Bi-cascode GaN Switch Reduces Conduction Loss

Solution Overview

Problem

Conventional fully controlled, four quadrant bidirectional switches suffer from high conduction loss and are limited to relatively low frequencies, making them inefficient for high-frequency applications.

Innovation Solution

A bi-cascode configuration using a normally-off field effect transistor (FET) pair and a dual-gate, normally-on bidirectional switch fabricated with wide bandgap semiconductor materials like AlGaN/GaN, which reduces conduction loss and increases operating frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional bidirectional switch configurations (two IGBTs in antiparallel with two diodes or two source-connected high-voltage MOSFETs) are used, then the switch can provide full control capability, but the conduction loss is high and the operating frequency is limited to less than 50 kHz

Engineering Contradiction:

Improveconduction lossVSAvoidoperating frequency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent changes the material parameter by using wide bandgap semiconductor materials (GaN, SiC) instead of conventional silicon materials. This material parameter change enables lower conduction loss and higher breakdown voltage, allowing operation at frequencies above 50 kHz while maintaining full bidirectional control capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite device structures combining different semiconductor materials with superior electrical properties. The bi-cascode configuration integrates multiple transistor types optimized for specific functions, creating a composite switch structure that achieves both low conduction loss and high-frequency operation

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional bidirectional switch configurations are used, then the switch can be implemented with standard components, but the conduction loss is high and efficiency is reduced

Engineering Contradiction:

Improvecomponent availabilityVSAvoidconduction loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent changes the material parameter by using wide bandgap semiconductor materials (GaN, SiC) instead of conventional silicon materials. This material parameter change enables lower conduction loss and higher breakdown voltage, allowing operation at frequencies above 50 kHz while maintaining full bidirectional control capability

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9130570B2Four quadrant bidirectional switch

Publication Date: 2015.09.08 ENPHASE ENERGY INC

AI summary

A four quadrant bidirectional switch. In one embodiment, the four quadrant bidirectional switch comprises a first switch, a second switch, and a third switch, wherein (i) the first and second switches are normally-off switches, (ii) the third switch is a dual-gate, bidirectional, normally-on switch, and (iii) the first, the second, and the third switches are coupled to one another in a bi-cascode configuration.