Parallel Switching Arms Inductor Current Imbalance

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Solution Overview

Problem

High-power voltage converters with parallel switching arms experience current imbalances due to differing electrical characteristics and thermal conditions, leading to potential switch destruction during switching phases.

Innovation Solution

Incorporating an inductor with a value greater than 10 nH between the conduction electrodes and common conduction terminals of each parallel arm, ensuring identical inductance across all arms, along with capacitors and resistors to manage current and voltage imbalances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If two electronic switches are connected in parallel to allow higher current circulation, then the current handling capability is improved, but current imbalance between switches occurs during switching phases leading to potential destruction

Engineering Contradiction:
Improvecurrent handling capabilityVSAvoidswitch reliability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent introduces inductors with specific inductance values (greater than 10 nH) in series with each parallel switching arm to modify the electrical parameters of the circuit. This parameter change equalizes the current distribution during switching transitions by compensating for differences in switch characteristics, thereby resolving the current imbalance problem while maintaining high current handling capability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The inductor acts as an intermediary element between the parallel switches and the common conduction terminal. It mediates the current flow during switching transitions, preventing direct current imbalance between switches by introducing a reactive element that smooths current distribution and protects the switches from destructive current spikes

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If switches with different electrical characteristics are used in parallel arms, then device flexibility is improved, but current distribution uniformity deteriorates

Engineering Contradiction:
Improvedevice flexibilityVSAvoidcurrent distribution uniformity
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

By introducing inductors with carefully selected inductance values into each parallel arm, the patent changes the overall impedance characteristics of each branch. This parameter modification compensates for differences in switch characteristics, ensuring that current distributes uniformly across parallel arms even when switches have different electrical characteristics, thus maintaining both flexibility and uniformity

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If inductors with inductance greater than 10 nH are added to each parallel arm, then current balance is improved, but device complexity increases

Engineering Contradiction:
Improvecurrent balanceVSAvoidcircuit complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent achieves current balance by modifying the inductance parameter of each parallel arm to be greater than 10 nH. This specific parameter range provides sufficient current equalization while minimizing the physical size and complexity of the inductor components, thus improving current balance without excessive increase in device complexity

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

The solution effectively reduces current imbalances between parallel switching arms, maintaining consistent voltage and current delivery while extending switch lifespan by equalizing switching properties across all arms.

Implementation Method 1

each of the arms connected in parallel, an inductor connected between the same electrode among the two conduction electrodes and the corresponding common conduction terminal, the inductance having a value greater than 10 nH

Methodology Applied
Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentEP2751916B1High-power converter including low-power transistors connected in parallel
Publication Date: 2020.05.13 GE ENERGY POWER CONVERSION TECHNOLOGY LTD(GB)
  • EP2751916B1 patent drawingFigure 1~2
  • EP2751916B1 patent drawingFigure 3~4
  • EP2751916B1 patent drawing

AI summary

The invention relates to a system for converting a first electric voltage into a second electric voltage, comprising: at least two input terminals and two output terminals; and switching members (16) disposed between the input and output terminals, which can convert the first voltage into the second voltage. At least one switching member (16) comprises at least two arms (26) connected in parallel and each arm includes an electronic switch (34) that can be controlled such as to occupy either an on-state or an off-state, said switch comprising a control electrode (36) and two conduction electrodes (38, 40) that conduct current in the on-state. The switching member (16) comprises a common control terminal (28) connected to the control electrode (36) of the switch of each arm, as well as a first common conduction terminal (30) and a second common conduction terminal (32) connected respectively to a first conduction electrode (38) and a second conduction electrode (40) of the switch (34) of each of the arms. The switching member (16) also comprises, for each arm, an inductance (42) connected between the same single electrode from the two conduction electrodes (38, 40) and the corresponding common conduction terminal (30, 32), and the inductance (42) is greater than 10 nH and substantially identical for each arm.