An alternate soft starter for DC motors

This paper investigates the performance of an alternate power electronic circuitry that can be used in starting DC motors. The proposed circuit differs from the various methods that are often used to regulate the machine armature current during startup. Note that such methods include the use of a variable resistance between the armature circuit and the supply DC voltage, or implementing a control system that limits inrush current in power electronics circuits. This paper explores a precise, cost-effective technique by utilizing H-bridge circuitry between the armature circuit and the supply DC voltage. A microcontroller responds to armaure current sensor readings in controlling four MOSFET's gate pulses of the H-bridge circuit while targeting a soft start objective. Quite satisfactory simulation and practical results were reached.