FPGA-based Real-time Performance Analysis of Buck-regulator Fed Current Source Inverter

Abstract

This paper presents an advanced buck-regulator fed current source inverter and the performance analysis of the same is compared with conventional voltage source inverter (VSI) and current source inverter (CSI). In many applications such as brushless dc motors and stepper motors, a square or modified square wave ripple free current for certain period of time is required. However, with pulse width modulation (PWM) voltages and currents obtained at the output of conventional VSI and CSI contains harmonics. A buck-regulator fed CSI is capable of minimizing the voltage and current ripples even if PWM technique is employed. Hence, the harmonic distortion analysis for both load current and voltage delivered by VSI, CSI and buck-regulator fed CSI are performed in this paper. The analyses are performed with traditional 120° conduction and with multiple carriers based PWM approach. Presently buck-regulator fed CSI has been widely implemented in special motor drives applications. The compared converters are validated with a fixed RL load both in simulation as well as a prototype developed in the laboratory. Results shows that with the use of an inductor with reduced number of turns, the ripples in the output current for the buck-regulator fed CSI is minimized significantly compared to a conventional CSI and hence load side filter can be avoided.