Letter Paper © 2012 ACEEE DOI: 01.IJRTET.07.2. Int. J. on Recent Trends in Engineering and Technology, Vol. 7, No. 2, March 2012 517 Performance Comparison of PID and Fuzzy Control Techniques in Three Phase Induction Motor Control T. D. Dongale 1 , S. R. Jadhav 2 , S.V. Kulkarni 3 , T. G. Kulkarni 4 , R. R. Mudholkar 5 , M. D. Uplane 6 1-4 Email: {tukaram.eln, eln.sjdhav, svkulkarni19, tushar.kulkarni19}@gmail.com 5,6 {rrm_eln, sensor}@unishivaji.ac.in Department of Electronics, Shivaji University, Kolhapur, India Abstract- The demand for control of electric power for electric motor drive system and industrial control exists since many years. Variable-speed drives are designed when a motor is combined with a power electronics converter. By introducing variable speed for the driven load, it is possible to optimize the efficiency of the entire system and this is the area where the maximum efficiency gains are possible. The closed loop control strategies employed are legion and PID is seemed to be superior amongst them. However it further needs to be improved in terms of overshoot and settling time. So control strategies based on soft computing could be good alternative. This paper describes the implementation of controllers based on PID and Fuzzy Logic strategies. A comparative performance analysis demonstrates that the clever exploring of Fuzzy Logic control strategies circumvents the demerits of PID control strategies. Index Terms— PID, Fuzzy Controller, Simulink Model, Three phase inverter, Induction motor I. INTRODUCTION AC motors are more popular with their integration in large number of applications like pumps, conveyors, machine tools, centrifugal machines, presses, elevators, and packaging equipment etc. The major benefits of using AC motor in a system are improved reliability, better performance, higher efficiency, easy scalability and feasibility of speed and torque control by different techniques. The techniques such as Rotor Resistance Control, Stator Voltage Control, Variable f, V/F Control, Slip Energy Recovery Scheme etc. play significant role in precisely controlling the speed of motors. Many re- searchers have reported the work on speed control of AC machines employing different control strategies [1-3]. The performance comparison of various drives reported in litera- ture help the comprehensive understanding the drive option targeted for application of interest [5, 11, 13]. An induction motor supplied by an ac drive can operate over a good range of frequency, typically from 10Hz to 90Hz. This range of fre- quencies yields rotor speeds from zero rpm to the rated value. The ac drive can produce the rated torque at any frequency within this range from zero to the rated frequency. Some ad- vanced techniques are practiced in motor control applica- tions. Among these PID is most popular Algorithm. Some researchers have used Fuzzy, Fuzzy-PID and Neuro Fuzzy techniques in their applications. In the present work the three phase motor drive is proposed implemented using PIC microcontroller. II. SYSTEM BLOCK DIAGRAM Figure 1. System Block Diagram The system block diagram is shown in fig.1. It is designed around PIC 16F877A. It includes inverter design, gate drive circuit, isolation and microcontroller. For the operation of variable frequency bridge inverter the required logic pulses are generated by using PIC microcontroller and are applied to gate drive circuit. The frequency for operation is read by microcontroller through Hall Effect speed sensor and current speed is sent to Simulink of PID or Fuzzy control technique through USART terminal of microcontroller. The gate drive circuit consists of opto-isolator provides isolation for microcontroller form the gate drive circuitry. The basic three phase voltage source inverter consists of six power MOSFETs with built in anti parallel diodes for freewheeling action. The IRFP-460 N- MOSFET operates as a switch. AC voltage from the power grid is rectified filtered and applied to three phase inverter as DC source. Power supplied to the motor is modulated by frequency generated by microcontroller. The speed sensed by Hall Effect sensor is displaying LCD [10]. A. Three Phase Inverter Design Three phase inverter designed using power MOSFETs is as shown in fig.2. The inverse diode associated with the device is sufficient to operate the circuit at higher frequencies. MOSFET technology promises to use much simpler and efficient drive circuits with significant cost benefits compared to bipolar devices. High voltage capacitor is connected across the rectifier out to provide low impedance path for high frequency current at switching of power devices.