Current-Responsive Power Converter Redundancy With Standby Switching
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Solution Overview
Problem
The existing power conversion device for electric railway vehicles lacks sufficient redundancy, as it has only one contactor, leading to a failure in power conversion processing when the contactor fails, despite having redundant power converters.
Innovation Solution
A power conversion device with multiple power conversion units, each including a power converter, contactor, and unit controller, connected in common to the power source, with a contactor controller and sensors to measure current values and determine unit failures, enabling switching between operation and standby units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple power conversion units with redundant power converters are provided, then reliability is improved, but device complexity increases due to multiple contactors and control systems
Solution Approach 1:
The power conversion device is divided into multiple independent power conversion units (first and second units), each with its own contactor and control system. This segmentation allows each unit to operate independently, so that failure of one unit does not affect the other, thereby improving reliability while maintaining manageable complexity through modular design
Solution Approach 2:
The system performs preliminary determination of contactor failure states by comparing commanded states with actual states before they affect power conversion operations. The control device detects failure modes in advance and can switch to standby units proactively, preventing complete system failure and maintaining continuous operation
2Device complexity
If a single contactor is used to control power converters, then device complexity is reduced, but reliability deteriorates because contactor failure disables all power conversion processing
Solution Approach 1:
Instead of using a single contactor for all power converters, the system segments the contactor control function across multiple independent contactors (first contactor for first power conversion unit, second contactor for second power conversion unit). This segmentation ensures that contactor failure is isolated to a single unit, allowing other units to continue operation and maintaining system redundancy
Solution Approach 2:
The control device performs preliminary determination of contactor failure states by comparing commanded states with actual states. This early detection enables the system to identify and isolate failed contactors before they can disable entire power conversion processing, allowing seamless switching to standby units
Data Source
AI summary
A power conversion device includes power conversion units connected to a shared power source. The power conversion units each include a contactor, a power converter, and a unit controller. A contactor controller closes or opens the contactor. A sensor measures a value of at least one of input current or output current of the power converter. The unit controller determines presence or absence of a failure of the power conversion units based on the measured value of the sensor, and sends a determination result to another unit controller.