Gate Driver Temperature Compensation for Switch Turn-Off
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Solution Overview
Problem
Solid state switches in electrified vehicles face challenges in operating efficiently across varying temperatures, leading to potential reverse voltage breakdown and increased costs due to the need for switches with higher breakdown voltages, which are not always available.
Innovation Solution
A gate driver system that adjusts the gate current based on the switch's temperature, limiting the operation of a resistive switch to a linear region during turn-off to reduce the rate of change of the drive current, thereby minimizing voltage stress and preventing breakdown, while also transitioning to a saturation region to increase the current rate when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gate driver increases the rate of change of drive current to improve switching speed, then productivity is improved, but voltage stress increases causing reverse voltage breakdown
Solution Approach 1:
The gate driver dynamically adjusts the gate resistance value based on temperature conditions. At low temperatures, a higher resistance is applied to limit di/dt and prevent voltage breakdown. At high temperatures, a lower resistance enables faster switching. This dynamic adaptation resolves the contradiction between switching speed and voltage stress by making the system flexible rather than fixed.
Solution Approach 2:
The invention changes the electrical parameter (gate resistance) based on temperature conditions. By modifying the resistance value, the rate of change of current (di/dt) is controlled to prevent voltage stress at low temperatures while allowing fast switching at high temperatures. This parameter change approach directly addresses the contradiction by adapting the system behavior to environmental conditions.
2Device complexity
If the gate driver uses a fixed gate resistance to simplify the circuit, then device complexity is reduced, but temperature adaptability deteriorates
Solution Approach 1:
The gate driver incorporates temperature feedback from the power semiconductor device and uses this information to automatically adjust the gate resistance. This feedback mechanism enables the circuit to adapt to temperature changes without requiring complex external control systems. The feedback approach maintains relatively simple circuitry while achieving excellent temperature adaptability.
Solution Approach 2:
The gate driver system monitors its own operating temperature and self-adjusts the gate resistance accordingly. This self-service capability allows the circuit to optimize its performance based on real-time conditions without external intervention. The system essentially regulates itself, maintaining simplicity while achieving adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces switching losses, enhances reliability, and allows the use of power devices with reduced voltage ratings, optimizing performance across a wide temperature range without additional sensing components, thus improving fuel economy and reducing costs.
Implementation Method 1
temperature feedback from the switch is used to adjust a gate current to change a rate of turn-off
Data Source
AI summary
A vehicle powertrain includes a switch configured to provide a drive current to an electric machine and coupled with a diode array and a gate driver. The gate driver may be configured to, in response to a voltage across the array exceeding a threshold while providing the drive current in a presence of a turn-off request, confine operation of a resistive switch to a linear region to decrease a rate of change of the drive current proportional to the voltage.