GB2541966B

GB2541966B - Power converter and railway vehicle

Info

Publication number: GB2541966B
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: 2019-09-18
Anticipated expiration: 2036-04-19
Also published as: JP2016213945A; CN106130363B; JP6429720B2; GB2541966A; CN106130363A; DE102016207639A1

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 converterand in particular to the power converter including a 2-in-lsemiconductor switching element and a railway vehicle. 2. Description of the Related Art

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

Silicon (Si) is largely employed for a materialconstituting the semiconductor module. Application of awide gap semiconductor such as Silicon Carbide (SiC) andGallium Nitride (GaN) is studied so as to reduce furtherlosses. The SiC can speed up switching operation andreduce switching losses compared with the Si. A semiconductor switching element is preferablysmall-sized to compactly store the power converterincluding the plurality of semiconductor switching elementsin a housing and configure a stack. Techniques forreduction in size are known, in which a two-element- containing module (2-in-l semiconductor switching elementmodule) is provided in a form of one unit of a leg to beformed by connecting the two semiconductor switchingelements in series. JP-2006-42406-A relates to a stacked structure ofthe power converter including the two-element-containingmodule. Specifically, it is disclosed that the stackedstructure of the power converter includes a powersemiconductor element configured for more than one powersemiconductor elements to be connected in parallel per onephase of a power converter circuit performing polyphasealternating-current (AC) output or input, a radiator forcooling the power semiconductor elements, and a fan forcooling a radiator, and is characterized by being arrangedin parallel for each phase with respect to a ventilationdirection of the fan for cooling the radiator whenarranging the power semiconductor element on the radiator.

SUMMARY OF THE INVENTION

The stacked structure of the power converteraccording to JP-2006-42406-A which includes the two-element-containing module, enables reduction in size, andhowever, is insufficient to cool the semiconductorswitching element. Reasons for the above will be clarifiedin detail in an embodiment of the present invention. One reason thereof is that a longitudinal direction of themodule having a rectangular shape formed by forming thetwo-element-containing module and the ventilation directionof a cooling fin to be mounted on the stack are notoptimized.

Therefore, it is an object of the present inventionto provide a power converter including a small-sizedstacked structure with consideration given to improvementof cooling capability and a railway vehicle.

Accordingly, in the present invention, a powerconverter according to claim 1 is provided.

According to the present invention, it is possibleto provide a power converter including a small-sizedstacked structure with consideration given to improvementof cooling capability and a railway vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates positional relationships amongeach module of semiconductor modules, a heat receivingblock supporting and mounting the modules, and a coolingfin;

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

Fig. 3 is a perspective view illustrating connectionrelations among a capacitor, the semiconductor modules, andpositive and negative bus bars;

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

Fig. 5 illustrates a placement of a 2-in-l modulearranged on the heat receiving block and a positionalrelationship between electrodes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention is describedhereinafter with reference to the attached drawings.Embodiment A circuit configuration of a typical power converteris 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 QI to Q6. Fig. 2 illustrates an example of athree-phase circuit. Alternatively, a single-phase or apolyphase having three phases or more may be employed forthe circuit. Where the respective switching elements of QIand Q2, Q3 and Q4, and Q5 and Q6 use 2-in-l modules ofidentical modules, the power converter 5 includes asemiconductor module 108 with the switching elements QI andQ2, and a semiconductor module 109 with the switchingelements Q3 and Q4, and a semiconductor module 110 with theswitching elements Q5 and Q6.

The capacitors 102 and 103 may be any of anelectrolytic capacitor or a film capacitor, and may includemultiple small-capacity capacitor cells connected inparallel inside for larger capacity of the capacitors 102and 103. Where the switching elements QI to Q6 are IGBTs,diodes DI to D6 need to be arranged in opposite directionsto the IGBTs and to be each connected in parallel. Wherethe switching elements QI to Q6 are MOSFETs, a parasiticdiode of the MOSFET may be employed as the diodes DI to D6.Signs D, G, and S designate a drain electrode, a gateelectrode, and a source electrode of the switching elementQI, respectively.

The semiconductor module 108 includes the switchingelements QI and Q2 connected in series. A connecting pointof the switching element QI and Q2 forms an AC output point of a U-phase to a motor 311. Similarly, the semiconductormodule 109 includes the switching elements Q3 and Q4connected in series. A connecting point of the switchingelements Q3 and Q4 forms an AC output point of a V-phase tothe motor 311. The semiconductor module 110 includes theswitching elements Q5 and Q6 connected in series. Aconnecting point of the switching elements Q5 and Q6 formsan AC output point of a W-phase to the motor 311.

Wiring is used for electrical connection of thecapacitors 102 and 103 to the semiconductor modules 108,109, and 110. The wiring includes parasitic inductances104, 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 toreduce and equalize the parasitic inductances 104, 105, and106, a wiring portion of an electric circuit of Fig. 2 isconstituted of bus bars. For the specific bus barcomponents in the electric circuit of Fig. 2, the wiringbetween a positive electrode of the capacitors 102 and 103and a positive electrode of the semiconductor modules 108to 110 is a bus bar 201, and the wiring between a negativeelectrode of the capacitors 102 and 103 and a negativeelectrode of the semiconductor modules 108 to 110 is a busbar 202. It is preferred to include a bus bar 203 for eachphase between the connecting points of the switching elements in series of the semiconductor modules 108 to 110and the motor 311 as a load.

Fig. 3 is a perspective view illustrating connectionrelations among the capacitors 102 and 103, thesemiconductor modules 108 to 110, and the positive andnegative bus bars 201 and 202. The positive and negativebus 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. Thecapacitors 102 and 103 are arranged in an internal space ofthe two large and small U-shaped copper sheets 201 and 202.For example, positive and negative electrodes 301 and 302which are previously fixedly installed on the capacitors102 and 103 sides, are pressed onto the bus bars 201 and 202 between the positive and negative bus bars 201 and 202formed with two large and small U-shaped copper sheets andthe capacitors 102 and 103. Additionally, the electrodes301 and 302 are screwed from the bus bars 201 and 202 sidesto be electrically connected.

The capacitors 102 and 103 connect with the positiveand negative bus bars 201 and 202 through both sides ofplate portions of the U-shaped bus bars 201 and 202. Thesemiconductor modules 108 to 110 connect with the positiveand negative bus bars 201 and 202 through a bottom plateportion of the U-shaped copper sheets 201 and 202.

Although not illustrated accurately here, insulationbetween both bus bars is ensured when disposing thepositive bus bar 201 in the negative bus bar 202. Thenegative electrode 302 needs to pass through a hole portionopened in the positive bus bar 201 for connection to thenegative bus bar 202. Also in this case, the insulation isensured.

In Fig. 3, the connection relation between thesemiconductor modules 108 to 110 and the positive andnegative bus bars 201 and 202 is described hereinafter.The illustrated example indicates the case where thesemiconductor modules 108 to 110 each includes threemodules connected in parallel for higher currents. Asillustrated in Fig. 3, for example, positive and negativeelectrodes 401 and 402 which are previously fixedlyinstalled on each of the modules 108 to 110 sides, arepressed onto the bus bars 201 and 202 between the positiveand negative bus bars 201 and 202 formed with the two largeand small U-shaped copper sheets and each module of thesemiconductor modules 108 to 110 that include the threemodules connected in parallel for each phase. Additionally,the electrodes 401 and 402 are screwed from the bus bars201 and 202 sides to be electrically connected.

Fig. 1 illustrates positional relationships amongeach module of the semiconductor modules 108 to 110, a heat receiving block 7 supporting and mounting the modules, anda cooling fin 4. The heat receiving block 7 includes eachmodule of the semiconductor modules 108 to 110 (108a, 108b,108c, 109a, 109b, 109c, 110a, 110b, and 110c) and a gatedrive device G/D arranged on a first surface, and theplurality of cooling fins 4 arranged on a second surface.While no electrodes for connection between the respectivemodules and other portions are illustrated in Fig. 1, theconnection relation will be separately described withreference to Fig. 4.

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

The 2-in-l modules 109a, 109b, and 109c are connected to anAC V-phase. The 2-in-l modules 110a, 110b, and 110c areconnected 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 shapeand a longitudinal direction arranged in a verticaldirection 30 as illustrated. In contrast, a direction ofcooling air passing through the cooling fin 4 is a lateraldirection 40 as illustrated, which is perpendicular to thedirection 30. In Fig. 1, the semiconductor modules 108 to110 correspond to the U-phase, the V-phase, and the W-phase, respectively. Accordingly, directions of the modules byphase are also arranged in the longitudinal direction 30.

It is apparent from Fig. 1 that a length along thedirection in which the cooling air flows of a cooling unitis shorter than a length along the direction perpendicularto the cooling air.

The embodiment of the present invention ischaracterized in that the longitudinal direction of therectangular-shaped 2-in-l module is arranged in thedirection perpendicular to the direction of the cooling airpassing through the cooling fin 4. This is explained bythat: installation dimensions of the 2-in-l module in thedirection of the cooling air flow can be reduced bylongitudinal installation of the 2-in-l module;consequently, ventilation resistance between the coolingfins 4 can be reduced; the cooling air flows smoothlybetween the cooling fins 4 and this improves coolingefficiency; and therefore, the cooling fin 4 can be reducedin size.

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

That is, flooring of the railway vehicle is placed in anupper side of and a track is placed in an underside of, asillustrated in Fig. 4. The power converter 5 is mountedsuch that the cooling air 40 faces in a same direction as adirection of railway vehicle travelling. The semiconductormodules and the capacitors placed in the left side from theheat receiving block 7 are stored in a housing. Thecooling fin 4 placed in the right side from the heatreceiving block 7 is exposed in a space under the floor ofthe railway vehicle. The cooling air 40 generated duringtravelling of the railway vehicle passes between thecooling fins 4.

The positive and negative bus bars 201 and 202formed with two large and small U-shaped copper sheets arerepresented with U-shaped formation illustrated in Fig. 4.The U-shaped formation representing the positive bus bar201 is shown in the negative bus bar 202. The capacitors102 and 103 are vertically arranged in two places. Thecapacitors 102 and 103 are connected to the negative busbar 202 with the electrodes 302. Similarly, the capacitors102 and 103 are connected to the positive bus bar 201 withthe electrodes 301.

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

The two electrodes 401 and 402 out of the three electrodesare placed for connection to the positive and negative busbars 201 and 202. The third electrode is directed to thebus 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 memberformed in an L-shape, are commonly connected to therespective 2-in-l modules 108, 109, and 110 for each phasethrough the electrodes 403 in bending portions shown bydotted 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 thefilter capacitors 102 and 103 for smoothing are arrangedabove a projection surface of the heat receiving block 7 ofthe cooling unit, and terminals 301 and 302 of the filtercapacitors 102 and 103 are arranged on both sides of thedirection (vertical direction) perpendicular to thedirection in which the cooling air flows 40.

Fig. 5 illustrates a placement of the 2-in-l modulesarranged on the heat receiving block 7 and a positionalrelationship between the electrodes. Fig. 5 illustrates across-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 fromthe lowest to the highest places on the heat receivingblock 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 inparallel in a lateral direction, which is a travellingdirection of a railway vehicle, for higher currents. Andalso it is possible to apply to products requiring highercurrents by not having to increase the dimension in thevertical direction of an underfloor under severeconstraints .

In each module, the two circles in the uppermostplace denote the positive electrode 401, the two circles inthe next lower place denote the negative electrode 402, andthe two circles in the lowermost place denote the electrode403 that leads to an AC terminal. Fig. 5 illustrates thecross-section taken along the line A-A of Fig. 4.Accordingly, the bus bars 203U, 203V, and 203W for ACoutput (not illustrated in Fig. 5) are provided herein forconvenience as illustrated in the dotted lines.

In the left side position illustrated in Fig. 5, thegate drive devices G/D, which supplies positive andnegative firing signals to each semiconductor element ofthe 2-in-l module, are placed adjacent to eachsemiconductor element of the 2-in-l module constituting asingle phase. This configuration allows the firing signalto 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 asingle phase. The configuration also enables flexibleexpandability without consideration of such as mixedcontact with other portions even if the number of modulesincreases .

With Fig. 1, and Fig. 5 that clearly represent afeature of the present invention, the modules areconfigured to be longitudinally installed and to have thelongitudinal direction perpendicular to the ventilationdirection. Additionally, the respective phases constitutedof the 2-in-l switching elements are arranged in thedirection perpendicular to the cooling air. Therefore, inthe embodiment of the present invention, cross-sectionalstructures are consistent even if the number of parallelconnections of the modules increases, and easy designexpansion is provided.

Assuming that the stack is mounted in a vehicle, arail direction of a power unit may have an optimaldimension corresponding to control capacity of the motor311. For mounting in a vehicle, an upper portion of Fig. 5is to be fixedly mounted to be arranged in a lower portionof the vehicle. The higher control capacity yields largerbox longitudinal direction. The lower control capacityyields smaller box longitudinal direction.

Cooling can be efficiently performed for the reasonsdiscussed earlier compared with JP-2006-42406-A. The caseof supplying of electricity to a three-phase load isexemplified as above described, and however a single-phaseload may be applicable. Not only a two level but also athree level circuit configuration can be employed, and anyof an inverter or a converter may be applicable. Thecooling unit is not limited to a fin cooling. The coolingair is not limited to a vehicle-induced airflow and may begenerated by a fan.

With the embodiment of the present inventiondescribed above, the longitudinal direction of the modulebecomes perpendicular to the cooling air and accordingly aneffect of improvement in cooling capability can be obtainedby configuring the following power converter that: includesthe power converter circuit for switching between directcurrent and alternating current, the 2-in-l switchingelement constituting the power converter circuit, thecooling unit for cooling the 2-in-l switching element, thefilter capacitor for smoothing, and the gate drive devicefor transmitting a signal to the switching element; and ischaracterized in that the longitudinal direction of the 2-in-1 switching element is arranged facing the directionperpendicular to the cooling air and the plurality of phases constituted of the 2-in-l switching element arearranged in the direction perpendicular to the cooling air.

The gate drive device G/D is arranged in a positionadjacent to the 2-in-l element. This ensures that thesignal line from the gate drive device G/D to the modulecan be simplified so as to shorten a wiring length andfacilitate wiring without a tangle of wiring. The gatedrive device G/D can be arranged under the heightconstraint, enabling a contribution to the reduction insize .

The 2-in-l switching element is installed while thenumber of its parallel connections is changed based on thecontrol capacity. And the 2-in-l switching elementsconnected in parallel are installed so as to be eachaligned in the direction in which the cooling air flows.This also ensures that the signal line from the gate drivedevice G/D to the module can be simplified.

The filter capacitors for smoothing are arrangedabove the projection surface of the heat receiving block ofthe cooling unit. And the terminals of the filtercapacitors are arranged on both sides of the directionperpendicular to the direction in which the cooling airflows. Consequently, main circuit current flows in thevertical direction. A gate signal of the gate drive deviceG/D flows in the lateral direction. This provides no interference from one another and an effect such as noisenot readily being superposed on the gate signal. In theembodiment, the terminals of the filter capacitors arearranged on both sides of the direction perpendicular tothe direction in which the cooling air flows.

Alternatively, the terminals of the filter capacitors maybe arranged on one side of the direction perpendicular tothe direction in which the cooling air flows. Also in thisconfiguration, the main circuit current flows in thevertical direction. This provides an effect such as noisenot readily being superposed on the gate signal.

Same advantages are obtained also by theconfiguration that the filter capacitors for smoothing arearranged above the projection surface of the heat receivingblock of the cooling unit and the terminals of the filtercapacitors are arranged on one place for one side of thedirection perpendicular to the direction in which thecooling air flows.

Claims

Claims :

1. A power converter for a railway vehiclecomprising: a plurality of 2-in-l semiconductor modules, each ofthe 2-in-l semiconductor modules being one unit of a legformed by connecting two semiconductor switching elementsin series, and the 2-in-l semiconductor modulesconstituting one or more phases of a converter circuit suchthat the or each phase is constituted by more than one ofthe 2-in-l semiconductor modules; a heat receiving block comprising the plurality of 2-in-l semiconductor modules on a first surface; cooling fins on a second surface of the heatreceiving block; a filter capacitor electrically connected to theplurality of 2-in-l semiconductor modules by a bus bar; and a gate drive device configured to transmit a controlsignal to the plurality of switching elements, wherein a longitudinal direction of each 2-in-lsemiconductor module is arranged perpendicular to thedirection of cooling air passing between the cooling fins, wherein the gate drive device is arranged on thefirst surface in a position adjacent to the plurality of 2- in-1 semiconductor modules in the direction of the coolingair flow, wherein the filter capacitor for smoothing isarranged on a projection surface in a 2-in-l semiconductormodule side of the heat receiving block of a cooling unit,wherein the power converter, when used in a railwayvehicle, is mounted under a floor of the railway vehicle,wherein the cooling air generated during travellingof the railway vehicle passes between the cooling fins,wherein the heat receiving block is shorter in thedirection of the cooling air flow than in the directionperpendicular to the direction of the cooling air flow inthe plane of the surface of the heat receiving block, wherein the plurality of 2-in-l semiconductormodules are arranged in an array-like arrangement in thedirection of the cooling air flow and in the directionperpendicular to the direction of the cooling air flow onthe first surface of the heat receiving block, and wherein the 2-in-l semiconductor modulesconstituting the or each phase of the converter circuit areon a common air flow path, and are connected to the gatedrive device.

2. The power converter for a railway vehicleaccording to claim 1, wherein terminals of the filter capacitor arearranged on both sides of the filter capacitor in thedirection perpendicular to the direction of the cooling airflow.

3. The power converter for a railway vehicleaccording to claim 1, wherein terminals of the filter capacitor arearranged on one side of the filter capacitor in thedirection perpendicular to the direction of the cooling airflow.

4. A railway vehicle comprising the power converter according to any one of claims 1to 3 .