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Many multiple degree-of-freedom (DOF) motors have been researched. However, there are few sensors for multiple DOF position detection. If multiple DOF position is detected by several 1DOF sensors, the machine gets bigger and more complicated. To solve this problem, this paper proposes a new resolver for helical 2DOF position detection. Proposed resolver has stator part, mover part, excitation coils, and position detection coils for 2DOF position. Detection coils are arranged alternately in a helical direction. Therefore, proposed resolver can detect helical position. Based on detection of helical motion, proposed resolver can detect linear and rotary position. This paper introduces the structure of proposed resolver and principle of position detection. In addition, the simulation is conducted to confirm that the resolver can detect helical positions, linear position and rotary position.

This paper presents an intelligent indirect field oriented control (IFOC) technique for saturated induction motor (IM) drives in order to achieve high dynamic performance and wide operating range. The IFOC of IM drives has been traditionally carried out using linear proportional-integral (PI) controllers. As an IM is a nonlinear device due to the saturation phenomenon, conventional PI-IFOC methods provide poor performance, limited disturbance rejection capability and longer convergence time. The artificial neural network (ANN) has been widely used as an intelligent controller for nonlinear systems. ANN provides an adaptive learning ability to the controllers to better characterize the system dynamics for achieving accurate and fast responses. However, due to the iterative nature of neural networks, training of the ANN is excessively slow for saturated IM drives. In this paper, a novel neural network map (NNM) is developed to find input weights of the neurons; without the need for any recurrent training process. The proposed technique is applied on a 3-phase 4-pole 208V ¼ hp IFOC-IM drives. Both the simulation and experimental investigation have been carried out for the same motor drive, and the results are depicted and analyzed in this paper. A relative comparison between the PI controller and the proposed NNM based ANN controller indicates that the ANN mapping controller yields superior performance.

Distributed energy management algorithms eliminate the control center from the conventional energy management systems and calculate the optimal schedule for all devices through iterative coordination among neighbors. Most of the existing distributed approaches are developed under the assumption that all devices are secure and willing to achieve an optimal system performance together in a “collaborative” environment. However, unexpected faults and adversaries may emerge in the network and disrupt the convergence of those distributed approaches. In this paper, we extend the cooperative distributed energy scheduling (CoDES) algorithm to improve its resilience against data integrity attacks. Two types of data integrity attacks are considered in this paper - faulty attacks and random attacks. A distributed attack detection algorithm is developed to verify the state of neighboring devices without infringing their private information. A reputation-based mitigation algorithm is introduced to identify the compromised device and act accordingly to maintain the optimal energy scheduling result. The effectiveness of the proposed resilient distributed energy scheduling algorithm is evaluated in the Future Renewable Electric Energy Delivery and Management (FREEDM) microgrid system.

Ultrasonic energy transmission (UET) will become novel measures to power the devices under deep seawater, because the energy can be transmitted in the form of conductive contactless. But a long cable must be often required to transmit high frequency electric energy from platform to ultrasonic transducer (UT) for producing ultrasonic energy. However, the input impedance of UT would not match with the characteristic impedance of the long cable. Therefore, the energy transfer effect will be affected by the reflected wave produced in the joint position. In order to eliminate the reflected wave, the impedance matching method between long cable and UT was studied in this paper. A symmetric T type or Π type two-port matching network was designed by means of one-quarter wavelength cable. By this method, the capacitive UT impedance can be transformed into the resistive impedance, which equals to the characteristic impedance of the long cable. Hence, the reflected wave in long cable would be ignored. In the paper, the calculating formulas of inductance and capacitance in the matching network were derived based on the series expedition of hyperbolic functions in the transmission line equations. The experiments were made to show the effectiveness of the method.

This paper describes a balance sensing method based on point cloud information obtained from image feature tracker for biped walking robot. The dynamic equilibrium of walking robot is popularly acquired by force/torque sensors as the reaction force/moment from ground environments. On the other hand, in this paper, assuming the mechanical elastic model around foot sole or ankle, the equilibrium is obtained from the field view deviation of mounted camera image due to the elasticity around foot sole. The camera view movement is calculated from the point cloud data generated by image feature tracker in our approach. By using the vision-based balance sensing, the force sensor-less implementation can be considered for low cost design of biped robot, and also the sensor fusion or combined use with force sensor information will make an performance improvement in terms of sensing reliability. The proposed approach is evaluated by several experimental results.

Due to its great productivity, Gas metal arc welding (GMAW) has been become the most frequently used automated welding process. Unfortunately, the metal transfer changes from solid to liquid, which causes spatters and fumes. As a result, the process is complicated and needs to be controlled for good welding quality and good process stability. In return, the fumes, spatters and energy consumption will be reduced. This paper aims at establishing the ability of monitoring the metal transfer process in the real welding environments for the automated welding robot to control the welding process on line. In this paper, we designed a compact and practical monitoring system to measure the metal transfer of gas metal arc welding (GMAW) robustly. To this end, the captured images are modeled and effective image processing algorithms are proposed. Experimental results verified the effectiveness of the proposed algorithms and the designed monitoring system.

Inductive Power Transfer (IPT) has proved its capability as a safe, convenient and efficient solution for electric vehicle (EV) charging systems through loosely coupled transformer. Transformer with double-sided windings is expected to be more compact and lightweight than transformer with single-sided windings. In this paper, a solenoid double D (SDD) coil is proposed to have a good interoperability with the double D (DD) coil and the unipolar coil. To ensure high power transfer efficiency, tolerance for different gap variation and horizontal misalignment conditions are investigated in IPT systems. A 3D finite element modeling tool, Maxwell, is used to simulate all the models presented in this paper.

This paper evaluates the impact of manufacturing inaccuracies and aging on robust operation of distributed AC-stacked PV inverters. A novel index for analyzing the robustness of grid-tied AC-stacked PV inverter architectures has been used in this paper. Utilized index by considering four major operational characteristics such as conversion efficiency, Total Harmonic Distortion (THD), Maximum Power Point Tracking (MPPT) effectiveness and Power Factor (PF) compliance provides a comparative evaluation of PV inverters in different conditions and applications. Statistical analysis and Latin Hypercube Sampling (LHS) algorithm are used to model the impact uncertainties on robust operation of individual and AC-stacked PV inverters with minimum sampling point. Uncertainties which are considered in this paper are physical variations of passive components due to manufacturing inaccuracies and aging and also sensing inaccuracies. Boundary of robustness of grid-tied AC-stacked PV inverter architecture for each uncertainty is determined and compared with single inverter to verify the feasibility of the operation of grid-tied AC-stacked PV inverter architecture. Simulation and experimental results verifies the feasibility of the robust operation of Ac-stacked PV inverters.

Multilevel converters have gained popularity in both medium voltage and low voltage applications. To find out the connections between various multilevel voltage source converter topologies and reveal how to obtain new topologies, this paper has presented four methods to derive multilevel converter topologies. Many existing topologies as well as new topologies can be derived with the methods presented in this paper. The fundamental characteristics of the multilevel converters which determine their usability such as dc-link neutral point voltage balancing and flying capacitor voltage control are also investigated in the paper. It is expected that further topologies will be invented based on the work in the paper for emerging applications.

This paper presents a new approach to the solar tracking control. Today several methods are used to minimize the angle of incidence between the incoming sunlight and the photovoltaic (PV) panel. Most of them require optical solar sensor(s) to maximize energy output. There are approaches where geolocation data and the timetable of the Sun's position support a solar tracking mechanism. This paper proposes a novel sensorless (no optical or geo positioning sensors required) solar tracking mechanism based on a maximum power point tracking (MPPT) control for a mobile autonomous PV system. Such a system would provide an automatic PV panel position adjustment towards the Sun using a sensorless 3-DOF solar tracker system with a MPPT based control.

Wireless power transmission (WPT) has caused a radical change in the medical field, especially for medical implants. In this paper, a review of wireless power transmission history is given, its basic principle and it's very important role to load various medical implants such as cardiac, visual, gastric and endoscopic implants. The basic design of the WPT for each implant was been presented. This paper also outlines the safety consideration for human exposure to electromagnetic field.

This paper presents a new method to measure the phase dependent impedance from an experimental set up. Though most of power electronics based system is gradually migrating to IGBT based voltage source converter due to their controllability, the rectifier composed of diode or thyristor components are still widely used in AC-DC applications because of their cost effectiveness and reliability. However, these topologies generate harmonic problems in their network due to their switching instant variation caused by the frequency and phase of grid voltage. Hence, a lot of solutions have been proposed to provide an optimized solution for better power quality. However, the phase dependent impedance, which is driven by both switching instant variation and frequency coupling between ac and dc network, has not been treated in the design of passive filter or harmonic compensator design for power electronics application. It is found that the phase dependent impedance shows different properties with the impedance profiles, which have been proposed in the research. This paper explains a method to measure the phase dependent impedance profile from an experimental set up. Furthermore, the results are compared with results from time-domain simulations and results from an analytical model developed in the Harmonic State-Space (HSS).

This paper discusses the advancements in the development of the medium voltage solid state transformer (SST) based on 15 kV SiC MOSFET and JBS diode. Designed for 7.2 kV single phase distribution grid applications, the medium voltage SST converts high voltage AC to low voltage 240/120V ac. The use of ultra-high voltage SiC devices allows the simplification of the power conversion circuit topology. This paper presents the characteristics of the high voltage SiC MOSFET devices as well as the topology innovations to achieve ultra-efficient SST design. Specifically, three different designs are discussed which utilize three-stage, two-stage and single stage power conversion topologies to achieve the AC to AC conversion.

This paper presents some improvements over the previously presented current-shaping control for parallel active filters. The proposed strategy allows the active filter to operate with a reduced number of sensors, and dependently of phase synchronization schemes for references generation. A new realization proposal employs a quasi-resonant system frequency adaptable to implement complex impedances, and have low interaction with harmonic components in the grid. An additional quasi-resonant scheme in a stationary reference frame is proposed to extend the current shaping control in order to achieve great mitigation capability. The energy flow control in this paper deals with further uncertainties, which results in an enhanced robust design methodology. Experimental results are presented using a 1kVA prototype.

In the rise of the IoT era ambient-energy harvesting is expected to liberate networked embedded systems from the use of batteries. Several research efforts have already addressed in depth the perennial powering of embedded systems through energy harvesting, mainly focusing on WSNs. Super-capacitors offer a viable alternative for ambient-energy harvesting applications, demonstrating significant advantages and much longer operating lifetime over rechargeable batteries. This paper applies similar concepts to more powerful microprocessor-based unsupervised wireless mobile embedded systems that can be accessible anywhere over a short burst satellite connection. AITHALES is a power-autonomous batteryless M2M satellite tracking embedded system harvesting ambient solar, thermal and vibration energy and storing it in a super-capacitor which supplies uninterrupted power to the tracking unit. The system was developed in the context of a container tracking application for container operators to tackle the problem of container loss, but serves as a paradigm for autonomous outdoor monitoring systems required to operate uninterrupted under often harsh environmental conditions and without periodic user intervention. The paper concludes with a feasibility study of powering the system from multiple ambient energy sources (solar, thermal and vibrations) and proves that performance is adequate for completely unsupervised system operation.

This paper proposes a novel, simultaneous bipedal locomotion method with the use of human skill of walking, to increase the performance of walking of the biped robot. Traditional walking methods require high computational power and advanced controllers to realize bipedal walking. In this proposed method, an exoskeleton attached to the human's lower body is used to obtain the joint information and the obtained joint information is then replicated on a biped robot in real time. The lateral motion of the center of mass of the biped is constrained in this experiment and is not discussed in this paper. Since a direct motion transmission is used in the proposal, this method is quite straight forward and a simultaneous walking can be realized at the same time with a high performance. Also, it doesn't require any dynamic model of the biped or specific trajectory planning method. The gait of the biped is directly determined by that of the human. Therefore, this method can copy the motion of human walking to a biped. Results obtained from the experiments validate the proposed method.

In islanded microgrids, parallel operation of voltage source inverters is commonly enabled by primary droop control to achieve power sharing and secondary control that removes the frequency deviation by mimicking at some extend the operation of an integral controller. Often the main task of the distinct secondary control approaches is to compute a corrective term considering the frequency error that is then used by the droop mechanism for frequency compensation. This paper considers the secondary control approach where local integral controllers that compute the frequency corrective term are implemented at each inverter. And considering that integrals are performed in different nodes, the paper shows that global time between nodes achieved through clock synchronization is mandatory for accurate power sharing and frequency restoration.

This paper investigates the problems of the energy management and power control in a wind generation microgrid at the low wind speed region. A control strategy based on fuzzy-logic control technique is presented that decides for the operational mode of each wind generator and the proper integration to the microgrid. In particular, the developed control algorithm online decides the best-in-case scenario according to the microgrid topology and wind speed conditions for ‘which, when and how long’ each wind turbine of a microgrid should operate at maximum power point tracking (MPPT), remain at stand-still or shut down in order to provide maximum electric energy to the grid and preserve the lifespan of the wind turbines' mechanical and electrical parts. Thus, a multivariable and multi-objective problem is managed for the low wind speed region in order to provide the best in case operational planning of the wind turbines in a microgrid. The common DC-bus topology with permanent magnet synchronous generators (PMSG) has been adopted for the microgrid of this paper; however, it can be applied to any type of microgrid topology and electrical generators. Selective simulation results are presented in order to demonstrate the satisfactory performance of the developed control system.

The work presented in this paper focuses on the transformer modelling, design and parasitic capacitances' effect on transformer operation for three-limb high frequency transformers designed for three port Dual Active Bridge(DAB) converter, using 1200V and 1700V SiC devices. The effects of parasitic capacitance due to high speed and high frequency switching enabled by SiC Mosfet devices are investigated in this paper for three limb transformer of DAB converter. The focus of the paper is based on design, estimation and measurement of parasitic capacitance and leakage inductance for three limb high frequency transformer. Detailed transformer model analysis has been realized for three port DAB operation with parasitics included. Two different transformer design approaches for 10kW, 50kHz rating have been carried out and comparative results have been analyzed in this paper.

Power MOSFET is one of the most rapidly aging components in power electronic converters, and some study of the health monitoring of power MOSFETs is made in this paper. This paper proposes a threshold voltage-based real-time aging monitoring method for power MOSFETs in Buck converters. Firstly, the origins of degradation in power MOSFETs are analyzed, and the junction temperature is indicated to be the most promising failure precursor for the health monitoring. Then, threshold voltage is chosen as the thermo-sensitive electrical parameter for junction temperature estimation. For Buck converters, a real-time threshold voltage monitoring method is proposed. Taking advantage of the particular structure of Buck converters, the proposed method only needs to capture the gate-ground voltage, which is costless and easy to realize. Finally, the effectiveness of the proposed method is verified by simulation and experimental results.

The electric vehicle technology has been adopting PEM fuel cells for hybrid applications over the past decades. Fuel cell systems are often low voltage systems. The key requirements of a boost converter for such application are need of high-voltage. The second-order low-pass filter is often used to filter the high frequency current ripple. It is known that the interaction between the poorly damped filter with the converter leads to degradation of dynamic performance and instability of the system. This paper addresses a novel wide stability control strategy to solve this problem without increasing the weight and size. In this paper, the mathematical model of the system is built. The dynamic stability of the system is investigated based on root locus and Lyapunov first method. The simulation results are reported to verify the effectiveness of the proposed method.

The first dual multilevel converter (MLC) topology for medium-voltage (MV) open-end stator winding induction motor (OESW-IM) drives was proposed in 1990s. Till now, MLC topologies to generate three-level, five-level, seven-level, and nine-level voltage waveforms for OESW-IM drives have been proposed. This paper proposes a new topology for OESW-IM drives based on modular multilevel converter (MMC) topology. The control requirements of the proposed topology are as follows: balancing floating capacitor voltages, removal of common-mode current components in stator current, and low-switching frequency operation with nearly sinusoidal machine stator currents. In this paper, synchronous optimal pulsewidth modulation (SOP) has been improved to satisfy the control requirements of the proposed topology. The proposed method has been validated using a low power experimental setup of dual three-level MMC.

This paper presents an integrated disturbance observer based control and inferential control of a binary distillation column. Disturbance observers have been shown being capable of providing excellent disturbance attenuation. Research into the application of inferential control methods in distillation columns have achieved a much higher quality of control in comparison to the feedback control using composition analyzers which possess substantial measurement delays. This paper takes the novel approach of integrating two frequency domain disturbance observers with multiple tray temperature based inferential estimations of top and bottom product compositions. In order to cope with colinearities in tray temperature measurements, principal component regression (PCR) and partial least square (PLS) regression are used in the soft sensor development. The number of principal components in the PCR model and the number of latent variables in the PLS model are determined using cross validation. The frequency domain disturbance observers have been designed by optimizing the value of the filter time constants within a first order filter, in order to maximize disturbance rejection. The proposed control approach is applied to a binary distillation column for separating methanol and water mixture.

In this paper, the influence of economic variables on the annual electricity consumption in Beijing in 2000–2013 has been investigated. The purpose is to find out their relationship with single data sets and multivariate statistic methods. The multivariate methods used in this paper include ordinary least squares regression (OLSR), principal component regression (PCR), partial least squares regression (PLSR), and modified partial least squares regression (MPLSR). In comparison of these methods, the PLSR model is shown to perform better than the others. The effectiveness of the electricity consumption prediction models is illustrated and verified based on the practical data sets of electricity consumption in Beijing.

With the increase in aging population of many developed countries, the demand of walking or standing up assist device has grown. This paper presents structure and control system of novel assist device, Intelligent Tension Pole (ITP), to assist walking and standing up in room considered supporting for self-reliance, space saving, and stability. Two-wheel and one-wheel are added to lower and upper ends of tension pole collectively, and ball screw is added to move while stretching to floor and ceiling under various conditions. In addition, cooperation control of ITP with human based Ineatial Measurement Unit (IMU) to assist walking is introduced in this paper. Experiments are done to verify the effectiveness of proposed control system.

The paper discusses the problem of speed and load torque estimation for the induction motor drive. Estimation is done considering that the motor fluxes in the stationary frame are available - these have been obtained using a Voltage Model Observer. With known fluxes, the paper designs a sliding mode observer that estimates both the speed and load torque. The observer is designed using an extended model of the motor. The method uses a different approach and is a significant improvement over the classic Model Reference Adaptive System (MRAS) method (which only estimates the speed). Simulations show that, owing to the sliding mode high-gain feedback, the speed estimate is robust and accurate both at steady-state and during transient; the estimate of the load torque is also accurate.

This paper describes the power smoothing control of a hybrid system. The hybrid system is composed of a Battery Energy Storage System (BESS) and a Photovoltaic (PV) generator connected to the grid. The control allows to limit the ramp of the power fluctuations defined by system limits or standard specifications. The different tests shown in the paper demonstrate the relationship between the battery usage and the magnitude of the smoothing. A description of the main parameters for the smoothing control configuration is included. The study case describes the response of a smoothing control on real photovoltaic power fluctuations caused by a one-day clouds passing.

Battery mathematical models can be employed to predict its behavior under various charging and discharging conditions, and in some applications, they are key elements for the successes of the design. In this paper, it is analyzed a lead-acid battery model for voltage and lifetime estimation. The chosen model synthesis is based on an electrical equivalent circuit, and has the features that allow it to be used in the calculation of the remaining capacity. The lifetime model employs an adaptive update mechanism during the simulation such that the battery performance is reduced depending on the operating conditions. This paper objective is to generalize the analyzed mathematical system to be used in any lead-acid battery. Both the model and the estimation algorithm are evaluated with two batteries with same voltage and nominal capacity. The generalization of equation is made by the addition of three new parameters to minimize an objective function based on the least squares error. The study is based on a specific scenario that makes the battery reached the end of its lifetime. With the addition of new parameters, the RMS error between real capacity and calculated capacity are evaluated.

This paper is focused in the inclusion of open software tools and standard hardware devices into advanced mobility aids. Its urgency is due to the incorporation need of the numerous advances in mobile robotics to the area of the Assistive Technologies, and more specifically in the field of the so called Intelligent Wheelchairs (IW). In this paper we propose a common core for IWs based both on an open robotic platform and an open and a well extended software for robotics (ROS “Robotic Operating System”). Such an IW core has got a distributed architecture whose processing nodes are linked through a CAN standard bus, which connects the low level control functions based on low cost and highly portable Cortex platforms. This paper describes also the autonomous navigation algorithm developed for the Intelligent Wheelchair by using an Extended Kalman Filter. In the chosen approach the absolute position of the IW (a mobile robot) is estimated using sensor fusion which combines data from two of the sensory systems included in the described open platform: the dead-reckoning system and a visual system based on QR landmarks located on the ceiling. Within this context, the paper demonstrates the potential of the platform proposal in relation to the quick and easy incorporation of recent advances in mobile robotics.

In this paper, an accurate method is proposed to detect static eccentricity (SE) in induction motors under unbalanced supply voltages. To accomplish this task, one important problem is dealt with: in stator current spectrum of induction machines, the frequency components characteristic of unbalanced supply voltages are similar to some of the frequency components caused by SE. In this direction, the present paper attempts to give an analytical explanation of the generation mechanism of all frequencies related to the SE in order to distinguish them from frequencies related to unbalanced voltages. The theoretical study and the simulation results have been verified by experimental tests conducted on a 1.1 -kW squirrel cage induction motor.

This paper describes a remote control system with a virtual force feedback in a mobile robot. In the mobile robot, a laser range finder is utilized to recognize environmental information. By using this environmental information and the specification of the mobile robot, the safety velocity area (SVA) is calculated in real-time. On the other hand, an operator generates the velocity commands for the mobile robot in real time. By using the relation between SVA and the velocity commands, the virtual force is generated. If the velocity commands are out of SVA, the operator can feel the virtual force. In the previous research, the virtual force is generated based on the only velocity differences. Therefore, the chattering of virtual force commands may occur. In order to solve this problem, this paper proposes the virtual force generation method with hysteresis. Therefore, the operability of the remote control system is increased. From experimental results, the validity of the proposed method was confirmed.

The paper proposes a Fully Flexible Power Transmission & Distribution System (FPTDS) for the next generation power grid, the FPTDS structure used the brand new flexible electric equipment: Energy-Router, Energy-Switcher and Energy-Hub. And then from the Cyber Physical Systems(CPS), the paper gives a Power-CPS (P-CPS) interconnect reference model, and thereby, focuses on designing the fully flexible next generation equipment for Fully Flexible Power Distribution System (FPDS): Energy-Switcher architecture in detail, and researches the next generation distribution grid patterns with Energy-Switchers, presents the grid patterns for all kinds of practical application scenes, finally simulates the Energy-Switcher AC & DC power supply pattern under computer condition, the simulation results demonstrate the systems are feasible and valid.

Medium voltage direct current (MVDC) distribution networks have been considered for various applications, such as offshore wind farm collector systems, all-electric naval vessels, and aircraft. MVDC circuit breakers are a critical technology to directly manage faults in multi-terminal DC (MTDC) networks. However, DC current breaking is much more challenging than in AC systems because there is no natural zero-crossing of the current waveform to aid fault isolation. This paper reviews existing MVDC circuit breaker technologies and also discusses their advantages and disadvantages. This paper also introduces new topologies that can be applied in MVDC applications. The operation of several hybrid DC circuit breaker topologies with aided commutation is included. The paper illustrates that a hybrid DC circuit breaker with aided commutation can clear a fault within 2–5 msecs with low losses, this shows great potential for future MVDC applications. The implications for the practical design of commercial MVDC circuit breakers are also discussed.

This paper describes a non-isolated matrix based buck-boost converter applicable for the aircraft systems. A matrix based topology is used which converters the three phase low frequency input ac voltages into an intermediate high frequency ac voltage. The high frequency ac voltage is rectified using Current Doubler Rectifier (CDR). The output voltage of the CDR circuit is further stepped-up by using a dc-dc boost converter to obtain the desired output voltage. Both, the conventional three phase buck and the three phase boost converter have limitations over the maximum and minimum voltage gain, respectively. The proposed buck-boost converter overcomes such limitations and provides output dc voltage with reduced current distortion and improved power conversion efficiency. Moreover, the novelty of the paper lies in integrating the output filter inductor of the matrix topology with the input inductor of the boost stage resulting in complete elimination of the intermediate filter capacitor and the input boost inductor. The topology and the principles of the operation of the proposed converter are explained in details. Further, the analysis of the converter is carried out. Moreover, the performance of the proposed converter is compared with the boost-buck and conventional buck-boost power converters. The proposed converter is simulated in MATLAB 2015b and results are presented to validate the performance of the converter.

This paper presents a new active gate control (AGC) approach for improving the switching behavior of insulated gate bipolar transistors (IGBTs). The proposed controller is applied on the gate driver (GD) of IGBT, which is based on Posicast control method. The reduction of stress in transient conditions without harmful effect on the efficiency is the main objective of this research that is accomplished by a simple feed-forward controller. The effectiveness of the proposed gate drive controller is verified by both MATLAB/Simulink and PSIM softwares. Moreover, the new GD is implemented in the experimental setup, and the results are reflected in this paper.

In most mechanical and electrical systems, reliability is paramount. Consumers, users and operators trust that their product will perform properly over its expected lifetime. Electric Vehicles (EVs) and Hybrid-Electric Vehicles (HEVs) are no exception to this statement. One of the most important components to consider when determining the reliability of EVs and HEVs is the electric motor. Within electric motors, many things can cause reduced reliability. This paper will focus on the most important component: the bearings. In this review paper, a general summary of bearing failure methods is provided along with an in-depth analysis of all facets relating to the shaft voltage and bearing current phenomenon with specific discussion relating to EV and HEV motors. Subsequently, this paper will provide a review of several mitigation techniques to render the bearing current failure mode obsolete.

This paper describes current control system of PMSM for seamless drive between PWM mode, overmodulation and Square-wave mode of inverter based on model predictive control (MPC). Whereas typical current vector controller determines the ratio of voltage, our proposed current controller based on MPC selects directly the voltage vector sequence of voltage source inverter by prediction of the current behavior. It can be realized not only widening the drive range but also improvement of transient current response by utilization of aggressive square-wave mode in any operating point by selecting the sequence which has overmoduration and Square-wave mode. In this paper, we discuss implementation of proposed MPC and show the experimental results.

This paper deals with a two stage solar photovoltaic (SPV) fed speed sensorless vector controlled induction motor drive (IMD) for water pumping system which is superior to conventional controlled motor as it is cheaper and reliable. One common practice is to estimate the flux from the terminal voltages and currents. The performance of the drive depends on the accuracy of the flux estimator. Usually the efficiency of the induction motor drive (IMD) is high around the rated load and deteriorates at partial loading. However, the efficiency can be enhanced by operating the motor at optimum flux by controlling the flux component of current. In this paper, a minimization technique is proposed to minimize the total losses to operate the drive at maximum efficiency. A modified perturb and observe (P&O) algorithm is used to track maximum power from SPV array. The smooth starting of the motor is attained by vector control of an induction motor. The system performance is simulated in MATLAB/Simulink environment and the results are compared with the conventional vector controlled IMD.

To improve the efficiency of DC-DC converters, this paper focuses on air-core reactors. First, the author deduces the relation between load loss and no-load loss, which originates from ripple current. Next, the author tests a reactor regarding the increase in temperature by changing the waveforms and frequencies under the same cooling and rms current conditions that enable the separation of the DC and AC losses. The results regarding the increase in temperature are different and demonstrate the existence of AC loss in the air-core reactor. It is determined that the AC loss is the eddy-current loss by a finite element analysis. Finally, this paper calculates no-load loss in the DC-DC converter. The AC loss, which consists of eddy-current loss, accounts for more than 90% of the no-load loss. From the results, this paper refers to the importance of the reduction in ripple current in the reactor.

this paper addresses a single-switch IGBT open-circuit faults diagnosis of a two-level voltage source inverter in an induction motor drive system with the direct torque control (DTC) strategy. The proposed diagnostic algorithm consists in the analysis of a stator flux vector amplitude and its position in a stationary reference frame. In accordance with this method the inverter fault is detected when an abnormal local minimum of the stator flux amplitude is observed. Furthermore, for the fault localization the information about a stator currents polarity is processed. Full robustness against false alarms and high effectiveness of the proposed fault diagnostic method has been proved by experimental tests, whose selected results are presented in this paper.

This paper proposes a STATCOM compensation scheme for suppressing commutation failure (CF) in HVDC. In this scheme, the neutral-point of CHB-STATCOM with star configuration is grounded and thus possesses three advantages. Firstly, it keeps the high economy of CHB-STATCOM with star configuration. Secondly, three phases are independent of each other, which can be considered as three single-phase STATCOMs, leading to a simple and flexible control strategy and overcoming the control problem when CHB-STATCOM with star configuration operations under unbalance grid. Thirdly, it forms zero-sequence current channel by taking the characteristic of HVDC, which is the neutral-point of the AC grid connected by HVDC is directly grounded, thus it can compensate not only harmonics, positive and negative-sequence reactive power, but also zero-sequence reactive power, resulting in excellent compensatory capacity. In this paper, first of all, feasibility of the proposed scheme in HVDC is analyzed in detail. Then, zero-sequence current is calculated in detail under unbalance power grid condition. Finally, simulations based on PSCAD/EMTDC are carried out to illustrate the effectiveness to suppress CF in HVDC.

The paper discusses the problem of estimating the rotor time constant of the induction motor. Estimation is done considering that the stationary frame fluxes are available. The fluxes are obtained using a voltage model observer - the paper assumes that the stator resistance and the magnetizing inductance of the motor are known, therefore, the fluxes are accurate. The inverse of the rotor time constant is estimated with a MRAS-type sliding mode observer that uses the incoming fluxes to construct the feedback terms; it also uses a speed signal at the input. Since the speed may be inaccurate, this affects the estimation process. The paper shows that the error in the estimated rotor time constant can be reduced by operating the induction motor with a low ratio of i d to i q . The estimation method involves only simple mathematics and is not computationally intensive. The theoretical claims of the paper are supported with simulations and experiments.

this paper provides an in-depth analysis of distribution of the electromagnetic forces in separately excited dc and ac squirrel cage induction machines. Investigation of local forces acting on the stator and rotor core and windings will shed light on inherent similarities in the mechanism of force generation in two families of electrical machines. This paper also provides a physically insightful explanation of the impact of armature and field currents (quadrature and direct component of current in induction machine) on radial and tangential components of the magnetic forces.

The operation of an air-conditioning system, completely powered by geothermal energy, with no other external energy input and no heat pump is described in this paper. This geothermal system can contribute to the reduction of electricity consumption in residences and small businesses, and can retrofit any installation, since it is a surface geothermal energy installation. That is possible because soil temperature, to a certain depth, has a constant temperature throughout the year, with a large mass and heat capacity. Practical tests can be easily conducted with water and underground heat exchangers. This system is designed with a coolant circulating within a serpentine driven by a small hydraulic pump. If the temperature inside the residence is lower or higher than the soil temperature, there is heat exchange between the residence ambient and the soil. Therefore, the surface geothermal energy is used to warm-up or cool-down the room ambient. The prototype described in this paper was implemented with an electronic control to maximize the performance of the heat exchangers. Experiments were made during four months in the winter and in the summer.

An interleaved current-fed bidirectional full-bridge DC/DC converter for on-board Electric Vehicle (EV) charger is proposed in this paper. This proposed DC/DC converter interleaves two isolated full-bridge converters. In the forward direction power flow, it is an input-parallel output-series (IPOS) voltage-fed construct with the merits that low input current ripple and output voltage ripple. The IPOS construct can also decrease the current stress on the primary side devices and voltage stress on second side devices. In the reverse direction power flow, it is an input-series output-parallel (ISOP) current-fed construct with the merits low input voltage stress and low output current stress. It can realize zero current switching (ZCS) by second-side voltage clamping technique without snubber circuit. Moreover, the boost topology can decrease the turn ration of the transformer and lower the input current ripple. These merits make the bidirectional converter suitable for electric vehicles charging and driving mode. Operation equivalent circuits, analysis, simulation results are presented in this paper. A 3.3KW on-board EV charger prototype is built to demonstrate the validity of the proposed topology.

This paper studies the cage torsional vibrations in a traction drive comprising a variable-frequency voltage-source inverter and a fabricated-cage induction motor. End-ring vibrations may arise due to harmonic torques, with exciting frequencies matching the cage mechanical resonance frequency. It is shown that abnormal cage torsions may lead to bar breakage due to high-cycle fatigue. An actual case-study is presented, with cage vibration measurements. The measurements are matched with dynamic simulations of the complete electro-mechanical system comprising a vibrating-cage motor and the static converter. This paper shows full details of the dynamic model. Modal frequency calculation is also carried out. The model may help to identify the origin of vibrations and the fault root-cause in faulted drives, or may support the designer in preventing harmful cage resonances at the drive design stage.

This paper develops a design methodology aimed to shape passive the admittance of the LCL grid-connected voltage source converters (VSCs). A novel aspect of this work is the assessment of the range of frequencies for control design: due to discrete and PWM operation, the effectiveness of the control action is more and more reduced as frequency increases; in practice, system delays and non-linear effects tend to impair the passivity properties and also its experimental validation. However, as shown in this paper, those effects can be minimised by including the LCL filter as a part of an outer VSC admittance: this assumption is supported by the fact that high frequency disturbances (generated in the point of connection) are absorbed by the LCL capacitor branch, and hence, are not able to create a positive feedback in the VSC (i.e., the active component). By taking advantage of this remark, the inner VSC admittance can be shaped by a reduced order filter in the Z-domain, which mainly depends on the proportional and active damping (controller) gains. The design hypotheses and the control design methodology are verified by PLECS switching-mode simulations.

The paper deals with the operational analysis of resonant DC-DC converter, which is LCLC type. Main circuit of proposed converter consists of one series and one parallel LC branches. The output of the converter is expected to be DC, thus voltage diode rectifier is connected to output stage. At the beginning of the paper the topology of proposed converter is being described, whereby main focus is given for application field and on possibility of its variable use. Next, description of operation intervals is given. Considering DC output and voltage diode rectifier mathematical interpretation of state variables is derived for each operation interval. After it, simulation analysis is provided in order to verify mathematical interpretation of proposed converter.

This paper presents a novel hybrid modulation method based isolated high frequency (HF) bidirectional inverter for AC microgrid application. Bidirectional current-fed converter has been employed to interface the energy storage and intermediate fluctuating dc bus. A new hybrid modulation techniques consisting of fluctuating-dc-modulation (FDM) at low frequency (LF) scale and secondary modulation (SM) at HF scale has been proposed for the current-fed converter. The zero current soft switching (ZCS) of primary side devices and zero voltage soft switching (ZVS) of secondary side devices of front-end current-fed full-bridge converter is realized. The back-end full bridge inverter has been utilized to interface the fluctuating dc bus and AC microgrid. A rotating partial hybrid pulsewidth modulation (RP-HPWM) has been introduced. One leg of inverter is commutated at low switching frequency while the other leg is operated at high switching frequency for partial period of line frequency cycle. Besides the high switching frequency operated switches are only commutated at low value of current flowing through them. Thus, switching losses of the back-end inverter can be considerably reduced. Rotating mechanism is used to equalize the switching losses of four switches of the inverter. The low frequency (LF) fluctuating dc bus allows the reduction of dc-link electrolytic capacitor. This paper presents operation and analysis of the complete inverter topology implementing the proposed hybrid modulation scheme. Simulation results using PSIM9.0.4 and experimental results from a lab prototype clearly validate effectiveness of the proposed modulation scheme.

Grid injecting ac current from grid connected inverters contains harmonic components which can be effectively attenuated by LCL type filters with comparably low filter cost. Recent researches tell that the current harmonics stem not only from high order PWM switching itself but also from low order dead time control for the PWM switching. However, low order current harmonics from the dead time control are not fully investigated yet. This paper shows that the ratio of filter inductances in LCL filters is one of important factors relating with the filter performance. This paper analyses frequency responses of LCL filters to get optimal inductance ratio in grid connected inverters. Simulation results verify proposed optimal inductance ratio for LCL filters to attenuate both high order switching harmonics and low order dead time control harmonics.