Half-Bridge Gate Driver Blanking Time Control for Switch Protection

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Solution Overview

Problem

Existing gate drivers face challenges in accurately setting a blanking time to prevent erroneous triggering of protection functions, which can lead to damage, and require complex circuitry and significant circuit area, especially when driving high-voltage phases in three-phase inverters.

Innovation Solution

A gate driver system that generates an internal pulsed high side control signal based on a high side control signal and a timing control signal, enabling and activating a high side support function circuit to define the blanking time, allowing for efficient and safe operation of high side switches, and similarly controls low side switches with a low side support function circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the blank time is set too long to prevent erroneous triggering of protection functions, then the reliability of protection is improved, but the risk of belated triggering increases which may damage the power switch

Engineering Contradiction:

Improveprotection function reliabilityVSAvoidblanking time delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent implements dynamic blanking time adjustment by using a ramp-up signal that varies over time. The comparator detects when the ramp-up signal exceeds a reference value to dynamically determine the end of the blanking period, allowing the blanking time to adapt to different operating conditions rather than being fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the temporal parameter of blanking time by introducing a time-varying ramp-up signal. The blanking period is defined by the time it takes for the ramp-up signal to reach a threshold, effectively transforming the blanking time from a static value to a dynamically controllable parameter that can be adjusted based on circuit conditions.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If passive components are used to fix the blank time during design stage, then the blanking time stability is improved, but the circuit area increases significantly

Engineering Contradiction:

Improveblanking time stabilityVSAvoidcircuit area

Core Design Contradiction:

Stability of the object's compositionVSArea of stationary object

Solution Approach 1:

The patent extracts the timing function from passive RC components and implements it using an active ramp-up signal generated by the control circuit. This removes the need for large physical capacitors and resistors, significantly reducing the circuit area while maintaining stable and adjustable blanking time.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/passive RC timing system with an electronic control system that generates ramp-up signals. This substitution allows for more compact implementation while providing better control over the blanking time parameter through electronic signal manipulation rather than physical component dimensions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If high-voltage isolation is implemented between passive components for three-phase inverters, then the safety is improved, but the circuit complexity and area increase

Engineering Contradiction:

Improvehigh-voltage isolation safetyVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a universal ramp-up signal generation mechanism that can be shared across multiple phases. The control circuit generates timing signals that can control multiple power switches, reducing the need for separate isolation circuits for each phase and thereby simplifying the overall system while maintaining safety.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Manufacturing precision

If the blank time is fixed by passive component dimensions, then the manufacturing precision is improved, but the adaptability to different scenarios decreases

Engineering Contradiction:

Improveblanking time precisionVSAvoidblanking time adaptability

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent makes the blanking time dynamic by using a controllable ramp-up signal whose characteristics can be adjusted. This allows the same circuit to adapt to different scenarios and operating conditions while maintaining precise control over the blanking period through electronic parameters rather than fixed physical dimensions.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20240421692A1Gate driver and method for driving a power switch with blanking time control

Publication Date: 2024.12.19 INFINEON TECH AUSTRIA AG

AI summary

A gate driver for driving a half-bridge is disclosed, which includes a low voltage control logic, a high side switch control circuit and a low side switch control circuit. The low voltage control circuit generates an internal pulsed high side control signal based on a high side control signal and a common protection function blanking control signal and a low side protection function activation signal based on a low side control signal and the common protection function blanking control signal. The high side switch control circuit includes a high side protection function circuit, which is enabled based on a first pulse of the internal pulsed high side control signal and is activated based on a second pulse of the internal high side pulsed control signal. The low side switch control includes a low side protection function circuit, which is activated based on the protection function activation signal.