Electric Power Converter with Equipotential Cooler for Surge Management
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Solution Overview
Problem
Conventional electric power conversion devices face challenges in downsizing semiconductor modules due to conflicting performance of insulation and size, leading to issues with surge voltage and noise generation.
Innovation Solution
The electric power conversion device incorporates a semiconductor module with a series connection of switching elements and rectification elements, along with an adjustment portion that includes capacity elements and a cooler, where the potential of the middle point between the capacity elements is equal to the cooler's potential, enhancing insulation performance and allowing for smaller module sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If semiconductor modules are downsized, then the size of the semiconductor module is reduced, but the distance between the cooler and terminals becomes short causing insulation performance to deteriorate
Solution Approach 1:
The patent applies equipotentiality by connecting the cooler to the negative electrode frame, ensuring they share the same potential. This eliminates potential difference between the cooler and low potential side terminals, preventing discharge even when the distance is short due to downsizing. The cooler and negative electrode frame form an equipotential body, resolving the insulation problem while allowing compact module design.
Solution Approach 2:
The negative electrode frame acts as an intermediary between the cooler and the low potential side terminals. By connecting the cooler to the negative electrode frame, the frame mediates the electrical relationship, ensuring that the cooler is at the same potential as the terminals. This intermediary connection prevents discharge paths from forming, allowing short distances without compromising insulation.
2Productivity
If switching elements are turned on/off frequently, then power conversion efficiency is improved, but surge voltage and noise are generated
Solution Approach 1:
The patent converts the harmful surge voltage and noise generated by switching operations into a beneficial effect by providing a controlled discharge path through the cooler. The cooler, being at the same potential as the negative electrode frame, serves as a safe discharge destination for parasitic inductance-induced surges, converting potentially harmful random discharges into controlled, harmless current flow that improves overall system reliability.
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 enhances insulation performance, enabling the semiconductor modules to be made smaller while maintaining effective surge voltage management and creepage surface insulation, thereby addressing the size vs. insulation tradeoff.
Implementation Method 1
The cooler is connected to the semiconductor module via an insulating plate
Implementation Method 2
The adjustment portion includes a first capacity element, a second capacity element and a cooler. The adjustment portion is configured such that a potential of a middle point between the first capacity element and the second capacity element is equal to a potential of the cooler
Data Source
AI summary
In a converter circuit of an electric power conversion device, an adjustment portion divides a voltage of a battery input to a semiconductor module, by a first capacity element and a second capacity element that are connected in series to each other. Then, a middle point between the first capacity element and the second capacity element is connected to a cooler to fix a potential thereof. The electric power conversion device can ensure that a waveform of a surge voltage that is generated on a creepage surface between a lead frame terminal and the cooler has a negative voltage range (a range where an offset voltage is applied).