Comparative Simulative Study of Power Factor Improvement by Employing Extinction Angle Control in AC-AC Voltage Converter

Author Name(s): Komal Ambhorkar, Piyush Khadke, Dhananjay Tutakne
Author Email: komal.ambhorkar14@gmail.com

Abstract

The paper deals with comparative analysis of proposed single phase induction motor (SPIM) drive with Extinction Angle Control (EAC) technique and conventional TRIAC controller with Phase Angle Control (PAC) technique motor for fan load application. The important feature of presented scheme is leading and high power factor with smooth control. In this paper, the performance evaluation of presented scheme with EAC and conventional scheme with PAC has been illustrated in MATLAB Simulink for Static RL load. The simulated waveform of load voltage, load current, input voltage and input current for SPIM drive is also presented.

Introduction

Single phase induction motor has been widely used for fan, blower load applications in various industries and also for low power residential applications. The control technique used for speed control of SPIM for such application is phase angle control technique with TRIAC as controllable switch. [1]-[3] However they have some disadvantages as low input power factor at large firing angle, lower efficiency and temperature rise in motor. The power flow is also discontinuous at both input and output side with PAC technique.[4] Moreover the efficiency of motor at light load is quite inefficient since the phase angle between stator voltage and stator current is lagging which makes power factor poor. [5] The present paper introduces a simple scheme to get direct AC to AC voltage for smooth speed control of induction motor with improved input power factor. The disadvantages discussed above with PAC technique can be overcome by employing EAC technique to the proposed scheme. The presented scheme consist of main switch which controls the speed of induction motor and freewheeling switch to freewheel the motor current when main switch is OFF. The speed of induction motor can be control by varying the duty ratio of main switch while during turnoff of switch, the circulation of current through the motor is maintained in same direction using freewheeling switch. [6] The switching technique used to drive motor is such that the motor draws leading and high power factor current in entire controllable speed range.

Conclusion

Comparative study of two techniques i.e. EAC and PAC for SPIM drive has been presented in this paper. The EAC technique was found to be better for input power factor improvement. It not only improves the supply power factor from load power factor but also it becomes leading as extinction angle exceeds load angle. The PAC technique applied to TRIAC controller is superior from input current THD point of view and provides better results than proposed technique

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