Switching Element Drive Circuit Abnormal State Detection
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Solution Overview
Problem
Existing electronic devices with switching elements and drive circuits, such as power converters, face issues with abnormal states where the switching element cannot be turned off despite a drive signal instructing turn-off, leading to potential heat generation and thermal destruction due to faults in IGBTs or MOSFETs.
Innovation Solution
An electronic device with a first switching element and a first drive circuit that controls the voltage on its control terminal to detect abnormal states by determining if a current is flowing through the switching element despite a turn-off signal, using current detection circuits to deactivate the drive power supply and ensure the switching element is turned off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a switching element (IGBT/MOSFET) is used in a power converter, then power conversion and control functionality is achieved, but the risk of abnormal states increases where the switching element cannot be turned off despite control signals, leading to heat generation and potential thermal destruction
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors the on/off state of the switching element and compares it with the control signal. When a discrepancy is detected (abnormal state where switching element remains on despite turn-off signal), the control circuit activates a discharge circuit to forcibly discharge the gate terminal, ensuring the switching element turns off. This feedback loop prevents thermal destruction and enhances reliability while maintaining power conversion functionality.
2Reliability
If the gate voltage is continuously monitored to detect abnormal states, then early detection of switching element faults is achieved, but additional detection circuits and complexity are required
Solution Approach 1:
The patent employs a self-service detection mechanism where the control circuit utilizes existing control signals and switching element state information to detect abnormal conditions. The control circuit determines whether the switching element is in an abnormal state by comparing its actual state with the intended state from control signals, without requiring separate complex detection circuits. This approach achieves reliable abnormal state detection while minimizing additional circuit complexity.
3Reliability
If a discharge circuit is activated to forcibly turn off the switching element in abnormal states, then thermal destruction is prevented, but additional circuit components and potential interference with normal operation are introduced
Solution Approach 1:
The patent incorporates a preliminary discharge circuit that is pre-configured and ready to activate when abnormal states are detected. The discharge circuit includes a discharge transistor and discharge capacitor connected to the gate terminal, positioned in advance to provide immediate forced turn-off capability. This preliminary arrangement ensures rapid response to abnormal conditions, preventing thermal destruction while integrating smoothly with the existing drive circuit without requiring complex additional components.
Data Source
AI summary
An electronic device that is capable of detecting an abnormal state such that a switching element is unable to be turned off in spite of a drive signal instructing turn-off of the switching element. The device includes a switching element that is driven by controlling a voltage on its control terminal, a drive circuit that controls the voltage on the control terminal of the switching element on the basis on an inputted drive signal to drive the switching element. In cases where there exists a current flowing through the switching element in spite of the drive signal instructing turn-off of the switching element, the drive circuit determines that the switching element is in an abnormal state, and cuts off supply of voltage from a drive power supply circuit to the control terminal of the switching element to thereby turn off the switching element.