Power Conversion Apparatus Dummy Module Surge Suppression
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Solution Overview
Problem
Conventional power conversion apparatuses face issues with large surge voltages applied to semiconductor elements during switching operations due to parasitic inductance in DC bus bars, which can lead to damage or require high breakdown voltage semiconductor elements or reduced switching speed.
Innovation Solution
A power conversion apparatus with a stack structure that alternately includes semiconductor modules, cooling pipes, and dummy modules without semiconductor elements, where the dummy modules are interposed between semiconductor modules with different AC phases, extending the distance of the surge voltage propagation path and reducing the superimposed surge voltage through increased inductance on the DC bus bar.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If semiconductor modules are stacked closely together to increase power conversion capacity, then productivity and power output are improved, but surge voltage increases due to reduced inductance in the current path
Solution Approach 1:
A dummy module is introduced as an intermediary component between semiconductor modules with different AC phases. This dummy module extends the current path length through the DC bus bar, increasing parasitic inductance to suppress surge voltage. The dummy module acts as a mediator that resolves the conflict between compact stacking (for high power) and surge voltage suppression (requiring longer current paths).
Solution Approach 2:
The invention changes the physical parameter of the current path length by inserting a dummy module. This increases the parasitic inductance value in the circuit, which directly affects the surge voltage characteristics. By modifying this physical parameter, the system achieves surge voltage suppression without reducing the overall power conversion capacity.
2Reliability
If semiconductor elements with high breakdown voltage are used to withstand surge voltage, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The invention converts the harmful surge voltage generated by parasitic inductance into a beneficial design feature. Instead of trying to eliminate the parasitic inductance or its effects, the design intentionally utilizes and enhances it by adding the dummy module. This transforms the harmful surge voltage phenomenon into a protective mechanism that suppresses voltage spikes, allowing the use of standard semiconductor elements rather than high-breakdown-voltage components.
3Object-affected harmful factors
If switching speed is reduced to lower surge voltage, then surge voltage is suppressed, but productivity and power conversion efficiency deteriorate
Solution Approach 1:
The invention segments the stack structure by introducing a dummy module that contains no semiconductor elements. This segmentation creates a dedicated zone for surge voltage suppression between functional semiconductor modules. The segmentation allows different parts of the system to have different functions: semiconductor modules for power conversion and dummy modules for electrical isolation and inductance enhancement, enabling high switching speeds without excessive surge voltage.
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
The solution effectively suppresses large superimposed surge voltages applied to semiconductor elements, allowing for higher current flow while maintaining suppressed surge voltage, thus preventing damage and enabling faster switching speeds without the need for high breakdown voltage semiconductor elements.
Implementation Method 1
a plurality of cooling pipes that cool the semiconductor modules
Implementation Method 2
a pair of DC bus bars that constitute a current path between a DC power source and respective semiconductor modules
Data Source
AI summary
A power conversion apparatus includes a plurality of semiconductor modules each having a semiconductor element integrated thereto; a plurality of cooling pipes that cools the semiconductor modules; a plurality of dummy modules with no integrated semiconductor element; and a pair of DC bus bars that constitute a current path between a DC power source and respective semiconductor modules. The semiconductor modules or the dummy modules, and the cooling pipes are alternately stacked to form a stack; m the plurality of semiconductor modules constitute an inverter circuit that converts a DC power supplied from the DC power source into a multi-phase AC power in which a plurality of types of AC outputs having mutually different phases are combined; and the dummy modules are each interposed between two semiconductor modules having mutually different phases of the AC outputs.