Power Switch Gate Drive Circuit for Integrator-Free Short-Circuit Detection

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Solution Overview

Problem

Existing drive devices for power semiconductor elements require a detection device that uses an integrator to detect gate charges, resulting in a larger circuit scale.

Innovation Solution

A drive device that includes a capacitor connected in parallel to a first voltage source with a switching element interposed, a switching device between the capacitor and the gate terminal, and comparison devices to determine the short-circuited state based on capacitor voltage and gate voltage comparisons, eliminating the need for an integrator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an integrator is used to detect gate charges, then short circuit detection capability is improved, but circuit scale increases

Engineering Contradiction:

Improveshort circuit detection capabilityVSAvoidcircuit scale

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the integration function from a dedicated integrator circuit and implements it using the inherent capacitance of existing circuit elements (gate capacitance and parasitic capacitances). This removes the need for a separate integrator component while preserving the gate charge detection capability, thereby reducing circuit scale without sacrificing short circuit detection reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent makes existing circuit elements serve multiple functions: the gate capacitance and parasitic capacitances that normally just store charge are now used to perform integration of gate current. This multi-functionality eliminates the need for dedicated integrator hardware, reducing overall circuit complexity while maintaining detection capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables determination of a short circuit in a power semiconductor element with a simplified circuit, reducing the circuit scale and improving efficiency.

Implementation Method 1

a capacitor connected in parallel to a first voltage source with a switching element interposed

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a first comparison device to output a signal indicating a result of comparison between a voltage of the capacitor and a first reference value, a second comparison device to output a signal indicating a result of comparison between a voltage or a derivative value of the voltage at the gate terminal and a second reference value

Methodology Applied

Scientific EffectVoltage comparison:

Data Source

PatentUS12206401B2Drive device to drive semiconductor element, semiconductor device, and power conversion device

Publication Date: 2025.01.21 MITSUBISHI ELECTRIC CORP

AI summary

A semiconductor device includes a power switching element and a drive device to drive the power switching element. The drive device includes a voltage source, a switching element, a capacitor connected in parallel to the voltage source with the switching element being interposed, a switching element provided between the capacitor and a gate terminal of the power switching element, a first comparison device to output a result of comparison between a voltage of the capacitor and a reference value VQR, a second comparison device to output a result of comparison between a gate voltage of the power switching element and a reference value VR, and a short-circuit determination unit that makes determination as to a short circuit of the power switching element based on an output signal from the first comparison device and an output signal from the second comparison device.