DC-AC Inverter System Research Articles

Continuous dynamic sliding mode control strategy of PWM based voltage source inverter under load variations

For closed-loop controlled DC-AC inverter system, the performance is highly influenced by load variations and online current measurement. Any variation in the load will introduce unwanted periodic error at the inverter output voltage. In addition, when the current sensor is in faulty condition, the current measurement will be imprecise and the designed feedback control law will be ineffective. In this paper, a sensorless continuous sliding mode control (SMC) scheme has been proposed to address these issues. The chattering effect due to the discontinuous switching nature of SMC has been attenuated by designing a novel boundary-based saturation function where the selection of the thickness of boundary is dependent to the PWM signal generation of the inverter. In order to remove the dependency on the current sensor, a particle swarm optimization(PSO) based modified observer is proposed to estimate the inductor current in which the observer gains are optimized using PSO by reducing the estimation errors cost function. The proposed dynamic smooth SMC algorithm has been simulated in MATLAB Simulink environment for 0.2-kVA DC-AC inverter and the results exhibit rapid dynamic response with a steady-state error of 0.4V peak-to-peak voltage under linear and nonlinear load perturbations. The total harmonic distortion (THD) is also reduced to 0.20% and 1.14% for linear and non-linear loads, respectively.

Robust Voltage Regulation of a DC–AC Inverter With Load Variations via a HDOBC Approach

In this brief, a harmonic disturbance observer (HDOB) based control approach is proposed for the robust voltage regulation design of a dc-ac inverter system. In distributed generation systems, wide range of load variations and effects of nonlinear loads result in significant degradations of control performance. Moreover, the loads, as the mismatched disturbances, impose adverse influences on the inverter system via a channel different from the control input. Toward that end, an HDOB is proposed to estimate the periodic load disturbances. By constructing new disturbance compensation gains, the effects of the mismatched periodic disturbances are removed from the output voltage channel. Rigorous stability analysis for the closed-loop system is presented. Experimental results are explored to illustrate the feasibility and capacity of the proposed control scheme.

Maximum Power Point Tracking in Grid Connected Wind Plant by Using Intelligent Controller and Switched Reluctance Generator

This paper presents intelligent controllers as a maximum power point tracking system for a switched reluctance generator (SRG) driven by a variable speed wind turbine to attain the maximum power. The intelligent controller systems are artificial neural network (ANN) controller and fuzzy logic (FL) controller. Both controllers manipulate the wind turbine rotational speed by changing turn-off angle of the SRG. The turn on angle is fixed. The wind plant is connected to the grid through a DC–AC inverter system and two step up power transformers. The systems are simulated in MATLAB/ Simulink environment. The results show that the ANN controller is more accurate and efficient than the FL controller.

Universal active disturbance rejection control for non‐linear systems with multiple disturbances via a high‐order sliding mode observer

This study is concerned with the output feedback control design for a class of non-linear systems subject to multiple sources of disturbances/uncertainties including parameter perturbations, complicated non-linear dynamics and external disturbances. By developing the high-order sliding mode observer, both state and disturbance observations are incorporated into the controller design. By means of the lumped disturbance estimation as well as virtual state estimations, a composite output feedback controller combined with an additional feedforward compensation is proposed. The stability of the closed-loop system is rigorously demonstrated based on Lyapunov stability criterion. Application of the proposed approach to a single-phase DC-AC inverter system is finally implemented with experimental results to validate the feasibility and effectiveness.

Speed control of grid-connected switched reluctance generator driven by variable speed wind turbine using adaptive neural network controller

In wind energy conversion system, variable speed operation is becoming popular nowadays, where conventional synchronous generators, permanent magnet synchronous generators, and doubly fed induction generators are commercially used as wind generators. Along with the existing and classical solutions of the aforementioned machines used in wind power applications, the switched reluctance generator (SRG) can also be considered as a wind generator due to its inherent characteristics such as simple construction, robustness, low manufacturing cost, etc. This paper presents a novel speed control of switched reluctance generator by using adaptive neural network (ANN) controller. The SRG is driven by variable speed wind turbine and it is connected to the grid through an asymmetric half bridge converter, DC-link, and DC–AC inverter system. Speed control is very important for variable speed operation of SRG to ensure maximum power delivery to the grid for any particular wind speed. Detailed modeling and control strategies of SRG as well as other individual components including wind turbine, converter, and inverter systems are presented. The effectiveness of the proposed system is verified with simulation results using the real wind speed data measured at Hokkaido Island, Japan. The dynamic simulation study is carried out using PSCAD/EMTDC.

Filter design method for a PWM feedback inverter system

A novel approach to filter design for a closed-loop, pulse-width-modulated (PWM) DC-AC inverter system driving an RL load is investigated. The system has a rectangular hysteresis in the forward path and it is closed by current feedback. When it is excited by a sinusoidal input reference, it provides square pulses that produce a nearly sinusoidal current in the load. Using a describing function technique, design equations for the filter are derived. The data needed for the filter evaluation are the amplitude of current ripple and the frequency of square pulses delivered by the power bridge. System simulation and experimental results show that the design of the filter can be based on the method proposed and that the filter can provide a significant reduction of current ripple, or otherwise a significant reduction of switching frequency.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>