Digital Output Circuit Fault Detection via Monotonic Gate Drive
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Solution Overview
Problem
Industrial process control systems face challenges in providing flexible fault tolerance and efficiently testing digital output channels, particularly in detecting short circuit faults without requiring a minimum load current and protecting against over-voltage transients.
Innovation Solution
A method and apparatus that utilize a transistor-based output channel with a gate, source, and drain, driven by a gate drive signal, which includes a transient suppression module with avalanche diodes and a reverse blocking circuit, allowing for monotonically varying gate drive signals to test and monitor load voltage and current thresholds, and a processor-controlled driver to detect short circuit faults and ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fault tolerance methods like TMR or hot-standby modules are used, then system reliability is improved, but system cost and complexity increase
Solution Approach 1:
The output channel performs self-diagnostics by automatically testing its own switching elements through monotonically varying gate drive signals and monitoring load parameters. The system detects faults without requiring external test equipment or complex diagnostic hardware, enabling each channel to service itself and reduce overall system complexity while maintaining reliability
Solution Approach 2:
The system performs preliminary fault detection by continuously monitoring load voltage and current thresholds before faults propagate. The automatic testing mechanism detects potential failures in switching elements before they cause system-wide issues, allowing preventive maintenance and avoiding the need for complex reactive fault tolerance mechanisms
2Difficulty of detecting and measuring
If automatic testing of digital output channels is implemented, then fault detection capability is improved, but testing accuracy for short circuit faults deteriorates when minimum load current is not present
Solution Approach 1:
The testing mechanism changes the gate drive signal parameter monotonically from a starting value through a range of values, causing the output channel to transition through different operating states. This parameter variation enables the detection of short circuit faults even when load current is minimal, as the changing gate signal creates measurable variations in load voltage and current that reveal fault conditions
Solution Approach 2:
The system implements feedback by continuously monitoring load voltage and current during the gate drive signal variation. The monitored parameters are compared against expected ranges to detect short circuit faults, creating a closed-loop testing mechanism that maintains measurement precision regardless of minimum load current conditions
3Reliability
If digital output channels are protected from over-voltage transients, then system safety is improved, but device complexity increases
Solution Approach 1:
The system prepares for over-voltage transient protection by establishing monitored thresholds for load voltage and current before faults occur. The automatic testing mechanism creates a safety buffer by detecting abnormal voltage conditions early in the gate drive signal variation process, allowing preventive action before transients can cause damage, thus cushioning against potential failures without adding complex protection hardware
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
Enables flexible fault tolerance and accurate detection of short circuit faults in digital output channels, ensuring continuous operation and protecting against over-voltage transients, even when channels are de-energized or partially energized, thereby enhancing system reliability and safety.
Implementation Method 1
transient suppression module with avalanche diodes
Data Source
AI summary
A method and system for testing and protecting the operability of an output module. An output channel includes a transistor having a gate, a source, and a drain. The output channel drives a load with a load voltage and a load current in dependence upon a gate drive signal applied to the gate. The system determines a voltage threshold and a current threshold and monotonically varies the gate drive signal from a starting value for a predetermined time interval while monitoring the load current and the load voltage. The system returns the gate drive signal to the starting value if any of the load voltage reaches the voltage threshold, the load current reaches the current threshold, or a predetermined time interval expires indicating the condition of the output module.