Adaptive Slip Power Recovery System in Three Phase Slip Ring Induction Motor with Synchronous Speed

Adaptive Slip Power Recovery System in Three Phase Slip Ring Induction Motor with Synchronous Speed
Authors:RATANSINGH ATKAR, CHANDRAMOULI.B

Abstract: The research study takes a look at the impact slip rings power losses of three phase slip ring induction motor. The output slip power losses are more during speed control in two methods which we prefer in present days at Electrical industries and in Electrical Laboratory for speed control purpose. One is Doubly-fed method-The speed of the motor is controlled by three variable rheostat of same rating used at the end of output slip terminals of different phases. Second is converting AC slip power into DC-instead of mechanically varying the resistance, the equivalent resistance in the rotor resistance is definitely advantageous compared to Rheostatic controlled, but the problem of poor drive efficiency remains the same. To overcome these losses the 3rd method is designed named modified static Kramer drive system a bridge diode rectifier, a cyclo inverter and a step up transformer. The three phase out put frequency and voltage of synchronous power at slip could be stepped up and converted as same input voltage and frequency. This synchronous power is now fed into main supply to the motor. And motor speed could be controlled by using inverter and the problem of poor drive efficiency is increased. 

Keywords: Power Loss Due To Heat, Synchronous Power, Poor Drive Efficiency, Insulation, Cyclo Inverter Synchronous Frequency.

INTRODUCTION 

       This research study has the impact of the principle of slip power recovery drive particularly to reduce the power losses at output terminals of slip ring induction motor due to the output. Slip power losses are more during speed control due to use of variable resistance (Rheostat) in previous methods. Previous works include the two methods named as Doublyfed: Machine speed control by rotor rheostat in which when output slip terminals were connected to each other with any coil when the motor was at full load. The speed of the rotors was controlled by these variable rheostat of same ratting used at the end of output slip terminals of different phases And the second method is Speed control by converting ac into dc and varying a rheostat: instead of mechanically varying the resistance the equivalent resistance in the rotor circuit can be varied statically by using a diode bridge rectifier and chopper. This electronic control of rotor resistance is definitely advantageous compared to rheostatic control method, but the problem of poor drive efficiency remains the same. The contribution of this paper is to overcome the losses which occur in previous methods. The slip power or synchronous power is converted into dc by diode bridge rectifier and the DC voltage is converted into AC by line commutated inverter and fed back to supply. As the slip power can flow only in one direction, modified static Kramer drive offers speed control below synchronous speed only and improves overall poor drive efficiency of the system.

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