H-Bridge Short Circuit Detection Without Inductive Load Drift
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Solution Overview
Problem
Existing methods for detecting short circuits in H-bridge structures coupled to inductive loads are inadequate, particularly in distinguishing between short circuits at the output or in the inductive load, and can lead to erroneous conclusions, especially in cases of intermittent faults, without accurately determining the origin without moving the inductive load.
Innovation Solution
A method involving an H-bridge switching structure with specific switch configurations and current measurement techniques that allow for the detection of short circuits without moving the inductive load, by identifying the switch causing the anomaly and determining its origin through controlled power supply and freewheeling states, enabling discrimination between short circuits in the H-bridge and the inductive load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reverse current is applied to detect short circuit in inductive load, then short circuit detection capability is improved, but inductive load drifts which may be detrimental
Solution Approach 1:
The patent applies preliminary action by performing short circuit detection before the inductive load drifts occur. The method detects short circuits during normal operation or before applying reverse current, using current measurements taken during the supply phase and freewheeling phase to identify short circuits before they cause load drift or damage.
Solution Approach 2:
The patent uses an intermediary approach by introducing a detection method that operates through the existing H-bridge switching structure and current measurements without requiring direct reverse current application to the load. The control unit acts as an intermediary, analyzing current patterns during normal switching operations to infer short circuit conditions.
2Device complexity
If simple current measurement at each transistor is used, then detection simplicity is improved, but ability to distinguish short circuit origin deteriorates
Solution Approach 1:
The patent applies periodic action by utilizing the regular PWM switching cycles of the H-bridge to perform repeated current measurements. The control unit measures current at specific phases (supply phase and freewheeling phase) of each PWM cycle, allowing it to detect and distinguish short circuit conditions through pattern recognition over multiple periodic cycles without adding complex hardware.
Solution Approach 2:
The patent uses dynamics by analyzing the temporal behavior of current measurements during different phases of the switching cycle. The control unit dynamically evaluates current patterns during supply phase versus freewheeling phase to determine the origin of short circuits, transforming a static measurement problem into a dynamic analysis that leverages the time-varying nature of the switching operation.
3Reliability
If reverse current detection method is used, then short circuit detection is improved, but execution time increases due to additional detection steps
Solution Approach 1:
The patent applies continuity of useful action by performing short circuit detection continuously during normal operation without interrupting the power supply to the inductive load. The current measurements are taken during the regular supply and freewheeling phases of each PWM cycle, allowing detection to occur continuously as part of the normal operation rather than requiring separate detection intervals or reverse current applications.
Data Source
AI summary
A method for supplying power to an inductive load including an H-bridge switching structure coupled to a power supply and including a first, a second, a third and a fourth switch and current measurement means designed to measure a current through each switch, the power supply method including: a) supplying power to the inductive load, b) reducing an accumulated current in the inductive load. Upon detection of an anomaly: c) identifying the switch that caused a circuit break, d) identifying whether the anomaly was detected during step a) or step b). If an anomaly is detected in step a): e) performing step b) for a third duration, f) identifying the origin of the anomaly, g) if an anomaly is detected in step b): h) identifying the origin of the anomaly.