Input Current Waveshaping Research Articles

Input Current Distortion and Output Voltage Regulation of the Boost PFC Converter Operating with Different Control Method

There are many possible topologies for implementing power factor correction converters. Due to its advantages, the average current control method is one of the most widely used. The critical conduction mode control method is also very used and is employed here for comparison purposes. The main issues to be analyzed in the paper are the input current wave shape and the output voltage regulation. Simulation and experimental results are presented and discussed.

A comprehensive study of grid impedance and its reliability effects on variable frequency drive

<p class="Text">Grid impedance is one of the most important parameters for the satisfactory operation of variable frequency drive (VFD) and their interaction with other utilities connected to the same grid. In this research investigation a new approach to analytical evaluation and verification of grid impedance, and short circuit current is discussed. VFD under identical operating and loading conditions is connected to different grid capacities and configurations, being considered in this investigation. Grid impedance variation in terms of measured or estimated values, due to different grid connectivity affects the commutation of uncontrolled front-end rectifiers. This impacts the nonlinearity of input current wave shape, causing a significant change in current harmonics (THDi) and ripple current of DC link. This paper comprehensively investigates the reduction of DC capacitor lifetime and losses of DC inductor, and diode with various grid capacity and configurations under standard load conditions. High-frequency harmonics impact (2-9 kHz) on DC inductor losses is also analyzed. A VFD of 250 kW is considered for entire practical measurement including distortion effects and MATLAB simulation. This research may give a good insight into the sizing of VFD front-end devices. The reliability impact of VFD is also one of the important outcomes of this research.</p>

Power quality improvement in a low‐voltage DC ceiling grid powered system

Power quality is an important issue in low-voltage DC (LVDC) grids which drives light-emitting diode lighting system and many other DC loads in residential applications. The requirement of high-quality power to the lighting system necessitates power factor correction (PFC). This study presents a three-phase modular AC-to-DC converter with a simple controller for PFC in LVDC grids under balanced and unbalanced supply voltage conditions. The proposed circuit consists of three separate single-phase boost converter modules. Each module includes a diode rectifier at the front end, followed by a boost converter. The main advantage of this converter is module loss operation where the DC supply given to the lighting system and other DC loads will be continued even in case of failure of one module. The 24 V DC output voltage is regulated using an outer proportional-integral controller and the input current wave shape in each phase is improved by three individual hysteresis controllers. The controller works successfully in tracking the reference voltage changes in order to vary the regulated DC output voltage. The effectiveness of the controller has been verified by the results obtained through MATLAB/SIMULINK. A prototype model has been developed to validate this system and tested using dSPACE1104 processor.

On Analysis of Front End Current of Rectifier Converter for low THD and high PF with SEPIC

of the power electronic equipments are operated with dc supply. For reliable and stable operation, dc supply should be regulated. The regulation can be performed using buck, boost, Cuk, Sepic, Flyback regulators. Except single phase rectifier with resistive load all other rectifiers input currents are non sinusoidal in nature. This front end current distortion of rectifier converter leads to low power factor, high THD, distribution system losses, neutral harmonic currents, over rated power equipments in a power system. Researchers have developed methods to reduce above mentioned problem. But large size and bulky filter are their drawbacks. Generally, boost converter topology is used at the output to overcome the limitation of three phase diode bridge rectifiers. But this arrangement provides only greater output voltage than input voltage. Few other topology like buck-boost, Cuk, flyback converters have been proposed to offer step up or down capability to meet the requirement. Not many studies have been reported in literature to make input current waveshaping of the rectifier converter using SEPIC. The aim of this research is to develop a Sepic regulator with improved input current quality for low THD and good power factor to ensure better efficiency for the system. In this work, a detailed study has been carried out to investigate the effect of ac to dc converter on input current that eventually injects harmonics into the power system. Various topologies of the converter with input and output passive filter arrangements have been investigated and it has been found that passive filters no longer provide optimal THD, input power factor and efficiency. Finally, a single ended primary inductor converter (SEPIC) has been proposed. The performance of the SEPIC with and without passive filter has been investigated through ORCAD simulation. It is seen that SEPIC with input passive filter provides best performances in terms of THD, input power factor and efficiency for the rectifier arrangement.

Techniques to obtain single-stage power supplies with power factor correction (PFC)

In order to comply with the standards, the input current of the switch mode power supplies (SMPS) must be almost sinusoidal, i.e. the SMPS must achieve power factor correction. This requirement is normally reached with the use of an additional input converter, typically a boost, resulting in a two-stage SMPS with the inherent drawbacks: high cost and the necessity of high efficiency in each stageto obtain a reasonable global efficiency. This article introduces two simple techniques together with the control strategies that can be used to obtain single-stage SMPS, that allow the control of the output voltage and the sinusoidal input current wave shaping, without any additional stage. Another objective of this article is to investigate and to evaluate the performance of each topology that emerged from the chosen technique. Considering high-power applications, experimental results of two single-stage full-bridge topologies are also presented, in order to verify the concepts introduced in the article.

Analysis and Design of a Parallel CUK Power Factor Correction Circuit Based on Power Balance Control Technique

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 -48V and output power 750W. 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 than 0.99 and input current Total Harmonic Distortion (THD) less than 3%. The system offers 85% efficiency and provide good current sharing among the converter modules.

Single-Switch Voltage-Doubler Rectifier Derived from Half-Bridge Configuration

A novel switch-mode voltage-doubler rectifier derived from the half-bridge configuration using diodes is studied. This has an advantage that an only power switching device can provide the necessary control over the current. The arrangement tested, using an insulated-gate bipolar transistor and a controller for output voltage, is implemented to investigate the input current waveshaping. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor under the output voltage duplication.

A single-stage zero-voltage zero-current-switched full-bridge DC power supply with extended load power range

A single-stage power-factor-corrected pulsewidth modulation power converter with extended load power range is presented. The topology is based on a zero-voltage zero-current-switched full-bridge (ZVZCS-FB) inverter. Steady-state analysis of the topology shows that by operating the LC load filter in discontinuous mode, the DC-link voltage remains bounded and independent of the load level. Therefore, the load power range can be further expanded, including the no-load operating condition. The analysis also shows that the extension of the load power range is achieved without any penalty in: (1) the input power factor (due to the input current waveshaping feature); (2) the power converter efficiency (due to ZVZCS and the single-stage features); and (3) the load voltage quality (due to the high bandwidth of the phase control loop). Simulated and experimental results are included to show the feasibility of the proposed scheme.

Single-phase buck rectifier employing voltage reversal circuit for sinusoidal input current waveshaping

To ensure the continuous inductor current of single-phase buck rectifier even with a small energy storage/transfer inductor, the voltage reversal circuit is connected with a conventional circuit in cascade. This contributes to the sinusoidal input current waveshaping with a near-unity power factor. The operation, modulated with sinusoidally time-integrated input current, is simulated by a rigorous state-space method and the results obtained by this are compared with those executed for a conventional topology. The arrangement tested, using three insulated-gate bipolar transistors and a microcomputer as a PI controller, is implemented to experimentally investigate the operation. The simulated and experimental results confirm the usefulness of the rectifier presented as a single-phase buck rectifier with a good quality input current.

Analysis and design of a flyback zero-current switched quasiresonant AC/DC converter

A flyback zero-current switched (ZCS) quasiresonant AC/DC converter, functioning as a power factor correction regulator, is presented and analysed in detail. Only one active switch with simple control logic is required to achieve both input current waveshaping and output voltage regulation. The investigation of voltage and current waveforms of the proposed converter is followed by simulation and leads to a design example to verify the theoretical results. An experimental unit of 120 W was built which confirmed the analysis and simulated results.

Passive input current waveshaping method for three-phase diode rectifiers

In this paper a passive waveshaping method for a three-phase diode rectifier is presented. It is shown that application of the proposed passive method yields a significantly higher input power factor, a lower input current distortion factor, a lower input RMS current and a lower total volt-ampére (VA) rating of the reactive components than the conventional three-phase diode rectifier. Relevant input and output current waveforms, component ratings, and power factor values are derived. Different modes of operation are investigated as a means of improving performance. Finally, predicted results are verified experimentally on a laboratory prototype unit.

A comparative evaluation of SMR converters with and without active input current waveshaping

A comparative evaluation is presented of high-frequency voltage-source fed (VSF) and current-source fed (CSF) switch-mode rectifier (SMR) converters supplied from single-phase AC mains and operating under large input voltage and load fluctuations. For medium power applications (i.e. 3 kW), VSF SMR converters use passive waveshaping techniques. CSF SMR converters, on the other hand, use active waveshaping techniques. Use of active waveshaping techniques increases the input power factor from approximately 0.5 to 0.9-1.0. It is shown that when the active input current waveshaping stage is also used to regulate the SMR DC bus voltage, the converter performance can improve substantially. These improvements include reduction in switching stresses of the power semiconductor switches and reduction in the size and ratings of associated reactive components. Key theoretical results are verified experimentally. >