Hysteresis Band Current Controller

The integration of distributed generation like solar and wind are increasing nowadays due to fossil fuel reduction and increased carbon emission. Many integration issues arise of connecting Solar PV to the grid out of which power quality is the important factor. Higher PV injection causes undesirable technical impacts on the distribution networks which leads to power quality issues. This paper studies the impact of PV on the power quality of the utility grid with different levels of penetration of solar energy into the grid. The power quality of the grid is studied using the Total harmonic distortion (THD) by performing Fast Fourier Transform (FFT) analysis. This paper deals with the development of controllers for boost converter and grid tied inverters which minimizes the harmonics due to solar PV system and power converters in grid connected PV system. The Maximum Power Point Tracking (MPPT) for boost converter and Hysteresis current control (HCC) for inverter has been designed and implemented in grid connected PV system. The hysteresis current controller for the inverter has been specifically designed to reduce the THD of the system meeting IEEE519_1992 regulations. The simulation model of the grid connected PV system has been designed in MATLAB 2018b version. The comparison studies are carried out in the PV system with and without hysteresis current controller, after which it can be concluded that, after the incorporation of the hysteresis current controller, the performance of the system is better in terms of power quality.

In this study, 2.5 kW single-phase pulse-width modulated rectifier is simulated with three different control techniques to investigate the performance of controllers. Rectifier simulation is performed in Matlab / Simulink environment by using hysteresis current control, sinusoidal pulse width modulation and voltage oriented control techniques. In the performance comparison of the control techniques, considering the switching frequencies, the total harmonic content of the current drawn from the grid, the phase difference between the grid voltage and the grid current, and the DC bus voltage regulation at the output are considered as comparison criteria. The switching frequency is set to 35 kHz in sinusoidal pulse width modulation and voltage oriented control techniques. Since the switching frequency is variable in the hysteresis current control technique, the average and instantaneous switching frequency are calculated for different hysteresis band values. In the results with the technique, the switching frequency varies between 18.52 kHz and 47.6 kHz, while the average switching frequency is 34.6 kHz. As a result, the total harmonic distortion of the grid current with hysteresis current control, sinusoidal pulse width modulation and voltage oriented control techniques is 3.69%, 1.12% and 1.82%, respectively. The synchronization with the grid voltage is achieved with all techniques, and the DC voltage is regulated with active power. TEK FAZLI PWM DOĞRULTUCU KONTROL TEKNİKLERİNİN KARŞILAŞTIRILMASI Özet Bu çalışmada, 2.5kW gücünde tek fazlı darbe genişlik modülasyonlu doğrultucunun üç farklı kontrol yönteminde simülasyonu yapılarak bu yöntemlerin performansı incelenmiştir. Histerezis akım kontrolü, sinüzoidal darbe genişlik modülasyonu ve gerilim odaklı kontrol yöntemleri kullanılarak Matlab/Simulink ortamında doğrultucu simülasyonu gerçekleştirilmiştir. Kontrol yöntemlerinin performans karşılaştırmalarında anahtarlama frekansları dikkate alınarak şebekeden çekilen akımın toplam harmonik içeriği, şebeke gerilimi ile arasındaki faz farkı ve çıkıştaki DC bara gerilimi regülasyonu karşılaştırma kriterleri olarak ele alınmıştır. Sinüzoidal darbe genişlik modülasyonu ve gerilim odaklı kontrol yöntemlerinde anahtarlama frekansı 35 kHz seçilmiştir. Histerezis kontrol yönteminde anahtarlama frekansı değişken olduğundan dolayı farklı hata bandı değerleri için anahtarlama frekans değişimi hesaplanarak ortalama ve anlık anahtarlama frekansı tespit edilmiştir. Histerezis akım kontrol yönteminde anahtarlama frekansı 18,52 kHz ile 47,6 kHz aralığında değişirken ortalama anahtarlama frekansı 34,6 kHz olmuştur. Yapılan çalışma sonucunda histerezis akım kontrolü, sinüzoidal darbe genişlik modülasyonu ve gerilim odaklı kontrol yöntemlerinde şebeke akımı toplam harmonik bozulumu sırasıyla %3,69, %1,12 ve %1,82 olmuştur. Tüm yöntemlerde şebeke ile senkronizasyon sağlanmış ve DC bara gerilimi regülasyonu şebekeden aktif güç çekerek gerçekleştirilmiştir. Anahtar Kelimeler: Histerezis akım control, Sinüzoidal PWM, Doğrultucu Cite ISEN, E., (2021). "Comparative Study Of Single-Phase Pwm Rectifier Control Techniques", Mugla Journal of Science and Technology, 7(1), 44-52.

Conventional controllers are generally used to control the speed of the separately excited DC motors in various industrial applications. It is found to be simple and high effective if the load disturbances is small. So the drawback of Conventional controllers when high load has been applied to the DC motor. This paper presents the speed control of a separately excited dc motor using Fuzzy Neural Model Referance controller. The system has been implemented using Matlab/Simulink software. The simulation results show that presenting controller give good performance and high robustness in load disturbance.

This work presents a non-linear carrier current control technique to improve the power factor and reduce the distortion of input current in soft switched Interleaved Boost Converter (IBC). This Interleaved Power Factor Correction (IPFC) circuit is studied and investigated in MATLAB. The performance of the circuit configuration is recorded under open loop and closed loop operation. SPARTAN/FPGA is employed to execute the control technique. The vital parameters such as energy factor, voltage regulation, input power factor, input distortion factor, power losses and efficiency are computed. The hardware has been built with non-linear carrier current control strategy and the results are verified.

Non-linear load deteriorates the quality of current waveforms at the point of common coupling of various consumers. Active power filter (APFs) is used to mitigate the most concern harmonic pollution in an electrical network. The controller part is the nucleus of an active power filter configuration. Active power filter performance is affected significantly by the selection of current control techniques. The active filter and its current control must have the capability to track sudden slope variations in the current reference to compensate the distorted current drawn by the voltage source inverter. Therefore, the choice and implementation of the current regulator is more important for the achievement of a satisfactory performance level. In this survey, technical reviews of various types of controllers covering a wide range have been presented. This work also reveals the advantages and disadvantages of the practiced control strategies. The effectiveness of the study will help the researchers to choose the proper control methods for various applications of active power filter.

Link to full text journal :
https://automatika.korema.hr/index.php/automatika/article/view/572

This paper presents the utilization of a PEM fuel cell as a main power source in a distributed generation system, particularly for future electric vehicle applications. One of the main weak points of the fuel cell is its time constants dominated by temperature and fuel delivery system (pumps, valves, and in some cases, a hydrogen reformer). As a result, fast load demand will cause a high voltage drop in a short time, recognized as a fuel starvation phenomenon. Therefore, to employ a PEM fuel cell in dynamic applications, the electrical system must have at least an auxiliary power source to improve system performance when electrical loads at a dc bus demand high energy in a short time. The possibilities to use a supercapacitor or battery bank as an auxiliary source with a fuel cell main source is presented in detail. The very fast power response and high specific power of a supercapacitor or high specific energy of battery can complement the slower power output of the main source to produce the compatibility and performance characteristics needed in a load. The studies of two hybrid power systems for vehicle applications: a fuel cell/battery and a fuel celli supercapacitor hybrid power sources are explained. Experimental results in laboratory authenticate that energy storage devices can assist the fuel cell to meet the vehicle power demand and help achieve a better performance.

This paper, presents a novel idea for analog current comparison which compares input signal current and reference currents with high speed, low power and well controlled hysteresis. Proposed circuit is based on current mirror and voltage latching techniques which produces rail to rail output voltage as a result of current comparison. The same design can be extended to a simple current comparator without hysteresis (or very less hysteresis), where comparator gives high accuracy (less than 50nA) and speed at the cost of moderate power consumption. The comparators are designed optimally and studied at 180nm CMOS process technology for a supply voltage of 3V.

Nowadays, widespread use of power electronics based load in house-hold and industry have increased the importance and application of power Quality studies. Power electronic devices having property of non-linearity draw harmonic and reactive power from the source. Unified Power Quality conditioner (UPQC) is the device that mitigates the harmonics and improves the quality of power. This paper presents the working principle of UOQC based on instantaneous p-q theory which compensates the load current harmonics and reactive power at the load side. The performance of the proposed UPQC and its controller is tested through MATLAB SIMULATION.

Keywords: UPQC, shunt active filter, hysteresis current controller.

The standard grid codes suggested, that the wind generators should stay in connected and reliable active and reactive power should be provided during uncertainties. This paper presents an independent control of Grid Side Converter (GSC) for a doubly fed induction generator (DFIG). A novel GSC controller has been designed by incorporating a new Enhanced hysteresis comparator (EHC) that utilizes the hysteresis band to produce the suitable switching signal to the GSC to get enhanced controllability during grid unbalance. The EHC produces higher duty-ratio linearity and larger fundamental GSC currents with lesser harmonics. Thus achieve fast transient response for GSC. All these features are confirmed through time domain simulation on a 15 KW DFIG Wind Energy Conversion System (WECS).

This paper presents the utilization of a supercapaci-tor as an auxiliary power source in a distributed generation system, composed of a polymer electrolyte membrane fuel cell (PEMFC) as the main energy source. The main weak point of fuel cells (FCs) is slow dynamics because one must limit the FC current slope in order to prevent fuel starvation problems, to improve its performance and lifetime. The very fast power response and high specific power of a supercapacitor can complement the slower power output of the main source to produce the compatibility and performance characteristics needed in a load. The FC and supercapacitor characteristics are clearly presented. Experimental results with small-scale devices (supercapacitor bank: 292-F, 30-V, 400-A; PEMFC: 500-W, 40-A) illustrate excellent performance during a motor drive cycle.

This study proposes a robust and powerful finite control set-model predictive control (MPC) algorithm to control the load current with lower total harmonic distortion and efficient reference tracking. In this control, the cost functions are determined for all the possible switching states of the converter and a switching state is selected corresponding to the minimum cost function for actuating the converter in the next sampling time period. To justify the performance of the proposed MPC scheme, a comprehensive study with the carrier-based pulse-width modulation, hysteresis current control and proposed minimum cost function-based MPC of the three-phase load current has been verified in MATLAB Simulink as well as the validation with dSPACE RTI1104 experimentation. This study validates the robustness of the proposed minimum cost function-based MPC control with a RL-load and three-phase induction motor (IM) load. The simulation and experimental results justifies the proposed MPC algorithm with potential tracking of the RL-load current corresponding to the reference current with lower harmonic contents as well as tracking of predictive torque and flux compared to the nominal torque and reference flux of IM, respectively.

http://digital-library.theiet.org/content/journals/10.1049/iet-pel.2014.0368

We present the numerical analysis of the high order terms in the polynomial series of the Landau density energy. We compare the profiles and hysteresis of three series of Landau equations. First series is up to the only fourth order, the second and the third series are up to the sixth and eighth terms. The polarisation profile curves are obtained by minimizing the Landau equation and solved it using root finding technique while the hysteresis is obtained by solving Landau-Khalatnikov equation. It is found that those three series of Landau model possese similar polarisation profiles and also similar hysteresis when the system is set near Curie temperature, around 40K to 50 K for the Tc of 50 K. If the temperature of the system is decreased further away from the Curie temperature, we have to consider the high order terms in Landau free energy expression. Keywords— higher order, Landau theory, hysteresis I. INTRODUCTION Landau theory is well known as a suitable approximation to explain the properties of the system in the equilibrium condition near phase transition [1]. The transition between two phases which have different symmetry in their thermodynamic state is described by order parameter, a physical entity which values (non-zero or zero) depend on the symmetry of the state. It has non-zero value in the ordered state, while in disordered phase, the value is zero [2]. This phenomenological theory has been used to study the system with long range interaction, near phase transition such as ferroelectric-paraelectric [3] and ferromagnet-paramagnet [4] using electric polarization P and magnetization M as order parameters, and also phase transitions in magnetoelectric multiferroics using both polarization and magnetization. The free energy of the system is approximated by growing the order parameter in power series. This free energy then becomes the starting point to study other parameters of the system. For example, the value of the order parameter in a certain temperature can be obtained by solving the minimum condition of the free energy of the system [2]. The response of the order parameter to the applied disturbance of such fields is also calculated based on the free energy system using Landau Khalatnikov equation yielding the hysteresis curve [5,6]. In the series of order parameter expressing the free energy, we can also add other terms such as the surface effect, the depolarization term, etc. to complete the behaviour of the system [7].

En este artículo se analiza el comportamiento local y global de un sistema dinámico suave a trozos en dos variables, estudiando el flujo de dos sistemas dinámicos lineales no homogéneos que conmutan con las fronteras de una banda de histéresis. Analíticamente se determinan las soluciones de equilibrio y los dominios paramétricos que garantizan la existencia de órbitas periódicas entre la banda. Se realizan simulaciones numéricas para obtener los retratos de fases y los dominios de atracción con diferentes valores de los parámetros. Los resultados muestran la coexistencia de múltiples estados estacionarios de diferente tipo para determinados valores de los parámetros. Palabras clave: Histéresis; órbita periódica; sistemas dinámicos suaves a trozos; dominios de atracción.

The integration of distributed generation like solar and wind are increasing nowadays due to fossil fuel reduction and increased carbon emission. Many integration issues arise of connecting Solar PV to the grid out of which power quality is the important factor. Higher PV injection causes undesirable technical impacts on the distribution networks which leads to power quality issues. This paper studies the impact of PV on the power quality of the utility grid with different levels of penetration of solar energy into the grid. The power quality of the grid is studied using the Total harmonic distortion (THD) by performing Fast Fourier Transform (FFT) analysis. This paper deals with the development of controllers for boost converter and grid tied inverters which minimizes the harmonics due to solar PV system and power converters in grid connected PV system. The Maximum Power Point Tracking (MPPT) for boost converter and Hysteresis current control (HCC) for inverter has been designed and implemented in grid connected PV system. The hysteresis current controller for the inverter has been specifically designed to reduce the THD of the system meeting IEEE519_1992 regulations. The simulation model of the grid connected PV system has been designed in MATLAB 2018b version. The comparison studies are carried out in the PV system with and without hysteresis current controller, after which it can be concluded that, after the incorporation of the hysteresis current controller, the performance of the system is better in terms of power quality.

The standard grid codes suggested, that the wind generators should stay in connected and reliable active and reactive power should be provided during uncertainties. This paper presents an independent control of Grid Side Converter (GSC) for a doubly fed induction generator (DFIG). A novel GSC controller has been designed by incorporating a new Enhanced hysteresis comparator (EHC) that utilizes the hysteresis band to produce the suitable switching signal to the GSC to get enhanced controllability during grid unbalance. The EHC produces higher duty-ratio linearity and larger fundamental GSC currents with lesser harmonics. Thus achieve fast transient response for GSC. All these features are confirmed through time domain simulation on a 15 KW DFIG Wind Energy Conversion System (WECS).

Porous material in contact with vapor tends to adsorb fluid in the pores. The amount of adsorbed fluid depends on the vapor pressure, but depends in some parameter ranges as well on the history of the system. When raising the vapor pressure the adsorption may be smaller than while lowering the pressure. Thus, the measured adsorption isotherm consists of two branches that appear stable on the time scale of experiments. The phenomenon is known as adsorption hysteresis and has been extensively discussed in the literature as it is in distinct contrast to the expectations of thermodynamics:the system has more than one answer to one set of boundary conditions (here: grand canonical boundary conditions). The common explanation offered in the literature introduces the concept of metastable states, conceiving either or both branches of the isothermas being metastable. Even though the concept of metastability cannot be separated from the concept of a lifetime against decay into the corresponding ground state, this aspect is usually not discussed in the literature. Within the adsorption community it is agreed upon that the concept of metastable states brings the experimental findings in harmony with the theory of thermodynamics while the lifetime of the conceived metastable states is disregarded. In the present paper we challenge this notion. We argue that the characteristic lifetime sys τ of a system against decay into its ground state must be compared with the duration exp τ of the experimental technique employed to investigate the behavior of the system. Based on experimental evidence and based on previous theoretical results we find that the relation exp τ τ >> sys holds for typical adsorption systems. As thermodynamics is founded on the assumption exp τ τ << sys it cannot be the appropriate theory for describing adsorption systems.Several schemes found in the literature seem to provide such a time dependent approach. Our analysis, however, shows that neither of these attempts describes the time dependence in a realistic way. Thus, we have to conclude that no valid theory for the propagation of adsorption systems in time has emerged yet. We propose to develop a new generally valid time dependent theory for confined systems whose time independent limit for 0 exp → sys τ τ would be suited to handle adsorption systems. Keywords: adsorption hysteresis ⋅ lifetime of metastable states ⋅ time dependent theory