RLC Branches Mitigate Voltage Spikes in Power Converters

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Solution Overview

Problem

Conventional non-isolated full bridge power converters, such as dual buck converters, experience undesirable voltage spikes due to common mode perturbations like jitter in switching, which stress electrical insulation and reduce converter lifetime.

Innovation Solution

Incorporating auxiliary RLC branches with selected resistive, inductive, and capacitive components that produce natural periods longer than the duration of switching transients, mitigating voltage spikes during commutation by acting as low pass filters and providing a path for voltage stabilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional non-isolated full bridge power converters are used, then the converter structure is simple and component cost is low, but voltage spikes occur during switching commutation which stress electrical insulation and reduce converter lifetime

Engineering Contradiction:

Improveconverter lifetimeVSAvoidvoltage spikes

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces RLC auxiliary branches as intermediary elements connected between input and output terminals. These branches act as mediators that provide alternative current paths during switching commutation, thereby mitigating voltage spikes without fundamentally changing the main power conversion topology. The RLC components absorb and dissipate the harmful voltage transients.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The RLC auxiliary branches are pre-configured with specific resistance, inductance, and capacitance values designed to counteract voltage spikes before they can cause damage. The natural period of these branches is intentionally set longer than the switching transient duration, creating a cushioning effect that protects the converter during commutation events.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If RLC auxiliary branches are added to mitigate voltage spikes, then converter reliability and stability are enhanced, but device complexity and component cost increase

Engineering Contradiction:

Improveconverter stabilityVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Rather than completely redesigning the power converter topology, the patent applies a partial solution by adding only the necessary RLC auxiliary branches. This approach provides sufficient voltage spike mitigation without implementing excessive complexity. The branches are added selectively to address the specific problem of commutation spikes while maintaining the simplicity of the main power conversion path.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent optimizes the parameters (R, L, C values) of the auxiliary branches to achieve effective voltage spike mitigation with minimal component values. By carefully selecting parameters where the natural period exceeds the switching transient duration, the solution achieves reliability improvement without requiring large or numerous components that would increase complexity.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If switching frequency is increased to improve productivity, then power conversion efficiency improves, but voltage spikes become more severe and jitter tolerance decreases

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidvoltage spike severity

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of high-frequency switching by using the RLC auxiliary branches to harness the switching transients. The branches are designed to resonate at frequencies that transform the harmful high-frequency voltage spikes into beneficial controlled energy dissipation, allowing high switching frequencies to be used without exacerbating voltage stress.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 mitigates voltage spikes, enhancing the stability and longevity of the power converter by allowing wider time windows for switching and tolerance for jitter, while maintaining simplicity and low component costs.

Implementation Method 1

Methodology Applied

Scientific EffectLow pass filter: Filter (electronic)

Data Source

PatentUS9235227B2Apparatus and method for mitigating perturbations in a power converter

Publication Date: 2016.01.12 GENERAL ELECTRIC CO

AI summary

A power converter includes a plurality of switches that interconnect first and second input terminals of the power converter with first and second output terminals of the power converter. The switches are switched to convert power from the input terminals to the output terminals. During the switching, voltage spikes are mitigated by a first RLC branch connected from the first input terminal to the first output terminal and by a second RLC branch connected from the second input terminal to the second output terminal.