Wide Bandgap Semiconductor Module With Silicon Free Wheel Diode

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Solution Overview

Problem

Semiconductor modules using SiC Schottky barrier diodes as free wheel diodes experience high losses due to positive temperature characteristics, leading to restricted operation temperature ranges and inrush current values, as increased temperature and current result in positive feedback loops.

Innovation Solution

Incorporating a silicon-based free wheel diode with negative temperature characteristics, such as a Si PN or PiN diode, connected in antiparallel with a wide bandgap semiconductor switching element, to prevent positive feedback and reduce losses during inrush currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the temperature of the device rises due to increase in generated loss, then the forward voltage increases, but the generated loss further increases due to positive feedback

Engineering Contradiction:

Improvedevice temperatureVSAvoidgenerated loss

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The patent utilizes negative temperature characteristics of silicon-based free wheel diodes to create a negative feedback mechanism. As temperature rises, the forward voltage decreases, which reduces the generated loss and prevents the positive feedback loop that occurs with SiC Schottky barrier diodes.

Inventive Principle:

Principle #23Feedback

2Reliability

If a SiC-SBD is used as the free wheel diode, then high withstand voltage and low loss are achieved, but operation temperature range and inrush current value are restricted

Engineering Contradiction:

Improvewithstand voltage capabilityVSAvoidoperation temperature range and inrush current value

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent creates a composite semiconductor module structure combining wide bandgap semiconductor switching elements with silicon-based free wheel diodes. This composite approach leverages the high withstand voltage capability of wide bandgap materials while utilizing the negative temperature characteristics of silicon to expand the operational temperature range and inrush current tolerance.

Inventive Principle:

Principle #40Composite materials

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

The semiconductor module achieves high inrush-current tolerance and reduced losses by utilizing a silicon-based free wheel diode with negative temperature characteristics, preventing positive feedback and enhancing resistance to inrush currents.

Implementation Method 1

the free wheel diode is made of silicon and has negative temperature characteristics

Methodology Applied

Scientific EffectNegative temperature characteristics: Thermal Expansion

Data Source

PatentUS8823018B2Semiconductor module including a switching element formed of a wide bandgap semiconductor

Publication Date: 2014.09.02 MITSUBISHI ELECTRIC CORP

AI summary

Provided is a semiconductor module having high inrush-current tolerance. A semiconductor module includes a switching element formed of a wide bandgap semiconductor, and a free wheel diode connected in antiparallel with the switching element, wherein the free wheel diode is made of silicon and has negative temperature characteristics.