Parallel RC-IGBT and WBG MOSFET Switching in Diode Mode
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Solution Overview
Problem
Wide bandgap semiconductor switches and silicon-based switches in parallel configurations face challenges in achieving low conduction losses and high switching performance, particularly in diode mode, due to differences in behavior between Si-based and wide bandgap semiconductor devices.
Innovation Solution
A semiconductor module comprising a reverse conducting IGBT and a wide bandgap MOSFET connected in parallel, with a gate controller managing gate signals to optimize switching by determining and applying specific gate signals for each device based on conduction start and end times, reducing conduction losses through differential gate voltage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a Si based IGBT and a wide bandgap MOSFET are connected in parallel to form a hybrid switch, then conduction losses are reduced and switching performance is improved, but control complexity increases due to different gate signal requirements
Solution Approach 1:
The gate signal for the wide bandgap MOSFET is dynamically adjusted based on the operating mode (diode mode or transistor mode). During diode mode, a first gate signal is applied, and during transistor mode, a second gate signal is applied, allowing the system to optimize performance for each mode while managing control complexity through mode-based differentiation.
Solution Approach 2:
The invention changes the gate signal parameters (voltage level, timing) of the wide bandgap MOSFET based on the operating conditions. By applying different gate signals during diode mode versus transistor mode, the system optimizes conduction losses and switching performance while adapting to the different behavioral characteristics of the hybrid switch combination.
2Loss of energy
If different gate signals are applied to the wide bandgap MOSFET during diode mode and transistor mode, then conduction losses are reduced, but the control system complexity increases
Solution Approach 1:
The control system determines the operating mode (diode mode or transistor mode) in advance and applies the appropriate gate signal accordingly. By predicting the mode of operation and preparing the corresponding gate signal, the system reduces conduction losses while managing control complexity through proactive mode-based control strategies.
3Productivity
If the wide bandgap MOSFET is operated in diode mode with optimized gate control, then switching performance is improved, but the device requires more complex timing control
Solution Approach 1:
The wide bandgap MOSFET's internal diode is utilized for reverse conduction, and the gate signal is timed to allow the diode to conduct during reverse current flow. This self-service approach leverages the inherent diode characteristic of the MOSFET to improve switching performance while reducing the need for complex external control circuitry.
Data Source
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AI summary
A semiconductor module (56) comprises reverse conducting IGBT (10, 10') connected in parallel with a wide bandgap MOSFET (32), wherein each of the reverse conducting IGBT (10, 10') and the wide bandgap MOSFET (32) comprises an internal ant-parallel diode (30, 48). A method for operating a semiconductor module (56) with the method comprising the steps of: determining a reverse conduction start time (tS), in which the semiconductor module (56) starts to conduct a current (IR) in a reverse direction, which reverse direction is a conducting direction of the internal anti-.parallel diodes (30, 48); applying a positive gate signal (VGS) to the wide bandgap MOSFET (32) after the reverse conduction start time (tS); determining a reverse conduction end time (tE) ) based on the reverse conduction start time (tS), in which the semiconductor module (56) ends to conduct a current (IR) in the reverse direction; and applying a reduced gate signal (VGS) to the wide bandgap MOSFET (32) a blanking time interval (tb) before the reverse conduction end time (tE), the reduced gate signal (VGS) being adapted for switching the wide bandgap MOSFET (32) into a blocking state.