03-09-2014, 12:36 PM
INDUCTION MOTOR
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Abstract:
This study presents the design of high performance PID controller for three phase induction motor V/f
speed control with induction motor mathematical modeling. V/f method is a simple method for speed control of
induction motor. The control scheme is based on the popular constant volts per hertz (V/f) method using the high
performance PID controller. Design of induction motor mathematical modeling and PID controller for Space Vector
Pulse Width Modulation inverter are proposed for induction motor V/f speed control. The simulation is carried out
by MATLAB/Simulink.
INTRODUCTION
Three-phase induction motors are the most
common and frequently encountered machines in
industry. Because it has Simple design, high power to
weight ratio and easy to maintain. V/f control of
induction motor has large applications in industry. The
control strategy consists of keeping constant
the voltage-frequency ratio of the induction motor
supply source. Subhankar et al. (2012) discussed about
PID controller based closed loop system which makes a
squirrel cage induction motor running under constant
volt/hertz ratio. In this study motor is modeled
according to the transfer function based on inductance
matrices or L-matrices of the motor. The motor exhibits
to run in the user defined or command speed.
Dazhi et al. (2004) discussed about a neural
network adaptive PID controller for speed sensor less
field-oriented control of induction motor. By measuring
the phase voltages and currents in Induction Motor (IM)
drive, the multi-step predictive control, neural networks
based rotor flux components and speed identification
method for IM are used. Ustun and Demirtas (2008)
analyzed about a new method of the optimal tuning of
proportional integral controller coefficients in the offline control of a induction motor. Uddin and Hao
(2007) discussed about Neuro fuzzy control for
induction motor .The main task of this tuning method is
to adjust the parameters of the Fuzzy Logic Controller
(FLC) in order to minimize the square of the error
between actual and reference outputs. Rodriguez et al.
(2009) discussed about Direct Torque Control (DTC)based on load angle control. The use of simple
equations to obtain the control algorithm makes it easier
to understand and implement. Fixed switching
frequency and low torque ripple are obtained using
space vector modulation.
In this study, therefore, proposes a high
performance PID controller for three phase induction
motor V/f speed control. The complete mathematical
model of three phase induction motor also carried out.
MATHEMATICAL MODELING OF
INDUCTION MOTOR
In the control of any power electronics drive
system to start with a mathematical model of the plant
is required. To design any type of controller to control
the process of the plant mathematical model is required.
Lashok et al. (2009) have analyzed about the
mathematical modeling of induction motor, the power
circuit of the 3-φ induction motor is shown in the
Fig. 1
Space Vector Pulse Width Modulation (SVPWM)
is an optimum pulse width modulation technique for an
inverter used in a variable frequency drive applications.
It is computationally rigorous and hence limits the
inverter switching frequency. Senthilkumar and Vijayan
(2012) have designed PID controller for Space Vector
Pulse Width Modulation inverter for induction motor
V/f speed control without mathematical modeling. The
design of PID controller without mathematical
modeling is shown in Fig. 5. The design of PID
controller for Space Vector Pulse Width Modulation
inverter for induction motor V/f speed control with
mathematical modeling is shown in Fig. 6. A
Proportional-Integral-Derivative controller (PID
controller) is a generic control loop feedback
mechanism widely used in industrial control systems.
PID is the most commonly used feedback
controller. A PID controller calculates an "error" value
as the difference between a measured process variable
and a desired set point. The controller attempts to
minimize the error by adjusting the process control
inputs. PID controller module is shown in Fig. 7.
The Ziegler-Nichols tuning method is used to a
tune the PID controller. The proportional, integral and
derivative terms are summed to calculate the output of
the PID controller.
RESULTS AND DISCUSSION
Math mathematical modeling of induction motorparameters:Induction motor parameters are given in
Table 1.
PID controller simulation results:
The PID controller
for induction motor v/f control without mathematical
modeling simulation output for a Set speed of 1500 rpm
is shown in Fig. 8. X axis time in sec. Y axis speed in
rpm.
The PID controller simulation output for a Set
speed of 2000 rpm with induction motor mathematical
modeling is shown in Fig. 9. X axis time in sec. Y axis
speed in rpm.
According to the results, the PID controller with
induction motor mathematical modeling and without
modeling gives good response.
CONCLUSION
In this study we proposed mathematical modeling
of three phase induction motor. We analyzed the V\f
control speed response of three phase induction motor
with mathematical modeling. This system can be
extended with other advanced soft computing
techniques. This induction motor modeling can be
further used to design advanced controllers for
induction motor speed control.