In order to perform more accurate high-altitude bench tests for aero-engines,a control strategy with high dynamic performance is proposed for energy feedback type electronic loads. The continuous control set model predictive control (CCS-MPC) enables the predicted current to quickly track the reference current and improves the dynamic performance of the system. Meanwhile, A Kalman observer is designed to solve the model mismatch problem of the system due to inaccurate circuit parameters and measurement errors by optimizing the estimation of input voltage and inductor currents in each phase. In addition, in order to prevent the peak current from being too high and causing excessive shock to the system, current limiting control is proposed. When the output duty cycle is too large resulting in too high a current, another duty cycle is output by modifying the MPC objective function to achieve current limiting. Finally, the feasibility and effectiveness of the proposed control is verified by simulation.

This article proposes a photovoltaic (PV)-storage three-port converter (TPC), which achieves power balancing among three ports by multiplexing six switches, offering flexible power flow control with five operating modes. A four-target control strategy that can achieve PV maximum power point tracking (MPPT), output voltage stabilization, and secondary ripple suppression at the two DC ports is proposed. Through power decoupling, the secondary ripple of the two DC ports is transferred to the bus capacitor, thereby achieving suppression of the ripple. Besides, theoretical analyses of the circuit topology and switching state, control strategy, steady-state characteristics, and high-frequency switching processes are conducted in turn. Based on this, an experimental setup was built to experimentally validate the functionality of the converter. Experimental results demonstrate that the converter can operate effectively under both three-port and two-port status, achieving PV MPPT and two DC ports secondary ripple suppression at the same time, while delivering high-quality AC voltage, showcasing excellent overall performance.

ABSTRACT To achieve flexible power flow allocation in distributed generation applications, an isolated dual‐active‐bridge (DAB) three‐port converter based on model predictive control (MPC) is proposed. By managing bidirectional power flow at the battery port, the converter maintains power balance among the photovoltaic (PV), battery, and load ports, with five operating modes. To extend the soft‐switching range and reduce computational complexity, an extended phase‐shift (EPS) modulation strategy with three degrees of freedom is introduced. Furthermore, a hybrid multi‐loop control strategy integrating PI and MPC is designed to coordinate inter‐port power management and enhance overall system performance. A theoretical analysis of the circuit topology, power transfer characteristics, modulation strategy, and control strategy is presented sequentially. Finally, an experimental setup is developed to validate the performance of the proposed converter under the designed control strategy. Experimental results demonstrate that the converter effectively achieves maximum power point tracking (MPPT) at the PV port and provides a stable output voltage, with the voltage THD at the AC port below 2.2%, indicating excellent steady‐state performance.

To address the pollution problem caused by unbalanced nonlinear loads on the grid, this paper proposes a modular multilevel converter-based active power filter (MMC-APF) for optimal composite control of compensation currents based on multi-step model prediction. The compound control of PI and repetitive control (RC) is used to obtain the number of bridge arm pre-conductor sub-modules. On this basis, the multi-step model predictive control is used to narrow the search range for finding the optimal level of the objective function. There is no need to design the weighting factors, and the total number of sub-modules put into per phase bridge arm is [N−1, N+1], which can achieve 2N+1 maximum level number output, enhancing the MMC-APF AC side current tracking accuracy and improving the system dynamic performance. Meanwhile, a grouped hierarchical voltage equalization modulation strategy based on the predicted values of sub-module capacitance voltages is proposed, reduces the computational complexity of the equalization process, and lowers the switching frequency of sub-modules. Finally, the MMC-APF platform is built to verify the effectiveness of the proposed research scheme.

This paper proposes a single-stage three-port isolated H-bridge inverter. Five operating modes and five switching equivalent circuits of the inverter are studied, and three H-bridge three-phase-shift modulation strategy and multi-loop energy management control strategy are proposed to achieve the maximum power tracking of the photovoltaic cells, at the same time, the energy flow and power balance between the three ports of photovoltaic, battery and load are realized by reasonably controlling the charging and discharging of the battery, so as to ensure the continuous and stable power supply of the system to the load. The circuit topology, operation modes, switching equivalent circuits, phase-shift modulation strategy and control strategy, and circuit parameter design of the inverter are also theoretically analyzed. On this basis, a single-stage three-port isolated H-bridge inverter experimental prototype is designed and developed, and the experimental results verify the feasibility and correctness of the proposed topology and control strategy.

It is difficult to take into account the second-order current ripple, common-mode (CM) current, and efficiency of the converter in the application of vehicle-to-grid (V2G). To address this issue, an asymmetric full-bridge dc-ac converter is presented in this article, which can realize single-stage conversion by multiplexing switches and suppress CM current from the topology principle. A dual-target control strategy for this converter is proposed to implement bidirectional power transmission and power decoupling. Through power decoupling the dc port secondary ripple is transferred to the dc bus capacitor voltage. Besides, the circuit topology, control strategy, operation principle, high-frequency switching process, key circuit parameters design, and losses are analyzed theoretically. A 250 W prototype is built to verify the theoretical analysis. Based on the experimental results, the efficiency is 92.21% while the secondary ripple current of dc port is less than 3% and the common mode leakage current is almost zero at rated power. Finally, the proposed converter system is compared with other research solutions, and the experimental results indicate that the converter system has the optimal comprehensive performance.

The low frequency ripple of the input side current of the single-phase inverter will reduce the efficiency of the power generation system and affect the overall performance of the system.Aiming at this problem, this paper proposes a two-modal modulation method and its MPC multi-loop composite control strategy on the circuit topology of a single-stage boost inverter with a buffer unit.The control strategy achieves the balance of active power on both sides of AC and DC by controlling the stable average value of the buffer capacitor voltage, and provides a current reference for inductance current of the DC input side.At the same time, the MPC controller uses the minimum inductor current error as the cost function to control inductor current to track its reference to achieve low frequency ripple suppression of the input current.In principle, it is expounded that the inverter using the proposed control strategy has better low frequency ripple suppression effect than the multi-loop PI control strategy, and the conclusion is proved by the simulation data.Finally, an experimental device of a single-stage boost inverter using MPC multi-loop composite control strategy is designed and fabricated, and the experimental results show that the proposed research scheme has good low frequency ripple suppression effect and strong adaptability to different types of loads.

A novel magnetically-coupled energy storage inductor boost inverter circuit for renewable energy and the dual-mode control strategy with instantaneous value feedback of output voltage are proposed. In-depth research and analysis on the circuit, control strategy, voltage transmission characteristics, etc., providing the parameter design method of magnetically-coupled energy storage inductors and output filter. The circuit topology is cascaded by the input source V-in, the input filter C-in, a single-phase inverter bridge with a magnetically-coupled energy storage inductor, and a CL filter; The control strategy serves the output voltage as a reference to achieve the switch of step-down and step-up modes smoothly. The simulation results of a 1000 VA 100-200 VDC, 220 V 50 Hz AC inverter show that the proposed inverter can realize single-stage boost power conversion, which can adapt to resistive, capacitive and inductive loads, has high power density and low output waveform distortion. It has good application prospects in small and medium-capacity single-phase inverter occasions with low input voltage.

为了实现单级升压逆变,提出了一种带有源缓冲的单级单相电流型PWM逆变器,及其状态量限定下的输出电压反馈复合单周期控制策略,并对构成这种逆变器的电路拓扑、控制策略、关键电路参数设计、系统建模和仿真等进行了深入分析和研究,获得了重要结论.该逆变器电路拓扑主要由储能电感、有源缓冲电路、电流型单相逆变桥构成,存在三种工作模式和四种电路模态,通过三种工作模式的灵活切换达到限定储能电感电流和缓冲电容电压等状态量的目的,通过前馈储能电感电流和反馈输出电压的复合单周期控制实现输出正弦电压的稳定.1 kVA 100 V DC/220 V 50 Hz AC逆变器的原理实验结果表明,所提出逆变器能实现单级升压逆变,具有输出电压波形质量高、负载适应能力强和动态性能好的优点.

In this paper, a new bidirectional DC-AC converter is proposed. The circuit topology of this converter mainly consists of a battery, DC-side filter, energy storage inductor, bus capacitor, asymmetric inverter bridge, AC-side filter and grid, and four circuit modes exist during normal operation. For the application of V2G, a dual-target control strategy is proposed for the converter that can realize bidirectional power transfer and power decoupling, and its circuit topology, control strategy, operating principle and key circuit parameters design are analyzed and studied in depth. The simulation results show that the proposed converter can realize single-stage bi-directional power transfer, with the advantages of simple circuit topology, high quality of grid-connected current waveform and low frequency pulsation of DC-side battery current, which provides a practical new solution for V2G technology.

This paper presents a single-stage three-phase large boost ratio current-type PV grid-connected inverter based on space vector pulse width modulation and its two-loop control strategy with feedback of input-side PV current and output-side grid-connected current, and analyzes and studies the circuit topology that constitute this inverter, space vectors corresponding to circuit modes, modulation strategy, control strategy, design of key circuit parameters, and simulation. The inverter mainly consists of an energy storage inductor with a center tap, a current-type three-phase inverter bridge and output CL filter. The 110VDC/380V 50Hz 3φAC inverter is designed, and the simulation results show that the inverter has the advantages of strong boost capability and low harmonic content of grid-connected current.

升压型逆变器具有单级升压能力、负载短路时可靠性高、系统寿命较长、在光伏场合下可通过控制输入侧储能电感电流实现从弱光能至强光能全过程利用等特点,但传统单级单相升压型逆变器在降压区间储能电感无法去磁,导致输出波形畸变严重.针对这一问题,国内外学者对单级单相升压型逆变器展开了部分研究工作.本文论述了基于传统电路拓扑提出改进控制策略的单级单相升压型逆变器和新颖的单级单相升压型逆变器电路拓扑及其控制策略,并将上述各研究方案的电路参数及性能指标进行对比分析,得出了结论.

磁性元件的设计较为依赖经验公式和方法,设计结果通常具有一定的不确定性.针对大升压比DC/DC变换器提出了利用占空比、升压比和电流突变量三者之间的约束进行估算抽头储能电感关键参数的设计方法,提出了Maxwell电磁场仿真和Psim电路仿真相结合的抽头储能电感绕制方案的寻优.仿真结果表明,所估算的理论参数正确,通过仿真能获得变换器在使用不同绕制方式下电感产生的不同系统性能参数,方便设计者根据实际需求来寻找最合适的制作方案.

In power converter, the system model has a significant meaning of the design of the controller and the dynamic characteristics. In this paper, the switching network average method is used to set up the small signal model of flyback circuit, which is operating in discontinuous current mode(DCM). A controller with single zero and single pole is designed based on the small signal model which is set up in this paper. Moreover, the analysis of system stability and dynamic response is proposed. Finally, the system is simulated and verified by a flyback LED constant current drive circuit (220AC input, 0.7A/16W output).

The design and manufacture of magnetic components such as inductors need to estimate theoretical parameters based on the working characteristics of circuit on the one hand, and select the magnetic core and winding method by experience to determine the manufacturing plan. The parameters and performance of magnetic components obtained by different winding methods are usually different, so the design results have certain uncertainty. In order to better obtain system indicators, a design method for the design of the tapped inductor of large step-up ratio DC/DC converter is proposed to calculate the key parameters such as the turn ratio and inductance of the tapped inductor. The optimized winding scheme method of the tapped inductor is proposed by combining electromagnetic field simulation and circuit simulation. The simulation results show that the theoretical parameters obtained under the proposed method are correct, and multiple performance indicators of the tapped inductance corresponding to the converter circuit under different winding modes can be obtained, which is convenient for the designer to find the best appropriate production plan according to actual needs.

单相逆变器输入侧往往存在低频脉动电流,需要利用很大的电解电容进行滤波,为了取得更好的滤波效果并减小滤波电路参数,有必要采用功率解耦技术解决低频纹波抑制问题.目前文献报道的单相逆变器低频纹波抑制方法大致分为5种情况:DC级功率解耦、两级式功率解耦、AC级功率解耦、三端口功率解耦和无电解电容功率解耦.本文从电路拓扑、电路参数、解耦效果和控制策略几个方面展开介绍,并对以上几种技术进行了比较和评估,总结各功率解耦技术的优缺点及适用范围.

Based on the analysis of the inherent defects of the traditional single-phase current mode pulse width modulation(PWM) inverter, multiple solutions of the defects from aspects of the circuit topology and control strategy are systematically discussed, the design instance and are provided, and important conclusions are obtained.The solutions of circuit topology including such as differential bidirectional Boost DC-DC converter mode inverter, combined Boost/Buck/Buck-Boost inverter, and the single-phase current mode high frequency link inverter with additional flyback AC-DC energy feedback circuit has the characteristics of Boost converter control law, complex circuit, large loss, etc; the solutions of control strategy including such as nonlinear modulation control strategy with compensation link, passive control strategy has the characteristics of high quality of output waveform, large energy storage inductor, etc; the solutions of circuit topology and control strategy including such as the single-phase current inverter with the resonators in serial and parallel of input side, nonlinear PWM one-cycle controlled single-phase current mode inverter with limited energy storage inductor current has the characteristics of high quality of output waveforms, small energy storage inductor, and high conversion efficiency, etc.

Based on the analysis of the inherent defects of the traditional single-stage single-phase boost mode inverter,this paper proposed a novel single-stage single-phase boost mode of photovoltaic (PV) grid-connected power generating systems.The technologies such as circuit topologies with an additional energy storage inductance bypass switch,two kinds of switching modes with energy storage inductance current limited,the nonlinear PWM one-cycle control strategy,energy storage inductance current limits,the switch state equivalent circuit and operating modes within one low frequency output period,design of main circuit parameters,system modeling analysis were carried on the thorough theoretical analysis,and the research conclusions were obtained.The additional bypass switch and its two kinds of switching methods solve the problem of too much energy of the energy storage inductor and decrease effectively the value of the energy storage inductor and its current.Through sampling and feeding back the inverting bridge modulation currents in real-time,the nonlinear PWM one-cycle control strategy adjusts the regenerating energy duty ratio of the inverter,which makes the average value of the output current of the inverter bridge in each switching period to track the reference sinusoidal signal in order to obtain high quality grid-connected current waveforms.The experimental results of the designed and developed 1kVA 110V/DC-220W50Hz prototype have conformed the feasibility of the proposed topology and control strategy,which provides an effective method for single-stage boost medium and small capacity grid-connected power generating fields.

论述了单相Boost型并网逆变器的电路拓扑、工作模态和两种正弦脉宽调制(SPWM)控制策略,深入研究了改进SPWM控制单相Boost型并网逆变器存在的储能占空比与电压传输比不平衡引发的现象,以及基于调制函数推导了逆变器储能电感电流的交、直流分量与电路参数之间的关系,揭示了该逆变器存在储能电感值大、储能电感电流大、输出并网电流波形畸变严重、变换效率低等固有缺陷的机理.提出一种新颖的单相Boost型SPWM并网逆变器,仿真和实验结果证实了理论分析的正确性.

A nonlinear pulse width modulation-controlled single-phase boostmode photovoltaic grid-connected inverter with limited storage inductance current is proposed in this paper. The circuit topology, control strategy, steady-state principle characteristic, and design criterion for the key circuit parameters of this kind of inverter are investigated in depth, and important conclusions are obtained. The inverter's regenerating energy duty ratio 1-D which decreases with the decline of the grid-connected voltage is real time adapted by sampling and feeding back the inverting bridge modulation current, and the average value of the modulation current in each switching cycle tracks the reference sinusoidal signal to get high-quality grid-connected current. The active control of the energy storage inductance current and the balance of the voltage step-up ratio are realized by adding a bypass switch connected in parallel with the energy storage inductance and using two kinds of switching pattern namely boost pattern and freewheeling pattern. The theoretical analysis and experimental results of the 1 kVA 110 VDC/220 V50 Hz photovoltaic grid-connected inverter prototype show that it has the advantages such as single-stage boost conversion, high conversion efficiency, high quality of grid-connected current waveform, low value of energy storage inductance, simple control, etc.