Gate Driver Boost Interval Control for SiC Turn-On Oscillation

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Solution Overview

Problem

Power transistors, especially silicon carbide (SiC) transistors, face challenges in optimizing switching processes due to wide operating ranges, leading to oscillation and energy losses, with simple control methods failing to set optimal switching speed limits and oscillation prevention across varying operating points.

Innovation Solution

A gate driver system with a multistage gate driver circuit and measurement circuit that adjusts the boost interval based on measured transistor parameters, such as oscillation of the drain current, to regulate the switching speed and prevent oscillation, optimizing the switching process for each operating point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a fast turn-on process is used, then switching losses are reduced, but oscillation and electromagnetic interference increase

Engineering Contradiction:

Improveswitching lossesVSAvoidoscillation and electromagnetic interference

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The gate driver dynamically adjusts the gate current amplitude and/or duration based on real-time operating conditions (voltage, current, temperature) to optimize switching speed. This dynamic adaptation allows the system to achieve fast switching when conditions permit while preventing oscillation when conditions require more conservative switching, thereby resolving the contradiction between reducing switching losses and preventing electromagnetic interference

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes key parameters (gate current amplitude, gate voltage, switching duration) based on measured operating conditions. By monitoring voltage, current, and temperature, the gate driver modifies these parameters in real-time to achieve optimal switching performance that minimizes both switching losses and harmful oscillations across different operating points

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a simple control method is used, then device complexity is reduced, but optimal switching speed limit cannot be set across wide operating range

Engineering Contradiction:

Improvecontrol circuit complexityVSAvoidswitching speed optimization across operating points

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The gate driver incorporates feedback mechanisms that monitor operating conditions (voltage, current, temperature) and use this information to automatically adjust switching parameters. This feedback loop enables the simple control circuit to adapt to wide operating ranges and set optimal switching speed limits dynamically, achieving high adaptability without increasing device complexity

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system performs self-adjustment by monitoring its own operating conditions and automatically modifying its behavior. The gate driver assesses the current operating point and independently determines the optimal switching parameters, eliminating the need for complex external control circuits while maintaining adaptability across wide operating ranges

Inventive Principle:

Principle #25Self-service

3Productivity

If switching speed is increased, then productivity is improved, but electrical overload risk increases

Engineering Contradiction:

Improveswitching frequencyVSAvoidelectrical overload prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Before executing a switching operation, the gate driver pre-assesses the operating conditions (voltage, current, temperature) to determine whether the transistor can safely handle the intended switching speed. This preliminary evaluation prevents electrical overload by identifying unsafe conditions before they cause damage, while still allowing high switching frequencies when conditions are favorable

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11444613B1Actively tracking switching speed control and regulating switching speed of a power transistor during turn-on

Publication Date: 2022.09.13 INFINEON TECHNOLOGIES AG

AI summary

A gate driver system includes a gate driver circuit coupled to a gate terminal of a transistor and configured to generate an on-current during a plurality of turn-on switching events to turn on the transistor, wherein the gate driver circuit includes a first driver configured to source a first portion of the on-current to the gate terminal to charge a first portion of the gate voltage and a second driver configured to, during a first boost interval, source a second portion of the on-current to the gate terminal to charge a second portion of the gate voltage; a measurement circuit configured to measure a transistor parameter indicative of an oscillation of a load current for a turn-on switching event; and a controller configured to receive the measured transistor parameter and regulate a length of the first boost interval based on the measured transistor parameter.