CONTROL OF SINGLE PHASEVOLTAGE CONVERTERS

In most power electronic applications, the power input is of 50 or 60 hertz AC voltage provided by the electric utility. It further converted to a DC voltage for various applications. The inexpensive rectifiers with diodes convert AC to DC and the output voltage is uncontrolled. The controlled rectifiers are used for providing variable/ constant output voltage. The dc output voltage of a controlled/uncontrolled rectifier should be ripple free. Therefore a large capacitor is connected as a filter on dc side. Due to this, controlled/uncontrolled rectifier has the following drawbacks; these rectifiers draw highly distorted current from the Utility and Power factor is very low. To take the edge off these drawbacks, High performance rectifiers are proposed in this paper. One of the authors has proposed a digital controller-based predictive instantaneous current control scheme for the single-phase voltage-fed rectifier and its modified analogue version. Although the control schemes obtain a sufficient performance, further simplification is necessary to realize an economical PFC converter system in practice. In this paper propose a simplified analogue controller-based predictive instantaneous current control scheme for single-phase voltage fed PFC converters, which is obtained from further modification of the original digital scheme. Since three phase converters have phase interference, a particular arrangement of the controller modulator for the three phase system is employed to avoid such phase interference. As a result, a simple predictive instantaneous current control scheme for three-phase voltage-fed PFC converters is obtained. In this paper, the predictive control methods for PFC are reviewed and their system configuration is highlighted in section II. The principles of the predictive control algorithm are discussed in same section. . In section III, the simulation results are presented. The conclusion is drawn in the last section.

CONFIGURATIONS:

A. Classification of different Topology

    Improved power quality converters are classified on the basis of topology and type of converter used. The topology-based classification is categorized on the basis of boost, buck, buck–boost, multilevel, unidirectional and bidirectional voltage, current, and power flow. The converter type can be step-up and step-down choppers, voltage source and current-source inverters, bridge structure, etc. These converters are developed in such vastly varying configurations to fulfill the very close and exact requirement in variety of applications. Some of these improved Power quality converters are improved to provide better performance from primitive configurations.

B. Current Control Techniques for PFC converters

      The current control techniques have gained importance in ac to dc converters used for high performance applications. Where the fast response and high accuracy are important. Various current control methods have been proposed and classified as hysteresis control, predictive control and linear control.