Switch-Mode Converter Rectifier Layout for EMC Noise Cancellation

Solution Overview

Problem

Automotive power systems face challenges with electromagnetic noise propagation, which can violate electromagnetic compatibility (EMC) standards and affect the performance of connected subsystems.

Innovation Solution

The implementation of switch mode power converters with specific transformer configurations and rectifying diode arrangements, where secondary coils are in phase with the primary coil and output circuits are designed to produce synchronized, out-of-phase noises, leading to partial cancellation of electromagnetic noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional rectifying diode arrangements are used in switch mode power converters, then the circuit structure is simple, but electromagnetic noise propagates and violates EMC standards

Engineering Contradiction:

Improveelectromagnetic noiseVSAvoidrectifying diode arrangement

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by connecting rectifying diodes to different terminals (dotted vs non-dotted) of secondary coils in a non-uniform manner. Specifically, one output circuit connects the anode to a dotted terminal while the other connects the cathode to a dotted terminal, creating asymmetric current paths that generate out-of-phase electromagnetic noise signals for cancellation purposes.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent converts the harmful electromagnetic noise generated by rectifying diodes into a beneficial cancellation effect. By strategically arranging the diodes and their connections to transformer secondary coils, the noise signals from different diodes are made out-of-phase, allowing them to cancel each other out and reduce overall electromagnetic interference in the circuit.

Inventive Principle:

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

2Reliability

If rectifying diodes are arranged to cancel electromagnetic noise, then EMC standards are met, but the circuit configuration becomes more complex

Engineering Contradiction:

Improveelectromagnetic compatibilityVSAvoidoutput circuit arrangement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by connecting rectifying diodes to different terminals (dotted vs non-dotted) of secondary coils in a non-uniform manner. Specifically, one output circuit connects the anode to a dotted terminal while the other connects the cathode to a dotted terminal, creating asymmetric current paths that generate out-of-phase electromagnetic noise signals for cancellation purposes.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent segments the power conversion function into multiple independent output circuits, each with its own rectifying diode and secondary coil connection. This segmentation allows each circuit to generate controlled electromagnetic noise that can be independently adjusted to achieve cancellation when combined with other segmented circuits, improving overall EMC through modular noise management.

Inventive Principle:

Principle #1Segmentation

3Use of energy by moving object

If secondary coils are connected in phase with the primary coil, then power transfer efficiency is improved, but electromagnetic noise propagation increases

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidelectromagnetic noise

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent applies asymmetry by connecting rectifying diodes to different terminals (dotted vs non-dotted) of secondary coils in a non-uniform manner. Specifically, one output circuit connects the anode to a dotted terminal while the other connects the cathode to a dotted terminal, creating asymmetric current paths that generate out-of-phase electromagnetic noise signals for cancellation purposes.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent converts the harmful electromagnetic noise generated by rectifying diodes into a beneficial cancellation effect. By strategically arranging the diodes and their connections to transformer secondary coils, the noise signals from different diodes are made out-of-phase, allowing them to cancel each other out and reduce overall electromagnetic interference in the circuit.

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

This design effectively reduces electromagnetic noise at sensitive points within the circuit, thereby improving electromagnetic compatibility and ensuring that vehicles meet EMC standards.

Implementation Method 1

rectifying diodes arranged such that electromagnetic noise generated by the rectifying diodes at least partially cancels

Methodology Applied

Scientific EffectElectromagnetic noise cancellation: Interference

Data Source

PatentUS20250202348A1Automotive power systems with noise mitigation

Publication Date: 2025.06.19 FORD GLOBAL TECH LLC

AI summary

A switch mode power converter, in one example, includes a transformer with a primary coil and a pair of secondary coils in phase with the primary coil, and a pair of output circuits defining a pair of opposite polarity outputs. Each of the output circuits includes a rectifying diode having an anode directly connected with a dotted terminal of one of the secondary coils such that electromagnetic noise generated by the rectifying diodes at least partially cancels.