A robust 6 kW variable DC power supply with closed loop control system

Abstract

In this paper, a development of a 6 kW variable DC power supply hardware implementation is presented. The power supply design is based on switched mode power supplies technology. This power supply provides variable output voltages of 10, 20, 30, 40, 50, and 60 V. Effective low cost techniques were employed. The power supply circuit is composed of three main circuits; the input power conversion circuit, the Buck converter power circuit that is controlled by a PWM signal, and the control circuit which includes the logic, isolation and driving circuits. A switching technique is employed based on duty cycle control by which the different outputs are obtained. An insulated gate bipolar transistor (IGBT) is used as a power switch protected by a snubber circuit. A negative feedback is employed to maintain constant output. The snubber circuit is used to dissipate the switching losses and to protect the IGBT switch. A heat sink is used, based on the thermal calculations carried out. The required outputs are obtained by varying the duty cycle and the waveforms at the source are displayed with respect to the switching gate signal. A frequency domain analysis is carried out to show the relative stability of this scheme.