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In this paper, the application of optimal state estimation and optimal state feedback algorithms for real-time active magnetic bearing control is treated. A linear quadratic Gaussian controller, consisting of an extended Kalman filter and an optimal state feedback regulator, is implemented. It is shown that this controller yields improved rotor positioning accuracy, better system dynamics, higher bearing stiffness, and reduced control energy effort compared to the conventionally used proportional–integral–differential control approaches. In addition, a method for compensating unbalance-caused forces and vibrations of the magnetically levitated rotor is presented which is based on the estimation of unknown disturbance forces. All results achieved in this paper are verified by means of measurements. [ABSTRACT FROM PUBLISHER]

Energy management of heating, ventilation, and cooling (HVAC) has become a primary concern for residential and commercial buildings. In order to save energy without compromising the comfort of occupants, various techniques have been explored to sense the real-time occupancy/vacancy of HVAC zones. Among all these approaches, wireless-camera-based sensing stands out for its potential application in surveillance and security in addition to energy management. However, limited lifetime and detection accuracy have prevented pervasiveness of wireless-camera-based occupancy detection. This paper presents a novel wireless device platform and prototype development that incorporates an infrared (IR) camera with an optical (OP) camera to provide collaborative intelligence at low power and enhanced accuracy. Compared to the single-sensor baseline design, the proposed fusion-based OP/IR design demonstrates $5\times$ miss rate improvement, $5\times$ reduction in false positive rate, and $3\times$ lifetime extension for battery usage with respect to a single-sensor-based design. Compared to a programmed thermostat and schedule-based HVAC control, the design saves a maximum of $26\%$ of HVAC energy. [ABSTRACT FROM AUTHOR]

In this paper, a generalized formulation for intelligent energy management of a microgrid is proposed using artificial intelligence techniques jointly with linear-programming-based multiobjective optimization. The proposed multiobjective intelligent energy management aims to minimize the operation cost and the environmental impact of a microgrid, taking into account its preoperational variables as future availability of renewable energies and load demand (LD). An artificial neural network ensemble is developed to predict 24-h-ahead photovoltaic generation and 1-h-ahead wind power generation and LD. The proposed machine learning is characterized by enhanced learning model and generalization capability. The efficiency of the microgrid operation strongly depends on the battery scheduling process, which cannot be achieved through conventional optimization formulation. In this paper, a fuzzy logic expert system is used for battery scheduling. The proposed approach can handle uncertainties regarding to the fuzzy environment of the overall microgrid operation and the uncertainty related to the forecasted parameters. The results show considerable minimization on operation cost and emission level compared to literature microgrid energy management approaches based on opportunity charging and Heuristic Flowchart (HF) battery management. [ABSTRACT FROM PUBLISHER]

Currently, the development of a leading-edge technology for saving and reproducing human motions in terms of haptic information is required for various fields. To address these requirements, a motion-copying system has already been proposed. This system is a key technology that enables the realization of the acquisition, preservation, and reproduction of real-world haptic information. In order to apply this system to various fields, the use of the concept involving two types of coupling is important: that involving spatial and temporal couplings. In this paper, the use of the concept mentioned earlier is proposed, and the related system is named “spatiotemporal coupler.” The proposed coupler is divided into two couplers. One is a spatial coupler, and the other is a temporal coupler. The spatial coupler connects human motions that are saved by haptic devices with different configurations according to the information for a human model. On the other hand, the temporal coupler integrates the saved motions temporally, and the integrated motion is reproduced as a single motion. The proposed concept is applied to finger motion in the experiments. The experimental results validate the proposed technology. [ABSTRACT FROM PUBLISHER]

This paper proposes new practical optimal current control methods for a newly emerging class of synchronous motors with hybrid rotor fields by both permanent magnet and winding. In a practical situation with limited voltage, the extensively used permanent-magnet synchronous motor hardly achieves an ideal performance in an energy-efficient manner due to its constant magnet field, which simultaneously allows both low-speed high-torque and wide speed-range operations. The hybrid-field synchronous motors (HFSMs) are potential candidates that can achieve the ideal performance as practical motors with control- lable hybrid rotor field. HFSMs can dynamically control the rotor flux according to the operation requirements by the low-speed, high-torque, and wide speed-range operations, etc. For the HFSMs, the same torque can be produced by a variety of stator and rotor currents due to the nonlinearity between the torque and the currents. Produced losses and required voltages depend upon the associated currents. Consequently, in the situation that current control systems are well constructed, appropriate determination of a set of stator and rotor current commands plays a key role to achieve the ideal performance in an energy-efficient manner. The proposed methods determine the current commands corresponding to a given torque command such that the total winding copper losses due to the stator and rotor currents can be minimized if the exact currents associated with the torque command exist; the best approximate torque can be produced if no exact associated currents exist, which is, of course, under the circumstance of a voltage limitation. The determined current commands are optimal in the sense of energy efficiency or degree of approximation under voltage limitation. New recursive algorithms searching the optimal current solution in real-time are also given as parts of the methods. The proposed methods are analytical but practical, whose usefulness is verified through experiments. [ABSTRACT FROM AUTHOR]

Dynamic wireless charging of electric vehicles (EVs) aims at increasing EV range and reducing battery size and associated costs. Moreover, it minimizes the need for recharging stops, thus increasing travel comfort. As electrification of transport ultimately targets CO2 emissions reduction, increased utilization of renewable energy sources is likely to provide the means for reaching the decarbonization objectives. Demand-side management (DSM) enables the increased penetration of intermittent power sources by providing techniques that ensure grid stability. While complete frameworks for DSM deployment in static charging have been designed, these approaches must be re-evaluated with focus on the operational requirements for dynamic EV charging. In this paper, a review of DSM methods targeting static charging is made and one particular case of DSM is simulated in a dynamic charging environment in order to reveal critical aspects towards deployment. [ABSTRACT FROM PUBLISHER]

Electric vehicles (EVs) with four individually controlled drivetrains are over-actuated systems, and therefore, the total wheel torque and yaw moment demands can be realized through an infinite number of feasible wheel torque combinations. Hence, an energy-efficient torque distribution among the four drivetrains is crucial for reducing the drivetrain power losses and extending driving range. In this paper, the optimal torque distribution is formulated as the solution of a parametric optimization problem, depending on the vehicle speed. An analytical solution is provided for the case of equal drivetrains, under the experimentally confirmed hypothesis that the drivetrain power losses are strictly monotonically increasing with the torque demand. The easily implementable and computationally fast wheel torque distribution algorithm is validated by simulations and experiments on an EV demonstrator, along driving cycles and cornering maneuvers. The results show considerable energy savings compared to alternative torque distribution strategies. [ABSTRACT FROM PUBLISHER]

The voltage range of a renewable energy source, such as the photovoltaic cell, is influenced by the environment, light, temperature, and so on. The power conditioning system should adapt to the wide input voltage and have buck–boost ability. Based on the structure of the “ac/ac unit,” this paper presents a novel active buck–boost inverter (ABI) topology suitable for wide-range input, which can realize buck–boost conversion in a quasi-single-stage inverter. The ac/ac unit composed of active switches is utilized to perform voltage boost without introducing additional passive elements, which is in favor to the system power density and efficiency. Operational analysis in buck and boost modes are presented, and the modulation strategy applied in the ABI is also developed. Simulation and experimental results are presented to verify the operational principle and its modulation strategy. [ABSTRACT FROM PUBLISHER]

A schedule-based approach, such as time division multiple access, is more efficient than a contention-based approach in terms of energy saving by switching sensors into sleeping mode. However, it does not use the transmission media effectively as each time slot is dedicated to a sensor and therefore cannot be used by others should it be idle. Moreover, a schedule-based approach requires a central node to manage and broadcast the schedule to other members, causing high delay and unscalability. On the other hand, contention-based protocols can be used in a distributed fashion. However, contention-based protocols such as IEEE 802.11 waste a lot of energy in idle listening. In this paper, we propose a hybrid approach between contention- and schedule-based protocols. The preliminary results using simulation and a test bed show that our proposed approach uses transmission media more efficiently, leading to lower delay while preserving energy for wireless sensor networks. [ABSTRACT FROM PUBLISHER]

Reducing energy consumption is very important in solving the problem of energy crisis and environmental problem. Usually, an elevator with a diode rectifier wastes regenerated power from its electric motor as heat on breaking resistors. This paper proposes an energy feedback digital system used in an elevator of 18.5 kW which is capable of recycling the regenerated power: obtaining near-unity power factor, sinusoid output current, and low total harmonic distortion in generator-operation state. It has reliable protection circuits and cute man–machine interface, and the feedback point of the dc voltage can be set arbitrarily in a certain extent, meeting the large-range variation of power system voltage. Field operation results showed good performance and energy-saving effect. [ABSTRACT FROM AUTHOR]

This paper extends the single-phase self-driven synchronous rectification (SDSR) technique to multiphase ac–dc systems. Power MOSFETs with either voltage- or current-sensing self-driven gate drives are used to replace the diodes in the rectifier circuits. The generalized methodology allows multiphase SDSRs to be designed to replace the multiphase diode rectifiers. Unlike the traditional SR that is designed for high-frequency power converters, the SDSR proposed here can be a direct replacement of the power diode bridges for both low- and high-frequency operations. The SDSR utilizes its output dc voltage to supply power to its control circuit. No start-up control is needed because the body diodes of the power MOSFETs provide the diode rectifier for the initial start-up stage. The generalized method is demonstrated in 2-kW one-phase and three-phase SDSRs for inductive, capacitive, and resistive loads. Power loss reduction in the range of 50%–69% has been achieved for the resistive load. [ABSTRACT FROM PUBLISHER]

Power electronics technology has gone through dynamic evolution in the last four decades. Recently, its applications are fast expanding in industrial, commercial, residential, transportation, utility, aerospace, and military environments primarily due to reduction of cost, size, and improvement of performance. In the global industrial automation, energy conservation, and environmental pollution control trends of the 21st century, the widespread impact of power electronics is inevitable. It appears that the role of power electronics on our society in the future will tend to be as important and versatile as that of information technology today. In this paper, the importance of power electronics will be discussed after a brief historial introduction in the beginning. Then, the recent advances of power semiconductor devices, converters, variable-frequency ac drives, and advanced control and estimation techniques will be reviewed briefly. Unlike a traditional technology survey paper, the number of figures is kept intentionally small in favor of the text within the length constraint of this paper. The prognosis of different areas will be highlighted wherever possible based on the author's own knowledge and experience. In conclusion and future scenario, the trend of power electronics and motor drives along with some possible research and development areas will be highlighted. [ABSTRACT FROM AUTHOR]

In contrast to hybrid electric cars (HECs), the issues concerning cost, volume, and reliability are even more rigorous when developing hybrid electric scooters (HESs). Therefore, the drive topology and control strategy used in HEC cannot be applied to HES directly. This paper presents a single-stage bidirectional dclac converter based on a general full-bridge inverter. The converter is designed for a low-voltage brushless dc motor/alternator (BLDCM/A) used in HESs, in which the additional bulky inductor and power switches are eliminated in the proposed design. In order to increase the reliability of the commutation process, a cost-effective sensorless control scheme for the motor and alternator commutation is developed. The commutation signals are extracted directly from the average terminal voltages, in which the motor neutral voltage, multistage analog filters, analog-to-digital converters, and the complex digital phase-shift (delay) circuits are eliminated. In addition, instead of using the complex flux-weakening control technique, the winding-changeover technique is exploited to extend the range of the operating speed. With attractive features, such as low cost and ease of implementation, the proposed approach is particularly suitable for electric bikes, electric scooters, HESs, etc. Theoretical analysis and several experiments are conducted to justify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A multisectional power driver design for the two-phase linear brushless motor will be proposed in this paper. The field-oriented modeling of the axial-flux linear brushless motor (AFLBM) will also be developed by using stationary and cosecant similarity transformation and singular value decomposition. Stationary and cosecant coordinate models will be derived based on the proposed approach. Decoupled relation and constant torque property will be obtained from the proposed models. Switching logic table for the linear motor operation is provided to drive the AFLBM properly. The switching-mode analysis for the power driver is also analyzed in detail. In order to increase the efficiency and the effectiveness of the electric motor applications, a multisectional driver circuit, which features the power driver with the so-called N + 2 structure, will be investigated and compared. Experimental results show that the proposed circuit design can achieve better performance with the higher efficiency. It is believed that the proposed driver circuit technique and system modeling can be very helpful to the control of railway transportations. [ABSTRACT FROM AUTHOR]

This paper presents a fuzzy-logic approach to the energy management of an embedded fuel-cell system. The main objective is to study one of the most technological bolts to be overcome for embedded fuel-cell systems: Their energy optimization. To reach this aim, experimentally validated models of a low-power 5-kW proton-exchange-membrane fuel cell and its most power- hungry ancillary (the fuel-cell air-supply system) are described. All simulation results have been performed using Matlab/Simulink environment. Two fuzzy controllers will be proposed for both the internal air-supply control loop and for the whole-embedded energy-management strategy. [ABSTRACT FROM AUTHOR]

Since the system behaviors of a dual-axis inverted-pendulum mechanism including actuator dynamics are highly nonlinear, it is difficult to design a suitable control system that realizes real-time stabilization and accurate tracking control at all times. In this paper, an adaptive sliding-mode control system is implemented to control a dual-axis inverted-pendulum mechanism that is driven by permanent magnet synchronous motors. First, the energy conservation principle is adopted to build a mathematical model of the motor-mechanism-coupled system. Moreover, an adaptive sliding-mode control system is developed for stabilizing and tracking control of the dual-axis inverted-pendulum system, where an adaptive algorithm is investigated to relax the requirement of the bound of lumped uncertainty in the traditional sliding-mode control. In addition, numerical simulation and experimental results show that the proposed control scheme provides high-performance dynamic characteristics and is robust with regard to parametric variations, various reference trajectories, and different initial states. [ABSTRACT FROM AUTHOR]

The large amount of energy consumed in machining by feed-drive systems has become an important issue in recent years because machine tools are extensively used worldwide. This paper presents a novel sliding-mode controller with a nonlinear sliding surface (NLSS) to improve the machining accuracy of ball-screw feed-drive systems. Unlike the conventional sliding-mode control design, the proposed NLSS varies according to the output (controlled variable) so that the damping ratio of the system changes from its initial low value to its final high value as the output changes from its initial value to the reference point. Hence, the proposed algorithm allows a closed-loop system to simultaneously achieve low overshoot and a small settling time, resulting in a smaller error. Experiments to verify the effectiveness of the proposed approach are carried out for a ball-screw feed-drive system for two perspectives. The first perspective is to show the effectiveness of the proposed NLSS in reducing the tracking error, while the second one is to verify the ability of the proposed approach to reduce the consumed energy and control input variation. For the first case, sliding-mode controllers with and without the nonlinear term are compared under the same parameters. The mean of the tracking error magnitude was reduced by 35% without additional electrical energy or control input variation in the controller with NLSS. In the second case, the linear gain is increased for the controller with the linear surface to obtain similar tracking performance. By using the controller with an NLSS, the consumed energy and control input variation were reduced by about 12.9% and 19.1%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents operational characteristics of a small induction motor with the stator core made of amorphous laminations, supplied from mains or a frequency inverter at 50, 100, and 200 Hz. Calculations were performed using field-circuit and equivalent circuit approaches, taking account of nonlinearity and additional losses, both in the core and in the windings. Data for mechanical losses, magnetization curves, and magnetic losses of the amorphous material were experimentally obtained; magnetic measurements were taken as a function of magnetic flux density in the frequency range up to 2000 Hz. Calculated results are compared with measurements. [ABSTRACT FROM AUTHOR]

Residential energy consumption accounts for 21% of the total electricity use in the United States. Unfortunately, research indicates that almost 41% of this power is wasted. Changing the way that consumers use energy may be important in reducing home energy consumption. This paper looks at whether the implementation of certain real-time energy monitors has an impact on the residential rate of energy consumption in a metropolitan area with relatively low electricity rates. In the following case study, 151 Omaha residences were equipped with two variants of the Aztech In-Home Display (Aztech) as well as the Blue Line Power Cost Monitor (PCM) real-time energy monitors for a period of 16 months. The results of the data, 30 days after installation, revealed a statistically insignificant reduction of 12% in mean electrical consumption in houses equipped with a PCM and no reduction in mean consumption in homes using either variants of the Aztech device when compared to a randomly selected control sample. However, they proved effective in the short term if utilized by utilities for mass distribution to foster awareness among participating residents of their own patterns of residential electricity consumption and on the environmental impacts of energy saving. [ABSTRACT FROM AUTHOR]

Information systems are composed of various types of computers interconnected in networks. In addition, information systems are being shifted from the traditional client–server model to the peer-to-peer (P2P) model. P2P systems are scalable and fully distributed without any centralized coordinator. Here, it is getting more significant to discuss how to reduce the total electric power consumption of computers in addition to developing distributed algorithms to minimize the computation time and memory space. In this paper, we do not discuss microlevel models like the hardware specifications of computers like low-energy CPUs. We rather discuss a macrolevel model to show the relation of the amount of computation and the total power consumption of multiple peer computers to perform Web types of application processes. We also discuss algorithms for allocating a process to a computer so that the deadline constraint is satisfied and the total power consumption is reduced. [ABSTRACT FROM AUTHOR]

With ever-increasing concerns on energy issues, the development of renewable energy sources is becoming more and more attractive. This paper first reviews both the wind power and photovoltaic (PV) power generation techniques and their maximum-power-point tracking (MPPT) methods. Then, a new stand-alone wind-PV hybrid generation system is proposed for application to remote and isolated areas. For the wind power generation branch, a new doubly excited permanent-magnet brushless machine is used to capture the maximum wind power by using online flux control. For the PV power generation branch, a single-ended primary inductance converter is adopted to harness the maximum solar power by tuning the duty cycle. The experimental results confirm that the proposed hybrid generation system can provide high efficiency with the use of MPPT. [ABSTRACT FROM AUTHOR]

Diesel generators in small electricity grids are mostly not used in a very efficient way. The reason for this is twofold. First of all, the efficiency of a diesel generator is dependent on the ratio determined by the average power divided by the peak power of the generator. The smaller this ratio is, the lower the efficiency. Furthermore, some loads can regenerate energy. In small grids, this energy is mostly not needed elsewhere and should be dissipated. A solution solving both problems previously mentioned is using an energy storage device in the system. This storage can be used for peak shaving and storing regenerated energy. This paper focuses on a generator-set with energy storage. Six different power management strategies are discussed. Calculation of the costs shows that adding an energy storage device lowers the cost for all methods. Verification with simulation and experiments has been carried out. [ABSTRACT FROM AUTHOR]

Frequent variation of single-phase loads on power system networks results in voltage fluctuations and imbalance at consumer terminals. The application of such fluctuating voltages to operate centrifugal loads causes large variations in system performance. As a consequence, the incorporation of large safety factors have resulted in efficiency of pumping operations being less than 50% in most cases. However, small improvements in pump efficiency can lead to a significant reduction in energy consumption, and at the same time energy usage can be optimized. The operating point of a pump is obtained when the system curve intersects the pump curve. Variation in applied voltages leads to variation in the operating point, leading to inefficiency of system operation. This paper presents the impact of voltage variation and imbalance on the working performance of an induction motor-driven centrifugal pump system with an experimental study. Both overvoltage and undervoltage conditions along with phase imbalance were considered for analysis. [ABSTRACT FROM AUTHOR]

The article informs that recent advancements in design, control and diagnostics in electromechanical-energy converters have motivated this special section on electric machinery and adjustable-speed motor drives-part I of the periodical "IEEE Transactions on Industrial Electronics." It is stated that efficiency in generation and consumption of electricity is a factor by which the future energy challenges will be affected. Due to this factor, as also stated, significance of research and development pertaining to conversion of electromechanical-energy continues to attract substantial attention from academia, industry and governments around the world.

A very efficient energy-management system for hybrid electric vehicles (HEVs), using neural networks (NNs), was developed and tested. The system minimizes the energy requirement of the vehicle and can work with different primary power sources like fuel cells, microturbines, zinc-air batteries, or other power supplies with a poor ability to recover energy from a regenerative braking, or with a scarce power capacity for a fast acceleration. The experimental HEV uses lead-acid batteries, an ultracapacitor (UCAP) bank, and a brushless dc motor with nominal power of 32 kW, and a peak power of 53 kW. The digital signal processor (DSP) control system measures and stores the following parameters: primary-source voltage, car speed, instantaneous currents in both terminals (primary source and UCAP), and actual voltage of the UCAP. When UCAPs were installed on the vehicle, the increase in range was around 5.3% in city tests. However, when optimal control with NN was used, this figure increased to 8.9%. The car used for this experiment is a Chevrolet light utility vehicle (LUV) truck, similar in shape and size to Chevrolet S-10, which was converted to an electric vehicle (EV) at the Universidad Católica de Chile. Numerous experimental tests under different conditions are compared and discussed. [ABSTRACT FROM AUTHOR]

A wind-generator (WG) maximum-power-point-tracking (MPPT) system is presented, consisting of a high-efficiency buck-type dc/dc converter and a microcontroller-based control unit running the MPPT function. The advantages of the proposed MPPT method are that no knowledge of the WG optimal power characteristic or measurement of the wind speed is required and the WG operates at a variable speed. Thus, the system features higher reliability, lower complexity and cost, and less mechanical stress of the WG. Experimental results of the proposed system indicate near- optimal WG output power, increased by 11%-50% compared to a WG directly connected via a rectifier to the battery bank. Thus, better exploitation of the available wind energy is achieved, especially under low wind speeds. [ABSTRACT FROM AUTHOR]

Analyzes the application of speed control strategy for centrifugal pump and fan drives with squirrel-cage induction motors. Theoretical basis of the strategy; Information on Pontriagn's maximum principle; Details on the energy-saving concept of short-time transients.