Introduction of AC DriveIntroduction of AC Drive

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Presented By:Application DepartmentLubi Electronics

DC MotorDC MotorDC Motor

Advantages:Advantages:--

1.1. To control the motorTo control the motors s armature voltage high and armature voltage high and low for get different low for get different

frequency output.frequency output.2.2. The Output Torque is The Output Torque is

proportion to the Armature proportion to the Armature

current.current.

Disadvantages:Disadvantages:--

1.1. Use carbon brush and rectifier to Use carbon brush and rectifier to make armature magnetic filed make armature magnetic filed and rotor current with a and rotor current with a 9090.Therefore, motor can output .Therefore, motor can output a constant torque. But, the a constant torque. But, the carbon brush and rectifier are carbon brush and rectifier are both machinery, they will result both machinery, they will result a spark and damage when the a spark and damage when the motor is rotating.motor is rotating.

Induction Motor principleInduction Motor principle

33--phase voltage phase voltage Stator rotated currentStator rotated current

Stator rotated current Stator rotated current Stator rotated magnetic flux Stator rotated magnetic flux

Stator rotated magnetic flux Stator rotated magnetic flux Rotor inducted voltageRotor inducted voltage

Rotor inducted voltage Rotor inducted voltage Rotator currentRotator current

Stator magnetic flux and Rotor current product TorqueStator magnetic flux and Rotor current product Torque

Motor TorqueMotor Torque

Stator magnetic field rotated and drive Rotor magnetic field whiStator magnetic field rotated and drive Rotor magnetic field which ch just like 2 magnet are pursued each other just like 2 magnet are pursued each other

S NNS

BsBr

2,4,6 pole motor stator magnetic field2,4,6 pole motor stator magnetic field

R.P.M.= Frequency*120/Pole

RPM=fre*30

S

NS

N

RPM=Fre*60

S N

RPM=fre*20

NS

N S

S N

What is AC MOTOR Drive ?What is AC MOTOR Drive ?

Input a AC1Input a AC1 or 3or 3power source, convert it to become DC Source power source, convert it to become DC Source (via Converter). After, using the Inverter part to become a (via Converter). After, using the Inverter part to become a Variable Variable Voltage Variable FrequencyVoltage Variable Frequency 3 3 AC power source.AC power source.

Using this power source to control a Induction motorUsing this power source to control a Induction motors speed and s speed and Torque.Torque.

Once, the frequency command has been modified, the output Once, the frequency command has been modified, the output voltage will also be changed. Therefore, the AC motor drive callvoltage will also be changed. Therefore, the AC motor drive called ed for short as for short as VVVF VVVF (Variable Voltage Variable Frequency)(Variable Voltage Variable Frequency)

Why do we need InverterWhy do we need Inverter

Motor: Transforms electricity into mechanical energyMotor: Transforms electricity into mechanical energy

Motor application: NC machine, manufacture line, Lift, Elevator Motor application: NC machine, manufacture line, Lift, Elevator door, Textile industrial, Water supply systemdoor, Textile industrial, Water supply systemetcetc

Motor job: To drive machine for Acceleration, operating speed, Motor job: To drive machine for Acceleration, operating speed, DecelerationDecelerationetc motion or position controletc motion or position control

Drive: To achieve above motion with high performance Drive: To achieve above motion with high performance

AC Motor Drives FeatureAC Motor Drives Feature

FeaturesFeatures Controlling variables are Voltage & FrequencyControlling variables are Voltage & Frequency Simulation of variable AC sine wave usingSimulation of variable AC sine wave using

modulatormodulator Flux provided with constant Flux provided with constant v/fv/f ratioratio OpenOpen--loop driveloop drive

Both frequency & voltage references are fed into a modulatorBoth frequency & voltage references are fed into a modulatorwhich simulates an AC sine wave & feeds this to the motorwhich simulates an AC sine wave & feeds this to the motorssstator winding. This technique is called Pulse Width stator winding. This technique is called Pulse Width modulation (PWM). The inverter control the motor in the modulation (PWM). The inverter control the motor in the form of a PWM pulse train dictating both the voltage & the form of a PWM pulse train dictating both the voltage & the frequency.frequency.

Significantly, this method does not use a feedback deviceSignificantly, this method does not use a feedback devicewhich takes speed or position measurements from the which takes speed or position measurements from the motormotor shaft & feeds these back into the control loop.shaft & feeds these back into the control loop.

ADVANTAGE ADVANTAGE

CloseClose--loop / open loop facilities.loop / open loop facilities. Motor protection like Over voltage, Over current, Phase lose, OvMotor protection like Over voltage, Over current, Phase lose, Over er

load, Over Heat etc.load, Over Heat etc. Easy controlling of motor.Easy controlling of motor. Soft startSoft start Energy SavingEnergy Saving Controlled outputControlled output Maximum torque at low speedMaximum torque at low speed Remote Operating systemRemote Operating system Digital display shows like Amp, Hz, RPM.Digital display shows like Amp, Hz, RPM.

Currently AvailableCurrently Available

V/HzV/Hz

Open Loop Vector or Open Loop Vector or SensorlessSensorless VectorVector

Closed Loop Vector or Flux VectorClosed Loop Vector or Flux Vector

NoteNote: All the above utilize : All the above utilize IGBTIGBTss (For Power) & PWM switching (For Power) & PWM switching method (For Control)method (For Control)

V/HzV/Hz

Generically called Generically called vvvfvvvf or Variable Voltage Variable Frequency or Variable Voltage Variable Frequency control modecontrol mode

Attempts to improve low speed torque performance by means of Attempts to improve low speed torque performance by means of Fixed Voltage Boosting available in the driveFixed Voltage Boosting available in the drive

Relies on engineerRelies on engineers competence & experience on each application s competence & experience on each application --THE HUMAN ANGLE!!THE HUMAN ANGLE!!

Any improvements?Any improvements?

Open Loop Vector mode....Open Loop Vector mode....

Using the advantages of microUsing the advantages of micro--processors, this improves upon the processors, this improves upon the v/fv/f mode by :mode by :

Mathematical Mathematical modellingmodelling of motor for getting a measure of the of motor for getting a measure of the

magnetizing componentmagnetizing component

Open Loop VectorOpen Loop Vector

Boost at low speeds is machine Boost at low speeds is machine -- specificspecific

Definite improvement on the N Definite improvement on the N v/sv/s T characteristics....T characteristics....

.....But still an approximation!!.....But still an approximation!!

Finally the name Finally the name -- Open Loop since measurement is still indirect!Open Loop since measurement is still indirect!

So whatSo whats next??s next??

Closed Loop Flux Vector Closed Loop Flux Vector -- The exact wayThe exact way

Uses a measurement device physically attached to the motor NDE, Uses a measurement device physically attached to the motor NDE, typically an encoder with Marker pulsetypically an encoder with Marker pulse

AimAim: Check Rotor Shaft orientation at all instants!: Check Rotor Shaft orientation at all instants!

Flux Vector???Flux Vector???

FluxFlux : Idea is to calculate Stator Field distribution by means of : Idea is to calculate Stator Field distribution by means of measuring rotor orientation measuring rotor orientation at all instantsat all instants!!!!

VectorVector : Since both direction & magnitude can be controlled : Since both direction & magnitude can be controlled simultaneouslysimultaneously

The Net GainThe Net Gain

Gives you the luxury of full torque right down to zero speed Gives you the luxury of full torque right down to zero speed (Hold/Standstill / Stall Tension events)(Hold/Standstill / Stall Tension events)

The Vital differenceThe Vital difference

v/fv/f & OL Vector confer control advantages due to low speed torque & OL Vector confer control advantages due to low speed torque correction thru APPROXIMATION ONLYcorrection thru APPROXIMATION ONLY

Flux Vector mode gets you an instantaneous current (stator) Flux Vector mode gets you an instantaneous current (stator) distribution pattern as necessary to produce required set torquedistribution pattern as necessary to produce required set torque --The EXACT wayThe EXACT way

DC MotorInduction Motor principleMotor Torque2,4,6 pole motor stator magnetic fieldWhat is AC MOTOR Drive ?Why do we need InverterAC Motor Drives FeatureSignificantly, this method does not use a feedback devicewhich takes speed or position measurements from the motor shaft & Currently AvailableV/HzAny improvements?Open Loop VectorSo whats next??Flux Vector???The Net GainThe Vital difference