Gate Charge Short-Circuit Detection in Power Semiconductor Drives

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Solution Overview

Problem

Existing drive control circuits for power semiconductor elements face challenges in detecting arm short circuits quickly and efficiently, leading to potential thermal destruction due to high current flow, and require larger circuit sizes to achieve fast detection.

Innovation Solution

A drive control circuit that includes a driver, gate current detector, gate charge amount calculator, and short-circuit detector with logical operation circuitry to compare gate current and charge amounts with reference values, allowing for fast and reliable short-circuit detection without increasing circuit size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If voltage across primary terminals is detected to identify short-circuit state, then short-circuit detection can be performed, but detection period must be set which prevents fast detection

Engineering Contradiction:

Improveshort-circuit detection capabilityVSAvoiddetection speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent changes the detection parameter from voltage across primary terminals to gate charge amount. By integrating gate current over time to obtain gate charge amount and comparing it with a predetermined threshold, the system achieves fast short-circuit detection without requiring a detection period, thus resolving the contradiction between detection capability and detection speed.

Inventive Principle:

Principle #35Parameter changes

2Speed

If gate voltage and gate current are detected to exploit gate charge characteristics for fast short-circuit detection, then fast detection is achieved, but circuit size increases

Engineering Contradiction:

Improveshort-circuit detection speedVSAvoidcircuit size

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent extracts only the essential element needed for fast detection - the gate charge amount obtained by integrating gate current. By focusing solely on gate charge characteristics rather than simultaneously detecting both gate voltage and gate current, the circuit size is reduced while maintaining fast detection capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The gate charge amount calculation serves multiple functions: it characterizes the switching state of the power semiconductor element, enables fast short-circuit detection, and provides information about the switching process. This multi-functionality reduces the need for separate detection circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12149240B2Drive control circuit for power semiconductor element, power semiconductor module, and power converter

Publication Date: 2024.11.19 MITSUBISHI ELECTRIC CORP

AI summary

A short-circuit detector detects an arm short circuit or a load short circuit, based on the magnitude of the gate current and the magnitude of the gate charge amount. The short-circuit detector includes: a gate current determinator that compares the magnitude of the gate current with at least one reference value; a gate charge amount determinator that compares the magnitude of the gate charge amount with at least one reference value; and a short-circuit detection logical operation circuitry that executes a logical operation of an output signal of the gate current determinator and an output signal of the gate charge amount determinator.