Inductive Load Control Circuit Fault Detection via Current Comparison
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Solution Overview
Problem
Existing methods for checking control circuits of inductive loads are inadequate in identifying faults, particularly in recirculation transistors and pulse-width-modulation logic, and cannot effectively monitor the control circuit during active valve test pulses or when the load is completely switched off.
Innovation Solution
A method involving switching on the driver transistor for a checking period, measuring the current, then switching on the recirculation transistor and measuring the current again to identify faults by comparing the two currents, allowing for the detection of deviations that indicate fault states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing fault checking methods are used, then the control circuit can be monitored during normal operation, but faults in recirculation transistors and pulse-width-modulation logic cannot be identified
Solution Approach 1:
The patent applies preliminary action by performing a dedicated checking phase before normal operation where the driver transistor and recirculation transistor are sequentially activated and tested. This preliminary checking identifies potential faults in the recirculation transistor and PWM logic before they affect normal operation, enabling proactive fault detection that existing methods miss.
Solution Approach 2:
The patent introduces an intermediary checking mechanism that uses current measurements as a mediator to indirectly assess the health of the recirculation transistor and PWM logic. By measuring currents during controlled activation phases and comparing them against expected values, the system can identify faults without directly testing the problematic components, thus solving the detection difficulty.
2Ease of operation
If the control circuit is checked during active valve test pulses or when the load is completely switched off, then monitoring can be performed, but fault identification is ineffective
Solution Approach 1:
The patent segments the monitoring process into distinct phases: a dedicated checking phase where the driver transistor is activated and current measurements are taken, followed by activation of the recirculation transistor for additional measurements. This segmentation allows precise fault detection during specific operational states rather than attempting continuous monitoring during all states, thereby improving measurement precision while maintaining operational ease.
Solution Approach 2:
The patent implements periodic action by cyclically alternating between checking phases and normal operation phases. During each checking phase, specific transistors are activated and currents are measured to detect faults. This periodic checking ensures fault detection capability is maintained without requiring continuous monitoring during all operational states, resolving the contradiction between monitoring availability and detection accuracy.
3Device complexity
If current measurement is performed only during on phase or off phase separately, then simple measurement is possible, but comprehensive fault detection is achieved
Solution Approach 1:
The patent merges the checking function with the existing PWM operation by integrating current measurements during controlled activation of both the driver transistor and recirculation transistor. Instead of adding separate complex measurement systems, the invention combines fault checking with normal operational current measurements, maintaining device simplicity while achieving comprehensive fault detection coverage through strategic measurement timing and comparison.
Data Source
AI summary
A method for checking a control circuit for an inductive load, wherein one or two currents are measured and evaluated. An arrangement for carrying out such a method is also disclosed.