Temperature Drift Resistant Clamp Circuit for IGBT Switching Loss Reduction

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Solution Overview

Problem

Existing power converter switching circuits face significant switching losses and reduced power output due to the need to operate below transistor operating limits to avoid damage from voltage variations caused by temperature drift in voltage clamp circuits.

Innovation Solution

A temperature drift resistant clamp circuit is introduced, utilizing zener diodes and temperature compensation circuits, or backwards diodes and temperature compensated voltage sources, to minimize the effects of temperature on voltage clamp operation, allowing the switching circuit to operate at higher voltages closer to the transistor's threshold without risking damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a voltage clamp circuit is used to limit peak voltage and protect transistors, then transistor reliability is improved, but the switching circuit must operate at voltage levels substantially below the operating limits, increasing turn off losses and reducing power output

Engineering Contradiction:

Improvetransistor reliabilityVSAvoidswitching losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the voltage parameter by using a temperature-compensated voltage reference that maintains a stable clamp voltage across temperature variations. This allows the switching circuit to operate closer to the transistor's maximum voltage rating without risking damage, thereby reducing switching losses while maintaining reliability protection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the simple RC-based voltage clamp with an electronic temperature-compensated reference system. This substitution uses electronic components (bandgap reference, operational amplifier) to actively compensate for temperature drift, enabling more precise voltage control and higher operating voltages

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If a simple RC voltage clamp circuit is used, then device complexity is reduced, but temperature drift causes wide variation in clamp voltage, forcing operation at lower voltages to avoid damage

Engineering Contradiction:

Improveclamp circuit complexityVSAvoidvoltage clamp precision

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces a temperature-compensated voltage reference as an intermediary between the power switching circuit and the clamp mechanism. This intermediary actively counteracts temperature drift effects, providing a stable reference voltage that ensures precise clamp operation across temperature ranges without excessive complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements feedback through an operational amplifier that continuously monitors the voltage across the switching device and compares it to the temperature-compensated reference. This feedback mechanism actively adjusts the clamp voltage to maintain precision despite temperature variations, improving reliability without prohibitive complexity

Inventive Principle:

Principle #23Feedback

3Loss of energy

If the switching circuit operates at higher voltages to reduce switching losses, then power output is improved, but the transistor may exceed operating limits and suffer damage from voltage variations

Engineering Contradiction:

Improveswitching lossesVSAvoidvoltage-induced damage

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent applies beforehand cushioning by implementing a proactive temperature-compensated voltage clamp that prevents voltage excursions before they can cause damage. The circuit is designed to anticipate and counteract temperature-induced voltage drift, cushioning the transistor against harmful voltage variations even as operation approaches maximum ratings

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution reduces switching losses and increases the power output of the power converter by enabling operation at higher voltages while maintaining safe operating conditions for the transistors, even under varying temperatures.

Implementation Method 1

the clamp circuit includes at least one zener diode

Methodology Applied

Scientific EffectZener breakdown: Avalanche Breakdown

Implementation Method 2

a temperature compensation circuit

Methodology Applied

Scientific EffectTemperature compensation:

Implementation Method 3

the clamp circuit includes a backwards diode component and a temperature compensated voltage source

Methodology Applied

Scientific EffectDiode reverse conduction: Diode

Data Source

PatentEP2546983B1Methods and systems for operating power converters

Publication Date: 2014.02.26 GENERAL ELECTRIC CO

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AI summary

A switching circuit (150) is provided. The switching circuit includes an insulated gate bipolar transistor (IGBT) (102) including a gate terminal (104), a collector terminal (106), and an emitter terminal (108), a gate drive circuit (114) electrically coupled to the gate terminal and configured to switch the IGBT on and off, and, a temperature drift resistant clamp circuit (152) electrically coupled between the gate terminal and the collector terminal of the IGBT, the temperature drift resistant clamp circuit configured to maintain a voltage at the collector terminal below a threshold voltage and facilitate reducing the effects of temperature on operation of the switching circuit.