GB2541966A

GB2541966A - Power converter and railway vehicle

Info

Publication number: GB2541966A
Application number: GB1606818.1A
Authority: GB
Inventors: Yasuda Yosuke; Nakata Kiyoshi; Ishikawa Katsumi; Yamamoto Taku; Mae Kentarou; Tanaka Takeshi
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2015-05-07
Filing date: 2016-04-19
Publication date: 2017-03-08
Anticipated expiration: 2036-04-19
Also published as: CN106130363B; JP2016213945A; GB2541966B; CN106130363A; JP6429720B2; DE102016207639A1

Abstract

A power converter includes a plurality of semiconductor modules 110, a heat receiving block 7, a cooling fin 4, a filter capacitor (102, 103, figure 3), and a gate drive device. The semiconductor modules include a plurality of switching elements. The heat receiving block includes the plurality of semiconductor modules on a first surface and the cooling fin on a second surface. The filter capacitor is electrically connected to the semiconductor module. The gate drive device transmits a control signal to the switching element. A longitudinal direction of the semiconductor module is arranged facing a direction perpendicular to cooling air 40 passing between the cooling fins.

Description

TITLE OF THE INVENTION

POWER CONVERTER AND RAILWAY VEHICLE

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a power converter and in particular to the power converter including a 2-in-l semiconductor switching element and a railway vehicle. 2. Description of the Related Art

The power converter, typified by a recent inverter and converter, includes a semiconductor module with equipment such as an Insulated Gate Bipolar Transistor (IGBT) and a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) for reduction in losses.

Silicon (Si) is largely employed for a material constituting the semiconductor module. Application of a wide gap semiconductor such as Silicon Carbide (SiC) and Gallium Nitride (GaN) is studied so as to reduce further losses. The SiC can speed up switching operation and reduce switching losses compared with the Si. A semiconductor switching element is preferably small-sized to compactly store the power converter including the plurality of semiconductor switching elements in a housing and configure a stack. Techniques for reduction in size are known, in which a two-element-containing module (2-in-l semiconductor switching element module) is provided in a form of one unit of a leg to be formed by connecting the two semiconductor switching elements in series. JP-2006-42406-A relates to a stacked structure of the power converter including the two-element-containing module. Specifically, it is disclosed that the stacked structure of the power converter includes a power semiconductor element configured for more than one power semiconductor elements to be connected in parallel per one phase of a power converter circuit performing polyphase alternating-current (AC) output or input, a radiator for cooling the power semiconductor elements, and a fan for cooling a radiator, and is characterized by being arranged in parallel for each phase with respect to a ventilation direction of the fan for cooling the radiator when arranging the power semiconductor element on the radiator.

SUMMARY OF THE INVENTION

The stacked structure of the power converter according to JP-2006-42406-A which includes the two-element-containing module, enables reduction in size, and however, is insufficient to cool the semiconductor switching element. Reasons for the above will be clarified in detail in an embodiment of the present invention. One reason thereof is that a longitudinal direction of the module having a rectangular shape formed by forming the two-element-containing module and the ventilation direction of a cooling fin to be mounted on the stack are not optimized.

Therefore, it is an object of the present invention to provide a power converter including a small-sized stacked structure with consideration given to improvement of cooling capability and a railway vehicle.

Accordingly, in the present invention, a power converter includes: a plurality of semiconductor modules internally comprising a plurality of switching elements; a heat receiving block comprising the plurality of semiconductor modules on a first surface; a cooling fin on a second surface of the heat receiving block; a filter capacitor electrically connected to the semiconductor modules; and a gate drive device configured to transmit a control signal to the switching element, wherein a longitudinal direction of the semiconductor module is arranged facing a direction perpendicular to cooling air passing between the cooling fins.

According to the present invention, it is possible to provide a power converter including a small-sized stacked structure with consideration given to improvement of cooling capability and a railway vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates positional relationships among each module of semiconductor modules, a heat receiving block supporting and mounting the modules, and a cooling fin;

Fig. 2 illustrates a circuit configuration of a typical three-phase power converter;

Fig. 3 is a perspective view illustrating connection relations among a capacitor, the semiconductor modules, and positive and negative bus bars;

Fig. 4 illustrates a placement of and a connection relation between Fig. 1 and Fig. 3; and

Fig. 5 illustrates a placement of a 2-in-l module arranged on the heat receiving block and a positional relationship between electrodes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention is described hereinafter with reference to the attached drawings. Embodiment A circuit configuration of a typical power converter is described hereinafter with reference to Fig. 2.

In Fig. 2, a power converter 5 includes capacitors 102 and 103 smoothing a DC power supply 101 and switching elements Q1 to Q6. Fig. 2 illustrates an example of a three-phase circuit. Alternatively, a single-phase or a polyphase having three phases or more may be employed for the circuit. Where the respective switching elements of Q1 and Q2, Q3 and Q4, and Q5 and Q6 use 2-in-l modules of identical modules, the power converter 5 includes a semiconductor module 108 with the switching elements Q1 and Q2, and a semiconductor module 109 with the switching elements Q3 and Q4, and a semiconductor module 110 with the switching elements Q5 and Q6.

The capacitors 102 and 103 may be any of an electrolytic capacitor or a film capacitor, and may include multiple small-capacity capacitor cells connected in parallel inside for larger capacity of the capacitors 102 and 103. Where the switching elements Q1 to Q6 are IGBTs, diodes D1 to D6 need to be arranged in opposite directions to the IGBTs and to be each connected in parallel. Where the switching elements Q1 to Q6 are MOSFETs, a parasitic diode of the MOSFET may be employed as the diodes D1 to D6. Signs D, G, and S designate a drain electrode, a gate electrode, and a source electrode of the switching element Ql, respectively.

The semiconductor module 108 includes the switching elements Ql and Q2 connected in series. A connecting point of the switching element Ql and Q2 forms an AC output point of a U-phase to a motor 311. Similarly, the semiconductor module 109 includes the switching elements Q3 and Q4 connected in series. A connecting point of the switching elements Q3 and Q4 forms an AC output point of a V-phase to the motor 311. The semiconductor module 110 includes the switching elements Q5 and Q6 connected in series. A connecting point of the switching elements Q5 and Q6 forms an AC output point of a W-phase to the motor 311.

Wiring is used for electrical connection of the capacitors 102 and 103 to the semiconductor modules 108, 109, and 110. The wiring includes parasitic inductances 104, 105, and 106 that have values depending on a material, a length, and a shape of the wiring.

When a stacked structure is employed with intent to reduce and equalize the parasitic inductances 104, 105, and 106, a wiring portion of an electric circuit of Fig. 2 is constituted of bus bars. For the specific bus bar components in the electric circuit of Fig. 2, the wiring between a positive electrode of the capacitors 102 and 103 and a positive electrode of the semiconductor modules 108 to 110 is a bus bar 201, and the wiring between a negative electrode of the capacitors 102 and 103 and a negative electrode of the semiconductor modules 108 to 110 is a bus bar 202. It is preferred to include a bus bar 203 for each phase between the connecting points of the switching elements in series of the semiconductor modules 108 to 110 and the motor 311 as a load.

Fig. 3 is a perspective view illustrating connection relations among the capacitors 102 and 103, the semiconductor modules 108 to 110, and the positive and negative bus bars 201 and 202. The positive and negative bus bars 201 and 202 are formed with two large and small U-shaped copper sheets. For example, the positive bus bar 201 is arranged in the negative bus bar 202. The capacitors 102 and 103 are arranged in an internal space of the two large and small U-shaped copper sheets 201 and 202. For example, positive and negative electrodes 301 and 302 which are previously fixedly installed on the capacitors 102 and 103 sides, are pressed onto the bus bars 201 and 202 between the positive and negative bus bars 201 and 202 formed with two large and small U-shaped copper sheets and the capacitors 102 and 103. Additionally, the electrodes 301 and 302 are screwed from the bus bars 201 and 202 sides to be electrically connected.

The capacitors 102 and 103 connect with the positive and negative bus bars 201 and 202 through both sides of plate portions of the U-shaped bus bars 201 and 202. The semiconductor modules 108 to 110 connect with the positive and negative bus bars 201 and 202 through a bottom plate portion of the U-shaped copper sheets 201 and 202.

Although not illustrated accurately here, insulation between both bus bars is ensured when disposing the positive bus bar 201 in the negative bus bar 202. The negative electrode 302 needs to pass through a hole portion opened in the positive bus bar 201 for connection to the negative bus bar 202. Also in this case, the insulation is ensured.

In Fig. 3, the connection relation between the semiconductor modules 108 to 110 and the positive and negative bus bars 201 and 202 is described hereinafter.

The illustrated example indicates the case where the semiconductor modules 108 to 110 each includes three modules connected in parallel for higher currents. As illustrated in Fig. 3, for example, positive and negative electrodes 401 and 402 which are previously fixedly installed on each of the modules 108 to 110 sides, are pressed onto the bus bars 201 and 202 between the positive and negative bus bars 201 and 202 formed with the two large and small U-shaped copper sheets and each module of the semiconductor modules 108 to 110 that include the three modules connected in parallel for each phase. Additionally, the electrodes 401 and 402 are screwed from the bus bars 201 and 202 sides to be electrically connected.

Fig. 1 illustrates positional relationships among each module of the semiconductor modules 108 to 110, a heat receiving block 7 supporting and mounting the modules, and a cooling fin 4. The heat receiving block 7 includes each module of the semiconductor modules 108 to 110 (108a, 108b, 108c, 109a, 109b, 109c, 110a, 110b, and 110c) and a gate drive device G/D arranged on a first surface, and the plurality of cooling fins 4 arranged on a second surface. While no electrodes for connection between the respective modules and other portions are illustrated in Fig. 1, the connection relation will be separately described with reference to Fig. 4.

Fig. 1 illustrates the case where three modules are connected in parallel for higher currents. The 2-in-l modules 108a, 108b, and 108c are connected to an AC U-phase.

The 2-in-l modules 109a, 109b, and 109c are connected to an AC V-phase. The 2-in-l modules 110a, 110b, and 110c are connected to an AC W-phase.

As illustrated in Fig. 1, the 2-in-l modules (108a, 108b, 108c, 109a, 109b, 109c, 110a, 110b, and 110c) according to the present invention has a rectangular shape and a longitudinal direction arranged in a vertical direction 30 as illustrated. In contrast, a direction of cooling air passing through the cooling fin 4 is a lateral direction 40 as illustrated, which is perpendicular to the direction 30. In Fig. 1, the semiconductor modules 108 to 110 correspond to the U-phase, the V-phase, and the W-phase, respectively. Accordingly, directions of the modules by phase are also arranged in the longitudinal direction 30.

It is apparent from Fig. 1 that a length along the direction in which the cooling air flows of a cooling unit is shorter than a length along the direction perpendicular to the cooling air.

The embodiment of the present invention is characterized in that the longitudinal direction of the rectangular-shaped 2-in-l module is arranged in the direction perpendicular to the direction of the cooling air passing through the cooling fin 4. This is explained by that: installation dimensions of the 2-in-l module in the direction of the cooling air flow can be reduced by longitudinal installation of the 2-in-l module; consequently, ventilation resistance between the cooling fins 4 can be reduced; the cooling air flows smoothly between the cooling fins 4 and this improves cooling efficiency; and therefore, the cooling fin 4 can be reduced in size.

Fig. 4 illustrates a placement of and a connection relation between Fig. 1 and Fig. 3. The capacitor side of Fig. 3 is illustrated in a left side of Fig. 4. The cooling fin 4 side is illustrated in a right side of Fig. 4. Note that the power converter 5 is mounted under a floor of a railway vehicle in a direction illustrated in Fig. 4.

That is, flooring of the railway vehicle is placed in an upper side of and a track is placed in an underside of, as illustrated in Fig. 4. The power converter 5 is mounted such that the cooling air 40 faces in a same direction as a direction of railway vehicle travelling. The semiconductor modules and the capacitors placed in the left side from the heat receiving block 7 are stored in a housing. The cooling fin 4 placed in the right side from the heat receiving block 7 is exposed in a space under the floor of the railway vehicle. The cooling air 40 generated during travelling of the railway vehicle passes between the cooling fins 4.

The positive and negative bus bars 201 and 202 formed with two large and small U-shaped copper sheets are represented with U-shaped formation illustrated in Fig. 4. The U-shaped formation representing the positive bus bar 201 is shown in the negative bus bar 202. The capacitors 102 and 103 are vertically arranged in two places. The capacitors 102 and 103 are connected to the negative bus bar 202 with the electrodes 302. Similarly, the capacitors 102 and 103 are connected to the positive bus bar 201 with the electrodes 301.

The 2-in-l modules 108, 109, and 110 which are vertically arranged in three places, each includes the electrodes arranged toward the three types of bus bars.

The two electrodes 401 and 402 out of the three electrodes are placed for connection to the positive and negative bus bars 201 and 202. The third electrode is directed to the bus bar 203 for obtaining the AC output illustrated in Fig. 2. The three bus bars 203U, 203V, and 203W for the U, V, and W-phases of AC, which are made of a plate-shaped member formed in an L-shape, are commonly connected to the respective 2-in-l modules 108, 109, and 110 for each phase through the electrodes 403 in bending portions shown by dotted line (not illustrated). The bus bars 203U, 203V, and 203W are connected to the motor 311.

Fig. 4 viewed from the left side shows that the filter capacitors 102 and 103 for smoothing are arranged above a projection surface of the heat receiving block 7 of the cooling unit, and terminals 301 and 302 of the filter capacitors 102 and 103 are arranged on both sides of the direction (vertical direction) perpendicular to the direction in which the cooling air flows 40.

Fig. 5 illustrates a placement of the 2-in-l modules arranged on the heat receiving block 7 and a positional relationship between the electrodes. Fig. 5 illustrates a cross-section taken along the line A-A of Fig. 4. With Fig. 5, the U-phase, V-phase, and W-phase of AC are formed from the lowest to the highest places on the heat receiving block 7, and the three modules are connected in parallel for higher currents in each phase (each place). Therefore, it is preferred to increase the number of modules in parallel in a lateral direction, which is a travelling direction of a railway vehicle, for higher currents. And also it is possible to apply to products requiring higher currents by not having to increase the dimension in the vertical direction of an underfloor under severe constraints .

In each module, the two circles in the uppermost place denote the positive electrode 401, the two circles in the next lower place denote the negative electrode 402, and the two circles in the lowermost place denote the electrode 403 that leads to an AC terminal. Fig. 5 illustrates the cross-section taken along the line A-A of Fig. 4. Accordingly, the bus bars 203U, 203V, and 203W for AC output (not illustrated in Fig. 5) are provided herein for convenience as illustrated in the dotted lines.

In the left side position illustrated in Fig. 5, the gate drive devices G/D, which supplies positive and negative firing signals to each semiconductor element of the 2-in-l module, are placed adjacent to each semiconductor element of the 2-in-l module constituting a single phase. This configuration allows the firing signal to be collectively transmitted via signal lines 33U, 33V, and 33W from the lateral direction to the plurality of modules that are connected in parallel and constitutes a single phase. The configuration also enables flexible expandability without consideration of such as mixed contact with other portions even if the number of modules increases .

With Fig. 1, and Fig. 5 that clearly represent a feature of the present invention, the modules are configured to be longitudinally installed and to have the longitudinal direction perpendicular to the ventilation direction. Additionally, the respective phases constituted of the 2-in-l switching elements are arranged in the direction perpendicular to the cooling air. Therefore, in the embodiment of the present invention, cross-sectional structures are consistent even if the number of parallel connections of the modules increases, and easy design expansion is provided.

Assuming that the stack is mounted in a vehicle, a rail direction of a power unit may have an optimal dimension corresponding to control capacity of the motor 311. For mounting in a vehicle, an upper portion of Fig. 5 is to be fixedly mounted to be arranged in a lower portion of the vehicle. The higher control capacity yields larger box longitudinal direction. The lower control capacity yields smaller box longitudinal direction.

Cooling can be efficiently performed for the reasons discussed earlier compared with JP-2006-42406-A. The case of supplying of electricity to a three-phase load is exemplified as above described, and however a single-phase load may be applicable. Not only a two level but also a three level circuit configuration can be employed, and any of an inverter or a converter may be applicable. The cooling unit is not limited to a fin cooling. The cooling air is not limited to a vehicle-induced airflow and may be generated by a fan.

With the embodiment of the present invention described above, the longitudinal direction of the module becomes perpendicular to the cooling air and accordingly an effect of improvement in cooling capability can be obtained by configuring the following power converter that: includes the power converter circuit for switching between direct current and alternating current, the 2-in-l switching element constituting the power converter circuit, the cooling unit for cooling the 2-in-l switching element, the filter capacitor for smoothing, and the gate drive device for transmitting a signal to the switching element; and is characterized in that the longitudinal direction of the 2-in-1 switching element is arranged facing the direction perpendicular to the cooling air and the plurality of phases constituted of the 2-in-l switching element are arranged in the direction perpendicular to the cooling air.

The gate drive device G/D is arranged in a position adjacent to the 2-in-l element. This ensures that the signal line from the gate drive device G/D to the module can be simplified so as to shorten a wiring length and facilitate wiring without a tangle of wiring. The gate drive device G/D can be arranged under the height constraint, enabling a contribution to the reduction in size .

The 2-in-l switching element is installed while the number of its parallel connections is changed based on the control capacity. And the 2-in-l switching elements connected in parallel are installed so as to be each aligned in the direction in which the cooling air flows. This also ensures that the signal line from the gate drive device G/D to the module can be simplified.

The filter capacitors for smoothing are arranged above the projection surface of the heat receiving block of the cooling unit. And the terminals of the filter capacitors are arranged on both sides of the direction perpendicular to the direction in which the cooling air flows. Consequently, main circuit current flows in the vertical direction. A gate signal of the gate drive device G/D flows in the lateral direction. This provides no interference from one another and an effect such as noise not readily being superposed on the gate signal. In the embodiment, the terminals of the filter capacitors are arranged on both sides of the direction perpendicular to the direction in which the cooling air flows.

Alternatively, the terminals of the filter capacitors may be arranged on one side of the direction perpendicular to the direction in which the cooling air flows. Also in this configuration, the main circuit current flows in the vertical direction. This provides an effect such as noise not readily being superposed on the gate signal.

Same advantages are obtained also by the configuration that the filter capacitors for smoothing are arranged above the projection surface of the heat receiving block of the cooling unit and the terminals of the filter capacitors are arranged on one place for one side of the direction perpendicular to the direction in which the cooling air flows.

Claims

What is claimed is:

1. A power converter comprising: a plurality of semiconductor modules internally comprising a plurality of switching elements; a heat receiving block comprising the plurality of semiconductor modules on a first surface; a cooling fin on a second surface of the heat receiving block; a filter capacitor electrically connected to the semiconductor modules; and a gate drive device configured to transmit a control signal to the switching element, wherein a longitudinal direction of the semiconductor module is arranged facing a direction perpendicular to cooling air passing between the cooling fins .

2. The power converter according to claim 1, wherein the heat receiving block comprises a shorter length in the direction of cooling air flow than a length in the direction perpendicular to the direction of the cooling air flow.

3. The power converter according to claim 1 or 2, wherein the plurality of semiconductor modules are arranged in multiple places in the direction of the cooling air flow and in the direction perpendicular to the direction of the cooling air flow on the first surface of the heat receiving block, and wherein the plurality of semiconductor modules are connected to the common gate drive device and configured to constitute a single phase of a converter circuit, the semiconductor modules being arranged in the direction of the cooling air flow.

4. The power converter according to claim 3, wherein the gate drive device is arranged in a position adjacent to the semiconductor module in the direction of the cooling air flow.

5. The power converter according to claim 3 or 4, wherein a filter capacitor for smoothing is arranged on a projection surface in a semiconductor module side of the heat receiving block of a cooling unit, and wherein terminals of the filter capacitor are arranged on both sides of the direction perpendicular to the direction of the cooling air flow.

6. The power converter according to claim 3 or 4, wherein the filter capacitor for smoothing is arranged on the projection surface in the semiconductor module side of the heat receiving block of the cooling unit, and wherein the terminals of the filter capacitor are arranged on one side of the direction perpendicular to the direction of the cooling air flow.

7. A power converter comprising a heat receiving block, wherein the heat receiving block has a first surface in which a cooling air flows in a first direction, and the heat receiving block has a second surface in which a plurality of modules including a 2-in-l switching element constituting a power converter circuit are arranged, the power converter circuit switching between direct current and alternating current, and wherein the modules of each phase of polyphase alternating current are arranged in a second direction perpendicular to the first direction of the second surface of the heat receiving block, and each phase is constituted of a plurality of modules in parallel, the modules in parallel being arranged in the second direction, the modules comprising a longitudinal direction as the second direction.

8. The power converter according to claim 7, further comprising a gate drive circuit configured to supply a gate signal to the 2-in-l switching element constituting the power converter circuit, the gate drive circuit being arranged in an end portion in the second direction of the second surface of the heat receiving block.

9. A railway vehicle comprising the power converter according to any one of claim 1 to 8 .