Mode Power Converters Research Articles

Flexible Arrangement of Static Converters for Grid-Connected Wind Energy Conversion Systems

This paper presents a new flexible arrangement of static converters for grid-connected wind energy conversion systems (WECS). The proposed arrangement uses three-phase voltage-fed back-to-back mass-produced power converter modules with reconfiguration switches. The main features of the proposed flexible arrangement are as follows: 1) expanded reactive power capability limits; 2) high efficiency, mainly under low wind conditions where the active power is reduced; and 3) low current harmonic content. In addition, a detailed description of the operating modes, as well as of the grid, generator, and circulating current controller design, are given. Finally, experimental results support the theoretical development, and demonstrate the good performance and flexibility of the proposed arrangement.

Bi-directional electric vehicle fast charging station with novel reactive power compensation for voltage regulation

Excessive carbon emissions from the current transportation sector has encouraged the growth of electric vehicles. Despite the environmental and economical benefits electric vehicles charging will introduce negative impacts on the existing network operation. This paper examines the voltage impact due to electric vehicle fast charging in low voltage distribution network during the peak load condition. Simulation results show that fast charging of only six electric vehicles have driven the network to go beyond the safe operational voltage level. Therefore, a bi-directional DC fast charging station with novel control topology is proposed to solve the voltage drop problem. The switching of power converter modules of DC fast charging station are controlled to fast charge the electric vehicles with new constant current/reduced constant current approach. The control topology maintains the DC-link voltage at 800V and provides reactive power compensation to regulate the network bus voltage at the steady-state voltage or rated voltage (one per unit). The reactive power compensation is realized by simple direct-voltage control, which is capable of supplying sufficient reactive power to grid in situations where the electric vehicle is charging or electric vehicle is not receiving charges.

직류 배전 시스템을 위한 전력 변환 모듈의 통합 운전

It is DC power that Output of renewable energy being recently developed and researched. Also, demand of DC power will expect to proliferate due to increase of digital load. Thus, DC distribution system providing high quality of power and reliability has emerged as a new distribution system. If the conventional distribution systems are substituted by proposed DC distribution system, the output of renewable energy can be connected with distribution systems under minimum power conversion. Therefore, in the event of connection with DC load, it can construct an efficient distribution system. In this paper, the integrated parallel operation of power conversion module for DC distribution system is proposed. Also, this paper proposed modularization of power conversion devices for DC distribution system and power control for parallel operation of large capacity system. DC distribution system consists of three power conversion modules such as AC/DC power conversion module 2 set, ESS module 1 set. DC distribution system controls suitable operation depending on the status of the DC power distribution system and load. Integrated operation of these systems is verified by simulation and experiment results.

Voltage Synchronization Scheme and Control Strategy for 50 T Flat-Top Pulsed Magnetic Field Power System

At the Wuhan National High Magnetic Field Center (WHMFC), a 100 MJ/100 MVA pulsed generator is used to energize two 12-pulse power converter modules for 50 T flat-top pulsed magnetic field. In this paper, to get a high stability of the magnetic field, a voltage synchronization scheme and a specific control strategy for the power system are designed. Three prime factors which influence the precision of voltage synchronization are analyzed. By using a band-pass filter to smooth out the synchronized line-voltage, a fast response phase locking technique based on zero-crossing detection is adopted to reduce the effects of the above three factors. Then, considering the load characteristics of the 50 T dual-coil magnet about the mutual inductance of two coils and the dramatic increase of the thermal resistance, a no-flat control strategy which could decrease the variation of the firing angle and lower the voltage distortion is employed. By this means, 50 T pulsed field of 100 ms flat-top duration with a ripple of less than 0.5% had been produced, which verified the feasibility of the voltage Synchronization scheme and the control strategy.

Research on Forward DC-DC Converter with High Power

According to the requirements of the aircraft power supply equipment, the high voltage DC-DC power converter module is developed. In this paper, the HVDC (High Voltage DC-DC Converter) topology is studied. The starting circuit is designed based on the control chip TL3844. The components parameters are calculated. An overvoltage protection circuit and a current limiting protection circuit are designed to improve the stability of the system. At the same time voltage compensation circuit is designed to compensate the voltage.

High-Frequency PWM Buck Converters Using GaN-on-SiC HEMTs

GaN high electron mobility transistors (HEMTs) are well suited for high-frequency operation due to their lower on resistance and device capacitance compared with traditional silicon devices. When grown on silicon carbide, GaN HEMTs can also achieve very high power density due to the enhanced power handling capabilities of the substrate. As a result, GaN-on-SiC HEMTs are increasingly popular in radio-frequency power amplifiers, and applications as switches in high-frequency power electronics are of high interest. This paper explores the use of GaN-on-SiC HEMTs in conventional pulse-width modulated switched-mode power converters targeting switching frequencies in the tens of megahertz range. Device sizing and efficiency limits of this technology are analyzed, and design principles and guidelines are given to exploit the capabilities of the devices. The results are presented for discrete-device and integrated implementations of a synchronous Buck converter, providing more than 10-W output power supplied from up to 40 V with efficiencies greater than 95% when operated at 10 MHz, and greater than 90% at switching frequencies up to 40 MHz. As a practical application of this technology, the converter is used to accurately track a 3-MHz bandwidth communication envelope signal with 92% efficiency.

Circuit Designs for an Automation Intelligent Electrical Distribution Terminal Unit Based on DSP

An automation intelligent electrical distribution terminal unit is designed in the paper, making full use of the super calculation ability of digital signal processors. Whole hardware design and circuit designs, such as power conversion module, relay control module communication and data storage module etc, are discussed respectively in the paper. Researches on the reliability of the intelligent terminal unit are carried on finally. Results show that the unit can operate safely, stably and reliably.

The Fully Digital Controlled Corrector Magnet Power Converter with a Shunt as a Current Sensing Component

In Taiwan light source (TLS), Bira’s MCOR30 power converter modules are adopted as the corrector magnet power converters, the output is regulated by analog PWM IC that caused nonlinear behavior at zero cross and the adjustment of compensator for different kind of magnet load is inconvenient. To fulfill digital regulation control, the analog regulation IC of Bira’s MCOR30 is replaced by a fully digital regulation control circuit. With plugging the homemade fully digital regulation control card into MCOR30 that the current sensing component is a shunt that save cost of the power converter, the switching losses and output current ripple were reduced and stability of output current is improved. With the fully digital regulation control circuit, the parameters of the compensator for different magnet load are very easy to adjust. In addition, the feasibility and validity of MOSFET switching algorism is simulated with MATLAB Simulink and the performance of this power converter is verified, the output current ripple of this power converter could be within 10ppm, which is beyond the requirement of current TLS corrector power converter and qualified to be used in the future TPS facility.

Vibration control of resonant vibratory feeders with electromagnetic excitation

The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results.

Cryogenic Power Conversion Systems: The next step in the evolution of power electronics technology

In transportation applications, lower weight and volume of the power conversion systems is very important to achieve high power density, high efficiency, and superior performance. The thermal management of these power conversion units plays a significant role in reducing the weight and volume. The use of superconductive motors/generators, degaussing coils, energy storage modules, and cables has been considered to increase power density and efficiency. High-temperature superconducting (HTS) components combined with cryogenic power converters will provide significant benefits in the electrification of transportation and high power density power conversion systems. Cryogenic power converter modules offer other promising benefits over their room temperature counterparts in terms of reduced size and weight (i.e., increased power density) and improved efficiency, switching speed, and reliability. Such an integration could result in significant weight and space savings for next-generation mass transportation systems. In this article, the current research on cryogenic power electronics and superconducting motors/generators is discussed for future aircraft and ships.

Arranjo Flexível De Conversores Estáticos Para Sistemas De Conversão De Energia Eólica Conectados À Rede


 Este artigo apresenta um arranjo flexível de conversores estáticos para sistemas de conversão de energia eólica (WECS), conectados à rede. O arranjo flexível proposto utiliza módulos conversores trifásicos back-to-back com interruptores auxiliares de reconfiguração. As principais características do arranjo flexível proposto são: (i) expansão dos limites de capabilidade de potência reativa, (ii) alta eficiência, principalmente para condições de baixa velocidade do vento em que a potência ativa é reduzida e (iii) baixo conteúdo harmônico das correntes de saída. Além disso, uma descrição detalhada dos modos de operação, definição das referências de potência, bem como os controladores das correntes do lado da rede, do lado do gerador e correntes circulantes são apresentados. Finalmente, resultados experimentais demonstram o bom desempenho e flexibilidade do arranjo proposto.

Sampled Data Model Predictive Control of a Voltage Source Inverter for Reduced Harmonic Distortion

This brief considers model predictive control of switched mode power converters using a hybrid sampled data model. The goal of the approach is to synthesize a controller that achieves both good dynamic performance and low harmonic distortion at steady state. The suggested control approach takes the switched nature of the converter into account in both the system model and the control objective. This has two main advantages. First, it removes the need for the low-pass filters which are conventionally applied to the state measurements to attenuate the switching ripple. This implies that improved dynamic performance can be obtained. Second, it penalizes the ripple deviation from the reference, which means that reduced harmonic distortion can be obtained at steady state.

The Research on Switch-Linear Hybrid of Precise Current Source

In this paper, a novel current control strategy of precise current source is presented, which combines switch power conversion mode with linear amplification mode. The linear power amplifier is used as the power converter in the current loop. The current controller is a double cascaded PI (DCPI) controller which is put up by the way of analog circuit, it can suppress the high frequency disturbance signal effectively. The switch-filter circuit can generate a special power supply for linear power amplifier, the voltage of this special power supply changes as the load voltage does. The topology of four-level H-Bridge works as the power converter of the switch power amplifier, the LC filter circuit can eliminate the current ripple caused by the PWM chopper.The simulation and experimental results verify that the Switch-Linear Hybrid (SLH) scheme is of high efficiency and output quality. The bandwidth of the precise current source is 5.4 kHz and the phase margin is 42 degree.

Biconical-taper-assisted fiber interferometer with modes coupling enhancement for high-sensitive curvature measurement

A modal interferometer based on multimode- singlemode-multimode fiber structure built with a biconi- cal taper for fiber curvature measurement is proposed and experimentally demonstrated. Due to the tapered single- mode fiber acting as a high-efficient mode power converter to enhance the modes coupling, curvature sensor with improved sensitivity is achieved by monitoring the defined fringe visibility of the interference spectrum. The mea- suring range can be tuned by changing the waist diameter of the fiber taper. Meanwhile, the sensor shows an intrinsic ability to overcome the influence of temperature cross- sensitivity and the power fluctuation of light source. The advantages of easy fabrication, high-quality spectrum with improved sensitivity, and small hysteresis will provide great potential for practical applications of the sensor.

Implementation of a Novel Digital Active EMI Technique in a DSP-Based DC–DC Digital Controller Used in Electric Vehicle (EV)

With ever increasing green-house gas emissions from fossil fuel-driven automobiles leading to acute environmental pollution, and ever depleting reserves of fossil fuel, today need for the development of pure electric vehicle (EV) is of utmost importance. Presently, there is an immense impetus to develop plug-in EVs. High switching frequency and high-power ac-dc PFC converter with an isolated output and a dc-dc isolated converter are essential systems for transferring from utility mains to the different battery packs which store energy for propelling the EVs. Electromagnetic compatibility (EMC) with strict regulatory standards is an essential requirement which any switch mode power converter must comply with not only for its own operation but also for safe and secure operation of surrounding electrical equipment. EVs possess many sophisticated electronic circuits in the vicinity of the battery charging power converters, so strict EMC standards of the on-board power converters should be met. For a cost-effective design approach, EMC should be considered at the primitive stages of the power converter design. The most commonly used passive electromagnetic interference (EMI) filters used for EMI mitigation in power converters come at the expense of cost, size and weight, power losses, and printed circuit board (PCB) real estate. In this paper, a novel embedded digital active EMI filter (DAEF) integrated into the DSP-based digital controller of a dc-dc converter applicable for charging the low-voltage battery bank of an EV is proposed and analyzed. Experimental results and comparison of the performance of the proposed embedded DAEF with a conventional EMI filter are presented in this paper so as to validate the feasibility of the proposed EMI filter and its advantages over the conventional one.

Linear parameter varying control of a doubly fed induction generator based wind turbine with primary grid frequency support

SUMMARYThis paper proposes a control method for a doubly fed induction generator (DFIG) driven by a wind turbine, whose rotor is connected to the power grid via two back‐to‐back pulse‐width modulation power converters. First, we design a rotor current controller for this system using the linear matrix inequality based approach to linear parameter varying systems, which takes into account the nonlinear dynamics of the system. We propose a two‐loop hierarchical control structure. The inner‐loop current controller, which considers the synchronous speed and the generator rotor speed as the components of the parameter vector, achieves tracking of the rotor current reference signals. The outer‐loop electrical torque controller aims for wind energy capture maximization and also grid frequency support, and it generates the reference rotor current. We perform a controller reduction for the inner‐loop linear parameter varying controller, which is not doable by conventional model‐reduction techniques, because the controller is parameter dependent. In simulation, the reduced‐order controller has been tested on a nonlinear fourth‐order DFIG model with a two‐mass model for the drive train. Stability and high performance have been achieved over the entire operating range of the DFIG in the wind turbine. Simulation results have demonstrated the capability of the proposed two‐loop control system to implement also grid frequency support. Copyright © 2013 John Wiley & Sons, Ltd.

Modeling of Switched Reluctance Linear Launcher

A nonlinear simulation model of switched reluctance linear launcher drive based on MATLAB platform is presented in this paper. It consists of a three-phase 6/4 structure simple side switched reluctance linear motor, a three-phase asymmetric bridge power converter, and a closed-loop velocity controller, which is integrated with the magnetization curves of the switched reluctance linear motor obtained by the two-dimension finite-element electromagnetic field calculation, the nonlinear electrical network model of the power converter, and the excitation/commutation/velocity control algorithms. Those include mover relative position calculation module, controller module, power converter module, phase winding modules, and velocity calculation module. The simulated phase current waveforms and velocity curves agree well with the tested phase current waveforms and velocity curves experimentally. It is shown that the proposed nonlinear simulation model of the three-phase 6/4 structure switched reluctance linear launcher system is valid.

Power Management and Charging Method for the Battery-Set of the Intelligent Servant Robot

This paper studies and implements “high efficiency power management system and intelligent battery-set charger system” for “the Intelligent Servant Robot”. This power management system provides high quality and efficiency electric power supply for all subsystems of the servant robot and accurately estimates the residual capacity of battery set system of the servant robot. This servant robot will be charged by the intelligent battery-set charger when the residual capacity of battery sets is insufficient. This servant robot can take the elevator, follow the user, carry articles, and provide the service of campus security patrolling and monitoring. LiFePO4 batteries are chosen as main power supply of the servant robot. The LiFePO4 battery-set system is divided to two subsystems which are the power battery-set (36V/20AH) for motors and the system battery-set (48V/10AH) for PC and MCUs, respectively. High efficiency power management system can measure the basic information (voltage, temperature, and current), provide protection, and give alarm for battery-set system. For the power converter module design of the intelligent battery-set charger, the main structure will use the boost power factor corrector to cascade the full-bridge power converter. The former mainly offers the power input of the high power factor, and the latter adopts the soft-switching and synchronous rectification technology in order to improve its electric conversion efficiency. For the construction of two-stage controllers, the single digital microchip controller is adopted to avoid the interference of high frequency switching of traditional power structure which uses two microchips. The experiment results have demonstrated: 1. the battery-set system can provide over two hour operation of the servant robot continuously. 2. the power management system can accurately estimates the residual capacity of battery set system. 3. the lithium-ion battery protection circuits can cut off the power apply and give the warnings when the battery set is operating under abnormal status. The battery charger allows 110V or 220V input voltage and provides the biggest 20A current to charge battery set. The power battery set can charge up to 90% capacity within one hour.

Modeling, Simulation, and Experiment of Switched Reluctance Ocean Current Generator System

This paper presents nonlinear simulation model of switched reluctance (SR) ocean current generator system on MATLAB/SIMULINK with describing the structure of generator system. The developed model is made up of main model, rotor position calculation module, controller module, gate module, power converter module, phase windings module, flux-linkage module, torque module, and power calculation module. The magnetization curves obtained by two-dimensional finite-element electromagnetic field calculation and the conjugated magnetic energy graphics obtained from the three-dimensional graphics of flux linkage are stored in the “Lookup Table” modules on MATLAB/SIMULINK. The hardware of the developed three-phase 12/8 structure SR ocean current generator system prototype with the experimental platform is presented. The simulation of the prototype is performed by the developed models, and the experiments have been carried out under the same condition with different output power, turn-off angle, and rotor speed. The simulated phase current waveforms agree well with the tested phase current waveforms experimentally. The simulated output voltage curves agree well with the tested output voltage curves experimentally. It is shown that the developed nonlinear simulation model of the three-phase 12/8 structure SR ocean current generator system is valid.

Design and set up of a hybrid power system (PV-WT-URFC) for a stand-alone application in Mexico

The Mexican territory has a large potential for renewable energy development, such as geothermal, hydro, biofuels, wind and solar. Thus, a 2.5 kW hybrid power system (solar, wind and hydrogen) was designed and installed to meet the power demand for a stand-alone application at the University of Zacatecas. The hybrid unit integrates three power energy sources –a photovoltaic system (PV), a micro-wind turbine (WT), a prototype of a unitized regenerative fuel cell (URFC) and energy storage devices (batteries)– in addition to their interaction methodology. The main contribution of this work is the URFC integration to a hybrid power system for the production of H2 (water electrolyzer mode) and energy (fuel cell mode). These three energy technologies were connected in parallel, synchronized to the energy storage system and finally coupled to a power conversion module. To achieve the best performance and energy management, an energy management and control strategy was developed to the properly operation of the power plant. A meteorological station that has wireless sensors for the temperature, the humidity, the solar radiation and the wind speed provides the necessary information (in real time) to the monitor and control software, which computes and executes the short and mid–term decisions about the energy management and the data storage for future analysis.