Semiconductor Device Inductance Reduction via Magnetic Plate

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Solution Overview

Problem

In power semiconductor modules, increased switching speed leads to element breakdown and noise due to overvoltage during turnoff operations, which is proportional to inductance and the time rate of change of current, and is exacerbated by high inductance, resulting in increased switching loss.

Innovation Solution

The semiconductor device design includes a configuration with first and second switching elements connected in series, an alternating-current electrode, and a magnetic plate to reduce mutual inductance by optimizing the placement and connection of these elements, thereby reducing inductance and suppressing overvoltage and switching loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If switching speed is increased, then productivity is improved, but overvoltage occurs causing element breakdown and noise

Engineering Contradiction:

Improveswitching speedVSAvoidelement breakdown

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent utilizes the harmful overvoltage phenomenon to beneficial effect by generating a compensating voltage through the auxiliary switching element and capacitor. The overvoltage that would normally cause element breakdown is converted into a useful function for suppressing reverse recovery current, thereby protecting the main switching element while maintaining high switching speed.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces an auxiliary switching element and capacitor as intermediary components between the power source and the main switching element. This intermediary circuit absorbs the harmful overvoltage and reverse recovery current, mediating the interaction between the high-speed switching operation and the power supply system, thereby preventing element breakdown.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If switching time is extended to suppress overvoltage, then reliability is improved, but switching loss increases

Engineering Contradiction:

Improveovervoltage suppressionVSAvoidswitching loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the conventional approach of suppressing overvoltage by extending switching time (temporal control) with an electrical circuit-based solution using auxiliary switching elements and capacitors. This substitution allows overvoltage suppression without compromising switching speed, thereby maintaining low switching loss while improving reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If inductance is reduced to suppress overvoltage, then harmful factors are reduced, but device complexity increases

Engineering Contradiction:

ImproveovervoltageVSAvoidmodule structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the auxiliary switching element and capacitor into the existing power semiconductor module structure, integrating them with the main switching element and power source. This merging approach reduces the need for separate external components and minimizes overall module complexity while effectively suppressing overvoltage through the combined circuit configuration.

Inventive Principle:

Principle #5Merging (Combining)

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 configuration effectively reduces inductance, suppresses element breakdown and noise, and minimizes switching loss by enhancing the cancellation of magnetic flux and uniformizing mutual inductance suppression.

Implementation Method 1

Methodology Applied

Scientific EffectMagnetic flux cancellation: Magnetic Field

Data Source

PatentUS9812411B2Semiconductor device, inverter circuit, and drive device

Publication Date: 2017.11.07 KK TOSHIBA

AI summary

A semiconductor device of an embodiment includes a first electrode, a second electrode facing the first electrode, an alternating-current electrode, a first switching element provided between the first electrode and the alternating-current electrode, and a second switching element provided between the second electrode and the alternating-current electrode. The first switching element and the second switching element are electrically connected in series between the first electrode and the second electrode, and the alternating-current electrode is electrically connected between the first switching element and the second switching element.