Design and implementation of FPGA-based phase modulation control for series resonant inverters

Owing to the tremendous advances in the digital technology, and improved reliability and performance of the digital control mechanisms, this paper focuses on design and implementation of digital controller using FPGA-based circuit design approach. The digital controller proposed is designed for series resonant inverter used in DC-DC converter applications. Phase modulation technique is proposed for the realization of digital controller on FPGA. The Series Resonant Converter (SRC) is considered in this paper as a preferred converter topology for high power, high voltage power supplies. This paper studies the implementation of phase shift modulation technique using FPGA. The inverter designed, is IGBT based, and Zero Voltage Switching (ZVS) technique is implemented due to reduced stresses on devices and increased efficiency. The phase modulated series resonant inverters (PM-SRC) promotes ZVS operation when its switching frequency is greater than resonant frequency. The designed PM controller is realized using FPGA on which control algorithm and other features of a controller are developed. The series resonant inverter is built and tested for full load under open loop and closed loop conditions at a switching frequency of 20 kHz. The results are presented under varying load conditions. The simulation and the experimental results were found to match closely.     

Feedforward simple control technique for on-chip all-digital three-phase AC/DC power-MOSFET converter with least components

A novel simple control technique for on-chip all-digital three-phase alternating current to direct current (AC/DC) power-metal oxide semiconductor field-effect transistors (MOSFET) converter with least components, which is employed to obtain small current and DC output voltage ripples as well as excellent performance, and using a feedforward simple control method for DC output voltage regulation is proposed. The proposed all-digital feedforward controller has the features of low cost, simple control, fast response, independence of load parameters and the switching frequency, it has no need for compensation, and high stability characteristics; moreover, the proposed controller consists of three operation amplifiers and few digital logic gates that are directly applied to the three-phase converter. The power-MOSFETs are also known as power switches, whose control signals are derived from the proposed all-digital feedforward controller. Instead of thyristors or diodes, the application of power-MOSFETs can reduce the loss of AC/DC converter that is proper to the power supply system. The input stage of an AC/DC converter functions as a rectifier and the output stage is a low pass inductor capacitor (LC) filter. The input AC sources may originate from miniature three-phase AC generator or low-power three-phase DC/AC inverter. The maximum output loading current is 0.8 A and the maximum DC output ripple is less than 200 mV. The prototype of the proposed AC/DC converter has been fabricated with Taiwan Semiconductor Manufacturing Company (TSMC) 0.35 mum 2P4M complementary MOS (CMOS) processes. The total chip area is 2.333 1.960 mm². The proposed AC/DC converter is suitable for the following three power systems with the low power, DC/DC converter, low-dropout linear regulator and switch capacitor. Finally, the theoretical analysis is verified to be correct by simulations and experiments.     

5kW弧电源的设计与仿真

介绍了开关电源的优点和大功率弧电源的结构,给出了以SG3525为控制核心的弧电源的设计方法。该电源主电路采用全桥式逆变电路,应用平均电流模式控制的PWM调制技术实现电流的稳定输出。并应用OrCAD15.7仿真工具对主电路和控制电路建模并进行闭环仿真,得到了与设计要求相符合的实验结果,通过对仿真结果的分析验证了设计方案的可行性。试验表明,该弧电源具有良好的性能。     

基于状态空间的PWM逆变器数字PI双环控制技术研究

主要研究了数字控制的实际应用情况以及脉宽调制(PWM)正弦波逆变器的特点,包括电流内环电压外环的双闭环控制。在建立逆变器控制系统状态空间模型的基础上,详细分析了外环为输出电压,内环为电感电流加负载电流前馈控制对应的控制策略的稳定性和动态响应。先对控制系统直接离散化,再利用极点配置的方法进行系统参数设计。从响应速度、外特性、稳定性方面进行了具体分析,结果说明在离散域里双环控制逆变器具有较好的动态响应速度和输出外特性。最后通过实验验证和仿真波形分析,证明这种双环控制技术能满足各项性能指标要求。     

Zero-voltage-switching DC/AC inverter

A novel zero-voltage-switching (ZVS) DC/AC inverter is proposed. The proposed inverter can not only provide output voltage that is higher or lower than DC input voltage but can also use the pulse-width modulation (PWM) control technique. Furthermore, in the proposed inverter, besides operating at constant frequency, all semiconductor devices operate at soft-switching without additional voltage stress and current stress. A design example of 1000 W ZVS-PWM buck-boost inverter is examined to assess the inverter performance     

A Modified-Simplified MPPT Technique for Three-Phase Single-State Grid-Connected PV Systems

Nowadays, the single state inverter for the grid-connected photovoltaic (PV) systems is becoming more and more popular as they can reduce circuit complexity resulting in less power losses of the inverter. This paper focuses on the use of model predictive control (MPC) to control a 3-phase and 2-level single-state grid-connected inverter in order to regulate the PV maximum power point (MPP). The algorithm of MPC scheme was done to measure the simultaneous current signal including predicting the next sampling current flow. The reference current (I_d*) was used to control the distribution of electrical power from the solar cell to the grid. To be able to control the maximum power point tracking (MPPT) when the sunlight suddenly changes, so that a developing MPPT based on estimation current perturbation and observation (ECP&O-MPPT) technique was used to control the reference current. This concept was experimented by using MATLAB/Simulink software package. The proposed technique was tested and compared with the old technique. The simulation results showed that the developed MPPT technique can track the MPP faster when the light changes rapidly under 1,000 W/m², 25°C standard climatic conditions. The MPPT time was 0.015 s. The total harmonic distortion (THD) was 2.17% and the power factor was 1.     

Soft-switching flyback inverter with enhanced power decoupling for photovoltaic applications

A novel single-phase flyback inverter for photovoltaic applications is proposed to achieve low-frequency ripple current reduction on the DC busbar and to draw sinusoidal current into the AC grid. Based on capacitive idling techniques, the proposed circuit topology is derived from a single-ended primary-inductance converter and two-switch flyback inverter to obtain soft-switching operation for all of the active switches. Compared with a buck-boost inverter and other flyback inverter topologies for AC photovoltaic module systems, no extra active switches are used in the proposed inverter to realise both soft-switching and enhanced power decoupling with only four active switches. Peak-current mode control method is employed in the control schemes to ensure pure sinusoidal current with unity power factor on the AC grid. Laboratory experimental results based on a 500 W prototype are provided to verify the effectiveness of the proposed inverter     

Recurrent wavelet neural network controller with improved particle swarm optimisation for induction generator system

A recurrent wavelet neural network (RWNN) controller with improved particle swarm optimisation (IPSO) is proposed to control a three-phase induction generator (IG) system for stand-alone power application. First, the indirect field-oriented mechanism is implemented for the control of the IG. Then, an AC/DC power converter and a DC/AC power inverter are developed to convert the electric power generated by a three-phase IG from variable frequency and variable voltage to constant frequency and constant voltage. Moreover, two online trained RWNNs using backpropagation learning algorithm are introduced as the regulating controllers for both the DC-link voltage of the AC/DC power converter and the AC line voltage of the DC/AC power inverter. Furthermore, an IPSO is adopted to adjust the learning rates to further improve the online learning capability of the RWNN. Finally, some experimental results are provided to demonstrate the effectiveness of the proposed IG system.     

A grid-tie PV inverter with the ability to improve power quality under unbalanced and distorted source voltage conditions

ABSTRACT

This paper proposes a grid-tie PV inverter that is able to improve power quality under conditions of both distorted and unbalanced source voltage. The presented strategy is based on the instantaneous power theory and uses a second-order generalized integrator-quadrature signal generator (SOGI-QSG). The presented control strategy is aimed at compensating reactive power, eliminating current harmonics, load balancing, and enabling the PV to inject maximum power to the grid. The advantages of the control system are the use of SOGI-QSG adaptive filter and frequency-locked loop (FLL), and removing the low-pass filter and phase-locked loop (PLL). DC–DC and DC–AC converters are utilized for connecting the PV to the grid. The DC–DC and DC–AC converters are responsible for maximum PV power tracking and achieving the control aims, respectively. Using 4-leg converter structure for grid-tie inverter enables achieving the control objectives in 3-phase 4-wire distribution network without any transformer. The presented control strategy is applied to a 3-phase 4-wire distribution network and is simulated in MATLAB/SIMULINK environment. The results of this simulation are then compared with the conventional instantaneous power method in areas including load balancing, reactive power compensation and the elimination of current harmonics, under unbalanced and distorted source voltage conditions.     

低调制度下二极管箝位型多电平 逆变器新型PWM控制方法

二极管箝位型多电平逆变器作为一种应用于高压大功率变换场合的变换器,其PWM控制技术是研究的核心内容之一。本文针对已有载波PWM方法中低调制度下电平退化的问题,提出了一种新颖的载波PWM方法,既便是在低调制度下,所有的电平都能够得到应用。仿真结果表明,这种方法可以提高二极管箝位型逆变器在低调制度下的器件利用率,使得逆变器在低调制度下工作于较高频率。     

A single phase photovoltaic inverter control for grid connected system

This paper presents a control scheme for single phase grid connected photovoltaic (PV) system operating under both grid connected and isolated grid mode. The control techniques include voltage and current control of grid-tie PV inverter. During grid connected mode, grid controls the amplitude and frequency of the PV inverter output voltage, and the inverter operates in a current controlled mode. The current controller for grid connected mode fulfills two requirements – namely, (i) during light load condition the excess energy generated from the PV inverter is fed to the grid and (ii) during an overload condition or in case of unfavorable atmospheric conditions the load demand is met by both PV inverter and the grid. In order to synchronize the PV inverter with the grid a dual transport delay based phase locked loop (PLL) is used. On the other hand, during isolated grid operation the PV inverter operates in voltage-controlled mode to maintain a constant amplitude and frequency of the voltage across the load. For the optimum use of the PV module, a modified P&O based maximum power point tracking (MPPT) controller is used which enables the maximum power extraction under varying irradiation and temperature conditions. The validity of the proposed system is verified through simulation as well as hardware implementation.     

交流变频调速系统仿真建模及谐波特性分析

随着电力电子技术的发展,交流变频调速系统以其强大的优势逐渐取代传统的直流调速传动,其在给人们生产生活带来方便和效率的同时,也造成了电力系统谐波污染加重的问题。因此,设计了一种开环正弦脉宽调制（sinusoidal pulse width modulation,SPWM）控制的交流变频调速系统并搭建仿真模型,实现了对系统中变频器输出电压频率和幅值及电机转速的灵活控制。对系统网侧电压和电流进行了谐波特性分析,结果表明：网侧电压的波形比较理想、畸变很小,而电流波形畸变严重;且随着变频器输出频率的增加,电压波形畸变程度有所加剧,电流畸变程度有所减轻。     

Study on the new control scheme of class-E inverter for IH-jar application with clamped voltage characteristics using pulse frequency modulation

A new control scheme of Class-E inverter for induction heating jar applications with clamped voltage characteristics using pulse frequency modulation (PFM) is introduced. To reduce the voltage stress of a switch, the proposed PFM control scheme does not need any auxiliary circuit. It can decrease the voltage stress of a switch through the modulation of switching frequency. The Class-E inverter using the proposed control scheme has the advantages of not only the same output power when it is compared with an active clamped class-E (ACCE) inverter, but also zero-voltage-switching, which are characteristics of conventional Class-E and ACCE inverter. The control principles of the proposed method are explained in detail and its validity is verified through experimental results     

Multiple-load series resonant inverter for induction cooking application with pulse density modulation

Multiple-load induction cooking applications are suitable used when multi-output inverters or multi-inverters are needed for multiple-load operation. Some common approaches and modifications are needed in inverter configuration for multiple-load application. This paper presents an inverter configuration with two loads by using pulse density modulation control technique. It allows the output power control of each load independently with constant switching frequency and constant duty ratio. The pulse density modulation control technique is obtained using phase on–off control between two legs of the inverter to reduce acoustic noise. The two-load three-leg inverter configuration provides reduction of the component count for extension of multiple loads. The control technique provides a wide range of output power control. In addition, it can achieve efficient and stable zero voltage switching operation in the whole load range. The proposed control scheme is simulated and experimentally verified with two-load inverter configuration.     

Vector-optimised harmonic elimination for single-phase pulse-width modulation inverters/converters

A new approach for calculating single-phase inverters/converters-optimised pulse-width modulation (PWM) switching angles for harmonic and voltage control is proposed. This approach takes into account the DC-link voltage ripple, due to the finite DC-link capacitance, in the optimised switching-angles calculation, using its harmonic content. New expressions for the evaluation of the PWM waveform harmonic spectrum are derived. Output voltage quarter-wave symmetry is thus not assumed and the pulse position is no longer fixed, resulting in two simultaneous sets of nonlinear equations in twice as many unknowns as in the case of conventional-optimised PWM strategy with smooth DC input/output voltage. The performance of this latter technique is hence retained while the size of the DC-link capacitor is reduced to a limit depending on the filter capacitance, the number of pulses per half modulation period and the modulation depth. The compensation of the reactive power (exchanged between the AC source/AC load and the DC link due to the rectifying/inverting process and the low-link capacitance) is also included; the converter then plays the additional role of an active power filter. Simulation examples and experimental results are used to validate the proposed method     

Negative sequence compensation within fundamental positive sequence reference frame for a stiff micro-grid generation in a wind power system using slip ring induction machine

An isolated wind power generation scheme using slip ring induction machine (SRIM) is proposed. The proposed scheme maintains constant load voltage and frequency irrespective of the wind speed or load variation. The power circuit consists of two back-to-back connected inverters with a common dc link, where one inverter is directly connected to the rotor side of SRIM and the other inverter is connected to the stator side of the SRIM through LC filter. Developing a negative sequence compensation method to ensure that, even under the presence of unbalanced load, the generator experiences almost balanced three-phase current and most of the unbalanced current is directed through the stator side converter is the focus here. The SRIM controller varies the speed of the generator with variation in the wind speed to extract maximum power. The difference of the generated power and the load power is either stored in or extracted from a battery bank, which is interfaced to the common dc link through a multiphase bidirectional fly-back dc-dc converter. The SRIM control scheme, maximum power point extraction algorithm and the fly-back converter topology are incorporated from available literature. The proposed scheme is both simulated and experimentally verified.     

高性能模糊控制裹包机的感应电动机驱动系统的设计与实现

针对接缝式裹包机的交流调速系统控制精度较差的问题,提出了具有模糊控制器的有限周期控制的感应电动机驱动.由于转矩和磁通是由有限周期控制技术调节,能达到极快转矩响应.将模糊控制器应用于速度控制反馈环节中,使该驱动系统具有高自适应能力,且对参数和工作条件改变是非常的不灵敏.     

混合动力汽车快速控制原型系统仿真平台开发

为加快混合动力汽车控制策略的开发进度,缩短产品开发周期,设计与开发了基于飞思卡尔MC9S12DG256控制器、驾驶员模拟器、控制器自动代码生成编译工具包及Freemaster实时数据监测软件构成的混合动力汽车控制策略快速控制原型系统半实物仿真平台,将底层驱动与上层控制策略模型一键下载到MC9S12DG256控制器,实现模型到代码的自动下载,并能与AVL CRUISE中车辆信息进行实时的串口通信。针对一款并联式混合动力客车进行仿真实验,结果能较好地模拟实车特性,验证了该仿真平台的有效性,其开发成本低廉,易在高校中推广。     

Fuel cell power conditioning for electric power applications: a summary

Fuel cells are considered to be one of the most promising sources of distributed energy because of their high efficiency, low environmental impact and scalability. Unfortunately, multiple complications exist in fuel cell operation. Fuel cells cannot accept current in the reverse direction, do not perform well with ripple current, have a low output voltage that varies with age and current, respond sluggishly to step changes in load and are limited in overload capabilities. For these reasons, power converters are often necessary to boost and regulate the voltage as a means to provide a stiff applicable DC power source. Furthermore, the addition of an inverter allows for the conversion of DC power to AC for an utility interface or for the application of an AC motor. To help motivate the use of power conditioning for the fuel cell, a brief introduction of the different types, applications and typical electrical characteristics of fuel cells is presented. This is followed by an examination of the various topologies of DC-DC boost converters and inverters used for power conditioning of fuel cells. Several architectures to aggregate multiple fuel cells for high-voltage/high-power applications are also reviewed.     

数码涡旋多联机制热控制策略的研究

针对多联机常规的制热控制策略导致系统运行不稳定的特性,提出新的控制策略,建立了压缩机输出比控制模型和压缩机切换控制模型,设计一套10HP数码涡旋多联机系统进行验证.控制模型中以一个周期时间内排气压力的平均值作为当前压力值按照给定的目标压力区域来调节压缩机输出比,并给出了控制模型中的目标压力基准值的确定原则.压缩机切换控制策略中,设置数码压缩机为优先级高的压缩机,调节其输出能力,直到100％输出比,再切换启动定频压缩机,有利于提高性能系数.实验证明这种控制策略对提高系统运行的稳定性、可靠性以及性能系数是可行的.