Power Switch Fault Detection Circuit for DC Bus
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Solution Overview
Problem
Existing power conversion systems, particularly those with frequency converters, face challenges in detecting power switch faults efficiently, leading to potential system failures and increased costs due to the need for additional hardware and delayed detection of braking circuit failures.
Innovation Solution
A power switch fault detection method and circuit that continuously monitors the DC bus voltage, compares detection values with threshold values, and provides control signals to determine if the power switch is short-circuited or open-circuited, allowing for immediate fault detection and prevention of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional hardware is added to detect braking circuit failures, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The system uses its own existing voltage detection circuitry to monitor the DC bus voltage and detect power switch failures. The control unit analyzes voltage signals that already exist in the system without requiring separate detection hardware, making the system self-diagnostic and eliminating the need for additional detection components.
Solution Approach 2:
The voltage detection circuit and control unit serve multiple functions: they monitor DC bus voltage for power management and simultaneously detect power switch failures by analyzing voltage changes. This multi-functionality allows the same hardware to perform both normal operation control and fault detection, reducing the need for dedicated detection hardware.
2Measurement precision
If waiting for components to heat up to detect failures, then detection accuracy may be improved, but response time deteriorates
Solution Approach 1:
The system continuously monitors DC bus voltage and detects power switch failures immediately when they occur, without waiting for thermal effects to manifest. By detecting the electrical signature of a failed switch through voltage changes, the system responds in real-time rather than waiting for temperature-based indicators, significantly reducing response time while maintaining detection accuracy.
Data Source
AI summary
A fault detection method is used to determine whether a power switch coupled to a DC bus of a power conversion circuit is faulted. The method includes: detecting a bus voltage to provide a voltage signal and acquiring at least one detection value according to the voltage signal; providing control signals sequentially to turn off or turn on the power switch; determining that the power switch is a short-circuit fault if a first detection value is greater than or equal to a first threshold value when the power switch is turned off; determining that the power switch is an open-circuit fault if a second detection value is less than a second threshold value when the power switch is turned on; and providing an alarm signal or a disable signal when the power switch is the short-circuit fault or the open-circuit fault.