renesas jani seminar 2

Implementing Embedded Speed Control for AC Induction Motors

Yashvant Jani, Director of Applications Engineering Leonard Haile, Applications Engineer

Renesas Technology America, Inc. 450 Holger Way San Jose, CA 95134 USA

TEL: 408-382-7500 FAX: 408-382-7501E-mail: [email protected]

Web: www.renesas.com

Topics Outline

• Induction Motor principles– Physics of induction motors– Induction motor construction

• Control hardware – typical layout• Modulation techniques

– Sinusoidal, Quasi-sinusoidal & Space Vector• Control methods

– Open loop algorithms– Closed loop algorithms

• MCU performance benchmark• Summary

Physics of Induction Motors• Current passing through a conductor creates magnetic

field– Direction of magnetic field is determined by the

right hand rule• Changing magnetic field produces current in a

conductor– Direction of current is determined by right hand

rule• Electromagnetic Induction

– Changing current induces changing magnetic field around it.

– A conductor placed in this field has induced current and induced magnetic field

• Interaction between two magnetic fields and two currents in stator and rotors produce the torque

• Torque is proportional to the magnitude and frequency of the current in stators– Torque = K (E1/f1)2*s/R2

I Φ

dΦ/dt

dI

dIdΦ

-dφ

-di

dΦ/dtdI1 I2

Torque α mag & freq of I1

Induction Motors

• Motors operate on principle of Induction and hence the name “Induction Motors” is used

• Motors also known as AC motors because Alternating Current (AC) is required

• All AC motors are “brushless”– No mechanical contacts to wear– Requires AC source– If used, inverter creates desired freq and

magnitude of AC• AC induction motors for lower cost

applications– Single speed applications: fan, blower,

pump, compressor– No control, just start the AC power

source– Relays are used for ON/OFF

Stator Construction

• Stator has windings with lamination to– Create strong magnetic field– Maintain continuous flux

• Three phase motor windings are sinusoidal around the stator to produce a roughly sinusoidal distribution in flux

• When three phase AC voltages are applied to the stator windings, a rotating magnetic field is produced– The rotating magnetic field of the stator drags the

rotor around.

Stator

α

Rotor Construction

• Squirrel cage construction– Behaves like shorted 3-phase

windings– Rotor bars are often skewed to

prevent cogging– No magnets or windings

Rotor

Windings & Slip Angle

Y or StarConnection

Phase A Phase B

Phase CNeutral

iSa + iSb + iSc = 0

Sum of currents is zero

Phase A Phase B

Phase C

DeltaConnection

Vab + Vbc + Vca = 0

Sum of voltages is zero

• Stator has Sinusoidal Flux/Voltage Generation• Rotor rotates at the excitation speed minus slip s

• Stator has two types of connections

Voltage/FluxStator Cross section

A BC D

A

B

C

D

Rotor Cross section

Slip s =(ω-pωm)/ω

Slip S = 1 -Stator Speed

Rotor Speed

Motor Model Per Phase Equivalent Circuit

StatorResistance

Stator LeakageInductance

Stator MagnetizingInductance

Rotor LeakageInductance

RotorResistance

R1 L1

LM

L2

R2s

E1

IsIM I2

MagnetizingCurrent

IsIq

Id

Torque Producing Current

E1f1

( )2

Ks

R2Torque =

V/Hz Control

Torque = K ( i2 )2 R2/s

Torque = (3/2) (P/2) (λm Iq + (Ld – Lq) Iq Id)

• In vector formulation, Torque is proportional to the Magnetizing Flux and current in q-axis

Torque Speed Curve • At constant supply frequency

– The synchronous mechanical angular speed is: ωmSync=ω/p • where p number of pole pairs and ω electrical angular speed [2pf]

– When load is present the rotor speed is lower than the supplied frequency.

• ωm < ωmSync

– Slip: s=(ω-pωm)/ω

Constant Supply Frequency

Torq

ue

Speed (ωr)ωs

Open loopoperating point (stable)

~1.5-3 % S (or below ws)Startingtorque

No torque atsynchronous speed (ωs)

S = 0

Controlled operating point(unstable)

peak torque

motoring

generating S = 1

MaximumEfficiency~5-7% S

Braking

Example:ws = 60 HzS = 1.5 % giveswo = 59 Hz

Typical Control Hardware

MAC/DCIn

put F

ilter

ing

DC Filtering Output Power Stage

MCU

Set Values

DriversSensing

ConditioningFeedbackControl Algorithms

Converter Inverter Mixed VoltageHigh Voltage

VDC

A+

A-

B+

B-

C+

C-

For DC supply, bridge and motor are presented

Typical Motor Drive Configuration

MotorEncoder

Current Feedback

Hall Effect Absolute position feedback**

Absolute Position/Speed feedback

S1

S2

S3

S4

S5

S6

One Shunt

** Generally not used for Induction Motor

ACCT

MCRP Overview• This reference platform has two boards

LCD

MCU

Power supply connection

U, V, W 3-phaseMotor interface

Hall Sensor inputIntegrated Power Module with heat sinkEncoder input

One Shunt

Three LED showing PWM pulsing

SKP

Two DCCT

Built in Back EMF Circuit

Modulation Schemes

Modulation Schemes

• Sinusoidal wave– 180 deg vs. 120 deg drive

• Quasi- sinusoidal wave drive– Add 3rd harmonic for efficiency

• Space vector modulation

What is a 180° Drive？120°Drive & 180°Drive

W

U

V W

U

V

120°Drive 180°Drive

On two of the 3 coil wires, the electricity is always flowing. After every 120 degrees, the positive and the negative is connected to the power supply alternately.

The electricity is always flowing on every coil wires. After every 180 degrees, the positive and the negative change.

Item

NoiseRipple

120°Drive 180°Drive

△ YesTorque-Ripple Yes

◎ NOTorque-Ripple less

Phase detection(back EMF)

○ YesBecause of 60 degree of non-driventime, commutation is easy and simple

△ NOBecause of the dead time, the

commutation is difficult.

Power Usage Only 2 coils used All 3 coils used

W

U

V W

U

V W

U

V W

U

V W

U

V W

U

V

UUVVWW

Vu

Vv

Vw

Iu

Iv

Iw

U_ONU_ON

V_ONV_ONV_ON

W_ONW_ON

Back EMF

Switch pattern

0

0

0

0

0

0

120°PWM Control

UUVVWW

Vu

Vv

Vw

Iu

Iv

Iw

U_ONU_ON

V_ONV_ONV_ON

W_ONW_ON

W

U

V

0

0

0

0

0

0

W_ON

W

U

V W

U

V W

U

V W

U

V W

U

V

Back EMF

Switch Pattern

180°Electric Sinusoidal Wave Drive

180°Drive Operation

• Utilizes entire electrical rotation to rotate the motor vs. 120 deg uses only 2/3 rotation

• Requires dead time register to make sure two power devices do not conduct at the same time for a given phase – e.g. Up and Un do not turn on at the same time

• This operation generally can not use the back EMF signal to detect the rotor position

• Allows various modulation strategies including sine wave & pseudo sine wave

3-Phase Timer on M16C

Dead Time counter

TimerA1=UTimerA2=VTimerA4=W

TimerB2

Positive

NegativeOutput

Buffer Register for 3 Phase

P Signal(Internal）

N Signal(Internal)

Carrier

Di0=”0”,Di1=”1”DiB0=”1”,DiB1=”0”

Di0=”1”,Di1=”0”DiB0=”0”,DiB1=”1”

Di0=”0”,Di1=”1”DiB0=”1”,DiB1=”0”

※Output as Low Active

50 μsec

3-Phase Timer Capabilities • This timer generates complimentary PWM with dead time inserted

between transitions• Dead time to be programmed only one time

• 16-bit registers provide more than adequate resolution

Modulation schemes• 120 deg

• 60 or 120 deg• Upper/lower/both• One at a time

• 180 deg• Sinusoidal• Quasi-sinusoidal• SV-PWM• Custom

120 Deg 6-step modulation• Timer allows modulation during one step – up or down switch

(0,0) (1,0)(DU0,DU1)

Sine Wave Generation

Desired Voltage V0 & Frequency f Carrier wave (Frequency fc )

U = V0 sin θV = V0 sin (θ+120°) W = V0 sin (θ+240°)

θ(n) = θ(n-1)+ΔθΔθ = 2πf / fc

(1) Phase angle θ of a voltage in time t is calculated (2) Corresponding Sin θ value is found from the ROM table (3) Multiplying the sin θ value with modulation ratio a results in PWM values (4) These U, V, and W PWM counts are transferred to RAM.

(V and W phase differences are kept at 120 and 240 degrees to U, respectively.)

Steps for Sine Wave Generation• Three items required: carrier freq fc, Sine freq f and voltage

level Vdc [implying Vmax = Vdc and Vmin = 0]• Example: Fc = 10 kHz, f = 50 Hz, Vdc = 160 volts• Computation results

– Average voltage = (Vmax+Vmin)/2 = Vdc/2 = 160/2 = 80 volts– Vmax = Vdc = ½ Vdc + ½ Vdc * Sin 90 (Sine value is 1) – Vmin = 0 = ½ Vdc + ½ Vdc * Sin 270 (Sine value is -1)– Vpwm = ½ Vdc + ½ Vdc * Sin θn (Sine θn value from Table)– Δt = 1/fc = 1/10000 = 100 μs– Δθ = 2πf/fc = 360 * 50 / 10000 = 360 / 200 = 1.8 deg – This is the angle traversed in Δt time (every carrier frequency)– PWM is computed as:

• θn = θn-1 + Δθ, if θn > 360 θn = θn - 360, Vpwm = ½ Vdc + ½ Vdc * Sin θn• PWM counts @20 MHz is 20*100=2000, Timer B2 is half of this 1000. • 1st PWM for Timer A is PWM1 = 500 + V0*Sin θn & PWM2 = 1000 – PWM1

– V = Vdc/2 @0 deg, V = Vdc @90 deg, V = 0 @270 deg

Sine Wave Generation• One degree resolution results in a table with 360

entries• For integer math, sine values are scaled in 2^13

format (2^13=8192= 1.0 floating point)

IndexMid point

angle Sine valueSine in 2^13

format

Integer value for

Sin1 0.5 0.008726535 71.4877788 712 1.5 0.026176948 214.4415605 2143 2.5 0.043619387 357.3300213 3574 3.5 0.06104854 500.1096359 5005 4.5 0.078459096 642.7369122 6436 5.5 0.095845753 785.1684046 7857 6.5 0.113203214 927.3607272 9278 7.5 0.130526192 1069.270567 10699 8.5 0.147809411 1210.854696 121110 9.5 0.165047606 1352.069987 135211 10.5 0.182235525 1492.873425 149312 11.5 0.199367934 1633.222119 163313 12.5 0.216439614 1773.073317 177314 13.5 0.233445364 1912.384421 191215 14.5 0.250380004 2051.112993 205116 15.5 0.267238376 2189.216777 2189

Three sine waves at a time

-10000

-8000

-6000

-4000

-2000

0

2000

4000

6000

8000

10000

1 41 81 121 161 201 241 281 321

angle

Sine

val

ue

Integer value for uInteger value for vInteger value for w

U phase W phase V phase

Sine Generation

• Lab activity• View the MCRP, motor and PC set-up

for testing• View the High-Performance Embedded

Workbench operation• See Sine wave, quasi-sine wave and

space vector wave on scope

Sinusoidal PWM drive

• Possible to improve control performance and efficiency

• Carrier frequency is preferred for complementary waveform, because it is necessary to keep the symmetry of the output voltage

This method requires a true 3-phase timer unit for proper operation

W

V

U

Inverter Output PWM

U-V

V-W

W-U

0 π 2π

Trapezoidal vs Sinusoidal Commutation

360°300°0° 60° 120° 180° 240°

S1

S2

S3

S4

S5

S6

VA

VB

VC

“BLDC” “PMAC”

Quasi Sinusoidal Modulation

Sinusoidal/Quasi-sinusoidal Wave Drive

⎭⎬⎫

⎩⎨⎧

+⎟⎠⎞

⎜⎝⎛ +=

⎭⎬⎫

⎩⎨⎧

+⎟⎠⎞

⎜⎝⎛ −=

⎭⎬⎫

⎩⎨⎧ +=

θπθ

θπθ

θθ

3sin61

32sin

32

3sin61

32sin

32

3sin61sin

32

Vw

Vv

Vu

⎟⎠⎞

⎜⎝⎛ +=

⎟⎠⎞

⎜⎝⎛ −=

=

πθ

πθ

θ

32sin

32sin

sin

Vw

Vv

Vu

0 10 20 30 40 50-2

-1

0

1

2U V W

time (ms)

mag

nitu

de

Sine curve

0 10 20 30 40 50-2

-1

0

1

2

mag

nitu

de

time (ms)

U V W

With 3rd Harmonic included

U-V phase

fc = 20kHz, f=50Hz

U-V phase

fc = 20kHz, f=50Hz

Comparison of Sine & Quasi-sine

Comparison of Sine & Quasi-sine waveforms

-10000

-8000

-6000

-4000

-2000

0

2000

4000

6000

8000

10000

1 29 57 85 113 141 169 197 225 253 281 309 337

Angle

Inte

ger v

alue

Sine wave

Quasi sine wave

• Quasi- sine wave allows nearly 15% higher bus utilization• Torque is increased due to this high current

Space Vector Modulation

Basics of Space Vector• A 3 phase inverter is made by 6 switching devices.• The purpose is to calculate the output desired vector as a linear

combination [in the time domain] of 2 fundamental vectors.• Each fundamental vector is given by a fixed driving combination.

va vb vc

a

a’

Vdc

b

b’

c

c’α

β

U0 (1,0,0)

U60 (1,1,0)U120 (0,1,0)

U180(0,1,1)

U240 (0,0,1) U300 (1,0,1)

S0

S1

S2

S3 S4

S5

Fundamental Space VectorsInverter Structure

Unull=(000) Uall=)111)

SV PWM• When fixed carrier frequency is used, angle is

easy to calculate and also the ON time for each switch

Here a is the angle between one base vector to the applied U vector

A, B and C are the typical U, V & W values

Space Vector Output• Carrier Freq is 20kHz

Why Use Space Vector?• Improves DC bus utilization

– Instead of being able to create √2 /2 Sin() magnitude voltage we can create √3 /2 Sin() magnitude voltage

• Reduces EMI– Less transistors are switching.

• Reduces switching losses– Requires only two windings switching during

60 degree electrical portion of motion. Third winding can fixed high or low.

– Special firmware is necessary with special timer features

ACIM Control Methods

Modulation Schemes

• Modulation schemes– Sinusoidal wave drive (180 deg drive)– Quasi- sinusoidal wave drive– Space vector modulation

• Open loop control algorithms– V/f control

• Closed loop control algorithms– Sensor feedback: scalar, vector – Sensorless: scalar & vector control

180deg Sinusoidal Drive （M16C/28) a) V/f control (open loop)

• Without Pos. Sensor)

b) Scalar PI control (closed loop)• With Pos. Sensor)

Under development c) Vector Control (With Pos. & Current Sensor)

d) Sensor-Less Control (With Current Sensor)

e) Sensor-Less OSCD Control (Without Any Sensor)

ACIM Control Methods

Scalar controlScalar controlV/F controlV/F controlWay to control Open loop Feedback

Speed controlConstant torque control

Low accuracy High accuracy

Torque control

Others

Indirect – OK under certain conditions Indirect but better torque control

Dynamic control difficult Indirect torque control only

Micro Computercontrol

Output PWM pattern correspond to speedcommand value from Data table

Speed detected by sensor, closed loop Speed control, No Current control

• Simple configuration• Adjustment is easy

• Speed detect is necessary • Additional sensor cost

Inverter part

3 phase IM

MicroComputer

Driver

a) V/f Control a) V/f Control

Sinusoidal Wave

3phase IM Control Techniques (1)Inverter part

3 phase IM

MicroComputer

DriverTachometer(Speed)

b) Scalar Control b) Scalar Control

Vector ControlVector ControlV/F controlV/F controlWay to control Open loop Feedback – closed loopSpeed controlConstant torque control

Low accuracy High accuracy

Torque control

Others

OK under certain conditions Best among all

Dynamic control difficult Best among all


Output PWM pattern correspond to speedcommand value from Data table

MCU detects speed, measures currents using ADC, and makes adjustments for PWM

• Simple configuration• Adjustment is easy

• Speed & current detection is necessary • Additional cost for sensor & DCCT

Inverter part3 phase IM

MicroComputer

Driver

a) V/f Control a) V/f Control

Sinusoidal Wave

3phase IM Control Techniques (2)Inverter part

3 phase IM

MicroComputer

Driver

DCCT for Current

Encoder orTachometer for Speed

c) Vector Control c) Vector Control

Sensorless 2DCCT ControlSensorless 2DCCT ControlVector controlVector controlWay to control Closed loop Closed loop with estimationSpeed controlConstant torque control

Very High accuracy High accuracy

Torque control

Others

Best among all Very High




MCU estimates (!) speed, measures currents using ADC, and makes adjustments for PWM for torque control

• Speed estimation requires more computing • Current detection is necessary • DCCT cost only, NO cost for position sensor

3phase IM Control Techniques (3)


MicroComputer

Driver

DCCT for Current


c) Sensorless 2DCCT Control c) Sensorless 2DCCT Control Inverter part

3 phase IM

MicroComputer

Driver

DCCT for Current



X


Sensorless OSCD ControlSensorless OSCD ControlVector controlVector controlWay to control Closed loop Closed loop with estimationSpeed controlConstant torque control

Very High accuracy High accuracy

Torque control

Others





MCU estimates (!) speed, measures currents using OSCD method & ADC, and makes adjustments for PWM for torque control

• Speed estimation & OSCD current measurement requires even more computing

• NO DCCT or position sensor cost

3phase IM Control Techniques (4)


MicroComputer

Driver

DCCT for Current


e) Sensorless OSCD Control e) Sensorless OSCD Control Inverter part

3 phase IM

MicroComputer

Driver

DCCT for Current



X


X

Voltage/Frequency Motor Control• Control based on the following assumptions:

– The motor impedance increases when the frequency increases.– We want to have fixed current as much as possible.– So it is simple to increase the motor speed by increasing the

frequency and the related voltage.

Generally, wmin and wmax depend on the motor and wops is determined by the system configuration

No Load Resulting Current

100%

50%

wmin wops wmax

DC BusVoltage

Frequency

++ Operational Points

+ +

+

+ + ++

What accuracy is necessary?

V/F Motor Control

• Advantages– No current measurement required.– No speed measurement required.– Very simple algorithm.

• Weakness– No feedback on speed so:

• in case of variable load, a speed sensor must be added and the algorithm become more complex.

– No feedback on current so:• over-current condition is possible.

– No flux control so:• Low motor efficiency.• Low maximum torque achievable.

V/f Control without any Sensor

Sine VoltageCalculations

PWM

invertervu*,vv

*,vw*

6ω1

Speed Commandωr

* TBL Motor

Voltage & Freq determined from

table

TBL – Table Look Up for Freq and Voltage

• Simple to achieve with a true 3-ph Timer unit• Table stores sine values• Carrier freq 16-20 kHz range• Able to run V/f control without position sensor

Scalar Control with a Rotor Position Sensor

Sine VoltageCalculations

PWM

invertervu*,vv

*,vw*

6ω1

Speed command ωr*

ASR+-

ωr

Motor

input captureand

counter

Rotor position θdFor correction

Rotating speed ωr

Position sensor encoder or tacho

ASR - Auto Speed Regulator - PI Controller

• Simple to achieve with a true 3-ph Timer unit• Table stores sine values• Carrier freq 16-20 kHz range• Able to run closed loop PI control with position sensor

V/f Performance for M16C

• V/f open loop testing– without feedback and – with feedback of tacho pulse

• Two major interrupts– PWM output via TB2 timer channel– Tacho input via Timer S

• Frequency and voltage changes made only when the U phase is near zero angle.

PWM Interrupt Processing

• Carrier Frequency 16 kHz, interrupt time 62.5 ms– Can be easily changed to any value

• Four steps done in this PWM interrupt– Computing angle index– Calculating u, v and w using sine table (look-up)– Max-min checking– Loading the timers

• Peak voltage and desired frequency decided by a time based profile or another task

• Updates to desired speed & peak voltage is processed when U angle is near zero– Two flags are used to minimize processing

CPU Time Measurements

• Lab activity• Perform code review for measuring

execution time• Measure execution time for the PWM

interrupt via scope• View the scope pictures• CPU bandwidth analysis with the time

measurements performed

Performance Results (1)

• Interrupt execution time for this code is 33.56 μs– About 54% CPU usage,

still more than 40% left for other tasks

• Interrupt execution time remains the same at 20kHz carrier frequency– CPU bandwidth usage

about 66%

Performance Results (2)• Code optimization in

several areas– Sin(W) is computed from

Sin(U) and Sin(V) to avoid multiplication and table lookup

– Max-min checks are deleted (guarantee by design)

• Measured time now is 14.31 μs

• Standard code 33.56 μs vs optimized 14.31 μs– CPU usage only 23%– More than 50%

optimization

Sensor Processing (1)• Sensor interrupt

– Time depends on speed– Average of 8 speed measurements– Digital filtering capability of the Timer S is used for proper

measurements Performance of filter

0

2000

4000

6000

8000

10000

12000

14000

0 10 20 30 40 50 60

Time in units of T period

Cou

nts

div 64div 32div 32div 16

Sensor Processing (2)• Sensor measurement time = 3.7 μs• Closed loop control time = 2 μs• CPU bandwidth is speed dependent

– For example, at 100 Hz speed, it is 100 times per second

Sensor data processing Control function

CPU Bandwidth Analysis

• Interrupt Time ~ 15 μs (@16kHz freq)• Timer S measurement = 3.7 μs • Closed loop control = 2 ms (4 μs) • CPU usage time in 1 second

– 15 * 16000 = 240000 μs – This time is required for sure– This is the main time as shown below

Speed RPM

Speed Hz

Timer S time μs

Closed loop time μs

Total ms

6000 100 370 400 240770 μs or ~0.25 second

12000 200 760 800 241560 μs or ~0.25 second

18000 300 1130 1200 242330 μs or ~0.25 second

Questions & Answers

• For a short period

Control Example V/f - Control

• open loop V/f control

– sensorless• induction machine• fan• M16C, H8, R8C,

SH

• closed loop V/f control – Tach sensor– Encoder

• compressor, pump

• M16C, H8, R8C, SH

MPWMsin(wt)

wset

patternwset t

wset A

sin(wt)MPWM

pattern

PI

-

w

Vector Control with a Rotor Position Sensor

Iq*

Vqc*

Id* Vdc*

VoltageCalculation

dq

3ΦPWM

inverter

dq3Φ

P2

θd

vu*,vv

*,vw*

6

Idc

Iqc

ω1

ACR ++Idc

+

-

ACR

Iqc

+-

Speed commandωr

*

ASR+-

++

ωrIu

Iw

Motor

input capture/

counter

Rotor positionθd

Rotating speed ωr

A,B,Z

Position SensorEncoder

Current Sensor(DCCT)

ACR - Auto Current RegulatorASR - Auto Speed Regulator PI Controller

Id*

ω

Iq*

Vqc*

Id* Vdc*

VoltageCalculation

dq

3ΦPWM

inverter

dq3Φ

P2

θdｃ

vu*,vv

*,vw*

6

Idc

Iqc

ω1

ACR ++Idc

+

-

ACR

Iqc

+-

Speed commandωr

*ASR

+-

++

ωrIuIw

Motor

Position &Speed

Estimator

Estimatedposition θdc

Estimated speed ωr

Current sensor(DCCT)

IuIw

Vu

Vw

PositionSensor-less

× Gain adjustment is very difficult.(ASR, ACR×2，Estimator(several parameters)）

Modern control theory・Observer・Kalman filter

↓Requires

Matrix Calculations

Vector Control with two DCCT

Id*

ω

OSCD vector control OSCD vector control

Iq*

Vqc*

Id* Vdc*

VoltageCalculation

dq

3ΦPWM

inverter

dq3Φ

P2

θdｃ

vu*,vv

*,vw*

6

Idc

Iqc

ω1

ACR ++Idc

+

-

ACR

Iqc

+-

Speed commandωr

*

ASR+-

++

ωrIuIw

Motor

Position &Speed

Estimator

Estimatedposition θdc

Estimated speed ωr

Shunt Resistance

IuIw

Vu

Vw

× Gain adjustment is difficult.(ASR, ACR×2，Estimator(several parameters)）

Modern Control Theory・Observer・Kalman filter

↓Requires

Matrix Calculations

Current Meas

PositionSensor-less

Vector Control with OSCD

Id*

ω

Current / Flux-Control Examples

• Closed loop speed control– Hall/encoder sensor or

sensorless pos. feedback

– current sensor• Brushless DC• Washing machine,

general purpose drives• H8S and SH devices

• Feed forward flux control / vector control

– Sensor or sensorless• Induction machine (IM)• Industrial tools• SH devices

PI

I

Pattern

PI

ω

sin(ωt)

ωt

PWM Mωset

ω

iset iabcset

i

uabcsetPI PI

sin(ωSt)

ωSt

PWM Mωset

ω

iYset iabcset

ω

iabcuabcset

iYsetim TR

im

im

ω

ωS

ωRiYset : Torque commandωS : stator frequencyωR : rotor frequency, (slip)im : magnet. currentTR : rotor time const.

+

1 SHUNT ELECTRICAL CURRENT MEASURING FUNCTION1 SHUNT ELECTRICAL CURRENT MEASURING FUNCTION

U phase

V phase

W phase

CarrierWave

TB2underflow

AN0

AN1

S/H and A-D conversion timing

1) TB0 and TB1 are started in one-shot modewith TB2 underflow as the trigger.

2) S/H or A-D conversions are executed with TB0 and TB1 one-shot trigger.

TB0 one-shot timer

TB1 one-shot timer

PRELIMINARYNotice This is not a final specification. Some parametric limits are Subject to change.

• OSCD method

Summary

• Induction motor fundamentals, motor construction, modulation techniques and control methods are covered in this presentation

THANK YOU ALL

renesas jani seminar 2

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