TWI624138B - Stacked inverter - Google Patents

Abstract

A stacked inverter for converting direct current output from a direct current power source into alternating current for output to a motor, the stacked inverter comprising two power modules stacked one on top of the other, a current input conducting unit and a Current output conduction unit. Each power module includes an input electrode unit and an output electrode unit, and the output electrode unit is spaced apart from the input electrode unit. The current input conducting unit is electrically connected between the DC power source and the input electrode units of the power modules. A current output conducting unit is electrically connected between the output electrode units and the motor.

Description

Stacked inverter

The present invention relates to an inverter, and more particularly to a stacked inverter.

In general inverters for vehicles, an Insulated Gate Bipolar Transistor (IGBT) module is used to convert DC power into AC power for use in other electrical components, such as motors. However, when it is desired to increase the power that the inverter can output, it will be limited by the maximum current value that can be output by a single IGBT module, which cannot meet the market demand. The existing method is to parallel two sets of IGBT modules of the same specification, which can improve the output current and power of the inverter, but other problems arise, such as the water circuit structure for cooling the IGBT module will be complicated, parallel The difference in the resistance value of the circuit will make the input and output currents of the two sets of IGBT modules different, and the overall size of the inverter increases due to the parallel two sets of IGBT modules, which makes the difficulty of the internal component arrangement of the vehicle increase. Therefore, there are still many areas for improvement of existing inverters using IGBT modules.

Accordingly, it is an object of the present invention to provide a stacked inverter of high space utilization.

The stacked inverter of the present invention is used for converting direct current outputted from a direct current power source into alternating current for output to a motor. The stacked inverter includes two power modules stacked one on top of the other, each power module including an input. An electrode unit and an output electrode unit are spaced apart from the input electrode unit; a current input conducting unit electrically connected between the DC power source and the input electrode units of the power modules; and a current output conducting unit Electrically connected between the output electrode units and the motor.

In some implementations, the output electrode unit includes a first output electrode, a second output electrode, and a third output electrode. The positions of the first output electrodes of the two power modules correspond to the two power modes. The positions of the second output electrodes of the group correspond to the positions of the third output electrodes of the two power modules.

In some embodiments, each power module further includes a body having a first surface and a second surface opposite to the first surface, the output electrode unit and the input electrode unit being disposed on the first surface On one side, the second faces are opposite each other.

In some implementations, the connector further includes a connector disposed between the second faces of the power modules, and each power module further includes a heat sink disposed on the second surface.

In some implementations, the current output conducting unit includes a first bus bar electrically connected between the first output electrodes of each power module, and a second output electrically connected to each of the power modules. a second bus bar between the electrodes, and a third bus bar electrically connected between the third output electrodes of each of the power modules.

In some implementations, the first bus bar has a first connection segment electrically connected between the first output electrodes of each power module, and a first connection segment connected to the motor and electrically connected to the motor a first output segment, the first output segment is connected to the middle of the first connection segment, the second bus bar has a second connection segment electrically connected between the second output electrodes of each power module, and a second output section connected to the middle of the second connecting section and electrically connected to the motor, the third bus bar having a third connecting section electrically connected between the third output electrodes of each power module, and A third output section is connected to the third connecting section and electrically connected to the motor, and the third output section is connected to the middle of the third connecting section.

In some implementations, the first connecting segment has two first horizontal plate portions electrically connecting the first output electrodes of the power modules, and a first connecting portion between the two first horizontal plates. a first vertical plate portion, the first output segment is connected to the first vertical plate portion, the first output segment is respectively spaced apart from the two first horizontal plate portions by a distance, and the second connecting segment has two separate electrical segments a second horizontal plate portion connecting the second output electrodes of the power modules, and a second vertical plate portion connected between the two second horizontal plate portions, the second output portion being connected to the second vertical plate a second output section having the same distance from the two second horizontal sections, the third connection section having two third horizontal plates electrically connecting the third output electrodes of the power modules And a third vertical plate portion connected between the two third horizontal plate portions, the third output portion is connected to the third vertical plate portion, and the third output portion and the two third horizontal plate portions respectively The distances are the same.

In some implementations, the input electrode unit includes a first positive electrode, a first negative electrode, a second positive electrode, a second negative electrode, a third positive electrode, and a third negative electrode. The first positive electrode and the second negative electrode The positive electrode and the third positive electrode are spaced apart from each other, the first negative electrode, the second negative electrode and the third negative electrode are spaced apart from each other, the first positive electrode and the first negative electrode are adjacent to each other, and the second positive electrode and the second negative electrode are adjacent to each other Adjacent to each other, the third positive electrode and the third negative electrode are adjacent to each other, wherein the first positive electrode, the second positive electrode, and the third positive electrode of the input electrode unit of one power module are respectively connected to another power module The first negative electrode, the second negative electrode and the third negative electrode corresponding to each other, the current input conducting unit comprises a first positive bus bar electrically connected to the first positive electrode of each power module, and an electrical connection a first negative bus bar between the first negative electrodes of each power module, a second positive bus bar electrically connected between the second positive electrodes of each power module, and one electrically connected to each of the electric power a second between the second negative electrodes of the module a third bus bar, a third positive bus bar electrically connected between the third positive electrodes of each power module, and a third negative bus bar electrically connected between the third negative electrodes of the power modules, The first positive bus bar has a first positive connection portion electrically connected between the first positive electrodes of each power module, and a first positive input connected to the first positive connection portion and electrically connected to the DC power supply The first negative bus bar has a first negative connection portion electrically connected between the first negative electrodes of each power module, and a first connection to the first negative connection portion and electrically connected to the DC power supply a second positive electrode bus bar having a second positive electrode connecting portion electrically connected to the second positive electrode of each power module, and a second positive electrode connecting portion connected to the second positive electrode connecting portion and electrically connected to the DC power source a second positive input section, the second negative bus bar has a second negative connection section electrically connected between the second negative electrodes of the power modules, and a second negative connection section is connected and electrically connected to the DC Second negative input section of the power supply The third positive bus bar has a third positive connection portion electrically connected between the third positive electrodes of each power module, and a third positive input connected to the third positive connection portion and electrically connected to the DC power supply The third negative bus bar has a third negative connection portion electrically connected between the third negative electrodes of each power module, and a third connection connecting the third negative connection portion and electrically connecting the DC power supply Negative input section.

The present invention has at least the following effects: the power modules are stacked one on top of the other, and the DC input of the DC power input can be converted by the parallel connection of the current input conducting unit and the current output conducting unit. For the AC output to be used by the motor, not only the output power of the inverter is effectively improved, but the structure is more complicated and takes up a larger volume than the conventional parallel power module, and the invention has higher space utilization. Make the components in the car more flexible.

Referring to FIG. 1 and FIG. 2, an embodiment of the stacked inverter of the present invention is disposed in an electric vehicle (not shown) for converting direct current output from the direct current power source into alternating current to output to a motor (not shown). The DC power supply includes a film capacitor 20 having a first input positive electrode 201, a first input negative electrode 202, a second input positive electrode 203, a second input negative electrode 204, and a third input positive electrode 205. A third input negative electrode 206 includes a connection base 1, two power modules 2, a current input conduction unit 3, and a current output conduction unit 4.

Referring to FIG. 1 and FIG. 3, the connecting base 1 is substantially in the shape of a rectangular cylinder, and is provided with two openings 13 correspondingly up and down and extending in the longitudinal direction of the connecting seat 1 and having a square shape. The connecting base 1 also has an end portion. A water inlet 11 and a water outlet 12 at the opposite end of the water inlet 11 define a heat dissipation space S communicating with the water inlet 11, the water outlet 12 and the openings 13. The function of the connection seat 1 will be detailed later. .

Referring to FIG. 3 to FIG. 5 , the two power modules 2 are stacked on top of each other and are respectively disposed on the upper and lower sides of the connecting base 1 and corresponding to the openings 13 . Each power module 2 includes a body 21 and an input electrode. The unit 22, an output electrode unit 23 and a heat sink 24. The body 21 has a first surface 211 and a second surface 212 opposite to the first surface 211. The output electrode unit 23 and the input electrode unit 22 are disposed on the first surface 211, and the second surfaces 212 are opposite to each other. . The input electrode unit 22 is disposed on the first surface 211, and includes a first positive electrode 221, a first negative electrode 222, a second positive electrode 223, a second negative electrode 224, a third positive electrode 225, and a third negative electrode 226. The first positive electrode 221, the second positive electrode 223 and the third positive electrode 225 are spaced apart from each other, and the first negative electrode 222, the second negative electrode 224 and the third negative electrode 226 are spaced apart from each other, and the first positive electrode 221 and the first electrode The anodes 222 are adjacent to each other, the second cathodes 223 and the second anodes 224 are adjacent to each other, and the third cathodes 225 and the third anodes 226 are adjacent to each other, and the input electrode unit 22 of one of the power modules 2 The first positive electrode 221 , the second positive electrode 223 , and the third positive electrode 225 respectively correspond to the positions of the first negative electrode 222 , the second negative electrode 224 , and the third negative electrode 226 of the other power module 2 . The output electrode unit 23 is disposed on the first surface 211 and is located on the other side of the first surface 211 with respect to the input electrode unit 22, and includes a first output electrode 231, a second output electrode 232, and a third output electrode. 233, which represents the U, V, and W poles of the three-phase current, wherein the positions of the first output electrodes 231 of the two power modules 2 correspond to each other, and the second output electrodes 232 of the two power modules 2 The position of the third output electrode 233 of the two power modules 2 corresponds to the upper and lower positions. It should be noted that one of the power modules 2 is programmed through the interior thereof so that the two powers are The first output electrode 231, the second output electrode 232, and the third output electrode 233 of the module 2 are vertically connected. If not set, the first output electrode 231 of the two power modules 2 will be connected to the third output electrode. The 233 position corresponds to the upper and lower. The heat dissipating member 24 is disposed on the second surface 212 and extends into the heat dissipating space S of the connecting base 1 such that the heat dissipating members 24 of the two power modules 2 are opposite to each other, and the heat dissipating member 24 is in the embodiment of the plurality of heat dissipating columns. However, it is not limited to this, but it can also be other forms such as heat sink fins.

Referring to FIG. 3 and FIG. 6 , the current input and conduction unit 3 is electrically connected between the film capacitor 20 of the DC power source and the input electrode units 22 of the power modules 2 , and includes an electrical connection to each of the power modules 2 . The first positive bus bar 31 between the first positive electrode 221 and the first negative bus bar 32 electrically connected to the first negative electrode 222 of each power module 2 are electrically connected to each of the power modes. a second positive bus bar 33 between the second positive electrodes 223 of the group 2, a second negative current bus bar 34 electrically connected between the second negative electrodes 224 of each of the power modules 2, and one electrically connected to each a third positive bus bar 35 between the third positive electrode 225 of the power module 2 and a third negative bus bar 36 electrically connected between the third negative electrode 226 of each power module 2, the first positive electrode The bus bar 31 has a first positive connection portion 311 electrically connected to the first positive electrode 221 of each power module 2, and a first input connected to the first positive connection portion 311 and electrically connected to the film capacitor 20. a first positive input section 312 of the positive electrode 201, the first negative current bus bar 32 has an electrical connection to each of the power modes a first negative connection section 321 between the first negative electrodes 222, and a first negative input section 322 connected to the first negative connection section 321 and electrically connected to the first input negative electrode 202 of the film capacitor 20, the second The positive bus bar 33 has a second positive connecting portion 331 electrically connected to the second positive electrode 223 of each power module 2, and a second connecting the second positive connecting portion 331 and electrically connecting the thin film capacitor 20 The second positive input section 332 of the positive electrode 203 is connected to the second negative electrode connecting section 341 electrically connected to the second negative electrode 224 of each power module 2, and a connection The second negative electrode connecting portion 341 is electrically connected to the second negative input portion 342 of the second input negative electrode 204 of the film capacitor 20 , and the third positive electrode bus bar 35 has a third positive electrode 225 electrically connected to each of the power modules 2 . a third positive connection section 351, and a third positive input section 352 connected to the third positive connection section 351 and electrically connected to the third input positive electrode 205 of the film capacitor 20, the third negative bus bar 36 has an electrical connection Between the third negative electrodes 226 of each of the power modules 2 The third section 361 connected to the negative electrode, negative electrode and the third connector 361 and a connector section electrically connected to the thin film capacitor 20 of the third input of the third negative electrode 206 negative electrode 362 of the input section.

It should be noted that the first to third positive bus bars 31, 33, 35 and the first to third negative bus bars 32, 34, 36 are actually copper rows, which are spaced apart from each other, and because one of the electric powers The first positive electrode 221, the second positive electrode 223, and the third positive electrode 225 of the input electrode unit 22 of the module 2 are respectively associated with the first negative electrode 222, the second negative electrode 224, and the second power module 2 The positions of the three negative electrodes 226 are correspondingly upper and lower, and the first to third positive electrode bus bars 31, 33, 35 and the first to third negative electrode bus bars 32, 34, 36 are all in a "ㄣ" shape to connect two power modules in parallel. Input electrode unit 22 of 2. The distance between the first positive input section 312 of the first positive bus bar 31 and the first positive connecting section 311 is substantially along the distance from the first positive connecting section 311 to the two first positive poles 221 of the two power modules 2 Similarly, the remaining bus bars 32, 33, 34, 35, 36 are also the same design and so on, and will not be described again. Such a design can effectively reduce the current difference value input to the two power modules 2 because the resistance of the bus bar is proportional to its length.

Referring to FIG. 3 and FIG. 5 , the current output conducting unit 4 is electrically connected between the output electrode unit 23 and the motor (not shown), and includes a first output electrode electrically connected to each of the power modules 2 . a first bus bar 41 between 231, a second bus bar 42 electrically connected between the second output electrodes 232 of each power module 2, and a second electrically connected to each of the power modules 2 A third bus bar 43 between the three output electrodes 233. The first bus bar 41 has a first connecting segment 411 electrically connected between the first output electrodes 231 of each power module 2, and a first connecting the first connecting segment 411 and electrically connecting the motor. An output section 412, the first output section 412 is connected to the middle of the first connection section 411, and the second bus bar 42 has a second electrically connected between the second output electrodes 232 of each power module 2 a connecting portion 421, and a second output portion 422 connected to the middle of the second connecting portion 421 and electrically connected to the motor, the third bus bar 43 has a third output electrode electrically connected to each of the power modules 2 A third connecting section 431 between 233, and a third output section 432 connected to the third connecting section 431 and electrically connected to the motor, the third output section 432 is connected to the middle of the third connecting section 431. The first connecting portion 411 has two first horizontal plate portions 411a electrically connected to the first output electrodes 231 of the power modules 2, and a first connecting between the two first horizontal plate portions 411a. a first plate segment 411b, the first output segment 412 is connected to the first vertical plate portion 411b, the first output segment 412 is respectively spaced apart from the two first transverse plate portions 411a by a distance, and the second connecting segment 421 has Two second horizontal plate portions 421a electrically connecting the second output electrodes 232 of the power modules 2, and a second vertical plate portion 421b connected between the two second horizontal plate portions 421a. The second output section 422 is connected to the second vertical plate portion 421b, and the second output segment 422 is respectively spaced apart from the two second horizontal plate portions 421a by a distance. The third connection segment 431 has two electrical connections respectively. a third horizontal plate portion 431a of the third output electrode 233 of the power module 2, and a third vertical plate portion 431b connected between the two third horizontal plate portions 431a, the third output portion 432 is connected to the third output plate 431a The third vertical plate portion 431b has the same distance from the third horizontal plate portion 431a.

It should be noted that the first to third bus bars 41, 42, 43 are actually copper bars, and the first output segments 412 of the first bus bar 41 are respectively spaced apart from the two first horizontal plate portions 411a by the same distance. The rest of the bus bars 42, 43 are also the same design and so on, and will not be described again. Such a design can effectively reduce the three-phase current difference value of the two power modules 2 output, because the resistance of the bus bar is proportional to its length. The first output segment 412 and the third output segment 432 of the embodiment are respectively inverted "L"-shaped, and the second output segment 422 is slightly different from the "I" shape. Without limitation, the first to third output segments 412, 422, and 432 may all be in the same state.

Referring to FIG. 1 , FIG. 3 and FIG. 5 , the following describes the operation flow of the stacked inverter 10 of the present invention. First, the film capacitor 20 firstly passes through the first to third input positive electrodes 201 , 203 , 205 and the first to third input negative electrodes. 202, 204, 206 transmit DC power to the first to third positive electrodes 221, 223, 225 and the first to third negative electrodes 222, 224, 226 of the power module 2 through the current input conducting unit 3, and transmit the power through the power The module 2 converts the direct current into three-phase alternating current, and then outputs the three-phase alternating current to the motor through the current output conducting unit 4. During this process, the temperature of the two power modules 2 will gradually increase. At this time, the cooling water can be added from the water inlet 11 of the connecting base 1 to simultaneously cool the two power modules 2 because the two power modules The heat dissipating members 24 of the two are located in the heat dissipating space S of the connecting base 1, and thus the cooling degree of the two power modules 2 will tend to be consistent, thereby effectively reducing the temperature difference between the two power modules 2, so that the current output The stability is improved.

In summary, the stacked inverters 10 of the present invention are stacked on top of each other through the power modules 2, and the power modules 2 and the current output conducting units 4 are connected in parallel by the power modules 2, that is, The DC power input from the DC power source can be converted into an AC power output for use by the motor, which not only effectively improves the output power of the inverter, but also has a complicated structure and takes up a larger volume than the conventional parallel power module 2. The invention has higher space utilization and makes the components in the vehicle more flexible in configuration. Furthermore, the power modules 2 are respectively installed on the upper and lower sides of the connecting base 1 so that the cooling water can simultaneously cool the power modules 2, thereby effectively reducing the temperature difference between the two power modules 2. Improve the stability of the three-phase current output. And the symmetrical design of the current output conduction unit 4: the first output section 412 of the first bus bar 41 is spaced apart from the two first horizontal plate portions 411a by the same distance, and can effectively reduce the output of the two power modules 2 The phase current difference value is indeed the object of the present invention. Among them, the technical means of this case can also be used in other fields, not limited to vehicles.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the equivalent equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still The scope of the invention is covered.

10‧‧‧Stacked inverter
20‧‧‧ Film Capacitance
201‧‧‧First input positive
202‧‧‧First input negative
203‧‧‧Second input positive
204‧‧‧Second input negative
205‧‧‧ third input positive
206‧‧‧ third input negative
1‧‧‧Connector
11‧‧‧ Inlet
12‧‧‧Water outlet
13‧‧‧ openings
2‧‧‧Power Module
21‧‧‧ body
211‧‧‧ first side
212‧‧‧ second side
22‧‧‧Input electrode unit
221‧‧‧First positive electrode
222‧‧‧ first negative
223‧‧‧second positive
224‧‧‧second negative
225‧‧‧ Third positive electrode
226‧‧‧ third negative
23‧‧‧Output electrode unit
231‧‧‧First output electrode
232‧‧‧second output electrode
233‧‧‧ third output electrode
24‧‧‧ Heat sink
3‧‧‧Current input conduction unit
31‧‧‧First positive bus bar
311‧‧‧First positive connection
312‧‧‧First positive input section
32‧‧‧First negative bus bar
321‧‧‧First negative connection section
322‧‧‧First negative input section
33‧‧‧Second positive bus bar
331‧‧‧second positive connection
332‧‧‧Second positive input section
34‧‧‧Second negative bus bar
341‧‧‧Second negative connection section
342‧‧‧Second negative input section
35‧‧‧ Third positive bus bar
351‧‧‧third positive connection
352‧‧‧ Third positive input section
36‧‧‧ Third negative bus bar
361‧‧‧ Third negative connection section
362‧‧‧ Third negative input section
4‧‧‧Current output conduction unit
41‧‧‧First bus bar
411‧‧‧First connection segment
411a‧‧‧First horizontal plate
411b‧‧‧First Board Department
412‧‧‧First output segment
42‧‧‧Second bus bar
421‧‧‧Second connection
421a‧‧‧Second horizontal plate
421b‧‧‧Second Board
422‧‧‧second output section
43‧‧‧ Third Bus Bar
431‧‧‧ third connection
431a‧‧‧ Third horizontal board
431b‧‧‧The third vertical board department
432‧‧‧ third output segment
S‧‧‧heating space

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a perspective view of an embodiment of a stacked inverter of the present invention electrically connected to a film capacitor; Figure 3 is a perspective exploded view of the embodiment; Figure 4 is a side view of the embodiment; Figure 5 is a perspective view of the embodiment; and Figure 6 is another perspective of Figure 5 Perspective.

Claims (8)

A stacked inverter for converting direct current output from a direct current power source into alternating current for output to a motor, the stacked inverter comprising: two power modules stacked one on top of the other, each power module including An input electrode unit and an output electrode unit are spaced apart from the input electrode unit; a current input conducting unit electrically connected between the DC power source and the input electrode units of the power modules; and a current output A conducting unit electrically connected between the output electrode units and the motor. The stacked inverter of claim 1, wherein the output electrode unit comprises a first output electrode, a second output electrode and a third output electrode, the first output electrode of the two power modules Corresponding positions correspond to positions of the second output electrodes of the two power modules, and positions of the third output electrodes of the two power modules correspond to each other. The stacked inverter of claim 2, wherein each power module further includes a body having a first surface and a second surface opposite to the first surface, the output electrode unit and The input electrode unit is disposed on the first surface, and the second surfaces are opposite to each other. The stacked inverter of claim 3, further comprising a connector disposed between the second faces of the power modules, each power module further comprising a heat dissipation disposed on the second surface Pieces. The stacked inverter of claim 4, wherein the current output conducting unit comprises a first bus bar electrically connected between the first output electrodes of each power module, and an electrical connection a second bus bar between the second output electrodes of the power module, and a third bus bar electrically connected between the third output electrodes of the power modules. The stacked inverter of claim 5, wherein the first bus bar has a first connection segment electrically connected between the first output electrodes of each power module, and a first connection segment Connecting a segment and electrically connecting the first output segment of the motor, the first output segment being connected to the middle of the first connecting segment, the second bus bar having a second output electrode electrically connected to each of the power modules a second connecting section, and a second output section connected to the middle of the second connecting section and electrically connected to the motor, the third bus bar has a third output electrode electrically connected to each of the power modules a third connecting section, and a third output section connecting the third connecting section and electrically connecting the motor, the third output section being connected to the middle of the third connecting section. The stacked inverter of claim 6, wherein the first connecting segment has two first horizontal plate portions respectively electrically connecting the first output electrodes of the power modules, and one connected to the two a first vertical plate portion between the first horizontal plate portions, the first output portion is connected to the first vertical plate portion, and the first output portion is respectively spaced apart from the two first horizontal plate portions by a distance The second connecting section has two second horizontal plate portions respectively electrically connecting the second output electrodes of the power modules, and a second vertical plate portion connected between the two second horizontal plate portions, the second The output section is connected to the second vertical plate portion, and the second output segment is respectively spaced apart from the two second horizontal plate portions by a distance, and the third connection segment has two first electrically connected to the power modules. a third horizontal plate portion of the three output electrodes, and a third vertical plate portion connected between the two third horizontal plate portions, wherein the third output portion is connected to the third vertical plate portion, and the third output portion is respectively The distances from the two third horizontal plate portions are the same. The stacked inverter of claim 3, wherein the input electrode unit comprises a first positive electrode, a first negative electrode, a second positive electrode, a second negative electrode, a third positive electrode, and a third negative electrode. The first positive electrode, the second positive electrode, and the third positive electrode are spaced apart from each other, and the first negative electrode, the second negative electrode, and the third negative electrode are spaced apart from each other, and the first positive electrode and the first negative electrode are adjacent to each other. The second positive electrode and the second negative electrode are adjacent to each other, and the third positive electrode and the third negative electrode are adjacent to each other, wherein the first positive electrode, the second positive electrode, and the third positive electrode of the input electrode unit of one power module Corresponding to the first negative electrode, the second negative electrode and the third negative electrode position of another power module, the current input conducting unit includes a first electrical connection between the first positive electrode of each power module a positive bus bar, a first negative bus bar electrically connected between the first negative electrodes of each power module, and a second positive bus bar electrically connected between the second positive electrodes of each power module One electrically connected to each of the power modules a second negative bus bar between the two negative electrodes, a third positive bus bar electrically connected between the third positive electrodes of the power modules, and a third negative electrode electrically connected to each of the power modules a third negative bus bar having a first positive connecting portion electrically connected between the first positive electrodes of each power module, and a first positive connecting portion connected to the first positive connecting portion and electrically connected to the first positive electrode connecting portion a first positive input section of the DC power supply, the first negative current bus bar has a first negative connection section electrically connected between the first negative electrodes of the power modules, and a first negative connection section is connected to the power supply Connecting a first negative input segment of the DC power supply, the second positive bus bar has a second positive connection segment electrically connected between the second positive electrodes of each power module, and a second positive connection segment is connected And electrically connecting to the second positive input section of the DC power source, the second negative bus bar has a second negative connection section electrically connected between the second negative electrodes of each power module, and a second negative connection is connected Connect the segment and electrically connect the DC power supply a second anode input section, the third anode bus bar has a third positive connection section electrically connected between the third anodes of the power modules, and a third positive connection section is connected and electrically connected to the DC a third positive input section of the power supply, the third negative bus bar has a third negative connection section electrically connected between the third negative electrodes of the power modules, and a third negative connection section is connected and electrically connected The third negative input section of the DC power source.