motorsolve analysis of the 2010 toyota prius traction motor. · pdf filerotor punching...

Hendershot 2015 Copyright 1

MotorSolve analysis of the 2010 Toyota Prius Traction Motor.

Presented by: James R Hendershot

Location: Hilton Rosemont, Chicago O’Hare

Date: Oct. 27, 2015


Presenter:James R Hendershot

Jim has over 40 years experience in practical hands-on PM & SR brushless motor design, manufacturingand 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 dieselgenerators. 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).


For thousands of years man could only walk here and there.

By 4000 to 5000 BC man began to ride horses

Around 2000 BC horses were used to pull carts and carriages

Early US settlers used horse & oxen drawn large wagons to“go West” (Like modern RVs & campers)

In 1605 horse drawn carriages were used on the streets of London.

By 1640 the London horse drawn carriages added springsfor comfort and with a driver.


In the late 19th and early 20th century, electricity was the preferred power source for automobile propulsion. US had no highway systems because passenger trains were used for long distance travel.

Gasoline was known but no infrastructure available

Steam powered cars were also tried.

By 1920 thanks to Henry Ford, IC engine improvements and the growing petroleum infrastructure, thanks to John D Rockefeller, gasoline power dominated automobiles until this present day.

Introduction


History summary of automobile propulsion:

1768 French steam engine powered car by Nicolas Cugnot

1832 Robert Anderson ran first electric motor driven car

1885 Karl Benz made first 4 wheel gas powered car

1888 First noted (4) wheel E-Car, Flocken Elektrowagen

1893 First American car was developed by Charles Duryea

1897 Stanley Steamer in Newton MA, sold 200 cars

1908 Ford Model-T introduced (Internal combustion gasoline powered engine)


Early examples of E-Vs1888Flocken

1910POPE

1907Detroit

1912Edison

1918Woods

First lead-acid storage batteries developed in 1859Frenchmen namedGaston Planté

Limited gasoline availability andcars needed for only short trips.Trains used for long distances)


First (serious?) electric car since in nearly 100 years

EV1 by General Motors


EV1 by General Motors

Production years 1996 to 1999EV1s total produced total 1117 carsRange 70 to 90 miles per chargeMotor type, (3) phase aluminum rotor

AC induction motorMaximum output power = 103 kWPeak output torque = 149 NmBase speed = 6500 rpmMax speed = 13000 rpm


Toyota Motor Car Corp. EV or Hybrid development

Sometime in the middle 90s, Toyota began development of a hybrid electric vehicle to compete with the GM EV1.

First production in Japan in 1997 (before the EV1 was cancelled by GM in 2003.)

Toyota PRIUS first sold in the USA in 2003

Second generation PRIUS sold in USA in 2004

Third generation PRIUS sold in USA in 2010

Fourth generation PRIUS in USA scheduled for 2016


World hybrid Hybrid/EV sales 2003 to mid 2015

Total world production of hybrid or electric vehicles since 2003 = 3,540,199

Total world production of Toyota’s share = 2,487,564 ( 70%)

Total world production of Prius share = 1,731,717 (49%)

755,847 difference from other hybrid models designed & sold by Toyota such as, Camry, Avalon, Highlander & Lexus.

Hendershot 2015 Copyright12

Electric traction motor optionsfor hybrid and EV vehicles.

IM

RSM

IPM orSPM

Cross sections of electric machines by:

Switched Reluctance New rotor & stator

IM, RSM & IPM/SPM use similar stators &phase windings with different rotors


No matter which machine you choose for a motor/generatorits 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

Maximum flux densities of materials limit performance


Specific power density of current piston engines, turbines & electric motors

Cooling and efficiency are very important for electric propulsion


Power density of modern EV traction motors


ELECTRIC MACHINE POWER DENSITY COMPARISONS

TESLA 4.5 kw/kg (225 kw peak for 30 sec.)New TESLA 4.34 kw/kgBMW i3 = 2.5 kw/kg (at 125 kw max)

Siemens 5 kw/kgAero PM motor(260 kw @ 50 kg)


Review of the Toyota Prius PM-AC traction motors

Toyota selected the PM-AC synchronous motor because it has the highest power density, highest power factor, highest efficiency and easiest to cool of any known electric machine. (Perhaps a bit more expensive than that other choices due to use of rare earth magnets.

However if AC Induction motors are used they must use copper rotors which increases their costs also. (The extra difficulty of rotor cooling and lower power factor tends to offset the magnet cost of the PM-AC machines.)

There are two types of PM-AC synchronous machines, SPM & IPM.

IPMs were chosen for several important reasons for automobile traction.Wide constant power speed range rangeRobust rotor without additional retainmentLower cost rectangular permanent magnets (no grinding required)Added reluctance torque output from same source current for magnet torque


Two types of PM-AC synchronous machines, SPM & IPM.


Prius 2003 IPM style (8 poles) Prius 2004 IPM style (8 poles)

The magnets & pole tops are retained against centrifugal forces by thin websat the magnet ends. Careful stress analysis is required as well as field solutionsto minimize flux leakage. (Said to be as high as 20 % leakage)


Toyota IPM rotor dimensions


Rotor Punching comparison for IPM Toyota electric traction motors

Actual Prius rotor punching has mass reduction pockets that also facilitate cooling. This can be modeled by importing a cad created rotor DXF file in MotorSolve or in MagNet.


2010 Toyota Prius PM generator12 slot, 8 IPM poles, V shaped

PM Generator rotor for 2004 Prius

PM Generator for 2010 Prius


Model (reverse engineer) 2010 TOYOTA PRIUS traction motor

1-Using Infolytica’s powerful electric motor template based Field Solver known asMOTORSOLVE, we can load the program, select motor type-Brushless DC motor,answer no to sizing question.

2-Select General Settings & fill out the input parameters taken from the data provided by ORNL on slides 23, 24 & 25.

3-Select Stator and fill in the required inputs also from the ORNL slide data

4-Then select Rotor and fill in the required inputs from the ORNL slides

5-Select Stator Windings and fill in the phase winding data from the ORNL slides

6-Select Materials and select both the electrical steel and the magnet grade from the list provided.

7-Solve for various performance Results, compare with ORNL test data & learn how to design these types of IPM PM-AC synchronous machines.


The input results, right side under General Settings, left side

Note: the cross section will not look like the one shownuntil after all rotor and stator inputs are complete

Input values fromORNL data


No rotor template is available that allows the creation of extra holes inside used for mass reduction and cooling. This can be createdusing CAD & imported as a .dxf file

Rotor IPM With variable orientation

Rotor IPM DXF imported

The open circuit air gap flux density can be compared


Stator inputs

Select:Stator (round) Input values from

ORNL data


Select:Rotor (with

variableorientation)


Setting the IPM rotor parameters

A long & careful study of web thickness, magnet width & orientationangle required to optimize the reluctance torque & magnet torque.


Typical total torque output of an IPM machineequals reluctance torque plus magnet torque

Peak torque @ angle = 36 deg.

PM torque function of magnet grade, Perm. Coef. & magnet areaReluctance torque function of salient pole width & Inductance ratio


Varying the web between magnetic poles from 1 to 8 mm

Critical design task for IPM design

Web thickness effects the saliency Lq& Ld ratio

Balance the magnet torque and the reluctance torque

Requires many tedious trial magnetic field solutions

As web gets larger, the magnet “V” angle increases.

There are many variations possible, such as multiple magnet layers &flux barriers.


D & Q axis torque plots of 2010 Prius motor

dq

Saliencywidth

I

6 deg. Madvance

30 deg. E optimum gamma angle for

max torque



Select:Stator (round)

Phase Winding layout

Note: This is a single layer winding (one coil side per slot).


Winding slot position list

Phase Windings are Selected based upon highest Winding Factor


Material selection, for shaft, magnets, stator core, rotor core & conductors

Select material choicesfrom those included in data bases or add new materials.

Select:Materials


Simulated back EMF (O.C.) @ 7200 rpm

The back emf can be simulated at any RPM setting.

This example is at 7200 RPM, the speed where the back EMF equals 650 VDC peak, or the same voltage as the DC rail voltage.

Without field weakening


Simulated back EMF (O.C.) @ 13,500 rpm

With no field weakening the back emf is about 1300VDC peak at 13,500 rpm. This means that Toyota used field weakening which can be modeled using a current advance angle.


Cogging torque simulation @ 100 rpm

Select:Cogging torque

Number of data point settings

Accuracy settingsIncrease from 1 default to 3


Open Circuit flux distribution

Note: High leakage flux in bridges & posts required for magnet retention


Simulated back EMF (O.C.) @ 1000 rpm

Select :Back EMF

From choice of phase& line Select:

Line, Phase

Slightly less than 100 V peak at 1Krpm


O.C. back emf with one stator slot skew (1000 rpm)

Under stator design, set skew to 7.5 (Deg.) and solve for Back EMF

Note: Slight skew (rotor or stator) shapes the line to line back EMF closer to a true sine wave reducing harmonics


Air gap flux plot with standard TOYOTA IPM rotor

Peak air gap flux ~ 0.8 TResult of leakage flux from IPM post & bridge


Post & bridge values set to zero to prevent leakage form magnet to magnet in rotor

O.C. flux plot with zero magnet to magnet leakage inside rotor


O.C. Back Emf plot with zero magnet to magnet leakage

At 1000 rpm & zero internal rotor leakage the peak back EMF has increased from 100 V to about 145 V


Peak air gap flux ~ 1.0 TWith zero leakage from IPM post & bridge.

This leakage represents 20% loss in flux linkage

O.C. air-gap flux plot with zero magnet to magnet leakage


Setup for simulation of torque including magnet & reluctance components

Select:PWM analysis

Select: Torque, Magnet & ReluctanceSet angles: 0, 90, 5


Torque vs Speed plots, 650 VDC, 0 advance and 45 deg. advance angles

Select:Torque vs. speed

Input:Advance angle 0, 45Speed, 100, 13500, 100

Note: generating region


Input:Advance angle 0, 45Speed, 100, 13500,

100Current reduced 25%

Torque vs Speed plots, 650 VDC, 0 advance and 35 deg. advance angles

Note: generating region


Torque vs RPM plots, 0 to 45 deg. Advance (650 VDC bus)

Note: With zero advance, 7200 rpm is max. speed attainable with 650 VDC.


2010 Toyota Prius 8 pole, 48 slot IPM machine

Thermal analysis byAdrian Perregaux


3D model for thermal analysis


Hendershot 2015 Copyright Adrian Perregaux

Output torque vs current (Toyota 2010 Prius)


2010 Toyota Prius cooling analysis by internal oil spray cooling



Peak flux distribution of Prius 2010 motor45 deg. advance1.92 T in teeth200 Nm150 A



Open circuit flux distribution of Prius 2010 motor



Temperature rise of key components @ 70% duty cycle



Simulated vs. measured temperature rise Deg. C vs. seconds



Efficiency Plot of 2010 Toyota Prius motor (Motorsolve)

Linearized efficiency plot for fast solution time

Select Efficiency and set up with parameters on right


Efficiency Plot of 2010 Toyota Prius motor (ORNL)


Efficiency Plot of 2010 Toyota Prius motor (Motorsolve)

Linearized efficiency plot (Takes about one hr. to solve)


ISBN 0-19-859389-9 ISBN 978-0-9840687-0-8RED BOOK GREEN BOOK

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