Bhim N. Singh

Voltage and frequency control with reduced switch integrated voltage source converter for IAG in wind energy conversion system

This paper deals with a voltage and frequency controller (VFC) of a stand-alone wind energy conversion system using an isolated asynchronous generator (IAG) feeding three-phase four-wire loads. The reference generator currents are estimated using the power balance theory to control the voltage and frequency of IAG system. Two-leg reduced switch integrated voltage source converter (VSC) with a battery energy storage system (BESS) is used as a VFC for the power management of the wind energy conversion system (WECS). The proposed VFC works as a voltage regulator, a load leveler, a load balancer and a harmonic eliminator in WECS. The wind power driven IAG system is modeled and simulated in the MATLAB using Simulink and sim power system (SPS) toolboxes.

DSP based control method of active filter: elimination of switching ripples

This paper deals with a DSP based implementation of a three-phase shunt active filter (AF) to compensate harmonics and reactive power of nonlinear loads. A three-phase diode bridge rectifier with R-L and R-C loads is taken as the nonlinear load. It is observed that the AF systems suffer from the problems of switching ripples and these ripples contribute considerably to the total harmonic distortion (THD) in the supply current. This investigation proposes a new, cost free and simple approach for the elimination of switching ripples. A PWM current controlled voltage source inverter (CC-VSI) is used as the AF. In current controlled VSI two types of PWM techniques, namely, carrierless (hysteresis) and carrier based techniques are used. Two types of current control techniques, namely, direct current control and indirect current control are designed to obtain PWM switching signals for the devices of the AF. A laboratory prototype model of an AF is tested with both the direct and indirect techniques. The capability of the indirect current control technique towards the elimination of switching ripples is established. Experimental results for steady state and transient operating conditions of the AF are given and discussed in detail.

Unity power factor converter-inverter fed vector controlled cage motor drive without mechanical speed sensor

This paper presents a comprehensive analysis of a vector controlled induction motor drive. The motor is fed from a current controlled converter-inverter system which acts as an ideal frequency changer and offers four quadrant operation. An intelligent and robust closed loop speed control of the cage induction motor drive is obtained using a fuzzy logic based sliding mode speed controller. The motor speed is estimated using a flux model based observer which uses terminal conditions of the motor and its parameters and it eliminates the use of a mechanical speed sensor. The simulated results reveal that the proposed drive system exhibits a high level of performance at input/output ports (AC mains and the motor) of the integrated converter-inverter link. The potential applications of this drive are identified.