Efficient Motor Control and Power Conversion System

Team MotorBoard

Preliminary Design Review29 January 2009

Nicholas Barr, Daniel Fargano, Kyle Simmons, Marshall Worth

Project SummaryDesign and prototype

an efficient motor control and power conversion system to interface between a 200VDC source and an AC induction motor for both driving and generating power stages

Project PurposeComply with IEEE Future Energy

Competition requirements 1 kW motor 3000 RPM cruising speed 200 Volts DC source 75% efficiency as a motor (3000 RPM) 75% efficiency as a generator (3000 RPM) Locked rotor torque of 30 N-m, for duration of 3 to 5

seconds Initial load of 30 N-m and reach the speed of 3000 rpm

within 3 to 5 seconds Quickly and safely become an alternator

Project PurposeProduce a viable option for industry

Quick and efficient interface for generating and driving

Possible application in hybrid vehicle motor drives

Cheap and easy way to get a 3-phase, high power pure sign wave

IEEE/APEC Dan and Kyle will be

going to Washington D.C. Feb. 13th – 17th

Presenting IFEC progress report to IEEE

Attending Applied Power Electronics Conference

Power Converters Motor Drive Efficiency

Motor3 HP, 3600 RPM

general purpose motor

Baldor 84% efficient at

3600 rpm

System Diagram

Control System

Control SystemLPC-P2148 Olimex devo boardNXP LPC2148FBD64-S

Program Memory Size: 512KB RAM Size: 40KB Package / Case: 64-LQFP Speed: 60MHz Core Processor: ARM7 Data Converters: A/D 14; D/A 1 Core Size: 16/32-Bit Interface: I²C, SPI, SSP, UART, USB

Sensors3 Hall-effect current

sensors for a,b,c line detection

Quadrature encoder (fancy shaft encoder)Most likely opticalPrefer absolute position

sensorDC line voltage sensorOptional (safety):

Temperature sensor

Control Algorithm The objective of the controls algorithm is to sense a set of

inputs from the motor and control board and produce a corresponding 3-phase output voltage.

First we sample the current in phase A,B and C as well as the position and speed of the rotor shaft

Second we determine the motor operating mode, motoring or generating, and the desired speed of operation.

From these quantities the desired DC-DC converter output voltage and phase A,B and C voltages are calculated.

Finally the controller will determine the appropriate duty cycle to emit on the IGBT gate driver input in order to produce the desired voltage at both the output of the DC-DC converter as well as the phase A,B and C voltages produced by the inverter.

Power System195VDC line to

supply from Veriac Large DC supply line

capacitorInput from control

Bidirectional Buck-Boost ConverterInput from control

Bidirectional DC 3-phase AC inverter

Power System

Simulated 3 Phase Waveforms

Test Methodology – Converter Specifications:

95%+ efficiency DC input to Bucked/Boosted DC output

  Test:

At specific duty cycle and input voltage -> Measure and Compare Output voltage to theoretical output voltage determined by the conversion ratio M(D)= -D/(1-D)

Swing the input voltage at specific duty cycle to confirm it works for various voltages

Change the duty cycle and repeat the voltage swing to ensure the converter works at all duty cycles and voltages

If either of the test specifications is not met the inverter must be checked against the schematic design of converter to ensure all components are properly placed and have solid connections.

Test Methodology – Inverter Specifications:

95%+ efficiency DC input -> 3 phase AC output

  Test:

Swing input voltage and monitor output. Peak AC voltage should be no less than 75% of the DC value

At each voltage level, check for clean sinusoidal AC signal and that all 3 phases are 120 degrees apart

If either of the test specifications is not met the inverter must be checked against the schematic design of the inverter to ensure all components are properly placed and have solid connections.

Test Methodology – Controls Specifications:

Control the gates of both the converter and inverter  Test:

Use a logic analyzer to make sure we are getting the correct signals on the output terminals

We will connect the controls to the inverter and converter to see if it will actually control the gates of the transistors

If the controls are not working, use the logic analyzer to check the entire board to make sure all signals are producing correct signals and check it against the schematic to ensure the accuracy of the controls.

MarketabilitySociety is going green energy conservationMakes for more efficient use of the powerPerfect addition to hybrid vehicles

Many companies are focusing on hybrid-electric drive systems but are lacking bi-directionally, specifically the generation of power

This could serve as a quick fix or serve as a prototype for future drive systems

Environmental Impact &Impact on SocietyShift in attitudes is moving

interest towards electric vehicles

Increasing ease and efficiency of battery to motor interface might allow quicker to-market designs

Manufacturing of board can be done in a manner which reduces impact on environment (RoHS)

Sustainability Many of the parts we will be using in our project

are accessible through multiple vendors at low cost. There are no specialty components that would limit us or this project to purchase from any specific vendor.

Motor designed for is very common Electric motors will always be used, independent

of their use in vehicles The most likely component to fail would be the

IGBTs on the inverter which could blow if we don’t account for current spikes in the switching.

Manufacturability Will need to meet FCC/RoHS standards Easy to debug due to breakout pins The tolerances on the components shouldn’t be

that big of an issue for this project. We are aiming to have an efficiency of at least 75% which will rely heavily on our designs of the power electronics and the motor itself but for individual components the tolerances of typical resistors, capacitors, inductors, etc should be adequate for our needs.

Costs of ManufacturingShould be relatively cheap and

marketable/profitable$50 for controls$40 for power components$20-$30 for sensors/power/etc

SafetyPotentially dangerous due to high

current/voltageNo user access to switchingDesign for shock resistanceProper groundingHigh voltage isolation from low voltage

controls

Division of Labor

Project Milestones CDR- part selection/bought, system schematics,

basic power system and basic microcontroller functionality

Milestone I - all hardware working on protoboard, sensors configured and working, and final revision of PCB completed and sent out

Milestone II – working prototype, PCB built and populated

EXPO – final debug, packaging, documentation done

Schedule Overview Buck-Boost Converter: Jan 19-Feb 19 DC:AC Inverter: Jan 19-Feb 19 PCB layout: Feb 20 – March 11 Software: Feb 20 – April 6 Project Completion: April 16

Money Primary Funding:

Fall 2008 EEF mini-proposal applied for and received ($2k) 

Spring 2009 UROP Funding ($1k) Secondary Funding:

Prize money from the IFEC 2007 competition(~$3k)

This money needs to cover the motor design team as well Department funding from Lightner ($5k)

Backup Funding: Professor Barnes has a large grant for student

research projects ($10k+)

BudgetItem Quantity Total Cost

PCB Fabrication 2 $150

Microprocessor 1 $15

Controls parts 2 $60

IGBTs 15 $375

Drivers 4 $30

Power Electronics parts

? $20

Sensors 4 $50

Packaging 1 $100

Printing/Poster/etc 1 $75

Shipping $90

Total $965

Risks and Contingency PlanLack of proper efficiency

Focus on driving side, less emphasis on generating

Hand wired motorCurrent spikes

Designed to have peak current double what we expect

Most parts interchangeable with higher rated components

PCB fabrication problemsWe can wire wrap or use devo board

Questions?