ABSTRACT

DC motor is widely used in industries due to its varieties and self-regulating speed. A high value of the armature current flows, when DC motor is directly connected to a DC voltage source. This high value of armature current is due to the lack of the Back Electromotive Force (emf) of the motor. The emf is known to be proportional to the motor speed. This high value of the armature current creates different problems to the DC motor in the shape of reduction of its lifetime and secondary by creation of false operation of the protective devices associated with the motor.
The classical method to mitigate such problem is to insert a starting resistor in series with the motor armature circuit. In this regard starting resistor should be gradually removed as the motor speeds up. A careful glance at such method exhibits that either it controls or monitor the level of the armature current, it also be demonstrate the wastage of energy at each start-up maneuver.
This work proposes the solution of the above drawback in two ways by the use of (i) A chopper circuit between the supply voltage and the motor armature circuit and (ii) A variable DC voltage source.
The simulation models of these types of Starters are developed with the help of Matlab/Simulink/Simp Ower Systems. First the applicability and the suitability of these proposed starters is compared and finally with conventional starter. The comparison of results shows that the electronic starter is better than conventional starter due to its fast speed and less energy wastage. There is less harmonic distortion if thyristor is used in place of MOSFET, also the armature current does not exceeds100 Amperes.