Motor Control

© 2008 Microchip Technology Incorporated. All Rights Reserved. Class Title Slide 1

1253 IMC

Overview of Intelligent Motor Control Solutions

© 2008 Microchip Technology Incorporated. All Rights Reserved. 1253 IMC Slide 2

Class Objectives

When you finish this class you will know:

What electric motors are, and how they operateHow to select the best motor for your application based on the characteristics, and features of the most common electric motor types How to control these electric motors, and the resources available to assist you


AgendaBasic Motor TheoryOverview of common motor types and applications

DC Brush MotorDC Brushless MotorPermanent Magnet Synchronous MotorAC InductionStepper MotorSwitched Reluctance Motor

Motor control algorithms and resources


Basic Motor Theory


Basic Motor Theory

What is a Motor?A Motor Converts Electrical Energy to MechanicalA Motor Converts Electrical Energy to Mechanical

Force is developed when charge moves through a Force is developed when charge moves through a magnetic fieldmagnetic field

How?How?

F = I x BF = I x B


Left Hand Rule

I

B

F

I

B

F = I x B

N

S

F


Motor Torque

Torque production

Taking direction of F into account T=Fr sin θ


Motor Torque

SummaryTorque = Force * Distance

F = I x BT = ( I x B ) * DWhen B and D are constant T = K * I A

When field is wound B = K * I F

In wound DC motors Torque and Flux B can be controlled independently


Motor Torque

B BSN

I

BF

T=F x D

D

F

F


Common Motor Typesand Applications


Motor Classification


Topics of Discussion:

DC Brush MotorDC Brushless MotorPermanent Magnet Synchronous MotorAC Induction MotorStepper MotorSwitched Reluctance Motor


DC Brush MotorOperating Principle:

Rotor/Armature comprised of wire wound conductive laminates Stator has permanent magnets (or wound field)Commutation is performed through mechanical contact (brushes)Synchronous, internal commutation

Characteristics:Good controllability

On/Off, ProportionalLinear torque/current curveSpeed proportionate to voltage appliedRequires maintenanceLow overloading capabilityLow heat dissipation

PermanentMagnet

Windings

StatorBrushes

Rotor


DC Brush Motor

Application examples:WipersDoor locksWindow liftsAntenna retractorSeat adjustAnti-lock Braking SystemCordless hand drillElectric lawnmower

BrushesPermanentMagnet

Stator CommutatorWindings

Laminate Core


DC Brushless MotorOperating Principle:

Rotor comprised of permanent magnetsStator has windingsCommutation is performed electronically Operates as an ‘inside-out’ DC motor

Characteristics:No sparks -> safer in explosive environmentsCleaner, faster, more efficientLess noisy, more reliableLinear current/torque relationship -> smoother accelerationGood overloading capability

Rotor

StatorPermanent

Magnet

Windings


DC Brushless Motor

Application examples:Anti-lock Braking SystemDisk Drive ServoThrottle controlFuel pumpOil pump

Hall sensors

Stator winding

Rotor magnets

Bearings


Brushed & Brushless DC Motor Construction

PERMANENT MAGNET BRUSHED DC MOTOR

PERMANENT MAGNET BRUSHLESSDC MOTORPermanent

MagnetPermanent

Magnet

Windings

Stator Brushes

Rotor RotorWindings

Stator


BLDC vs. BDC Motor

Moderate - Due to increases in steel & copper. ( with wound field stator)

Moderate - Since it has permanent magnets, building cost may be higher. However, steel & copper prices are up

Cost of Building

Arcs in the brushes will generate noise causing EMI in the equipment nearby

Low, because it has permanent magnets on the rotor. This improves the dynamic response.

Electric Noise Generation

Lower - Mechanical limitations be the brushesHigher - No mechanical limitation imposed by brushes/commutator

Speed Range

Higher rotor inertia which limits the dynamic characteristics

Low, because it has permanent magnets on the rotor. This improves the dynamic response.

Rotor Inertia

Moderate/Low - The heat produced by the armature is dissipated in the air gap, thus increasing the temperature in the air gap and limiting specs on the output power/frame size

High - Reduced size due to superior thermal characteristics. Because BLDC has the windings on the stator, which is connected to the case, the heat dissipation is better

Output Power/ Frame Size

ModerateHigh - No voltage drop across brushesEfficiency

Moderately flat - At higher speeds, brush friction increases, thus reducing useful torque

Flat - Enables operation on all speeds with rated load

Speed/Torque Characteristics

ShorterLongerLife

Periodic maintenance is requiredLess required due to absence of brushesMaintenance

Brushed commutationElectronic commutation based on Hall position sensors

Commutation

Brushed DC MotorBLDC MotorFeature


Permanent Magnet Synchronous Motor

Operating Principle:Rotor comprised of permanent magnetsStator has windingsCommutation is performed electronically Sinusoidal Back EMF

Characteristics:No sparks -> safer in explosive environmentsCleaner, faster, more efficientLess noisy, more reliableHigh Efficiency & ReliabilityDesigned for high-performance Servo ApplicationsRuns with/without Position EncodersMore compact, efficient and lighter than ACIMCoupled with FOC control produces optimal torqueSmooth low and high speed performanceLow Audible Noise & EMI

Rotor

StatorPermanent

Magnet

Windings


PMSM ApplicationsAir Conditioner & Refrigerator (AC) compressorsDirect-drive washing machinesAutomotive Electrical power steeringMachining ToolsTraction controlData Storage

Hall sensors

Stator windingsRotor

Permanentmagnets


PMSM Construction PMSM is an AC synchronous motor whose field excitation is provided by PMsSimilar to the BLDC but BEMF is sinusoidal The Back EMF ideally contains no harmonicsLeads to a reduction in audible noise Better efficiency


AC Induction MotorOperating Principle:

Reverse of an alternator (generator)Rotor and stator carry alternating currentConstructed in either 1- to 3- phase Asynchronous motor

Characteristics:Low Cost to manufactureSimple, low-cost design for fixed-speed applicationsLower efficiency than other motor typesSpeed proportionate to line frequency (50 or 60 Hz)Complex control for variable speed and torque

120 * frequency120 * frequencyPolesPoles

Synchronous = Synchronous = SpeedSpeed


ACIM ApplicationsLarger horsepower motorsAir Conditioner & Refrigerator compressorsWhite good machinesPumpsBlowersAutomationPower Tools

AC Induction motor 90%

Other motors

Bearings

Stator windings

Squirrel Cage Rotor


BLDC vs. AC Motor

The rotor runs at a lower frequency than the stator by slip frequency and slip increases with the load on the motor

No slip is experienced between stator and rotor frequencies

Slip

No Controller is required for fixed speed; a controller is required for variable speed

A controller is always required to keep the motor running. The same controller can be used for variable speed control

Control Requirements

Approximately up to seven times rated - Starter circuit rating should be carefully selected. Normally uses a Star-Delta starter

Rated - No special starter circuit requiredStarting Current

High - Poor dynamic characteristicsLow - Better dynamic characteristicsRotor Inertia

Moderate - Since both stator and rotor have windings, the output power to size is lower than BLDC

High - Since it has permanent magnets on the rotor, smaller size can be achieved for a given output power.

Output Power/ Frame Size

Nonlinear - Lower torque at lower speedsFlat - Enables operation at all speeds with rated load

Speed/Torque Characteristics

AC Induction MotorsBLDC/PMSM MotorsFeatures


Stepper Motor

Operating Principle:Rotor consists of permanent magnets with many polesStator has two pairs of windings.

Characteristics:Easy to position – moves in steps based on pulses supplied to the stator windingsDirection of rotation is changed by reversing the pulse sequenceSpeed control is by the frequency of pulses or pulse rate

Rotor

StatorPermanentMagnets

N/S Poles

Windings


Stepper MotorApplication examples:

Idle speed adjustExhaust gas re-circulationDuct airflow vanesMirror controlTelescopesAntennasToysMany others!

BearingsStator windings

Rotor magnets


Switched Reluctance MotorOperating Principle:

No permanent magnetsRotor consists of iron laminatesStator similar to brushless DC motorTorque produced as a result of attraction between electromagnet and iron rotor

Characteristics:Motor construction is simple and cheapNeeds MCU control to reduce torque ripple and audible noise

Rotor

Stator

Windings


Switched Reluctance MotorApplication examples:

Fuel pumpThrottle controlOil pumpABSVacuum cleanerLawnmowerWashing machineAutomatic Doors in buildings and vehiclesFans

Rotor

Stator

Windings


1253 IMC

Motor Drives


Motor Drives

Direct on line starter – Relay DriveThyristor driveMotor Soft StarterElectronic speed control

Adjustable-speed driveVariable-frequency driveTorque and speed control


Variable Speed/Frequency Drives


Need for Variable Speed Drives (VSD)

Electric motors consume 1/3 power in USMotorized Equipment oversized

Exceed maximum torque requirementsMotors oversized

To meet equipment requirementsMotor usually in continuous, full-speed operation


Variable motor frequency – Energy efficientMany applications (fan, pumps) follow affinity law20% reduction in speed ~ 50% reduction in power

Better performanceApplication specific V/f curvesTorque and slip controlNoise control

Increased motor life spanReduced starting currentProtection against supply disturbances

Other benefitsReduced Volume and Weight ie: Lower PriceFault detection and displayNetworked solutionStandards compatible product

Electrical Motor Drive –Advantages


Motor and Drive Application Requirement

Constant TorqueMixers, screw feeders, extruders and positive displacement pumps

Constant Power High torque is required at low speedLow torque at high speedMachine tools, tractions

Variable Torque Low torque is required at a low speedHigher torque at high speedCentrifugal loads such as fans, pumps and blowersMost energy savings from variable frequency drive


Control Technique TypesVector/Field Oriented Control

Indirect control variables are Flux and TorqueScalar Control (V/F control)

Voltage AmplitudeSine PWMSVM PWMSix Step PWM

Rotational FrequencyDirect Torque Control

Direct control variables are Flux and Torque


Motor

115/230VAC50/60Hz

Rectifier

PIC®

Microcontroller3-Phase Bridge Driver

SMPSMOSFET Driver

IREIF

Active PFC

Computer

Display and

Control Panel

Feedback Devices

VSI

Electrical Motor Drive – Block Diagram


Electrical Motor DriveInput – Output


Electrical Motor DriveInput – Output


1253 IMC

Motor Control Algorithms


Brush DC Motor


DC MotorRed is North PolarizationBlue is South PolarizationOpposite Polarities attract Rotor will rotate until North is aligned with SouthJust before alignment commutator contacts and energizes next windingSpark is generated when the commutator changes windings


Closed Loop Control

PID Motor+ -Desired Speed

Measured Speed

Speed Error Voltage

SpeedCalculation

Hall SensorPeriod


Low Side Drive Configuration for DC Brushed Motor

Desired PIC® MCU or dsPIC® DSC FeaturesCCP, ECCP, MCPWM, SR Latch10 Bit High Speed ADCInternal ComparatorInternal TMRs


High Side Drive Configuration for DC Brushed Motor

Desired PIC® MCU or dsPIC® DSC FeaturesCCP, ECCP, MCPWM, SR Latch10 Bit High Speed ADCInternal ComparatorInternal TMRs


H-Bridge Configuration for DC Brushed Motor

Desired PIC® MCU or dsPIC® DSC FeaturesECCP, MCPWM10 Bit High Speed ADCInternal ComparatorChange NotificationQuaduature Encoder Internal TMRs


Brushed DC Motor Design Flow Chart

VariableSpeedMotor?

Unidirectionalor Bi-directional

Control?

Open Loop orClosed Loop

Control?

SpeedControl?

PositionControl?

Any PIC MCU

No, On/OffControl Only

1 I/O Pin

Yes

No

1 H/W PWM orFirmware (plus 1-4 I/O Pins)

Bi-directional

Closed Loop Control

Open Loop

TachometerADC Input or

Interrupt

1 Shunt Resistor withOpAmp Circuits,or 1 Hall EffectTransducers1 ADC

Yes, FaultShut Down

OnlyTorqueControl?

No

Yes

QuadratureEncoder

Unidirectional

1 H/W PWM orFirmware

MCU orDiscreteSolution?Yes

Yes YesPotentiometerADC Input

QEI Module

ExternalLogic


Brushed DC Application Resources

The DC Motor Control Tips ‘n Tricks document has lots of information about driving brush DC motors.

DS41233

This app note provides C code for a position servomotor application. Two versions of the code are provided for the PIC16F877 device and PIC18C452, respectively. Position information is obtained from the motor using an incremental quadratureencoder and external decoding logic.

PIC18CXXX/PIC16CXXX DC ServomotorAN696

The PIC16F684 has the Enhanced Capture Compare PWM (ECCP) peripheral for driving a H bridge inverter. This makes the device an excellent choice for low-cost control of a brushed DC motor.

Low-cost Bi-directional Brushed DC Motor Control Using PIC16F684AN893

Start here if you would like to learn more about basic brush motor theory.

Brushed DC Motor FundamentalsAN905

Brushed DC


Brushless DC Motor


What is Commutation?Revolving Electrical Field GenerationThis Rotating Field is synchronized to the rotor magnet to generate torqueContinuous Torque generation keeps the motor moving


Six Step for BLDCCommutation – six steps per electrical rev.Phase currents rectangularLess processing power requiredProduces more Torque than PMSMCreates more torque ripple

Rotor position unknown between commutationPosition Information Required

Hall sensors indicate commutation pointBack EMF zero cross for sensorless

Starting ramp tuning for BEMF signal


Six Step BLDC Control

+TORQUE FIRING

BR G

Q1 Q3Q2

Q4 Q6Q5Green Winding

Q1,Q5 Q1,Q6 Q2,Q6 Q2,Q4 Q3,Q4 Q3,Q5

60o

HALL A

HALL B

HALL C

Q1,Q5 Q1,Q6Q3,Q5

Sector 5

Hall State0 1 2

5 4 6 2

3

34

1

55

04

16

Blue Winding

Red Winding


Brushless DC Motor Energization

100

N

S

R

G

r

r

bb

g

gB

com

com

com

110

010

011

101

001

R

GB

N

S


Brushless DC DriveDesired PIC® MCU or

dsPIC® DSC FeaturesMCPWM Fault Shutdown10 Bit High Speed ADCInternal ComparatorChange NotificationQuaduature Encoder Internal TMRs


BLDC Application Resources

In this class we discuss how a 3-phase brushless motor operates, the drive circuitry required to commutate the motor, and methods for determining the motor position before it starts and as it rotates. Emphasis is on controlling the motor with a low cost PIC16Fxxx Mid-range microcontroller. Code development for motor startup, acceleration, and steady state operation is covered as are techniques for reducing torque ripple and regenerative breaking. Exciting live motor demonstrations are performed.

3-Phase Brushless Motor Control With Low Cost PIC16 Microcontrollers1255 TPM

Masters Class

This application note describes a sensorless BLDC application using the BEMF detection method.

Using the PIC18F2431 for Sensorless BLDC Motor Control AN970

This application note provides a basic solution for driving a BLDC motor with 3 hall sensors.

Brushless DC Motor Control Using PIC18FXX31AN899

This application note presents a software solution that can be implemented using a low-cost 8-bit microcontroller. The software provides sensorless motor commutation and open-loop speed control.

Sensorless Brushless DC Motor Control with PIC16AN1175

Low Cost BLDC Control Solutions

This application note provides a good overview of brushless DC motor characteristics and presents software solutions for the PIC16Fxxx family of devices.

Brushless DC Motor Control Made Easy AN857

If you are not familiar with how a brushless DC motor works, this is a good place to start.

Brushless DC Motor FundamentalsAN885

BLDC


Sensorless BLDCEliminate Hall-Effect sensors and cabling cost by going sensorless FIR Filtering of the BEMF and or using Majority Detect can help with high-speed

motors or motors with distorted BEMF signalsADC (or comparators) supports the sampling of the motor phase BEMF voltagesFrom the voltages, the CPU determines the rotor position and drives the motor

control PWM module

Phase R

Phase B

Phase G


BLDC Motor Design Flow Chart

2 Phase or3 PhaseMotor?

Open or ClosedLoop?

Sensored orSensorless

Control?

Analog or DigitalFeedback?

Torque Control?

Any PIC MCU orIntegrated Fan Controler

Firmware Commutation2 I/O Pins

3-Phase

No

Comparators,High Speed ADC,

Filters

PWM or Motor Control PWM,ADC Inputs, I/O Pins

Open LoopSpeed Control

Closed LoopControl

Sensored

Sensorless

MeasureBack EMF

3 Shunt Resistors with OpAmp Circuits,or 3 Hall Effect Transducers & ADC

Yes

Yes, FaultShut Down

Only

OpampsComparitors,I/O Interrupts

Analog

Digital

Speed orPositionControl?

6 I/O Pins2-3 ADC Inputs

PWM, Motor Control PWM,

No YesQuadrature Encoder

Timer, Input Capture,or Interrupt


Advanced BLDC Application Resources

This updated workshop class provides a detailed overview of BLDC motor theory and control algorithms. The class also provides anintroduction to the dsPIC30F/33F architecture, and motor control peripherals, along with an in depth look at the newest Microchip’s sensorless BLDC Motor Control application (AN1160) and Motor Control Graphical User Interface.

dsPIC® Digital Signal Controllers (DSC) Motor Control Workshop1256 MCW

Masters Class

This application note describes a sensorless BLDC motor control algorithm, implemented using the dsPIC® Digital Signal Controller (DSC). The algorithm works by the use of a majority function for digitally filtering the back-Electromotive Force (BEMF). Each phase of the motor is filtered to determine when to commutate the motor drive voltages. This control technique excludes the need for discrete, low-pass filtering hardware and off-chip comparators.

Sensorless BLDC Control with Back-EMF Filtering Using a Majority FunctionAN1160

This application note uses the dsPIC to operate a 3-phase BLDC motor without position sensors. The application samples the BEMF signals using the high-speed ADC converter and uses DSP filtering to pre-process the signals. This filtering minimizes external components. This application is optimized for high speed motor operation.

Sensorless BLDC Control With Back-EMF FilteringAN1083

For a version of this same application that is optimized for the 28-pin dsPIC30F2010 device, see AN992. This code would also work well with other 28-pin and 40-pin dsPIC30F motor control device variants.

Sensorless BLDC Code for 28-Pin dsPIC30F DevicesAN992

This application note describes a sensorless BLDC control application using the BEMF detection method. The dsPIC DSC ADC is used to detect the BEMF voltage. The application is written in C language for a dsPIC30F6010 or a dsPIC30F6010A device. The source code has parameters to adjust the open loop startup sequence and also the closed loop operation of the motor. A GUI is available in the MPLAB® IDE to help set the parameters. See GS005 for more information about the GUI.

Using the dsPIC30F for Sensorless BLDC ControlAN901

This application note describes a BLDC application using hall effect sensors for motor position feedback. The application source code is written in C and optimized for the dsPIC30F2010 and other 28-pin dsPIC® DSC variants.

Sensored BLDC Motor Control Using dsPIC30F2010AN957

Advanced BLDC Control Solutions


Permanent Magnet Synchronous Motor


Sine PWM

VSI output is Sine modulated PWMMotor acts as a low pass filter Motor integrates PWM voltage to produce sine currentOutput voltage is proportional to frequency, maintaining constant V/fSpace Vector Modulation allows for 100% line to line modulation


Six Step Sine Control

Sine Phase

Green Winding

60 120 180 240 300 0

60 o

HALL A

HALL B

HALL C

60 1200

Sector 5Hall States

0 1 2

5 4 6 233

41

55

04

16

Blue Winding

Red Winding

R G

Q1 Q3Q2

Q4 Q6Q5B


FOC for PMSMV/F Sinusoidal drive produces smooth control at low speed but is inefficient at high speedsFOC provides smooth control at low speeds as well as efficient control at high speedsFOC provides the best of both worldsField Weakening

What happens when the Back EMF approaches the supply voltage?To enable more speed the rotor field must be weakenedThe stator d axis current is set to a negative valueTorque reduces and speed increases with field weakening


PMSM Operation

S

N

S

N

N

S

N S

θS

N

S

N

N

S

N S

90°

BEMF (V)

Current (I)

BEMF (V)

Current (I)

Without FOC With FOC


PMS Motor Energization

100

N

S

R

G

r

r

bb

g

gB

com

com

com

110

010

011

101

001

120600Sine Phase

Green Winding

60 120 180 240 300 0

Sector5Hall States

0 1 2

54 6 2

3

341

55

04

16

Blue Winding

Red Winding


PMSM CharacteristicsTorque/Current

Speed0

Continuous operation

Short time operation VSI voltage line

Demagnetization limit

VSI current/Torque limit

ωr

T0

ωmax


Permanent Magnet Synchronous Motor Driver

Desired PIC® MCU or dsPIC® DSC FeaturesMCPWM Fault Shutdown10 Bit High Speed ADCInternal ComparatorChange NotificationQuaduature Encoder Internal TMRsHigh Speed Math


FOC Sensorless PMSMTop of the line dynamic torque response and efficiency and the lowest system cost motor control solution ADC supports sampling the motor voltage and currentsDSP supports Clark and Park transformations transform and two PI loops controlling torque and fluxDSP supports speed and position PI loops as determined by an estimator motor model rotor position outputThe outputs of the PI loops are transformed using Space Vector Modulation to drive the MCPWM outputs to

the motor


PMSM Application Resources

New dsPIC® DSC algorithm has been developed for Sensorless Field Oriented Control for Permanent Magnet Synchronous Motor (PMSM). This algorithm takes advantage of the processing power of the DSP engine present on dsPIC33F DSC.

Sensorless FOC for PMSM with dsPIC® Digital Signal Controller (DSC)1258 FOC

Masters Class

Active power factor correction is often used in electronic motor control applications to improve conversion efficiency. This application note describes a software solution that is designed to operate on Microchip’s motor control development system (P/N DM300021).

Power Factor Correction in Power Conversion Applications Using the dsPIC® DSCAN1106

This application is similar to AN1017, but eliminates the need for rotor position feedback sensors. An estimator algorithm calculates the position of the rotor from measured voltages and currents.

Sensorless Field Oriented Control of Permanent Magnet Synchronous MotorsAN1078

This application note uses a 28-pin dsPIC30F device and the PICDEM™ MCLV Development Board to control a PMSM with hall effect sensors. The application also features a speed control loop that allows 4-quadrant torque control.

Sinusoidal Control of PMSM Motors with dsPIC30F DSCAN1017

PMSM


AC Induction Motor


AC Induction Motor

Simple Control for Direct On Line or ThyrisistordriveModerate control for Voltage/Frequency driveField Oriented/Vector Control

Smooth control at low speedsEfficient control at high speedsComplex control for variable speed and torque

Must know rotor position (velocity) for slip and vector controlRotor position sensor is eliminated for sensorless vector control strategiesSensorless control does not work at low motor speeds


Field Weakening

Ψ,U

Speed0Constant

Power Region

Constant Torque Region

ωr ωmax

Ψo

Uo

ACIM Characteristics

Voltage

Torque TmaxTmax

Vrated


AC Induction Motor DriveDesired PIC® MCU or

dsPIC® DSC FeaturesMCPWM Fault Shutdown10 Bit High Speed ADCInternal ComparatorChange NotificationQuaduature Encoder Internal TMRsHigh Speed Math


FOC Sensorless ACIMTop of the line dynamic torque response and efficiency and the lowest system cost motor control solution ADC supports sampling the motor voltage and currentsDSP supports Clark and Park transformations transform and two PI loops controlling torque and fluxDSP supports speed and position PI loops as determined by an estimator motor model rotor position outputThe outputs of the PI loops are transformed using Space Vector Modulation to drive the MCPWM outputs to

the motor


AC Induction Motor Design Flow Chart


ACIM Application Resources

This is an introductory level document to teach the reader about variable speed ACIM control. It also provides simple assembly code example for the dsPIC® DSC that will control a single phase or 3-phase ACIM.

An Introduction to AC Induction Motor Control Using the dsPIC30F MCUAN984

Space Vector Modulation is a special PWM control technique that allows a higher peak voltage to be delivered to the motor from the inverter while producing sinusoidal motor currents. AN955 describes the theory of Space Vector Modulation and presents an assembly code example for the PIC18F architecture.

VF Control of 3-Phase Induction Motor Using Space Vector ModulationAN955

This app note provides a control solution for a 3-phase ACIM using the PIC18Fxx31 series of microcontrollers. These are the preferred devices for ACIM control in the PIC18F family since they have a specialized motor control PWM peripheral that can drive a 3-phase inverter with a minimum amount of external hardware and minimal software overhead.

VF Control of 3-Phase AC Induction Motors Using the PIC18F4431AN900

The PIC16F7x7 series of devices are a good choice for low cost 3-phase ACIM control since they have 3 PWM generators.

VF Control of 3-Phase Induction Motors Using PIC16F7X7 MicrocontrollersAN889

The PIC16F72 provides a low cost solution for variable speed control of a single phase ACIM.

Bi-directional VF Control of Single and 3-Phase Induction Motors Using the PIC16F72AN967

As the name suggests, this app note will teach you the basics of how AC induction motors work.

AC Induction Motor FundamentalsAN887

ACIM


ACIM Application Resources(Continued)

The dsPIC® DSC family of devices offers DSP performance and peripherals that are well matched for advanced motor control algorithms. This class starts with an introduction to the characteristics of the AC induction motor. An overview of electronic control methods is provided from a historical perspective. Finally, the theory and benefits of Sensorless Field Oriented Control (FOC) are explained. A demo of the Sensorless FOC algorithm will be shown in the class. Hands-on exercises will allow you to experiment with the basic and advanced control methods described in this class.

Sensorless FOC for ACIM with dsPIC® Digital Signal Controller (DSC) 1257 ACI

Masters Class

Active power factor correction is often used in electronic motor control applications to improve conversion efficiency. This application note describes a software solution that is designed to operate on Microchip’s motor control development system (P/N DM300021).

Power Factor Correction in Power Conversion Applications Using the dsPIC® DSCAN1106

This application note presents a solution for sensorless Field Oriented Control (FOC) of induction motors using a dsPIC® Digital Signal Controller (DSC). Position and speed of the motor are estimated using software PLL.

Sensorless Field Oriented Control (FOC) of an AC Induction MotorAN1162A

This app note shows a high-performance control solution for an ACIM. Motor current and velocity are sensed and regulated using a closed-loop control system.

Using the dsPIC30F for Vector Control of an AC Induction MotorAN908

ACIM


Motor Control Algorithms

Lower NoiseSensored (Hall Effect) (Sinusoidal/180º)BLDC/PMSM

Highest EfficiencyBest Torque

Control

Sensorless (requires advanced tuning)- FOC with single or dual shunt circuits

PMSM

Lower CostSensorless (requires moderate tuning) (Trapezoidal/120º)- Back EMF with A/D- FIR filtered BEMF with A/D- FIR filtered BEMF with A/D and Majority Detect function

BLDC

Better TorqueControl

Sensored (Hall Effect) (Trapezoidal/120º)- High speed operation (5 to 20K RPM)- Rapid load changes requiring fast torque response- Fast or high accuracy on a servo position response

BLDC

Better ControlClosed Loop- Sensored (QEI)- Sensorless FOC (Vector Control/180º) with

single/dual shunts

3-phase ACIM

Low CostOpen Loop (V/F) with variable speed3-phase ACIM

BenefitsControl TechniqueMotor


* dsPIC30F Application Notes or demo code available

** ACIM Sinewave tables stored in program Flash memory ***Depends on motor speed and A/D sampling speed

MCU Requirements

10K Bytes FLASH 256 Bytes RAM

5 -15***

9Back EMF (ADC)LowMedium-HighSensorless Commutation optional current or speed loops

26Back EMF (with external comparators)

Low-Medium

Medium-HighSensorless Commutation

0.51.5-23-Positions (Input Capture)MediumLowCommutation with Hall Effect Sensors

BLDC Motors

252-Phase Currents (ADC) 3-Phase Voltages (ADC)

MediumMedium-HighSensorless Vector Control

7.25 K Bytes FLASH 244 Bytes SRAM*

9Speed (QEI) 2-Phase Currents (ADC)

HighHighVector Control*

610Speed (QEI) 2-Phase Currents (ADC)

HighMediumSlip Frequency Control

57.5Speed (QEI) Bus Current (ADC)

Low-Medium

Low-MediumSlip Optimization

34.5Speed (QEI)LowLowSlip Limit (V/F)

<2 K Bytes Flash 32 Bytes SRAM**

23NoneLowLowVolts/Frequency*

ACIM Motors

dsPIC DSC resources

dsPIC DSC®MIPS

PIC18 MIPS

Sensing RequirementsRelative Cost

Relative Performance

Algorithm Type


Stepper Motor


Stepping the Motor

Different step modes produce different step angles

Full Step Half Step Microstep


Microstepping

Increases Step ResolutionDivides a Full Step into sub-steps

Smoother transitions between stepsLimits noiseReduces anti-resonance problems

Maximum torqueLow step ratesHigh step rates


Microsteps vs. Step Rate

Increasing microsteps will require an increase in step rate

To produce same RPM as Full Step

Step Rate x 32Full Step/32

Step Rate x 16Full Step/16

Step Rate x 8Full Step/ 8

Step Rate x 4Full Step/ 4

Step Rate Factor for Equivalent Full Step RPM

Number of Microsteps

Number of microsteps can be > 32 Practically stepper performance isn’t improved


Microstep Look-Up Table

100%100%+Sin 90°+115

95.6%100%+Sin 73.1°+11298%100%+Sin 78.75°+113

99.5%100%+Sin 84.35°+114

93%100%+Sin 67.5°+11188%100%+Sin 61.8°+11083%100%+Sin 56.25°+1977%100%+Sin 50.6°+1871%100%+Sin 45°+1763%100%+Sin 39°+1656%100%+Sin 33.75°+1547%100%+Sin 28°+1438%100%+Sin 22.5°+1329%100%+Sin 16.8°+1220%100%+Sin 11.25°+119.8%100%+Sin 5.6°+10

PWM2DC

PWM1 DC

Winding B(current)

Winding A(current)

Microstep

90°/16 Steps= 5.625°/Step

Sin 5.6°= 0.098or

9.8% Duty Cycle


Microstepping SummaryGradual current change from one winding to anotherImplemented using variable DC PWMRequires more processing powerCode utilizes a LUT based on Sine functionSignificantly reduces anti-resonances


Stepper Motor DriverDesired PIC® MCU or

dsPIC® DSC FeaturesCCP, ECCP,MCPWM 10 Bit High Speed ADCInternal ComparatorChange NotificationQuaduature Encoder Internal TMRs


Stepper Motor Design Flow Chart

Motor Phases?

Micro-Stepping(Half-Stepping)

2 Phase (Bi-polar)1 Phase (Uni-polar)

Commutation2 PWMs or Firmware2 H Bridges

Commutation1 PWM/Phase or Firmware1 0r 2 N-FET Driver/Phase

NoFull SteppingMicro-Stepping

(Half Stepping)8 I/O Pins

Yes Yes

Any PIC MCU ordsPIC DSC

1 or 2 I/O Pins/Phase

NoFull Stepping

Any PIC MCU ordsPIC DSC


Stepper Application Resources

This class is an introduction into stepper motors, how they work, and how to use them in your designs. The anatomy and functional characteristics of the stepper motor will be discussed, along with common drive topologies, basic control circuits and some basic current limiting configurations. In addition, resonant and anti resonant behavior, its root cause, and techniques for dealing with it, will also be discussed. Demonstrations will be used to reinforce topics covered

Stepping Into Stepper Motors1254 STM

Masters Class

Microstepping a stepper motor increases stepping accuracy and reduces resonance in the motor. The two PWMs in the PIC18C452 can be used to control the voltage to the windings of a bipolar stepper motor.

Stepper Motor Microstepping with PIC18C452AN822

If you are not familiar with how a Stepper motor works, this is a good place to start. This application note covers different types of stepping motors: variable reluctance, permanent magnet and hybrid. Single-stepping, halfstepping, microstepping and current limiting.

Stepping Motor FundamentalsAN907

This application note describes how to drive a bipolar stepping motor with the PIC16F684. The Enhanced Capture Compare PWM (ECCP) module is used to implement a microsteppingtechnique known as hightorque microstepping.

Stepper Motor Control using the PIC16F684AN906

Stepper


Motor Control Development Tools


Low-Cost BLDC/PMSMHardware Development Tools

The PICDEM™ dsPIC30F MCLV development board (DM183021) is intended for low-voltage (up to 48V), BLDC applications up to 48 Volts at 1 Amp. It provides a low-cost method for users to evaluate and develop motor control applications using 28-pin dsPIC30F motor control products.

The PICDEM dsPIC33F MCLV development board (DM330021) is intended for low-voltage BLDC applications up to 48 Volts at 10 Amps. It provides a low-cost method for users to evaluate and develop motor control applications using dsPIC30F or dsPIC33F motor control products via a PIM or 28-pin SOIC socket. Serial interfaces include: RS232C, CAN, LIN and USB (for RTDM). Feedback support includes: Hall-Effect Sensors, Shaft Encoder and 3 shunt resistors.


Advanced Motor Control Development System

• Our advanced motor control development systems use a modular approach. Start with either the dsPIC30F MC1 development board or the dsPIC33F Explorer 16 development board with PICtail™ Plus Motor Control Interface board. Then add either the High- or Low-Voltage Power Module and optionally a BLDC or ACIM motor.

• Shown here is the system for dsPIC33F based development, using the Explorer16, the PICtail Plus Motor Control Interface Board, the Low-Voltage Power Module and a BLDC motor (Part #AC300020)


Data Monitor and Control Interface


SummaryToday we covered:

The characteristics, features and, applications of the most popular electric motor types including:

DC Brush MotorDC Brushless MotorPermanent Magnet SynchronousAC Induction MotorStepper MotorSwitched Reluctance Motor

The control algorithms and resources available


Microchip Improves Motor Efficiency

DSP Resource On-ChipNoise Profile Diagnostics

Free SoftwareMigrate from Brushed to Brushless Motors

Improve Reliability

Multiple S&H ADCBetter Loop Response

Free SoftwareIncorporate Field Oriented ControlBetter Torque Control

1% Internal OscillatorRemove Crystal

Optimized Feature SetEasily Migrate to other DSC’s in Portfolio

6 x 6 mm small packagesIntegrate controller on motorCost Reduction

PWM with 2 Time basesIntegrate PFC + Motor Control

Free Software, 4 S&H ADCRemove Expensive Sensors

Free SoftwareIncorporate Sinusoidal ControlNoise Reduction

Free SoftwareIncorporate Field-Oriented Control

PWM with 2 Time basesAdd Power Factor CorrectionEnergy Savings

Microchip has the solution!MethodNeed


• For resources and information for motor-control applications, visit Microchip’s Motor Control Design Center at: www.microchip.com/motor• Microchip Application Notes for Motor-Control Applications:

Using the dsPIC30F for Sensorless BLDC Control AN901Using the dsPIC30F for Vector Control of an ACIM AN908Sensored BLDC Motor Control Using dsPIC30F2010 AN957An Introduction to ACIM Control Using the dsPIC30F AN984Using the dsPIC30F2010 for Sensorless BLDC Control AN992Sinusoidal Control of PMSM Motors with dsPIC30F AN1017Sensorless FOC for PMSM using dsPIC AN1078Sensorless BLDC using BEMF IIR Filtering AN1083Sensorless BLDC Control with Back-EMF Filtering AN1160Using a Majority FunctionGetting Started with the BLDC Motors and dsPIC30F GS001Measuring Speed and Position with the QEI Module GS002Driving ACIM with the dsPIC® DSC MCPWM Module GS004Using the dsPIC30F Sensorless Motor Tuning Interface GS005

Resources


Microchip Motor Control Web Site

• For more information, check out the Microchip Motor Control web site at http://www.microchip.com/motors

• Investigate applications by motor type

• Download a web seminar

• Sign up for a training class

• Get answers to technical questions


ReferencesFitzgerald, Kingley, Kusko, Electric Machinery, 1971, McGraw Hill R. Krishnan, Electric Motor Drives, 2001, Prentice HallDC Motors, Speed Controls, and Servo Systems, 1980 Electrocraft CorporationNovotny, Lipo, Vector Control and Dynamics of AC Drives, 2003, Oxford PressBose, Modern Power Electronics and AC Drives, 2002, Prentice HallHanselman, Duane C., Brushless Permanent-Magnet Motor Design, 1994, McGraw-Hill


Thank You for Attending!


1253 IMC

Appendix


1253 IMC

Motor Interface/Driver


Position Sensing


ResolverHigher Resolution. (i.e. 1024 Different States per Rev)A/D Module + Processing PowerResolver Externally Mounted (More Expensive)Provides Absolute position feedback Cosine

Sine

Resolver Output

Rotor Angular Position

0º

180º

360º

Sensing Position of a BLDC


Optical EncoderHigh Resolution. (i.e. 500 Interrupts per Rev)Special QEI Module + Some MathOptical Encoder Externally Mounted (Expensive)Useful for servo applications due to resolution

INDEX

QEB

QEA

0º

180º

360º

Optical Encoder Output




Hall EffectLow Resolution (i.e. 30 Interrupts per Rev)Simple External Interrupt I/Os1 to 3 Hall effect sensors (Less Expensive)Standard position sensing for low-cost applications

Hall A

0º

180º

360º

Hall B

Hall C

Hall Effect Sensors




Position Sensing InterfaceQEI Module senses motor speed and positionThree Input Quadrature Encoder

Phase APhase BINDEX signals

16-bit position counterChange NotificationInput Capture

3-phInverter

VBUS

AN6AN0QEAQEB

INDEX

AN7

PWM3HPWM3LPWM2HPWM2LPWM1HPWM1L

FLTA Fault

IBUSAN1

120 - 240VAC

BLDC Motor

IncrementalEncoder

PIC

®M

CU

or d

sPIC

®D

SC

Rectifier


Sensorless Position Detection

Reliability – especially aerospace, militaryPhysical space restrictions – axial lengthIssues surrounding sealing of connectionsApplications where rotor runs “flooded”Manufacturability – alignment and duty cycle toleranceCost – especially on low power systems


What is BEMF?When a DC motor spins, the PM rotor, moving past the stator coils induces a electrical potential in the coils called Back EMFBEMF is directly proportional to speedBEMF = RPM/KvIn order to sense BEMF we have to spin the motor

BEMF

Motor

R L


BEMF Motor Speed Sensing


BLDC Motor Back EMF

A

C B

DC+

DC-

Back EMF

Phase A and C are energizedInactive Phase B has induced Back EMFNormally the phase which is not energized, is monitored for Back EMFImportant: Motor has to be spinning


Comparing the BEMF Voltage to Half the DC Bus Voltage


Comparator ModuleDual comparators with fast 20 ns response timeEach comparator has 3 selectable inputs (Cx+, Cx-and voltage reference) for its two pinsProgrammable voltage reference (16 stage resistor ladder network and dual voltage ranges)Programmable output polarityOptional output pin and interrupt on changeOptional wake up from Sleep Mode


Current Sensing


Resistive Low Side Current Sensing


Resistive High Side Current Sensing


Magnetic Current Sensing


ADC ModuleUp to 16 analog inputs (up to 32 on dsPIC33E) 10-bit Resolution with < +1 LSB/ > -1 LSB DNL error (dsPIC30E)10-bit/12-bit Resolution with < +1 LSB/ > -1 LSB DNL error (dsPIC33F/33E)Sample time - 154 nS1 us conversion time (1.1 Msps) 10-bit mode2 us conversion time (500 ksps) 12-bit mode4 Sample and Hold circuits 10-bit mode (1 S&H in 12-bit mode)External VREF+ and VREF-Programmable sampling sequence

16-sample, dual-ported result bufferScan modeAlternate sample mode

Multiple conversion trigger sourcesSelectable result formatsConversions in Sleep and Idle

3-phInverter

VBUS

AN6AN0QEAQEB

INDEX

AN7


FLTA Fault

IBUSAN1

BLDC Motor

IncrementalEncoder

PIC

®M

CU

or d

sPIC

®D

SC

120 - 240VAC

Rectifier


Motor Driver or Inverter


High Frequency CarrierDuty Cycle Varied Over Time to Generate a Lower Frequency Signal

+V

PWM1H

PWM1L

3 PhaseBLDC

PWM2H

PWM2L

PWM3H

PWM3L

PWM with Inverter


Motor Control PWM ModulePWM Module drives motorUp to Four PWM generatorsSeveral options allow PWM to drive many circuit types

AC MotorsDC motorsPower supplies

High frequency @ more bits = better control of motor operationFault detection for safe operation

3-phInverter

VBUS

AN6AN0QEAQEB

INDEX

AN7


FLTA Fault

IBUSAN1

BLDC Motor

IncrementalEncoder

PIC

®M

CU

or d

sPIC

®D

SC

120 - 240VAC

Rectifier


Transistor Considerations

Winding

Vsupply



Winding

Vsupply



Winding

Vsupply



Winding

Vsupply



Winding

Vsupply

P-Channel

N-Channel



Winding

Vsupply

N-Channel

N-Channel


Other Considerations

Choosing a Power Switching Element:Based on applicationMotor specifications

VoltageCurrentPower ratings

Current limiting required if driving the motor at higher than rated voltages


Selecting The Inverter SwitchElement

PLOSS = Irms * 2 * RDS-ON

where:RDS-ON = drain-to-source

on-state resistanceIrms = drain-to-source rms current

PLOSS = Iave * VCE-SAT

Where:VCE-SAT = collector-to-emitter

saturation voltageIave = collector-to-emitter average current

MOSFETMOSFET IGBTIGBT

NN--ChannelChannel NN--ChannelChannel


Gate Charge

Vdrv CGS

Rdrv

on

off

turn-on turn-off

t1 t2t3

t1t2t3

VthVpl

VDR

VGS

VDS

IG

0

0

0

2 2 Crss(VDS(t)- VDS(t-1))

2Ciss(VDR)

2PDRIVE - +[ ]fSW

The gate drive current must not only overcome the Ciss=Cgs+Cds, but also the energy injected into the gate from the Crss = Cds.


MOSFET or IGBTMOSFETs for application voltages < 250V

The selection of IGBTs with rated voltages below 600V is very small.

IGBTs for application voltages > 1000VAs the voltage rating of the MOSFET increases, so does the RDS-ON and size of the device. Above 1000V, the RDS-ON of the MOSFET can no longer compete with the saturated junction of the IGBT.

Application-specific between the 250V and 1000V Factors power dissipation, switching frequency and cost of the device.


Hints for Design and De-rating

Voltage rating of the device is de-rated to 80% of its valueThe maximum junction temperature of the device should not exceed 120ºC at maximum load and maximum ambientMinimize trace inductance going to the leads of the motor from the drive circuitryThe current rating for the switching element must also be able to withstand short circuit and start-up conditions


Gate Driver Functions

Minimizes turn-on and off timesProvides power to keep the power switch onProvides reverse bias in order to ensure the switching device remains in the off-stateAmplifies the control signalProvides protection from over current

Feedback would be requiredProvides a large current for initiating turn-on, then large gate voltage at low current levels for the duration of the turn-on periodMay provide electrical isolation where requiredMay provide deadtime (blanking time)


High Voltage FloatingMOS Gate Driver

Block Diagram


Gate Drive Requirements Of High-side Devices

Gate voltage must be 10 V to 15 V higher than the drain voltageThe gate voltage must be controllable from the logic, which is normally referenced to ground The power absorbed by the gate drive circuitry should not significantly affect the overall efficiency


Power Dissipation in a HVICLow voltage static losses (PD,q(LV)) are due to the quiescent currents from the low voltage supplies

(e.g., VDD, VCC and VSS). In a typical 15 V application these losses amount to approximately 3.5 mW at 25°C and increase to approximately 5 mW at TJ = 125°C

Low voltage dynamic losses (PD,SW(LV)) on the VCC supply are due to

Capacitor is charging or discharging through a resistor, half of the energy that goes into charging the capacitance is dissipated in the resistorDynamic losses associated with the switching of the internal CMOS circuitry

High voltage static losses (PD,Q(HV)) are mainly due to the leakage currents in the level shifting stage.High voltage switching losses (PD,SW(HV))

Due to the level shifting circuitDue to the charging and discharging of the capacitance of the high-side p-well


High Voltage Integrated Circuits


High Voltage Integrated Motor Drivers

Configurable phase commutation delay

Current monitoring

Miniature TSSOP20

PWM output to drive H-bridgeVariable or fixed speed control of single-phase brushless dc fans, blowers and pumps

ZXBM1015 single-phase motor predriver

Zetex Semi-conductors

Phase sequence generator

PWM controllerSmart motor drivers6208/6228/ 6235/6229

Dual DMOS full bridge6226/6207/ 6227/

PowerDIP24, PowerSO36 and SO24

Two-phase stepper motor driver has:

Dual dc or bipolar stepper motors and BLDC motors

L6205/6225/6206/STMicro-electronics

600-V ac 3-phase systems2114SS/21141SS

(IR21381Q /2177S/21771S/

400-V ac 3-phase systems

1200-V rating on current-sensing ICs

BLDC and ac motor drives2214SS/22141SS

64-lead MQFP,16-lead SOIC, and 24-lead SSOP

1200-V IGBT gate driver ICs protect against ground faults, shoot-through, and short to supply rails

AC induction motor drives up to 15 hp

IR22381Q /2277S/22771S/

International Rectifier

Needs no heatsink for motor drives up to 180 W

11-pin mini SIPHalf-bridge FredFET with gate driver

Two- and three-phase half-bridge inverter motor drives for ac induction and BLDC motors

IR3103 motor drive ICInternational Rectifier

29 mm × 12 mm, 23-lead Tiny-DIP

Modules combine six fast-recovery MOSFETs and three half-bridge, high-voltage ICs

BLDC motors in home appliances (below 100 W)

FSB50250 and FSB50450 Motion-Smart Power Modules

Fairchild Semi-conductor

PackageFeaturesApplicationsModelVendor


Power Electronics Gate Drive Stages

Fault detection circuitry

Conditioning of Feedback Signals

Optocouplers Drive Isolated Hall-EffectCurrent Transducer

Signals from/to dsPIC® DSC

Fault signals

Currents measured

IsolatedSwitchingSignals

Switchingsignals

Phase voltagesPhase voltages

Isolated Three Phase Inverter


Driver Application Resources

Driving ACIM with the dsPIC® DSC MCPWM ModuleGS004

Measuring Speed and Position with the QEI Module GS002

The DC Motor Control Tips ‘n Tricks document has lots of information about driving brush DC motors.

DS41233

Electronic motor control for various types of motors represents one of the main applications for MOSFET drivers today. This application note discusses some of the fundamental concepts needed to obtain the proper MOSFET driver for your application.

Determining MOSFET Driver Needs for Motor Drive ApplicationsAN898a

Sensors are a critical component in a motor control system. They are used to sense the current, position, speed and direction of the rotating motor. In most motor control systems, several sensors are used to provide feedback information on the motor. These sensors are used in the control loop and to improve the reliability by detecting fault conditions that may damage the motor.

Motor Control Sensor Feedback CircuitsAN894

Motor Interface/Driver


Motor Control Vocabulary


Motor Control VocabularyMost Commonly found Motor Types

DC BrushDC BrushlessPMSMAC inductionStepper MotorSwitched Reluctance

General Functions for Motor ControlTimerAnalog to Digital ConverterPulse Width Modulation



Electricity BasicsAC is Alternating Current

Think of the wall socketIt is how electricity is generated!Motor is a reverse of a generator!

DC is Direct CurrentThink of a batteryArmature is energized in a DC motor



Motor Structure Armature

Device that turns in a motorSometimes called “rotor”Energized in a DC motor

StatorThe “outside” caseEnergized in an AC motor



Motor Structure (continued)Commutator

Only found in DC motorsPermits generation of direct current in a rotating machine

TorqueApplication of force“Think of turning a bolt”



Motor Structure (continued)Poles

AC Induction motorNumber of magnetic on poles stator winding See Synchronous speed

PMS MotorNumber of PM poles on the rotorMechanical vs. Electrical revolutions

Brush DC MotorStronger magnetic field (torque)Poles do not determine speed



Torque RippleVariation in torque (Commutation)Expressed as a percentage of torque

SlipRotor unable keep up with stator fieldCaused by load



Field WeakeningDecrease strength of the magnetic fieldIncreases motor speedDecreases torque



InverterElectronic deviceConverts fixed frequency and fixed voltages to variable frequency and voltageElectronic speed control of an AC motor



Synchronous Speed (ACIM)Speed of the rotating magnetic field in stator winding Rotor moves with the rotating stator fieldSpeed = 120 * freq

Poles



Electrical Revolution (BLDC)Rotor moves with the rotating stator fieldSix Steps per Rotor pole pairElectrical RPS = Mechanical RPS

Rotor Pole Pairs



DynamometerCalibrated dynamic loadMeasures motor

Output torque Speed Efficiency



Open Loop ControlNo feedback – basic control suitable for systems with simple loads such as fansTimer based solutionMay have current sense for overload / stall conditions

Closed loop controlPosition / speed feedback from sensor(s)Used for accurate speed and control



Two Types of Closed loop control

With SensorHall Effect, Resolvers, QuadratureEncoders

Without Sensor (“sensorless”)Measures the current flowing in the motor

Measure back EMF for motors with magnetsMeasure inductance (L) in switched reluctance motors


Motor Control VocabularyEmbedded Control Algorithms (examples)

More complex than using timersEmployed in closed loop systems

PI - Proportional IntegrativePID - Proportional Integrative DifferentialAlgorithms require

MeasurementCalculationControl

Requires microcontroller performance


TrademarksThe Microchip name and logo, the Microchip logo, Accuron, dsPIC, KeeLoq, KeeLoq logo, MPLAB, PIC, PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.FilterLab, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL, SmartSensorand The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A.Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, PICkit, PICDEM, PICDEM.net, PICtail, PIC32 logo, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Total Endurance, UNI/O, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.SQTP is a service mark of Microchip Technology Incorporated in the U.S.A.All other trademarks mentioned herein are property of their respective companies.© 2008, Microchip Technology Incorporated. All Rights Reserved.

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