Advanced Pulse Width Modulation Techniques Research Articles

A Control Method to Reduce Overshoots in High-Frequency Link Current and Voltages at Load Transients of a Dual-Active-Bridge Series-Resonant Converter

Dual Active Bridge Series Resonant Converter (DABSRC) is well researched in the literature to find out a suitable pulse width modulation (PWM) technique that can achieve voltage regulation, zero voltage switching (ZVS), and minimum rms current in high frequency (HF) link. Although the advanced PWM techniques achieve desired performance at steady state, the HF link current and voltages suffer from huge overshoots during the load transients, which can damage the semiconductor devices and can cause the saturation of the high frequency transformer. Therefore, in this paper, a relationship is derived between the pole positions and the percentage overshoot, so that any design with the trade-off between the fast dynamics and overshoot can be done analytically. As the system involves multiple state and input variables, which are also closely coupled, a multivariable state feedback controller design is proposed to control the dynamics of all the HF link state variables simultaneously. In any DAB-based topology, the peak volt-ampere (VA) rating of the passive components can increase by 80% due to these overshoots. The proposed control successfully restricts the overshoots below 25% with a settling time of 5 ms for the output voltage. The experimental verification is carried out in a 2.25 kW hardware prototype.

Advanced PWM Techniques for Multi-Level Inverters With a Multi-Level Active CM Noise Filter

Pulsewidth modulation (PWM)-based power electronics inverters are being widely used for various applications, including motor drives. However, the common-mode voltage (CMV) resulting from switching operations in the PWM inverters causes significant performance degradation of the system and can cause potential damage to motors. Since the effects of the CMV can be more severe in wide bandgap (WBG) and high switching frequency-based converter systems, various methods have been proposed to mitigate the CM noise issues. This work presents a multi-level inverter system composed of a multi-level inverter with a proposed multi-level active power filter (APF). For attenuating the CMV in multi-level inverters using multi-carrier-based PWM methods, a novel PWM method is presented for the proposed multi-level APF. The three-phase five-level active-neutral-point-clamped (ANPC) II-type inverter using the apparent switching frequency doubling (ASFD) PWM is used as an example of the multi-level inverters and carrier-based PWM methods to analyze and verify the proposed CMV attenuation method. The APF generates and injects the APF voltage equal to the CMV to attenuate the CM noise accurately. Various key challenges, including the dead-time compensation, are addressed through the proposed advanced PWM techniques to improve the CMV attenuation performance. Simulation and experimental results are provided to verify the comparison and effectiveness of the proposed CMV attenuation method.

An Advanced PWM Technique for MMC Inverter Based Grid-Connected Photovoltaic Systems

Recent developments in multilevel inverters have provided impetus for their applications in the medium voltage renewable energy generation processes. This paper proposes an advanced pulse width modulation technique for a modular multilevel cascaded (MMC) inverter based grid integrated solar photovoltaic (PV) system. It offers lower total harmonic distortion (THD) and power losses compared to the existing modulation techniques. This paper shows the design and performance evaluation of the proposed technique using a 3-phase 5-level MMC inverter-based grid connected PV system. The proposed PWM technique offers 12.49% (without filter) and 0.96% (with filter) output line voltage THDs. It also offers 4.64% output current THD, which complies with the IEEE-519 standard for grid integration. Besides THD reduction, it also reduces the switching and conduction power losses of the MMC inverter. Lower losses may help to keep device temperature low, which is essential for power converters used in superconducting magnetic energy storage (SMES) systems. The simulation is performed in MATLAB/Simulink and the proposed technique is experimentally validated with a laboratory test platform.

An Effective Energy Management With Advanced Converter and Control for a PV-Battery Storage Based Microgrid to Improve Energy Resiliency

This article presents an energy management strategy for a microgrid having solar PV arrays and a battery energy storage system (BESS). Most of the energy management strategy used for commercial photovoltaic (PV) inverters and battery inverters do not consider the future load behavior and cannot ensure the energy resiliency for a PV and battery storage based microgrid. This article proposes the use of a model predictive control strategy that considers future load behavior and energy cost profile to determine an optimum power flow trajectory to achieve energy resiliency, minimize the operating cost and maximize the profit of the microgrid. The proposed control strategy of the energy management system (EMS) is validated using both simulations in MATLAB/Simulink environment and by carrying out laboratory experiments on a developed laboratory test platform. For the converters of the test platform, this article develops a magnetically linked seven-level multilevel converter (acting as the solar PV inverter) and a full-bridge inverter with an advanced pulsewidth modulation technique (acting as the BESS inverter). Commercial inverters usually require large and bulky power frequency transformers for the grid integration of renewable energy sources. The high-frequency magnetic link-based power electronic converter can produce multiple balanced dc power sources with reduced size, ensures lower power losses during the energy conversion process and can also ensure galvanic isolation. The results from the simulation and experimental studies of the EMS demonstrate that the developed energy management strategy ensures both the minimization of the operating cost of the system and the increased resiliency of the whole system.

A New Generalized Step-Down Single-Stage AC/AC Power Converter

Most traditional AC/AC power converters suffer from power quality problems and multi-stage power conversion losses. The rectifier and inverter-based AC/AC converter topology not only increases multi-stage power conversion losses, but also increases the volume, weight, and cost, and decreases the longevity of the converter due to the DC-link capacitor, line filter and electromagnetic interference (EMI) filter. High-frequency (about 10 kHz) switching advanced pulse width modulation techniques are generally used in order to compensate the power quality problems, which increase the switching losses and introduce the EMI problems. In this paper, a new generalized step-down single-stage line-frequency switching AC/AC power converter topology is proposed. The proposed converter uses line-frequency switching, and does not require any pulse width modulation techniques. The proposed topology offers promising performances in terms of lower order harmonics, total harmonic distortion, the elimination of DC-link capacitors and EMI filters, and switching losses. The circuit was designed and simulated in a MATLAB/Simulink environment. A scaled-down laboratory prototype of the proposed topology was developed in order to validate the feasibility. The experimental and simulation results reveal the feasibility of the proposed generalized step-down single-stage converter topology, and its excellent features.

Intrinsic Power Management Strategy based improvement of power stability in a single-phase AC–DC converter system

Nowadays the size of the use of electronic devices like laptops, cell phone chargers, electric vehicles and UPS is rapidly increasing. So AC–DC converters need to incorporate the power factor correction along with voltage regulation. There are many AC–DC converter control methods available, but these methods do not perform well. Therefore In this paper, a smooth transformation on switching will be characterized by a high power factor in a single phase AC–DC converter by the use of intrinsic power management strategy. The proposed AC–DC converter's circuit topology is obtained by integrating a boost and buck converter. The Boost Converter's switching frequency does power factor correction to get less current harmonics at the input line. In this single phase AC–DC converter, the buck-boost converter is an important component that increases system power quality based on advanced PWM technique. So in this work, the Intrinsic Power Management Strategy (IPMS) is proposed to enhance the control over the DC–DC converter performance during unstable or transient operation. Rather than making a quick Pulse Width Modulation (PWM) signal, the computerized signal processor just creates a moderate changing DC signal to decide the PWM ramp function. The power factor correction model has been created and simulated by utilizing MATLAB programming. The simulation model demonstrates that the power factor is improved and the converter has regulated DC output voltage. To validate this simulation, a 1000 W prototype converter has been developed to feed a DC motor and the analysis of the results are presented.

Three-Vector-Based Low-Complexity Model Predictive Direct Power Control Strategy for PWM Rectifier Without Voltage Sensors

A voltage sensorless control of low-complexity model predictive direct power control (LC-MPDPC) for pulsewidth modulation (PWM) rectifier is proposed. The conventional LC-MPDPC adopts one or two voltage vectors during one control period, which achieve good steady-state performance and quick dynamic response. In addition, based on the mathematical model of the real system, the conventional method only requires one prediction to find the optimal voltage vector, which reduces the control complexity and computational burden. However, the use of one or two vectors during one sampling interval presents abundant current harmonics and high power ripples, and the switching frequency is variable. In order to solve these problems while preserving all the advantages of the conventional LC-MPDPC, this paper presents a novel control scheme, with the aim of operating at a constant switching frequency and obtaining an excellent steady-state performance at a low switching frequency. The proposed method is based on an optimal application of three voltage vectors in a symmetrical way, which takes advantage of advanced PWM techniques. Furthermore, the virtual flux-based control scheme is introduced to achieve voltage sensorless control. The proposed strategy is compared with the conventional MPDPC methods and its effectiveness is confirmed by both simulation and experimental results from a three-phase PWM rectifier under 1000-W operation condition.

Space-Vector based Advanced Pulse Width Modulation Techniques for Z-Source Inverter

Space-Vector based Advanced Pulse Width Modulation Techniques for Z-Source Inverter

Investigation of single phase reduced switch count asymmetric multilevel inverter using advanced pulse width modulation technique

In this paper, a new topology for Multilevel Inverter (MLI) with reduced switch count is proposed with an asymmetric dc source configuration. This configuration is used to double the output voltage level in multilevel inverter based on switched dc sources, by adding two switches with dc sources. The increased number of levels in the output voltage reduces the filtering requirements. The working principle of the proposed asymmetric inverter is presented through the single phase fifteen level inverter. The harmonic contents of different modulation indices are examined. The performance analysis of the inverter is compared with trapezoidal and Sinusoidal Pulse Width Modulation (SPWM) in terms of Total Harmonic Distortion (THD), fundamental rms voltage (V rms ) and Crest Factor (CF). The simulation results for the same are evaluated using MATLAB/SIMULINK

Real Coded Genetic Algorithm Based Improvement of Efficiency in Interleaved Boost Converter

<table width="593" border="1" cellspacing="0" cellpadding="0"><tbody><tr><td valign="top" width="387"><p> The reliability, efficiency, and controllability of Photo Voltaic power systems can be increased by embedding the components of a Boost Converter. Currently, the converter technology overcomes the main problems of manufacturing cost, efficiency and mass production. Issue to limit the life span of a Photo Voltaic inverter is the huge electrolytic capacitor across the Direct Current bus for energy decoupling. This paper presents a two-phase interleaved boost converter which ensures 180 angle phase shift between the two interleaved converters. The Proportional Integral controller is used to reshape that the controller attempts to minimize the error by adjusting the control inputs and also real coded genetic algorithm is proposed for tuning of controlling parameters of Proportional Integral controller. The real coded genetic algorithm is applied in the Interleaved Boost Converter with Advanced Pulse Width Modulation Techniques for improving the results of efficiency and reduction of ripple current. Simulation results illustrate the improvement of efficiency and the diminution of ripple current.</p></td></tr></tbody></table>

Investigation of single phase reduced switch count asymmetric multilevel inverter using advanced pulse width modulation technique

Investigation of single phase reduced switch count asymmetric multilevel inverter using advanced pulse width modulation technique

PWM Chopper of Ultrasonic Power Supply Based on FPGA

Pulse width modulation (PWM) is often one of the important power regulation method of ultrasonic power supply. The traditional PWM control circuit has the shortcomings of complex design structure, slow dynamic response and low reliability. An advanced PWM technique for choppers of ultrasonic power supply based on FPGA is proposed. Through open-loop operation, it regulates the output pulse width of ultrasonic power supply dynamically. The simulation result shows that the PWM control circuit based on FPGA can realize to adjust the width of PWM signal and power regulation conveniently.

Compatibility Issues Between the Filter and PWM Unit in Three-Phase AC Motor Drives Utilizing the Pure Sine Filter Configuration

Inserted between the inverter and the ac motor for the purpose of providing clean sinusoidal voltage at the motor terminals, the pure sine filter (PSF) involves common-mode and differential-mode suppression components. When using PSF in a motor drive and employing advanced pulsewidth modulation (PWM) techniques with discontinuous modulation waveforms, a large common-mode current may circulate through the inverter and the filter resulting in overcurrent stress in the inverter and significant acoustic noise in the filter inductors. This paper first discusses the PSF and advanced PWM techniques, then investigates the performance issues that may arise when combining advanced discontinuous PWM methods with PSF and provides a curement for the overcurrent stress problems by means of a rate of change limiter. The simulations and detailed experimental studies illustrate the inverter overcurrent stress problems and the feasibility of the proposed method to cure the problems. Via experimental performance evaluation of various PWM methods, the paper also suggests, along with PSF, the use of advanced continuous and discontinuous PWM methods with reduced common-mode voltage for the purpose of performance enhancement and filter size reduction.

Development of a high-speed, magnetically-loaded energy storage system

Williams Formula One (WF1) is one of the world's leading racing teams and has pioneered many technological innovations for racing cars in the past thirty years. Williams Technology Centre (WTC) is a recently formed company that is focused on exploiting one of the technologies WF1 has been nurturing for hybrid automotive applications, flywheel storage. WTC business objectives are; the advancement of a cost-effective energy storage and power delivery pack to boost performance and improve efficiencies across multiple industries such as transportation, telecommunications, renewable energy, industrial, and aerospace. Applications of energy storage technology will lead to a reduction of fuel consumption, greenhouse emissions and improvement in system efficiency. The enabling technologies for the WTC power pack are a magnetically loaded composite (MLC) rotor and a power electronics inverter (PEI). MLC is formed by mixing magnetic particles into a carbon based matrix filament. Glass and carbon fibres are added to the MLC layer to provide mechanical stability at high speed operation. The rotor is magnetized into a Halbach arrangement to eliminate back iron and generate a sinusoidal field distribution in the air gap. Another key enabling technology that will be developed by WTC is the power electronics inverter. The inverter will regulate the machine input/output using advanced pulse width modulation techniques. Advanced motor control strategies are currently being investigated to maximise system efficiencies and robustness in case of faults. Supported by a Qatar Foundation grant, WTC is currently building an engineering design office and electronic and mechanical engineering workshop to advance the development of a high power/energy flywheel. Efforts are ongoing to employ key specialists and development engineers to work on components and system engineering issues. The full paper will discuss the key features of the flywheel technology and compare its performance against other technologies like super capacitors and lithium ion batteries. The paper will also review the ongoing engineering effort and technical advances necessary to support prototype/product development. Assessment of typical markets and applications will also be discussed.