vector control introoduction

7/28/2019 vector control introoduction

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Real-Time Simulation &

Vector Control ofInduction Motor/PMSM

for Hybrid Vehicles

Vikrant MoreAkshay Mhalgi

Akshat Khanna


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Induction Motor Speed Control

Scalar Control : The magnitudes of control variables arecontrolled, while the coupling effect is disregarded.

For example, the voltage of a machine can be controlled tocontrol the flux, frequency and slip can be controlled to

control torque. The various scalar methods employed are:

Stator Voltage Control.

Current control.

Volts/hertz control.

Rotor voltage control.


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Scalar control methods provide satisfactory steady stateperformance but poor dynamic response.

Vector Control : Both magnitude and phase of controlvariables are controlled. The aim of vector control is toget the response from a induction motor similar to thatof a separately excited DC motor.

The machine control is considered in a synchronouslyrotating reference frame.

Sinusoidal quantities appear as dc quantities in steadystate.

With vector control, ids is analogous to field current & iqsto armature current of a dc machine and areorthogonal.

Induction Motor Speed Control


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dqs

equivalent

circuit

diagram

(steady

state)

Steady state Phasor diagrams


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d-q Model

Vector control drives are based on the dynamicd-q model of the machine.

In dynamic model, coupling coefficients

between stator & rotor phases vary with rotorposition. Such an analysis is complex.

Using Parks transformation, we refer statorvariables to a synchronously rotating referenceframe fixed in the rotor thereby eliminatingvarying magnetic reluctances .

For vector control drives, we transform threephase stationary reference frame into two phasestationary frame and then transform these into arotating reference frame.


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Transformation from stationary reference frame to rotating reference frame


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Dynamic equivalent circuits of the

machine in synchronously rotating frame


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Vector Control Principle

Vector control implementationprinciple with machine deqe model


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Indirect Vector Control

In indirect vector controlmethod, the unit vector signalsare fed in feed forwardmanner.

The synchronously rotating axis

de-qe is rotating ahead of thedr-qraxis by positive slip anglecorresponding to slipfrequency.

we=wr+wsl. This gives us the

value of

e upon integration


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Required Motor

Characteristics

0

5

10

15

20

25

30

0 500 1000 1500 2000 2500 3000 3500 4000 4500

MotorPower(kW)

Motor Speed (rpm)

Electric Motor Characteristics

MotorCharacteristics


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Rotor winding of synchronous motors is replaced bypermanent magnets.

Advantages- Elimination of rotor Cu loss, higher powerdensity, low rotor inertia and robust construction.

Essentially two types based on construction-

Sinusoidal Surface Mounted PMSM

Sinusoidal Interior Mounted PMSM

Permanent Magnet Synchronous

Motors


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For application in hybrid vehicles, we need operation ofthe motor above base speed.

Both types of motor provide operation above basespeed, but the interior mounted PMSM provides a betteroperation above base speed and so it is preferred.

Cross section of a interior mounted PMSM is as shown--

Permanent Magnet Synchronous

Motors


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Operation in Field

Weakening Mode PMSM used is to be operated above its base speed.

In vector control of a PMSM, to get operation abovebase speed, we operate the motor in flux weakening

mode.

IPM PMSM provides a greater range of operation infiled weakening mode.


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THANK YOU

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vector control introoduction