Hysteresis Band Current Controller Research Articles

Sliding-Mode Control for a Three-Phase Unity Power Factor Rectifier Operating at Fixed Switching Frequency

This paper presents an improved variable hysteresis-band current-control in natural frame for a three-phase unity power rectifier. The proposed control algorithm is based on three decoupled sliding-mode controllers combined with three independent Kalman filters. The use of Kalman filters instead of a nonadaptive state observer improves the quality of the estimated signals in presence of noise, increasing the immunity of the control loop in noisy environments. To reduce drastically the computational load in the Kalman algorithm, a reduced bilinear model is derived which allows to use a Kalman filter algorithm instead of an extended Kalman filter. A fast output-voltage control is also presented which avoids output-voltage variations when a sudden change in the load or a voltage sag appears. Moreover, a fixed switching frequency algorithm is proposed which uses a variable hysteresis-band in combination with a switching decision algorithm, ensuring a switching spectrum concentrated around the desired switching frequency. The overall control proposal has been fully integrated into a digital signal processor. Selected experimental results are introduced to validate the theoretical contributions of this paper.

A New Approach for Constant DC Link Voltage in a Direct Drive Variable Speed Wind Energy Conversion System

Due to the high efficiency and compact mechanical structure, direct drive variable speed generators are used for power conversion in wind turbines. The wind energy conversion system (WECS) considered in this paper consists of a permanent magnet synchronous generator (PMSG), uncontrolled rectifier, dc-dc boost converter controlled with maximum power point tracking (MPPT) and adaptive hysteresis controlled voltage source inverter (VSI). For high utilization of the converter's power capability and stabilizing voltage and power flow, constant DC-link voltage is essential. Step and search MPPT algorithm which senses the rectified voltage (<TEX>$V_{DC}$</TEX>) alone and controls the same is used to effectively maximize the output power. The adaptive hysteresis band current control is characterized by fast dynamic response and constant switching frequency. With MPPT and adaptive hysteresis band current control in VSI, the DC link voltage is maintained constant under variable wind speeds and transient grid currents respectively.

A new hysteresis band current control technique for a shunt active filter

This paper proposes a hysteresis band (HB) current control technique to reduce the power losses in a shunt active filter. During a switching period in the zero-crossing region, the inverter output current flows through a transistor. By changing the direction, it flows through the free-wheeling diode of the same switch in an inverter leg, or vice versa. The shunt active filter current typically has 6 zero-crossing regions during a fundamental frequency cycle. This paper presents a HB current control technique where there is not any switching in these 6 zero-crossing regions per period, which results in reducing the power losses. The experimental results clearly show that the power losses of the shunt active filter are reduced by using the proposed technique.

Improvement of power quality using photovoltaic fed shunt power quality conditioner

A photovoltaic fed shunt power quality conditioner for harmonic and reactive power compensation is presented in this paper. A new control algorithm based on load active power consumption is implemented to improve the performance of the current controller under non-sinusoidal mains voltage condition. The presence of solar system decreases the voltage stress on the conventional supply system and also compensates a part of load active power during the availability of sunlight. A fixed band hysteresis current controller is used to generate switching pulses of insulated-gate bipolar transistor inverter. The concept is realised by time domain computer simulation of the model under different mains voltage, symmetrical and unsymmetrical fault on load and dynamic load condition. The viability and effectiveness of the designed PVSAF and its competence in meeting the IEEE-519 recommended harmonic standard limits is also verified through experimentation.

English

The tradition of non-linear loads in Electrical power system has sparked the research in power quality (PQ) concern like voltage flicker, voltage sag and swell, harmonics, etc., Among all the other concerns, one of the major significant PQ problem is Harmonics. The inception of Nonlinear Load into the power system will have the effect of harmonics. These nonlinear loads appear to be prime sources of harmonic distortion in a power distribution system. Harmonics have a number of undesirable effects like Voltage flicker, voltage sag and swell, harmonics etc., on the distribution system. These harmonics are to be mitigated for Power Quality Enhancement. The STATCOM is one of the FACTS Devices which can be used to mitigate the harmonics. The necessity of using intelligent tools in power quality analysis is increasing day by day to enhance power quality in the utility. This paper deals with analysis and comparison of optimized PI based Differential Evolution (DE) technique and controlled fuzzy-PI controller with conventional PI controller used in STATCOM for harmonic reduction in the source current. SRF theory is used to generate the reference compensating currents. Hysteresis Band Current Controller (HBCC) is used to control the switching of Voltage Source Inverter.

English

4 ABSTRACT: Power quality of the system will be affected due to the increasing use of power electronic equipment and nonlinear loads. Active power filters (APFs) are effective in mitigating line current harmonics and can improve the power quality. In this paper, instantaneous active and reactive power (p-q) theory is employed to generate the reference currents and PI controller is used control the dc link voltage. The application of artificial intelligence is growing fast in the area of power sectors. The artificial neural network (ANN) is considered as a new tool to design control circuitry for power-quality (PQ) devices. The main objective of this paper is the analysis and comparision of THD of the source current with different types of controllers. Here THD of source current with conventional PI controller is compared with the artificial neural network (ANN) based PI and Particle Swarm Optimization (PSO) based PI. Hysteresis Band Current Controller (HBCC) is used to generate the gate pulses of the VSI of the filter Simulations are carried out in MATLAB/SIMULINK environment using sim power system toolbox.

Adaptive Hysteresis Current Controlled Multilevel Inverter for Solar Photovoltaic Applications

This paper presents a five-level cascaded multilevel inverter controlled by an adaptive hysteresis band current controller for photovoltaic system. Due to increasing the number of levels, the proposed five-level cascaded multilevel inverter further reduces its total harmonic distortion (THD). The solar system is simulated using MATLAB/Simscape software and it is integrated with DC–DC boost converter and single-phase five-level cascaded multilevel inverter controlled by the proposed control strategy. The simulation results show that the proposed controller provides constant switching frequency, reduced harmonics and can reach its steady state quickly compared to the conventional fixed hysteresis controller and standard PWM controller. Also, the proposed five-level cascaded multilevel inverter reduces THD of the output voltage and current. The proposed controller is also implemented Xilinx Spartan 3E field programmable gate array using the Atmel AT90USB2 USB controller on the Basys2 development board. The simulation and experimental results describe and verify the current control technique for the multilevel inverter.

Voltage stability enhancement using an adaptive hysteresis controlled variable speed wind turbine driven EESG with MPPT

This paper investigates the enhancement in voltage stability achieved while connecting a variable speed wind turbine (VSWT) driven electrically excited synchronous generator (EESG) into power systems. The wind energy conversion system (WECS) uses an AC-DC-AC converter system with an uncontrolled rectifier, maximum power point tracking (MPPT) controlled dc-dc boost converter and adaptive hysteresis controlled voltage source converter (VSC). The MPPT controller senses the rectified voltage (VDC) and traces the maximum power point to effectively maximize the output power. With MPPT and adaptive hysteresis band current control in VSC, the DC link voltage is maintained constant under variable wind speeds and transient grid currents.The effectiveness of the proposed WECS in enhancing voltage stability is analysed on a standard IEEE 5 bus system, which includes examining the voltage magnitude, voltage collapse and reactive power injected by the systems. Simulation results show that the proposed WECS has the potential to improve the long-term voltage stability of the grid by injecting reactive power. The performance of this scheme is compared with a fixed speed squirrel cage induction generator (SCIG), a variable speed doubly-fed induction generator (DFIG) and a variable speed permanent magnet synchronous generator (PMSG).

Improved brushless DC motor speed controller with digital signal processor

Brushless motors are used in many applications owing to their advantages. In most of the applications, conventional control methods with a hysteresis band (HB) controller are used. An improved speed and current control scheme for brushless DC motors with a trapezoidal shape back EMF is presented. Instead of the conventional HB and proportional-integral (PI) controllers, a fuzzy logic controller that is independent of motor equations and based on expert knowledge has been employed for current and also for speed regulation; thereby, the disadvantages of the HB are eliminated and the overall performance of the controller is enhanced. Experimental studies have been carried out with a TMS320F2812 digital signal processor. The presented control scheme has been validated through comparative experiments with the fuzzy logic speed and HB current controller. The results show that the proposed control scheme operates satisfactorily and provides a constant switching frequency.

Hysteresis Band Current Control For Harmonic Compensation of Unbalanced &amp; Nonlinear load

Hysteresis Band Current Control For Harmonic Compensation of Unbalanced &amp; Nonlinear load

Improving Switching Frequency Variation of Hysteresis Current Controlled VSI Fed Induction Motor Drive

Switching frequency variation over the entire operating speed range of an induction motor (IM) drive is the major problem associated with conventional two-level threephase hysteresis controller as well as the space phasor based pulse width modulation (PWM) hysteresis controller. This paper presents a new variable band hysteresis current controller for controlling the switching frequency variation in the two-level PWM inverter fed IM drives for various operating speeds. A novel concept of online variation of the band based on both the instantaneous load current and current change for eachsampling period is presented to determine the hysteresis band. A performance comparison of the proposed with conventional hysteresis current controller for IMdrive is provided in simulation. The proposed drive system is also implemented in real-time using DSP board DS1104 for a laboratory 1.5 hp motor. Comparative simulation andreal-time results verify the feasibility of the proposed scheme and demonstrate that the proposed method has obtained constant switching frequency and improved the performance of the drive system.

Harmonic power compensation capacity of shunt active power filter and its relationship with design parameters

In this study, the equation for the reactive and harmonic power compensation of a shunt active power filter (APF) system has been derived by studying the power exchange mechanism and power tetrahedron phasor diagram. The switching dynamics of a voltage source inverter (VSI)-based three-phase, three-wire (three-leg /half-bridge) shunt APF system with hysteresis band current control has been studied and verified by simulation. The relation between the design parameters and their effects on the active losses has also been identified. Detailed calculation and extensive simulation have been performed for a three-phase, three-wire shunt APF implemented in a 400VL-L distribution system, as an example, to study the effects of design parameter selection and their role in active power loss calculation. Simulated and calculated results are presented for the important design parameters for different switching frequencies together with their associated losses and kVA ratings. The procedure can be followed to design the parameters for other topologies, such as three-phase, four-wire or single-phase systems.

An Adaptive Hysteresis Band Current Controller Based DSTATCOM for Enhancement of Power Quality with Various Load

The Distribution Static Compensator (DSTATCOM) is used for development of power quality in power distribution network with various loads such as linear, nonlinear and variable load. The dc link capacitor voltage is directly affected by any alteration made in the load. Proper operation of DSTATCOM requires maintenance of capacitor voltage within the limits. Right from the beginning, conventional controller has been used to maintain the converter dc-link capacitor voltage. In spite of it, the transient response of the PI and Hysteresis controller is still slow. In this paper, an adaptive hysteresis band current controller is proposed for DSTATCOM to eliminate harmonics and compensate the reactive power of three-phase converter. The adaptive hysteresis band current controller is varied from the hysteresis bandwidth with respect to modulation frequency, source voltage, dc link voltage and slope of the reference compensator current wave. Mathematical expressions are given to design the adaptive hysteresis band current controller to achieve the fast transient response. The results of simulation study of the proposed method have been carried out using MATLAB simulation software.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.

Comparative Study of Hysteresis and Adaptive Hysteresis Band Current Controller under Various Loading Conditions Using PI and FLC.