Symmetrically Pulse Width Modulated AC Chopper

In an electrical Power system, the current drawn by power converter devices from the line is distorted resulting in a higher Harmonic Distortion and low Power Factor (PF). Hence, there is a continuous need for power factor improvement and reduction of line current harmonics. Here, an Active Power factor Correction method is proposed to improve the PF and to regulate the Output Voltage of a Single Phase AC to DC Boost Converter. Small signal modeling of single-phase full bridge rectifier and its modes of operations are discussed. The inner Voltage loop is controlled by PID controller and sliding mode control is used for controlling the Outer current loop. An overall comparison is made for various voltages and loads. Output voltage tracking is also analyzed. The main aim of the proposed work is to maintain the power factor above 0.95 and to reduce the total harmonic distortion below 5%. Simulation is carried out using MATLAB software.

A new frequency conversion device topology based on matrix rectifier and AC chopper called MCAC） is proposed, which is referred as AC chopper matrix converters. First, the basic configuration of these new topologies and the fundamental principle are introduced. Then, the validity and feasibility of the new topologies are tested by digital simulation and prototype experiments. The results indicate that the output voltage transfer ratio can be larger than 1.0, the output voltage waveform is very close to standard sine wave and the harmonic contents increase slightly, overcoming the drawbacks of conventional MCs that maximum voltage transfer ratio is 0.866. This study may provide inspiration for further engineering applications.

Electronic devices such as SMPS, UPS, rectifier and electronic ballast primarily require DC power supply. Electronic switching devices draw highly distorted input current (spikes with respect to the line voltage) for a short duration, due to their non-linear nature. This results in interference with other electrical equipment, increase in Total Harmonic Distortion (THD) and poor Power Factor (PF), which further results in poor output voltage regulation. Power factor correction (PFC) circuits are being increasingly used to mitigate the problems associated with poor power factor. This paper discusses an Active Power Factor Correction (APFC) technique using voltage feed forward and voltage feedback loop. It is based upon current wave shaping technique to get the source current in phase with the input voltage. Current wave shaping is achieved by implementing voltage control loop and current control loop. This paper explains the development of boost converter as a power factor correction controller, operating in continuous conduction mode (CCM). The boost converter is also designed to regulate the output voltage. The prototype of boost active PFC has been developed for single-phase rectifier, supplying load of 80W at 400V DC. Analysis has been carried out for different load conditions which prove that the PF can be improved from 0.6 to 0.98∼0.99 with THD reduction.

In order to achieve a “healthy” power system, it is important to monitor existing values of electromagnetic interference, focusing on the quality of permanent technical products in relation to the phenomena present in the power grid. In this study harmonic distortion measurements are made in the voltage wave (THDv) and in the current wave (THDI) in order to determine the levels of harmonic distortion and power factor in the luminaries system that compose the current traffic light system (LED and halogen) in Bogota. Besides, this study contrasts the measurements found against the technical levels of THD both for voltage and for current, for each kind of luminaire recommended in the IEC 61000-3-2.

This paper describes the asymmetrical pulse width modulated (APWM) control technique for single phase AC choppers, which improves the input power factor and eliminates the harmonics of the output voltage up to a specified order. This technique also enables linear control of the fundamental component of the output voltage. The APWM switching patterns at the specified phase angle are obtained by the Newton-Raphson method and can be implemented by a one-chip microprocessor. Theoretical comparisons are made with conventional PWM technique and the computed performance indicates the superiority of the proposed APWM technique. Practical verification of the theoretical predictions is presented to conform the capabilities of the new technique. >

In, this paper, single phase AC to AC converter using pulse width modulation (PWM) is presented to control the voltage of passive R-L load. The presented AC chopper consist four IGBT switches to control the voltage across the load. The performance characteristics of PWM AC chopper using simulation and hardware are presented in this paper.

Multi-level inverter used in applications that require high power. The important factor in multi-level inverter is Total Harmonic Distortion (THD). This study discuss nine level cascaded H-bridge multilevel inverter. Also, proposed the effects of using filter on waveform and Total Harmonic Distortion (THD) of output voltage and current. Discussed LC low pass filter and sinusoidal pulse width modulation as control technique of switches. Comparison THD of nine level cascaded H-bridge multilevel inverter with and without filter. The proposed level and filter are design and simulate by MATLAB 2010 Version 7.11.0. The simulation results show the effects of using filter on THD and waveform of output voltage and current. Different methods for choosing filter value are used to illustrate the filter effect.

The rapid growth of electric vehicle (EV) deployment has created a strong demand for charging systems capable of handling higher power levels while preserving grid stability and maintaining satisfactory energy quality. In this work, a fast-charging architecture for 400 V battery systems is developed using a Vienna rectifier on the AC front end and a DC–DC buck converter on the DC stage. To enhance the performance of this topology, two complementary control techniques are combined: the Crystal Structure Algorithm (CryStAl), used for offline optimization of switching behavior, and a Random Decision Forest (RDF) model, employed for real-time adaptation to operating conditions. A clear, step-oriented derivation of the converter state–space equations is included to support controller design and ensure reproducibility. This control framework improves the key performance indices, including Total Harmonic Distortion (THD), ripple suppression, efficiency, and power factor correction. Specifically, the Vienna rectifier works on input current shaping and enhances the power quality, while the buck converter maintains a constant DC output appropriate for reliable battery charging. The simulation studies show that the combined CryStAl–RDF approach outperforms the conventional PI- and Particle Swarm Optimization (PSO)-based controllers. The proposed method achieves THD less than 2%, conversion efficiency higher than 97.5%, and a power factor close to unity. The voltage and current ripples are also significantly reduced, which justifies the extended life of the batteries and reliable charging performance. Overall, the results portray the potential of the combined metaheuristic optimization with machine learning-based decision techniques to enhance the behavior of power electronic converters for EV fast-charging applications. The proposed control method offers a practical and scalable route for next-generation EV charging infrastructure.

This paper presents steady state analysis and simulation of single pulse width modulated ac chopper fed capacitor run induction motor for variable speed operation. The d-q axis model of the cpacitor run motor is used for simulation study. Experimental results are provided to validate the simulation study.

There is a need to improve the power quality of the grid as well as the power factor implied on the grid due to the nonlinear loads connected to it. A new single phase bridgeless AC/DC power factor correction (PFC) topology to improve the power factor as well as the total harmonic distortion (THD) of the utility grid is proposed in this research. By eliminating the input bridge in conventional PFC converters, the control circuit is simplified; the total harmonics distortion THD and power factor PF are improved. The controller operates in multi loop fashion as the outer control loop calculates the reference current through innovative filtering and signal processing. Inner current loop generates PWM switching signals through the PI controller. Analytical derivation of the proposed converter is presented in detail. Performance of the proposed PFC topology is verified for prototype using PSIM circuit simulations. The experimental system is developed, and the experimental results agree with simulation results.

Electric Vehicle Charging Systems (EVCS) are gaining popularity in many countries, such as the UK, due to the rise in the number of electric vehicles and their potential impact on LV distribution networks. Consequently, there will be high growth in consumer demand for electrical power and such loads are non-linear in nature. In modern LV distribution networks, at the 11kV voltage level for example, voltage stability, harmonic distortions and poor power factor are major issues for network operators. It is expected that distribution network voltage stability should conform to the local statutory limits whereas total harmonic distortions and power factors should be within network defined parameters. Therefore, it is important to assess the impact of integrated EVCS on distribution networks with the intention of recommending measures to address potential problems. This is the main aim of the research as presented in this paper. The analysis of the total harmonic distortion and power factor of a prototype car park with integrated EVCS, developed for experimental research purposes, will be reported using the power system analysis software, Electrical Transient Analyzer Program (ETAP).

In recent years, some electrical power utility companies have experienced a significant increase in the quantity and magnitude of nonlinear loads being connected to their power systems. Loads such as fluorescent lights, rectifiers, microprocessor-driven equipment, power supplies and variable speed drives are often relatively small and well dispersed to cause a major negative impact on the power system. In this paper, the concepts of nonlinear load and harmonics are reviewed. Subsequently, calculation of the harmonic distortion and power factor are discussed in mathematical terms and supplemented with practical examples.

With offline single-phase power supplies moving toward the megahertz switching frequency range, the converter's bus capacitor becomes the bottleneck of further improvement of power density. Partial constant power operation is effective in reducing the bus capacitance and capacitor current stress for low-power applications. However, its impact on circuit design and operation design has not been studied thoroughly. With the developed circuit operation and loss model, this paper presents design considerations and power loss analysis of megahertz ac/dc converters in partial constant power operation. An adaptive constant power control is also proposed, based on the developed models, to improve the light-load efficiency and power factor. A 65 W, megahertz critical conduction mode GaN-based ac/dc converter prototype has been developed to validate the analysis and circuit operation method. Compared with power factor correction (PFC) operation, partial constant power control exhibits an efficiency drop of less than 1%. However, a 50% reduction of bus capacitance can be realized. With the proposed adaptive constant power control, the light-load efficiency and power factor can be improved to be a level similar to the PFC operation. This paper ends with a discussion of the possibility of extending the proposed operation method to higher power applications.

In many of today's solid-state lighting applications, Critical Conduction Mode (CCM) Flyback PFC converter is a popular solution due to its limited component count and simple structure with respect to other SMPS topologies. As described in international standards documents (IEC/EN 61000-3-2), drivers are required to demonstrate a power factor results greater than 0.9 and lower THD for power levels above 25W. Due to non-sinusoidal input current waveform of the traditional constant-on-time control method, achieving improved PF and THD is quite difficult. In this paper, a new control method is introduced in an effort to improve power factor and total harmonic distortion of Voltage Mode CRM Flyback PFC Converter. The work proposes injection of a compensating sin(ωt) signal component in the feedback path utilizing an additional primary transformer winding to linearize the current from the source. The detailed theoretical analysis is presented along with measurement results of a 30W high-power system prototype.

Traditional SONAR (SOund Navigation And Ranging) systems use conventional rectifiers for converting the input AC voltage for fulfilling the power requirements. The disadvantage of using these rectifiers is elevated losses in the system, resulting in lower system efficiency. The total harmonic distortion (THD) and input power factor (PF) are low. Improved performance with respect to THD and PF could be obtained by using a switched-mode power converter. A soft-switching based buck-boost PFC power converter operating in DCM is proposed in this paper. The steady-state interval of operations of the proposed configuration is presented. The steady-state analysis of the proposed PFC converter is verified in simulations carried out for a full-bridge inverter system with 1 kW / 1200 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> output fed from the proposed front end PFC converter. The simulation results are in agreement with the analysis.