http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

This book, written by two major figures in adaptive control, provides a wealth of material for researchers, practitioners, and students. While some researchers in adaptive control may note the absence of a particular topic, the book‘s scope represents a high-gain instrument. It can be used by designers of control systems to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs. The book is strongly recommended to anyone interested in adaptive control.

Adaptive Control

Multiphase variable-speed drives and generation systems (systems with more than three phases) have become one of the mainstream research areas during the last decade. The main driving forces are the specific applications, predominantly related to the green agenda, such as electric and hybrid electric vehicles (EVs), locomotive traction, ship propulsion, “more-electric” aircraft, remote offshore wind farms for electric energy generation, and general high-power industrial applications. As a result, produced body of significant work is substantial, making it impossible to review all the major developments in a single paper. This paper therefore surveys the recent progress in two specific areas associated with multiphase systems, namely power electronic supply control and innovative ways of using the additional degrees of freedom in multiphase machines for various nontraditional purposes.

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Advances in Converter Control and Innovative Exploitation of Additional Degrees of Freedom for Multiphase Machines

Multilevel inverter supplied multiphase variable-speed drive systems have in recent times started attracting more attention, due to various advantages that they offer when compared to the standard three-phase two-level drives. For proper functioning of such systems good pulsewidth modulation (PWM) strategy is of crucial importance. Control complexity of multiphase multilevel inverters increases rapidly with an increase in the number of phases and the number of levels. This paper deals with a three-level neutral point clamped (NPC) inverter supplied five-phase induction motor drive and analyses five PWM strategies: three are carrier-based (CBPWM) and two are space vector based (SVPWM). The aim is to provide a detailed comparison and thus conclude on pros and cons of each solution, providing a guideline for the selection of the most appropriate PWM technique. Experimental results are provided for all analysed PWM methods. The comparison of the PWM techniques is given in terms of the voltage and current waveforms and spectra, as well as the total harmonic distortion (THD) in a whole linear modulation index range, which is used as the global figure of merit. Properties of the common mode voltage (CMV) are also investigated. Complexity of the algorithms, in terms of the computational time requirements and memory consumption, is addressed as well. It is shown that the performance of the PWM techniques is very similar and that one CBPWM and one SVPWM technique are characterised with identical performance. However, using the algorithm complexity as the main criterion, space vector techniques are more involved.

A Comparison of Carrier-Based and Space Vector PWM Techniques for Three-Level Five-Phase Voltage Source Inverters

This paper describes a combination of direct torque control (DTC) and space vector modulation (SVM) for an adjustable speed sensorless induction motor (IM) drive. The motor drive is supplied by a two-level SVPWM inverter. The inverter reference voltage is obtained based on input-output feedback linearization control, using the IM model in the stator D-Q axes reference frame with stator current and flux vectors components as state variables. Moreover, a robust full-order adaptive stator flux observer is designed for a speed sensorless DTC-SVM system and a new speed-adaptive law is given. By designing the observer gain matrix based on state feedback H∞ control theory, the stability and robustness of the observer systems is ensured. Finally, the effectiveness and validity of the proposed control approach is verified by simulation results.

Novel Direct Torque Control Based on Space Vector Modulation With Adaptive Stator Flux Observer for Induction Motors

SUMMARY

In this study, a Z-source alternating current-to-alternating current (AC–AC) converter with a specific topology, which can provide both buck and boost modes, is investigated. This converter, which can be implemented easily, utilizes only two switches with complemented commands. A comparison between the Z-source AC–AC converter and a conventional thyristor voltage controlled one is presented here, and it shows that in the most areas, the Z-source converter provides a faster response and lower total harmonic distortion of the output currents than the conventional one. Moreover, the Z-source converter is also extended to the multiphase systems. In addition, a new arrangement of this converter is proposed here to remove the isolated single-phase sources. Furthermore, an open-loop method is proposed for soft-starting applications. Finally, a closed-loop control system is also suggested for a three-phase Z-source converter to soft start and control the speed of an induction motor. Computer simulations show the validity and effectiveness of the proposed schemes. Copyright © 2014 John Wiley & Sons, Ltd.

A new arrangement of Z‐source AC–AC converter and its closed‐loop control system

This paper presents a new direct active and reactive power control for DC–AC converters connected to three-phase network through a filter and lossless/lossy line. The control is based on adaptive input–output feedback linearization control (AIOFLC). The controller computes the reference voltages of the inverter to bring active and reactive power errors to zero without any inner current loop. With a suitable Lyapunov function, the control law and the estimation laws for inductance and resistance of filter and line are obtained in synchronous reference frame. The proposed controller has a simple structure which needs less computation and increases accuracy. Using space vector pulse width modulation (SVM), a fixed switching frequency is achieved which simplifies harmonic design of AC filter and more utilizes DC voltage source. The parameters of filter and line are uncertain or unknown; only their nominal values are available. Simulation results show the capability and effectiveness of the proposed AIOFLC in direct active and reactive power control in several case studies considering various unknown filter/line parameters.

Decoupled Active and Reactive Power Control of a Grid-Connected Inverter-Based DG Using Adaptive Input–Output Feedback Linearization

A modified reaching phase sliding mode controller for a speed sensorless induction motor drive using feedback linearization theory

This paper deals with control of a photovoltaic (PV) power generating single-phase system. The PV system consists of a DC-DC positive output super lift Luo (POSLL), a DC-AC converter, R-L filter and utility grid. The POSLL converter is used between PV panel and the DC-AC converter. A sliding mode control approach (SMC) using sign function is used for control of PV voltage and POSLL inductor current. The injected current to grid is also controlled by SMC method. To achieve maximum power point (MPP) of the PV panel, a maximum power point tracker (MPPT) known as perturb and observe (P&O) is employed. The MPPT provides reference of the PV voltage. For confirming the validity and the effectiveness of the proposed control approaches, a simulation by PSIM software under different operating conditions including various temperatures and radiations is presented and discussed.

Sliding mode control of single phase grid connected PV system using sign function

This study investigates a new double-stage single-phase Grid-Connected (GC) Photo-Voltaic (PV) system. This PV system includes a DC-DC Positive Output Super Lift Luo Converter (POSLLC) and a single-phase inverter connected to a grid through an RL filter. Due to its advantages, the POSLLC was used between PV panel and inverter instead of the conventional boost converter. The state space equations of the system were solved. By using two Sliding Mode Controls (SMCs), PV panel voltage and POSLLC inductor current were controlled and the designed controls were compared. Two of these SMCs included a simple Sign Function Control (SFC) and a conventional SMC. To control the power injected into the grid with a unity power factor, an SMC was used. Perturb and Observe (P&O) method was employed to reach maximum power of the PV panel. The Maximum Power Point Tracking (MPPT) control generated the voltage reference of the PV panel. Similar controls were used for the boost converter instead of POSLLC. The obtained results were compared.

Navid Reza Abjadi

Papers

A new arrangement of Z‐source AC–AC converter and its closed‐loop control system

Decoupled Active and Reactive Power Control of a Grid-Connected Inverter-Based DG Using Adaptive Input–Output Feedback Linearization

A modified reaching phase sliding mode controller for a speed sensorless induction motor drive using feedback linearization theory

Sliding mode control of single phase grid connected PV system using sign function

Applying Sliding-Mode Control to a Double-Stage Single-Phase Grid-Connected PV System