Parallel Half-Bridge Converter Control for Common-Mode Noise

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing power converters face challenges with high switching losses and common mode noise due to bulky filter components, unpredictable common mode current spikes, and saturation issues, especially when external CM noise is present, making it difficult to design effective passive filters.

Innovation Solution

A power converter with a control circuit that uses a modified reference voltage signal, incorporating current feedback, to manage switching times of semiconductor switches, reducing common mode noise through active compensation and minimizing passive filter size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If passive filter components are increased in size to handle high common mode noise, then common mode noise is reduced, but the filter becomes bulkier and heavier

Engineering Contradiction:

Improvecommon mode noiseVSAvoidfilter weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

The patent implements active common mode current compensation by measuring the common mode current with sensors and injecting a compensating current through additional switching devices. This feedback-based active compensation reduces common mode noise without requiring oversized passive filter components, thereby avoiding the weight penalty associated with larger capacitors and inductors.

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If passive filter components are increased in size to handle high common mode noise, then common mode noise is reduced, but the filter complexity and cooling requirements increase

Engineering Contradiction:

Improvecommon mode noiseVSAvoidfilter complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent uses active feedback compensation where common mode current is measured and a compensating signal is generated and injected. This approach replaces complex passive filtering with a controlled active system that uses switching devices and control circuitry to achieve noise reduction without oversizing components.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical/passive filtering approach (large inductors and capacitors) with an electronic control approach using switching devices and control circuits. This substitution eliminates the need for bulky passive components and their associated cooling requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of energy

If discontinuous PWM is used to reduce switching losses, then switching losses are reduced, but common mode current spikes increase

Engineering Contradiction:

Improveswitching lossesVSAvoidcommon mode current spikes

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The patent measures common mode current using sensors and uses this information in a feedback control loop to generate a compensating current. This active compensation counteracts the common mode current spikes generated by discontinuous PWM, allowing the system to maintain the low switching losses of DPWM while eliminating the harmful current spikes.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent takes the common mode current spikes, which are harmful side effects of discontinuous PWM, and converts them into a controllable parameter by measuring and actively compensating for them. The compensation current transforms the harmful spikes into a controlled phenomenon that can be eliminated while preserving the benefits of DPWM.

Inventive Principle:

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

4Object-affected harmful factors

If filter components are oversized to handle unpredictable common mode current spikes, then common mode noise is reduced, but component size and cost increase

Engineering Contradiction:

Improvecommon mode noiseVSAvoidfilter volume

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

The patent implements real-time measurement and active compensation of common mode current, allowing the system to handle unpredictable current spikes dynamically rather than requiring static oversizing of passive components. This feedback approach enables compact filter design while maintaining effective noise suppression.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12542477B2Power converter

Publication Date: 2026.02.03 SIEMENS AG

AI summary

Various embodiments of the teachings herein include a power converter to convert between a first, AC voltage and a second voltage. An example includes: half-bridges connected in parallel, each comprising two semiconductor switches connected serially with outer terminals of the half-bridge forming terminals for the second voltage; a filter connected between midpoints of the half-bridges and terminals for the first voltage, comprising an inductor and a capacitor; a sensor for each half-bridge to measure current flowing between the midpoints of the half-bridges and the filter circuit; and a control circuit to operate the switches. The control circuit determines switching times using a modified reference voltage signal resulting in a softened bus clamp modulation. A controller creates the modified reference voltage signal using an unmodified reference voltage signal as a setpoint input and a sum of the current signals from the current sensors as measured input.