBT 35 is turned off, and a current flows from the other terminal 33 to the one terminal 32 via the diode D4 and the IGBT 34.

The IGTB 34 and the diode D3 may be configured by one semiconductor module, or may be configured by a plurality of semiconductor modules connected in parallel. The IGTB 35 and the diode D4 may be configured by one semiconductor module, or may be configured by a plurality of semiconductor modules connected in parallel. Each of the AC switches S2 and S3 has the same configuration as the AC switch S1.

Returning to FIG. 7, capacitor C1 is connected between DC positive bus L1 and neutral point terminal T6 to smooth the DC voltage between DC positive bus L1 and neutral point terminal T6. Capacitor C2 is connected between neutral point terminal T6 and DC negative bus L2, and smoothes the DC voltage between neutral point terminal T6 and DC negative bus L2.

The control device 36 operates in synchronization with the AC voltages V1 to V3 of the AC input terminals T1 to T3 so that the arm A1 to A5 may operate such that the DC voltage VDC between the DC output terminals T4 and T5 becomes a predetermined target DC voltage VDCT. A total of six IGBTs 4 included in A6 are controlled, and a total of six

IGBTs

34 and 35 included in the AC switches S1 to S3 are controlled.

For example, when the voltage of the AC input terminal T1 (FIG. 7) is higher than the voltage of the AC input terminal T2, the control device 36 turns on the IGBT 34 of the AC switch S2 and turns off the IGBT 35. Thereby, current flows from the AC input terminal T1 to the AC input terminal T2 through the diode D2 of the arm A1, the capacitor C1, the diode D4 of the AC switch S2, and the IGBT 34 of the AC switch S2, and the capacitor C1 is charged.

Further, when the voltage of the AC input terminal T1 is higher than the voltage of the AC input terminal T2, the control device 36 turns off the IGBT 34 of the AC switch S1 and turns on the IGBT 35. Thereby, current flows from the AC input terminal T1 to the AC input terminal T2 through the diode D3 of the AC switch S1, the IGBT 35 of the AC switch S1, the capacitor C2 and the diode D2 of the arm A5, and the capacitor C2 is charged.

Capacitors C1 and C2 are charged equally. As a result, assuming that DC voltages of the DC output terminal T4, the DC output terminal T5, and the neutral point terminal T6 are VDC1 to VDC3, respectively, VDC1-VDC2 = VDCT, VDC1-VDC3 = VDC3-VDC2 = VDCT / 2. Further, when the DC neutral point bus L3 is grounded and VDC3 = 0 V, VDC1 becomes a positive voltage, VDC2 becomes a negative voltage, and VDC1 = -VDC2. Further, since the voltage obtained by adding the terminal voltages of the two capacitors C1 and C2 is the DC output voltage VDC, the maximum value of the DC output voltage VDC is a voltage twice the peak value of the AC input voltage.

In other words, control device 36 controls 12 IGBTs 4, 4 and 35, generates three-phase AC voltages V11 to V13 based on DC voltages VDC1 to VDC3, and generates generated three-phase AC voltages V11 to V13 respectively. Output to alternating current input terminals T1 to T3.

When DC voltage VDC is lower than target DC voltage VDCT, control device 36 controls 12 IGBTs 4, 4 and 35 so that the phases of three-phase AC voltages V11 to V13 are three-phase AC voltages of commercial AC power supply 51. Delay from the phase of V1 to V3. Thus, the powering current is supplied from the commercial AC power supply 51 to the capacitors C1 and C2 via the arms A1 to A6 and the AC switches S1 to S3, and the DC voltage VDC rises.

On the contrary, when DC voltage VDC is higher than target DC voltage VDDT, control device 36 controls 12

IGBTs

4, 3, 34 and 35 so that the phases of three-phase AC voltages V11 to V13 are three. The phase AC voltage V1 to V3 are advanced. As a result, electric power is supplied from the capacitors C1 and C2 to the commercial AC power supply 51 via the converter 31, and the DC voltage VDC falls. Therefore, by controlling the twelve

IGBTs

4, 3, 34, the DC voltage VDC can be made the target DC voltage V DCT.

In the fourth embodiment, the DC output voltage VDC is higher than the peak value of the AC input voltage without using the electromagnetic energy of the reactors 21 to 23 (FIG. 5) (twice of the peak value of the AC input voltage Voltage). Therefore, since it is not necessary to flow a current for storing electromagnetic energy in reactors 21 to 23 to IGBTs 4 of arms A1 to A6, the size of IGBT 4 (size of semiconductor module M1) can be reduced. Therefore, the effect of the present invention in which each of the arms A1 to A6 is configured by the semiconductor modules M1 and M2 (FIG. 2) is larger than that of the second embodiment (FIG. 5).

FIG. 9 is a circuit diagram showing a modification of the fourth embodiment, which is to be compared with FIG. Referring to FIG. 9, in this modification, each of switches S1 to S3 (FIG. 7) is replaced with switch 36. Switch 36 includes

IGBTs

34 and 35 and diodes D3 and D4.

The emitters of

IGBTs

34 and 35 are connected to each other, and the collectors of

IGBTs

35 and 34 are connected to one terminal 32 and the other terminal 33, respectively. The gates of the

IGBTs

34 and 35 are connected to the controller 36.

IGBTs

34 and 35, respectively.

When the gates of the

IGBTs

34 and 35 are set to the “L” level and the “H” level, respectively, the IGBT 34 is turned off and the IGBT 35 is turned on, and a current flows from one terminal 32 to the other terminal 33 via the IGBT 35 and the diode D3.

When the gates of the

IGBTs

34 and 35 are set to the “H” level and the “L” level, respectively, the IGBT 34 is turned on and the IGBT 35 is turned off, and a current flows from the other terminal 33 to the one terminal 32 via the IGBT 34 and the diode D4. Also in this modification, the same effect as that of the fourth embodiment can be obtained.

Fifth Embodiment
FIG. 10 is a circuit block diagram showing a configuration of an uninterruptible power supply according to a fifth embodiment of the present invention, which is to be compared with FIG. 10, this uninterruptible power supply differs from the uninterruptible power supply of FIG. 6 in that converter 1, capacitor 12, inverter 25 and control device 26 each have three levels of converter 31 (FIG. 7), capacitor C1, C2 (FIG. 7), a 3-level inverter 40, and a control device 41 are substituted, and a DC neutral point bus L3 is added.

The configuration of converter 31 is as shown in FIGS. 7 and 8. Three input nodes of converter 31 are connected to AC input terminals T1 to T3, and three output nodes of inverter 40 are connected to AC output terminals T11 to T13.

DC positive bus L 1, DC negative bus L 2, and DC neutral point bus L 3 are connected between converter 31 and inverter 40. DC positive bus L1 and DC negative bus L2 are connected to battery terminals T21 and T22, respectively. Capacitor C1 is connected between DC positive bus L1 and DC neutral point bus L3 to smooth DC voltage VDC / 2 between buses L1 and L3. Capacitor C2 is connected between DC neutral point bus L3 and DC negative bus L2 and smoothes DC voltage VDC / 2 between buses L3 and L2.

Converter 31 is controlled by control device 41, and when AC voltages V1 to V3 of commercial AC power supply 51 are normal, three-phase AC power from commercial AC power supply 51 is converted to DC power to carry out DC positive bus L1, It outputs to DC negative bus L2 and DC neutral point bus L3. The DC power generated by converter 31 is supplied to inverter 40 and stored in battery 54.

At this time, converter 31 equally charges capacitors C1 and C2 such that DC voltage VDC between DC positive bus L1 and DC negative bus L2 becomes target DC voltage VDCT. Assuming that DC voltages of DC positive bus L1, DC negative bus L2, and DC neutral bus L3 are VDC1 to VDC3, respectively, VDC1-VDC2 = VDCT, VDC1-VDC3 = VDC3-VDC2 = VDCT / 2.

Further, when the DC neutral point bus L3 is grounded and VDC3 = 0 V, VDC1 becomes a positive voltage, VDC2 becomes a negative voltage, and VDC1 = -VDC2. When the AC voltages V1 to V3 of the commercial AC power supply 51 are not normal (for example, when a power failure occurs), the operation of the converter 31 is stopped.

The inverter 40 is controlled by the control device 41, and when the AC voltages V1 to V3 of the commercial AC power supply 51 are normal, the DC power generated by the converter 31 is converted to three-phase AC power of commercial frequency and the load 53 Supply to At this time, inverter 40 generates three-phase AC voltages VO1 to VO3 using three levels of DC voltages VDC1 to VDC3 from converter 31.

In addition, when the AC voltages V1 to V3 of the commercial AC power supply 51 are not normal, the inverter 40 converts DC power of the battery 54 into three-phase AC power of commercial frequency and supplies it to the load 53. Inverter 40 is a known circuit including a plurality of sets of IGBTs and diodes.

Control device 41 detects instantaneous values of AC input voltages V1 to V3 of commercial AC power supply 51, instantaneous values of DC voltage VDC between buses L1 and L2, and instantaneous values of AC output voltages VO1 to VO3 of inverter 40, The entire uninterruptible power supply is controlled based on the detected values.

The other configuration and operation are the same as in the uninterruptible power supply of FIG. 6, and thus the description thereof will not be repeated. Also in the fifth embodiment, the same effect as the fourth embodiment can be obtained.

It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The present invention is shown not by the above description but by the claims, and is intended to include all modifications within the scope and meaning equivalent to the claims.

T1 to T3 AC input terminals, T4 and T5 DC output terminals, 1,31 converters, A1 to A6, 15, 16 arms, 2 positive terminals, 3 negative terminals, M1, M2 semiconductor modules, 4, 34, 35 IGBTs , D1 to D4 diodes, 5 collector terminals, 6 emitter terminals, 7 gate terminals, 10 cathode terminals, 11 anode terminals, L1 DC positive bus, L2 DC negative bus, L3 DC neutral bus, 12, C1, C2 capacitors, 13, 13 A, 26, 41 controller, 21 to 23 reactors, 25, 40 inverters, T11 to T13 AC output terminals, T21, T22 battery terminals, S1 to S3, 36 switches, 51 commercial AC power supplies, 52, 53 loads, 54 battery.

Claims

A converter that converts AC power supplied to a plurality of input terminals into DC power and outputs the DC power to first and second output terminals,
A first arm provided corresponding to each input terminal and connected between the first output terminal and the corresponding input terminal;
A second arm provided corresponding to each input terminal and connected between the corresponding input terminal and the second output terminal;
Each of the first and second arms is
A first transistor and a first diode connected in antiparallel to each other;
And a second diode connected in parallel to the first diode,
The first transistor and the first diode are mounted on a first semiconductor module,
The converter, wherein the second diode is mounted on a second semiconductor module of a type different from the first semiconductor module.
The plurality of input terminals are connected to an AC power supply,
The first and second output terminals are connected to a load,
The converter according to claim 1, wherein the power running power supplied from the AC power supply to the load via the converter is larger than the regenerative power supplied from the load via the converter to the AC power supply.
The converter according to claim 1, wherein the on voltage of the second diode is lower than the on voltage of the first diode.
The converter according to claim 1, wherein the first transistor is an insulated gate bipolar transistor.
The converter according to claim 1, further comprising a capacitor connected between the first and second output terminals.
Furthermore, a third output terminal,
An AC switch provided corresponding to each input terminal and connected between the corresponding input terminal and the third output terminal;
The AC switch is
Second and third transistors whose first electrodes are connected to each other and whose second electrodes are respectively connected to the corresponding input terminal and the third output terminal;
And third and fourth diodes connected in anti-parallel to the second and third transistors, respectively,
The converter generates first to third direct current voltages based on alternating current voltages applied to the plurality of input terminals, and outputs the first to third direct current voltages to the first to third outputs, respectively. The converter according to claim 1, which outputs to a terminal.
The converter according to claim 6, wherein each of the first to third transistors is an insulated gate bipolar transistor.
Furthermore, a first capacitor connected between the first and third output terminals;
The converter according to claim 6, comprising a second capacitor connected between the third and second output terminals.
A converter according to claim 1;
An inverter for converting DC power received from the first and second output terminals into AC power and supplying the AC power to the load;
The plurality of input terminals receive AC power from a commercial AC power supply,
When the AC voltage from the commercial AC power supply is normal, AC power from the commercial AC power supply is converted to DC power by the converter, and the DC power is stored in a power storage device and converted to AC power by the inverter. Converted and supplied to the load,
When the alternating voltage from the commercial alternating current power supply is not normal, the operation of the converter is stopped, and the direct current power of the power storage device is converted into alternating current power by the inverter and supplied to the load .