Gate Drive Shutdown Sequence for SiC-MOSFET and Si-IGBT Heat Control
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Solution Overview
Problem
In power elements used in drive motors for home air conditioner compressors, the parallel connection of a SiC-MOSFET and a Si-IGBT leads to high heat generation when the gate voltage decreases, causing malfunction due to the SiC-MOSFET handling all current while the Si-IGBT is turned off.
Innovation Solution
A semiconductor device with a gate drive circuit that turns off both the first semiconductor switching element (Si-IGBT) and the second semiconductor switching element (SiC-MOSFET) when the first gate voltage is lower than a threshold, regardless of the input signal, to prevent excessive heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a protection circuit turns off the Si-IGBT when gate voltage decreases, then heat generation in Si-IGBT is suppressed, but all current flows into the SiC-MOSFET causing high heat generation and malfunction
Solution Approach 1:
The gate drive circuit preliminarily turns off the SiC-MOSFET before turning off the Si-IGBT when gate voltage decreases. This preliminary action prevents current from flowing into the SiC-MOSFET after the Si-IGBT is turned off, thereby avoiding high heat generation and malfunction in the SiC-MOSFET while still suppressing heat generation in the Si-IGBT
2Ease of manufacture
If the gate voltage applied to turn on the power element decreases, then cost is reduced, but the On-voltage increases causing deterioration of DC characteristics and increased loss
Solution Approach 1:
The gate drive circuit monitors the gate voltage and provides feedback control. When the gate voltage decreases to a threshold level, the circuit detects this condition and automatically turns off both the Si-IGBT and SiC-MOSFET, preventing operation in the high-loss region while still allowing cost-effective lower voltage operation when conditions permit
Data Source
AI summary
An object is to provide a technique that suppresses heat generation in a first semiconductor switching element and a second semiconductor switching element. A semiconductor device includes a gate drive circuit that drives each of the first semiconductor switching element and the second semiconductor switching element based on an input signal. When a first gate voltage applied to the first gate to turn On the first semiconductor switching element is lower than a first threshold, the gate drive circuit turns Off the first semiconductor switching element after turns Off the second semiconductor switching element regardless of the input signal.