Gate Voltage Overshoot Detection in Power Switch Overload Protection

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Solution Overview

Problem

Power switch circuits face challenges in efficiently detecting and responding to overload conditions, particularly in high-speed switching applications, where existing methods like desaturation protection and overcurrent protection have slow response times and may lead to false failures or inefficiencies.

Innovation Solution

The implementation of a voltage detection circuit that leverages electrostatic discharge (ESD) protection components to monitor voltage changes at the control terminal of power switches, allowing for fast detection of voltage overshoots and triggering protective measures such as shutting off the power switch when an overload condition is detected, thereby enhancing safety and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional desaturation protection or overcurrent protection methods are used, then the power switch circuit can detect overload conditions, but the response time is slow leading to inefficiency and potential false failures

Engineering Contradiction:

Improveoverload detection accuracyVSAvoidresponse time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The voltage detection circuit monitors the control terminal voltage continuously before overload damage occurs. By detecting voltage overshoot at the gate terminal as an early indicator of overload condition, the system triggers protective measures in advance, achieving fast response without waiting for traditional desaturation or overcurrent signals.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses the control terminal voltage as an intermediary signal to detect overload conditions. Instead of directly monitoring current or power switch state, the voltage at the control terminal serves as a mediator that indicates impending overload, enabling faster and more accurate detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the switching speed of power switches is increased to improve efficiency, then power delivery control is enhanced, but fast overload detection and response become more critical for safety

Engineering Contradiction:

Improveswitching speedVSAvoidoverload damage risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The voltage detection circuit provides continuous feedback on the control terminal voltage state. When voltage overshoot indicating overload is detected, the system immediately feeds back a shutdown signal to the power switch driver, stopping further power delivery. This closed-loop feedback ensures fast response to overload conditions in high-speed switching applications.

Inventive Principle:

Principle #23Feedback

3Loss of energy

If higher efficiency components are used to improve power delivery, then the risk of damage from high currents increases, requiring better protection mechanisms

Engineering Contradiction:

Improvepower efficiencyVSAvoidhigh current damage

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The voltage detection circuit acts as a protective cushion by detecting voltage overshoot before high current can cause damage to efficiency components. The early detection at the control terminal allows the system to shut down the power switch before destructive currents flow, protecting high-efficiency components from overload damage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 approach enables faster overload detection and response compared to traditional methods, allowing for the use of higher efficiency components and reducing the risk of damage from high currents, while improving safety and operational efficiency in power switch circuits.

Implementation Method 1

a voltage detection circuit, configured to detect a voltage overshoot on the control terminal of the power switch

Methodology Applied

Scientific EffectVoltage overshoot detection:

Implementation Method 2

the circuit arrangement of this disclosure may provide fast overload detection by leveraging electrostatic discharge (ESD) protection components to detect a voltage change at the control terminal of the power switch

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentUS11901883B2Diagnosis of gate voltage to detect high current

Publication Date: 2024.02.13 INFINEON TECHNOLOGIES AG

AI summary

Overload detection and protection for power switch circuits. For circuits with faster switching speed, fast fault detection and response to a detected overload condition may be desirable. Detection circuitry may monitor a voltage on the control terminal of one or more power switches. Based on empirical measurements, in an overload condition of a power switch circuit, e.g., a half-bridge circuit, the voltage at the control terminal may increase, and in some examples, increase to a magnitude that is greater than a supply voltage. A comparator may detect a voltage increase that exceeds a voltage magnitude threshold, output an indication to control circuitry for the power switch circuit, and the control circuitry may take action to protect the rest of the circuitry, such as reduce voltage or shut off the power switch circuit.