H-Bridge Diagnostics for Inductive Load Short-Circuit Detection
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Solution Overview
Problem
Existing methods for detecting short circuits in inductive loads controlled by H-bridges are inadequate as they often fail to detect overcurrents simultaneously on both low-side and high-side currents, leading to incorrect anomaly identification.
Innovation Solution
A method that combines 'DIAG ON' and 'DIAG OFF' diagnostic techniques to detect anomalies in H-bridge power supply structures, involving multiple steps to measure currents, verify switch states, and discriminate between different types of anomalies to confirm short circuits at the inductive load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If DIAG ON diagnostic method is used to detect overcurrents, then anomaly detection capability is improved, but measurement precision deteriorates because overcurrents are not detected simultaneously on both low-side and high-side currents
Solution Approach 1:
The diagnostic process is divided into two separate diagnostic methods: DIAG ON for initial anomaly detection and DIAG OFF for precise overcurrent verification. This segmentation allows each method to specialize in its strength while compensating for the other's weaknesses.
Solution Approach 2:
DIAG ON is performed first as a preliminary screening to identify potential anomalies. Only when DIAG ON detects an anomaly does the system proceed to DIAG OFF for precise measurement, avoiding unnecessary precise measurements when no anomaly exists.
2Strength
If H-bridge components are stopped immediately upon detecting overcurrent on one current, then component safety is improved, but reliability deteriorates because it becomes impossible to determine the true type of anomaly
Solution Approach 1:
The system performs preliminary measurements during DIAG ON to identify potential anomalies before taking protective action. This allows the system to gather sufficient information about the anomaly type before stopping components, ensuring both safety and accurate diagnosis.
Solution Approach 2:
The system uses feedback from both DIAG ON and DIAG OFF measurements to continuously refine its understanding of the anomaly. The diagnostic results feed back into the control logic to determine the appropriate protective action, ensuring that components are stopped only when necessary and with accurate anomaly identification.
3Reliability
If multiple diagnostic steps are performed to ensure accurate anomaly identification, then reliability is improved, but productivity deteriorates due to increased diagnostic time
Solution Approach 1:
DIAG ON is executed first as a quick preliminary check to identify obvious anomalies. Only when DIAG ON detects an anomaly does the system proceed to the more time-consuming DIAG OFF measurements, minimizing unnecessary diagnostic time while maintaining high reliability.
Solution Approach 2:
The system performs partial diagnostics (DIAG ON only) in normal operation to maintain high productivity. Full diagnostics (DIAG OFF) are performed only when necessary, representing an excessive action only when required by the situation.
Data Source
AI summary
A method for supplying power to an inductive load (12) using an H-bridge (2) power supply structure, comprising a first block B1 of steps for detecting an anomaly using a “DIAG ON” diagnostic method, a second block B2 of steps for detecting an anomaly using a “DIAG OFF” diagnostic method, and finally a third block B3 of steps for discriminating the detected anomaly and for confirming a short circuit at the inductive load (12) anomaly.