Lecture - Speed Control of Induction Motor Part - 1 Video
Lecture - Speed Control of Induction Motor Part-2 Video
Implementing Embedded Speed Control for AC Induction Motors
Topices
•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
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
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Speed control of three phase AC induction motor using single phase supply along with active power factor correction
Abstract
Majority of industrial drives use electric motors, since
they are controllable and readily available. In practice,
most of these drives are based on ac induction motor
because these motors are rugged, reliable, and relatively
inexpensive. The proposed technique of single phase to
three phase conversion has a wide range of applications in
rural areas and also in industries where three phase
equipment or motors are to be operated from the easily
available single phase supply. These converters are
excellent choice for situations where three phase power
supply is not available. The added advantage is that the
three phase motor is more efficient and economical than
the single phase motor. Also the starting current in three
phase motor is less severe than in single phase motor.
This needs a strong, efficient cost effective and high
quality single phase to three phase conversion. Advanced
PWM techniques are employed to guarantee high quality
output voltage with reduced harmonics and sinusoidal
input current irrespective of the load. To obtain sinusoidal
input current at the terminal of single phase source a high
performance active input power factor correction
technique for single phase boost switch mode rectifier
operating with discontinuous current conduction is used.
The operation is based on variable turn-on time. Equal
Area Criteria (EAC) is applied to the discontinuous
current operation. To obtain high quality output voltage,
double edge modulated sine wave PWM technique is
implemented for three phase inverter. From experimental
results obtained on a laboratory prototype it can be
concluded that input power factor remains nearly unity for
any variations in the load or speed. Thus three phase ac
drives using single phase supply with improved power
factor is an approach to implement high frequency
induction boosting along with the three phase PWM
inverter for controlling the speed of three phase induction
motor by maintaining v/f ratio at constant value. This
scheme can be used in lathe machines, small cranes, lifts
etc, which are frequently switched ON and OFF1.
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