RB-IGBT Bidirectional Switch Leakage Control
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Solution Overview
Problem
Reverse-blocking insulated gate bipolar transistors (RB-IGBTs) experience increased leakage current when a reverse voltage is applied, leading to higher losses and reduced reliability and efficiency in power conversion devices.
Innovation Solution
A power conversion device is designed with a bidirectional switch formed by connecting two reverse-blocking insulated gate bipolar transistors in reverse parallel, where the control circuit generates gate drive signals to bring the gates of the RB-IGBTs into an on state when a reverse voltage is applied, thereby suppressing the increase in leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If reverse-blocking insulated gate bipolar transistors are used in a bidirectional switch, then low loss characteristics are achieved, but leakage current increases when reverse voltage is applied
Solution Approach 1:
The patent applies the inversion principle by reversing the conventional gate signal strategy. Instead of turning off the RB-IGBT when reverse voltage is applied (conventional approach), the patent turns on the gate signal specifically when reverse voltage is detected. This inverted approach suppresses leakage current by maintaining the transistor in an active state with proper gate control, rather than allowing it to enter an uncontrolled off-state with high leakage.
Solution Approach 2:
The patent changes the gate voltage parameter dynamically based on the polarity of the collector-emitter voltage. When reverse voltage is detected (Vce < 0), the gate voltage is adjusted to a specific level that suppresses leakage current. This parameter change approach allows the transistor to operate optimally under different voltage conditions, maintaining low loss characteristics while preventing excessive leakage.
2Reliability
If gate drive signals are given to RB-IGBTs under reverse voltage, then leakage current is suppressed, but control circuit complexity increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the collector-emitter voltage polarity and using this information to control the gate drive signal. The control circuit detects when reverse voltage is applied to the RB-IGBT and automatically adjusts the gate signal accordingly. This closed-loop feedback mechanism simplifies the control strategy compared to complex predictive control, as it directly responds to the actual voltage condition.
Solution Approach 2:
The control circuit performs self-service by autonomously detecting the voltage polarity and generating the appropriate gate drive signal without requiring external intervention or complex coordination with other circuit elements. The RB-IGBT essentially controls its own gate signal based on its operating conditions, reducing the burden on the overall control system.
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 effectively reduces losses due to leakage current, enhances the reliability of RB-IGBTs, and improves the conversion efficiency of the power conversion device by preventing hole reinjection and minimizing leakage current.
Implementation Method 1
reverse-blocking insulated gate bipolar transistor is such that the size of leakage current when an on signal is given to the gate in a condition in which a reverse voltage is applied between the collector and emitter differs from the size of leakage current when an off signal is given to the gate in the same condition
Implementation Method 2
gate drive signals generated based on command signals output from a control circuit are given one to each of the reverse-blocking insulated gate bipolar transistors
Implementation Method 3
bidirectional switch formed by connecting two reverse-blocking insulated gate bipolar transistors, having reverse breakdown voltage characteristics, in reverse parallel
Data Source
AI summary
An increase in leakage current when a reverse voltage is applied to reverse-blocking insulated gate bipolar transistors is suppressed, thus reducing a loss resulting from the leakage current. A power conversion device includes a bidirectional switch formed by connecting two reverse-blocking insulated gate bipolar transistors having reverse breakdown voltage characteristics in reverse parallel. A control circuit is configured so as to output command signals for bringing the gates of the reverse-blocking insulated gate bipolar transistors, to which a reverse voltage is applied, into an on state.