Integrated EMI Filter for Motor Controllers

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Solution Overview

Problem

Existing electric motors and switching power supplies generate significant conducted electromagnetic interference (EMI), which is difficult to manage due to size and cost constraints of traditional EMI filters, necessitating a solution that reduces EMI effectively while being compact and cost-efficient.

Innovation Solution

The implementation of a hybrid twin motor system with a compact EMI filter design, including a common motor drive circuit, low-capacitance and high-capacitance DC-links, and strategically placed choke devices and capacitors to suppress EMI noise, integrated within the motor drive circuit to meet FCC Class A and B standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If large, bulky EMI filters are connected to the motor controller to reduce EMI, then EMI reduction is achieved, but the device size increases and manual installation is required

Engineering Contradiction:

Improveconducted EMIVSAvoidEMI filter size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The EMI filter is integrated directly into the motor controller housing, merging two previously separate components (EMI filter and motor controller) into a single unified device. This eliminates the need for separate bulky EMI filters while maintaining EMI reduction functionality, thereby reducing overall device volume and eliminating manual installation of separate filters.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The motor controller housing is designed to serve multiple functions: it houses the control electronics and simultaneously functions as the EMI filter enclosure. This multi-functional design allows the same structure to provide both control and EMI filtering capabilities, reducing the need for additional dedicated EMI filter components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If large, bulky EMI filters are connected to the motor controller to reduce EMI, then EMI reduction is achieved, but manual installation is required which increases installation complexity

Engineering Contradiction:

Improveconducted EMIVSAvoidinstallation ease

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

By integrating the EMI filter into the motor controller housing, the system reduces the number of separate components that need to be installed and connected. The unified design allows for simpler installation as a single pre-assembled unit rather than requiring manual connection of separate EMI filter components to the motor controller.

Inventive Principle:

Principle #5Merging (Combining)

3Object-affected harmful factors

If traditional EMI filter designs are used, then EMI reduction is achieved, but the filter takes up significant space and increases system cost

Engineering Contradiction:

Improveconducted EMIVSAvoidsystem complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The integration of the EMI filter into the motor controller housing consolidates components and reduces system complexity. By combining what were previously separate EMI filter and motor controller units, the system requires fewer connection points, less wiring, and simpler assembly procedures.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The motor controller housing is designed to serve multiple functions simultaneously - housing control electronics and providing EMI filtering capability. This multi-functional approach eliminates the need for dedicated EMI filter components, thereby reducing overall system complexity and component count.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 EMI noise to meet regulatory standards, achieving higher power density and lower system costs while eliminating the need for bulky manual installations, thereby enhancing the performance and efficiency of electric motors.

Implementation Method 1

a first choke device coupled across the first and second conductive paths

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

a first Y capacitor including a first end and a second end opposite the first end, the first end coupled to the first conductive path downstream from the first choke device

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS10193488B2Methods and systems for reducing conducted electromagnetic interference

Publication Date: 2019.01.29 REGAL BELOIT AMERICA INC

AI summary

An EMI filter is described that includes an input having first and second input terminals, and an output having first and second output terminals. A first conductive path is defined between the first input and output terminals, and a second conductive path is defined between the second input and output terminals. The EMI filter also includes a first choke device coupled across the first and second conductive paths, and a first Y capacitor including a first end and a second end opposite the first end, the first end coupled to the first conductive path downstream from the first choke device. The EMI filter further includes a second Y capacitor including a first end and a second end opposite the first end, the first end coupled to the second conductive path downstream from the first choke device, and a second choke device coupled to an inverter output.