This paper describes the transient characteristics and control of the output DC voltage of a stand-alone switched reluctance generator (SRG). A mathematical model of switched reluctance machine (SRM) is developed and implemented in Matlab/Simulink software. The mathematical model is verified experimentally. The robust controller based on the discrete-time sliding mode control (DT-SMC) technique is proposed for the SRG voltage control. The robustness is achieved using the disturbance estimator. The proposed control technique was implemented through simulations on a three phase 12/8-pole SRG with a variable speed and load. The proposed DT-SMC based controller is compared with a standard PI controller. Obtained results show the effectiveness and quality of DT-SMC based voltage control technique for the SRG.

This paper presents a new dead-beat control design for a class of multi-input linear time-invariant continuous-time controllable systems. The system is controlled using multi-rate sampled data. First step in design is to obtain the controllability index vector. Using elements of this vector known as controllability indices, the state feedback matrix is computed applying higher order sliding mode control approach. The number of sliding variables is equal to the number of control inputs. Obtained control annihilates system state in a minimal number of sampling periods which is equal to the maximal value of controllability indices. Since, the dead-beat control has poor robustness, a disturbance compensation is designed. In this paper, the compensation control is equal to the negative value of the disturbance estimate. The estimate is obtained using the equivalent control approach, while the compensation sampling period is not the same as the deadbeat control sampling period. The control is formed as the dead-beat control term and the compensation control which suppressed disturbance effects. The sampling period of compensation control is generally smaller than the control sampling period. Properties of the proposed control system are demonstrated on a simulation example.

This paper describes the transient performance and voltage regulation of a stand-alone self-excited induction generator (SEIG). All characteristics are calculated with a ftux-based mathematical model of the induction machine in the stationary reference frame appropriate for the stand-alone SEIG. The generator model and the control system model are developed using Matlab/Simulink. A presented generator model takes into account significant effects of magnetic saturation on the SEIG performance. The simulation was performed by loading the SEIG with a variable resistive load. Some of the computed characteristics are compared with experimental results. Both uncontrolled and controlled response of the SEIG to load variations were analyzed. It is shown that voltage variations can be reduced by using voltage source inverter and terminal voltage controller.

This paper introduces a control method for finite time stabilization of continuous-time controllable linear time invariant multiple-input multiple-output systems. The proposed approach uses higher order sliding mode control to reduce the system order to zero and thus providing the system states to reach the origin in finite time. Such control is called finite time order zeroing control, because it annihilates all sliding variables and their associated derivatives in finite time, while system states converge to equilibrium point. Sliding manifold reaching control uses quasi-continuous control functions. Properties of the proposed control system are demonstrated on a simulation example of a real system model.

The digital speed control systems of a DC motor are treated in this paper. The parameters of DC motor were not known, so that the parameter estimation and model identification is carried out first. Two control systems are considered: a classical discrete PI controller and a discrete-time sliding mode controller. Problems of robustness to matched parameter uncertainties and outer disturbances were addressed by comparing PI controller outputs with DT-SMC controller with disturbance compensator. These control systems were compared in MATALB/Simulink, and on the laboratory setup using three characteristic scenarios. At the end, experimental results are compared with the results obtained by simulation.

This paper proposes a finite time control for a class of linear time invariant multi-input continuous-time (CT) and discrete-time (DT) controllable systems. The main idea is to reduce the system order to zero, by using higher sliding control which drives states to origin in finite time. The control scheme is fully decentralized and differentiators are not needed for control realization. The CT reaching control uses the quasi-continuous control. For DT systems a new type of order reducing control named multi-step equivalent control is proposed. This control annihilates both the switching functions and states in a finite number of discrete time units, resulting in a dead-beat control.

A new design of a digital control system for the grid-connected doubly fed induction generator is described in this paper. A discrete-time state-space model of the controlled system is obtained in the stator stationary reference frame. Using this model, a discrete-time sliding mode based control system is designed. Its tasks are the grid synchronization and the direct power control. The discrete-time equivalent control method is applied, and the control vector is calculated from the samples of voltages and currents. The control vector is converted to a switching sequence in a power converter using the space vector modulation. The modulation period is equal to the sampling period. A disturbance compensator is designed to eliminate the influence of the discretization effect and model uncertainties. In this way, a robust control system with a constant switching frequency is designed. Its digital hardware implementation is simple. The performance of the designed control system is tested on a simulation model.

This paper presents a design of a direct power control using the discrete-time sliding mode control. The design is intended for a grid-connected inverter or a doubly fed induction generator. The constant switching frequency is implemented by the space vector modulation, having the modulation period equal to the sample period. The effects of the discretization and external disturbances are analyzed. To solve this problem, a power based disturbance compensator is proposed. Its digital hardware implementation is simple. The simulation results show that the designed control system has a better steady state performance and robustness than a non-compensated control system.

This paper presents a design of a digital direct power control strategy for a three-phase grid-connected inverter combining the discrete-time sliding mode control and the space vector modulation. Using the discrete-time state-space model of the controlled system, a discrete-time sliding mode control system is designed. Its output is a control vector which minimizes the instantaneous active and reactive power displacement from their reference values. The control vector is computed from the samples of voltages and currents and then converted to a switching sequence using space vector modulation. The period of modulated signal is equal to the sample period. A correction of the control vector is defined with aim to eliminate the influence of the system uncertainties using predicted values of the active and reactive powers. In this way a robust control system with a constant switching frequency is designed. Its digital hardware implementation is very simple. This control system is tested on a simulation model and compared with other similar approaches.

This paper presents a novel Direct Power Control strategy for a three-phase grid connected multilevel inverter. The proposed DPC strategy combines discrete-time sliding mode control and predictive control. The active and reactive power are directly controlled by inverter switching states, represented by a switching vector, using the value of the power error computed from samples of phase voltages and currents. An appropriate switching vector is selected for each sampling period to minimize average value of the switching functions on the time interval on three sampling periods. The prediction of phase voltages and currents is necessary for algorithm implementation. The switching frequency is constant, and the digital control implementation is simple. The designed control system is tested using a simulation model of a three-level neutral-point clamped multilevel inverter. Simulation results confirm the design aims.

This paper presents an approach to Direct Power Control (DPC) of a three-phase grid connected three level neutral-point clamped inverter. The presented approach can be extended to other topologies of multilevel inverters. The proposed DPC strategy is based on the Sliding Mode Control (SMC). The active and reactive power are directly controlled by three-level inverter switching states using the value of the delivered power error calculated from previous samples of three phase voltages and currents. An optimal control vector defined in dq reference frame minimizing the ripple is obtained using predicted values of three phase currents. An appropriate switching sequence is generated for each optimal vector using direct and indirect way. In the direct way the switching vector the nearest to the optimal control vector, and the direct way uses space vector modulation. The proposed strategy is robust to system parameters variations. The major advantage of proposed approach is its simple analog/digital control implementation. Moreover, PID controllers, look-up tables, and pulse-width modulators are not necessary. The designed control system is tested on a simulation model of a three-level neutral-point clamped multilevel inverter. Simulation results of a three-level neutral-point clamped multilevel inverter topology confirm the design aims.

This paper presents a new approach to Direct Power Control (DPC) strategy using Space Vector Modulation (SVM) for the three-phase grid connected Voltage Source Converter (VSC) in the Renewable Energy Sources (RESs). The proposed DPC strategy is based on the Sliding Mode Control (SMC) and it is implemented in the dq reference frame. The active and reactive powers are directly controlled by VSC switching states selection based on the instantaneous value of the delivered power error. This strategy may be implemented to various VSC topologies. Moreover, linear controllers and modulators are not necessary. The aim of the control strategy is to inject maximal available active power and a controlled amount of reactive power into grid. The strategy is tested on a simulation model of a multilevel VSC (ML-VSC). Simulation results of the tested VSC topology and harmonic analysis of the output signals are presented at the end.

The paper presents a new approach to control of the reactive power supply from renewable energy sources to the grid. The aims of control algorithm are: maximal power extraction from the wind or solar power and its injection into the power grid and the control of reactive power supplied to the grid. The value of reactive power is controlled by magnitude of internal voltage E and phase angle δ between internal E and external V voltages vectors. The needed magnitude E and phase angle δ are calculated from the measured values of the supplied active power Pg and the desired supply of the reactive power Qg_ref. These expressions are obtained by comparing mathematical models of the power converter and the synchronous generator. This concept was implemented on the abc stationary reference frame and its effectiveness was demonstrated on a simulation model of the power converter connected to an infinite bus.