Power Supply Switch Control for Back-EMF Short Detection
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Solution Overview
Problem
Conventional power supply controllers fail to effectively detect short-circuit anomalies in semiconductor switching elements, leading to false detection issues due to electromotive forces generated by motors, which can result in improper operation and safety concerns.
Innovation Solution
A power supply controller with a control circuit, first and second determination circuits, and a short detecting circuit that differentiate between short anomalies and electromotive forces by using threshold voltage settings and voltage subtraction methods to accurately determine the state of the semiconductor switching element, preventing false detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current detecting resistor is used to detect overcurrent, then overcurrent protection is achieved, but short-circuit anomalies in the semiconductor switching element cannot be detected
Solution Approach 1:
The detection function is segmented into two independent circuits: a current detecting resistor for overcurrent detection and a voltage detecting circuit for short-circuit detection. This segmentation allows each circuit to specialize in detecting specific anomaly types without interfering with the other, resolving the contradiction between overcurrent protection and short-circuit detection capability
Solution Approach 2:
The voltage detecting circuit acts as an intermediary mechanism that indirectly detects short-circuits by monitoring voltage changes across the semiconductor switching element. This intermediary approach enables short-circuit detection without requiring direct modification of the current detection path, maintaining both overcurrent and short-circuit detection capabilities
2Measurement precision
If voltage threshold detection is used to identify short anomalies, then accurate short-circuit detection is achieved, but false detection occurs due to electromotive forces from motor inertia
Solution Approach 1:
The detection system dynamically adjusts the voltage threshold based on the operational state of the load. When the load is in a state where electromotive force generation is expected (e.g., motor deceleration), the threshold is adjusted to prevent false detection. This dynamic adaptation resolves the contradiction between detection accuracy and false alarm rate
Solution Approach 2:
The system incorporates feedback mechanisms that monitor the operational context and adjust detection parameters accordingly. By feeding back information about load state and electromotive force conditions, the system can distinguish between genuine short anomalies and voltage spikes caused by motor inertia, eliminating false alarms while maintaining detection accuracy
Data Source
AI summary
A power supply controller includes a semiconductor switching element disposed on a current supply line from a power source to a load. The semiconductor switching element is switched between ON and OFF for controlling power supply to the load. A short anomaly of the semiconductor switching element is determined if at least one of an input-to-output voltage of the semiconductor switching element being smaller than a first threshold and the semiconductor switching element being in an ON state is detected, when an OFF signal for instruction to turn OFF the semiconductor switching element is received.