Electric Power Converter

• US 20080049476A1
• Filed: 07/19/2007
• Published: 02/28/2008
• Est. Priority Date: 07/21/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Mori, Mutsuhiro, Nakatsu, Kinya, AZUMA, Katsunori
• Granted Patent: US 7,742,303 B2
• Time in Patent Office: Days
• US Class Current: 363/131
• CPC Class Codes: B60L 15/007 Physical arrangements or structures of drive train converters specially adapted for the propulsion motors of electric vehicles
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/525 Temperature of converter or components thereof
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 3/12 Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/60 using power supplied by batteries in combination with fuel cells B60L50/75
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48139 with an intermediate bond, e.g. continuous wire daisy chain
• CPC Class Codes: H01L 2224/4846 with multiple bonds on the same bonding area
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/49111 the connectors connecting two common bonding areas, e.g. Litz or braid wires
• CPC Class Codes: H01L 2224/49113 the connectors connecting different bonding areas on the semiconductor or solid-state body to a common bonding area outside the body, e.g. converging wires
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/1305 : Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/13055 : Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2924/1306 : Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/19107 : off-chip wires
• CPC Class Codes: H01L 2924/30107 : Inductance
• CPC Class Codes: H02M 7/003 : Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H05K 7/20927 : Liquid coolant without phase change
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

The present invention provides a highly reliable electric power converter reduced in parasitic inductance.

An electric power converter that includes a capacitor module which has a DC terminal, an inverter which coverts a direct current into an alternating current, and heat release fins which cool the inverter, is constructed so that: the inverter has a power module including a plurality of power semiconductor elements; the power module further has a metallic base, a dielectric substrate provided on one face of the metallic base, a power semiconductor element fixed to the dielectric substrate, and a DC terminal; the metallic base has the heat release fins on the other face; the DC terminal in the power module and the DC terminal in the capacitor module are each formed by stacking flat plate conductors via an insulator; the two positive and negative DC terminals have respective front ends bent in opposite directions; a plane including the bent sections is used as a surface for connecting the power module and the capacitor module; and the insulators overlap each other at the connection surface.

Claims

1. An electric power converter comprising:

a capacitor module having a first pair of positive and negative DC terminals formed by stacking flat plate conductors via a first insulator; and

a power module having a second pair of positive and negative DC terminals formed by stacking other flat plate conductors via a second insulator, said power module further including a plurality of power semiconductor elements each for converting DC power supplied from said second pair of said DC terminals into three-phase AC power;

wherein;

said first pair of said positive and negative DC terminals is constructed such that said associated flat plate conductors are bent in directions opposite to each other at a front end of said terminal pair, and has a first connection surface electrically connected to said second pair of said positive and negative DC terminals, at an end of any one of said bent conductors;

said second pair of said positive and negative DC terminals is constructed such that said associated flat plate conductors are bent in directions opposite to each other at a front end of said terminal pair, and has a second connection surface electrically connected to said first pair of said positive and negative DC terminals, at an end of any one of said bent conductors; and

in a connection region between said first connection surface and said second connection surface, said first insulator and said second insulator overlap each other.

2. An electric power converter comprising:

a cooling water channel formed for a cooling medium to flow therethrough;

a metallic base mounted on said cooling water channel; and

a power module mounted on said metallic base;

wherein;

said power module includes

a dielectric substrate,

a plurality of power semiconductor elements each mounted on said dielectric substrate in order to convert DC power into three-phase AC power, and

a plurality of DC terminal pairs each for supplying said DC power;

said plurality of DC terminal pairs each have a capacitor electrically connected thereto;

each of said plural DC terminal pairs further has flat plate conductors stacked via a sheet insulator; and

at a front end of each of said plural DC terminal pairs, said flat plate conductors are bent in directions opposite to each other, and at an end of any one of said bent conductors, said DC terminal pair has a surface for electrical connection to said capacitor.

3. The electric power converter according to claim 2, wherein:

said plurality of DC terminal pairs each include said flat plate conductors arranged such that sagging surfaces thereof face each other.

4. An electric power converter comprising:

a housing;

a capacitor module with a DC terminal in said housing;

an inverter with another DC terminal to which DC power is supplied, and with an AC terminal for supplying three-phase AC power to a rotating electric machine; and

heat release fins for cooling said inverter;

wherein;

said inverter includes a power module that has a plurality of switching power semiconductor chips and a driver circuit board on which a driver circuit is provided for controlling said switching power semiconductor chips;

said power module includes a metallic base, a dielectric substrate on one face of said metallic base, said switching power semiconductor chips each fixed to said dielectric substrate, and said DC terminal of said inverter;

said metallic base has said heat release fins on another face of said base; and

said DC terminal of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

5. The electric power converter according to claim 4, wherein:

said DC terminal of said power module includes a positive DC terminal and a negative DC terminal, said positive and negative DC terminals each including a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion, and said intermediate conductors of said positive and negative DC terminals forming a stacked structure which has an insulator sandwiched between said terminals; and

said conductor-side connecting portions of said positive and negative DC terminals are electrically connected to a first wide conductor and a second wide conductor, respectively, both of said conductors forming said stacked structure.

6. The electric power converter according to claim 5, wherein:

said conductor-side connecting portions of said positive and negative DC terminals are bent in directions opposite to each other;

power module side end portions of said first wide conductor and second wide conductors forming said stacked structure are bent in directions opposite to each other; and

said bent conductor-side connecting portions of said positive and negative DC terminals are electrically connected to said bent power module side end portions of said first wide conductor and second wide conductors, respectively.

7. The electric power converter according to claim 5, wherein:

said chip-side connecting portions of said positive and negative DC terminals each have a plurality of leads; and

said leads of said positive DC terminal are bent in a direction opposite to a direction in which said leads of said negative DC terminal are bent.

8. The electric power converter according to claim 7, wherein:

said dielectric substrate of said power module has a positive conductor and a negative conductor; and

a lead of said positive DC terminal and a lead of said negative DC terminal are electrically connected to said positive conductor and said negative conductor, respectively, by soldering.

9. The electric power converter according to claim 7, wherein:

said dielectric substrate of said power module has a positive conductor and a negative conductor; and

a lead of said positive DC terminal and a lead of said negative DC terminal are electrically connected to said positive conductor and said negative conductor, respectively, by ultrasonic connection.

10. An electric power converter comprising:

a housing;

a capacitor module with a DC terminal in said housing;

an inverter with an AC terminal for supplying three-phase AC power to a rotating electric machine, and with a positive DC terminal and negative DC terminal to which DC power is supplied; and

heat release fins for cooling said inverter;

wherein;

said inverter includes a power module that has a plurality of switching power semiconductor chips and a driver circuit board on which is provided a driver circuit for controlling said switching power semiconductor chips;

said power module includes a metallic base, said switching power semiconductor chips each fixed to one face of said metallic base via a dielectric substrate, a positive conductor and negative conductor fixed to another face of said metallic base via said dielectric substrate, and said positive and negative DC terminals of said inverter;

said positive and negative DC terminals each include a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion, and said intermediate conductor of said positive DC terminal and said intermediate conductor of said negative DC terminal form a stacked structure with an insulator sandwiched between said intermediate conductors;

said chip-side connecting portions of said positive and negative DC terminals are electrically connected to said positive and negative conductors, respectively, that are fixed to said metallic base of said power module; and

said positive and negative DC terminals of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

11. The electric power converter according to claim 10, wherein:

said conductor-side connecting portions of said positive and negative DC terminals are bent in directions opposite to each other;

power module side end portions of said first wide conductor and second wide conductors forming said stacked structure are bent in directions opposite to each other; and

said bent conductor-side connecting portions of said positive and negative DC terminals are electrically connected to said bent power module side end portions of said first wide conductor and second wide conductors, respectively.

12. The electric power converter according to claim 10, wherein:

said chip-side connecting portions of said positive and negative DC terminals each have a plurality of leads; and

said leads of said positive DC terminal are bent in a direction opposite to a direction in which said leads of said negative DC terminal are bent.

13. The electric power converter according to claim 12, wherein:

said dielectric substrate of said power module has a positive conductor and a negative conductor; and

a lead of said positive DC terminal and a lead of said negative DC terminal are electrically connected to said positive conductor and said negative conductor, respectively, by soldering.

14. The electric power converter according to claim 12, wherein:

said dielectric substrate of said power module has a positive conductor and a negative conductor; and

a lead of said positive DC terminal and a lead of said negative DC terminal are electrically connected to said positive conductor and said negative conductor, respectively, by ultrasonic connection.

15. An electric power converter comprising:

a metallic housing;

a power module disposed inside said housing;

a capacitor module disposed inside said housing; and

a water channel formation forming a cooling water channel;

wherein;

an opening is formed in said cooling water channel;

said power module has a metallic base and a positive DC terminal and negative DC terminal for supplying DC power to said power module;

said metallic base has heat release fins on one face thereof, said base further having on another face thereof a plurality of semiconductor chips and a positive conductor and negative conductor for supplying said DC power to each of said semiconductor chips;

said heat release fins of said power module protrude from said opening into said cooling water channel, said opening being blocked with said metallic base of said power module;

said positive and negative DC terminals each include a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion;

said intermediate conductor of said positive DC terminal and said intermediate conductor of said negative DC terminal form a stacked structure with an insulator sandwiched between said intermediate conductors;

said chip-side connecting portions of said positive and negative DC terminals are electrically connected to said positive and negative conductors, respectively, that are fixed to said metallic base of said power module; and

said positive DC terminal and negative DC terminal of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

16. An electric power converter comprising:

a metallic housing;

a water channel formation forming a cooling water channel disposed in said housing;

a power module disposed inside said housing; and

a capacitor module disposed inside said housing;

wherein;

an opening is formed in said cooling water channel;

said power module includes a positive DC terminal and negative DC terminal for supplying DC power to said power module, a metallic base plate, heat release fins fixed to one face of said metallic base, and a plurality of semiconductor chips each retained on another face of said metallic base;

said power module is fixed to said water channel formation with said power module protruding said heat release fins thereof from said opening into said cooling water channel;

an inlet pipe for receiving cooling water, an outlet pipe for discharging said cooling water are fixed to said housing, wherein an inlet port of said cooling water channel, formed to introduce said cooling water from said inlet pipe, is deep, compared with a section at which said heat release fins of said cooling water channel protrude, and wherein an outlet port of said cooling water channel, formed to introduce said cooling water into said outlet pipe, is deep, compared with said protruding section of said heat release fins of said cooling water channel; and

said positive DC terminal and negative DC terminal of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

17. An electric power converter comprising:

a metallic housing;

a water channel formation forming a cooling water channel disposed in said housing;

a power module disposed inside said housing; and

a capacitor module disposed inside said housing;

wherein;

an opening is formed in said cooling water channel;

said power module includes a positive DC terminal and negative DC terminal for supplying DC power to said power module, a metallic base plate, heat release fins fixed to one face of said metallic base, and a plurality of semiconductor chips each retained on another face of said metallic base;

said power module is fixed to said water channel formation with said power module protruding said heat release fins thereof from said opening into said cooling water channel;

an inlet pipe for receiving cooling water, an outlet pipe for discharging said cooling water are fixed to said housing, wherein an inlet port of said cooling water channel, formed to introduce said cooling water from said inlet pipe, is deep, compared with a section at which said heat release fins of said cooling water channel protrude, and wherein an outlet port of said cooling water channel, formed to introduce said cooling water into said outlet pipe, is deep, compared with said protruding section of said heat release fins of said cooling water channel;

said positive DC terminal and negative DC terminal of said power module each include a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion;

said intermediate conductor of said positive DC terminal and said intermediate conductor of said negative DC terminal form a stacked structure with an insulator sandwiched between said intermediate conductors;

said chip-side connecting portions of said positive and negative DC terminals are electrically connected to said positive and negative conductors, respectively, that are fixed to said metallic base of said power module; and

said positive and negative DC terminals of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

18. An electric power converter comprising:

a metallic housing;

a water channel formation adapted to form cooling water channels;

a plurality of power modules disposed inside said housing; and

a capacitor module disposed inside said housing;

wherein;

said water channel formation has said cooling water channels disposed in parallel to each other;

an opening is formed in each of said cooling water channels;

said power modules each include a positive DC terminal and negative DC terminal for supplying DC power to said power module, a metallic base, heat release fins fixed to one face of said metallic base, a plurality of semiconductor chips fixed to another face of said metallic base, and a positive conductor and negative conductor fixed to the same face as the face to which said semiconductor chips are fixed, said positive and negative conductors being disposed to supply the DC power to said semiconductor chips;

one of said power modules is retained on said water channel formation with said power module protruding said heat release fins thereof from said opening in one of said parallel-disposed water channels into said associated water channel such that said opening is blocked with said metallic base of said power module;

the other power module is retained on said water channel formation with said power module protruding said heat release fins thereof from said opening in the other parallel-disposed water channel into said associated water channel such that said opening is blocked with said metallic base of said power module;

said positive and negative DC terminals of said power module each include a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion, and said intermediate conductor of said positive DC terminal and said intermediate conductor of said negative DC terminal form a stacked structure with an insulator sandwiched between said intermediate conductors;

said chip-side connecting portions of said positive and negative DC terminals are electrically connected to said positive and negative conductors, respectively, that are fixed to said metallic base of said power module; and

said positive and negative DC terminals of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

19. An electric power converter comprising:

a metallic housing;

a water channel formation adapted to form cooling water channels;

a plurality of power modules disposed inside said housing; and

a capacitor module disposed inside said housing;

wherein;

said water channel formation has said cooling water channels disposed in parallel to each other;

an opening is formed in each of said cooling water channels;

said power modules each include a positive DC terminal and negative DC terminal for supplying DC power to said power module, a metallic base, heat release fins fixed to one face of said metallic base, and a plurality of semiconductor chips fixed to another face of said metallic base;

one of said power modules is retained on said water channel formation with said power module protruding said heat release fins thereof from said opening in one of said parallel-disposed water channels into said associated water channel such that said opening is blocked with said metallic base of said power module;

the other power module is retained on said water channel formation with said power module protruding said heat release fins thereof from said opening in the other parallel-disposed water channel into said associated water channel such that said opening is blocked with said metallic base of said power module;

an inlet pipe for receiving cooling water, an outlet pipe for discharging said cooling water are fixed to said housing, wherein an inlet port of said cooling water channel, formed to connect to said inlet pipe thereof, is deep, compared with a section at which said heat release fins of said cooling water channel protrude, wherein an outlet port of said cooling water channel, formed to connect to said outlet pipe thereof, is deep, compared with said protruding section of said heat release fins of said cooling water channel, and wherein bends in said cooling water channel, formed to connect said cooling water channels arranged in parallel, are deep, compared with said protruding section of said heat release fins of said cooling water channel;

said positive and negative DC terminals of said power module each include a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion, and said intermediate conductor of said positive DC terminal and said intermediate conductor of said negative DC terminal form a stacked structure with an insulator sandwiched between said intermediate conductors;

said chip-side connecting portions of said positive and negative DC terminals are electrically connected to said positive and negative conductors, respectively, that are fixed to said metallic base of said power module; and

said positive and negative DC terminals of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

20. An electric power converter comprising:

a metallic housing;

a power module disposed inside said housing;

a capacitor module disposed inside said housing; and

a water channel formation forming a cooling water channel;

wherein;

an opening is formed in said cooling water channel;

said power module includes a positive DC terminal and negative DC terminal for supplying DC power to said power module, a metallic base, heat release fins provided on one face of said metallic base, a plurality of semiconductor chips retained on another face of said metallic base;

with said heat release fins protruding from said opening into said cooling water channel and with said opening blocked with said metallic base of said power module, said power module is fixed to one face of said water channel formation, whereas said capacitor module is fixed to another face of said water channel formation;

said positive and negative DC terminals of said power module each include a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion;

said intermediate conductor of said positive DC terminal and said intermediate conductor of said negative DC terminal form a stacked structure with an insulator sandwiched between said intermediate conductors;

said chip-side connecting portions of said positive and negative DC terminals are electrically connected to said positive and negative conductors, respectively, that are fixed to said metallic base of said power module; and

said positive and negative DC terminals of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

21. An electric power converter comprising:

a metallic housing;

a water channel formation fixed to said housing in order to form a cooling water channel;

a power module;

a capacitor module; and

heat release fins for cooling said power module;

wherein;

an opening is formed in said cooling water channel, and said heat release fins protrude from said opening into said cooling water channel;

said power module includes a positive DC terminal and negative DC terminal for receiving a supply of DC power, a metallic base, a plurality of semiconductor chips retained on one face of said metallic base, a positive conductor, and a negative conductor, and another face of said metallic base is thermally connected to said heat release fins;

said power module is positioned at one side of said cooling water formation, and said capacitor module is positioned at the other side of said cooling water formation;

an inlet for receiving cooling water, and an outlet for discharging said cooling water are disposed in said housing, wherein an inlet port of said cooling water channel, formed to connect to said inlet, is deep, compared with a section at which said heat release fins of said cooling water channel protrude, and wherein an outlet port of said cooling water channel, formed to connect to said outlet, is deep, compared with said protruding section of said heat release fins of said cooling water channel;

said positive and negative DC terminals of said power module each include a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion;

said intermediate conductor of said positive DC terminal and said intermediate conductor of said negative DC terminal form a stacked structure with an insulator sandwiched between said intermediate conductors;

said chip-side connecting portions of said positive and negative DC terminals are electrically connected to said positive and negative conductors, respectively, that are fixed to said metallic base of said power module; and

said positive and negative DC terminals of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.

22. An electric power converter comprising:

a metallic housing;

a plurality of power modules disposed inside said housing;

a capacitor module disposed inside said housing; and

a water channel formation adapted to form cooling water channels through which to supply cooling water;

wherein;

said water channel formation internally has said cooling water channels disposed in parallel to each other;

said power modules each include a positive DC terminal and negative DC terminal for receiving DC power, a metallic base, a plurality of semiconductor chips retained on one face of said metallic base, a positive conductor, and a negative conductor;

said metallic base of one of said power modules is connected at one face of said base to said cooling water within one of said parallel-arranged water channels via a heat-conducting member;

said metallic base of the other power module is connected at one face of said base to said cooling water within the other parallel-arranged water channel via a heat-conducting member;

said capacitor module is fixed to another face of said water channel formation;

said positive and negative DC terminals of said power module each include a conductor-side connecting portion, a chip-side connecting portion, and an intermediate conductor for connecting said conductor-side connecting portion and said chip-side connecting portion;

said intermediate conductor of said positive DC terminal and said intermediate conductor of said negative DC terminal form a stacked structure with an insulator sandwiched between said intermediate conductors;

said chip-side connecting portions of said positive and negative DC terminals are electrically connected to said positive and negative conductors, respectively, that are fixed to said metallic base of said power module; and

said positive and negative DC terminals of said power module and said DC terminal of said capacitor module are electrically interconnected using a first wide conductor and a second wide conductor, respectively, wherein a sheet insulator is disposed between said first wide conductor and said second wide conductor, and wherein said first wide conductor, said second wide conductor, and said sheet insulator are formed into a stacked structure.