This study presents a distributed control system for parallel-connected AC/DC converters. The proposed system composed of isolated CUK AC/DC converters which each converter has its own controller and a simple current-sharing circuit. The purposes are modular system and distributed control. The control system consists of an analogue circuit and a microcontroller. The analogue circuit is used for a current sharing and control the input current to be in-phase with the input voltage. The microcontroller is used for generating the control signals to adjust gain of the current sharing and to control the output voltage. The performance evaluation was conducted through the simulation and experimental results, on a threemodule parallel-connected, with a 540 W load, a − 48 V of DC bus output voltage. The performance of the proposed system has been achieved as follows: the current sharing is quite well; the redundant operation can be implemented in this system, the fast transient response and a high-power factor.
The analysis and design of a parallel AC to DC CUK converter circuit based on power balance control technique for DC Distributed Power System (DPS) applications are presented. The three parallel modules system with fast dynamic response using single voltage loop control and inductor current calculator for input current wave shaping, inductor current sharing and output voltage regulation, while keeping the power factor very close to unity have been shown. The experimental prototype have been built with a DC output voltage −48 V and output power 750 W. Fig. 1 shows the waveform of input voltage and current. Evidently, the line current is almost in phase with the input phase voltage and nearly sinusoidal. The input current total harmonic distortion (THD) is 3% at full load and 6% at half load. Figure 2 shows three individual inductor currents at step load change from 100% to 50%. Due to the effect of difference inductance values and parasitic in input inductors, these inductor currents are not exactly equal. Fig 3 shows inverted transient response of output voltage and load current with the ripple output voltage 3.2 V. It is indicated that the good dynamic performance can be achieved.The CUK PFC parallel scheme can provide good power factor from 200 W to full load. Both the power factor and THD i are insensitive to the line voltage. Therefore, CUK converters in CCM operation are suitable as power-factor-correction over a variation of input voltage. Experimental prototype with a total of 750 W output power for three power modules and common output −48 V@ −15.625 A is built toverify the concept presented. It has been shown that good output voltage regulation, input power factor correction and the inductor current sharing are achieved by controlling the duty-ratio for all modules. The proposed approach offers the following advantages: simple control and fast dynamic response. A high power factor (PF > 0.99) can still be achieved. A 750 W prototype modular converter system with 85% efficiency operating completely in the CCM has confirmed the analysis.-1 -
Paper
Analysis and Design of a Parallel CUK Power Factor Correction Circuit Based on Power Balance Control TechniqueUthen Kamnarn *
Non-memberViboon Chunkag *
Non-memberThe analysis and design of a parallel AC to DC CUK converter circuit based on power balance control technique for DC Distributed Power System (DPS) applications are presented. The three parallel modules system with fast dynamic response using single voltage loop control and inductor current calculator for input current wave shaping, inductor current sharing and output voltage regulation, while keeping the power factor very close to unity have been shown. The experimental prototype have been built with a DC output voltage −48 V and output power 750 W. Each converter operates in Continuous Conducting Mode (CCM) together with hysteresis current control. The experimental results indicate that such scheme is effective and offers the fast transient response. The results obtained are: power factor greater tha...
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