Uthen Kamnarn

Analysis and Design of a Modular Three-Phase AC-to-DC Converter Using CUK Rectifier Module With Nearly Unity Power Factor and Fast Dynamic Response

In this paper, the analysis and design of a modular three-phase AC-to-DC converter using single-phase isolated Cuk rectifier modules is discussed based on power balance control technique. This paper analyzes the operation of a modular converter as continuous-conduction-mode power factor correction (CCM-PFC). Design equations, as well as an average small-signal model of the proposed system to aid the control loop design are derived. It is used to obtain the inductor current compensator, thus the output impedance and audio susceptibility become zero, and therefore, the output voltage of the converter presented in this paper is independent of the variations of the dc load current and the utility voltage. The control strategy consists of a single output voltage loop and three-inductor current calculator. The main objective of the proposed system is to reduce the number of stages and improve dynamic response of DC bus voltage for distributed power system. The proposed scheme offers simple control strategy, flexibility in three-phase delta or star-connected, simpler design, fast transient response, good inductor current sharing, and power factor closed to unity. Both simulation and experimental results are presented. They are in agreement with the theoretical analysis and experimental work.

Redundant three-phase AC to DC converter using single-phase CUK rectifier module with minimized DC bus capacitance

This paper presents a redundant three-phase ac to dc converter using single-phase CUK rectifier module with nearly power factor and minimized dc bus capacitance based on power balance control technique. The focus of the proposed control strategy is to reduce the dc bus capacitance value under condition step load change from 10% (75W) to 100% (750W). Using power balance control technique does minimized dc bus capacitance, inductor current sharing, redundant operation, high power factor and tight dc bus voltage works on the principle of modular three-phase rectifier with parallel single-phase CUK rectifier module. Simulation results are used to illustrate the operation and performance features of the modular three-phase rectifiers.

Three-Phase AC to DC Converter with Minimized DC Bus Capacitor and Fast Dynamic Response

The analysis and design of a nearly unity power-factor and fast dynamic response of the modular three-phase AC to DC converter with minimized DC bus capacitor is discussed. The proposed system significantly improves the dynamic response of the converter to load steps with minimized DC bus capacitor. It chooses output capacitor according to the output voltage droop and overshoot. This is confirmed by 600 W prototype modular three-phase AC to DC converter comprising three 200 W single-phase SEPIC rectifier modules with dc bus output capacitor 470 muF and experimental implementation.

Implementation of distributed control for parallel AC/DC converters

The distributed control method of parallel-connected AC/DC converters is presented. The paper describes the mathematical model of the proposed system to design the output voltage control. For the flexibility and modularity purpose, each converter module employs an individual microcontroller to control the power converter operation and communicate among other converter modules for sharing a load current. The experiment is conducted by a three-250 W/module isolated CUK power factor correction (PFC) circuit. From the experimental results achieve as the following: the output voltage regulation and the current sharing is quite good, a high power factor, and simple for implementation.

Distributed control of parallel AC to DC converter

This paper presents the distributed control of parallel AC to DC converter using power balance control technique. Three single-phase CUK converters based on power factor correction (PFC) are parallel connected at dc outputs. Each converter operates in continuous conduction mode. The control systems consist of the voltage loop control and hysteresis control techniques apply to the current loop control. The microcontroller is used to communication between each controller of each module for adaptive power balance technique. The simulation results, three of 250 W/module are as follows : the inductor current sharing equally, fast transient response, tight dc bus voltage regulation, system modularity, redundancy and high power factor. So, the simulation results are used to illustrate the operation and investigation of the distributed control technique.

A low-cost microcontroller-based maximum power point tracking system with multiple-string connection for PV stand-alone applications

The aim of this paper is to design and implementation of a multiple-string connection using modular buck converter with Maximum Power Point Tracking (MPPT) for stand-alone PV solar energy system. A simple, highly-performance algorithm suitable to be implemented in a low-cost microcontroller (PIC 18F4431) has been developed in order to make photovoltaic arrays track and operate in their maximum power point. A 3kWp prototype distributed solar controller comprising 4-modular MPPT buck converters with the proposed control scheme has been designed and implemented. Experimental results confirm excellent tracking effectiveness and rapid dynamic response.