Bi-Cascode Four-Quadrant Switch for Low-Loss High-Voltage Power Flow
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Solution Overview
Problem
Existing power semiconductor switching devices for high-voltage applications suffer from high conduction losses due to the lack of a single device capable of bidirectional current conduction and voltage blocking for both polarities, leading to inefficiencies in configurations like four-quadrant switches.
Innovation Solution
A system comprising a normally-off four-quadrant power semiconductor switch coupled with normally-on junction field-effect transistors (JFETs) in a cascode configuration, utilizing wide bandgap semiconductor materials like silicon carbide (SiC) or aluminum gallium nitride/gallium nitride (AlGaN/GaN), and a bias circuit with Zener diodes and capacitors to minimize electrical losses and enhance semiconductor utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional power semiconductor switching devices are used for high-voltage applications, then the device can block voltage for both polarities and conduct current in both directions, but the conduction losses are high
Solution Approach 1:
The patent combines a normally-off 4Q switch with two normally-on JFETs in a cascode configuration to create a unified power switching device. This merging allows the normally-off switch to provide low conduction losses while the normally-on JFETs provide robust voltage blocking capability, resolving the contradiction between low energy loss and reliable voltage blocking.
Solution Approach 2:
The normally-on JFETs act as intermediary devices between the high-voltage source and the normally-off 4Q switch. They provide voltage blocking protection while allowing the low-loss normally-off switch to handle the power conduction, thus mediating between the conflicting requirements of low conduction losses and high voltage blocking reliability.
2Adaptability or versatility
If four-quadrant switches are made by combining multiple power electronic devices, then bidirectional current conduction and voltage blocking are achieved, but the device complexity increases
Solution Approach 1:
The normally-off 4Q switch provides multi-functionality by integrating bidirectional current conduction and voltage blocking capabilities in a single device. When combined with the normally-on JFETs, the overall system achieves universal bidirectional power flow control without requiring multiple separate switching devices, thus reducing system-level complexity while maintaining versatility.
3Reliability
If normally-on JFETs are used in cascode configuration, then voltage blocking capability is improved, but the switching losses increase
Solution Approach 1:
The patent applies local quality by using normally-on JFETs specifically for voltage blocking where high reliability is needed, while using the normally-off 4Q switch for power conduction where low losses are critical. The cascode configuration ensures that each device operates in its optimal region, with JFETs handling voltage stress and the 4Q switch handling current conduction, thus achieving both voltage blocking reliability and low switching losses.
Data Source
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AI summary
A system for providing bi-directional power flow and power conditioning for high-voltage applications. Said system comprising a normally-off four-quadrant power electronic switch having two gates and two normally-on junction field-effect transistor. The normally-off 4Q switch and the two normally-off JFETs are coupled to one another in a bi-cascode configuration.