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“EMC DESIGN AND SUPPRESSION FOR DC MOTORS IN MILITARY AND

AUTOMOTIVE VEHICLES”

Presented by: James Muccioli Jastech EMC Consulting, LLC

Authors:James Muccioli & Dale SandersJastech EMC Consulting, LLC

The Southeastern Michigan IEEE EMC Society

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AbstractAs the next generation of vehicle technology emerges, the amount of electronic technology and electronic features increase the complexity of vehicle system integration. Vehicle power supplies are no longer simple battery supplied 12V or 24V systems with isolated electronic modules.

Next generation vehicles have more DC motors used in new applications. The ability to suppress EMI cost effectively requires more than just throwing a filter on the motor. To effectively meet requirements and cost criteria a system engineering approach is required from concept to production.

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1. Developing an EMC Test Plana. Requirementsb. Variables in EMC Test set-upc. Goals for each stage of testing

2. Motor design for EMCa. Housingb. End capc. Lead and terminal locationd. Bearings and bushingse. Brush design

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Description

Before discussing the process for developing good requirements, some important definitions must be established:

System: a set of components acting together to achieve a set of common objectives via the accomplishment of a set of tasks.

System Behavior: a sequence of functions or tasks, with inputs and outputs, that must be performed to achieve a specific objective.

Requirement: mandates that something must be accomplished, transformed, produced, or provided. The attributes of a good requirement are that it is unambiguous, understandable, traceable, correct, concise, unique and verifiable.

Traceable: in reference to requirements; a requirement is said to be traceable if one can identify its source. The source may be a higher level requirement or a source document defining its existence. An example would be if a component level requirement (weight, reliability) is traceable back to a vehicle level requirement.

Operational Concept: an operational concept is a shared vision from the perspective of the users and development participants of how the system will be developed, produced, deployed, trained, operated, maintained, refined and retired to meet the operational needs and objectives.

Systems Engineering Approach to EMC

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Systems Engineering Approach to EMC

1. BoundSystem for

EMC

3. Discover &Understand

Requirements

5. SelectBest

Solution

6. ValidateBest

Solution

2. IdentifySource of

Requirements

4. CreateAlternatives

Coordinate and Iterate as Required

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Step 1 - Bound System For EMC – Identify All External Items– Establish Interactions– Create System Context Diagram

Step 2 - Identify Source of Reqts– Collect Requirements– Sort Requirements by Classification

Step 3 - Discover & Understand Reqts– Discover System, Subsystem, and

Component Level Requirements– Brainstorm Scenarios– Benchmark Competition– Use Behavior Models to:

• Discover “Hidden” Interface Requirements• Resolve Conflicts between Models and

Scenarios

Step 4 - Create Alternatives– List Performance and

Operational Objectives– Prioritize Requirements with

Weighting Factors– Synthesize Physical Architecture

to Support Each AlternativeStep 5 - Select Best Solution

– Compare Proposed Systems Implementation

– Select Best SolutionStep 6 - Validate Best Solution

– Define Validation Plan– Linkage to Design Requirements

at each Level (vehicle, system, component)

Systems Engineering Approach to EMC

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EMI Specifications for Military and Commercial Vehicles

Military• MIL–STD–461E - EMI REQUIREMENTS, DESIGN and TEST• MIL–STD–464 - VEHICLE EMC & LIGHTNING REQUIREMENTS

Commercial (Automotive, Consumer)• SAE J551 and J1113 (series of dash-specs)• FCC Rules and Regulations, Title 47, Part 15, Subpart B• European Union (Various)• OEM EMC requirements

Today’s presentation will focus on the radiated emissions test setups on DC motors.

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Mil-STD-461E RF Requirement

Overview of MIL-STD-461E

CS101 POWER LEADS, 30 Hz to 50 kHz

CS103 ANTENNA PORT, INTERMODULATION, 15 kHz to 10 GHz

CS104 ANTENNA PORT, REJECTION OF UNDESIRED SIGNALS, 30 kHz to 20 GHz

CS105 ANTENNA PORT, CROSS MODULATION, 30 kHz to 20 GHz

CS109 CONDUCTED SUSCEPTIBILITY, STRUCTURE CURRENT, 60 Hz to 100 kHz

CS114 BULK CABLE INJECTION, 10 kHz to 400 MHz

CS115 BULK CABLE INJECTION, IMPULSE EXCITATION

CS116 DAMPED SINUSOIDAL TRANSIENTS, CABLES AND POWER LEADS, 10 kHz to 100 MHz

MIL-STD-461E

SUSCEPTIBILITYEMISSIONS

CONDUCTED(Cxxx Tests)

RADIATED(Rxxx Tests)

SUSCEPTIBILITYEMISSIONS

CE101 POWER LEADS, 30 Hz to 10 kHz

CE102 POWER LEADS, 10 kHz to 10 MHz

CE106 ANTENNA TERMINAL, 10 kHz to 40 GHz

• Conducted emissions requirements are designated by "CE---."• Radiated emissions requirements are designated by "RE---."• Conducted susceptibility requirements are designated by "CS---."• Radiated susceptibility requirements are designated by "RS---."

RE101 MAGNETIC FIELD, 30 Hz to 100 kHz

RE102 ELECTRIC FIELD, 10 kHz to 18 GHz

RE103 ANTENNA, SPURIOUS and HARMONIC OUTPUTS, 10 kHz to 40 GHz

RS101 MAGNETIC FIELD, 30 Hz to 100 kHz

RS103 ELECTRIC FIELD, 10 kHz to 40 GHz

RS105 TRANSIENT ELECTROMAGNETIC FIELD

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Mil-STD-461E RF Absorber Loading Diagrams

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Mil-STD-461E RF Test Setups

Conductive surface mounted EUT Non-Conductive surface mounted EUT

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Mil-STD-461E Antenna Positioning

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Mil-STD-461E Line Impedance Stabilization Network Schematic

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Automotive EMI / EMC Requirements

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CISPR 25 Radiated Disturbance for ALSE

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IEC International Standard CISPR 25

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CISPR 25 Artificial Network Schematic

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CISPR 25 Artificial Network

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EMC test plan goal should have repeatability and minimize test variability

EMC Test Plan

• Understand the EMC tests the lab will perform on your module.• Block diagram test fixture and DUT setup.• Take pictures of test setup.• Document the LISN being used.• Detail LISN ground straps and type of metal tape used by test lab.• Detail the type of 50 ohm loads to be used .• Document the test software used by the Lab.• Document pre-amps used by lab for your test and calibration.• Document antennas setup with pre-amps and cable routing in test

room.• Document the EMC test room and note if absorbers are placed

under test table.• Document how the test table is grounded to test room and size of

ground plane.

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1. Developing an EMC Test Plana. Requirementsb. Variables in EMC Test set-upc. Goals for each stage of testing

2. Motor design for EMCa. Housingb. End capc. Lead and terminal locationd. Bearings and bushingse. Brush design

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DC MOTORS IN MILITARY AND AUTOMOTIVE

• Military must meet shielding and filtering requirements for the frequency range from 10 KHz to 18 GHz.

• Automotive needs some type of shielding and filtering to meet EMC requirements from 100 KHz to 3 GHz.

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NOISE PROPAGATION INSIDE MOTOR

Metal motor case can act as a shield to block the radiation from

motor windings.

Electro-magnetic Interference (EMI) iscaused when the brushes break contact withthe commutator and the energy stored in themotor windings (magnetic field) creates anarc.

High RF field

Low RF field

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Housing Vent Holes

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Motor Housing Enclosure Joints

Rolled Steel Drawn Steel

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Motor End Cap

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To meet Mil EMC requirements the motor must have a metal or metalized end cap. This will help with containment of fields that can radiate around the plastic end cap and couple back onto the leads.

Noise can couple outside the motor casewhen using a plastic end cap.

A metal end cap works as a shield to contain the noise within the motor case.

Improved

Motor End Cap

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Motor Bearings and Bushings

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Brush Seated To Commutator

Brush contacts the commutator over very small surface area which results in large amount of arcing.

Brush contacts the commutator over very large surface area which results in small amount of arcing.

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Questions?

For more information and technical papers go to: http://www.Jastech-emc.com