Induction Motor Emulation

Senior Design Team 1506

Geoffrey Roy, Amber Reinwald, Matthew Geary

Advanced Power Electronics and Electric Drives Lab (APEDL) ECE Department and Center for Clean Energy Engineering

Final Presentation Fall 2014

12/01/2014

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Ø Background – Lenze Ø Project Objective Ø Design Ø Current Project State Ø Project Simulation and Results Ø Upcoming Tasks Ø DC Motor Ø Budget Ø  Timeline

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Outline

•  Manufacturer of Variable Frequency Drives (VFD) •  VFDs provide motor control to:

•  Robotics •  Manufacturing/packaging •  Automotive construction (conveyor systems)

•  Lenze VFDs also provide speed control for AC motors

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Lenze

Current Problem •  Numerous induction motor and dynamometer pairs •  Test configuration takes up a large amount of space •  Motors give off a significant amount of heat •  Rotating motor degrades over time

Objective •  Develop a variable induction motor emulator that

can: q  Operate under normal motor conditions q  Output loads of 0.5, 1.0, 2.0 hp q  Small in size and has little to no moving parts q  Can be run with a graphical user interface (GUI)

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Objective

Method   Pros   Cons  

PHIL   •  Electrical  machines  can  be  simulated  in  real  9me  

•  No  need  for  moving  parts  •  Allows  more  flexibility  in  prototyping  tes9ng  •  Can  explore  real  power  system  issues  such  

as  stability,  impact  of  ac9ve  power  quality  controls,  and  harmonics  

•  Introduces  inaccuracy  from  sampling  rate,  delay,  quan9za9on,  and  satura9on  

•  Not  a  proven  catch-­‐all  method  to  begin  design  

•  Difficult  to  account  for  all  environmental  variables  

•  Required  device  for  emula9on  is  well  outside  our  budget  

FPGA   •  Millions  of  logic  gates  •  Use  of  hardware  binary  arithme9c  

•  Adders  and  mul9pliers  •  High  precision  •  High-­‐speed  characteris9cs  •  Parallelism  •  Flexibility  to  change/reprogram  

•  Advanced  coding  in  unknown  languages  •  Depends  on  an  accurate  modeling  of  

system  •  High  chance  of  bugging  •  Minor  mistakes  maRer  

•  Requires  more  hardware  •  Draws  a  lot  of  power    

Three design choices for motor emulator: Three-Phase Transformer, Power Hardware in the Loop (PHIL), and Field-Programmable Gate Array

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Researched and Proposed Solution

Pros: •  Per-phase equivalent circuit model of a transformer and induction motor are

fundamentally equal •  Magnetic fields are coupled •  No moving parts •  Cheapest option Cons: •  There is no internal slip dependency •  Not the smallest option

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Emulation Choice: Three-Phase Transformer

High Power Rheostat •  No programming needed •  Can be manually adjusted •  Small Caveat: •  Small moving parts •  Requires DC motor to adjust using GUI •  Requires three to emulate a three-phase load

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Implementing Slip Dependency

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Initial Prototype Design

1.   2.  

3.  

4.  5.  

6.  

1.  VFD drives transformer with varying frequency and voltage

2.  When driven the transformer will have a transient response like a motor

3.  With the GUI a user will set the output power and either set a specific or varying slip value for the transient response

4.  Motor drive IC will drive the DC motor 5.  DC motor turns the delta connected rheostats 6.  Rheostat values are Rr*(1-s)/s; where s = motor slip

Slip:  single  input  or  varying?  Output  Power:  0.5,  1.0,  2.0  hp?  

•  Induction motor parameters calculated from motor characterization tests §  Finalizing Induction motor and three-phase

transformer simulation based off calculated parameters o  Simulation steady state output values need to be

the same

Ø  Following simulation completion we will purchase parts

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Current State of Project

A motor characterization test was conducted to obtain our equivalent motor parameters. •  DC Test

•  Determines stator resistance (R1) •  No-Load Test

•  Rotor speed is very close to synchronous speed (R2*(1-s)/s = 0) •  Determines magnetizing reactance (Xm) •  Determines core resistance (RFe)

•  Locked-Rotor Test •  Motor’s rotor was held so it would not turn •  Determines rotor resistance (R2) •  Determines stator and rotor reactance (X1 and X2)

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Motor Calculations

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Induction Motor Simulation

Rs = 138.808 Ω Rr = 137.256 Ω Rc = 2.6064 kΩ Ls = 0.2968 H Lr = 0.4452 H Lm = 5.355 H T = 0.38 and 0.2 J = 0.003 Poles = 4

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Results

Rotor and Stator Currents

Motor Rotations Per Minute

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Results

Motor Output Power

Motor Torque

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Three-Phase Transformer Simulation

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Simulation Problems

Varying Load Resistance •  We need to vary slip from 0 à 1 in a single simulation

Power Output •  We would like to see the same power output as the

induction motor simulation

•  Assemble our motor emulator §  Connect transformer to our rheostat load

•  Test our emulator §  Drive the transformer with Lenze VFD and compare our

results with Lenze motor under the same conditions •  Decide which DC motor to purchase •  Ensure DC motor rotates rheostats as intended •  Design a PCB for the DC motor driver •  Interface the motor driver with a GUI that a user can

adjust the slip and output power with

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Upcoming Tasks

•  Need to precisely move the dial on the rheostats to properly emulate rotor slip

•  Forward and reverse motion is necessary •  Stepper motor

q Motion in steps with precision of so many steps per revolution

q DC motor involves speed control; precise movements are hard to achieve

q Around $20 or less

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Rheostat Motion

•  Stepper motor driver kits are available, though not ideal for use

•  Arduino Mega 2560 (~$45) q Arduino boards are able to interface with Python

•  Intend to design our own PCB Motor Driver using a driving chip as a base q Possible chip: A3967 microstepping driver

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Driving the Motor

Preliminary Budget ~ $3000

Item costs: •  Three-phase transformer ~ $1000 •  (3x) High power rheostat ~ $500 (x3) Remaining Budget ~ $500

Future Purchases •  Motor chopper PCB layout/fabrication •  Possible motor driving IC (Arduino) •  DC motor

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Budget

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Timeline

Sept.   Dec.  Oct.   Nov.   Feb.  Jan.   Mar.   Apr.  

May  

Induc9on  Motor  &  Motor  Emula9on  Research  

Three-­‐Phase  Transformer  as  a  Motor  Emulator  Research.  Parts  Research/Purchasing  

Induc9on  Motor  Emula9on  &  Simula9on.    

DC  Motor  Research.  Design  and  Purchase  Motor  Driving  IC/  Motor  Chopper  PCB  

Emulator  Assembly  &  Tes9ng.    

Emulator  Op9miza9on  or  Fixing  if  needed  

GUI  Design  &  Tes9ng.  Interfacing  GUI  with  DC  Motor  and  Emulator  

Total  System  Integra9on  &  Tes9ng.  This  Would  Include  Op9miza9on  and  Fixing  If  Needed  

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Questions?

Citations

•  [1] Knight. “Electrical Machines”. EE 332 – Electrical Drives [Online]. Available: http://people.ucalgary.ca/~aknigh/electrical_machines/machines_main.html. [Accessed: October, 2014]

•  [2] Lenze AC Tech Corporation. “StockMotors AC motors 90W to 315kW three phase squirrel cage induction motors,” Catalog: MDERA0601.

•  [3] Lenze AC Tech Corporation. “SMVector – Frequency Inverter Operating Instructions,” Document: SV01N_13418587

•  [4] O. Vadyakho et al., "An Induction Machine Emulator for High-Power Applications Utilizing Advanced Simulation Tools With Graphical User Interfaces," Energy Conversion, IEEE Transactions on, vol.27, no.1, pp.160, 172, March 2012

•  [5] http://www.o-digital.com/uploads/2179/2188-1/DC_Motor_Z2D15_24_507.jpg •  [6] http://320volt.com/en/ta8435-ile-bipolar-step-motor-surucu-devresi/ •  [7] http://www.directindustry.com/prod/getra/three-phase-transformers-25208-799759.html •  [8] http://www.directindustry.com/prod/mf-power-resistor-ltd/power-

rheostats-39029-295332.html#product-item_1501619 •  [9] http://www.dspace.de/shared/img/company/press/pressefotos/originals/MidSize-

Simulator_RGB.jpg

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