COMPARATIVE ANALYSIS OF CONTROL OF AC TO DC CONVERTERS

Abstract

Pulse width-modulated (PWM) rectifier technology is increasingly used in industrial applications like variable-speed motor drives, since it offers several desired features such as sinusoidal input currents, controllable power factor, bidirectional power flow and high quality DC output voltage. To achieve these features, however, an effective control system with fast and accurate current and DC voltage responses is required. From various control strategies proposed to meet these control objectives, in most cases the commonly known principle of the synchronous-frame current vector control along with some space-vector PWM scheme have been applied. Power factor corrected boost rectifier four-wire method scheme have been eliminated harmonic in current through neutral line Recently, however, new control approaches analogous to the well-established direct torque control (DTC) method for electrical machines have also emerged to implement a high performance PWM rectifier. This thesis aims at the comparative analysis of various PWM control strategies for AC-to DC converters Four-Wire Average Current control, Space Vector modulation, Direct Power Control Method, Virtual Flux direct Power Control Method is implement that algorithm in the converter and apply various load conditions. Simulation models are developed in MATLAB for different control strategies to compare the results and obtain a performance evaluation. The performance of an AC-to-DC converter controlled by each control strategy has been evaluated under various conditions by varying the load for input current, THD, power factor and efficiency, dynamic mode and regenerative mode. The performance parameters are calculated for all the converters and then compared with each other, and compare the change load conditions.