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• TI Digital Motor Control SolutionsTI Digital Motor Control Solutions

Texas Instruments Incorporated 2005No reproduction permitted without prior authorization from Texas Instruments. SPRB167A

1H2004 Slide 1

• Agenda Timeline Motor Control Fundamentals 25 min

AC Induction and Permanent Magnet Motors

Scalar and Vector Control

Applications: Smarter controllers, high performance, lower cost 15 min

Controller Selection 10 min

Motor Control Collateral Overview 25 min

Development Tools Overview: Faster HW+SW Development

Modular Software Libraries: Development Accelerators

Incremental Build Technology: Easy Deployment

Completing the signal chain: TI Analog and Communications 25 min

Get Started Today with TI! 5 min

1H2004 Slide 2

• Three Phase Machine Fundamentals

Conceptual Practical

Three phase machines have three windings, separated in phase by 120- a third of a rotation.

1H2004 Slide 3

• Three Phase Machine Fundamentals

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

1 24 47 70 93 116 139 162 185 208 231 254 277 300 323 346t

ia ib icPhase currents

The three phase winding produces three magnetic fields, which are spaced 120apart physically.

When excited with three sine waves that are a 120 apart in phase, there are three pulsating magnetic fields.

The resultant of the three magnetic fields is a rotating magnetic field.

A`

A

Fa

B

C`

C

B`

ia

Fb

Fc

1H2004 Slide 4

• A`

A

Fa

B

C`

C

B`

ia

Fb

Fc

Fs

q (imaginary)

d (real)

\$ sin( ). sin( ). sin( ).F F t e F t e F t es a i b o i c o io o o= + + + + 0 120 240120 240

\$ .F F es s j t= \$F F jFs d q= +

Three Phase Machine Fundamentals

For instance, a 3 phase machine, with:60Hz Three Phase Supply; and 4 poles per phase will have a synchronous speed of 1800 r.p.m.

Pf 120 r.p.m.)(in Speed =

phaseper motor, for the poles of # P and

frequency,supply AC f=

=

1H2004 Slide 5

• Permanent Magnet Motor Operation

1H2004 Slide 6

Back EMF

(v) t

tStator Current

(Is)

The interaction between the rotating stator flux, and the rotor flux produces a torque which will cause the motor to rotate.

The rotation of the rotor in this case will be at the same exactfrequency as the applied excitation to the rotor.

A`

B

C`

AB`

C N

S

F

F

Stator field

Rotor field

This is an example of Synchronous operation.

• Internal View: Induction Motor Rotor

1H2004 Slide 7

• ACI Operation FundamentalsA`

A

B

C`

C

B`

ia

Ft

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

1 24 47 70 93 116 139 162 185 208 231 254 277 300 323 346

ia ib icPhase currents

Im

Re

120o Ia

~

Ib~

Ic~

Current Phasors

The induction machine has a rotor that is a closed circuit in the case of the squirrel-cage induction motor it is two rings joined by bars along the rotor axis.

The rotor when placed in a moving magnetic field will have induced currents, which produce an induced magnetic field.The interaction of these two magnetic fields produces the rotational torque.

1H2004 Slide 8

• Agenda Timeline Motor Control Fundamentals 25 min

AC Induction and Permanent Magnet Motors

Scalar and Vector Control

Applications: Smarter controllers, high performance, lower cost 15 min

Controller Selection 10 min

Motor Control Collateral Overview 25 min

Development Tools Overview: Faster HW+SW Development

Modular Software Libraries: Development Accelerators

Incremental Build Technology: Easy Deployment

Completing the signal chain: TI Analog and Communications 25 min

Get Started Today with TI! 5 min

1H2004 Slide 9

• Scalar V/F control of 3-ph Induction Motor

Vs(volt)

f (Hz)fc frating

Vrating

0

TORQUE

MAXIMUMTORQUE

NOMINALTORQUE

SPEEDNOM SPEED

VOLTAGE

Vo

LOW SPEED

+ Simple to implement: All you need is three sine waves feeding the ACI

+ No position information needed.

Doesnt deliver good dynamic performance.1H2004 Slide 10

• Limitations of the Scalar TechniqueACCELERATION DECELERATION

TIME

TORQUE

Torque oscillationgenerates uncontrolled

current overshoot:

High peak current:In V/f the rotor flux and current are not controlled: Current reaches values based on circuit parameters.

Poor response time:A solution to minimize these current overshoots is to decrease the performances of the speed regulator.Slow speed regulator poor mechanical behavior.

1H2004 Slide 11

• Stationary and Rotating Reference Frames

Two phase orthogonal reference frame

t

t

R/2

a

b

R2/3

2/3

2/3c

Three phase reference frame

t

DRQ

rotort

t

IQ

ID

Rotating Orthogonal Reference Frame

/2

1H2004 Slide 12

• Motor Flux Interaction

TorqueT

s and r constantTorque = sr sin()

DR

Q

rotor

S

1H2004 Slide 13

• Vector Control of 3-Ph Induction Motor

FOC is a control strategy for 3-ph AC motors, where torque and flux are independently controlled.

The approach is imitating the DC motors operation.

Direct FOC: rotor flux angle is directly computed from flux estimation or measurement.

Indirect FOC: rotor flux angle is indirectly computed from available speed and slip computation.

1H2004 Slide 14

• Maintain the load angleat 90

Field Oriented Control - Vector Control

A`

B

C`

AB`

C N

S

q=90F

F

+ No torque ripple

+ Better dynamic response

Need good knowledge of the rotor position

Back EMF (v)

Stator Current (Is)

t = constant

t

t

t

1H2004 Slide 15

• C28x Controllers

1H2004 Slide 16

• PMSM FOC with TMS320F2812 DSP

PowerInverter

Motor

vas*

vbs*Inv. Park

rias

ibs

vqs*

vds*

PI

ids*

iqs*wr*

wr

Park

PI

PI

Clarke

SpaceVector Gen.

PWM+

Driver

Ta

Tb

Tc

PWM1PWM2

Driver

PWM3PWM4PWM5PWM6

ias

ids

iqs

AngleSpeed Calculator

r

TMS320F2812 DSP controller

QEP+ driver Phase

Index

Phase Encoder

1H2004 Slide 17

• ACI FOC System with TMS320F2812 DSP

PowerInverter

ACI

vas*

vbs*

Inv. Park

lr lrias

ibs

vqs*

vds*

PI

ids*

iqs*wr*

wr

Park

PI

PI

Clarke

SpaceVector

Gen.

PWMDriver

TaTb

Tc

PWM1PWM2

Vdc

ibsIleg2_Bus

Driver

PWM3PWM4PWM5PWM6

ias

ids

iqs

Phase Voltage

Cal.TaTbTc

vasvbs

Flux Est.

Speed Est.

iasibs

iasibs

lrlarlbr TMS320F2812 DSP

controller

1H2004 Slide 18

• FOC TMS320F2812 DSP + Resolver

PowerInverter

Motor

vas*

vbs*Inv. Park

rias

ibs

vqs*

vds*

PI

ids*

iqs*wr*

wr

Park

PI

PI

Clarke

SpaceVector Gen.

PWM+

Driver

Ta

Tb

Tc

PWM1PWM2

ibs

Driver

PWM3PWM4PWM5PWM6

ias

ids

iqs

AngleSpeed Calculator

r

TMS320F2812 DSP controller

ResolverPosition

DetectionCosSin Resolver

1H2004 Slide 19

• Cost Effective High AccuracyPosition Measurement by Resolver

1H2004 Slide 20

• Sensored AC Induction Motor DTC Drive

PowerInverter

Motor

Torque controller

r*

State Selector

TMS320F2812 DSP controller

PWMGenSpeed Controller

Input power stage

Input power stage

Flux and Torque calculator

Communications modules

SCI CAN

Current and voltage vector calculator

C

A

P

T

U

R

E

I

n

p

u

t

s

1H2004 Slide 21

• BLDC and PMSM Motor Types Both (typically) have permanent-magnet rotor and a

wound stator BLDC (Brushless DC) motor is a permanent-magnet

brushless motor with trapezoidal back EMF PMSM (Permanent-magnet synchronous motor) is a

permanent-magnet brushless motor with sinusoidal back EMF

300 900 1500 2100 2700 3300 300 90060000 1200 1800 2400 3000 3600 600

Phase A

Phase B

Phase C

ia

ib

ic

e

e

e

Ea

Hall A

Hall B

Hall C

Back EMF of BLDC Motor

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0.00

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1.00

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1 24 47 70 93 116 139 162 185 208 231 254 277 300 323 346t

ea eb ec

Back EMF of PMSM

A`

B

C