SWITCHED POWER CONVERTER

• US 20130308362A1
• Filed: 03/25/2013
• Published: 11/21/2013
• Est. Priority Date: 04/04/2012
• Status: Active Grant

• Current Assignee: Inmotion Technologies AB
• Original Assignee: Kollmorgen AB
• Inventors: Karlsson, Ulf Bengt Ingemar, Ohlin, Christer
• Granted Patent: US 9,148,067 B2
• Time in Patent Office: Days
• US Class Current: 363/141
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H05K 7/209 Heat transfer by conduction from internal heat source to heat radiating structure H05K7/20909 takes precedence

Abstract

The present invention relates to a switched power converter comprising a base plate on which at least one heat sink is arranged. The converter further comprises at least one power transistor arranged on a side of the at least one heat sink. Further, at least one spring element is arranged to press against the power transistor arranged on a side of the at least one heat sink and an oppositely facing side of either an adjacent heat sink or a base plate end face parallel to the at least one heat sink.

This is highly advantageous in that a force is applied to the power transistor by the spring element. This will press the power transistor against the heat sink on whose side the transistor is arranged. Thermal contact is thus established between the power transistor and the heat sink, and heat dissipation from the transistor via the heat sink is greatly facilitated. Further, the spring elements are a cost-effective way of attaining a high compressive force on the power transistors.

Claims

1. Switched power converter comprising a base plate on which at least one heat sink is arranged, the converter device further comprising at least one power transistor arranged on a side of the at least one heat sink, which converter comprises

at least one spring element arranged to press against the power transistor arranged on a side of the at least one heat sink and an oppositely facing side of an adjacent heat sink.

2. The switched power converter of claim 1, said at least one spring element being arranged to press against the power transistor arranged on a side of the at least one heat sink and a further power transistor arranged on an oppositely facing side of the adjacent heat sink.

4. The switched power converter of claims 1, said base plate having a plurality of elongated heat sinks arranged parallel to each other and which base plate further has two end faces at a respective end of the base plate extending parallel to the elongated heat sinks, the power converter further comprising power transistors arranged on both sides of each heat sink, which power converter comprises

a plurality of spring elements, each being arranged to press against a first power transistor arranged on one side of the respective heat sink and a second power transistor arranged on the oppositely facing side of the adjacent heat sink when being arranged between two heat sinks, and being arranged to press against a base plate end face and a third power transistor arranged on the oppositely facing side of the adjacent heat sink when arranged between a base plate end face and a heat sink, said spring elements thereby applying a force to the power transistors for pressing the transistors against the heat sinks

5. The switched power converter of claim 1, the at least one spring element being U-shaped when compressed, wherein the two ends of the spring element apply a force in a respective opposite direction.

6. The switched power converter of claim 1, the at least one spring element being V-shaped when compressed, wherein the two ends of the spring element apply a force in a respective opposite direction.

7. The switched power converter of claim 1, further comprising a printed circuit board on which the power transistors are mounted, which printed circuit board is arranged on top of the heat sinks with the transistors facing the base plate, the power converter further comprising a plurality of housings, each arranged to house a respective spring element, said housings being arranged to fit between the first and the second power transistors in case the housing is to be inserted between two heat sinks and being arranged to fit between the third power transistor and a base plate end face in case the housing is to be inserted between a heat sink and an end face.

8. The switched power converter of claim 7, wherein each housing is arranged with one or more openings facing the board, the board further being arranged with at least one corresponding through-hole which at least partly overlaps said on or more openings in the housing, wherein the spring element is arranged to be accessed via the board through-hole to be snapped into a compressed state.

9. The switched power converter of claim 7, wherein each housing is arranged with a first recess in its interior for holding one end of the spring element, and a second recess arranged on an opposite side to the first recess, said second recess being arranged to receive the other end of the spring element when the spring element is snapped into the compressed state.

10. The switched power converter of claim 7, wherein each housing is arranged to be separated in two portions along a vertical section.

11. The switched power converter of claims 1, wherein a flexible insulating sheet material is arranged between each heat sink and the transistors arranged along the sides of the heat sink.

12. The switched power converter of claim 11, wherein current rails are arranged on the heat sinks between the insulating sheet material and the printed circuit board.

13. The switched power converter of claim 12, wherein each current rail carries a respective phase current arranged to be supplied to a converter three-phase load.

14. The switched power converter of claim 12, further comprising

a second printed circuit board on which power converter DC bus capacitors are arranged;

a DC+ bus bar and a DC−

bus bar arranged at each heat sink between said second printed circuit board and the printed circuit board on which the power transistors are arranged; and

fastening means extending vertically from the second printed circuit board to the heat sink via the DC bus bars, the printed circuit board on which the power transistors are arranged and the respective current rail for applying a pressing force acting vertically on the second printed circuit board, the DC+ bus bar, the DC−

bus bar, the printed circuit board on which the power transistors are arranged, and the respective current rail, against the heat sink.

15. The switched power converter of claim 14, wherein

said fastening means is a screw arranged to engage in a threaded aperture in the heat sink at its one end and to engage in a spring at its other end.

16. The switched power converter of claim 1, wherein each heat sink is arranged with a channel in its interior for housing a cooling medium.

17. The switched power converter of claim 1, wherein each heat sink is arranged to be solid and integrated in the base plate, said base plate further being arranged with one or more cooling fins on its underside.

18. The switched power converter of claim 4, wherein the end faces are integrated in the base plate.

19. The switched power converter of claim 1, wherein the power transistors are arranged along the length of each heat sink, and each switch of the power converter comprises a plurality of parallel-connected power transistors.

3. A switched power converter comprising a base plate on which at least one heat sink is arranged, the converter device further comprising at least one power transistor arranged on a side of the at least one heat sink, which converter comprises

at least one spring element arranged to press against the power transistor arranged on a side of the at least one heat sink and an oppositely facing side of a base plate end face parallel to the at least one heat sink.