Low Input Current Distortion Research Articles

Design of a PFC rectifier with fast start up response and low input current distortion

For a PFC rectifier, normally designing of the PI compensator is based on the frequency domain model which is derived from the dynamic model of the rectifier, so it cannot guarantee a fast start up response. As the high input current quality and fast start up response are conflicting objectives and with improving one of them, another is degraded, for designing a PI controller which can provide both of them, a Multi-Objective optimization approach can be implemented. In this paper, for the first time, Strength Pareto Evolutionary Algorithm which is based on Pareto Optimality concept is used to gain a fast start up response as well as low input current distortion. In order to validate the proposed PI controller, simulation results are presented.

An Input-Current Shaping and Soft-Switching Drive Circuit Applied to a Piezoelectric Ceramic Actuator.

Piezoelectric ceramic actuators utilize an inverse piezoelectric effect to generate high-frequency vibration energy and are widely used in ultrasonic energy conversion circuits. This paper presents a novel drive circuit with input-current shaping (ICS) and soft-switching features which consists of a front AC-DC full-wave bridge rectifier and a rear DC-AC circuit combining a stacked boost converter and a half-bridge resonant inverter for driving a piezoelectric ceramic actuator. To enable ICS functionality in the proposed drive circuit, the inductor of the stacked boost converter sub-circuit is designed to operate in boundary-conduction mode (BCM). In order to allow the two power switches in the proposed drive circuit to achieve zero-voltage switching (ZVS) characteristics, the resonant circuit of the half-bridge resonant inverter sub-circuit is designed as an inductive load. In this paper, a prototype drive circuit for providing piezoelectric ceramic actuators was successfully implemented. Experimental results tested at 110 V input utility voltage show that high power factor (PF > 0.97), low input current total harmonic distortion (THD < 16%), and ZVS characteristics of the power switch were achieved in the prototype drive circuit.

Analog Controlled Critical Conduction Mode Three-Phase Vienna Rectifier

This paper proposed a novel analog-based critical conduction mode (CRM) control method for the three-phase three-level Vienna rectifier. By the proposed method, the simple analog CRM control can be achieved in each phase of the Vienna rectifier. All the control schemes are implemented with three low-cost analog CRM PFC IC controllers. The operation analysis of the CRM Vienna rectifier considering the parasitic capacitances is performed. Experimental results demonstrate that the valley-switching (VS) for IGBTs and the zero-current-switching (ZCS) for diodes are indeed achieved. A relatively high efficiency, a low input current total harmonic distortion, and a high power factor are tested at a 5.8 kW three-phase Vienna rectifier.

Bridgeless Isolated CUK Converter Using BLDC Motor

The CUK topology is used to propose three novel rectifiers with single phase AC-DC Power Factor Correction (PFC) without a bridge. When compared to a standard CUK Power Factor Correction rectifier, the lack of enhanced heat control and reduced conduction losses are achieved by using the current flows; there are only two semiconductor switches and one input diode bridge channel throughout each period of the switching cycles. The proposed topologies are made to operate in the mode of discontinuous conduction, resulting in a deciding element of almost unity as well as low input current Harmonic Distortion in total. Additional benefits in Discontinuous Conduction Mode operating includes zero current is switched on in the power switches, and in the output diode, zero current is turned off, as well as simplified control circuitry. The power switch can be turned on or off.

A Hybrid Control Scheme with Fast Transient and Low Harmonic for Boost PFC Converter

In this study, a new control strategy was proposed to improve transient response and the input current harmonic distortion of power factor correction (PFC) regulators operating in an average current mode. The proposed technique required only two additional gain selectors and a peak detector circuit on the feedforward voltage loop and output voltage feedback loops. It provided a direct reading for the average voltage value of feedback control loops and the peak voltage of feedforward control loops, producing PFC boost regulators with fast dynamic responses and low-input current harmonic distortion. The use of digital potentiometers for directly changing the gain of control loops did not require any divider or squarer to reduce the complexity of control circuits. The operating principles and control strategies of 300 W boost PFC with the new control strategy are presented with detailed analysis and discussion. The experimental results were satisfactory.

Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery Chargers

The rapid development of electric vehicle ultra-fast battery chargers is increasingly demanding higher efficiency and power density. In particular, a proper control of the grid-connected active front–end can ensure minimum passive component size (i.e., limiting design oversizing) and reduce the overall converter losses. Moreover, fast control dynamics and strong disturbance rejection capability are often required by the subsequent DC/DC stage, which may act as a fast-varying and/or unbalanced load. Therefore, this paper proposes the design, tuning and implementation of a complete digital multi-loop control strategy for a three-level unidirectional T-type rectifier, intended for EV ultra-fast battery charging. First, an overview of the operational basics of three-level rectifiers is presented and the state-space model of the considered system is derived. A detailed analysis of the mid-point current generation process is also provided, as this aspect is widely overlooked in the literature. In particular, the converter operation under unbalanced split DC-link loads is analyzed and the converter mid-point current limits are analytically identified. Four controllers (i.e., dq-currents, DC-link voltage and DC-link mid-point voltage balancing loops) are designed and their tuning is described step-by-step, taking into account the delays and the discretization introduced by the digital control implementation. Finally, the proposed multi-loop controller design procedure is validated on a 30 kW, 20 kHz T-type rectifier prototype. The control strategy is implemented on a single general purpose microcontroller unit and the performances of all control loops are successfully verified experimentally, simultaneously achieving low input current zero-crossing distortion, high step response and disturbance rejection dynamics, and stable steady-state operation under unbalanced split DC-link loading.

Comparative study of control techniques for three phase PWM rectifier

This paper studies and compare the performances of different control strategies of 3-phase active rectifier under different load and frequency conditions. There are three main control approaches to be investigated such as: Voltage Oriented Control (VOC), Direct Power Control (DPC) and Model Predictive Control (MPC). The traditional method VOC has been used widely in practice. Its control principle is available to many different grid-connected converter systems such as electric drive system, renewable energy conversion system. However, the problem of optimal design of the current regulators for the different operating conditions of the system is not an easy problem. The DPC and MPC methods then help to eliminate the disadvantages of the VOC. The MPC method has been now become much interesting since it offers a general solution to a multi-goal optimization problem. In the paper, the system structures and controller parameters are briefly presented. The main evaluation factors of the active rectifier are low input current distortion (THD), a unit input power factor and stable DC output voltage. Three methods are analyzed and verified using MATLAB software and measuring experiment on a real model. The obtained results show that the VOC method achieves stable quality under different load as well as the switching frequency conditions, while the MPC method may achieve good quality with a rather high switching frequency.

A Low THD Three-Level Rectifier For Gen-Set Applications

A low input current total harmonic distortion (THD) rectifier is presented, tailored around an open-end winding permanent magnet synchronous generator. Specifically, a six-level converter topology is obtained by connecting the generator stator winding to a three level T-type unidirectional rectifier on one side, and to an auxiliary two-level inverter on the other side. The T-type rectifier manages the entire active power stream and operates at the line frequency in order to minimize the switching power losses. The auxiliary inverter is instead driven by a standard PWM technique, being tasked to sinusoidally shape the input current and to actively balance the voltage across the dc-bus capacitors of the T-type rectifier. Such an inverter, being rated at a lower power and at a lower voltage than the T-type rectifier, can exploit low-cost power mosfet s. The proposed topology, featuring a very low input current THD, could well supplement in aircraft, portable or distributed generation applications, modern high-speed permanent magnet synchronous generators featuring a quite small stator impedance. Simulation and experimental results confirm the effectiveness of the proposed configuration.

Control for Three-Phase LCL-Filter PWM Rectifier with BESS-Oriented Application

This paper deals with a battery energy storage system (BESS) in only one of its multiple operating modes, that is when the BESS is charging the battery bank and with the focus on the control scheme design for the BESS input stage, which is a three-phase LCL-filter PWM rectifier. The rectifier's main requirements comprise output voltage regulation, power factor control, and low input current harmonic distortion, even in the presence of input voltage variations. Typically, these objectives are modeled by using a dq model with its corresponding two-loop controller architecture, including an outer voltage loop and a current internal loop. This paper outlines an alternative approach to tackle the problem by using not only an input–output map linearization controller, with the aim of a single-loop current control, but also by avoiding the dq modeling. In this case, the voltage is indirectly controlled by computing the current references based on the converter power balance. The mathematical model of the three-phase LCL-filter PWM rectifier is defined based on the delta connection of the filter, which accomplishes the requirements of a 100 kW BESS module. Extensive simulation results are included to confirm the performance of the proposed closed-loop control in practical applications.

A Remotely Central Dimming System for a Large-Scale LED Lighting Network Providing High Quality Voltage and Current

Standard TRIAC-based dimmers introduce power quality issues especially for a large-scale lighting network. Other existing dimming protocols involve additional wiring systems and/or additional controllers to light emitting diode (LED) drivers. This paper proposes a central dimming system for a large penetration of LED lamps. The dimming system is remotely controlled through a webpage or a desktop application. Dimming is achieved while maintaining high voltage and current quality waveforms, which results in a high power factor and a low input current harmonic distortion. The system does not require additional wiring or specific adjustments to commercial dimmable LED drivers. The system allows scheduling a dimming profile to endorse energy saving. In the proposed dimming system, dimming function is achieved by connecting a voltage source converter (VSC) between the grid and the LED lamps. An advanced feature is added to the VSC dimmer to remotely send/receive messages between the system and the user through a graphical user interface. Thus, the user can communicate with the VSC dimmer by sending commands and receiving feedback information. The influence of communication delay on system stability is analyzed by using small signal models. A VSC dimmer prototype (500 VA/120 V) has been built with a communication module to provide remote control. Experimental results and comparisons between utilizing the TRIAC-based dimmer and the VSC dimmer for dimming function are discussed in the paper.

Boundary Conduction Mode Modified Buck Converter with Low Input Current Total Harmonic Distortion

Buck Power Factor Correction (PFC) converter is widely used for a broad range of AC/DC applications because of its many advantages like protection against short circuit, high efficiency at universal input voltage, low output voltage, less voltage stress on the switch, low inrush current and low component cast. However the inherent dead zone introduces a large harmonic distortion in the average input current, resulting in a low Power Factor (PF) and high Total Harmonic Distortion (THD). A constant on-time controlled Boundary Conduction Mode (BCM) buck-flyback converter is introduced in this paper. It can achieve low input current THD and high PF. The operating principle of the traditional and proposed converter is discussed and the effectiveness of proposed topology is evaluated by simulation results. Keywords: Boundary Conduction Mode (BCM), Buck Converter, Power Factor (PF), Total Harmonic Distortion (THD)

A Digital Pulse Train Controlled High Power Factor DCM Boost PFC Converter Over a Universal Input Voltage Range

In this paper, a digital-based pulse train (PT) control technique for a boost power factor correction (PFC) converter operating in a discontinuous conduction mode (DCM) is presented, which can achieve nearly unity power factor (PF) over a universal input voltage range. Different from traditional digital control techniques, which usually require complex arithmetic operations, the digital-based PT control technique only needs a simple operation. Besides, a DCM boost PFC converter with digital PT control can operate at a high switching frequency, which is less dependent on the processing speed of a digital controller. Thus, the proposed control strategy can be implemented with general purpose digital controllers, such as low-speed and low-cost microcontroller unit, for the DCM boost PFC converter where the cost is a focus. The operation principle of the digital PT controlled DCM boost PFC converter is analyzed. Experimental results are provided, which show that high PF and low input current total harmonic distortion can be maintained over a universal input voltage range of 90–264 V ac.

Design and analysis of a simple predictive power controller for a 1.0‐kV single‐phase NPC PWM rectifier

SummaryThis paper proposes a 1‐kV single‐phase neutral point clamped (NPC) PWM rectifier with a simple predictive power controller (PPC). It includes the three‐level NPC converter and a simplified PPC. This system achieved to feature multi‐level converters and the ability to provide high voltage gain, and a control with accurate and straightforward predictive strategy without the need of PLL and PI controller. It also takes advantages of a digital delay compensator unit, a user‐friendly single‐phase three‐level space vector modulation (SVM) with neutral point balancing, and bidirectional active and reactive power flow. The proposed rectifier provides low input current harmonic distortion (THD &lt; 2%), input sinusoidal current waveforms, zero or desired reactive power flow, fast dynamic response (=5 cycles), high stability, high efficiency, and the lower DC voltage ripple (&lt;6%). Simulations have been carried out for a 1 kV/20 kW rectifier under different conditions. In this analysis, various practical conditions have been investigated and discussed in details. Furthermore, the proposed system was compared with the other literature and conventional methods.

Optimising the performance of three-phase neutral-point clamped rectifier under disturbed AC mains

In this paper, a novel simplified control technique is proposed to control three-phase neutral-point clamped bidirectional rectifier using optimised switching sequences for disturbed AC mains. In space-vector modulation (SVM) technique using optimised switching sequences, duty ratio and sampling periods in each region are very important. In other words, reference vector trajectory shape and the time spent by the reference vector in each region are very important to obtain exact switching under any supply conditions. With the use of optimised switching sequences, even under ideal supply conditions, it is depicted that source-side and load-side parameters deviate from acceptable limits, and a DC-bus capacitor voltage unbalance occurs. Under the influence of disturbed AC supply, source-side and load-side parameters deviate more beyond acceptable limits which cause a very large unbalance in DC bus capacitor voltages. This non-ideal performance of the converter is responsible for the deterioration of quality of source currents and a large stress on power semiconductor devices. A new algorithm is proposed in this paper to make the converter performance ideal even under ideal and non-ideal supply conditions. According to supply conditions, the proposed technique varies the speed of the reference vector and, also at the same time, forms a required trajectory while passing through the most effective regions of SVM hexagon. The proposed technique maintains parameters within acceptable limits for source side and load side in terms of unity power factor, low input current total harmonic distortion (THD), minimum switching losses and reduced-rippled, well-regulated DC-bus voltage and also at the same time DC-bus capacitor voltage balance. The simulation results are presented to demonstrate the effectiveness of the proposed control technique.

The Optimal PWM Modulation and Commutation Scheme for a Three-Phase Isolated Buck Matrix-Type Rectifier

This paper first starts with reviewing several commonly practiced PWM schemes for the three-phase isolated buck matrix-type rectifier. Then, an optimal six-segment PWM scheme (“Type A”) is proposed. The analysis shows “Type A” PWM scheme has lower duty-cycle loss, maximum output inductor current ripple, and minimum switching loss comparing with other PWM schemes when the mosfet devices are employed. In addition, a low input current total harmonic distortion (THD) can be achieved with duty-cycle compensation. Finally, the steady-state analysis of duty-cycle loss, inductor current ripple, and THD are all compared and verified by the experimental results for “Type A” PWM and eight-segment PWM (“Type E”).

A Digital Predictive Peak Current Control for Power Factor Correction With Low-Input Current Distortion

A digital predictive peak current control (PPCC) employing the adaptive slope compensation is proposed in this paper. The PPCC precisely predicts the peak current reference with the adaptive slope compensation according to operation regions and load conditions. Thereby, the PPCC can control the peak inductor current, and it significantly reduces the total harmonic distortion compared to that of the conventional digital average current control with duty ratio feed-forward which is widely used. In addition, parts of the PPCC are implemented by utilizing the internal high-resolution ramp generator and comparator of a digital signal processor without external components. The principle and analysis of the PPCC are presented, and the performance and feasibility are verified by experimental results with universal input ( $90\; {\rm V}_{\rm rms} \sim 260\; {\rm V}_{\rm rms}$ ) and $750\; {\rm W}-400\; {\rm V}$ output laboratory prototype.

Performance evaluation of three‐phase, neutral‐point clamped bi‐directional rectifier for supply and load perturbations

In this study, an improved performance three-phase neutral-point clamped bidirectional rectifier with modified control scheme is proposed. The proposed control strategy takes into consideration the amount/degree of deviation of source voltage from desired rated value during supply perturbation and accordingly modifies the reference current template for each phase individually which is termed as compensated reference current. In other words, magnitude, shape and phase of compensated reference current waveform for each phase are different depending on amount of deviation of that phase. A complete mathematical model of rectifier using pulse width modulation technique is developed. The performance of the converter is evaluated in terms of near unity input power factor, low input current total harmonic distortion, reduced ripple factor of the regulated DC output voltage and particularly the neutral-point voltage balance under different load conditions both for rectification and inversion modes of operation. It is shown that the three-level AC to DC converter with the proposed control scheme displays better performance under source voltage perturbations such as voltage sag, swell, unbalance, harmonics, frequency variations as well as phase angle deviations which are regularly encountered in practical environment.

Design and Implementation of a Single-Stage Driver for Supplying an LED Street-Lighting Module With Power Factor Corrections

This paper proposes a novel single-stage light-emitting diode (LED) driver for street-lighting applications with power factor corrections (PFC). The presented driver integrates a modified bridgeless PFC ac-dc converter with a half-bridge-type LLC dc-dc resonant converter into a single-stage conversion circuit topology. The proposed ac-dc resonant driver provides input current shaping, and it offers attributes of lowered switching losses to the soft-switching functions obtained on two power switches and two output-rectifier diodes. The proposed driver features cost-effectiveness, high circuit efficiency (>92%), high power factor (>0.99) and low input current total harmonics distortion (<;8%). A prototype driver is developed for supplying a 144-W-rated LED street-lighting module with utility-line input voltages ranging from 100 to 120 V, and experimental results demonstrate the functionalities of the proposed LED driver.

A Novel Single-Stage HPF Electronic Ballast With Coupled Inductors for Fluorescent Lamps

This paper proposes a novel single-stage electronic ballast with high power factor (HPF) for supplying fluorescent lamps. The presented electronic ballast integrates a dual boost converter with coupled inductors and a half-bridge series-resonant parallel-loaded inverter into a single-stage power conversion topology. The features of the ballast are cost-effectiveness, HPF (PF > 0.98), high circuit efficiency (>90%), low input current total harmonic distortion (THD <; 7%), low level of crest factor (CF <; 1.4), and zero-voltage switching obtained on both two power switches. Operational principles, design equations, and experimental results of one T5-type fluorescent lamp with a rated power of 21 W operating at 50 kHz switching frequency with 110 V-RMS line input voltage are presented. Satisfactory results demonstrate the feasibilities of the proposed ballast.

Dimmable Single-stage Sepic-buck Converter for Led Lighting With Reduced Storage Capacitor

This paper presents an analysis and design of a Light Emitting Diode (LED) driver aiming to eliminate or substitute the electrolytic capacitors. Considering the low lifetime of electrolytic capacitors compared to LEDs, this topology aims for reducing the storage capacitance and replaces it by a longer lifetime capacitor, increasing the overall system life span. This reduction is based on designing of the control dynamic with a compromise between the input current distortion and the output current ripple. The power factor correction (PFC) stage is based on a Single Ended Primary Inductance Converter (SEPIC) operating under discontinuous conduction mode (DCM) because of its low input current distortion characteristic making it possible to eliminate the electromagnetic interference (EMI) filter. The power control (PC) stage is performed by a Buck converter using its output current source behavior, suitable for LED application. A 106 W LED driver prototype is implemented resulting in 27.1% total harmonic distortion (THD), 50% current ripple on the LED and an efficiency of 92.18%. Furthermore an effective simple dimming strategy is proposed and implemented by an LED parallel active switch.