4. TEST SPECIFICATIONSThe figure below illustrates the basic design of our project. The inverter is softwarebased while the battery packs and motor are hardware components. Testing isimportant since the system will be handling large currents around 200 – 250 amps andlarge voltages around 400 – 460 volts. Figure 4.1 Design Concept4.1.Test Certification – SimulationWe will perform simulations to evaluate the brushless DC permanent magnet machinewith respect to the AC induction machine both in motoring and regenerative mode.This will be done using PSAT simulation software, from which we will generate data,e.g. efficiency maps and relative energy consumption. The AC induction and the DCpermanent magnet motor will be evaluated over the same driving cycles. The twomotors will be the same size and will also be run within the same drive train.We will also conduct simulations using MagneForce GenAC / BlDC software that willevaluate the scaling characteristics of permanent magnet brushless motors as afunction of physical size. Performance results will be compared against numbersgenerated by PSAT.4.1.1. PSAT simulationsIn order to evaluate the relative performances of AC induction and brushless DCpermanent magnet motors in a vehicle, PSAT simulations will be conducted overseveral courses and the post- run summaries will be compared to see how efficientlyeach motor operated in a given cycle. Performance tests should then be run to seehow the motors compared with respect to vehicle acceleration and the ability tosustain speeds up hills.Drive-trainMotorInverterBattery RechargeThe simulations are to be performed on a 2x2 hybrid vehicle with manual shifting.This vehicle will retain the default setup with the following modifications: a “normal”SUV model used for the frame, a 75kW compression ignition model used for theengine, NiMH batteries, and a “normal” driver model. Two of the motors to becompared are an 85kW permanent magnet motor from Unique Mobility and theMarathon 75kW AC induction motor. The other two are 59kW induction and 58kWpermanent magnet motors whose characteristics were taken from the paper, "Energy-Efficiency Evaluation of Traction Drives for Electric Vehicles", Proceedings 15thElectric Vehicle Symposium, Brussels 1998, by Marcus Menne, et al..The various configurations will be driven over five cycles: urban, road, highway,japan1015, and epa_combined. The first three vary as one would expect, urban drivinginvolving frequent stops, highway driving involving very few, and generic roads fallingin between. The japan1015 course involves constant acceleration and deceleration ona regular pattern while the epa_combined course causes the vehicle to speed up andstop quickly and erratically. None of the courses involve hills. After all of thesecourses, two more tests will be performed: a gradeability test at 25 m/s and anacceleration test.4.1.2. Motor ModelsFigures 4.1.1 through 4.1.8 below show the efficiency maps of the motor models to beused in the PSAT simulations. The maps were obtained by graphing the desired motordata in PSAT and exporting the images.As the figures show, the permanent magnet motors have consistently wider ranges ofefficient operation. However, the performance of the motors in the same power classshould vary since the torque / speed characteristics differ. One would expect thepermanent magnet motors to be generally more efficient, though, given the smallregions of inefficiency.Figure 4.1.1 – Torque vs. Speed for the 59kW induction motor Figure 4.1.2 – Torque vs. Speed for the 58kW permanent magnet motorFigure 4.1.3 – Power vs. Speed for the 59kW induction motorFigure 4.1.4 – Power vs. Speed for the 58kW permanent magnet motorFigure 4.1.5 – Torque vs. Speed for the 75kW induction motorFigure 4.1.6 – Torque vs. Speed for the 85kW permanent magnet motorFigure 4.1.7 – Power vs. Speed for the 75kW induction motorFigure 4.1.8 – Power vs. Speed for the 85kW permanent magnet motor4.1.3. Magneforce SimulationsTo determine the scaling characteristics of DC permanent magnet motors, a basemotor will be simulated with BLDC to match the following criteria as closely aspossible: max rpm of 2700, max torque of 40 Nm. Data on this motor will then becollected and physical dimensions scaled by factors of ¼, ½, 2, and 4. The data forthese variations will then be collected and the designs ported to GenAC forgeneration- mode data collection.The physical characteristics of the base motor are listed Tables 1 through 3. For eachvariation on the base motor, all physical characteristics are scaled uniformly. Thecharacteristics in the tables were determined through trial and error with the BLDCsoftware.Table 4.1.9: Stator characteristicsFeature Size / Type UnitsMotor length 150 mmStator material M19- 0.50 mmTotal stator weight 7.31 kgOuter diameter 165.5 mmInner diameter 120 mmNumber of slots 18 intTooth width 10 mmYoke width 5 mmSlot opening 2.5 mmTip thickness 1.5 mmFoot thickness 1.5 mmTip radius 0.5 mmTable 4.1.10: Rotor characteristicsFeature Size / Type UnitsNumber of poles 6Magnet type and fieldorientation TDK- fb9b ParallelTotal magnet volume 1.97E+05 mm^3Rotor material M19- 0.50 mmTotal rotor weight 10.74 kgType 610 intOuter diameter 118 mmInner diameter 22.32 mmNumber of poles 6 intMagnet arc 55 degMagnet thickness 4 mmTable 4.1.11: Winding characteristicsFeature Size / Type UnitsArmature phases 3Armature Winding pattern StandardArmature winding table: Turns per coil 12Phase A1, 4, 7, 10, 13, 16,1Slot #Phase B3, 6, 9, 12, 15, 18,3Slot #Phase C5, 8, 11, 14, 17, 2,5Slot #Armature winding branches 2Armature wire size 8 x mwgB1- 1.250Max Armature slot fill 1.58Armature winding resistance 0.02 ohmEnd- turn inductance perphase 2.92E- 05 HenryArm winding copper weight 9.08 kg4.2.Test Certification – HardwareThe physical tests will be
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