Bidirectional Switch Circuit Reverse Conduction Without Drive Signal
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Solution Overview
Problem
Bidirectional switch circuits with antiparallel diodes or reverse blocking IGBTs become complex and incur high conduction loss due to increased parts and require intricate control to prevent damage from reverse voltage.
Innovation Solution
A bidirectional switch circuit design where one switching element conducts current in reverse direction without an on-drive signal, eliminating the need for freewheeling diodes and simplifying control by using a gate drive circuit with resistance material and gate-drain body diodes to manage voltage thresholds and prevent breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switching elements with antiparallel diodes are used to achieve bidirectional current conduction, then current can flow in both directions, but the number of parts increases and the circuit becomes complicated
Solution Approach 1:
The patent merges the functions of the switching element and the antiparallel diode into a single integrated structure. The body diode is formed within the switching element itself, eliminating the need for separate external diode components. This integration maintains bidirectional current conduction capability while significantly reducing circuit complexity and part count.
2Device complexity
If reverse blocking IGBTs are connected in antiparallel to reduce parts, then the circuit is simplified, but intricate control is required to prevent damage from reverse voltage
Solution Approach 1:
The switching element automatically responds to reverse voltage conditions without requiring external control signals. When reverse voltage is detected (source voltage higher than drain voltage), the element self-activates to conduct current in the reverse direction. This self-service mechanism eliminates the need for complex coordinated control of multiple switching elements while preventing damage from reverse voltage.
3Ease of operation
If switching elements are configured to conduct current in reverse direction without on-drive signal, then control is simplified and parts are reduced, but the switching element must inherently support reverse conduction
Solution Approach 1:
The switching element is designed with multi-functionality, serving both as a controlled switch and as a reverse-conducting device. The single switching element can operate in forward conduction mode when driven by gate signals and automatically switch to reverse conduction mode when reverse voltage is applied, eliminating the need for separate freewheeling diodes or complex control circuits.
Data Source
AI summary
A bidirectional switch circuit includes two switching elements connected to conduct a current in both directions. The two switching elements are connected in series to each other. Of the two switching elements, the switching element to which a reverse voltage is applied, a voltage of a source of one of the switching elements being higher than a voltage of a drain of the one, is configured to conduct a current from the source to the drain even when an on-drive signal is not being input to a gate terminal of the one.