Varistor-Based Interference Suppression for Electric Motor Actuators

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Solution Overview

Problem

Existing interference suppression arrangements for electric motors in motor vehicles require a large number of components to meet EMC and ESD protection standards, leading to installation space issues and high manufacturing costs, while often providing incomplete protection against both high-frequency electromagnetic interference and electrostatic discharges.

Innovation Solution

An interference suppression arrangement using varistors connected to the electrical connecting lines of an electric motor, which divert high-frequency currents and provide ESD protection without the need for coils, capacitors, or high-impedance resistors, ensuring efficient protection against both EMC and ESD.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple components (coils, capacitors, zener diodes, varistors, high-impedance resistors) are used for interference suppression, then EMC and ESD protection is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
ImproveEMC and ESD protectionVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple protection functions (EMC suppression and ESD protection) into a single integrated suppression arrangement that uses only two varistors. This merging of functions eliminates the need for separate coils, capacitors, zener diodes, and high-impedance resistors, thereby reducing component count while maintaining comprehensive protection

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The varistor-based suppression arrangement performs multiple functions simultaneously: it suppresses high-frequency electromagnetic interference (EMC) and provides electrostatic discharge (ESD) protection. The varistors are universally applicable for both protection needs, eliminating the requirement for specialized components for each function

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple components are used for interference suppression, then protection coverage is improved, but installation space requirements increase

Engineering Contradiction:
Improveprotection coverageVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

By merging EMC suppression and ESD protection into a single compact arrangement using only two varistors, the patent dramatically reduces the space required for interference suppression components while maintaining full protection coverage across both EMC and ESD domains

Inventive Principle:
Principle #5Merging (Combining)

3Object-generated harmful factors

If traditional suppression components (coils, capacitors) are used, then high-frequency interference is reduced, but manufacturing cost increases

Engineering Contradiction:
Improvehigh-frequency interferenceVSAvoidmanufacturing cost
Core Design Contradiction:
Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The patent replaces expensive traditional suppression components (coils, capacitors) with varistors, which are more cost-effective and simpler to manufacture. The varistor-based solution reduces manufacturing complexity and material costs while effectively suppressing high-frequency interference generated by brush sparking

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 varistor-based arrangement effectively reduces high-frequency electromagnetic interference and protects against electrostatic discharges, offering improved reliability and reduced component complexity, thus addressing the limitations of prior art while maintaining cost-effectiveness.

Implementation Method 1

high-frequency voltages can be derived by means of the capacitances of the first and second varistor

Methodology Applied
Scientific EffectParasitic capacitance: Parasitic Capacitance

Implementation Method 2

at least one electrical component connected to the electric motor, in particular electronics and/or a sensor system, can be protected against electrostatic charges

Methodology Applied
Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentEP2355312B1Suppressor assembly of an actuator with an electric motor
Publication Date: 2020.08.12 VITESCO TECHNOLOGIES GMBH
  • EP2355312B1 patent drawingFigure 1~2
  • EP2355312B1 patent drawingFigure 3~4
  • EP2355312B1 patent drawingFigure 5

AI summary

A noise suppression arrangement for an actuator with an electric motor comprises the electric motor with a housing that is at least partially electrically conductive, as well as a first and a second electrical connection lead. The first and second connection leads provide an electrical connection between a voltage source and the electric motor. Furthermore, the electric motor housing is connected to a part of the actuator that is at least partially electrically conductive. The noise suppression arrangement also includes a first and a second varistor. The first varistor is electrically connected to the first connection lead and the electric motor housing, and the second varistor is electrically connected to the second connection lead and the electric motor housing.The first and second varistors thus make it possible to protect at least one electrical component connected to the electric motor, in particular electronics and/or sensors, from electrostatic charges, and high-frequency voltages can be dissipated using the capacitances of the first and second varistors.