Power Conversion Cells With Bypass Control For Reliability
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Solution Overview
Problem
Conventional power conversion devices require backup inverters for handling malfunctions in single-phase inverters, which increases complexity and cost.
Innovation Solution
A power conversion device comprising multiple cells with transformers, primary and secondary conversion units, and bypass devices, where a controller manages the bypassing of faulty units to maintain operation without a backup cell, by controlling DC link voltages to prescribed values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backup inverters are provided for handling malfunctions in single-phase inverters, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The power conversion device is divided into multiple independent power conversion cells, each capable of operating autonomously. When a malfunction occurs in one cell, the bypass switch isolates only that specific cell while allowing other cells to continue operation, thereby maintaining system reliability without requiring backup inverters for the entire system.
Solution Approach 2:
Bypass switches are pre-configured in each power conversion cell before operation. These bypass switches are kept ready in advance so that when a malfunction occurs, the controller can immediately activate the bypass path without delay, ensuring continuous operation of healthy cells and maintaining system reliability.
2Reliability
If backup inverters are provided for handling malfunctions, then reliability is improved, but cost increases
Solution Approach 1:
The system segments the power conversion function into multiple cells with individual bypass capabilities. This eliminates the need for expensive backup inverters by allowing graceful degradation where the system continues operating with reduced capacity rather than requiring full backup redundancy.
Solution Approach 2:
Each power conversion cell is self-sufficient with its own bypass switch and control logic. When a cell malfunctions, it automatically isolates itself through the bypass mechanism, allowing the remaining healthy cells to continue serving the system without requiring external backup components.
3Power
If power conversion cells are connected in series for high-voltage output, then power conversion capability is improved, but reliability deteriorates when a cell malfunctions
Solution Approach 1:
The high-voltage power conversion system is segmented into multiple series-connected cells, each equipped with its own bypass switch. This allows the system to maintain high-voltage capability through series connection while providing individual isolation paths for each cell, so that a malfunction in one cell does not compromise the entire system.
Solution Approach 2:
The system dynamically reconfigures the circuit topology by activating bypass switches when malfunctions occur. This allows the system to transition from a rigid series-connection structure to a flexible configuration where faulty cells are electrically isolated, maintaining reliability while preserving the high-voltage power conversion capability of healthy cells.
Data Source
AI summary
A power conversion device includes: power conversion cells; and a controller to control the cells. Each cell includes: a transformer; a primary conversion unit on a primary side of the transformer; a secondary conversion unit on a secondary side; a primary bypass device for short-circuiting between input terminals of the cell; and a secondary bypass device for short-circuiting between output terminals of the cell. The input terminals and/or the output terminals of the cells are connected in series. When the primary conversion unit(s) of a part of the cells is stopped, the controller turns on the primary bypass device and sets secondary DC link voltages to prescribed values; and when the secondary conversion unit(s) of a part of the cells is stopped, the controller turns on the secondary bypass device and controls the primary conversions units to set primary DC link voltages to prescribed values.