Double-Sided Cooling Layout for Thin Sealed Power Converters

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Solution Overview

Problem

Existing power conversion devices are not adequately thin and efficient in cooling performance while maintaining sealing performance to prevent refrigerant leakage.

Innovation Solution

A power conversion device design incorporating a first and second substrate with flow path forming bodies that form refrigerant paths on both surfaces, cooling power modules from both sides and preventing refrigerant leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a three-phase bridge rectifier circuit is used, then the power conversion device can be compact and lightweight, but the number of switching elements increases leading to higher loss and reduced reliability

Engineering Contradiction:
Improvedevice volumeVSAvoidswitching element loss
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent divides the three-phase bridge rectifier circuit into two separate single-phase bridge rectifier circuits. Each single-phase circuit processes one phase independently, reducing the number of switching elements required in each circuit while maintaining the overall power conversion functionality. This segmentation allows for fewer switching elements per phase, thereby reducing total loss and improving reliability.

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If a three-phase bridge rectifier circuit is used, then the power conversion device can be compact and lightweight, but the complexity of the control circuit increases

Engineering Contradiction:
Improvedevice volumeVSAvoidcontrol circuit complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The control circuit is segmented into two independent control circuits, each managing one single-phase bridge rectifier circuit. This segmentation simplifies the control logic for each individual circuit compared to controlling a three-phase bridge rectifier, as each control circuit only needs to manage two switching elements rather than six. The independent control of single-phase circuits reduces overall control complexity.

Inventive Principle:
Principle #1Segmentation

3Power

If six switching elements are used in a three-phase bridge rectifier, then power conversion is achieved, but the device exhibits poor resistance to transient overvoltage

Engineering Contradiction:
Improvepower conversion capabilityVSAvoidtransient overvoltage resistance
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

By segmenting the three-phase bridge rectifier into two single-phase bridge rectifiers, the patent reduces the number of switching elements from six to four total. This reduction decreases the potential failure points and improves transient overvoltage resistance. Each single-phase circuit with fewer switching elements demonstrates better resistance to transient overvoltage compared to a conventional three-phase bridge rectifier with six switching elements.

Inventive Principle:
Principle #1Segmentation

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

Achieves a thinner power conversion device with enhanced cooling and sealing performance, efficiently cooling power modules and control circuit substrates while preventing refrigerant leakage.

Implementation Method 1

a first diode bridge circuit 11 that performs rectification of the AC power

Methodology Applied
Scientific EffectRectification: Diode

Implementation Method 2

a capacitor 12 for smoothing the rectified power

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 3

a DC-DC converter 20 that transforms the DC power into power having a predetermined voltage

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4131357B1Power conversion device
Publication Date: 2026.05.06 HITACHI LTD
  • EP4131357B1 patent drawingFigure 1
  • EP4131357B1 patent drawingFigure 2
  • EP4131357B1 patent drawingFigure 3

AI summary

A power conversion device according to the present invention comprises: a capacitor which is for smoothing DC power; a plurality of power modules which are for converting the DC power to AC power; a first substrate on which the plurality of power modules are installed; a second substrate which is disposed facing the first substrate; a first flow path forming body which, together with a surface of the first substrate and a surface of the second substrate, forms a flow path for circulating a refrigerant; and a second flow path forming body which forms the flow path together with the surface of the first substrate, wherein both surfaces of each of the power modules are cooled by the refrigerant.