Gate drive apparatus control method

Solution Overview

Problem

The existing gate drive circuits for inverters face a design contradiction between reducing leakage current and improving rise time of the gate drive signal, as a large resistance value is needed to reduce leakage current but a small resistance value is required for faster rise time.

Innovation Solution

A variable-resistive gate drive path is introduced between the bootstrap capacitor and the high-side switch, with different resistance values (R1 and R2) depending on the logic signal, utilizing a depletion mode transistor and a controllable switch to manage leakage current and rise time effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a large resistance value is used between the bootstrap capacitor and the gate of the high-side switch, then the leakage current is reduced, but the rise time of the gate drive signal increases

Engineering Contradiction:

Improveleakage currentVSAvoidrise time of gate drive signal

Core Design Contradiction:

Loss of energyVSSpeed

Solution Approach 1:

The patent applies the dynamics principle by making the resistance value variable rather than fixed. A control switch is introduced that dynamically changes the resistance between the bootstrap capacitor and the gate of the high-side switch based on the state of the low-side switch. When the low-side switch is off, the control switch connects a larger resistance to reduce leakage current. When the low-side switch is on, the control switch connects a smaller resistance to improve rise time. This dynamic adjustment resolves the contradiction between reducing leakage current and improving rise time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies the parameter changes principle by changing the resistance parameter based on operating conditions. The system transitions between two resistance states: a first resistance value when the low-side switch is off (to minimize leakage), and a second resistance value when the low-side switch is on (to maximize rise time performance). This parameter change is controlled by the state of the low-side switch, allowing optimal performance in both operating modes.

Inventive Principle:

Principle #35Parameter changes

2Speed

If a small resistance value is used between the bootstrap capacitor and the gate of the high-side switch, then the rise time of the gate drive signal is improved, but the leakage current increases

Engineering Contradiction:

Improverise time of gate drive signalVSAvoidleakage current

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent applies the dynamics principle by making the resistance value variable rather than fixed. A control switch is introduced that dynamically changes the resistance between the bootstrap capacitor and the gate of the high-side switch based on the state of the low-side switch. When the low-side switch is off, the control switch connects a larger resistance to reduce leakage current. When the low-side switch is on, the control switch connects a smaller resistance to improve rise time. This dynamic adjustment resolves the contradiction between reducing leakage current and improving rise time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies the parameter changes principle by changing the resistance parameter based on operating conditions. The system transitions between two resistance states: a first resistance value when the low-side switch is off (to minimize leakage), and a second resistance value when the low-side switch is on (to maximize rise time performance). This parameter change is controlled by the state of the low-side switch, allowing optimal performance in both operating modes.

Inventive Principle:

Principle #35Parameter changes

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 reduces leakage current while improving the rise time of the gate signal, enhancing the switching performance of the inverter without the need for large resistive devices, thus improving efficiency and reliability.

Implementation Method 1

The leakage current is self-limited by pinching off the current through the depletion mode transistor through self-biasing

Methodology Applied

Scientific EffectSelf-biasing:

Implementation Method 2

The leakage current is self-limited by pinching off the current through the depletion mode transistor through self-biasing

Methodology Applied

Scientific EffectPinch-off effect:

Implementation Method 3

A high-side drive circuit and a low-side drive circuit are employed to control the gates of the high-side switch and the low-side switch respectively. In order to turn on the high-side switch, the high-side drive circuit may need a gate voltage higher than the voltage of the power source. This may be accomplished with a bootstrap capacitor circuit.

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11876511B2Gate drive apparatus control method

Publication Date: 2024.01.16 DIODES INC

AI summary

An apparatus includes a capacitive device configured to provide bias power for a high-side switch, a gate drive path having variable resistance connected between the capacitive device and a gate of the high-side switch, wherein the gate drive path having variable resistance is of a first resistance value in response to a turn-on of the high-side switch, and the gate drive path having variable resistance is of a second resistance value in response to a turn-off of the high-side switch, and wherein the second resistance value is greater than the first resistance value, and a control switch connected between the gate of the high-side switch and ground.