Drive Circuit Timing Control for Parallel IGBT and MOSFET Switching

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Solution Overview

Problem

Existing driving circuits for parallel-connected IGBT and MOSFET switching elements are silent on specific turn-on and turn-off timings, leading to higher switching losses due to simultaneous control, which results in inefficiencies and increased energy consumption.

Innovation Solution

A drive circuit that adjusts the turn-on and turn-off timings of IGBT and MOSFET switching elements by controlling the rate of electrical charge movement to minimize switching losses, with the IGBT turned on or off before the MOSFET, and vice versa, to prevent surge occurrences and optimize current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If simultaneous turn-on control is applied to parallel-connected IGBT and MOSFET, then switching operation is simplified, but switching loss increases

Engineering Contradiction:

Improvecontrol complexityVSAvoidswitching loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by turning on the IGBT before the MOSFET during switch-on operation. The IGBT is activated first to establish a current path, and then the MOSFET is turned on subsequently. This sequential approach prevents simultaneous conduction of both devices, thereby reducing switching losses while maintaining controlled operation complexity through a defined switching sequence.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If simultaneous turn-off control is applied to parallel-connected IGBT and MOSFET, then switching operation is simplified, but switching loss increases

Engineering Contradiction:

Improvecontrol complexityVSAvoidswitching loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by turning off the MOSFET before the IGBT during switch-off operation. The MOSFET is deactivated first to interrupt its current path, and then the IGBT is turned off subsequently. This sequential approach prevents simultaneous conduction of both devices during turn-off, thereby reducing switching losses while maintaining controlled operation complexity through a defined switching sequence.

Inventive Principle:

Principle #10Preliminary action

3Speed

If high rate of charge movement is applied to MOSFET, then switching speed is improved, but surge occurs when IGBT is still on

Engineering Contradiction:

Improveswitching speedVSAvoidsurge

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by ensuring the IGBT is turned off before initiating high-rate charge movement to the MOSFET gate. This sequencing prevents the MOSFET from switching at high speed while the IGBT is still conducting, thereby eliminating surge conditions. The MOSFET's fast switching capability is utilized only after the IGBT has been deactivated, resolving the contradiction between switching speed and surge prevention.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10291110B2Driving circuit for switching element and power conversion system

Publication Date: 2019.05.14 DENSO CORP

AI summary

In a drive circuit, a rate adjuster adjusts a charging speed of a MOSFET to be faster than the charging speed of an IGBT when a drive state changer changes the first switching element from the off state to the on state first, and changes the second switching element from the off state to the on state next. The rate adjuster also adjusts a discharging speed of the MOSFET to be faster than the discharging speed of the IGBT when the drive state changer changes the MOSFET from the on state to the off state first, and changes the IGBT from the on state to the off state next.