Temperature-Compensated Gate Driver for Parallel IGBT Current Balancing

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Solution Overview

Problem

In electrified vehicles, solid state switches like IGBTs face challenges in maintaining balanced operation across varying temperatures, leading to unbalanced current flow and increased energy losses due to differences in threshold voltages and temperature coefficients, which can result in overheating and reduced operational lifetime.

Innovation Solution

A self-balancing temperature-compensated gate driver adjusts the gate current based on temperature feedback from diode arrays, ensuring balanced current flow during both turn-on and turn-off transients by compensating for temperature differences between parallel-connected switches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If solid state switches are operated at high voltage and high current to improve power output, then power delivery capability is improved, but thermal management difficulty and energy losses increase

Engineering Contradiction:

Improvepower delivery capabilityVSAvoidenergy losses

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent implements a feedback mechanism where temperature sensors continuously monitor the junction temperature of each IGBT switch and feed this information back to the control system. The controller adjusts the gate driving signals in real-time based on temperature feedback, reducing the switching duty cycle of overheating switches and redistributing current to cooler switches, thereby preventing thermal runaway and reducing energy losses.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes operating parameters (gate driving voltage, switching frequency, duty cycle) based on real-time temperature conditions. When IGBT temperature exceeds predetermined thresholds, the controller modifies these parameters to reduce power dissipation and thermal stress, enabling safe operation at high voltage and current while managing thermal effects.

Inventive Principle:

Principle #35Parameter changes

2Power

If multiple IGBT switches are connected in parallel to increase current capacity, then current handling capability is improved, but current balance difficulty increases

Engineering Contradiction:

Improvecurrent handling capabilityVSAvoidcurrent balance precision

Core Design Contradiction:

PowerVSManufacturing precision

Solution Approach 1:

The patent employs individual temperature sensors for each parallel-connected IGBT switch, creating independent feedback loops for each device. The controller continuously monitors temperature differences between parallel switches and dynamically adjusts gate driving signals to equalize current distribution, compensating for manufacturing variations and ensuring balanced operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies localized control strategies to each individual IGBT switch in the parallel configuration. Each switch receives customized gate driving signals tailored to its specific temperature and current conditions, rather than uniform control, enabling precise current balancing despite manufacturing tolerances and thermal gradients.

Inventive Principle:

Principle #3Local quality

3Productivity

If high switching frequency is used to improve power conversion efficiency, then power conversion efficiency is improved, but switching losses and thermal stress increase

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidswitching losses

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent dynamically adjusts switching frequency and duty cycle based on real-time temperature feedback. When IGBT temperature approaches critical thresholds, the controller reduces switching frequency and modifies duty cycle to minimize switching losses and thermal stress, while maintaining adequate power conversion efficiency through adaptive control.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements periodic temperature monitoring and adaptive switching control. The system continuously cycles through measurement-evaluation-adjustment phases, periodically modifying switching parameters based on accumulated thermal data, enabling sustained high-frequency operation with thermal management.

Inventive Principle:

Principle #19Periodic action

4Power

If high voltage operation is used to reduce current requirements, then power density is improved, but voltage stress and insulation requirements increase

Engineering Contradiction:

Improvepower densityVSAvoidvoltage stress resistance

Core Design Contradiction:

PowerVSStrength

Solution Approach 1:

The patent incorporates temperature-dependent protective control that anticipates thermal runaway before it occurs. By monitoring temperature trends and preemptively reducing duty cycle or shutting down switches approaching critical temperatures, the system cushions against voltage stress and insulation breakdown that would result from uncontrolled thermal escalation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS10090792B2Self-balancing parallel power devices with a temperature compensated gate driver

Publication Date: 2018.10.02 FORD GLOBAL TECH LLC

AI summary

A powertrain includes a first and second switch coupled in parallel to drive an electric machine and a gate driver. The gate driver may be configured to, in response to a transition request while a first temperature of the first switch exceeds a second temperature of the second switch, inject a current onto a gate of the second switch to drive rates of change of current through the first and second switch to the electric machine to a same value.