Half-Bridge Switch Driving for Bridge Short-Circuit Overvoltage Control
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Solution Overview
Problem
Power electronics systems in electric vehicles face challenges in detecting and managing bridge short circuits, leading to high short-circuit currents and overvoltages that can cause thermal destruction and semiconductor damage, making it difficult to ensure reliable short-circuit withstand strength.
Innovation Solution
A method is proposed where, upon detecting a bridge short circuit, the complementary topological switch is de-energized before switching off the short-circuit current, distributing the overvoltage and reducing the energy burden on the affected switch, thereby minimizing the risk of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the short-circuit current is switched off rapidly in the topological switch where bridge short circuit is detected, then the short-circuit current is reduced quickly, but a very high overvoltage is generated that may exceed the maximum voltage compatibility of the semiconductor
Solution Approach 1:
The complementary topological switch is de-energized in advance before the short-circuit current is switched off in the affected switch. This preliminary action ensures that when the overvoltage is generated during rapid current switching, the voltage is distributed across both switches, preventing excessive voltage on a single semiconductor device.
Solution Approach 2:
The complementary topological switch acts as an intermediary element that shares the overvoltage stress. By de-energizing this switch first, it becomes part of the voltage distribution path, effectively mediating the harmful overvoltage effect and protecting the semiconductor switches from exceeding their voltage compatibility limits.
2Loss of time
If the bridge short circuit is not detected in a timely manner, then the control response is slower, but the energy value increases very rapidly resulting in thermal destruction of the topological switch
Solution Approach 1:
The system continuously monitors the state of topological switches to detect bridge short circuits in real-time. When a short circuit is detected, the control system provides immediate feedback by de-energizing the complementary switch and subsequently switching off the short-circuit current, creating a rapid response loop that prevents thermal destruction.
Solution Approach 2:
Upon detecting a bridge short circuit, the system rushes through the protective actions without delay: first de-energizing the complementary switch, then immediately switching off the short-circuit current in the affected switch. This rapid sequence of actions minimizes the time the short-circuit current flows, preventing the energy value from increasing to destructive levels.
3Reliability
If the complementary topological switch is de-energized before switching off the short-circuit current, then the overvoltage is distributed and energy burden is reduced, but the control sequence becomes more complex
Solution Approach 1:
The protective control sequence is segmented into two distinct steps: first de-energizing the complementary topological switch, then switching off the short-circuit current in the affected switch. This segmentation of the control process allows for systematic management of the complex sequence, making it easier to implement and verify while achieving improved reliability.
Data Source
AI summary
A method for driving two mutually complementary topological switches of a half-bridge in a power module of an inverter includes detecting a bridge short circuit at one of the topological switches, de-energizing the topological switch complementary to the topological switch at which the bridge short circuit was detected, and, temporally switching off the short-circuit current in the topological switch at which the bridge short circuit was detected.