WO2016098178A1

WO2016098178A1 - Power converter

Info

Publication number: WO2016098178A1
Application number: PCT/JP2014/083242
Authority: WO
Inventors: 秋山　悟; 隆誠藤田
Original assignee: 株式会社日立製作所
Priority date: 2014-12-16
Filing date: 2014-12-16
Publication date: 2016-06-23
Also published as: JP6231225B2; DE112014007164B4; JPWO2016098178A1; DE112014007164T5

Abstract

Provided is a power converter enabling an increase in reliability in a railway vehicle, for example, into which a plurality of AC powers are input from a plurality of AC power overhead contact lines. The power converter has a first converter, a first inverter, a transformer, a second converter, and a second inverter. The first converter converts a first AC power among a plurality of AC powers to a first DC power. The first inverter converts the first DC power to a second AC power. The transformer converts the second AC power to a third AC power. The second converter converts the third AC power to a second DC power. The second inverter converts the second DC power to a fourth AC power. The first converter, first inverter, and second converter are constituted by unipolar elements, and the second inverter is constituted by bipolar elements.

Description

Power converter

The present invention relates to a power converter, for example, a power converter in a railway vehicle that receives a plurality of AC power from a plurality of AC power overhead lines.

As a power conversion technique in a railway vehicle, for example, there is a technique described in Patent Document 1. Patent Document 1 describes a technique related to a converter system used in a railway vehicle drive system. This converter system has a plurality of partial converter systems as a power source for a motor that is a load system. In this converter system, an alternating voltage is supplied to the series circuit of the partial converter system.

Japanese National Patent Publication No. 11-511949

In the technique described in Patent Document 1, the availability is improved by the redundant partial converter system. However, there is a case where there are a plurality of inputs having different voltage values as the AC voltage input to the power converter. Not considered. In addition, as a switching element constituting each converter of the partial converter system, use of a wide band gap element capable of improving reliability by increasing a breakdown voltage or reducing a loss has not been studied.

A typical object of the present invention is to provide a power converter capable of improving reliability in, for example, a railway vehicle that receives a plurality of AC power from a plurality of AC power overhead lines.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

(1) The power converter includes a first converter, a first inverter, a transformer, a second converter, and a second inverter. The first converter converts a first AC power among a plurality of AC powers into a first DC power. The first inverter converts the first DC power into second AC power. The transformer converts the second AC power into third AC power. The second converter converts the third AC power into second DC power. The second inverter converts the second DC power into fourth AC power. The first converter, the first inverter, and the second converter are composed of unipolar elements, and the second inverter is composed of a bipolar element.

(2) The power converter includes a first converter, a first inverter, a transformer, and a second converter. The first converter converts a first AC power among a plurality of AC powers into a first DC power. The first inverter converts the first DC power into second AC power. The transformer converts the second AC power into third AC power. The second converter converts the third AC power into second DC power. The first converter, the first inverter, the transformer, and the second converter constitute one converter group. The breakdown voltage when a plurality of the converter groups are connected in series is higher than the highest voltage among the plurality of AC powers.

(3) The power converter includes a first converter, a first inverter, a transformer, a second converter, a voltage detector, and a control circuit. The first converter converts a first AC power of the plurality of AC powers into a first DC power in a railway vehicle that receives a plurality of AC powers from a plurality of AC power overhead lines. The first inverter converts the first DC power into second AC power. The transformer converts the second AC power into third AC power. The second converter converts the third AC power into second DC power. The voltage detector detects voltages of the plurality of AC powers input to the railway vehicle. The control circuit controls the first converter, the first inverter, and the second converter based on the voltage detected by the voltage detector. The first converter, the first inverter, the transformer, the second converter, the voltage detector, and the control circuit constitute one converter group. In the configuration in which a plurality of the converter groups are connected in series, the power converter includes the plurality of converter groups connected in series and a plurality of short-circuits that short-circuit each of the plurality of converter groups. The plurality of AC powers include a first voltage AC power and a second voltage AC power lower than the first voltage. When the AC power having the second voltage is input, the power converter performs a power conversion operation using a part of the plurality of converter groups.

Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

As a typical effect, for example, in a railway vehicle that receives a plurality of AC power from a plurality of AC power overhead lines, a power converter that can improve reliability can be provided.

It is a block diagram which shows an example of a structure of the rail vehicle using the power converter in Embodiment 1 of this invention. FIG. 2 is a circuit diagram showing an example of a configuration of a converter group and a short circuit constituting a power converter in the railway vehicle of FIG. 1. (A) (b) (c) is explanatory drawing which shows an example of operation | movement of a converter group and a short circuit when a different overhead wire voltage is input into the power converter of FIG. (A) (b) is explanatory drawing which shows an example of the external appearance of the module which accommodates the converter group corresponding to the operation | movement of FIG. 3, and a short circuit. FIG. 3 is a cross-sectional view showing an example of the structure of a semiconductor switch element (SiC-MOS) used in the power converter of FIG. 2. It is sectional drawing which shows an example of the structure of the semiconductor switch element (SiC-IGBT) utilized for the power converter of FIG. (A) and (b) are the top views and sectional drawings which show an example of the structure of the semiconductor diode element (SiC-SBD) utilized for the power converter of FIG. (A) and (b) are the top views and sectional drawings which show an example of the structure of the semiconductor diode element (SiC-PND) utilized for the power converter of FIG. FIG. 2 is a circuit diagram illustrating an example of a configuration of a converter group and a final stage inverter that constitute a power converter in the railway vehicle of FIG. 1.

In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant and one is the other. There are some or all of the modifications, details, supplementary explanations, and the like. Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.
[Outline of the embodiment]

First, the outline of the embodiment will be described. In the outline of the present embodiment, as an example, the reference numerals of the corresponding components of the embodiment are given in parentheses.

(1) The power converter includes a first converter (13), a first inverter (14), a transformer (15), a second converter (16), and a second inverter (21). The first converter converts a first AC power among a plurality of AC powers into a first DC power. The first inverter converts the first DC power into second AC power. The transformer converts the second AC power into third AC power. The second converter converts the third AC power into second DC power. The second inverter converts the second DC power into fourth AC power. The first converter, the first inverter, and the second converter are composed of unipolar elements, and the second inverter is composed of a bipolar element.

(2) The power converter includes a first converter (13), a first inverter (14), a transformer (15), and a second converter (16). The first converter converts a first AC power among a plurality of AC powers into a first DC power. The first inverter converts the first DC power into second AC power. The transformer converts the second AC power into third AC power. The second converter converts the third AC power into second DC power. The first converter, the first inverter, the transformer, and the second converter constitute one converter group (10). The breakdown voltage when a plurality of the converter groups are connected in series is higher than the highest voltage among the plurality of AC powers.

(3) The power converter includes a first converter (13), a first inverter (14), a transformer (15), a second converter (16), a voltage detector (11), a control circuit ( 12). The first converter converts a first AC power of the plurality of AC powers into a first DC power in a railway vehicle that receives a plurality of AC powers from a plurality of AC power overhead lines. The first inverter converts the first DC power into second AC power. The transformer converts the second AC power into third AC power. The second converter converts the third AC power into second DC power. The voltage detector detects voltages of the plurality of AC powers input to the railway vehicle. The control circuit controls the first converter, the first inverter, and the second converter based on the voltage detected by the voltage detector. The first converter, the first inverter, the transformer, the second converter, the voltage detector, and the control circuit constitute one converter group (10). In the configuration in which a plurality of the converter groups are connected in series, the power converter includes a plurality of converter groups connected in series and a plurality of short-circuit circuits (40) that short-circuit each of the plurality of converter groups. Have. The plurality of AC powers include a first voltage AC power and a second voltage AC power lower than the first voltage. When the AC power having the second voltage is input, the power converter performs a power conversion operation using a part of the plurality of converter groups.

Hereinafter, an embodiment based on the outline of the above-described embodiment will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.
[One Embodiment]

A power converter and a railway vehicle using the same according to the present embodiment will be described with reference to FIGS.
<Railway vehicles using power converters>

First, a railway vehicle using the power converter according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing an example of the configuration of a railway vehicle using this power converter. FIG. 1 shows a power converter including a multi-series converter circuit of a railway vehicle for an AC / DC overhead line.

The power converter 1 is used for a railway vehicle that receives a plurality of AC powers from a plurality of AC power overhead lines 2. Here, as a plurality of AC powers from a plurality of AC power overhead lines 2, for example, a single phase (1φ), AC 15 kV, AC 25 kV will be described. Moreover, in this Embodiment, the input of several DC power from the several DC power overhead line 3 is also possible, and the example of DC3kV and DC1.5kV is demonstrated here, for example.

The power converter 1 includes a voltage detector (VDT) 11, a control circuit (CTL) 12, a first converter (AC / DC) 13, a first inverter (DC / AC) 14, a transformer (MFT) 15, and A plurality of converter groups 10 each including a second converter (AC / DC) 16 are included. Here, for example, an example having 15 sets of converter groups 10 is illustrated. As will be described later, of the 15

converter groups

10, 14 converter groups are for regular use, and the remaining 1 set of converter groups is for redundancy. In the normal converter group, when 14 converter groups are driven, AC 25 kV can be handled, and when 8 converter groups are driven, AC 15 kV can be handled.

AC power is supplied to a plurality of converter groups 10 from a plurality of AC power overhead lines 2 through a pantograph 4 that is a current collector of a railway vehicle. Further, DC power is also supplied from a plurality of DC power overhead lines 3 through a pantograph 4 which is a current collector for a railway vehicle. For this purpose, a changeover switch 5 is connected between the pantograph 4 and the plurality of converter groups 10. The changeover switch 5 has a common terminal COM connected to the pantograph 4, an AC power terminal AC connected to an input node of the first stage converter group of the plurality of converter groups 10, and a DC power terminal DC The plurality of converter groups 10 are connected to the shorted output node. For example, when supplying AC power from the AC power overhead line 2, the changeover switch 5 is switched to the AC power terminal AC, and when supplying DC power from the DC power overhead line 3, the changeover switch 5 is It is switched to the DC power terminal DC side. The changeover switch 5 is changed over according to an instruction from, for example, a railway vehicle driver.

In each converter group 10, the voltage detector 11 is a voltage detector that detects a plurality of AC power voltages (AC 15 kV, AC 25 kV) input to the railway vehicle.

The control circuit 12 is a control circuit that controls the first converter 13, the first inverter 14, and the second converter 16 that constitute the converter group 10 based on the voltage detected by the voltage detector 11. The control circuit 12 also controls a short circuit 40 (described later) connected to each converter group 10.

The first converter 13 is a converter that converts the first AC power among the plurality of AC powers from the plurality of AC power overhead lines 2 to the first DC power.

The first inverter 14 is an inverter that converts the first DC power converted by the first converter 13 into second AC power.

The transformer 15 is a transformer that converts the second AC power converted by the first inverter 14 into third AC power.

The second converter 16 is a converter that converts the third AC power converted by the transformer 15 into second DC power.

The plurality of converter groups 10 are connected in series. A plurality of AC powers from a plurality of AC power overhead lines 2 are supplied to a first converter group of the plurality of converter groups 10 from a pantograph 4 that is a current collector of a railway vehicle via a changeover switch 5. The Moreover, the last converter group of the plurality of converter groups 10 is connected to the ground potential from the wheel 6 of the railway vehicle through the rail.

Also, the output nodes of the plurality of converter groups 10 are short-circuited, and the short-circuited nodes are connected to the input side of the second inverter (DC / AC) 21 for driving the motor. The second inverter 21 is an inverter that converts second DC power from a short-circuited node of the plurality of converter groups 10 into fourth AC power. Here, as the second DC power input to the second inverter 21, for example, an example of DC 3 kV is shown. A motor (M3) 7 for driving the railway vehicle is connected to the output side of the second inverter 21. The motor 7 is driven by AC power output from the second inverter 21. Here, the motor 7 shows an example of a three-phase motor driven by, for example, three-phase (3φ) AC power.

The short-circuited nodes of the plurality of converter groups 10 are also connected to the input side of the power supply inverter group. The power supply inverter group includes a third inverter (DC / AC) 31, a transformer 32, a third converter (AC / DC) 33, and a fourth inverter (DC / AC) 34.

The third inverter 31 is an inverter that converts the second DC power from the short-circuited node of the plurality of converter groups 10 into the fifth AC power.

The transformer 32 is a transformer that converts the fifth AC power converted by the third inverter 31 into the sixth AC power.

The third converter 33 is a converter that converts the sixth AC power converted by the transformer 32 into the fourth DC power.

The fourth inverter 34 is an inverter that converts the fourth DC power converted by the third converter 33 into seventh AC power.

The load device 8 is connected to the output side of the fourth inverter 34. The load device 8 is, for example, an air conditioner, an air conditioner, or other devices installed in a railway vehicle. Here, an example is shown in which the load device 8 is driven by, for example, AC 440V.
<Converter group and short circuit constituting power converter>

Referring to FIG. 2, the converter group and the short circuit constituting the power converter in the above-described railway vehicle of FIG. 1 will be described. FIG. 2 is a circuit diagram showing an example of a configuration of a converter group and a short circuit constituting the power converter. In FIG. 2, the converter group and short circuit which comprise a multi-serial converter are shown.

The power converter includes a plurality of converter groups 10 and a plurality of short circuits 40 that short-circuit each of the plurality of converter groups 10. Each of the plurality of converter groups 10 includes the first converter 13, the first inverter 14, the transformer 15, and the second converter 16 illustrated in FIG. 1. In FIG. 2, the voltage detector 11 and the control circuit 12 are omitted. Further, the change-over switch 5 is also omitted. When the change-over switch 5 is switched to the AC power terminal AC and AC power from the AC power overhead line 2 is supplied through the pantograph 4 (1φ, AC15 kV, AC25 kV). Indicates the state. In addition, each of the plurality of short-circuit circuits 40 is included in the control circuit 12 illustrated in FIG. Alternatively, each short circuit 40 can be included in each converter group 10 or provided individually.

In each converter group 10, the first converter 13 includes four semiconductor switch elements SW11 to SW14 and four semiconductor diode elements D11 to D14 that form a bridge circuit. Each of the semiconductor diode elements D11 to D14 is connected between the drain terminal and the source terminal of each of the semiconductor switch elements SW11 to SW14 so as to be in the forward direction from the source terminal to the drain terminal. Similar to the first converter 13, the first inverter 14 includes four semiconductor switch elements SW21 to SW24 and four semiconductor diode elements D21 to D24 that form a bridge circuit.

Between the first converter 13 and the first inverter 14, between the connection node between the semiconductor switch elements SW11 and SW12 of the first converter 13 and the connection node between the semiconductor switch elements SW21 and SW22 of the first inverter 14, A connection node between the semiconductor switch elements SW13 and SW14 of the first converter 13 and a connection node between the semiconductor switch elements SW23 and SW24 of the first inverter 14 are respectively connected. The connection node between the semiconductor switch elements SW14 and SW11 and the connection node between the semiconductor switch elements SW12 and SW13 of the first converter 13 are connected to the short circuit 40. The connection node between the semiconductor switch elements SW24 and SW21 and the connection node between the semiconductor switch elements SW22 and SW23 of the first inverter 14 are connected to the primary side (input side) of the transformer 15.

As with the first converter 13, the second converter 16 includes four semiconductor switch elements SW31 to SW34 and four semiconductor diode elements D31 to D34 that form a bridge circuit. The connection node between the semiconductor switch elements SW34 and SW31 and the connection node between the semiconductor switch elements SW32 and SW33 of the second converter 16 are connected to the secondary side (output side) of the transformer 15. The connection node between the semiconductor switch elements SW31 and SW32 of the second converter 16 and the connection node between the semiconductor switch elements SW33 and SW34 are connected at the output node of the second converter 16 of each converter group 10.

Each short circuit 40 includes two semiconductor switch elements SW41 to SW42 and two semiconductor diode elements D41 to D42. Each of the semiconductor diode elements D41 to D42 is connected between the drain terminal and the source terminal of each of the semiconductor switch elements SW41 to SW42 so as to be in the forward direction from the source terminal to the drain terminal. The source terminal of the semiconductor switch element SW41 and the source terminal of the semiconductor switch element SW42 are connected, and the drain terminal of the semiconductor switch element SW41 is connected to the semiconductor switch elements SW14 and SW11 of the first converter 13 of each converter group 10. Connected to the connection node, the drain terminal of the semiconductor switch element SW42 is connected to a connection node between the semiconductor switch elements SW12 and SW13 of the first converter 13 of each converter group 10.

The connection node between the semiconductor switch elements SW14 and SW11 of the first converter 13 of each converter group 10 is the pantograph 4 (only the first stage) or the semiconductor switch element SW12 of the first converter 13 of the converter group 10 connected in the previous stage. Are connected to the connection node of SW13. Further, the connection node between the semiconductor switch elements SW12 and SW13 of the first converter 13 of each converter group 10 is the connection node or ground of the semiconductor switch elements SW14 and SW11 of the first converter 13 of the converter group 10 connected at the subsequent stage. It is connected to the potential (only the last stage).

The plurality of converter groups 10 include at least one redundant converter group. In FIG. 2, one of 15 sets of converter groups 10 is a redundant converter group 10-R, and the other 14 groups are normal converter groups 10-1 to 10-14. Correspondingly, the plurality of short-circuit circuits 40 respectively connected to the plurality of converter groups 10 are also one set of redundancy short-circuit circuits 40-R, and the other 14 groups are regular short-circuit circuits 40-1 to 40-R. 40-14. In the 14 pairs of normal converter groups 10-1 to 10-14, when 14 pairs of normal converter groups are driven, AC 25 kV can be handled, and 8 pairs of normal converter groups are driven. In this case, AC 15 kV can be handled.

Redundant converter group 10-R is a first converter group when an operation failure occurs in one of the 14 pairs of normal converter groups 10-1 to 10-14. The short circuit 40 connected to is activated to bypass the first converter group, and the redundant converter group performs power conversion operation instead of the first converter group.

Further, the short circuit 40-R connected to the redundant converter group 10-R may be multiplexed. In the example of FIG. 2, an example is shown in which two short circuit circuits 40-R are connected in parallel to the redundant converter group 10-R and are duplicated.

The semiconductor switch elements constituting the first converter 13, the first inverter 14, and the second converter 16 included in each of the plurality of converter groups 10 are gate-controlled by the control circuit 12. The first converter 13 receives AC power input from the pantograph 4 (first stage only) or the converter group 10 connected in the previous stage by turning on / off the semiconductor switch elements SW11 to SW14 by gate control by the control circuit 12. Convert to DC power. The first inverter 14 converts the DC power input from the first converter 13 into AC power by turning on / off the semiconductor switch elements SW21 to SW24 by gate control by the control circuit 12. The AC power converted by the first inverter 14 becomes an input to the primary side of the transformer 15. The transformer 15 converts AC power input to the primary side into desired AC power and outputs it from the secondary side. The second converter 16 converts the AC power input from the secondary side of the transformer 15 into DC power by turning on / off the semiconductor switch elements SW31 to SW34 by gate control by the control circuit 12.

The semiconductor switch elements SW41 to SW42 constituting each of the plurality of short-circuit circuits 40 are also gate-controlled by the control circuit 12. When the short circuit 40 is activated, the semiconductor switch element SW41 is turned on and the semiconductor switch element SW42 is turned off by gate control by the control circuit 12, so that the current flows through the semiconductor switch element SW41 and the semiconductor diode element D42. The flow and the short circuit 40 are made to flow. At this time, the converter group 10 connected to the short circuit 40 becomes non-conductive, and the converter group 10 is bypassed. Further, when the short circuit 40 is deactivated, the semiconductor switch elements SW41 and SW42 are turned off by gate control by the control circuit 12, thereby making the short circuit 40 non-conductive. At this time, the converter group 10 connected to the short circuit 40 becomes a flow, and the converter group 10 performs a power conversion operation.

3 and 4, the converter group and the short-circuit circuit when different overhead line voltages are input in the power converter of FIG. 2 described above will be described. FIGS. 3A, 3B, and 3C are explanatory diagrams illustrating an example of operations of the converter group and the short circuit when the different overhead line voltages are input. 4A and 4B are explanatory diagrams showing an example of the appearance of a module that houses a converter group and a short circuit corresponding to the operation of FIG.

In the plurality of converter groups 10, as described with reference to FIG. 2, one set is a redundant converter group 10-R, and the other 14 groups are regular converter groups 10-1 to 10-14. Correspondingly, the plurality of short circuits 40 are also one set of redundant short circuits 40-R and the other 14 sets are regular short circuits 40-1 to 40-14. Here, out of the 15 converter groups 10, when 14 converter groups are driven, 1φ and AC 25 kV can be handled, and when 8 converter groups are driven, 1φ, AC 15 kV can be supported. In this configuration, the withstand voltage when a plurality of converter groups 10 are connected in series is higher than the highest voltage of the plurality of AC power from the plurality of AC power overhead wires 2. For example, the withstand voltage when 14 sets of converter groups are connected in series is higher than AC25 kV, and the withstand voltage when 8 sets of converter groups are connected in series is higher than AC15 kV.

3A shows a case where 14 converter groups are driven, and FIGS. 3B and 3C show a case where 8 converter groups are driven. In FIG. 3, circles indicated by broken lines indicate the short circuit 40, the first converter 13, the first inverter 14, and the second converter 16, respectively. Further, in the circles indicated by broken lines, the white background indicates a current-flowing state in which a current flows in the corresponding circuit and the dot notation indicates a non-current state in which the current does not flow through the corresponding circuit. For example, when the first converter 13, the first inverter 14, and the second converter 16 of a certain converter group 10 are in a conduction state, the short circuit 40 connected thereto is in a non-conduction state. Conversely, when the first converter 13, the first inverter 14, and the second converter 16 of a certain converter group 10 are in a non-current state, the short circuit 40 connected to the first converter 13, the first inverter 14, and the second converter 16 is in a current state. The transducer group is bypassed.

For example, as shown in FIG. 3A, when AC power on the high voltage overhead line side such as 1φ and AC 25 kV is input to a plurality of AC power overhead lines 2, a part of 14 of 15 converter groups 10 A power conversion operation is performed using a pair of converter groups 10-1 to 10-14. In this case, the other set is a redundant converter group 10-R. Here, the eighth converter group is the redundancy converter group 10-R. The eighth set indicates the eighth from the upper side in FIG. 3, and similarly, the n (n = 1 to 15) set indicates the nth from the upper side in FIG.

In this configuration, the first to seventh converter groups 10-1 to 10-7 performing power conversion operation are connected in series, bypassing the eighth redundant converter group 10-R, The ninth to fifteenth converter groups 10-8 to 10-14 that perform power conversion operation are connected in series. The eighth redundant converter group 10-R becomes a converter group that activates the short circuit 40-R connected to the redundant converter group and does not perform the power conversion operation. In this connection state, the current when AC 25 kV AC power is input is supplied to the first to seventh converter groups 10-1 to 10-7 and the eighth redundant converter group 10-R. It flows to the ground potential through the connected short circuit 40-R, the 9th to 15th converter groups 10-8 to 10-14.

If there is no defect in the first to seventh converter groups 10-1 to 10-7 and the ninth to fifteenth converter groups 10-8 to 10-14, the redundant conversion The short circuit 40-R connected to the device group 10-R is activated (flowed), and the redundant converter group 10-R is bypassed. If any of the first to seventh converter groups 10-1 to 10-7 and the ninth to fifteenth converter groups 10-8 to 10-14 (for example, the converter group 10-5). ) Is inactivated, the short circuit 40-R connected to the redundant converter group 10-R is deactivated instead of the converter group (for example, the converter group 10-5) in which this defect has occurred. The redundant converter group 10-R is subjected to a power conversion operation.

For example, as shown in FIG. 3 (b), when the AC power on the low voltage overhead line side such as 1φ and AC15 kV is input to the plurality of AC power overhead lines 2, 8 of some 15 sets of the converter group 10 A power conversion operation is performed using the converter groups 10-1, 10-3, 10-5, 10-7, 10-8, 10-10, 10-12, and 10-14. In this case, the other set is the redundant converter group 10-R, and the remaining six sets are the converter groups 10-2, 10-4, 10-6, 10-9, 10- 11, 10-13.

In this configuration, the first, third, fifth, seventh, ninth, eleventh, thirteenth, thirteenth, and fifteenth converter groups 10-1 and 10-3 performing power conversion operation. , 10-5, 10-7, 10-8, 10-10, 10-12, 10-14, and the second set, the fourth set, the sixth set, and the eighth set that activate the short circuit and do not operate the power conversion operation The first, tenth, twelfth, and fourteenth transducer groups 10-2, 10-4, 10-6, 10-R, 10-9, 10-11, and 10-13 are alternately connected in series. Connected. In this connection state, the current when AC 15 kV AC power is input is the short circuit 40-2, 3 connected to the first set of converter group 10-1 and the second set of converter group 10-2. Short circuit 40-4 connected to the fourth converter group 10-3, the fourth converter group 10-4,..., The seventh converter group 10-7, the eighth redundant conversion Short circuit 40-R connected to the device group 10-R, 9th converter group 10-8,..., 15 short circuit 40-13, 15 sets connected to the 14th converter group 10-13 It flows to the ground potential through the eye transducer group 10-14.

1st group, 3rd group, 5th group, 7th group, 9th group, 11th group, 13th group, 15th group of transducer groups 10-1, 10-3, 10-5, 10-7 , 10-8, 10-10, 10-12, 10-14, if there is no defect, 2nd, 4th, 6th, 8th, 10th, 12th, Activating (flowing) the short circuit connected to the 14th set of converters 10-2, 10-4, 10-6, 10-R, 10-9, 10-11, 10-13, Bypass each transducer group. If the first group, the third group, the fifth group, the seventh group, the ninth group, the eleventh group, the thirteenth group, and the fifteenth group of converters 10-1, 10-3, 10-5, 10 When a failure occurs in any one of −7, 10-8, 10-10, 10-12, and 10-14, instead of the converter group in which this failure has occurred, the eighth redundant converter group The short-circuit circuit 40-R connected to the 10-R is deactivated (non-energized), and the redundant converter group 10-R is operated for power conversion. Instead of the converter group in which a failure has occurred, the second group, the fourth group, the sixth group, the tenth group, the 12th group, 14th in addition to the eighth group of redundant converter groups 10-R. The converter groups 10-2, 10-4, 10-6, 10-9, 10-11, and 10-13 in the set can be subjected to power conversion operation.

Further, when AC power on the low voltage overhead line side such as 1φ and AC 15 kV is input, a configuration as shown in FIG. In this configuration, the first to seventh converter groups 10-1 to 10-7 that perform power conversion operation are connected in series, and the short-circuit circuit is activated and the power conversion operation is not performed. The converter groups 10-R and 10-8 to 10-13 are connected in series, and the 15th converter group 10-14 that performs power conversion operation is connected. In this connection state, when the AC power of 15 kV AC is input, currents from the first group to the seventh group of converter groups 10-1 to 10-7 and the eighth group to the 14th group of converter groups 10- The electric current flows to the ground potential through the short-circuit circuits 40-R, 40-8 to 40-13 connected to R, 10-8 to 10-13, and the 15th converter group 10-14.

If no defect occurs in the first to seventh and fifteenth converter groups 10-1 to 10-7 and 10-14, the eighth to fourteenth converter groups 10-R , 10-8 to 10-13 are activated (flowed) to bypass each converter group. If a failure occurs in any of the first to seventh and fifteenth converter groups 10-1 to 10-7, 10-14, instead of the converter group in which the defect has occurred, Then, the short-circuit circuit 40-R connected to the eighth redundant converter group 10-R is deactivated (non-energized), and the redundant converter group 10-R is subjected to power conversion operation. Instead of the converter group in which the failure has occurred, in addition to the eighth redundant converter group 10-R, the ninth to fourteenth converter groups 10-8 to 10-13 are subjected to power conversion. It is also possible to operate.

4, FIG. 4 (a) is a diagram showing an example of the appearance of a module that houses a converter group and a short circuit corresponding to the operation of FIG. 3 (b). That is, FIG. 4A shows the first group, the third group, the fifth group, the seventh group, the ninth group, the eleventh group, the thirteenth group, and the fifteenth group of converters 10- 1, 10-3, 10-5, 10-7, 10-8, 10-10, 10-12, 10-14, and the second set in which the short circuit is activated and the power conversion operation is not performed. Transformer groups 10-2, 10-4, 10-6, 10-R, 10-9, 10-11 of the group 6, the group 8, the group 8, the group 12, the group 14 The modules for storing 10-13 are arranged alternately.

FIG. 4B is a diagram showing an example of the appearance of a module that houses a converter group and a short circuit corresponding to the operation of FIG. That is, in FIG. 4B, modules that house the first to seventh converter groups 10-1 to 10-7 that perform power conversion operation are arranged side by side, and a short circuit is activated next to the modules. The eighth to fourteenth converter groups 10-R and 10-8 to 10-13 are arranged side by side, and the 15th converter group 10- 14 is arranged.

When the driving method shown in FIG. 3 (b) and the driving method shown in FIG. 3 (c) are compared, the driving method shown in FIG. Since the converter groups that are not allowed are grouped together, it is easy to control the operation by activation / deactivation. Further, when the module configuration shown in FIG. 4A is compared with the module configuration shown in FIG. 4B, the module configuration shown in FIG. 4A accommodates a converter group that performs power conversion operation. Since the modules that house the converter groups that are not to perform the power conversion operation are alternately arranged, heat generation due to the operation of the converter groups is also alternated, which is excellent in terms of heat dissipation.
<Semiconductor switch element and semiconductor diode element>

A semiconductor switch element and a semiconductor diode element used in the power converter shown in FIG. 2 will be described with reference to FIGS. 5 and 6 show examples of the structure of the semiconductor switch element, respectively, and FIGS. 7A, 7B, and 8A, 8B show examples of the structure of the semiconductor diode element, respectively.

The semiconductor switch element and the semiconductor diode element used for the power converter in the present embodiment are made of a silicon material or a compound material of silicon carbide (SiC) or gallium nitride (GaN). For example, the first converter 13, the first inverter 14, and the second converter 16, each short circuit 40 that short-circuits each converter group 10, the second inverter 21, which constitute each of the plurality of converter groups 10, Each semiconductor switch element and each semiconductor diode element such as the third inverter 31, the third converter 33, and the fourth inverter 34 are targeted. As an example, the semiconductor switch element is made of a silicon material, and the semiconductor diode element is made of a compound material. Alternatively, the semiconductor switch element and the semiconductor diode element are made of a compound material. Below, the structure of the semiconductor switch element and semiconductor diode element comprised from the compound material of SiC is demonstrated.

FIG. 5 is a cross-sectional view showing an example of the structure of a semiconductor switch element (SiC-MOS). The SiC-MOS is a semiconductor switch element SW of a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) made of a SiC compound material. FIG. 5 shows a so-called DMOS (Double Diffusion Metal Oxide Semiconductor) type SiC-MOS. In FIG. 5, SPm is a source electrode, GPm is a gate electrode, DRm is a drain electrode, SUB is a substrate, Tox is a gate insulating film, N ⁺ is a source layer, P is a base layer, and DFT is a drift layer.

In the SiC-DMOS shown in FIG. 5, the source layer N ^{+ serving} as the n ⁺ -type region connected to the source electrode SPm is connected to the drift layer DFT via a channel formed in the base layer P serving as the p-type region. Connected to. The drift layer DFT is, for example, an n ⁻ type region, and plays a role of securing a breakdown voltage. The substrate SUB is, for example, an n ⁺ type region, and the drain electrode DRm is connected to the substrate SUB. Although not shown, each of the source electrode SPm, the gate electrode GPm, and the drain electrode DRm is connected to each electrode pad using a metal wiring layer. In the case of SiC-DMOS, there is an advantage that the element structure is simple and the manufacturing cost can be reduced as compared with a trench structure type SiC-MOS. Therefore, a low-cost and low-loss power converter can be realized.

FIG. 6 is a cross-sectional view showing an example of the structure of a semiconductor switch element (SiC-IGBT). The SiC-IGBT is an IGBT (Insulated Gate Bipolar Transistor) semiconductor switch element SW made of a SiC compound material. The SiC-IGBT in FIG. 6 is different from the SiC-MOS in that a high concentration P ⁺ layer and a buffer layer N ⁺ Buf exist between the drift layer DFT and the substrate SUB. The presence of the high-concentration P ⁺ layer causes a conductivity modulation phenomenon and dramatically reduces the on-resistance. In addition, the switching loss of the element can be reduced by applying the buffer layer N ⁺ Buf as necessary. As described above, the SiC-IGBT structure is more complex than the SiC-MOS structure and requires more cost to form an element. However, when used for a converter for a railway vehicle that requires a large current, Since the switch loss can be reduced, there is an advantage that the loss of the converter can be reduced.

7A and 7B are diagrams showing an example of the structure of the semiconductor diode element (SiC-SBD), where FIG. 7A is a plan view and FIG. 7B is a cross-sectional view taken along the line A-A ′ in FIG. SiC-SBD is a semiconductor diode element of a Schottky barrier diode composed of a SiC compound material. The structure of the Schottky barrier diode D shown in FIG. 7 is a JTE (Junction Termination Extension) structure. In FIG. 7, AP is an anode electrode pad, SUB is a substrate, DFTd is a drift layer, ACTd is an active region, TMd is a termination region, CHSTPd is a channel stop region, IL3 is a passivation film, Cathode is a back electrode, IL1 is a surface electrode, IL2 is an electrode connected to the channel stop region CHSTPd.

FIG. 7 shows an n ⁻ type drift layer DFTd on an n ⁺ type substrate SUBd, and p ⁺ type guard ring regions p ⁺ , p type regions p and n ⁺ type channel stop regions formed on the upper surface of the n ⁻ type drift layer DFTd. Only the CHSTPd, the passivation film IL3, the back electrode Cathode, the front surface electrode IL1, and the electrode IL2 are shown, and the passivation film and the resin film formed above the illustration are omitted. In FIG. 7, the active region ACTd at the center of the semiconductor chip is illustrated as a so-called JBS (Junction Barrier Schottky) structure in which p ⁺ regions and n ⁻ regions are alternately arranged. The electric field tends to concentrate on the edge portion of the p ⁺ -type guard ring region, but the presence of the p-type JTE region p can alleviate the electric field concentration. As a result, the breakdown voltage of the power device can be increased. That is, by using in combination with the power module according to the present embodiment, a more reliable power conversion system can be realized.

8A and 8B are diagrams showing an example of the structure of the semiconductor diode element (SiC-PND), where FIG. 8A is a plan view and FIG. 8B is a cross-sectional view taken along the line AA ′ in FIG. The SiC-PND is a PN junction diode semiconductor diode element made of a SiC compound material. The PN junction diode D of FIG. 8 is different from the Schottky barrier diode of FIG. 7 in that a high concentration p ⁺ region is formed above the active region ACTd and forms a PN junction with n ^{− of the} drift layer DFTd. It is. Since a PN junction exists in the active region ACTd, the conductivity modulation phenomenon occurs in this portion. For this reason, compared with the unipolar Schottky barrier diode shown in FIG. 7, the on-resistance can be lowered even when a large current flows. Therefore, by using a SiC-IGBT and a SiC-PND in combination with a converter for a railway vehicle, it is possible to reduce the loss of the converter.
<Converter group constituting power converter and final stage inverter>

Referring to FIG. 9, the converter group and the final stage inverter constituting the power converter in the above-described railway vehicle of FIG. 1 will be described. FIG. 9 is a circuit diagram showing an example of a configuration of a converter group and a final stage inverter that constitute the power converter. FIG. 9 shows an example in which the converter group (converter group 10-1 is shown) and the semiconductor switch element and the semiconductor diode element of the final stage inverter are composed of a SiC compound material.

Each converter group 10 which comprises a power converter contains the 1st converter 13, the 1st inverter 14, the transformer 15, and the 2nd converter 16, as demonstrated in FIG. The first converter 13 is composed of semiconductor switch elements SW11 to SW14 and semiconductor diode elements D11 to D14. The semiconductor switch elements SW11 to SW14 are composed of SiC-MOS, and the semiconductor diode elements D11 to D14 are composed of SiC-SBD. The Similarly, in the first inverter 14 and the second converter 16, the semiconductor switch elements SW21 to SW24 and SW31 to SW34 are composed of SiC-MOS, and the semiconductor diode elements D21 to D24 and D31 to D34 are composed of SiC-SBD. Although not shown in FIG. 9, each short circuit 40 for short-circuiting each converter group 10 shown in FIG. 2 is also configured by the semiconductor switch elements SW41 to SW42 being made of SiC-MOS, and the semiconductor diode elements D41 to D40. D42 is composed of SiC-SBD.

On the other hand, the second inverter 21 which is the final stage inverter connected to the shorted node of the output node of each converter group 10 is composed of semiconductor switch elements SW51 to SW56 and semiconductor diode elements D51 to D56. The semiconductor switch elements SW51 to SW56 are composed of SiC-IGBT, and the semiconductor diode elements D51 to D56 are composed of SiC-PND. The semiconductor switch elements SW51 to SW56 and the semiconductor diode elements D51 to D56 of the second inverter 21 are preferably made of a compound material, but can also be made of a silicon material.

As described above, in the power converter shown in FIG. 9, the semiconductor switch elements of the converter group 10 are composed of wide band gap unipolar elements, and the semiconductor switch element of the second inverter 21 is composed of a wide band gap bipolar element. Composed. As power device materials, compound semiconductors such as SiC and GaN having a larger band gap than silicon are attracting attention. Since the compound semiconductor has a large band gap, the breakdown voltage is about 10 times that of silicon. For this reason, the compound device can be made thinner than the Si device, and the resistance value (Ron) during conduction can be greatly reduced. As a result, the so-called conduction loss (Ron × i ² ) represented by the product of the resistance value (Ron) and the conduction current (i) can be reduced, which can greatly contribute to power efficiency improvement. Paying attention to such features of high breakdown voltage and low loss, the power converter in the present embodiment uses a switch element and a diode element using a compound material.

Moreover, the device which uses a different kind of element by the semiconductor switch element of the converter group 10 and the semiconductor switch element of the 2nd inverter 21 is also performed. For example, by using a unipolar element as the semiconductor switch element of the converter group 10, the switch loss is small and an operation with a high frequency is possible. In addition, since the unipolar element has a high input impedance, it has an advantage that a weak voltage can be amplified with little noise and has a high withstand voltage. On the other hand, by using a bipolar element as the semiconductor switching element of the second inverter 21, it is possible to cope with a large current.
<Effect of Embodiment>

According to the power converter in the present embodiment described above and the railway vehicle using the power converter, for example, in a railway vehicle that receives a plurality of AC powers from a plurality of AC power overhead lines 2, the reliability can be improved. The power converter 1 that can be provided can be provided. More details are as follows.

(1) The first converter 13, the first inverter 14, and the second converter 16 are configured by unipolar elements, and the second inverter 21 is configured by a bipolar element, so that it corresponds to the characteristics of the elements. A suitable operation can be realized. For example, the switch loss utilizing the characteristics of the unipolar element is small, and it is possible to cope with a high current operation utilizing the characteristics of the bipolar element and the operation at high frequency.

(2) In a configuration in which a plurality of converter groups 10 including the first converter 13, the first inverter 14, the transformer 15, and the second converter 16 are connected in series, the output nodes of the plurality of converter groups 10 are short-circuited. The connected nodes are connected to the input side of the second inverter 21, so that the plurality of series converter groups 10 can be selectively operated even when the voltage of the AC power overhead line 2 is different.

(3) The first converter 13, the first inverter 14, the transformer 15, and the second converter 16 constitute one converter group 10, and a plurality of withstand voltages are obtained when the plurality of converter groups 10 are connected in series. It is possible to improve the reliability of the power converter 1 by selecting the converter group 10 to be activated according to the overhead voltage of the AC power overhead line 2 by being higher than the highest voltage of the AC power overhead line 2 of it can.

(4) Since the plurality of converter groups 10 include the redundant converter group 10-R, when an operation failure occurs in one converter group, the plurality of converter groups 10 are connected to the converter group in which the failure occurs. The short circuit 40 is activated to bypass this converter group, and instead the redundant converter group 10-R can perform a power conversion operation, so that the power converter 1 can perform a continuous power conversion operation.

(5) Since the short circuit 40-R connected to the redundancy converter group 10-R is multiplexed, the short circuit can be made redundant.

(6) When the AC power on the low voltage side of the plurality of AC power overhead lines 2 is input, by performing a power conversion operation using a part of the plurality of converter groups 10, The efficiency as the power converter 1 can be improved by selecting the converter group 10 to be activated according to the overhead line voltage and changing the number of operation of the plurality of converter groups 10.

(7) A part of the converter group 10 that performs the power conversion operation and the converter group 10 that activates the short circuit 40 and does not perform the power conversion operation are alternately connected in series, so that the heat generated by the operation of the converter group 10 Since generation | occurrence | production is also alternated, the power converter 1 excellent in the surface of heat dissipation is realizable.

(8) Each of the converter groups 10 that perform power conversion operation is connected in series, and each of the converter groups 10 that activates the short circuit 40 and does not perform power conversion operation is connected in series, thereby performing power conversion operation. Since the converter group 10 and the converter group 10 that does not perform the power conversion operation are gathered together, the power converter 1 that can easily control the operation by activation / deactivation can be realized.

(9) When no failure occurs in the plurality of converter groups 10, the short-circuit circuit 40-R connected to the redundant converter group 10-R is activated to bypass the redundant converter group 10-R. Thus, the redundant converter group 10-R can be made a converter group that does not perform the power conversion operation.

(10) The semiconductor switch element and the semiconductor diode element constituting the first converter 13, the first inverter 14, and the second converter 16 are made of a compound material of SiC or GaN. It is possible to increase the reliability of the power converter 1 by realizing high withstand voltage and low loss by utilizing the above, high efficiency and long life associated therewith.

(11) The first converter 13, the first inverter 14, the transformer 15, the second converter 16, the voltage detector 11, and the control circuit 12 constitute one converter group 10. Even in a configuration in which a plurality of units are connected in series, the same effects as the above (1) to (10) can be obtained.

As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

The above embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the configurations described. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.

For example, in the above-described embodiment, a power converter used for a railway vehicle has been described as an example. However, the present invention is not limited to this, and may be applied to a wind power generation system, a solar power generation system, or the like. Can do.

DESCRIPTION OF SYMBOLS 1 Power converter 2 AC power overhead line 3 DC power overhead line 4 Pantograph 5 Changeover switch 6 Wheel 7 Motor 8 Load apparatus 10 Converter group 11 Voltage detector 12 Control circuit 13 1st converter 14 1st inverter 15 Transformer 16 2nd converter 21 Second inverter 31 Third inverter 32 Transformer 33 Third converter 34 Fourth inverter 40 Short circuit

Claims

A first converter that converts a first AC power among a plurality of AC powers to a first DC power;
A first inverter that converts the first DC power into second AC power;
A transformer for converting the second AC power into third AC power;
A second converter for converting the third AC power into second DC power;
A second inverter for converting the second DC power into fourth AC power;
Have
The first converter, the first inverter, and the second converter are composed of unipolar elements,
The second inverter is a power converter composed of a bipolar element.
The power converter according to claim 1, wherein
In the configuration in which the first converter, the first inverter, the transformer, and the second converter constitute one converter group, and a plurality of the converter groups are connected in series.
An output node of the plurality of converter groups connected in series is short-circuited, and the short-circuited node is connected to an input side of the second inverter.
A first converter that converts a first AC power among a plurality of AC powers to a first DC power;
A first inverter that converts the first DC power into second AC power;
A transformer for converting the second AC power into third AC power;
A second converter for converting the third AC power into second DC power;
Have
The first converter, the first inverter, the transformer, and the second converter constitute one converter group,
A power converter, wherein a withstand voltage when a plurality of the converter groups are connected in series is higher than a maximum voltage among the plurality of AC powers.
The power converter according to claim 3, wherein
The power converter includes a plurality of converter groups connected in series, and a plurality of short circuits that short-circuit each of the plurality of converter groups.
The plurality of converter groups include at least one redundant converter group,
When a malfunction occurs in the first converter group of the plurality of converter groups, the short circuit connected to the first converter group is activated to bypass the first converter group. A power converter in which the redundant converter group performs a power conversion operation instead of the first converter group.
The power converter according to claim 4, wherein
The power converter, wherein the short circuit connected to the redundant converter group is multiplexed.
The power converter according to claim 4, wherein
A power converter that performs a power conversion operation using a part of the plurality of converter groups when the AC power on the low voltage side of the plurality of AC powers is input.
The power converter according to claim 6, wherein
A part of the converter group that performs the power conversion operation and the converter group that activates the short circuit and does not perform the power conversion operation are alternately connected in series.
The power converter according to claim 6, wherein
Each of a part of the converter groups that perform the power conversion operation is connected in series, and each of the converter groups that activates the short circuit and does not perform the power conversion operation is connected in series.
The power converter according to claim 6, wherein
A power converter that activates the short circuit connected to the redundant converter group and bypasses the redundant converter group when no defect has occurred in the plurality of converter groups.
The power converter according to claim 3, wherein
The first converter, the first inverter, and the second converter are composed of a semiconductor switch element and a semiconductor diode element,
The semiconductor switch element and the semiconductor diode element are power converters composed of a compound material of silicon carbide or gallium nitride.
In a railway vehicle that receives a plurality of AC power from a plurality of AC power overhead lines, a first converter that converts a first AC power of the plurality of AC powers to a first DC power;
A first inverter that converts the first DC power into second AC power;
A transformer for converting the second AC power into third AC power;
A second converter for converting the third AC power into second DC power;
A voltage detector for detecting the voltages of the plurality of AC powers input to the railway vehicle;
A control circuit for controlling the first converter, the first inverter, and the second converter based on the voltage detected by the voltage detector;
Have
The first converter, the first inverter, the transformer, the second converter, the voltage detector, and the control circuit constitute one converter group, and a plurality of the converter groups are connected in series. In
A plurality of converter groups connected in series, and a plurality of short circuits that short-circuit each of the plurality of converter groups,
The plurality of AC powers include a first voltage AC power and a second voltage AC power lower than the first voltage,
A power converter that performs power conversion operation using a part of the plurality of converter groups when AC power of the second voltage is input.
The power converter according to claim 11, wherein
A part of the converter group that performs the power conversion operation and the converter group that activates the short circuit and does not perform the power conversion operation are alternately connected in series.
The power converter according to claim 11, wherein
Each of a part of the converter groups that perform the power conversion operation is connected in series, and each of the converter groups that activates the short circuit and does not perform the power conversion operation is connected in series.
The power converter according to claim 11, wherein
The plurality of converter groups include at least one redundant converter group,
A power converter that activates the short circuit connected to the redundant converter group and bypasses the redundant converter group when no defect has occurred in the plurality of converter groups.
The power converter of claim 14.
When a failure occurs in the first converter group of the plurality of converter groups, the short circuit connected to the first converter group is activated to bypass the first converter group, A power converter in which a redundant converter group performs a power conversion operation instead of the first converter group.