Power Supply Failure Detection Using Segmented Strings
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Solution Overview
Problem
In power supply systems with multiple switching devices, early detection of failures is challenging due to the complexity of identifying which device has failed, especially when using MOSFETs, as current can flow through body diodes, making it difficult to distinguish between normal operation and failure.
Innovation Solution
A power supply system with a failure detector that connects battery modules to the main line to set a higher voltage, turns on all first switching devices and off all second switching devices, and checks if the voltage decreases to near 0V, and if not, determines a failure in the first switching device. Additionally, it sequentially turns off first switching devices and turns on second switching devices to detect stepwise voltage increases, identifying failures in both types of switching devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large number of switching devices are used in the power supply system, then the system can achieve higher power output and better performance, but it becomes difficult to detect and identify failures in individual switching devices
Solution Approach 1:
The power supply system is divided into multiple strings, with each string containing multiple sweep modules. This segmentation allows the failure detection function to operate at the string level rather than requiring individual device-level monitoring, thereby reducing the complexity of detecting failures in a large number of switching devices while maintaining high power output capability
Solution Approach 2:
A failure detector is introduced as an intermediary component that monitors the operational status of switching devices indirectly through voltage measurements. Instead of directly monitoring each switching device, the failure detector measures voltage across strings and sweep modules to infer the status of individual devices, simplifying the detection process in high-power systems with many switching devices
2Speed
If MOSFETs are used as switching devices to improve switching speed and efficiency, then power conversion performance is enhanced, but current can flow through body diodes making failure detection more difficult
Solution Approach 1:
The failure detector performs preliminary voltage measurements during normal operation to establish baseline values. When a failure occurs, the detector compares current voltage readings against these pre-established baselines, enabling early detection of MOSFET failures before they affect system performance. This preliminary monitoring approach works effectively even when current flows through body diodes during normal switching operation
3Reliability
If continuous monitoring of all switching devices is implemented to ensure safety, then failure detection capability is improved, but system complexity and cost increase
Solution Approach 1:
The failure detector is designed as a universal monitoring system that can detect failures in multiple switching devices within a string using a single detection mechanism. By measuring voltage across the entire string or sweep module, the system achieves multi-device monitoring capability without requiring individual sensors for each switching device, thereby maintaining high reliability while controlling system complexity
Solution Approach 2:
The switching devices and circuitry themselves provide the monitoring function through their inherent electrical characteristics. The failure detector utilizes the existing voltage and current paths in the power supply system to detect failures, rather than requiring separate dedicated monitoring circuits for each device. This self-service approach ensures safety through continuous monitoring while minimizing additional system complexity
Data Source
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AI summary
The present teaching provides a technique for detecting a failure in a switching device early in a power supply system including a plurality of sweep modules. A power supply system 1 disclosed here is connected to an electric power system through a distribution device. The power supply system includes a plurality of strings connected to the distribution device and a failure detector. The failure detector of the power supply system is configured to perform a first process of connecting at least one battery module to a main line to set a voltage detected by a string voltage detector at a voltage higher than a predetermined voltage in a state where a switch disconnects the distribution device and the main line, a second process of sending a disconnecting signal for disconnecting all the sweep modules from the main line, and a third process of determining whether the voltage detected by the string voltage detector is lower than the predetermined determination voltage or not after the second process.