IGBT Overcurrent Protection via Parasitic Inductance Signal Correction
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Solution Overview
Problem
Existing driving circuits for electric vehicles face challenges in providing high current output while accurately monitoring overcurrent conditions, particularly due to parasitic inductance imbalances in parallel-connected IGBT switches, which can lead to premature overcurrent protection triggering and potential damage.
Innovation Solution
A driving circuit configuration that includes parallel-connected first and second switching devices, a current sensing circuit to generate a current sensing signal, a driver circuit to control switching operations, and an overcurrent protection circuit, along with a current sensing signal correction circuit to mitigate offset caused by parasitic inductance imbalance during switching transients, ensuring accurate overcurrent protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If parallel-connected IGBT switches are used to provide high current output, then the current output capability is improved, but parasitic inductance imbalance causes measurement precision deterioration
Solution Approach 1:
The patent introduces a current sensing signal correction circuit as an intermediary component between the current sensing circuit and the overcurrent protection circuit. This correction circuit specifically addresses the measurement errors caused by parasitic inductance imbalance in parallel-connected IGBT switches, thereby restoring measurement precision without compromising the high current output capability
Solution Approach 2:
The patent modifies the current sensing signal parameters by introducing correction signals that compensate for the offset caused by parasitic inductance imbalance. The correction circuit adjusts the sensing signal parameters during switching transients to eliminate measurement errors, enabling accurate overcurrent protection while maintaining high current output
2Measurement precision
If current sensing signal correction is applied during switching transient period, then overcurrent protection accuracy is improved, but device complexity increases
Solution Approach 1:
The correction circuit is designed to automatically activate during the switching transient period when parasitic inductance effects are most significant. By applying correction in advance during these critical moments, the system achieves accurate overcurrent protection without requiring continuous complex correction, thus balancing precision improvement with acceptable device complexity
Solution Approach 2:
The current sensing signal correction is applied periodically during switching transient periods rather than continuously. This periodic correction approach maintains overcurrent protection accuracy when needed while minimizing the operational burden and complexity of the correction circuit during steady-state operation
Data Source
AI summary
Circuits and methods for driving a load are disclosed. An exemplary driving circuit may include first and second switching devices electrically connected with each other in parallel. The driving circuit may also include a current sensing circuit configured to generate a current sensing signal indicating a value of a current flowing through the first switching device. The current sensing signal may include an offset caused by parasitic inductance imbalance in electrical connections connecting the first and second switching devices. The driving circuit may further include a driver circuit configured to control switching operations of the first and second switching devices. The driver circuit may include an overcurrent protection circuit electrically connected to the current sensing circuit. In addition, the driving circuit may include a current sensing signal correction circuit configured to reduce the offset in the current sensing signal received by the overcurrent protection circuit during a switching transient period.