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This paper presents a new thermal protection approach for permanent magnet synchronous motor. Usually the thermal protection model is built based on two parameters which are thermal resistance and thermal capacitance of motor. But the stator core loss is increased significantly when the motor frequency and the motor winding temperature are increased. If the motor runs at high speed, the eddy current loss, the hysteresis loss and the harmonic current loss dominate the stator core loss. If only the thermal resistance and thermal capacitance are used for the thermal protection without considering the motor frequency, the protection model cannot response the temperature rising when the motor runs at high speed, so the motor could not be protected effectively. In this paper, the motor frequency is included in the new thermal protection approach, and the whole working speed range will be protected, and the motor lifetime will be increased.

This paper presents a novel approach to control power flow inside a high frequency transformer based multiport DC-DC converter. A multiport converter can interface a number of power sources and sinks with control of power flow among them. In a renewable energy sources (RES) integration scheme, the multiport converter operates like an accumulator where it collects power from each RES and dispatches it to the load port. Typically, power flow between any two ports happens through the leakage inductance of the transformer by imposing a required phase shift between fundamental component of two square wave voltages, impressed at the ports. However, each port is connected with the other ports by some inductance and hence the power flow from a particular source port to load port is not decoupled and can not be controlled independently. This paper proposes decoupling of source ports by eliminating the load port leakage inductance with a negative inductance, emulated by voltage injection in series with leakage inductance. A three port transformer based system is simulated to validate the principle. A scaled prototype of the three port transformer is designed and the effect of load port leakage inductance is analyzed through experiment.

The current imbalance in driving LED strings will cause fast degradation or even failure in some LEDs that should be avoided in LED applications. This paper presents a current balancing method based on the pulse-width modulation of a common bus voltage to each LED string to achieve the intended averaged current. For the balance of a common averaged current, a small duty cycle will necessitate a large LED turn-on current amplitude, which may cause temporal overheat and low luminous efficacy of LEDs. An optimal feedback control scheme is proposed to maximize the duty cycles and minimize the bus voltage. As a result, at lease one of the LED string is operating at a unity duty cycle. The analysis, implementation and verification are detailed in this paper.

This paper presents research motivated by industrial demand for special novel high voltage traction drive topology devoted to minimization of traction transformer weight against classical locomotives operates on both 25kV/50Hz and 15kV/162/3Hz trolley voltages. This paper deals with testing of whole traction converter prototype in configuration: two single phase matrix converter + medium frequency transformer + single phase voltage-source active rectifier in selected transient states and verifying of proper function of control algorithms. The new control of traction converter based on inserting zero vectors has been proposed to smooth taken trolley current.

This paper proposes a weighted Real-Time Digital Feedback Control for a grid connected Distributed Generation (DG) system (gas turbines, fuel cells, photovoltaic, wind.). The DG source is connected to the grid through a Power Conditioning Unit (PCU) consisting of a multilevel Flying Capacitors Inverter (FCI), an inductor, and a step-up transformer. The proposed controller is predictive type offering the possibility of furthering the capacitor voltages tracking, load current tracking, or a trade-off between all state variables tracking (capacitor voltages should be controlled in order to ensure a proper operation of the FCI). The Weighted Predictive Controller (WPC) transfers the power to the grid, even under grid voltage variation (sag or swell) due to its Voltage Ride Through (VRT) capability by controlling the current with unity power factor. Theoretical analysis, simulation and experimental results are described in this paper. © 2013 IEEE.

This paper presents a novel half-circle-shaped tubular linear permanent magnet machine named as “circular shaft motor (CSM)” for direct-drive applications. A CSM is a kind of the tubular synchronous actuator. Both the stator and the mover of a CSM are bent in a circle. A CSM can realize the motion along the circumference of a circle. In this paper, the design of a circular shaft motor is described. The prototype of CSM is introduced. Then, the measurement experimental results of the thrust characteristic are demonstrated. The utility of the developed CSM is confirmed from the results.

Intelligent control approaches for smart low voltage (LV) grids have to meet the future requirements caused by increasing penetration of decentralized generation (DG) from renewable sources and new network participators like electric vehicles. These technical requirements can be solved, but especially in LV networks it is necessary to consider the cost benefit ratio. This paper will therefore focus on active control approaches investigated within the research project “DG DemoNet - Smart LV Grid”. By using an existing Smart Grid metering infrastructure and pursuing the long-term objective of a “plug&automate” solution, the mentioned challenges should be solved with acceptable costs regarding investment, maintenance and operation. In this paper the proposed control concepts for the transformer's on-load-tap-changer (OLTC) are in detail discussed along with first experiences from simulations of some of these concepts.

Power Electronic Transformers (PETs) have been proposed for future power distribution systems as well as for use in adjustable speed drives where space and weight are at a premium. This paper investigates the commutation of Matrix Converter (MC) based PETs where finite leakage inductance is present at the input of the matrix converter and it is no longer purely a voltage port. A PET with reduced number of switches on the primary side is selected for the presented research. This paper compares modulation based on carrier comparison and space vector along with commutations using four-step and dead-time. All these combinations of modulation and commutation are implemented efficiently in a single FPGA chip and some of the experimental results are presented.

In recent years, air hygiene became an increasingly important topic of research. Due to the use of very efficient insulation methods, many new and refurbished houses have a reduced air flow caused by missing leakages. If these houses are not ventilated in the correct way, mold formation can be caused. This paper describes a recently developed controllable air passage, which can be integrated into window frame extensions and that allows circulation of sufficient air inside rooms to prevent mold formation. The main requirements for typical air passage systems are introduced. Most technical requirements are based on the new DIN 1946-6 standard, which regulates e.g. the minimum air exchange rate of buildings to guarantee their air quality. Further requirements, for commercial viability of the system, are also described. To meet these requirements, the system was segmented in different modules. For each module, several options for hardware implementation were tested. The most promising are presented in this paper, including simulation and test-measurement data. Also, the simulation results of an apartment with installed air passage systems are included.

This paper analyzes the impacts of reactive power injections by PV inverters on thermal performances of their components. The analysis is focus on three weakest components in PV inverters, namely, IGBTs, diodes and a DC link capacitor. Reactive power injections cause additional losses such as conduction losses and switching losses in IGBTs and diodes and conduction losses due to double frequency current ripples in a capacitor. These losses cause temperature rise in the devices. This paper simulates the thermal performances of PV inverters using PSIM software and verifies the results using analytical expression of conduction and switching losses. It is found that reactive power injections cause additional temperature rise in all the devices. Leading power factor operations result in a slightly higher temperature rise in IGBTs and diodes than lagging power factor operations.

This paper presents an electronic ballast topology intended for operation of high intensity discharge lamp (HID). The presented HID lamp ballast integrates a voltage-fed quasi-Z-source inverter with continuous input current (qZSI) as power factor corrector (PFC) with a high/low-frequency square-wave-driven full-bridge inverter for supplying low-frequency square-wave sources to the HID lamp. The features of the proposed ballast are high power factor, continuous input current and it is free of acoustic resonance. This paper analyzes the operational modes, design guidelines and experimental results of the proposed ballast for a 250W HID lamp.

In this paper control systems suitable for a 4-leg NPC converter are discussed. The proposed control methodology is based on a finite set model predictive control. A theoretical analysis of the strategy, including tracking of non-sinusoidal currents and reduction of the switching frequency, is presented in this paper and experimental results, obtained with a 3 kw experimental prototype are discussed.

Contactless power transmission (CPT) technique based on the contactless transformers is extraordinarily promising for the electrical vehicle (EV) battery charging application for its safety, convenience and flexibility. By introducing two parallel windings into two EV CPT charging systems so as to constitute two cascaded contactless transformers, a novel contactless bidirectional resonant converter (CBRC) is proposed in this paper. Based on which, an emergency battery charging system is also presented. The equivalent circuit of the cascaded contactless transformers and the topology of the CBRC are analyzed and discussed in this paper and the series-series compensated double full bridge CBRC is finally adopted as the main circuit. This paper takes a thoroughly study on the control strategies for the proposed CBRC. After proposing and analyzing three possible control methods, primary constant frequency plus secondary PWM control and primary PLL and PWM control are adopted. Finally, an 1800 W CBRC prototype with two control methods is fabricated to verify the theoretical analysis and the effectiveness of the proposed control strategies.

The paper assesses the torque capability of high phase induction machines taking a conventional three phase machine as the basis for comparison; analytical expressions for torque as a function of phase number for machines with sinusoidal and trapezoidal airgap field are derived and discussed. A trapezoidal field is assumed to be produced through the imposition of a third harmonic current in the stator current besides the fundamental. The torque capability comparison is performed keeping the airgap peak induction and the linear stator current constant, thus resulting about the same amount of magnetic and winding losses for variable phase number. It is shown that the main factors influencing the torque capability of machines with sinusoidal airgap field are the winding characteristics - including number of slots per phase and pole - and the winding pitch. Higher torques are associated with windings without pitch shortening and with low values of slots per phase and pole. It is also shown that machines with trapezoidal field can have higher torque capability than sinusoidal field machines, being the greatest torque improvement associated with low values of slots per pole and phase. Under the assumptions made, torque improvements from 10% to 15% can be obtained. The paper also shows that for sinusoidal field machines, the maximal torque practically obtained with seven phases, while for trapezoidal field the maximal torque is obtained with eleven phases.

This paper investigates universal start-up procedure for Flying Capacitor Converter (FLC). Main part of this procedure is pre-charging of the dc-link and flying capacitors. This method is usable for voltage pre-charging in rectifier as well as inverter mode of the multilevel FLC converter. This specific feature is based on use of converter topology and modification of converter switching pulses control. The proposed control improvements are designed to control particularly multilevel converters. The control system is implemented in development platform Multi Level Converter (MLC) interface for a four-level multilevel converter with flying capacitors. Its performance is investigated and evaluated by selected experiments made on a developed converter prototype of the rated power of 30 kVA. This paper also discusses behaviour of converter on occurrence of safe restart and shut-down procedure.

The paper discusses the influence of a grid impedance, especially for a leakage inductance of a grid side transformer. The grid impedance does not usually take into account during the design stage of the current controller. As a result, low order harmonics in the grid current are distorted. In this paper, the active feed-forward compensation method is proposed for the purpose of attenuating the current distortion. The proposed method can be applied to L filter as well as LCL filter. The effectiveness of the method is verified through various simulations and experiments based on a 1.5kW voltage source inverter prototype.

This paper proposes a novel time-delay compensation method for multi degree-of-freedom bilateral control system with different configuration. Bilateral control is a remote control technology, which enables transmission of force sensation. Time-delay is the one of the problems of the bilateral control, because it degrades the transparency and stability of the control system. Communication disturbance observer (CDOB) has been proposed to compensate time-delay without dead time model. However, CDOB cannot compensate time-delay if the bilateral control system has different configuration and is controlled in work space. Therefore, this paper proposes a novel observer, work space communication disturbance observer (WCDOB), for time-delay compensation. The proposed method can compensate time-delay if the bilateral control system has different configuration and is controlled in work space. Experiments were conducted by using actual network. The experimental results show the validity of the proposed method.

In this paper, the pre-design methodology of a monolithic Inter Cell Transformer (ICT) in parallel multicell converters is presented for normal operation and with a reduced number of phases. The goal is not to saturate the active phases when the number of cells is reduced. An analysis and comparison of monolithic ICT have been conducted in these two configurations. The increased volume and mass of the robust monolithic ICT is very important for low number of cells. Air-gaps have been inserted in order to limit this augmentation. These air-gaps balance and reduce the overload flux density in active cores during the post-failure operation. In order to validate the theoretical results, a ladder structure of a 6-phase monolithic ICT and a reconfigurable converter has been built. The experimental results for the prototype will be presented by the authors in their next paper.

The electromagnets in modern particle accelerators require high performance power supply whose output is required to track the current reference with a very high accuracy (down to 50 ppm). This demands very high bandwidth controller design. A converter based on buck converter topology is used in this paper. The paper presents a model of the converter which enables the design of high performance controller using a proportional-integral controller and a feedforward gain. Experimental and simulation results are presented with resistive and inductive load which verify the system requirement using the proposed approach of the system model and controller design. The electromagnets in modern particle accelerators require high performance power supply whose output is required to track the current reference with a very high accuracy (down to 50 ppm). This demands very high bandwidth controller design. A converter based on buck converter topology is used in this paper. The paper presents a model of the converter which enables the design of high performance controller using a proportional-integral controller and a feedforward gain. Experimental and simulation results are presented with resistive and inductive load which verify the system requirement using the proposed approach of the system model and controller design.

In this paper a matrix converter modulation adapted for the wind energy conversion system of series-connected turbines is presented. The considered conversion system is composed of a permanent magnet synchronous generator, a matrix converter, a high frequency transformer and a diode bridge rectifier for the AC-DC conversion. This conversion system topology allows for a modification, introduced in this paper, of the indirect space vector modulation that increases the current ratio of the matrix converter and thus enhances its advantage for this wind park configuration. The modulation can be further modified into a square wave modulation for high frequency operation of the transformer. An efficiency analysis of the suggested modulation and its high frequency version is performed. Also some attention is given to the flux balance issue in the transformer and a possible solution for a modulation yielding balanced flux is given.

In this paper, a predictive torque control (PTC) algorithm is introduced for controlling an induction motor (IM) fed by a bidirectional quasi Z-source inverter (BQZSI). A torque, stator flux and capacitor voltage magnitudes control algorithm evaluates a cost function, based on a simple discrete models of the IM and the BQZSI, for each BQZSI available switching state. The voltage vector with the lowest torque, a stator flux and capacitor voltage magnitude errors is selected to be applied in the next sampling interval. The proposed PTC algorithm, with its single structure, can control both sides of the BQZSI to optimize the motor performance with an extremely simple and versatile control algorithm and without any dynamic response limitation caused by the cascaded control structure. A high degree of flexibility is obtained with the proposed control technique due its online optimization algorithm. This paper proposed a new adjustable speed drive system based on a three-phase BQZSI feeding an induction motor. Where, the interesting advantages of the PTC algorithm are combined by the advantages of one of the most interesting power electronics converters, the BQZSI. Simulation results for a 4 kW IM are presented to validate the new proposed electrical drive system.

This paper compares the distributed winding and concentrated winding IPMSMs designed for direct-drive wind turbine. Apart from different stator winding configuration, the two IPMSMs have identical rotor and stator dimensions, air gap length, magnet length and stack length. The paper also discusses various techniques that were applied to minimize the cogging torque and torque ripple.

This paper describes a MRAS-based sensorless control of a high-speed squirrel cage induction machine connected to the grid. This paper contributes with the subject when using a high-speed machine supported by active magnetic bearings (AMB) for energy applications. This kind of system is suitable for energy generation from gas sources. To control the grid side as well as the generator side a back-to-back converter with voltage oriented control (VOC) and rotor field oriented control (RFOC), respectively, is used. Simulations are presented for the MRAS observer, and some experimental results are also showed. A test bench was designed and the final experimental results are undergoing.

This paper proposes a control strategy for high power factor without electrolytic capacitor in home appliance. The proposed system consists of single-phase diode rectifier, small film capacitor (20uF), three-phase voltage inverter and AC motor. In order to obtain a high power factor, this paper proposes a new control method that delays q-axis current compared with phase of grid voltage. The method is based on the field-oriented control, PI controller, quasi-PR controller and space vector pulse width modulation (SVPWM). The simulation and experimental results illustrate the validity of the analytical approach and the efficiency of the proposed method.

The significant improvements that have been recently achieved in HBLEDs technology in terms of lifetime, luminous efficacy, and power rating, make these devices one the most promising candidates to replace conventional light sources in various residential and industrial applications, despite their high cost. The efficiency requirement should be completed by means of the voltage conversion stage by performing Power Factor Corrector. In this paper we consider the problem of Power Factor Corrector and output current regulation for a group of HBLEDs by using a Cuk converter under a Sliding-Mode Control which must be ultimately implemented by a hysteretic comparator to limit the switching frequency to practical values. However, with a constant hysteresis width, the system exhibits harmful harmonic distortion in the input line current waveform. Therefore, a variable hysteresis window is used thereby avoiding this distortion near the zero crossing of the input current. Using the Cuk converter under a Sliding-Mode Control with variable hysteresis window, the converter will be forced to behave as a Loss Free Resistor. Simulation and experimental results are presented in this paper to demonstrate the functionality of the proposed technique.

In the present paper, a novel topology for generating a 17-level inverter using three-level flying capacitor inverter and cascaded H-bridge modules with floating capacitors. The proposed circuit is analyzed and various aspects of it are presented in the paper. This circuit is experimentally verified and the results are shown. The stability of the capacitor balancing algorithm has been verified during sudden acceleration. This circuit has many pole voltage redundancies. This circuit has an advantage of balancing all the capacitor voltages instantaneously by switching through the redundancies. Another advantage of this topology is its ability to generate all the 17 pole voltages from a single DC link which enables back to back converter operation. Also, the proposed inverter can be operated at all load power factors and modulation indices. Another advantage is, if one of the H-bridges fail, the inverter can still be operated at full load with reduced number of levels.

This paper proposes a current harmonic reduction method to improve the input current waveform in electrolytic capacitor-less single-phase to three-phase power converters. Typically, the back EMF of an IPM motor is not sinusoidal and contains harmonics caused by the rotor structure; therefore, it causes harmonic distortion in the motor control system and generates harmonics in the input current. In this study, the cause of the input current harmonics induced in the back EMF and the d-q axis current controller are analyzed. Furthermore, this paper proposes a control method to reduce the current harmonic distortion. In the proposed method, the d-q axis voltage references are compensated to reduce the input current harmonics. The d-q axis compensation voltages are obtained by a feed-forward controller. The maximum power factor obtained by the proposed method is 98.0[%]. The experimental results confirm that the proposed control method conforms to the EN61000-3-2 guideline.

This paper proposes a new control method for a multi-motor drive system to increase its output torque capability and extend its operating speed range. When the drive system is operated below rated speed, the motors are parallel operated to increase total output torque. By suitably distributing the stator currents based on an optimal efficiency algorithm, the output torque can be effectively increased. On the other hand, when the drive system is operated beyond rated speed, one motor is operated at a standstill and its stator inductances are used as three-phase inductances of an boost converter; moreover, an interleave control algorithm is used for the boost converter to reduce the input current ripples. The other motor is used as a driving motor. By using this method, an extended speed, which can reach twice the rated speed range with a near constant torque, is obtained. No field weakening is required. This paper proposes a new control method for a multi-motor drive system, which can be applied to electric vehicle drive systems.

This paper investigates two zero power control methods for a spiral motor, which are current integral type and external force feedback type. A spiral motor is a linear motor having helical mover and stator that can realize a high thrust force density and high back-drivability. In latest researches, the magnetic levitation control, position control and force control were archived. Additionally, power-saving magnetic levitation is successful by a zero power control. However, a response time of the force control is delayed by the zero-power controller. This paper presents a comparison between zero power control methods through simulations and experiments. As a result, on the force control, external force feedback type zero power control is able to improve the transition time than the conventional method.

This paper presents the dynamics of wind-turbine driven Self Excited Induction Generator (SEIG) with the consideration of dynamic core losses and dynamic mutual inductance. The core losses when considered are often taken as function of air-gap voltage and very few researchers included the variation as function of stator synchronous frequency. Similarly in most of the cases mutual inductance is taken as constant which is a simplified version of true dynamics. In this paper simulation studies are carried out to assess the dynamic performance of SEIG considering both the core losses and mutual inductance as dynamic variables. The performance is assessed in presence of variations in rotor speed, simulated as wind's effect, by a simplified wind turbine model. It is observed that dynamic mutual inductance and dynamic rotor losses are important parameters for accurate voltage and current measurements.

International audience; Electric vehicles rise new issues, among them high frequency noise, that are coming from electric powertrain. This noise is caused by interaction between magnetic radial forces and mechanical stator structure. Current harmonics may excite stator natural frequencies, thus leading to vibrations responsible for acoustic noise. In this paper, we propose a new method based on control to reduce current harmonics. They are modeled as the consequence of a sinusoidal disturbance at a given frequency. This is estimated by an observer and this estimation is used to cancel harmonic components contained in stator currents.

Large LED (light-emitting diodes) clusters are currently designed to replace the commonly lamps used in parks, roadways, tunnels and street lighting. But the success of these designs is heavily dependent of the high performance of the thermal management. Thermal performance affects the light extraction, reliability and the lifetime of LED lamp. This paper proposes a solution to improve thermal design of LED luminaires. This solution uses a forced air convection into a closed cooling loop. Simulations employing Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) have been done to evaluate the system performance and to propose improvements in the airflow design. Comparisons of the experimental and simulation results are presented for validation.

A new soft switching resonant converter is presented in this paper to reduce the switching losses on power MOSFETs and overcome the reverse recovery losses on rectifier diodes. Two half-bridge legs connected in series and two split capacitors are adopted to limit the voltage stress of each MOSFET at half input voltage and to reduce the current rating of transformer windings and passive components at output side. A flying capacitor is connected between two half-bridge legs in order to automatically balance two input capacitor voltages. Therefore, MOSFETs with low voltage stress can be used at high input voltage applications. The resonant converter is adopted in each half-bridge circuit to reduce the switching losses of active devices. Finally, experiments based on a laboratory prototype are provided to verify the circuit performance.

A novel model reference adaptive system based stator resistance estimation algorithm has been proposed in this paper. A new functional candidate is introduced which is positive definite and does not depend on speed information for resistance estimation. This formulation decouples stator resistance and speed estimation in case of a Q-MRAS based sensorless drive. Also, restriction on selection of estimator gains becomes less rigid when the proposed estimator is used for stator resistance compensation in an X-MRAS based drive. Extensive simulation using MATLAB/SIMULINK and experimentation in dSPACE 1104 based laboratory prototype has confirmed the effectiveness of the proposed technique.

This paper presents design issues and realization of a common mode (CM) electromagnetic interference (EMI) filter for a DC-supplied motor drive equipped with an output active CM voltage compensator. The obtained system allows both reliability and EMI of the motor drive to be improved at the same time. In particular, as for reliability, the active CM voltage compensator gives a reduction of the stress on motor bearings; in addition, the input EMI filter, designed taking into account the impedance mismatching between EMI source and receiver in the actual circuit configuration, allows standard limits to be satisfied. Simulation analysis and experimental assessments are given.

Doubly Salient Electromagnetic Machine (DSEM) is fundamentally a new type of variable reluctance machine, whose operation principle is different from the conventional AC electrical machines. Analysis of operation principle, magnetic field and loss distribution characteristics of DSEM is important and necessary. This paper has analyzed the magnetic field distribution of Doubly Salient Electro-magnetic generator (DSEG) comprehensively and proposed a method separating DSEG into eight parts to describe the distribution characteristics of iron loss. In order to predict the iron loss of DSEG accurately, Fourier Transform is used to analyze the magnetic flux density of each part. A calculation model of iron loss is established, whose coefficients are determined by the measured data of a 24/16-pole DSEG at different speed. The relationship between the eddy-current loss and hysteresis loss is emphasized as well as the distribution of iron loss of each part. Moreover, the influences of speed, air-gap length as well as field current on iron loss are summarized and analyzed. Finally, the calculation and analysis of iron loss are verified through experiment results.

This paper presents the preliminary design of a 10 MW permanent magnet synchronous generator (PMSG) for off-shore direct drive wind turbines (DDWT). In order to improve the DDWT torque quality, energy efficiency, power management, fault tolerance and reliability a twelve-phase PMSG made of four independent three-phase star connected subsystems has been considered. With the aim of satisfying the several constraints related to cogging torque reduction, stator and rotor diameter limitation, low speed operation and magnetic decoupling of four three-phase subsystems, a multi-star fractional-slot tooth concentrated winding PMSG has been designed. The analytical results have been validated by means of Finite Element Analysis (FEA) highlighting the worth and effectiveness of the proposed configuration.

Since Fuel Cells (FCs) are very expensive, their output power should be minimized when FCs are applied to hybrid powered railway vehicles. Therefore, it is necessary to reveal the effect of hybridization with energy storage devices to reduce the FCs output power. In this paper, methods to design the capacity of energy storage devices which are assumed to be Lithium-ion batteries (LIBs) and Electric Double Layer Capacitors (EDLCs) are studied for FCs hybrid powered railway vehicles. The proposed methods are verified by numerical simulations, assuming a train operation in a typical rural line. Finally, procedures to select the suitable energy storage devices and to design their capacity for FCs hybrid powered railway vehicles are provided. The results of this study contribute to the development of environment-friendly transportation system.

In this paper, a sensorless artificial neural network (ANN) speed control strategy of permanent magnet synchronous machines (PMSMs) is introduced as an alternative to conventional control techniques. The control strategy achieves accurate tracking by making use of ANN's learning capabilities to approximate the machine's nonlinear dynamics. On the other hand, an ANN-based observer is used to estimate rotor speed and the rotor position is obtained by direct integration to reduce the effect of the system's noise. Unlike other sensorless control strategies, no a priori of œine training, weights initialization, voltage transducer or mechanical parameters knowledge is required. Furthermore, the stability of the overall closed-loop system is proved by Lyapunov stability theory. The controller is compared to the well-known vector control technique. Results for different situations highlight the higher performance of the proposed control approach in transient, steady-state, and standstill conditions.

Methods of sensorless control of PMSM drives are commonly divided into model-based and high-frequency injection based approaches. Each of these approaches uses a different algorithm for estimation of the rotor position and speed. Typically a Kalman filter is used for the model-based approach and phase-locked loop (PLL) for the hf injection based approach. In this paper, we show that the PLL is a steady state solution of the Kalman filter for a special state space model. Since this model has a commonly used state equations, we can easily combine the observation equations from the model-based approach with those from the hf injections. Several possibilities of combination are described and tested in the paper.We illustrate properties of these algorithms on experimental data in sensored mode. Sensorless control strategy based on the presented models is demonstrated on a laboratory prototype of surface mounted permanent magnet synchronous motor (PMSM) drive of rated power of 10.7kW.

Wind power generation as well as hydrogen energy have attracted much attention as a solution for solving the energy problem in the future. Though many strategies for the operation of a grid-connected wind farm have been proposed, operation method of stand-alone wind farm has not been studied sufficiently so far. There are many places with good wind condition but without connectable grid, where stand-alone wind farm can be very attractive. This paper proposes a stand-alone hydrogen production system composed of wind generators and hydrogen electrolyzer.

A Takagi-Sugeno neuro-fuzzy inference system for direct power control of a doubly fed induction generator is presented in this paper. The control variables - d-axis and q-axis rotor voltages - are determined by a control system that consists of a neuro-fuzzy inference system and a first order Takagi-Sugeno fuzzy logic controller. To validate the proposed strategy, experimental tests are made for the DFIG operating speed is slightly less than the synchronous speed. The operation of the generator with abrupt and linear changes in stator power and under variable or constant speeds are tested.

This paper presents an analytical analysis and application of axial flux permanent magnet machine design to marine current turbine. Marine current is a prominent renewable energy source because of its predictable current profile. Rim-driven, direct-drive type is favorable for the marine current turbine application in terms of maintenance and reliability. The axial flux permanent magnet machine is a candidate machine type that not only reduces machine manufacturing costs, but also achieves high performance. The general sizing equation technique is implemented to produce the machine size. The magnetic flux relationship among air gap, stator yoke, rotor yoke, and permanent magnet is taken into account to calculate core material size of the machine. FEA simulation results are compared with analytical calculations. The proposed machine and the reference machine design results are briefly compared. Moreover, machine cost is estimated based on the volume of the proposed machine.

This paper proposes the design of switched reluctance motor (SRM) to obtain high motor efficiency. The first step of design makes the principle improving motor efficiency clear. The cross sections and axial shapes of rotor and stator cores are designed by using the magnetic field analysis with 2D and 3D finite element methods. The designed SRM is produced experimentally, and is tested to certify the performance.

In this paper, a thorough analysis of the reverse conduction characteristics of vertical trench (VT) Silicon Carbide (SiC) junction field effect transistors (JFETs) is performed. While these power devices do not encompass a body diode, traditionally present in conventional Silicon (Si) based semiconductors, such as the metal-oxide semiconductor field-effect transistors (MOSFETs), they exhibit notable reverse properties such that an external antiparallel diode can be considered redundant in most power converter applications. Both enhancement mode and depletion mode SiC JFETs are examined in terms of static reverse operation. Their performance is initially validated through simulation testing by constructing new SiC JFET models in Pspice model editor. The theoretical and simulation results are confirmed via experimental testing in a three phase voltage source inverter with and without antiparallel SiC diodes. When a gate drive that protects the semiconductor during reverse operation, while presenting great switching and forward conduction characteristics, is introduced, the power converter's overall performance is investigated paying particular attention to power losses during the dead time interval.

The nearest level modulation is the simplest and most practical method for a modular multilevel converter due to its large number of sub-modules. Traditional nearest level modulation ignores voltage fluctuation of a capacitor, when it calculates the number of inserted sub-modules. This will cause errors between the actual voltage generated by sub-modules and its reference. These errors will lead to the fluctuation of circulating currents and additional losses. This paper proposes a zero tracking error nearest level modulation, which can eliminate the errors. This method is validated by 71 voltage-level modular multilevel converter simulation results.

This paper presents a robotic welding teleoperation system that can learn the skilled welder's behavior and transfer human intelligence into welding robots. In this system a 6-DOF robot arm is equipped with a compact 3D weld pool sensing system. The motion of the human welder movement is tracked accurately by the Leap sensor. A predictive control algorithm is proposed to control the speed of the robot arm movement. Tracking experiments are conducted to track pre-set movement with varying speed and human hand movement. It is found that the robot with the proposed speed control algorithm is able to track human hand movement with acceptable accuracy. A foundation is thus established to realize welding teleoperation and transfer human intelligence to the welding robot.

The purpose of this paper is to present a real time wind simulator and it's different uses. Given the fact that the simulator is based on a doubly fed induction generator, one of the uses can be the study of different aspects of grid connection and impacts of different faults that may occur in normal operation of wind systems. The studied system is a variable speed wind turbine system with a Doubly Fed Induction Generator (DFIG). The stator of the generator is directly connected to the grid while the rotor is connected through a back-to-back converter which is dimensioned to stand only for a fraction of the generator rated power. The simulator is developed using Hardware-in the-Loop techniques and in order to provide the static and dynamic characteristics of a wind turbine system. We analyzed and developed an experimental system consisting of two main parts: a real time software simulator and an electromechanical system. The Electromechanical System is composed from three electrical drives: an asynchronous machine that emulates the wind turbine, an asynchronous generator, used to study the energy conversion and grid connection problems. The Software simulator is a supervising and control subsystem and is composed from a computational unit and different interface devices. This subsystem is designed equally to study the capability of the classical network to support wind turbine penetration and grid faults impacts. Experimental results from the simulator are presented in order to compare different simulation procedures.

This paper presents a detection method for single open-phase fault in three phase permanent magnet synchronous machine. The method is based on predictive stator current calculation. For each sampling interval the difference between actual stator current and its predicted value in previous sampling interval is calculated. The magnitude of the difference serves as a main diagnostic index for single open-phase fault detection. By analyzing the angle of stator current the fault location can be identified. After the fault is detected and identified, if possible, the operation with reduced number of phases is desirable. For this purpose, single open-phase fault identification and post-fault operation will be briefly discussed. Fault detection method has been simulated in MATLAB and tested on experimental setup with a real machine.

This paper introduces a hardware-efficient controller for rectifiers with power factor correction (PFC) that feature circuits for cancellation of the output voltage ripple at two times the line frequency. It provides simultaneous and independent regulation of the ripple amplitudes and dc voltage values for both the PFC stage and the cancellation circuit, allowing for the tradeoff management between the overall system volume and its efficiency. Unlike previous solutions, the controller does not require costly components for obtaining information about the output current, converter parameters, or phase and frequency of the voltage ripple. These advantages are obtained through the hardware sharing and use of a novel two-band compensator. The effectiveness of the controller is demonstrated on a 45 W programmable-output flyback based PFC rectifier prototype with a buck-boost based ripple cancellation circuit. The results demonstrated achieves a 1% ripple for the full range of operating conditions with maximum of 90% ripple reduction while utilizing a 500uF output capacitor for PFC, providing high power factor and low harmonic distortion.