Converter Inverter Cooling Layout for Electric Railcars

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Solution Overview

Problem

Existing power systems for storage battery electric railcars do not effectively cool semiconductor elements within the main conversion circuit, particularly converters and inverters, which can lead to temperature biases and inefficient cooling.

Innovation Solution

An electric motor power system that includes a converter-inverter and a cooler, where the cooler effectively cools both the converter and inverter, with the converter-inverter configured to convert AC power to DC power and the inverter converting DC power to three-phase AC power, and the cooler is utilized to cool the converter even when the inverter is stopped, allowing for efficient charging of the storage battery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the cooler is dedicated only to the inverter, then the inverter cooling is ensured, but the converter cannot be cooled effectively when the inverter is stopped

Engineering Contradiction:
Improveconverter temperatureVSAvoidcooler utilization flexibility
Core Design Contradiction:
TemperatureVSAdaptability or versatility

Solution Approach 1:

The cooler is designed to serve both the converter and the inverter through a shared cooling system. The cooling system can dynamically allocate cooling capacity to either device based on operational needs, allowing the single cooler to perform multiple cooling functions and improving overall system efficiency

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Temperature

If the converter and inverter are cooled separately, then each device can be optimized independently, but the cooling system complexity increases

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcooling system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cooling systems for the converter and inverter are merged into a single integrated cooler unit. This unified cooling system uses common cooling media and shared thermal management components, reducing the overall number of cooling devices while maintaining effective cooling capability for both power conversion devices

Inventive Principle:
Principle #5Merging (Combining)

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 configuration reduces temperature biases and enhances cooling efficiency, allowing for effective cooling of the converter and inverter, and enables rapid charging of the storage battery during vehicle stops by utilizing the cooler's energy when the inverter is inactive.

Implementation Method 1

a cooler cools, for example, semiconductor elements that belong to a main conversion circuit

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

EP A1 2787624 proposes a forced-air-cooled power conversion device

Methodology Applied
Scientific EffectForced convection: Forced Convection

Data Source

PatentEP3530514B1Electric motor power system, and electric vehicle
Publication Date: 2022.03.02 HITACHI LTD
  • EP3530514B1 patent drawingFigure 1
  • EP3530514B1 patent drawingFigure 2~3
  • EP3530514B1 patent drawingFigure 4

AI summary

The present invention relates to a power system provided with coolers for cooling converters and inverters, wherein element groups belongs to the converters are disposed divided into a plurality of blocks with element groups belonging to the inverters provided therebetween. More preferably, in the present invention, storage batteries are connected to DC circuits which link the converters and the inverters. According to the present invention, bias in the temperatures of the converters and inventers can be reduced, and cooling can be effectively performed by the coolers. When the inverters are stopped, the coolers can be fully utilized to cool the converters while the storage batteries are being charged.