SMMA
2006 Fall Technical Conference
November
1-3, 2006
Marriott St. Louis Airport Hotel
Program
* SMMA Member Company
Thursday, November 2, 2006
Salon E
The EMERF Lamination Steels Third Edition CD-ROM is scheduled for completion
by the start of the SMMA 2006 Fall Technical Conference. This presentation
will provide a summary of the information on the completed disk, and will
point out some of the interesting features of this publication.
In today's high performance and cost competitive world of motion control,
system designers and machine builders constantly search for servomotors that
have the highest possible continuous torque output and power density along
with the lowest possible cost. Since motor volume and cost are related (i.e.
less volume, less cost), motor designers constantly search for ways to increase
their motors continuous torque output along with its power density. As described
in this paper, one way to significantly improve a motor's power density by
as much as 25% is to pot its stator winding using a thermally conductive epoxy
as compared to impregnating the winding using a typical varnish. Furthermore,
this paper also describes how the "Cut-Core" or "Segmented-Core"
stator design reduces the stator's electrical resistance and provides an additional
25% increase in power density for a given motor volume compared to employing
the more traditional "Solid-Core" design.
Rare earth-iron-boron is now a very mature product technically, with its well-known
Nd2Fe14B alloy composition well optimized and the basic global patents virtually
gone. Growth in applications for isotropic bonded Nd-Fe-B magnets is now driven
by cost reduction rather than performance improvement, this growth now being
dominated by Chinese producers. But there is currently high volatility in
the pricing of critical raw materials, particularly the rare earths. So it
is useful to evaluate the cost benefit (or penalty) to the magnet's operating
performance of varying the concentration levels in the alloy of such elements
as neodymium and cobalt. Several major application opportunities have been
identified for the replacement of ferrite with bonded NdFeB, whose performance
requirements are linked to the required constituent elements for the magnet
alloy, and hence to the cost sensitivity of these elements.
The 0.5 slots/pole/phase fractional winding design offers several interesting
performance trade-offs to the more traditional 1.0 slots/pole/phase integral
winding. Winding resistance and inductance differences and their affect on
motor performance are modeled. Less obvious is the affect on air gap flux
distribution, Back-EMF wave shape, and torque ripple. Motors were built and
tested to compare to each other and the predicted performance values. To add
interest, a second fractional design with wider iron circuit widths was built
to study the trade-off between losses in the copper and iron.
In this presentation, a method of determining the initial position of the
rotor of a permanent magnet synchronous machine using signatures in torque-ripple-induced
vibration is described. Although requiring a vibration sensor, the method
requires no knowledge of machine parameters, is applicable to both surface-
and buried-magnet machines, and can be used under no load. Hardware validation
has been performed using a surface-magnet machine, wherein a maximum error
of 2.1° (electrical) has been achieved using a start-up routine that requires
50 ms to complete.
11:30-12:00
Analyzing and Comparing Motor Efficiencies in Variable Speed Drives, Daniel
B. Jones, President, Incremotion Associates Inc.*
One of the more important activities in speed controls is to evaluate overall
motor efficiency performance. The traditional one speed and two speed motors
are being replaced by variable speed drives (VSDs). A new software evaluation
tool, MEAD, now allows the user to perform detail analyses with respect to
torque and speed for permanent magnet (PM) electric motors.
MEAD allows the motor designer or user to analyze and segregate the various motor losses and to then display the resulting efficiency, loss and motor temperature values, plus operating costs in a variety of 2D and 3D plots. Additionally, two motors can be compared using a subtraction formula to visually display the performance differences. Inputs to the program can be accepted from actual motor test data or from reliable motor data sheets.
1:00-1:30 Design
Strategies to Facilitate Commercialization of the Copper Rotor Motor, E.
F. Brush Jr., J.G. Cowie and D. T. Peters,
Copper Development Association, presenter Dr. Brush
At this conference in 2003, the Copper Development Association Inc. reviewed
ongoing research and development work toward taking advantage of the high
electrical conductivity of copper by substituting copper for aluminum in the
rotor squirrel cage to substantially increase the electrical energy efficiency
of the induction motor. The effort was directed at small and medium size integral
horsepower motors for general industrial, commercial and residential application.
The manufacturability of a copper rotor motor had long been a barrier to its
adoption in large numbers. Therefore advancements to high pressure die casting
of the relatively high melting temperature copper undertaken by CDA were briefly
reviewed. CDA had shown that use of nickel base alloy inserts operated at
elevated temperature greatly extended the life of the die components from
a few shots with conventional die steels to thousands of shots in the new
system for a cost effective manufacturing process very much like that used
for the aluminum rotor familiar to all motor manufacturers. Work done jointly
with several motor manufacturers to generate the initial data on motors built
with die-cast copper rotors cast by CDA was reviewed. The rotors laminations
supplied by the manufacturers were those designed for the conventional aluminum
rotor. Data for these copper direct substituted rotor motors showed that the
I2R loss in the rotor had been reduced on the order of 40% resulting in an
overall efficiency increase of 1 to 5 percentage points. These motors also
showed lower operating temperatures, higher slip, slightly higher rotational
speed and reduced starting torque characteristics.
This paper reviews the considerable advances in copper rotor motor design in the past three years that have led to commercial introduction of high efficiency copper rotor motor product lines in the range of 1 Hp to 20 Hp and above by several manufacturers. These products meet EPAct and EFF1 efficiency standards and one manufacturer has introduced a die-cast copper rotor line exceeding NEMA Premium. Copper die casting is now recognized as very doable using the CDA developments or variants as well as proprietary technology of die casters supplying copper rotors to European motor manufacturers. The data presented here will focus on motors specifically designed to best utilize high conductivity copper in the rotor. These designs have generally adjusted the starting torque and in-rush current characteristics to meet IEEE performance specifications. The smaller motors in the product line have proved to be satisfactory with direct substitution of copper for the aluminum with no other design changes apart from increasing the quality of the electrical steel. Motors above about 1.5 Hp generally employ modified slot geometry and substantial redesign of the stator and winding patterns. Markedly lower operating temperatures and flatter efficiency-load curves are observed. It is interesting that manufacturer design studies have shown that copper rotor designs to meet a given efficiency often allow a smaller frame size than the aluminum design. Despite the higher density of copper, smaller, lighter motors are realizable with the copper rotor. The influence of the recent sharp increases in copper prices compared to aluminum increases on payback times at reduced energy consumption for high duty cycle copper rotor motors is discussed.
1:30-2:00
Servomotor Temperature Considerations, John Mazurkiewicz, Product/Marketing
Manager, Baldor Electric Company*
A servomotor's temperature should be determined and observed, because life
and therefore machine reliability depends upon this. Determining temperature
will make sure the application gets the most from the servomotor. A servomotor
with a velocity profile in an application dissipates a certain amount of power.
The motor's thermal resistance is a measure of how effectively the motor rids
itself of generated heat. Using these figures, we can easily calculate the
motor's temperature rise. With the motor's thermal time constant, the thermal
profile of a servomotor can be plotted. This profile can be classified by
whether power is applied constantly or for an on-off power duty situation.
Thus total servomotor temperature may be determined.
2:00-2:30
Commutation Analysis of PM DC Motors, William H. Yeadon, President and
Brad Frustaglio, Design Engineer, Yeadon Energy Systems Inc.*, presenter,
Mr. Frustaglio
This paper covers a method for determining the commutation properties of a
PMDC motor. It takes into account the effect of the self inductance, resistance
and the voltage generated in the commutating coil as it varies its position
during the commutation cycle. A method for determining the optimum brush shift
angle is then shown.
2:30-3:00 A
New Testing Rig for Evaluating Motor Reliability and Endurance, Emmanuel
B. Agamloh PhD, Advanced Energy Corp.*
It is estimated that about 60% of the U.S. integral horsepower motor population
is rated between 1 and 5 hp. Also, about 15 million fractional horsepower
motors are manufactured globally every day. Small motors therefore comprise
a large percentage of the total U.S. motor population. Many of these motors
find applications as integral components of various original equipment. These
original equipment manufacturers (OEMs) often find that the ability of their
equipment to perform and its reliability are intricately linked with the reliability
of the motor. Following persistent requests from OEMs to evaluate the endurance
of the motors used for various applications, Advanced Energy has designed
and built a new testing rig to subject small motors to reliability and endurance
testing.
The endurance and reliability tests are used to measure the long term performance of the motors and consequently the equipment. These tests are often required during major changes in the design of the OEM motor driven products. These changes include warranty audits, quality control issues, loss of supplier or change in supply conditions, etc.
The reliability/endurance rig was designed to enable testing of a reasonable sample of motors for a given application over a specified period of time (usually several weeks) with little or no attendance. The rig is equipped with testing bases for 10 motors simultaneously with fan, flywheel or dynamometer loading. This is expandable to test 20 motors simultaneously with fan loading. The test and load motors are controlled with a computer in a LabView environment. This paper presents the design of the new setup to evaluate motor reliability and endurance. The testing methods and procedures as well as case studies are described.
3:00-3:30 Networking Break with Table Top Exhibits, Salon III-V
3:30-4:00
Designing Squirrel Cage Rotor Slots with High Conductivity, J.L. Kirtley
Jr. and E.F. Brush, Copper Development Association, presenter
Darryl VanSon
Because copper has higher conductivity than aluminum, cast copper rotor induction
motors should have higher efficiency than their cast aluminum counterparts.
However, there are considerations beyond efficiency: the higher conductivity
of copper also reduces starting torque. Proper shaping of conductor bars can
improve starting torque and reduce 'stray' load losses. This paper describes
an investigation into ways of taking advantage of the higher conductivity
of cast copper in rotors of induction motors. Deep bar and multiple cage effects
are useful in design of such machines. It is shown that a useful understanding
of how different slot shapes work may be developed through the use of frequency
response curves that describe rotor slot impedance as a function of rotor
frequency. Good starting, running and stray loss characteristics can be identified
in such frequency response curves.
4:00-4:45
Revisions to UL Motor Standards, Frank Ladonne, PDE Rotating Machinery
and Overcurrent Protection
UL will be undertaking a substantial revision of its motor Standards. This
revision is intended to result in Standards and requirements that are more
reflective of current and emerging technologies such as brushless DC (BLDC)
or electrically commutated motors (ECM), servo motors, stepper motors and
the like. In addition, this revision is intended to result in Standards that
represent the most current technical philosophies. UL envisions this revision
as resulting in a series of Standards where the parent Standard, the first
in the series, contains requirements that apply to all rotating machinery
and the subordinate Standards would each address a specific construction,
i.e., servo and stepper motors, generators, impedance protected motors, etc.
Presently, UL has created 5 Standards and is soliciting comments prior to
balloting and acceptance. These are:
" 1004-1 - Rotating Machinery
" 1004-2 - Impedance Protected Motors
" 1004-3 - Thermally Protected Motors
" 1004-4 - Electric Generators
" 1004-5 - Fire Pump Motors
UL is in the process of drafting 4 additional Standards. These will be:
" 1004-6 - Electronically Protected Motors
" 1004-7 - Servo and Stepper Motors
" 1004-8 - Inverter Duty Motors
" 1004-9 - Motor Rebuilder's Program
Mr. Ladonne will speak to the scope, content and philosophy of the new Standards
and will make himself available to answer questions.
6:00 Reception and Dinner, Salon B-C
Friday, November 3, 2006
Parallel Sessions from 8:00-9:50
Salon E
8:00-8:30 Thermal Response of Electric Machines, Adrian Perregaux, Marketing Director, Magsoft Corp*. As electric machine demands continue to be more and more stringent, it clear that the design needs to adequately address the requirements of more than one discipline of physics. Electric machine failure due to an incorrect thermal design can be costly and devastating to program development. Motor-CAD is a revolutionary new simulation software which adequately simulates and predicts the thermal behavior of an electrical machine. It further allows one to quickly explore the various types of cooling options which may be either allowed or required depending upon the product specification. This paper will discuss thermal physics, thermal physics as it applies to electric machines and the use of Motor-CAD to specifically review and assess the thermal response of electric machines.
8:30-8:40 Travel Time
8:40-9:10 Magnetic
and Circuit Simulation in Brushless Motor and Drive Design, Richard T.
Walter, Consultant, Walter Technology Resources*
This presentation demonstrates the benefits of using magnetic and circuit
simulation simultaneously in motor and drive development. An electric scooter
hub-motor is used as an example. This motor is a fractional slot pitch, 3-phase
design with a PWM controlled drive. Both the motor and drive were modeled
using MagneForce Software Systems' BLDC motor simulator. This simulator includes
a finite element magnetic model and a SPICE circuit model to solve the design
problem. The designer can enter and edit the rotor and stator geometry, the
materials, the winding, and several mechanical factors using an intuitive
user interface. He then can select or design the drive topology, component
parameters, commutation sequence, and the PWM control scheme. The program
will output performance, losses, parameters, and waveforms. Other outputs
include cogging torque, torque ripple, iron losses, and demagnetization predictions.
Most outputs are displayed in both graphical and tabular form. The predicted
performance correlates well with test results.
9:10-9:20 Travel Time
9:20-9:50 Impact
of Software and Hardware Advances on Motor Design Tools, Behzad Forghani,
Vice President, Infolytica Corporation
The complex geometry of a motor and the non-linear behaviour of the materials
make it necessary to use a field based solution system when accuracy of the
motor performance parameters is important. Field based solution systems exist
in general purpose FEA tools and these tools have become commonplace when
designing a motor. With the ever-increasing power and speed of personal computers,
at an affordable price, it is now routine to perform finite-element simulations
since solution times have come down significantly. Advances in software design
have made it possible to build very powerful and sophisticated programs. An
easy to use alternative to a general-purpose FEA tool is a system that uses
the FEA engine but has knowledge built into it about motors. The objective
of this paper is to introduce a new motor design tool that takes advantage
of recent advances in software design and hardware performance.
Salon
I-II
8:00-8:30 An
Update of Sintered NdFeB Magnets , Mike Guthrie, Director of Engineering,
Quadrant Technology
The manufacturing technologies of sintered NdFeB have changed from those of
the 80's and 90's. Today's methods have evolved to allow noticeable property
improvements and price reduction. Higher induction and greater coercivity
are achievable while allowing greater resistance to corrosion and often a
reduction in the required magnetizing field. A brief look at the world of
patents and licenses is presented. (However no explanation will be attempted.)
China continues to increase its share of the market. While improved manufacturing
techniques and reduced labor expenditures continue to reduce the cost of NdFeB
materials, recent changes in raw material prices work to erode some portion
of those savings. This new landscape of processes, materials, and costs promotes
new design opportunities for established and emerging products.
8:30-8:40 Travel Time
8:40-9:10
Recent Improvements in Sintered NdFeB from China, Steve Constantinides,
Director of Technology, Arnold Magnetic Technologies Corp.*
Chinese manufacturers of NdFeB magnets have been able to complete effectively
from a pricing standpoint for the last two decades. However, only in the last
one to two years has the quality of magnets supplied by these manufacturers
reached world class status with excellent high energy and temperature performance
coupled with improvements in corrosion resistance. Examples of these improvements
will be provided along with test methods and a discussion of magnetic and
testing standards.
9:10-9:20 Travel Time
9:20-9:50
Bonded Magnets - Why are we Competitive?, James
Bell, PhD, Magnet Applications Group
Over the last few years there has been an immense change in
the U.S. magnet manufacturing business. First, the sintered ferrite business
was decimated by Chinese manufacture and then fairly rapidly followed by the
sintered neo business. One area that has remained somewhat immune from Chinese
competition is the bonded magnet market and particularly products based on
bonded neo. The aim of the talk is to examine why this has happened and also
to look at the current and future trends in China, which may be indicating
that we have reached the peak in terms of pressure on U.S. magnet manufacturing
businesses.
9:50-10:20 Networking Break with Table Top Exhibits, Salon III-V
Back in Single Session
Salon E
10:20-10:50
Design of a High Pole-Count Direct-Drive Dynamic-Rotor Techniology Motor,
Robert Klimo, VP Engineering, Dynamotors Inc. Many
industrial variable-speed applications have low final output speeds that require
mechanical gear reducers to accommodate the normal running speeds of conventional
induction motors. Replacing the induction motor-gear reducer combination with
high pole-count variable speed direct-drive motor greatly simplifies the design
of the application and potentially reduces the cost and weight of the application.
This presentation explores the design of a direct-drive motor and presents
results obtained using finite-element magnetic analysis. Also, the DMI Dynamic
Rotor Technology motor with a self-contained speed controller eliminates the
need for a separate adjustable frequency inverter drive controller that is
usually used with the convention induction motors.
10:50-11:20
A Fundamental Comparison of Radial and Axial Motor Performance, John
Petro, President, NovaTorque Inc.*
Motors based on the traditional radial geometry have dominated the electric
motor industry for over 100 years. However, there has been a growing interest
in axial geometry motors in recent years. This paper looks at the basic fundamental
design issues and differences between two approaches to motor design. Performance
per unit size and a number of other motor metrics are examined and compared
for these two different motor geometries. Additionally, advantages and disadvantages
of each type of motor are presented. Both conventional wound and segmented
core (cut core) radial motors are analyzed, and both traditional flat disk
and conical configurations of axial motors are also discussed. This paper
provides the user with an excellent basis for choosing one design over the
other based on different application requirements.
11:20-11:50
FreedomCAR Motor Development, John McKeever, PhD, Senior R&D Staff
Member, Power Electronics and Electric Machinery Research Center for the Engineering
Science and Technology Div. of Oak Ridge National Laboratory
The FreedomCAR program under the Department of Energy is tasked with furthering
the development of hybrid, plug in hybrid and ultimately fuel cell vehicles.
To this end the Power Electronics and Electric Machinery group at Oak Ridge
National Laboratory is working on future power electronic and electric machinery
technologies. Key to the marketplace acceptance of these advanced vehicle
systems are the electric motors used in the traction drive systems. These
must overcome cost, size, weight, and volumetric limitations. The trend in
motor development efforts for vehicular applications is towards high power
density permanent magnet machines. Innovative interior and surface mount magnet
designs are being explored as well as advanced magnet development for higher
temperature operation. Motor designs for these applications cannot be developed
in a vacuum as a systems approach must be utilized in looking at the design
impacts on the entire vehicle. Currently projects are underway working to
increase flux density, overcome mechanical limitations to higher speeds, reduce
losses and extend the constant power speed range of motors, all the while
keeping cognizant of how these motor technologies affect battery and power
electronics requirements.
11:50 Adjournment
10.20.06