Reverse Conducting IGBT Gate Control for Reverse Recovery Losses
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Solution Overview
Problem
Reverse recovery losses in reverse conducting IGBTs occur when switching from reverse biased to forward biased mode, as the charge carrier plasma in the drift region needs to be removed, leading to significant energy losses.
Innovation Solution
The semiconductor device incorporates a design where the gate terminal is driven to create a conducting channel in the body region between the source and drift regions before switching to the forward biased mode, reducing the concentration of stored charge carriers and minimizing reverse recovery losses by transitioning to a unipolar operation mode, where only electrons or a low concentration of holes are injected into the drift region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the RC-IGBT operates in reverse biased mode like a diode, then current conduction is achieved, but reverse-recovery losses occur when switching to forward-biased mode
Solution Approach 1:
The patent applies preliminary action by activating the gate terminal before the RC-IGBT switches from reverse biased to forward biased mode. This preliminary gate activation creates a conducting channel that facilitates the removal of charge carriers from the drift region, thereby reducing reverse-recovery losses. The gate signal is applied in advance to prepare the device for efficient switching transition.
2Loss of energy
If the body diode conducts in reverse biased mode, then current flows, but significant charge carrier plasma accumulates in the drift region requiring removal
Solution Approach 1:
The patent employs feedback control by monitoring the state of the RC-IGBT and adjusting the gate terminal signal accordingly. When the device transitions from reverse biased to forward biased mode, the feedback mechanism triggers gate activation to manage charge carrier removal. This closed-loop control ensures optimal timing and magnitude of gate signal to minimize energy losses associated with charge carrier plasma removal.
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 reverse recovery losses by minimizing the charge carriers that need to be removed from the drift region before the device blocks, thereby enhancing the switching efficiency and reducing energy losses in the IGBT.
Implementation Method 1
the gate terminal is driven to create a conducting channel in the body region between the source and drift regions
Implementation Method 2
the RC-IGBT operates like a diode that may cause reverse-recovery losses when the RC-IGBT switches from the reverse biased mode, which is when the body diode is conducting
Data Source
AI summary
According to an embodiment of a method, a semiconductor device is operated in a reverse biased unipolar mode before operating the semiconductor device in an off-state in a forward biased mode. The semiconductor device includes at least one floating parasitic region disposed outside a cell region of the device.