Power Supply Fault Detection via Input Current Moving Average
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Solution Overview
Problem
Existing power supply systems face challenges in detecting and mitigating overcurrent conditions, particularly when the absolute current draw is below the maximum rating, leading to potential damage or failure due to faults like shorts, as conventional countermeasures like fuses may not trigger until significant damage is done.
Innovation Solution
The implementation of a fault detection system that monitors the rate of change of input current using a moving average, identifying current spikes indicative of faults, and triggering protective measures such as shutting down the power supply, even if the absolute current is within the rated capacity, in conjunction with additional fault detection conditions like PFC fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional countermeasures like fuses are used to detect overcurrent conditions, then the system can protect against extreme overcurrent, but the fuse may not trigger until significant damage is done when the current is below the maximum rating
Solution Approach 1:
The system performs preliminary action by continuously monitoring the rate of change of input current using a moving average calculation before damage occurs. The controller calculates the moving average of the input current and compares it with the instantaneous current to detect current spikes indicative of faults, enabling early fault detection before significant damage happens.
Solution Approach 2:
The patent replaces the mechanical fuse system with an electronic monitoring system. Instead of relying on a mechanical fuse to blow when current exceeds a threshold, the system uses a controller to electronically monitor the rate of change of input current, calculate moving averages, and trigger protective measures through electronic control, enabling much faster and more sensitive fault detection.
2Reliability
If the system shuts down immediately upon detecting a current spike, then fault prevention is improved, but false positives increase
Solution Approach 1:
The system uses feedback by continuously monitoring the input current, calculating the moving average, comparing the instantaneous current with the moving average, and adjusting its operation based on this comparison. The controller incorporates feedback loops that monitor multiple conditions (current rate of change, absolute current level, PFC status) and only trigger shutdown when multiple feedback conditions are satisfied, reducing false positives while maintaining fault prevention capability.
3Measurement precision
If expensive countermeasures like e-fuses are used to improve fault detection, then detection precision is improved, but device cost increases
Solution Approach 1:
The patent employs cheap short-living objects by using readily available, low-cost components such as standard current sensors, microprocessors, and moving average calculation algorithms. Instead of using expensive specialized protection devices like e-fuses, the system uses inexpensive general-purpose computing resources to perform the fault detection function, achieving high measurement precision at low cost.
Solution Approach 2:
The system implements self-service by using the power supply's own controller and existing sensing capabilities to perform fault detection. The controller that already manages the power supply operation also calculates the moving average of input current and makes protection decisions, eliminating the need for separate expensive protection circuits or external monitoring devices.
Data Source
AI summary
An example power supply for supplying electrical power to an electronic device includes converters to convert an input power signal into an output power signal, and a controller. The controller is to periodically measure an input current being drawn from the input power signal, periodically determine a moving average of the input current, and periodically compare the moving average of the input current to the present input current. The controller identifies that a fault may have occurred in response to the present input current exceeding the moving average by a threshold amount. The controller shuts down supply of power to the electronic device responsive to identifying the fault.