EMC Design and Suppression for DC Motors in - Jastech EMC ...

The Southeastern Michigan IEEE EMC Society
“EMC DESIGN AND SUPPRESSION FOR
DC MOTORS IN MILITARY AND
AUTOMOTIVE VEHICLES”
Presented by: James Muccioli
Jastech EMC Consulting, LLC
Authors:
James Muccioli & Dale Sanders
Jastech EMC Consulting, LLC
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Abstract
As 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 Plan
a. Requirements
b. Variables in EMC Test set-up
c. Goals for each stage of testing
2. Motor design for EMC
a. Housing
b. End cap
c. Lead and terminal location
d. Bearings and bushings
e. Brush design
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Systems Engineering Approach to EMC
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.
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Systems Engineering Approach to EMC
Coordinate and Iterate as Required
2. Identify
Source of
Requirements
1. Bound
System for
EMC
3. Discover &
Understand
Requirements
5. Select
Best
Solution
6. Validate
Best
Solution
4. Create
Alternatives
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Systems Engineering Approach to EMC
• 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 Alternative
• Step 5 - Select Best Solution
– Compare Proposed Systems
Implementation
– Select Best Solution
• Step 6 - Validate Best Solution
– Define Validation Plan
– Linkage to Design Requirements
at each Level (vehicle, system,
component)
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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
MIL-STD-461E
• 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---."
CONDUCTED
(Cxxx Tests)
RADIATED
(Rxxx Tests)
EMISSIONS
SUSCEPTIBILITY
EMISSIONS
SUSCEPTIBILITY
CE101 POWER LEADS, 30 Hz
to 10 kHz
CE102 POWER LEADS, 10
kHz to 10 MHz
CE106 ANTENNA TERMINAL,
10 kHz to 40 GHz
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
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
EMC test plan goal should have repeatability and minimize
test variability
• 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 Plan
a. Requirements
b. Variables in EMC Test set-up
c. Goals for each stage of testing
2. Motor design for EMC
a. Housing
b. End cap
c. Lead and terminal location
d. Bearings and bushings
e. 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
Electro-magnetic Interference (EMI) is
caused when the brushes break contact with
the commutator and the energy stored in the
motor windings (magnetic field) creates an
arc.
High RF field
Low RF field
Metal motor case can act as a
shield to block the radiation from
motor windings.
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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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Motor End Cap
Noise can couple outside the motor case
when using a plastic end cap.
A metal end cap works as a shield to contain
the noise within the motor case.
Improved
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.
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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
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