Power Converter Cooling Body and Bus Bar Integration

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Solution Overview

Problem

The cooling of smoothing capacitors in electric power converters for vehicles is inefficient due to the lack of effective cooling measures for the electrode bus bars, which generates significant Joule heat and contributes to thermal management issues in compact, high-capacity inverters.

Innovation Solution

An electric power converter design that incorporates a cooling body for both the power semiconductor module and the capacitor module, featuring a case with coolant flow channels along its sides and bottom, efficiently cooling the capacitor element and the power semiconductor module, and a bus bar assembly that reduces inductance and improves thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the inverter is increased in current capacity and decreased in size, then the power density is improved, but the cooling of the smoothing capacitor becomes insufficient

Engineering Contradiction:
Improvecurrent capacityVSAvoidcooling efficiency
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The bus bar is integrated with the cooling body to form a unified structure. The cooling body is formed to face both side surfaces of the case and the bottom surface, creating a combined cooling system that simultaneously cools the capacitor module and the bus bar through the coolant flow channels.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cooling body acts as an intermediary between the bus bar and the coolant. It includes coolant flow channels that allow cooling water to flow through, transferring heat from the bus bar to the coolant efficiently.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the bus bar is not provided with cooling measures, then the structure is simple, but the Joule heat generated by the bus bar cannot be sufficiently cooled

Engineering Contradiction:
ImprovestructureVSAvoidJoule heat
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The bus bar is merged with the cooling body to form an integrated structure. This combination allows the cooling function to be incorporated without adding separate cooling components, maintaining structural simplicity while enabling effective cooling of the bus bar.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cooling body includes coolant flow channels through which cooling water flows. This hydraulic cooling system efficiently removes Joule heat from the bus bar by circulating coolant through the integrated cooling channels.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Reliability

If the DC conductor is positioned away from the case wall, then the electrical insulation is improved, but the cooling efficiency of the conductor is reduced

Engineering Contradiction:
Improveelectrical insulationVSAvoidcooling efficiency
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The DC conductor is positioned to face the inner wall surface of the case at specific locations where cooling is most needed. The cooling body is formed to face both side surfaces and the bottom surface, creating localized high-efficiency cooling zones where the conductor is closest to the cooling channels.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design enhances the cooling efficiency of the smoothing capacitor, allowing for a compact implementation of the electric power converter, effectively managing heat and improving the reliability and efficiency of the system.

Implementation Method 1

a cooling body configured to cool the power semiconductor module and the capacitor module

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

an electrode bus bar that may generate large Joule heat

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2717461B1Power conversion apparatus
Publication Date: 2019.02.27 HITACHI AUTOMOTIVE SYST LTD
  • EP2717461B1 patent drawingFigure 1
  • EP2717461B1 patent drawingFigure 2
  • EP2717461B1 patent drawingFigure 3

AI summary

An electric power converter is provided with: a power semiconductor module, which has a power semiconductor element that converts a direct current into an alternating current; a capacitor module, which has a capacitor element that smooths the direct current; and a cooling body, which cools the power semiconductor module and the capacitor module. The capacitor module has: a case, which has an approximately rectangular shape, has an opening formed in one surface, and has a space for housing the capacitor element; and a DC conductor for electrically connecting the power semiconductor element and the capacitor element to each other. The cooling body is formed to face the bottom surface on the inner wall of the case, and both the side surfaces of the case, the side surfaces facing each other. Between the capacitor element and the inner wall surfaces of the case, the direct current conductor is formed along the bottom surface and both the side surfaces of the case.