Variable-Current Gate Driver for Fast IGBT Switching

Solution Overview

Problem

Existing gate drive circuits for power switching elements, such as IGBTs, face challenges in reducing current consumption while maintaining high-speed switching, as they often require continuous high current levels even after the switching element is turned on, leading to increased power consumption and potential damage from overshoot.

Innovation Solution

A load driver with a constant current generator that supplies a higher current value to turn on the switching element quickly and then reduces the current value once the element is on, using a variable constant current circuit to minimize current consumption after the switching element reaches the on state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a higher constant current value is supplied to turn on the switching element quickly, then the rising time is shortened and switching speed increases, but the current consumption in the driver circuit increases

Engineering Contradiction:

Improveswitching speedVSAvoidcurrent consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the constant current value variable rather than fixed. The constant current generator switches between a first current value (higher) during the rising time period and a second current value (lower) afterward, allowing the system to adapt current consumption to the actual switching state and minimize energy usage while maintaining high switching speed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses periodic action by dividing the current supply into distinct time periods: a first period during the rising time when higher current is supplied to charge the gate capacitance quickly, and a second period afterward when lower current is supplied to maintain the on-state, thereby achieving fast switching with reduced continuous current consumption

Inventive Principle:

Principle #19Periodic action

2Reliability

If a clamp circuit is connected to restrict gate voltage overshoot, then the switching element is protected from damage, but a current path is formed and current consumption increases

Engineering Contradiction:

Improveprotection from overshootVSAvoidcurrent consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the constant current value variable rather than fixed. The constant current generator switches between a first current value (higher) during the rising time period and a second current value (lower) afterward, allowing the system to adapt current consumption to the actual switching state and minimize energy usage while maintaining high switching speed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses periodic action by dividing the current supply into distinct time periods: a first period during the rising time when higher current is supplied to charge the gate capacitance quickly, and a second period afterward when lower current is supplied to maintain the on-state, thereby achieving fast switching with reduced continuous current consumption

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS8633755B2Load driver with constant current variable structure

Publication Date: 2014.01.21 DENSO CORP

AI summary

A load driver includes a switching element connected to a load, a constant current generator that generates a constant current, and a driver circuit that turns on the switching element for an on-period, which depends on a value of the constant current and is shortened with an increase in the value of the constant current. The constant current generator supplies a first constant current having a first current value to the driver circuit during the on-period, and supplies a second constant current having a second current value smaller than the first current value after the on-period has elapsed and the switching element reaches an on state.