Download Jim Hendershot - Coil Winding Expo

WORKSHOP
Generator designs including
choices for hybrid vehicles
Time: 14:00 to 15:00
Presenter
James R. Hendershot
Life Fellow IEEE
Edited by
Prof. Ernie Freeman, FREng.
Fellow Royal Academy of Engineering (1987)
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Workshop Abstract:
Bosch
Generator designs including
choices for hybrid vehicles
ENERCON
Never before in history have generators of electricity
been more important to societies around the world.
Every principal method of creating electricity except
solar and fuel cells requires a rotating electro-magnetic
machine called a generator. There are three or four favorite machine types used for generating
electricity when rotated by some prime mover. Each has its pros & cons, some relating to their
performance and others relating to manufacturing methods and cost. Choices of generators are
reviewed with respect to a few important applications like hybrid vehicles,” more electric ship
propulsion”, “more electric aircraft,” “wind turbines” and “flywheel batteries”.
Very large generators for power plants are best served by wound field synchronous generators
with practically no other option so this application is not studied. A comparison of permanent
magnet synchronous, reluctance synchronous, switched reluctance and Induction asynchronous
machines are discussed and compared for the current popular generator applications. Some
important design features are discussed in addition to cooling requirements.
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Workshop Presenter:
James R Hendershot
Jim has over 40 years experience in practical hands-on PM & SR brushless motor design, manufacturing
and development. With past key employments at United Technologies, General Motors, Clifton Precision,
Berger Lahr & Pacific Scientific, he has designed hundreds of brushless motors for computer disc drives,
servo systems, high speed machine tool spindles, traction drives, hybrid vehicles, micro-turbine and diesel
generators. He has written numerous technical papers, publications and presented tutorials on many different
electric motor topics. Hendershot is the co-author with Professor TJE Miller for two of the leading design books on Permanent books on
Permanent Magnet Motor and Generator Design (ISBN 1-881855-03-1, 1994 & ISBN 978-0-9840687-0-8, 2010).
Jim teaches detailed motor design training courses (including workshops) at public venues, conferences and custom designed workshops
tailored on-site for companies around the World. Jim Hendershot holds a B.S in Physics from Baldwin Wallace University in Berea Ohio
along with additional E.E. & M.E. engineering studies at Cleveland State University as well as graduate courses at Case-Western
University in Cleveland Ohio. He specializes in the design, analysis, sourcing, manufacturing and teaching of both electro-magnetic and
permanent magnetic devices. In addition to continuing studies in magnetics and electric machines.
Jim has enjoyed a long and rich association with Dr. Tim Miller, founder of the SPEED Consortium at the University of Glasgow
combining Jim’s practical hands-on motor design skills with TIM’S theoretical knowledge and research
For the past few years Jim has also been associated with Infolytica Corp, Prof. Dave Lowther (of McGill University), Prof. Ernie Freeman
retired from Imperial College, London and their staff for continued development and research involving the design and research for
electric motors and generators.
Jim Hendershot developed a Dyno-Kit for teaching electric motor drives used by over 120 US Universities and Colleges for Prof. Ned
Mohan of the University of Minnesota. These are used for the lab portion of their Electric Drive Courses.
Jim Hendershot has created a series of 36 electric machine design lectures for the University of Minnesota, funded by the US Navy
Research Labs that are available on YouTube. (9 to 10 hrs. of lectures covering all aspects of practical electric machine design).
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Introduction:
Most electric machine discussions center around motors
Faraday first discovered the generator in 1831
Tesla did not invent the Induction motor until 1887
Today only two electricity sources do not require a generator
Fuel Cell & Solar
All others require either a linear or a cylindrical generator
(Batteries& capacitors are used for storage not generating)
Generators convert mechanical input power
into electrical output power.
Lets have a look at the current electricity generation choices
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Sun can produce electric power
Solar Panels
NO SUN,
NO POWER!
Mirrors focus suns heat to produce
steam for electric turbine generators
Betaray
>70 %
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Fuel cells require no energy conversion generator
Toyota cell
UK Carbon Trust
Ballard Bus Fuel Cell
Toyota Fuel Cell
Fueled by Hydrogen or Natural Gas
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Wind energy produces
electric power
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Power must be stored when No Sun and No Wind
Hydro Energy storage
Chemical battery
storage
Chemical battery storage
Flywheel
battery
New Tesla
Battery pack
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Historical generating
systems for electricity
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Model of Faraday’s Generator
National Museum of Nature
and Science, Tokyo, Japan.
CIRCA 1831
It consists of a copper disk between the poles of a horseshoe magnet. When the disk is
turned with the crank, a current of electrons flows radially from the center of the disk to the
rim, due to Faraday’s law of induction. This is picked up by a springy contact pressed against
the rim of the disc. The current flows through an external circuit & returns to the center of
the disc through the axle
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Steam engines and steam
turbine driven DC generators
Edison
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Prof. A. Binder
TECHNISCHE
UNIVERSITÄT
DARMSTADT
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Three Gorges Dam power plant in China
(32) 700 megawatt generators
Hydro-Electric
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Power plant generators, Air, Water or Hydrogen cooled
Air Cooled to 335 MVA
Hydrogen cooled to 630 MVA
Water cooled to 800 MVA
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Normally driven by coal
fired steam turbine
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MORE POWER
PLANT
GENERATORS
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Wound field synchronous generator (brushless exciter)
(48) slot stator, with (2)
coils/pole/phase
(8) pole wound rotor,
with brushless exciter
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TYPICAL STAND-BY GENERATOR
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AC Induction motor with (3) phase wound rotor
Large versions used for Wind Turbine generators (MW size)
ranges)
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Cut-A-Way of a synchronous generator with PM brushless exciter
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Wound rotor AC Induction machines
Rotor wound with three phase
windings connected to three slip rings
and brush assemblies
More expensive than caged rotors
Lower slot fills than caged rotors
Torque vs speed vs
rotor resistance
Used in the past for lifting heavy loads
requiring high starting torques
Used for wind turbine generators
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21st Century generating
systems for electricity
including renewables
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Turbine driven generator
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Switched Reluctance startergenerator for 20,000 rpm gas
turbine engine
(4) pole
rotor
(6) pole fuel cooled stator
General-Electric & Sundstrand
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Switched Reluctance seem to be popular for large off road machine
5900 liter Hybrid front end loader
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Combined Cycle Natural Gas & Renewables like Wind & Solar
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Tidal and ocean wave generation
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Generating Electrical Power from Tidal Energy
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Most three most common wind turbine generators
Doubly fed AC induction machines with slip rings
(1500 to 1800 rpm)with step up (3) stage gearing
Direct drive permanent magnet (5 to 20 RPM)
Medium speed permanent magnet with single or
two stage gearing (100 to 500 rpm)
There are many variations of the PMGs
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Direct drive PM synchronous generator
Unexpected high down times
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Most common wind turbine generating system
Proven design with long history
and lowest cost to install.
(Unexpected least down time)
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Wind Turbine PMG, medium speed with gear box
Perhaps the most promising wind
turbine generator concept, medium
single or double stage gear box &
much lower magnet cost.
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Enercon E 126 direct
drive wind turbine
with no magnets
6.5 MW
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Enercon 6.5 MW stator winding
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Enercon 6.5 MW Rotor Windings
Includes Slip Rings and Brush Rigging @ 10 to 20
rpm
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Enercon 6.5 MW Rotor & Stator Coils
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Thermal-acoustic power generator
Voice coil in a PM field
attached to a titanium
diaphragm generates
electricity when exposed
to heat or noise
Titanium Diaphragm
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Fellows Pat. # 6910332
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THERMAL LINEAR GENERATORS
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Thermal-acoustic power generator
Paul Riley, University of Nottingham
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Linear PM Generator driven with two cylinder IC Engine
Prof. Valeri Golovitchev
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TRANSVERSE FLUX PM GENERATOR
CAN BE GANGED UP ON A
SHAFT FOR DIRECT DRIVE
WIND TURBINE.
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Toyota free piston engine linear generator
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Generating electric power for
vehicles, cars, trucks, buses,
delivery vans farm tractors
& off road equipment
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Conventional alternators have limited output for newer vehicles
Typical “claw” rotor
High powered alternator
Added magnets
Patent # 6,903,485
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Claw Pole alternator (0ver 80 million produced in 2014 not counting trucks)
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Multiple alternator installations for more E - power
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Hi performance Switched Reluctance IC engine generator
Off road vehicles& Semis require
greater than 2.3 to 3.0 kW from
heavy duty claw pole alternators
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PAT # US 7755308
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Homopolar Hybrid generator (PMHH)
High power density brushless PM generator with no
bearings (coupled directly to IC engine crankshaft)
USED FOR MILITARY VEHICLES
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Electric machine choices for
generators & some design tips
Some of the following slides display output results taken from th MotorGenerator simulation tool used by this author called MOTORSOLVE with
new generator simulation features, by Infolytica.com
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Generators with (3) different
rotor configurations using similar
stators and three phase windings.
IM
RSM
SRM
SR machines can be used as
generators but the regulation
of the voltage more complex
than the other machine types.
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All three machines typically
utilize boost converters for
voltage, frequency & power
regulation.
IPM or
SPM
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ELECTRIC MACHINE POWER DENSITY COMPARISONS
TESLA 4.5 kw/kg (225 kw peak for 30 sec??)
New TESLA 4.34 kw/kg (300 hp 115 lbs peak)
BMW i3 = 2.5 kw/kg (at 125 kw max)
Siemens 5 kw/kg
Aero PM motor
(260 kw @ 50 kg)
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How does one choose the best machine
for a generator application?
The selection has a lot to do with the application but don’t forget
the following points:
The highest peak & continuous power efficiency is achieved with a
Permanent Magnet Synchronous machine (motor or generator).
Some applications cannot support the cost of magnets
Increasing speed reduces machine size & increases power density
Slip rings and brushes can be acceptable if rpm is very low
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Maximum flux densities of materials limit performance
No matter which machine you choose for a generator
its torque density is limited by two important magnetic
materials.
1-Hard materials (permanent magnets) can only produce a
maximum flux density of 1.4 tesla
2-Soft materials (electrical steels) become saturated at
maximum flux densities in the range of 2.1 to 2.4 Tesla
I offer each of you a challenge to invent new materials
A new material with a negative permeability would be a good
start, then higher temperature super conductivity materials
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Stator diameter vs number of poles
(Fixed rotor diameter)
When number of poles is doubled, the back iron
flux is cut in half. Example below is with fixed
rotor diameter which reduces the stator OD
Yoke thickness & stator O.D. increases with decreasing
pole numbers with a fixed stator slot depth & rotor OD
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AC Induction machine with either aluminum
or copper shorted turn rotor
Rotor & stator cross section
Three phase winding layout
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Wound rotor AC Induction machines
Rotor wound with three phase
windings connected to three slip rings
and brush assemblies
More expensive than caged rotors
Lower slot fills than caged rotors
Torque vs speed vs
rotor resistance
Used in the past for lifting heavy loads
requiring high starting torques
Used for wind turbine generators
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Doubly fed Induction generator
Rotor Details
Rotors with ducts for cooling
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Slip Rings & Brushes
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Torque vs. speed of AC Induction machine
(constant voltage and frequency)
Motoring
Generating
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AC Induction motor pole number greatly influences
motor size and mass (under ~ 1700 Nm)
Also applies to RSM
motors (JRH)
Drip-proof force ventilated
Totally enclosed blower cooled
Drip-proof force ventilated
Totally enclosed blower cooled
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~1700 NM
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Reluctance Synchronous generators
Standard AC Induction stator laminations
Standard AC induction phase windings
Manufactured with existing AC machine machinery & tooling
Synchronous performance with no rotor slip
Driven with existing AC Induction inverters (with software
modification)
No expensive permanent magnets in rotor
Only change is a new rotor design
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RSM rotor examples
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Reluctance Synchronous machine
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Reluctance synchronous phase windings
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2010 Toyota Prius PM
Synchronous Generator
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2010 Toyota Prius generator components
Resin Encapsulated stator
IPM rotor ass’y (8 pole)
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Generator output voltage and power
The internally generated voltage emf in a single phase of
a synchronous machine is not usually the voltage
appearing at its terminals. It equals to the output voltage
V only when there is no armature current in the
machine. The reasons that the open circuit voltage is not
equal to the output voltage V are:
1. Distortion of the air-gap magnetic field caused by the
current flowing in the stator (armature reaction)
2. Self-inductance of the armature coils
3. Resistance of the armature coils
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Two rotor configurations of Permanent Magnet Generators
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4PH SR
8-6
3PH SR
6-4
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3PH SR
6-8
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More PM Synchronous Generator configurations
Inside Rotors
Ring Magnet
Spoke IPM
Outside Rotors
Bread-loaf SPM
Radial Arcs
V-Pole IPM
Parallel Arcs
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IPM brushless machine
mounted to IC engine
Vehicle traction and assist
24 slot stator
concentric coils
Replaces alternator for battery
charging
Replaces engine starter by
quickly & quietly cranking
engine during stops
(18) poles
Also used to dampen
crankshaft vibrations of IC
engine leading to smoother
ride.
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Chevy Volt Motor
and generator
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We are not going to be able to get along without
generators for electricity so lets learn more about
their possibilities and capabilities.
Thank you for attending
JRH
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