Buck Rectifier Research Articles

An Improved Constant Active Power Control for Three-Phase Buck Rectifier Under Unbalanced Input Voltages and Wide AC Input Frequency

An Improved Constant Active Power Control for Three-Phase Buck Rectifier Under Unbalanced Input Voltages and Wide AC Input Frequency

Efficient self-powered cathodic corrosion protection system based on multi-layer grid synergistic triboelectric nanogenerator and power management circuits

The last few years have seen a boom in the use of triboelectric nanogenerators (TENGs) for capturing wave energy in the ocean. This work reports a multi-layer grid synergistic triboelectric nanogenerator (MLGS-TENG). In this work, the independent layer triboelectric nanogenerator in the grid format is skillfully employed, and the design of the multi-layer parallel structure can effectively increase the capture rate of blue energy in the ocean. The shell of the triboelectric nanogenerator adopts a gyroscopic structure, which, when combined with its internal architecture, operates effectively on the surface of ocean waves. Moreover, it can be very effective in harvesting low-frequency wave energy in the ocean and converting it into mechanical energy, and then converting it into electrical energy through the friction of the internal self-assembly layer. In low-frequency mechanical tests, when the frequency is about 1 Hz and the load impedance is 400 MΩ, the peak power output of the generator in a single layer can reach 77 mW/m2. Given the excellent energy harvesting performance of MLGS-TENG, it is applied to build a high-efficiency cathodic corrosion protection system in conjunction with a buck rectifier circuit. This work is of great significance for the wide application of triboelectric nanogenerators in the marine environment and provides a feasible way to ensure the long-term stability of offshore platforms.

A Novel Single/Multiple Output Multilevel Buck Rectifier for EV-Battery Charging

An electric vehicle (EV) charging system is usually implemented in two stages: a power factor correction (PFC) rectifier stage, followed by a DC-DC converter. For such power conversion, multilevel rectifiers (MLRs) offer advantages compared to a two-level rectifier, such as reducing voltage ratings of power switches and yielding high-quality input voltage waveform. In MLRs, one of the most challenging aspects is balancing the capacitors’ voltages. This article proposes a self-balancing five-level PFC rectifier with the possibility of single/multiple outputs. The proposed rectifier performs buck operation and offers a wide output voltage regulation, which is suitable for EV battery charging. The five-level operation of proposed buck rectifier with continuous conduction mode (CCM) leads to elimination of the inductive filter on the DC side and the capacitive filter on the AC side. This article presents the operating principle, modulation strategy, closed-loop control and experimental validation of the proposed topology.

Reconstructed Phase Voltages Based Power Following Control for Three-Phase Buck Rectifier Under Unbalanced Phase Voltages and Wide AC Input Frequency

In wide ac input frequency applications, such as more electric aircraft, ac input frequency of the three-phase buck rectifier varies in the range of 360–800 Hz. In this article, a reconstructed phase voltages based power following control for the three-phase buck rectifier under unbalanced input phase voltages in wide ac input frequency application is proposed. The input phase voltages are reconstructed to get more balanced modulation signals compared with the input phase voltages. The input currents are controlled to be in proportion to the reconstructed phase voltages to mitigate the imbalance of the input currents. The control strategy is simple and easy to be realized in digital. The analysis and design of the proposed control strategy and digital implementation are illustrated. An experimental prototype with 1.5 kW is built. The experimental results show that the sinusoidal input currents can be obtained when input phase voltages are unbalanced in wide ac input frequency application.

An Optimized Asymmetric Modulation Scheme for Three-Phase Buck Rectifier Without Input Current Distortion at the Sector Boundaries

Space vector pulsewidth modulation (SVPWM) is usually utilized in a three-phase buck rectifier to obtain low total harmonic distortion (THD) and low switching losses. When the conventional SVPWM scheme is applied, the input currents of the three-phase buck rectifier are distorted during the transition from even sector to odd sector, which will deteriorate the harmonics of input currents. In this letter, an asymmetric modulation scheme is proposed to eliminate the distortion of input currents of the three-phase buck rectifier during the transition from even sector to odd sector. The proposed modulation scheme combines two kinds of traditional asymmetric modulations in different sectors. A 1.5 kW experimental prototype of the three-phase buck rectifier with an ac input voltage of 115 V/400 Hz is built for more electric aircraft applications. The experimental results show that the THD of 1.3% can be achieved for the three-phase buck rectifier.

Power quality improvement for 20 MW PEM water electrolysis system

Hydrogen is an important alternative as a clean fuel for industry and power-to-gas energy storage. The water electrolysis process is a promising technology in green hydrogen production where proton exchange membrane (PEM) technology has been keenly interested. Industrial large-scale PEM electrolyzers need a high current power supply. When connected to an alternating current (AC) source, high current power rectifiers are used to convert AC to DC. Currently, the most commonly used topology in large-scale PEM electrolysis systems is the thyristor-based topology due to its technology maturity and low cost. However, this topology presents several drawbacks in terms of power quality and consequently leads to higher stack-specific energy consumption (SEC) and additional losses. In the present research, we demonstrate the potential power quality improvement for a 20 MW PEM water electrolysis system by rectifier topology upgrade. Rather than traditional thyristor-based topology, a 3-phase interleaved buck rectifier topology is proposed. The new topology presents advantages on both AC and DC sides via a validated simulation model, which is built using MATLAB/Simulink and then validated with experimental data from an industrial 20 MW PEM water electrolyzer at Air Liquide's Bécancour plant. Results show a great improvement in terms of power factor, Total Harmonic Distortion (THD), and DC-current ripple reducing the total losses and the SEC of the PEM stack, especially under partial load. Towards a higher power efficiency, the proposed rectifier topology may be considered in the construction of future large-scale PEM systems.

A V2G Enabled Bidirectional Single/Three-Phase EV Charging Interface Using Modular Multilevel Buck PFC Rectifier

The battery charging power electronics interface of an electric vehicle (EV) must be capable of bidirectional power flow to enable both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operations. In the presence of a single/three-phase AC supply, the front-end of the EV charger employs a power factor correction (PFC) rectifier, which should have the bidirectional capability to facilitate V2G mode. A conventional active rectifier functions in boost mode while performing PFC and voltage regulation. In most of the currently available EVs, however, the battery nominal voltage is low and, hence, a downstream high step-down DC-DC converter and high voltage DC bus capacitor are required in the charging interface. To overcome these issues, this work proposes a bidirectional AC-to-DC buck rectifier topology that can operate in G2V and V2G modes, both in single- and three-phase versions. The proposed topology utilizes the switched capacitors principle to achieve self-balancing of voltages in the capacitors. In addition, it is highly modular in structure. This paper describes the proposed topology, its working and modulation and its applications. The hardware proto model is used to validate the proposed power converter and the control approach to achieve PFC and voltage regulation. In addition, a comparison with other topologies is presented to demonstrate its competence.

Analysis and Improvement of the Effect of Distributed Parasitic Capacitance on High-Frequency High-Density Three-Phase Buck Rectifier

For high-density three-phase buck rectifier (3ph-BR), such as a standard full-brick size 3ph-BR, there exist obvious parasitic capacitances distributed between its dc-link output and the system ground, which lead to low-frequency distortion of input currents, and thus, serious deterioration of the input current total harmonics distortion (THD). The effect of the distributed parasitic capacitances becomes more obvious for the 3ph-BR under light load conditions. To improve the input current quality of the high-density 3ph-BR, a modified 3ph-BR is introduced in this article. The modified 3ph-BR has one low-frequency current path which realizes power transfer from ac input to dc output, and two high-frequency current paths which provide low-impedance path for high-frequency currents. The high-frequency current caused by the parasitic capacitance distributed between the dc-link output and the system ground circulates internally, rather than flow to the ac input side. Thus, input current THD of the modified 3ph-BR can be reduced. A 1-kW experimental prototype of the modified 3ph-BR with 200 kHz switching frequency and standard full-brick size is built to verify the analysis results.

An Improved Three-Phase Buck Rectifier With Low Voltage Stress on Switching Devices

An improved three-phase buck rectifier (3ph-BR) with low voltage stress on switching devices is proposed in this letter. In the conventional 3ph-BR, the voltage stress on MOSFET s is higher than the amplitude of input phase voltage. However, in the proposed 3ph-BR, the voltage stress on MOSFET s is lower than the amplitude of input phase voltage, which results in reduction of voltage stress on MOSFET s. Therefore, the cost-efficient and low voltage rating MOSFET s with low on-resistance can be utilized, which makes the proposed 3ph-BR suitable for applications that require high-efficiency and high-density. A 1.5-kW experimental prototype of the proposed rectifier is built to verify the analysis results.

A Digital Control Strategy With Simple Transfer Matrix for Three-Phase Buck Rectifier Under Unbalanced AC Input Conditions

In this letter, a digital control strategy with a simple transfer matrix between three-phase ac input voltages and dc-link voltage is proposed for a three-phase buck rectifier (3ph-BR) under unbalanced ac input conditions. The proposed digital control strategy can eliminate both the odd harmonics of the ac input currents and the even harmonics of the output voltage ripple under unbalanced ac input conditions. Compared with the state-of-the-art control strategies, the proposed control strategy does not require the extraction of the positive sequence voltage and the negative sequence voltage, thus a three-phase lock loop and complex calculation are not required. The proposed control strategy is essentially an input voltage feedforward control, which is independent of the loop bandwidth of the feedback system. Therefore, the processing speed of the digital processor is no longer the critical factor for the 3ph-BR under the unbalanced ac input conditions. The proposed control strategy makes it possible to utilize low-cost and small-sized digital processors. An experimental prototype of a 1.5-kW 3ph-BR with the proposed control strategy is built to verify the analysis results.

Analysis and Design of Three-Phase Buck Rectifier Employing UPS to Supply High Reliable DC Power

In the DC distribution system, to step down the DC voltage level from the AC grid voltage, the conventional topologies require multiple power conversion stages and bulky line-frequency transformers, which degrade their power density and cost-effectiveness. In addition, the conventional topologies suffer from a shoot-through problem resulting in their low system reliability. In this paper, to overcome the above issues, systematic design approaches of a three-phase buck rectifier with an uninterruptible power supply (UPS) and a protection algorithm are proposed to obtain the high reliability of the DC distribution system, which can deal with fault conditions and can regulate the output voltage level. It only requires a single stage of the three-phase buck rectifier. Also, a thyristor switch is added without any commutation circuits to cut off the output from the fault circuit. The shoot-through faults do not occur in the buck rectifier, leading to high reliability. A dual-active-bridge (DAB) DC-DC converter is applied as the UPS to supply the electric power from the battery when the buck rectifier is shut down under the fault conditions. Finally, the protection algorithm is proposed to detect the fault conditions and to regulate the output voltage level.

An Improved Three-Phase Buck Rectifier Topology With Reduced Voltage Stress on Transistors

The three-phase buck rectifier (3ph-BR) is suitable for applications where a voltage step-down function is required. In this paper, an improved 3ph-BR topology is proposed to reduce the voltage stress on the transistors. The freewheeling diode in the conventional topology is split into two diodes in series and the input neutral point is connected to the common point of the two diodes. With the proposed topology and the corresponding modified modulation scheme, the transistors only need to withstand the input phase voltage instead of the line-to-line voltage, bringing about the significant reduction of voltage stress. The proposed topology enables a more cost-efficient and flexible selection of the transistors. Experimental results have verified the validity of the modified topology and associated modulation scheme.

A Matrix-Based Nonisolated Three-Phase AC–DC Rectifier With Large Step-Down Voltage Gain

This paper presents a matrix-based nonisolated three-phase ac–dc converter with a current-doubler rectifier (CDR) circuit. Buck-type rectifiers are normally used for step-down ac-to-dc conversion. However, for three-phase buck rectifiers, the lower bound of rectified dc voltage is limited as the converter is severely underutilized by operating at lower modulation index. Moreover, at lower modulation index, the rms values of current increases contributing to higher conduction losses. However, by using a matrix (3 × 1) topology followed by a CDR, the desired dc output voltage can be reduced by half. The matrix topology directly converts three-phase line frequency ac voltages into intermediate high-frequency ac voltage which is subsequently, rectified using a CDR to obtain the required output dc voltage. A modified space vector modulation based modulation scheme especially suited for the proposed converter is presented for superior input power quality with reduced power loss. Comprehensive analysis and design of the proposed converter is carried out followed by simulation and laboratory-based experimental tests. Subsequently, the loss analysis of the proposed converter is carried out and a comparative evaluation of the proposed converter with the traditional six-switch buck rectifier is provided to demonstrate the suitability of the proposed converter for large step-down voltage gain. Digital implementation of the proposed modulation scheme is carried out at 40-kHz switching frequency. A hardware prototype of 500 W is developed to validate the theoretical and simulation results.

Modulation scheme analysis for high-efficiency three-phase buck-type rectifier considering different device combinations

The three-phase buck-type rectifier features a step-down ac–dc conversion function, smaller filter size, inrush current limiting capability, and potential for high efficiency, where its switching loss is dependent on the modulation scheme and the specific semiconductors used. In this paper, three different device combinations are compared through experiments on their switching characteristics for the buck rectifier application. It is shown that the switching performance of two series-connected devices becomes worse than a single device due to the superposition of the nonideal semiconductor characteristics. Moreover, the switching loss in the commutation between two switches is usually higher than the one in the commutation between a switch and the freewheeling diode. Taking into consideration both types of commutations, the switching loss of the buck rectifier is then modeled and the analytical equations are derived for four space vector modulation schemes. According to the analysis, each modulation scheme has its own field for high-efficiency application. The most advantageous modulation scheme is identified in this paper for each of the device combinations investigated.

Three-Phase High-Power and Zero-Current-Switching OBC for Plug-In Electric Vehicles

In this paper, an interleaved high-power zero-current-switching (ZCS) onboard charger (OBC) based on the three-phase single-switch buck rectifier is proposed for application to plug-in electric vehicles (EVs). The multi-resonant structure is used to achieve high efficiency and high power density, which are necessary to reduce the volume and weight of the OBC. This study focuses on the border conditions of ZCS converting with a battery load, which means the variation ranges of the output voltage and current are very large. Furthermore, a novel hybrid control method combining pulse frequency modulation (PFM) and pulse width modulation (PWM) together is presented to ensure a driving frequency higher than 10 kHz, and this will reduce the unexpected inner resonant power flow and decrease the total harmonic distortion (THD) of the input current under a light load at the end of the charging process. Finally, a prototype is established, and experiments are carried out. According to the experimental results, the conversion efficiency is higher than 93.5%, the THD about 4.3% and power factor (PF) 0.98 under the maximum power output condition. Besides, a three-stage charging process is also carried out the experimental platform.

Design Consideration for High Power Density GaN Buck-Rectifier in ISOP-IPOS Converter based dc Distribution System

GaN (gallium nitride) buck-rectifier has been proposed to realize high power density ISOP (input series and output parallel)-IPOS (input parallel and output series) converter-based dc distribution system. The ultra-low loss bi-directional switch can be developed by the GaN power device because of the low on-resistance, the high-speed switching behavior and its own device structure. The buck-rectifier using the GaN bi-directional switches has the potential to achieve higher power density than the commonly utilized boost-rectifier. Availability of the GaN-HEMT (high electron mobility transistor) for the buck rectifier has been verified taking the theoretical limit of the on-resistance and the switching loss energy into account. Design consideration for a high power density buck-rectifier has been also conducted and the application effect of the GaN bidirectional switches has been evaluated quantitatively. The ISOP-IPOS converter-based dc (direct current) distribution system takes full advantage of the buck-rectifier and the rectifier using GaN devices contributes to realizing higher power density dc distribution system.

A Three-phase Power-factor Correction Scheme Using an Autotransformer and Two Single-phase Buck Rectifiers

This paper presents a three-phase unidirectional rectifier with power-factor correction (PFC) using two modified single-phase Buck rectifiers in continuous conduction mode (CCM). The phase reduction technique using an autotransformer based on Scott Connection renders a non-isolated rectifier to operate with unity power factor. The power of autotransformer is only 14% of the total output power. Two single-phase buck rectifiers interleaved are able to regulate low voltage output. The control system is simple and it has only one voltage control loop. Theoretical analysis, design procedure and complete simulation results with closed loop operation are given. A 4-kW prototype has also been implemented in the laboratory which demonstrated to operate successfully with excellent performance.

Input-Series–Output-Parallel-Connected Buck Rectifiers for High-Voltage Applications

This paper presents input-series-output-parallel (ISOP) configuration for single-phase front-end buck rectifiers (BRs). The configuration is especially suitable for traction applications, where the complete rectification system needs to withstand high ac voltages and supply medium-power loads. The primary rectification module of the proposed configuration is based on pulsewidth-modulated BR (current source inverter topology). The desired isolation, mandatory for ISOP connection, is provided at the dc stage through a medium-frequency/high-frequency transformer. Equal power sharing by modules is achieved from the ac side through input voltage and current sharing. The proposed control scheme is configured using two loops. While the outer loop regulates the output dc voltage and active wave shaping of the source current, the inner loop ensures stable voltage sharing. The performance of the proposed ISOP configuration is verified using numerical simulation. Experimental verification is achieved through a 2-kW grid-connected laboratory prototype.

Simulation and Implementation of Single Phase Boost – Buck Rectifier Using SPMC Topology with Reduced Input Current THD

Simulation of single phase buck boost rectifier with reduced input current THD using single phase matrix converter topology is describing in this paper. Due to the bidirectional feather the operation for buck-boost rectifier can be made through matrix converter topology. And this is possible by the proper switching algorithm to control the switches for their boost and buck operation. The input current nature is almost sinusoidal with low current total current harmonics and the level of THD is below than limit that was defined in the standards of IEEE. With the proper variation in modulation index corresponding changes in the output voltage is observed of buck-boost rectifier. For the synthesis of the output voltage Pulse width modulation (PWM) technique is used. The simulation results using MATLAB/Simulink are providing to validate the feasibility of this proposed method

An Improved Power Quality BIBRED Converter-Based VSI-Fed BLDC Motor Drive

Abstract This paper presents an IHQRR (integrated high-quality rectifier regulator) BIBRED (boost integrated buck rectifier energy storage DC-DC) converter-based VSI (voltage source inverter)-fed BLDC (brushless DC) motor drive. The speed control of BLDC motor is achieved by controlling the DC link voltage of the VSI using a single voltage sensor. This allows VSI to operate in fundamental frequency switching mode for electronic commutation of BLDC motor which reduces the switching losses due to high-frequency switching used in conventional approach of PWM (pulse width modulation)-based VSI-fed BLDC motor drive. A BIBRED converter is operated in a dual-DCM (discontinuous conduction mode) thus using a voltage follower approach for PFC (power factor correction) and DC link voltage control. The performance of the proposed drive is evaluated for improved power quality over a wide range of speed control and supply voltage variation for demonstrating the behavior of proposed drive. The power quality indices thus obtained are within the recommended limits by international PQ (power quality) standards such as IEC 61000-3-2.