Gate Driver Short Circuit Protection via Adaptive Turn-Off
Solution Overview
Problem
Conventional gate drivers for solid state switches in electrified vehicles face challenges in managing high current and voltage conditions, leading to voltage spikes during switch-off, which can cause stress and potential damage to semiconductor devices, especially during short circuit conditions.
Innovation Solution
A gate driver system that outputs a fast turn-off signal when the load current is below a threshold, latches a soft turn-off signal when the current exceeds the threshold for a defined period, and inhibits the fast turn-off signal if a turn-off request is received before the mask timer expires, enabling a soft turn-off mode to reduce voltage spikes and protect the switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fast turn-off signal is used to improve switching speed and productivity, then the switching performance is improved, but voltage spikes occur during switch-off which can cause stress and potential damage to semiconductor devices
Solution Approach 1:
The gate driver dynamically adjusts the turn-off signal characteristics based on real-time current detection. When overcurrent is detected, the system transitions from a fast turn-off mode to a soft turn-off mode, making the switching behavior adaptive to operating conditions rather than fixed
Solution Approach 2:
The system implements current feedback by detecting the load current and using this information to control the gate driver behavior. The feedback mechanism triggers a latch signal when overcurrent is detected, which then modifies the gate drive signal to prevent voltage spikes
2Reliability
If a soft turn-off mode is used to reduce voltage spikes and protect semiconductor devices, then device protection is improved, but the switching speed and productivity are reduced
Solution Approach 1:
The gate driver dynamically adjusts the turn-off signal characteristics based on real-time current detection. When overcurrent is detected, the system transitions from a fast turn-off mode to a soft turn-off mode, making the switching behavior adaptive to operating conditions rather than fixed
Solution Approach 2:
The soft turn-off mode is applied selectively only when overcurrent conditions are detected, rather than being continuously applied. This partial application of soft turn-off prevents voltage spikes during critical conditions while maintaining fast switching during normal operation
3Reliability
If current detection and latch logic are added to implement soft turn-off protection, then device protection is improved, but the gate driver complexity increases
Solution Approach 1:
The current detection circuit, latch logic, and gate driver functions are merged into a single integrated device. This consolidation provides comprehensive short circuit protection while avoiding the complexity of separate discrete components for each function
Data Source
AI summary
A vehicle includes an electric machine configured to provide propulsive force to the vehicle, and a power inverter configured to supply power from a traction battery to the electric machine using a first and second switch configured as a half-bridge, wherein the first switch is controlled by a gate driver. The gate driver is configured to operate in a soft turn-off mode when a load current exceeds a threshold for a time period defined by a mask timer, operate in a fast turn-off mode when the load current is below the threshold, and in response to a turn-off request received prior to expiration of the mask timer after the load current exceeds the threshold, enable the soft turn-off mode.