Gate Drive Overcurrent Detection With Clamp Diode Noise Suppression
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Solution Overview
Problem
Conventional semiconductor drive devices face challenges in accurately detecting overcurrent in semiconductor switching elements due to noise interference, leading to potential erroneous operations during ON/OFF cycles.
Innovation Solution
The semiconductor drive device incorporates an overcurrent protection unit with an overcurrent determination unit that utilizes a clamp diode, a first transistor, and a low-pass filter to accurately detect overcurrent without requiring a power supply, while a gate voltage reducing unit reduces the gate voltage to protect the semiconductor switching element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If overcurrent is detected using threshold voltage of transistor without power supply, then power consumption is reduced and device simplicity is improved, but noise resistance deteriorates causing erroneous detection during ON/OFF operation
Solution Approach 1:
A clamp diode is introduced as an intermediary component between the detection signal input and the transistor base. The clamp diode clamps the potential at the signal input part to the control terminal potential, preventing noise-induced potential fluctuations from reaching the transistor while allowing legitimate overcurrent detection signals to pass through.
Solution Approach 2:
The clamp diode performs preliminary potential stabilization at the signal input part before the detection signal reaches the transistor. By pre-clamping the potential to the control terminal potential, the system prevents noise from causing erroneous transistor activation during the critical ON/OFF transition periods.
2Adaptability or versatility
If semiconductor switching element and gate drive unit are separated by long wiring, then device layout flexibility is improved, but overcurrent detection accuracy deteriorates due to wiring inductance and noise
Solution Approach 1:
The clamp diode acts as a local intermediary at the overcurrent protection unit, compensating for the degraded signal quality that results from long wiring separation. It ensures that even when the detection signal travels through noisy long wiring, the potential at the critical input point remains clamped to the control terminal potential, maintaining detection accuracy.
Solution Approach 2:
The invention applies local potential clamping at the signal input part of the overcurrent protection unit, creating a localized noise-immune zone. This local quality enhancement ensures that the critical comparison operation occurs with a stable reference potential, regardless of the quality of the incoming detection signal from distant wiring.
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 enables reliable overcurrent protection for semiconductor switching elements, preventing erroneous operations due to noise and ensuring high reliability even when the semiconductor switching element and the gate drive unit are separated by long wiring.
Implementation Method 1
an overcurrent determination unit which receives a detection signal based on voltage/current between main terminals of the semiconductor switching element and determines whether there is overcurrent flowing through the semiconductor switching element
Implementation Method 2
a low-pass filter provided at the signal input part
Data Source
AI summary
A semiconductor drive device includes a gate drive unit which drives a semiconductor switching element, and an overcurrent protection unit. The overcurrent protection unit includes an overcurrent determination unit which receives a detection signal and determines whether there is overcurrent, and a gate voltage reducing unit which reduces gate-applied voltage when it is determined that there is the overcurrent. The overcurrent determination unit includes a clamp diode for clamping a potential of an input part for the detection signal at a gate potential, a first transistor to which the input part is connected, and a low-pass filter. When the potential of the input part has reached a set value, the first transistor is turned on so that it is determined that there is the overcurrent in the semiconductor switching element.