Half-Bridge MOSFET Circuit for Reverse Recovery Current Reduction

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Solution Overview

Problem

Existing half-bridge circuits suffer from significant reverse recovery currents, which lead to switching losses, and existing solutions have not adequately addressed this issue.

Innovation Solution

A half-bridge circuit configuration comprising series-connected high-voltage and low-voltage MOSFETs with synchronized switching and a capacitor, where the high-voltage MOSFETs have a drain-to-source withstanding voltage 10 times greater than the low-voltage MOSFETs, and a capacitor voltage 10 times greater than the low-voltage MOSFETs, to manage and reduce reverse recovery currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional half-bridge circuit configuration is used, then circuit simplicity is maintained, but reverse recovery current is significant causing switching losses

Engineering Contradiction:

Improveswitching lossVSAvoidcircuit complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent divides each switching circuit into a series connection of high-voltage MOS and low-voltage MOS, creating segmented switching circuits that can independently control voltage blocking and current switching functions, thereby reducing reverse recovery current while maintaining manageable circuit complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The capacitor connected between the drain of the first high-voltage MOS and source of the second low-voltage MOS acts as an intermediary element that manages voltage transitions and reduces reverse recovery current during switching operations

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If high-voltage MOS and low-voltage MOS are connected in series with synchronized switching, then reverse recovery current is reduced, but device voltage requirements increase

Engineering Contradiction:

Improvereverse recovery currentVSAvoidvoltage withstanding capability

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

The voltage blocking function is segmented between high-voltage MOS and low-voltage MOS devices, where high-voltage MOS handles the majority of voltage blocking while low-voltage MOS assists in current switching, reducing reverse recovery current without requiring a single high-voltage device to handle all functions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent specifies that the drain-to-source withstanding voltage of high-voltage MOS should be 10 times or greater than that of low-voltage MOS, and the capacitor voltage should be greater than 300V and 10 times or greater than the low-voltage MOS drain-to-source withstanding voltage, optimizing the voltage distribution to minimize reverse recovery current

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12512835B2Half-bridge circuit and power supply device

Publication Date: 2025.12.30 SHARP KK

AI summary

A half-bridge circuit includes a series of a first high-voltage MOS, a first low-voltage MOS, a second high-voltage MOS, and a second low-voltage MOS. The half-bridge circuit further includes a capacitor, and the capacitor is connected to the first high-voltage MOS and the second low-voltage MOS. The voltage of the capacitor is greater than 300 V. The drain-to-source withstanding voltage of the first high-voltage MOS is higher than the drain-to-source withstanding voltage of the first low-voltage MOS by 10 times or greater. The voltage of the capacitor is higher than the drain-to-source withstanding voltage of the first low-voltage MOS by 10 times or greater.