An Active Power Factor Correction Technique for Bridgeless Boost AC-DC Converter

Abstract

As most of the electronic appliances use DC power so improvement in AC-DC converter is always at large by the researchers. The factors of improvement of power quality are reduction in total harmonic distortion and improvement in power factor at input ac, and tight output dc regulation. In such context, the AC-DC boost converters have gained significant importance, especially when they are used in Continuous Conduction Mode (CCM). This work presents a bridgeless AC DC boost converter operating in CCM. The implementation of input current and output voltage controller is also discussed. Then a comparative analysis based on simulation results of bridgeless and bridge boost rectifier is presented. Bridgeless boost AC-DC converter has outperformed the conventional techniques due to lower conduction losses, lower THD of input current and improved input power factor. I. INTRODUCTIONRectification is a process in which electric power is applications as most of electronics appliances nowadays require DC power. Conventional AC-DC converters, such as Bridge rectifiers, have been developed for this purpose but there are few factors to be controlled in this regard. The Non sinusoidal current drawn at the input side results in lower distortion as well displacement factors. Commanding the line current to follow the line voltage in a sinusoidal manner can gives higher efficiency with improved power factor and lower THD. AC side power factor (PF) is needed to be improved along with lowering of Total Harmonic Distortion of input line current. Tight regulation of the output voltage even in the case of dynamic loads is also a stringent requirement of DC-DC converters. A controller that simultaneously controls both the input as well as the output parameters is the choice. To gain a high power factor, different power factor correction (PFC) techniques have been introduced which can be divided into two parts, passive and active. Passive techniques consist of passive components such as inductors and capacitors that are used as input filter to reduce line current harmonics. However, improvements are not significant and another drawback is the relatively large size of these passive elements. Moreover, these techniques may not be able to handle dynamic loads. On the other hand, active PFC technique is more efficient solution, having a combination of switches and passive elements. Due to presence of switches, controllers can be implemented on active techniques of PFC. At the cost of complexity, the controlled active techniques can increase Power factor and reduce THD in the input AC current. Along with it active techniques can also bring precise DC regulation for variable loads. The active PFC technique uses a diode bridge rectifier followed by a dc-dc converter and the bulk capacitor. By controlling the dc-dc converter, the input line current is commanded to follow the input line voltage and in this way Power Factor approaches to unity. For medium and high power applications boost dc-dc converter works better for power factor corr...