Commutation Cell With Dynamic Compensation Circuit

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional power electronic switches experience overvoltage issues during turn-off, leading to reduced efficiency and potential premature failure, as existing solutions either slow down switching times or require overdesigning commutation cells to manage varying bus voltages, limiting their maximum power output.

Innovation Solution

A dynamically controlled compensation circuit is connected to the parasitic emitter inductance of the power electronic switch, using a controllable voltage divider to inject a portion of the overvoltage into the gate driver, thereby reducing the voltage across the high frequency loop and optimizing overvoltage management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the turn-off speed of the power electronic switch is accelerated to reduce switching losses, then switching efficiency is improved, but overvoltage is generated in parasitic inductances

Engineering Contradiction:

Improveswitching lossesVSAvoidovervoltage

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

A compensation circuit is introduced as an intermediary between the power electronic switch and the gate driver. This circuit includes a compensation capacitor connected in parallel with the parasitic emitter inductance, which mediates the overvoltage by providing an alternative current path during switching transitions, thereby reducing the voltage spike while allowing fast switching

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention dynamically adjusts the compensation capacitor value based on operating conditions (bus voltage, switching frequency, load current). By changing the capacitance parameter adaptively, the system optimizes the trade-off between switching speed and overvoltage suppression, allowing fast switching at high bus voltages while preventing excessive overvoltage at lower voltages

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the turn-off speed is slowed down to protect against overvoltage, then overvoltage is reduced, but switching losses increase and efficiency decreases

Engineering Contradiction:

ImproveovervoltageVSAvoidswitching losses

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The compensation capacitor acts as a mediator that absorbs the overvoltage energy during turn-off, eliminating the need to slow down the switching speed. This allows the switch to turn off rapidly while the capacitor handles the voltage transient, preventing both overvoltage and switching losses from occurring simultaneously

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If commutation cells are overdesigned to manage varying bus voltages, then overvoltage protection is improved, but maximum power output is limited

Engineering Contradiction:

Improveovervoltage protectionVSAvoidmaximum power output

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The compensation capacitor value is made dynamically adjustable rather than fixed, allowing the system to adapt to varying bus voltages and operating conditions. This dynamic adjustment enables the system to operate at maximum power output across different voltage levels while maintaining overvoltage protection, eliminating the need for conservative overdesign

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

By changing the compensation capacitor parameter based on real-time operating conditions, the system optimizes performance for each specific scenario. At high bus voltages, the capacitor is adjusted to provide maximum overvoltage suppression, while at lower voltages, the capacitance is reduced to minimize impact on power output, allowing the system to operate at maximum power across the full voltage range

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 approach effectively limits switching overvoltage, enhances efficiency, and allows commutation cells to operate at maximum power output even under varying bus voltages, extending the lifespan of power electronic switches.

Implementation Method 1

a parasitic emitter inductance through which a voltage is generated upon turning on and off of the power electronic switch

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The compensation circuit applies a controllable portion of the voltage generated through the parasitic emitter inductance at turn-off of the power electronic switch to control the voltage generated through the parasitic emitter inductance

Methodology Applied

Scientific EffectFeedback control: Feedback

Data Source

PatentUS9882465B2Commutation cell, power converter and compensation circuit having dynamically controlled voltage gains

Publication Date: 2018.01.30 DANA TM4 INC

AI summary

A commutation cell is configured for limiting switching overvoltage. The commutation cell includes a power electronic switch having a parasitic emitter inductance through which a voltage is generated upon turning off of the power electronic switch. The commutation cell also includes a dynamically controlled compensation circuit connected to the parasitic emitter inductance. The compensation circuit applies a controllable portion of the voltage generated through the parasitic emitter inductance at turn-off of the power electronic switch to control the voltage generated through the parasitic emitter inductance. A power converter includes a pair of commutation cells and a compensation circuit of the commutation cell.