Yazan M. Alsmadi

Sliding mode control of three-phase, boost-type and three-Wire, single-phase AC/DC power converters

This paper presents a novel control strategy of three-phase, boost-type and, three-Wire, single-phase AC/DC Power Converters AC/DC power converters. The proposed control algorithm is based on Sliding Mode Control methodology. The basic idea is to apply a feedback implementation of pulse-width modulation (PWM). The method exhibits low sensitivity to disturbances and fast dynamic performance in addition to the main converter properties. The proposed sliding mode control method ensures that the power converter has the following properties: pure sinusoidal input currents at unity power factor from the AC line and low level of DC output voltage ripple. Discussion starts with the circuit model and design methodology of three-phase, boost-type and single-phase, three-wire AC/DC Power Converters. Then, a sliding mode current control tracking system is designed for both converters. Finally, output voltage control is developed. The effectiveness of the proposed control strategy has been demonstrated through various simulation cases.

Analytical model for the minimization of torque ripple in permanent magnets assisted synchronous reluctance motors through asymmetric rotor poles

Synchronous Reluctance motor has recently gained popularity in applications where induction motors are normally employed. Additionally, when permanent magnets are buried in the rotor, they become an alternative for high performance applications. Some of its drawbacks such as high torque ripple and low power factor need to be overcome. The design of Synchronous Reluctance motors with asymmetric flux barriers has been recently used to reduce torque ripple. Finite element models are necessary tool to find the right place and dimensions of the flux barriers as well as to predict the torque harmonics. However, it is time consuming to analyze the model since periodicity and symmetry conditions cannot be used to reduce the model to a single pole. Therefore, in this paper an analytical model is presented to rapidly and accurately study the effect of such asymmetry of rotor poles on the torque ripple. The proposed approach is developed for symmetrical and asymmetrical geometries and validated against finite element models.

Sliding mode control of power converters: DC/DC converters

ABSTRACT In recent years, a lot of research efforts have been devoted to the application of sliding mode control (SMC) techniques to power electronic equipment and electrical drives. Hundreds of technical papers have been published in this research field. The tendency stems from the nature of sliding mode with discontinuous control actions and due to its potential for circumventing parameter variation effects along with low implementation complexity. This paper presents a control design procedure for DC/DC power converters. It develops SMC algorithms for several types of DC/DC converters with different control objectives, complete and incomplete information about system states. A chattering reduction approach for power converters based on the idea of multi-phase converters is also proposed. A wide range of MATLAB/SIMULINK computer simulations along with experimental results are provided to demonstrate the effectiveness of the proposed control design.

High-Fidelity Nonlinear IPM Modeling Based on Measured Stator Winding Flux Linkage

This paper focuses on a novel modeling method for Interior Permanent Magnet (IPM) synchronous machines. This modeling method is based on a flux table which is obtained from experimental testing. As indicated by the comparison between computer simulation and dyno testing, this modeling approach can model the nonlinear behavior of Interior Permanent Magnet synchronous machines with high fidelity without adding significant computational loads.

FEA-based performance calculations of IPM machines with five topologies for hybrid-electric vehicle traction

This paper presents a detailed calculation of the characteristics of five different topologies of permanent magnet (PM) machines for high performance traction including hybrid electric vehicles using the Finite Element Analysis (FEA) method. These machines include V-shape single layer interior PM, W-shape single-layer interior PM, Segment interior PM and Surface PM on the rotor with distributed winding on the stator. The performance characteristics include the back-EMF voltage and its harmonics, magnet mass, iron loss and ripple torque. In addition, a 7.5 kW IPM prototype was tested in order to verify the finite-element analysis results. The aim of this paper is to provide a reference for machine designers who are interested in IPM machine selection for high performance traction applications.

Sliding Mode Control of Underground Coal Gasification Energy Conversion Process

The control of highly complex and nonlinear underground coal gasification (UCG) energy conversion process is a challenging job. As the process occurs under the surface of the earth, so it is either impossible or very expensive to measure all the important parameters, which further complicates the control design. The input of the UCG process is the flow rate of the injected air and the heating value of the product gas is the output. In this paper, a sliding mode control (SMC) algorithm is designed for a simplified model of an actual UCG process in order to maintain a desired constant heating value. The relative degree of the sliding variable is zero, because the input is readily available in it. As the heating value is the only measurement available, the trivial control design is not possible. Therefore, the time derivative of the control is selected as the system input, and then the relative degree becomes one and the conventional SMC may be implemented. This approach let us maintain the output at the desired level and provides insensitivity with respect to different types of uncertainties. The stability of the zero dynamics is proved, which ensures that the overall system is stable. The simulation results demonstrate the robustness of the SMC design against the input disturbance and the modeling inaccuracies.

Comprehensive analysis of the dynamic behavior of grid-connected DFIG-based wind turbines under LVRT conditions

Power generation and grid stability have become key issues in the last decade. The high penetration of large capacity wind generation into the electric power grid has led to serious concerns about their influence on the dynamic behavior of power systems. The Low-Voltage Ride-Through (LVRT) capability of wind turbines during grid faults is one of the core requirements to ensure stability in the power grid during transients. The doubly-fed induction generators (DFIGs) offer several advantages when utilized in wind turbines, but discussions about their LVRT capabilities are limited. This paper presents a comprehensive study of the LVRT of grid-connected DFIG-based wind turbines. It provides a detailed investigation of the transient characteristics and the dynamic behavior of DFIGs during symmetrical and asymmetrical grid voltage sags. A detailed theoretical study supported by computer simulations is provided.

Sliding Mode Control Design Procedure for Power Electronic Converters Used in Energy Conversion Systems

Due to its order reduction property, good dynamic performance and low sensitivity to disturbances and plant parameter variations, sliding mode control (SMC) has been the method of choice for handling nonlinear systems with uncertain dynamics and disturbances.

Robust multi-objective control design for underground coal gasification energy conversion process

ABSTRACT The efficiency of an underground coal gasification (UCG) energy conversion process can be increased by maintaining a desired heating value of the product gases. In literature this task has been accomplished by adopting nonlinear model-based control strategies. To exploit the flexibility of the linear control design techniques, a linear model of the UCG process has been developed, which retains the dynamics of the nonlinear model around the operating point of interest. To account for external disturbance and modelling inaccuracies, an output-based robust multi-objective H2/H∞ control law integrated with pole placement has been proposed. The problem is solved by formulating linear matrix inequality (LMI) constraints for performance and robustness. The simulation results show that the designed controller gives adequate performance in the presence of modelling inaccuracies and external disturbance. Moreover, it has been shown that performance of the designed controller is better as compared to the standard PI controller.

Sliding-mode control of power converters: AC/DC converters & DC/AC inverters

ABSTRACT Sliding-Mode Control (SMC) has been widely utilised to control nonlinear systems with uncertain dynamics. This is due to its order reduction properties, low sensitivity to disturbances, great dynamic performance and ability to reduce the complexity of feedback control design by decoupling the system into independent lower dimensional subsystems. Therefore, significant research has been dedicated to the application of SMC techniques to power electronic equipment and electrical drives. This paper presents a comprehensive control design procedure for AC/DC converters and DC/AC inverters based on SMC. It develops SMC algorithms for several types of power electronic equipment with different control objectives, complete and incomplete information about system states. A wide range of MATLAB/SIMULINK computer simulations are provided to demonstrate the effectiveness of the proposed control design.