AC Input Voltage Research Articles

A Novel Shunt Zigzag Double-Tap Low-Harmonic Multi-Pulse Rectifier Based on a Three-Stage Power Electronic Phase-Shifting Transformer.

To solve the problem of the large size of traditional industrial frequency phase-shift transformers and the harmonic distortion of multi-pulse wave rectifier systems, this paper proposes a three-stage shunt zigzag power electronic phase-shift transformer based on a double-tap multi-pulse wave rectifier, which combines the power factor correction (PFC) converter with the voltage-type SPWM inverter circuit to form a power electronic converter to realize the frequency boost and power factor correction. Through AC-DC-AC conversion, the frequency of the three-phase AC input voltage is increased, the number of core and coil turns in the transformer is reduced to reduce the size of the phase-shifter transformer, a zigzag structure of the phase-shifter transformer is used to solve the unbalanced distribution of current between the diode bridges, and a passive harmonic suppression method on the DC side is used to generate a loop current by using a group of single-phase rectifier bridges to regulate the input line current of the phase-shifter transformer. The phase-shifted voltage is input into two three-phase diode rectifier bridges to rectify and supply power to the load. Simulation and semi-physical test results show that the proposed method reduces the total harmonic distortion (THD) value of the input current of the phase-shifted transformer to 7.17%, and the THD value of the grid-side input current is further reduced to 2.49%, which meets the harmonic standard and realizes the purpose of power factor correction as well as being more suitable for high-power applications.

A Novel Single-Stage AC/DC Converter Integrated Interleaved DCM Boost PFC and LLC DC–DC With Reduced Bus Voltage

Due to the applied pulse frequency modulation (PFM) control and switch integration, single-stage Boost-LLC AC/DC converters suffer from high bus voltage which makes them difficult to operate for high voltage input. To solve this issue, a novel single-stage AC/DC Converter by incorporating the interleaved DCM boost cell and an LLC cell is proposed. Different from the existing topology, in the proposed converter, two capacitors employed for splitting the ac input voltage into two parts are placed before the rectifier bridge. Thus, the voltage across each PFC cell is halved and the bus voltage can be significantly reduced. Furthermore, two high-frequency diodes and one filter capacitor are omitted, which helps improve the zero-crossing distortion of the input current. More importantly, the circuit efficiency is thus increased. Hence, low bus voltage, low component count, and high efficiency are the main advantages of the proposed converter. Simulations and experimental results are presented to prove the above features of the proposed converter.

A Novel Series 24-Pulse Rectifier Operating in Low Harmonic State Based on Auxiliary Passive Injection at DC Side

To reduce the current harmonics on the input side of a multi-pulse rectifier, this paper proposes a low harmonic current source series multi-pulse rectifier based on an auxiliary passive injection circuit at the DC side. The rectifier only needs to add an auxiliary passive injection circuit on the DC side of the series 12-pulse rectifier, which can change its AC input voltage from 12-step waves to 24-step waves. We analyzed the working mode of the rectifier, optimized the optimal turn ratio of the injection transformer from the perspective of minimizing the total harmonic distortion (THD) value of the input voltage on the AC side, and analyzed the diode open circuit fault in the auxiliary passive injection circuit. Test verification shows that, after using the passive harmonic injection circuit, the THD value of the input voltage of the AC side of the rectifier is reduced from 14.03% to 4.86%. The THD value of the input current is reduced from 5.30% to 2.16%. The input power factor has been increased from 98.86% to 99.83%, and the power quality has been improved.

Optimized control strategy of totem-pole PFC converter based on two-stage charger

In this paper, the operating principle and control scheme in the CCM mode of the front-end totem pole PFC are analyzed. Based on the operating characteristics of the circuit topology, a PR controller is used to control the input current. When the grid voltage contains harmonic signals, a low harmonic compensator is cascaded in the original PR controller to reduce the impact of harmonics in the grid voltage on the control effect. Then input current distortion is analyzed when the AC input voltage crosses zero point, and the corresponding optimization method is proposed. Finally, different experiments are carried out to verify the effectiveness of the proposed method.

Comprehensive Analysis on Power Factor Correction Circuit

With the development of industrial power electronics, the current era can be called the "world energy era". Energy has never been more important, especially with the growing demand for today's "green" energy sources. power factor correction circuits have become an integral part of most current AC voltage input power applications, whether it is automotive battery power, portable energy storage (such as power banks), traditional server power, or lighting systems. However, the basic principles of power factor correction converters are rarely described in detail. This paper will summarize and illustrate the basic principle of the power factor correction circuit, and first introduce the research background of power factor correction technology; At the same time, three operating modes of power factor correction circuit are analyzed: continuous on-mode (CCM), critical on-mode (CRM) and discontinuous on-mode (DCM), and their advantages and disadvantages are to be further discussed. In addition, the PFC converters with optimized topology and excellent performance will be introduced, and the application prospect and prospect of three-phase PFC converters will be presented.

A self-powered synchronous magnetic flux extraction interface for electromagnetic energy harvesting

In this work, a self-powered synchronous magnetic flux extraction (SP-SMFE) circuit is proposed for electromagnetic energy harvesting. It's a bridgeless direct ac-dc converter, that uses a large-value external inductor L to store and transfer energy. By comparing the voltage across L, SP-SMFE achieves the peak detection of the inductor current Iem without an external power supply and transfers the energy to the load when Iem reaches the peak value, which can maximize the energy extraction from the electromagnetic transducer. Simulation results show that the output power of SP-SMFE is much higher than that of the voltage doubler circuit under the load range of 1–100 kΩ and the frequency range of 20–140 Hz. The input ac voltage with 4 V amplitude is rectified and stepped up to 59 V dc by SP-SMFE at the load of 100 kΩ and the frequency of 40 Hz. Experiment results verify the effectiveness of the SP-SMFE circuit in power harvesting at low frequencies and large loads.

Design and Control of Two Stage Battery Charger for Low Voltage Electric Vehicles Using High Gain Buck-Boost PFC AC-DC Converter

The design and control of a two-stage onboard battery charger (OBC) for the low-voltage electric vehicle (LVEVs) are presented in this study. The presented charger operates over a wide range of AC input voltage at high power factor. The presented charger utilizes a bridgeless high gain high power factor AC-DC converter with continuous input current characteristics at its front end. At the back end of the charger, an isolated Cuk DC-DC converter is employed to control and implement different battery charging modes, viz. constant current (CC) and constant voltage (CV) charging profiles. The presented AC-DC converter operates under discontinuous current mode (DCM) operation and achieves minimum control complexity at the AC-DC stage. The DCM design and high voltage conversion ratio allow it to function reliably over a comprehensive range of input and intermediate DC link voltage. This study covers the charger's design for a power rating of 650 W and output battery voltage of 24 to 72 V. The overall operational analysis and effectiveness of the design are verified through both simulations and experimental implementation and the performance is compared with other contemporary power factor correction (PFC) topologies on various parameters.

Current THD and Output Voltage Ripple Characteristics of Flyback PFC Converters with LED Lamp and Nonlinear RL Loads

This study analysedthe characteristics of total harmonic distortion (THD) and output voltage ripple in a flyback PFC converter circuit under two different loads, which are the LED lamp modules and nonlinear RL loads. The converter was designed to step down the AC input voltage (90 V-265 V) to a DC output voltage of 80 V DC for both loads, each with an output power of 16 W. The main objectives were to observe and assess current THD and output voltage ripple for both loads using two different capacitances of the output capacitor, which are 2400 μF and 6 μF, respectively. The results demonstrated that using smaller capacitors(6 μF), it increased output voltage ripple, which it increased for the LED lamp load from 10% to 25% and for the nonlinear RL load it increased from 15% to70%. However, with the same smaller capacitors (6 μF), it reduced current THD for both loads, which for the LED lamp load it reduced from 12% to 10.3%, and for the nonlinear RL load it reduced from 13.7% to 8.3%. From these results, with 2400 μF of the output capacitor, it provided better performance in terms of current THD and output voltage ripple for both load types.

A Family of Single-Stage AC/DC Converters Integrated Interleaved PFC and Resonant DC/DC Circuits

To address the high bus issue of conventional boost or buck-boost PFC integrated resonant DC/DC type single-stage converters under high voltage input, a family of single-stage AC/DC converters integrated interleaved PFC and resonant DC/DC circuits is proposed in this paper. Unlike traditional solutions, the AC input voltage of the proposed three interleaved PFC structures is divided into two parts by two capacitors before the rectifier bridge. Thus, two high-frequency power diodes and one filter capacitor are omitted. Furthermore, the reduced bus voltage can be simultaneously obtained with fewer devices. Correspondingly, a better zero-crossing performance of input current can be achieved theoretically. Most importantly, the circuit efficiency also can be increased. Using the common LLC circuit as DC/DC stages, simulations in PSIM are performed to verify the improved zero-crossing of input current. To introduce the proposed converters, the operation principles, design considerations, experimental results, and related comparisons for the proposed structure II with LLC cell are presented comprehensively, achieving at least a 2.3% improvement in efficiency under 220Vac nominal input and 100W load conditions, while maintaining reduced bus voltage and similar PF values. In addition, the experimental results of the topology I and III are also given to prove the validity of the proposed family converters.

Dual Outputs Switch Mode Power Supply (DOSMPS) Utilizing Forward Converter Topology

Experimental works of dual, 5 volt DC outputs switch mode power supply (DOSMPS) is presented in this paper. To design, construct and evaluate the DOSMPS using forward converter topology are the objectives of this article. In this work, a 556 timer was picked as the pulse width modulator. The 556 timer was picked because it is widely used, cheap and capable of producing stable dual pulse width modulations. Since, this work targeted dual DC outputs, two forward converter circuits were built. However, switching frequencies at two transistors were controlled by only one 556 timer. The complete circuit of the DOSMPS consist of full bridge rectifier, smoothing capacitor, two high frequency transformers and two forward converter circuits. At the first stage of this work, the DOSMPS circuit was designed using Proteus software. Later, the complete DOSMPS circuit was constructed on two breadbroads after all of the electronic components and devices were available. Important parameters such as the input and output voltages and duty cycles were measured using digital oscilloscope and multimeter. Results from these measurements have shown that the designed circuit can convert single-phase 24 Vrms 50 Hz AC voltage input into dual and stable 5±0.1 V DC outputs. Also from this work, it was observed that, pulsed DC voltages with peak value of 2 V and frequency less than 20 kHz are sufficient in controlling the switching frequencies of both BJT transistors. This allows the regulation of the output voltage within the desired range. Analysis carried out after the measurements has shown close correlation between the theoretical and experimental results, where the calculated and measured switching frequencies had only deviated by 1.1%.

A 13.56 MHz Low-Power, Single-Stage CMOS Voltage-Boosting Rectifier for Wirelessly Powered Biomedical Implants

In this paper, a low-power, single-stage, active rectifier based on a new charge-pump circuit is presented to be used in biomedical implants. The proposed circuit not only rectifies the AC input voltage to a DC voltage but also amplifies the DC output voltage to a higher level. Low-loss MOS switches are used in the structure of the designed circuit to provide high power conversion efficiency. In addition, by using two comparators, the reverse leakage current is somehow eliminated, resulting in a higher increase in the power efficiency. By tying the source and bulk terminals of the utilized transistors, the body effect problem has been solved, and by connecting the p-substrate to the ground, which is the lowest voltage in the circuit, the latch-up phenomenon is eliminated without any extra circuit. The proposed rectifier is implemented and post-layout simulated in a 0.18 µm standard CMOS technology. According to the simulation results, 1.205 V output DC voltage is achieved from an AC input signal with the peak-to-peak amplitude of 1 V at the operating frequency of 13.56 MHz with a 3 kΩ load resistance. The total active area of the designed circuit is 0.167 mm2 with a maximum power conversion efficiency of 98.2%, output power in the range of 0.5–1.5 mW, and voltage conversion ratio of 120%.

Analytical and Numerical Investigations of Electrokinetic Micromixing in Electroosmotic Micromixers

Improvement in mixing quality under of low Reynolds number hydrodynamic flows in microchannel devices is mandatory and essential. This paper investigates the electrokinetic effects on mixing of two miscible fluid streams (ethanol and water) in two different micromixers (i.e., circular and square micromixers) with the help of analytical, semianalytical, and numerical methods. In the analytical method, we develop a closed form solution in order to evaluate normalized electric potential distribution as a function of normalized microchannel channel width, as well as a semianalytical solution for normalized concentration distribution across the normalized microchannel width. In addition, in the context of the numerical method (based on the Finite Element Method approach), we perform a parametric study by varying the input AC voltage and compare the extent of mixing in the two proposed micromixers. Moreover, we validate the analytical and semianalytical results with obtained numerical results, and also compare them with previously published literature. A good agreement between the analytical and semianalytical results with the obtained numerical solution is observed as ±15%.

A Bridgeless Cuk-BB-Converter-Based BLDCM Drive for MEV Applications

This article presents a brushless DC motor (BLDCM) drive for a maritime electric vehicle (MEV) application. The presented BLDCM drive uses a bridgeless Cuk-buckboost (BL-Cuk-BB) converter for input-side power factor (PF) improvement. The BL-Cuk-BB converter uses the buckboost converter for the negative half-cycles of the input AC voltages and the Cuk converter for the positive half-cycles. In the case of MEVs, the drive systems are generally fed by diesel engine generators (DEGs). The asymmetric BL-Cuk-BB converter is operated in a discontinuous inductor current mode (DICM) in the present work to attain better power quality. The usage of a second-order buckboost converter with a fourth-order Cuk converter results in a decrement in the net order of the system. Additionally, the input inductor of the Cuk converter also participates as the filter component along with capacitor C2 during buckboost converter operation to enhance the power quality. The total component count reduction in the BL-Cuk-BB converter is also achieved by eliminating the usage of extra/external back-feeding diodes, which are generally used in bridgeless schemes. The present scheme uses the inbuilt anti-parallel diodes for the same purpose. The lesser components requirement in the BL-Cuk-BB-converter-based BLDCM drive implies lesser cost and volume, along with greater reliability, lower conduction losses, and lower weight of the BLDCM drive, which adds to the merits of the model. The paper includes a detailed mathematical model and stability analysis using pole-zero maps and bode plots of the BL-Cuk-BB converter for each half-supply AC voltage cycle. The BL-Cuk-BB-converter-based BLDCM drive for an EV application has been developed on the MATLAB/Simulink platform for a DICM operation, and the MATLAB simulation results have been presented for validation of the BL-Cuk-BB-converter-based BLDCM drive.

Efficient Dual Output Regulating Rectifier and Adiabatic Charge Pump for Biomedical Applications Employing Wireless Power Transfer

A power management unit (PMU) is an essential block for diversified multi-functional low-power Internet of Things (IoT) and biomedical electronics. This paper includes a theoretical analysis of a high current, single-stage ac-dc, reconfigurable, dual output, regulating rectifier consisting of pulse width modulation (PWM) and pulse frequency modulation (PFM). The regulating rectifier provides two independently regulated supply voltages of 1.8 V and 3.3 V from an input ac voltage. The PFM control feedback consists of feedback-driven regulation to adjust the driving frequency of the power transistors through adaptive buffers in the active rectifier. The PWM/PFM mode control provides a feedback loop to adjust the conduction duration accurately and minimize power losses. The design also includes an adiabatic charge pump (CP) to provide a higher voltage level. The adiabatic CP consists of latch-up and power-saving topologies to enhance its power efficiency. Simulation results show that the dual regulating rectifier has 94.3% voltage conversion efficiency with an ac input magnitude of 3.5 Vp. The power conversion efficiency of the regulated 3.3 V output voltage is 82.3%. The adiabatic CP has an overall voltage conversion efficiency (VCE) of 92.9% with a total on-chip capacitance of 60 pF. The circuit was designed using 180 nm CMOS technology.

A new modulation strategy on isolated battery charger with wide input and output voltage range

AbstractA new wide voltage operation range isolated battery charger, which is composed of an asymmetric T‐type AC–DC power rectifier and a modified re‐configurable half bridge DC–DC power converter, is proposed in this paper. The asymmetric T‐type rectifier adopts different modulation strategies under different AC bus voltage amplitudes and different battery voltages for increasing power conversion efficiency. As the isolated DC–DC power stage, a modified re‐configurable half bridge converter applies a three‐winding transformer to achieve a wide output operation range. The proposed battery charger operates over a wide AC input voltage range and wide DC output voltage range. A 3.2 kW hardware battery charger prototype is built to adapt AC voltage between 85 and 265 V. Both constant current and constant voltage modes are implemented experimentally to charge the battery up to 6.5 A from 50 to 500 V. The experimental results prove that the proposed asymmetric T‐type rectifier adopts different modulation strategies under different AC bus voltage amplitudes and different battery voltages can increase the power conversion efficiency, the proposed DC–DC converter can output the DC voltage from 50 to 500 V and the proposed battery charger can achieve around 94% efficiency.

Experimental Validation for Artificial Data-Driven Tracking Control for Enhanced Three-Phase Grid-Connected Boost Rectifier in DC Microgrids

This article introduces the control and operation of a grid-connected converter with an energy storage system. A complete mathematical model was presented for the developed converter and its control system. The system under study was a small microgrid comprising an AC grid that is feeding a DC load through a converter. The converter was connected to the AC grid through an R-L filter. The classical linear controllers have limitations due to their slow transient performance and low robustness against parameter variations and load disturbances. In this paper, machine-learned controllers were used to dealing with those drawbacks of the traditional controller. First, a study for conventional nested loop Proportional Integral (PI) was introduced for both outer and inner loops PI-PI controller. A Data-Driven Online Learning (DDOL) controller was then proposed. A comparison between the normal traditional PI-PI controller and the proposed DDOL ones was made under different operating scenarios. The converter control was tested under various operational conditions, and its dynamic and steady-state behavior was analyzed. The model was done through a MATLAB Simulink to check the normal operation of the network in a grid-connected mode under different load disturbances and AC input voltage. Then, the system was designed, fabricated, and implemented in a hardware environment in our Energy Systems Research Laboratory (ESRL) testbed, and the hardware test results were verified. The results showed that the proposed DDOL controller was more robust and had better transient and steady state performances.

Development of a Smart Static Transfer Switch Based on a Triac Semiconductor for AC Power Switching Control

Power system disruptions can be categorized as issues with the quality of electricity brought on by voltage sags, lightning strikes, and other system-related interferences. The static transfer switch (STS) has recently emerged as the most important technology for electric power transmission, distribution, and control systems to manage power supply during power system disruption issues, particularly in cost-effectively supplying power to critical loads and sensitive loads without interruption. In this paper, for the switching between the two AC sources during the voltage disruptions issue with low transfer time, a smart static transfer switch (SSTS) based on a digital switching algorithm and Triac semiconductor switch is proposed and experimentally tested. A digital switching algorithm based on online AC voltage sensing and zero-crossing detection is proposed and implemented inside a DSP MCU. The printed circuit board (PCB) of the proposed SSTS is designed and manufactured for the experimental performance investigation with different AC input voltage conditions. A comparative study based on the advantages and disadvantages of the proposed SSTS system with the previous works is also presented. A smart static transfer switch with a transition time of less than one cycle and a digital protection technique during fault conditions is obtained in this work.

Single-Phase Hybrid Switched-Capacitor PFC Boost Rectifier With Low Voltage Gain

Power factor correction (PFC) rectifiers based on the classic boost topology have become widespread owing to their current input features, and can obtain optimal results in terms of power quality. However, several applications require an output dc voltage lower than the ac input voltage. In such cases, two-stage topologies provide lower voltage values at the output, which increases the number of components. Moreover, such topologies tend to incur higher losses and are costly. Therefore, a unidirectional hybrid single-stage single-phase PFC boost rectifier with a switched-capacitor cell and low voltage gain is proposed. Furthermore, the proposed topology has two active switches, and natural balance exists between the voltages of the capacitors. Therefore, an additional control system is not required. The proposed topology was theoretically analyzed and experimentally validated using a 1 kW prototype with two different operational situations: (A) 127 V ac and 100 Vdc; (B) 220 Vac and 200 Vdc, input and output voltages, respectively. The experimental results essentially reveal that the power factor is approximately one, and the total harmonic distortion of the input current is 4.6%. The maximum efficiency achieved was 96.5% in the operational situation (B).

Comparative Study Between Sliding Mode Controller and PI Controller for AC/DC Bridgeless Converter Under Uncertain Parameters

Abstract In this paper, a comparative study between nonlinear sliding mode controller (SMC) and standard PI controller for stabilizing bridgeless AC/DC converter under uncertain parameters is presented. This type of converters is widely used in harvesting low energy systems as in wind turbine, piezoelectric transducers and heat exchange transducers. Designing robust controllers to enhance the efficiency and accuracy of these converters has become a promising track in control engineering field. The traditional bridge rectifier is widely used in the majority types of AC/DC conventional converters to gain the rectified DC voltage from the low AC input voltage source. However, these traditional converters are not effective for the low output voltage of renewable sources due to the voltage drops across rectifier’s diodes. The proposed SMC-PI controller is used to enhance the stability and the response of these converters under uncertain parameters comparing with the standard PI controller. The proposed approach consists of both Boost and Buck-Boost converters with two controllers in order to maximize the useful output energy from the source. The graphical method has been used to obtain the limitation of the coefficients of the standard PI controller. A parameter space approach is used to find all robust stabilization PI coefficients and the stability regions. A comparative study using simulations in MATLAB is presented to ensure the effectiveness and robustness of the proposed SMC-PI controller under some external disturbances.

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.