Model-free Speed Control of Single-phase Flux Switching Motor with an Asymmetrical Rotor

This paper proposes and implements a model-free open-loop iterative learning control(ILC)strategy to realize the speed control of the single-phase flux switching motor(FSM)with an asymmetrical rotor.Base on the proposed winding control method,the asymmetrical rotor enables the motor to generate continuous positive torque for positive rotation,and relatively small resistance torque for negative rotation.An initial iteration coefficient and variable iteration coefficient optimized scheme was proposed based on the characteristics of the hardware circuit,thereby forming the model-free strategy.A series of prototype experiments was carried out.Experimental results verify the effectiveness and practicability of the proposed ILC strategy.

Review of Fault-tolerant Control for Motor Inverter Failure with Operational Quality Considered

In recent years,motor drive systems have garnered increasing attention due to their high efficiency and superior control performance.This is especially apparent in aerospace,marine propulsion,and electric vehicles,where high performance,efficiency,and reliability are crucial.The ability of the drive system to maintain long-term fault-tolerant control(FTC)operation after a failure is essential.The likelihood of inverter failures surpasses that of other components in the drive system,highlighting its critical importance.Long-term FTC operation ensures the system retains its fundamental functions until safe repairs or replacements can be made.The focus of developing a FTC strategy has shifted from basic FTC operations to enhancing the post-fault quality to accommodate the realities of prolonged operation post-failure.This paper primarily investigates FTC strategies for inverter failures in various motor drive systems over the past decade.These strategies are categorized into three types based on post-fault operational quality:rescue,remedy,and reestablishment.The paper discusses each typical control strategy and its research focus,the strengths and weaknesses of various algorithms,and recent advancements in FTC.Finally,this review summarizes effective FTC techniques for inverter failures in motor drive systems and suggests directions for future research.

Review of Three-phase Soft Switching Inverters and Challenges for Motor Drives

For electric vehicles (EVs),it is necessary to improve endurance mileage by improving the efficiency.There exists a trend towards increasing the system voltage and switching frequency,contributing to improve charging speed and power density.However,this trend poses significant challenges for high-voltage and high-frequency motor controllers,which are plagued by increased switching losses and pronounced switching oscillations as consequences of hard switching.The deployment of soft switching technology presents a viable solution to mitigate these issues.This paper reviews the applications of soft switching technologies for three-phase inverters and classifies them based on distinct characteristics.For each type of inverter,the advantages and disadvantages are evaluated.Then,the paper introduces the research progress and control methods of soft switching inverters (SSIs).Moreover,it presents a comparative analysis among the conventional hard switching inverters (HSIs),an active clamping resonant DC link inverter (ACRDCLI) and an auxiliary resonant commuted pole inverter (ARCPI).Finally,the problems and prospects of soft switching technology applied to motor controllers for EVs are put forward.

Indacenodithiophene-based single-component ambipolar polymer for high-performance vertical organic electrochemical transistors and inverters

Single-component ambipolar polymers are highly desirable for organic electrochem-ical transistors(OECTs)and integration into complementary logic circuits with reduced process complexity.However,they often suffer from imbalanced p-type and n-type characteristics and/or stability issues.Herein,a novel single-component ambipolar polymer,namely,gIDT–BBT is reported based on indacenodithiophene(IDT)as the electron donor,benzobisthiadiazole(BBT)as the electron acceptor and oligo ethylene glycol(OEG)as the side chain.Benefitting from the extended backbone planarity and rigidity of IDT,pronounced electron-withdrawing capabil-ity of BBT,favored ionic transport from OEG together with vertical OECT device structure,a nearly balanced ambipolar OECT performance is achieved for gIDT–BBT,revealing a high transconductance of 155.05±1.58/27.28±0.92 mS,a high current on/off ratio>10^(6) and an excellent operational stability under both p-type and n-type operation conditions.With gIDT–BBT in hand,furthermore,vertically stacked complementary inverters are successfully fabricated to show a maximum voltage gain of 28 V V^(-1)(V_(IN)=0.9 V)and stable operation over 1000 switching cycles,and then used for efficient electrooculogram recording.This work provides a new approach for the development of ambipolar single-component organic mixed ionic–electronic conductors and establishes a foundation for the manufacture of high-performance ambipolar OECTs and associated complementary circuits.

Adaptive Predefined-Time Backstepping Control for Grid Connected Photovoltaic Inverter

The system performance of grid-connected photovoltaic(PV)has a serious impact on the grid stability.To improve the control performance and shorten the convergence time,a predefined-time controller based on backstepping technology and dynamic surface control is formulated for the inverter in the grid-connected photovoltaic.The time-varying tuning functions are introduced into state-tracking errors to realize the predefined-time control effect.To address the“computational explosion problem”in the design process of backstepping control,dynamic surface control is adopted to avoid the analytical calculations of virtual control.The disturbances of the PV system are estimated and compensated by adaptive laws.The control parameters are chosen and the global stability of the closed-loop is ensured by Lyapunov conditions.Simulation results confirm the effectiveness of the proposed controller and ensure the predefined time control in the photovoltaic inverter.

A novel cascaded H-bridge photovoltaic inverter with flexible arc suppression function

This paper presents a novel approach that simultaneously enables photovoltaic(PV)inversion and flexible arc suppression during single-phase grounding faults.Inverters compensate for ground currents through an arc-elimination function,while outputting a PV direct current(DC)power supply.This method effectively reduces the residual grounding current.To reduce the dependence of the arc-suppression performance on accurate compensation current-injection models,an adaptive fuzzy neural network imitating a sliding mode controller was designed.An online adaptive adjustment law for network parameters was developed,based on the Lyapunov stability theorem,to improve the robustness of the inverter to fault and connection locations.Furthermore,a new arc-suppression control exit strategy is proposed to allow a zerosequence voltage amplitude to quickly and smoothly track a target value by controlling the nonlinear decrease in current and reducing the regulation time.Simulation results showed that the proposed method can effectively achieve fast arc suppression and reduce the fault impact current in single-phase grounding faults.Compared to other methods,the proposed method can generate a lower residual grounding current and maintain good arc-suppression performance under different transition resistances and fault locations.

Integration of a Fault-Tolerant H-Bridge Inverter into the Photovoltaic System for DC-AC Conversion of Electrical Energy

The photovoltaic system is experiencing great growth in the production of electrical energy these days.It plays a vital role in the production of electrical energy in isolated towns.It is generally either stand-alone or connected to a network.The energy produced by the photovoltaic generator is in continuous form;the conversion from its continuous form to the alternating form requires a converter:the inverter.In order to improve the quality of the waveform,we moved from the classic solar inverter to multilevel inverters.These multilevel inverters are equipped with power switches which are required to withstand strong fluctuations in the voltage produced by the GPV(photovoltaic generator).It is obvious that the degradation of the inverter leads to a distortion of the wave quality.This article presents the simulation of the GPV-Chopper Boost-Inverter chain in fault-tolerant cascaded H-bridges in order to overcome the difficulties of voltage constraints experienced by power switches(IGBT:insulated gate bipolar transistor).The results of simulations carried out in Matlab/Simulink show good performance of the designed inverter model.

An Algorithm for Short-Circuit Current Interval in Distribution Networks with Inverter Type Distributed Generation Based on Affine Arithmetic

During faults in a distribution network,the output power of a distributed generation(DG)may be uncertain.Moreover,the output currents of distributed power sources are also affected by the output power,resulting in uncertainties in the calculation of the short-circuit current at the time of a fault.Additionally,the impacts of such uncertainties around short-circuit currents will increase with the increase of distributed power sources.Thus,it is very important to develop a method for calculating the short-circuit current while considering the uncertainties in a distribution network.In this study,an affine arithmetic algorithm for calculating short-circuit current intervals in distribution networks with distributed power sources while considering power fluctuations is presented.The proposed algorithm includes two stages.In the first stage,normal operations are considered to establish a conservative interval affine optimization model of injection currents in distributed power sources.Constrained by the fluctuation range of distributed generation power at the moment of fault occurrence,the model can then be used to solve for the fluctuation range of injected current amplitudes in distributed power sources.The second stage is implemented after a malfunction occurs.In this stage,an affine optimization model is first established.This model is developed to characterizes the short-circuit current interval of a transmission line,and is constrained by the fluctuation range of the injected current amplitude of DG during normal operations.Finally,the range of the short-circuit current amplitudes of distribution network lines after a short-circuit fault occurs is predicted.The algorithm proposed in this article obtains an interval range containing accurate results through interval operation.Compared with traditional point value calculation methods,interval calculation methods can provide more reliable analysis and calculation results.The range of short-circuit current amplitude obtained by this algorithm is slightly larger than those obtained using the Monte Carlo algorithm and the Latin hypercube sampling algorithm.Therefore,the proposed algorithm has good suitability and does not require iterative calculations,resulting in a significant improvement in computational speed compared to the Monte Carlo algorithm and the Latin hypercube sampling algorithm.Furthermore,the proposed algorithm can provide more reliable analysis and calculation results,improving the safety and stability of power systems.

Reducing Condensation Inside the Photovoltaic(PV)Inverter according to the Effect of Diffusion as a Process of Vapor Transport

A photovoltaic(PV)inverter is a vital component of a photovoltaic(PV)solar system.Photovoltaic(PV)inverter failure can mean a solar system that is no longer functioning.When electronic devices such as photovoltaic(PV)inverter devices are subjected to vapor condensation,a risk could occur.Given the amount of moisture in the air,saturation occurswhen the temperature drops to the dewpoint,and condensationmay formon surfaces.Numerical simulation with“COMSOL Software”is important for obtaining knowledge relevant to preventing condensation by using two steps.At first,the assumption was that the device’s water vapor concentration was homogeneous to evaluate the amount of liquid water accumulated on the internal walls of the photovoltaic(PV)inverter box.Second,by considering the effect of external wind velocity onmoisture transport at the air interface to evaluate water vapor transport outdoors and reduce condensation.General factorial designs are utilized for analyzing the nature of the relationship between the vapor condensation response and the variables.Reducing vapor condensation inside the solar inverter by the effect of external wind speed on diffusion as a process of transporting moister air outside the inverter box is the main solution for this problem.During the movement and assessment of the flow of water vapor,the impact of vapor condensation is reduced.The saturation period was determined by using a Boolean saturation indicator.The saturation indicator was set to 1 when saturation was detected(relative humidity greater than or equal to 1)and 0 otherwise.Calculating the flow and dispersion of moist air as a function of wind speed helped solve the problem.

Estimating the Input Power of a Power Plant Using the Efficiency of the Inverter

The study focuses on estimating the input power of a power plant from available data, using the theoretical inverter efficiency as the key parameter. The paper addresses the problem of missing data in power generation systems and proposes an approach based on the efficiency formula widely documented in the literature. In the absence of input data, this method makes it possible to estimate the plant’s input power using data extracted from the site, in particular that provided by the Ministry of the Environment. The importance of this study lies in the need to accurately determine the input power in order to assess the overall performance of the energy system.

Coordinated Capacitor Voltage Balancing Method for Cascaded H-bridge Inverter with Supercapacitor and DC-DC Stage

Cascaded H-bridge inverter(CHBI) with supercapacitors(SCs) and dc-dc stage shows significant promise for medium to high voltage energy storage applications. This paper investigates the voltage balance of capacitors within the CHBI, including both the dc-link capacitors and SCs. Balance control over the dc-link capacitor voltages is realized by the dcdc stage in each submodule(SM), while a hybrid modulation strategy(HMS) is implemented in the H-bridge to balance the SC voltages among the SMs. Meanwhile, the dc-link voltage fluctuations are analyzed under the HMS. A virtual voltage variable is introduced to coordinate the balancing of dc-link capacitor voltages and SC voltages. Compared to the balancing method that solely considers the SC voltages, the presented method reduces the dc-link voltage fluctuations without affecting the voltage balance of SCs. Finally, both simulation and experimental results verify the effectiveness of the presented method.

Model Predictive Control for Cascaded H-Bridge PV Inverter with Capacitor Voltage Balance

We designed an improved direct-current capacitor voltage balancing control model predictive control(MPC)for single-phase cascaded H-bridge multilevel photovoltaic(PV)inverters.Compared with conventional voltage balanc-ing control methods,the method proposed could make the PV strings of each submodule operate at their maximum power point by independent capacitor voltage control.Besides,the predicted and reference value of the grid-connected current was obtained according to the maximum power output of the maximum power point tracking.A cost function was con-structed to achieve the high-precision grid-connected control of the CHB inverter.Finally,the effectiveness of the proposed control method was verified through a semi-physical simulation platform with three submodules.

Symmetrical dynamical characteristic of peak and valley current-mode controlled single-phase H-bridge inverter

Complex dynamical phenomenon was studied in the single phase H-bridge inverter which was controlled by either a peak current or a valley current. The state functions and the discrete iterative map equations were established to analyze the dynamical phenomenon in the single phase H-bridge inverter. The dynamical characteristics of the single phase H- bridge inverter, such as time domain waveform diagram, bifurcation diagram, and folding map, were obtained by using the numerical calculation when the circuit parameters varied in specific range. Moreover, the simulation results were obtained by using the OrCAD-PSpice software to validate the numerical calculation. Both the numerical calculation and the circuit simulation show that the symmetrical dynamical phenomenon occurs in the single phase H-bridge inverter controlled by the peak current or the valley current.

A 6-switch single-phase 5-level current-source inverter

The new 6-switch single-phase 5-level current-source inverter proposed in this paper was developed by properly simplifying the traditional 8-switch single-phase 5-level current-source inverter, and its operational principle was analyzed. Just like the problem of voltage-unbalance between different levels existing in voltage-source multilevel inverters, a similar problem of current-unbalance between different levels whether for the 8-switch single-phase 5-level current-source inverter, or for the new 6-switch 5-level current-source inverter also exists. A simple current-balance control method via DC current feedback is presented here to implement the current-balance control between different levels. And to reduce the output current harmonics, PWM control technique was used. Simulation and experimental results showed that this new 6-switch topology operates correctly and that the balance-inductor can almost equally distribute the total DC current.

A Novel Single-Phase Five-Level Transformer-less Photovoltaic (PV) Inverter

Multilevel inverters are preferred solutions for photovoltaic(PV)applications because of lower total harmonic distortion(THD),lower switching stress and lower electromagnetic interference(EMI).In order to reduce the leakage current in the single-phase low-power PV inverters,a five-level transformer-less inverter is proposed in this paper.A total of eleven switches are required,while six of them only withstand a quarter of the dc-bus voltage,so the costs for them are low.Another four switches are turned on or off at the power line cycle,the switching losses for them are ignored.In addition,the flying-capacitors(FCs)voltages are only a quarter of the dc-bus voltage,and they are balanced at the switching frequency,which further reduces the system investment.The experimental results based on a 1 kW prototype show that the proposed modulation strategy can balance the FCs voltages at Vdc/4 very well.And the leakage current can be reduced to about 27 mA under both active and reactive operations,which satisfies the VDE 0126-1-1 standard.

Research of Wavelet Modulation for Single-Phase Three-Level Inverter

The single-phase three-level voltage source inverter based on wavelet modulation(WM) is proposed.The WM technique is based on constructing a nondyadic-type multi-resolution analysis(MRA),which supports sampling continuous-time sinusoidal signals in a nonuniform recurrent manner,and then reconstructing it by using inverter switching actions. In order to further improve the output voltage waveform and reduce harmonic distortion,the wavelet modulation is used to three-level inverter. The high magnitude of fundamental component and significantly reduced harmonic contents of the inverter output voltage can be achieved by using WM in the single-phase three-level voltage source inverter. Furthermore,the WM algorithm is implemented by using only one element government(EV) in DSP. The simulated and experimental results prove the accuracy and feasibility of the WM scheme for single-phase three-level voltage source inverter.

Vector Control of the Single-Phase Inverter Based on the Extended and Virtual Circuits

A vector control based on the extended equivalent circuit and virtual circuits is proposed for the single-phase inverter.By the extended circuit,the other two phase voltages can be extended by the output voltage of the single-phase inverter so as to construct the voltage vector.The voltage outer-loop is to control the voltage vector in dq coordinate system,and the output voltage can track the target value without deviation in steady state.By designing the virtual circuit,the voltage inner-loop can achieve approximate decoupling and improve the dynamic response under the changeable load.Compared with the traditional dual closed-loop control,the proposed dual closed-loop control scheme only needs to detect and control the voltage without the current.It not only can achieve good control effect,but also reduce the complexity of the hardware.Finally,the simulation and experimental results show that the single-phase inverter has good static and dynamic characteristics regardless of stable load or changeable load.

A Novel Asymmetrical Single-Phase Multilevel Inverter Suitable for Hybrid Renewable Energy Sources

This paper introduces a novel single-phase asymmetrical multilevel inverter suitable for hybrid renewable energy sources. The proposed inverter consists of two isolated DC sources and six power semiconductor controlled switches. The suggested inverter is capable of generating seven-level output when the input DC voltage is taken in the ratio of 1:2. The higher magnitude DC source is fed from Photo Voltaic (PV) panels, whereas the lower magnitude DC source is fed from Wind Turbine (WT) driven Permanent Magnet DC (PMDC) generator. Both the renewable energy sources are connected to the inverter via two DC-DC boost converters connected in cascade (i.e. one for maximum power point tracking and another for DC-link voltage control). The proposed hybrid renewable energy source inverter is connected to single-phase grid via proper control systems. The complete system is simulated using MATLAB/SIMULINK and the results are presented in detail.

Single-Phase Inverter Synchronized to the Grid by Linear Kalman Filter in Microgrids

This paper presents the analysis and implementation of a synchronizer to the grid using a linear Kalman filter. The synchronizer is used in a single-phase inverter, which is applied in an environment of microgrids. The inverter converts the energy that comes from renewable energy sources （photovoltaic, wind, fuel cell, etc.）. The main objective of obtaining the phase of the grid is to achieve a power factor close to unity in the inverter. For this reason it is vital that the phase difference between the synchronizer and the grid zero. To obtain synchronizer algorithm using LKF （linear Kalman filter） is necessary to know the EKF （extended Kalman filter）. This allows to analyze the operation of the filter, which allows to reach reduce linear Kalman filter or also known as simplified Kalman filter. It is necessary to generate an orthogonal signal in order to obtain a stationary reference frame from a single-phase grid because the linear Kalman filter works with a stationary reference frame. Orthogonal signal is created with an all-pass filter.

Control of Z-Source Inverter Connected to a Single-Phase AC Utility System

This paper presents a single-phase Z-source inverter as a power conditioning system for a single phase utility connected system. Z-source inverter is a single-stage topology that has buck-boost feature, which is possible because of additional shoot through state introduced in zero state of the conventional inverter pulse width modulation and provides desired output AC voltage. Small distributed generation （DG） system with alternate energy sources requires power conditioning units with low cost, high efficiency and tolerance to wide range of input voltage variation and has to perform various functions such as dc-ac conversion, system control and achieve power quality norms. To meet some of these requirements a two-loop control strategy for ac side control with grid current feedback with PI control and inner filter capacitor current feedback with proportional control and on dc side PID control for Z-source capacitor voltage regulation are employed, which gives good transient response also suppress load and source disturbances effectively. Theoretical analysis of proposed scheme is established and then simulation results are presented to validate proposed control strategy.