With the requirements for reducing emissions and improving fuel economy, automotive companies are developing electric, hybrid electric, and plug-in hybrid electric vehicles. Power electronics is an enabling technology for the development of these environmentally friendlier vehicles and implementing the advanced electrical architectures to meet the demands for increased electric loads. In this paper, a brief review of the current trends and future vehicle strategies and the function of power electronic subsystems are described. The requirements of power electronic components and electric motor drives for the successful development of these vehicles are also presented.

Power Electronics and Motor Drives in Electric, Hybrid Electric, and Plug-In Hybrid Electric Vehicles

This paper presents a review of recently used direct torque and flux control (DTC) techniques for voltage inverter-fed induction and permanent-magnet synchronous motors. A variety of techniques, different in concept, are described as follows: switching-table-based hysteresis DTC, direct self control, constant-switching-frequency DTC with space-vector modulation (DTC-SVM). Also, trends in the DTC-SVM techniques based on neuro-fuzzy logic controllers are presented. Some oscillograms that illustrate properties of the presented techniques are shown.

Direct torque control of PWM inverter-fed AC motors - a survey

Field-oriented control and direct torque control are becoming the industrial standards for induction motors torque control. This paper is aimed at giving a contribution for a detailed comparison between the two control techniques, emphasizing advantages and disadvantages. The performance of the two control schemes is evaluated in terms of torque and current ripple, and transient response to step variations of the torque command. The analysis has been carried out on the basis of the results obtained by numerical simulations, where secondary effects introduced by hardware implementation are not present.

FOC and DTC: two viable schemes for induction motors torque control

This paper presents a new direct power control (DPC) strategy for a doubly fed induction generator (DFIG)-based wind energy generation system. The strategy is based on the direct control of stator active and reactive power by selecting appropriate voltage vectors on the rotor side. It is found that the initial rotor flux has no impact on the changes of the stator active and reactive power. The proposed method only utilizes the estimated stator flux so as to remove the difficulties associated with rotor flux estimation. The principles of this method are described in detail in this paper. The only machine parameter required by the proposed DPC method is the stator resistance whose impact on the system performance is found to be negligible. Simulation results on a 2 MW DFIG system are provided to demonstrate the effectiveness and robustness of the proposed control strategy during variations of active and reactive power, rotor speed, machine parameters, and converter dc link voltage

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Direct active and reactive power control of DFIG for wind energy generation

Medium-voltage (MV) induction motors are widely used in the industry and are essential to industrial processes. The breakdown of these MV motors not only leads to high repair expenses but also causes extraordinary financial losses due to unexpected downtime. To provide reliable condition monitoring and protection for MV motors, this paper presents a comprehensive survey of the existing condition monitoring and protection methods in the following five areas: thermal protection and temperature estimation, stator insulation monitoring and fault detection, bearing fault detection, broken rotor bar/end-ring detection, and air gap eccentricity detection. For each category, the related features of MV motors are discussed; the effectiveness of the existing methods are discussed in terms of their robustness, accuracy, and implementation complexity. Recommendations for the future research in these areas are also presented.

A Survey of Condition Monitoring and Protection Methods for Medium-Voltage Induction Motors

The European Commission is supporting many projects to reach the European targets in energy savings and diffusion of renewable resources. The BECA — Balanced European Conservation Approach — ICT Service for Resources Saving in Social Housing, is a project in the frame of 7th ICT-PSP program that involves seven different cities in Europe. The target of the project is to build, and spread among the final users, ICT based services that can improve the energy use awareness of people, without a specific education in the use of energy. Some ICT based services: web services and sms services have been developed and applied in three different sites in Torino (Italy), taking into account the peculiarities of each site. In order to modify the behavior of the final users about energy, an ICT service that allows the comparison of energy consumption (actual consumptions vs past consumptions and consumptions vs middle user's consumptions), has been developed. The ICT service has been made available to the final users and operators in the managing staff.

Smart energy users in social housing by BECA ICT service

Several programs for energy savings are running in the world and most of them are related to the civil and small business environment. The results of energy saving programs depend on technical improvements but are also heavily affected by final users behaviors. The best way to obtain durable energy saving is involving the final users in the program in order to change their habits. Energy consumptions in an assigned environment are affected by several constrains (i. e. weather condition and social habits), in order to evaluate the savings related to a specific program, the energy saving, due to the program only, have to be identified and isolated. Since a large number of factors that can affect the energy consumption, it is difficult to define reliable models that allows the computation or the prediction of energy consumption from the environment input values. In order to evaluate the savings an approach based on the different behaviors of a selected: — experimental group: users that receive all the information related to energy saving program and are involved in the activities of the program itself; — control group: users located in the same environment of the experimental group, but not involved in the in the activities of the energy saving program; is usually adopted. With reference to the EU-IEE program Empowering the procedures for the selection of the experimental and control groups are presented. Some example of additional information to increase the final users' energy awareness is also presented.

Embedding final users in energy saving programs

Modern residential, industrial or commercial buildings may be grounded through a system defined as "TN- Island grounding system". This is an effective way to protect both persons from shock hazard in installations and to greatly limit electrical interferences among power systems. This earthing system, which is aimed to promote electrical safety, better functionality, and lower costs, utilizes single-phase separation transformers installed in the unit grounded at the mid-point of their secondary side. By introducing a new source of power frequency (i.e. extremely low frequency) magnetic fields into the premises, the presence of such additional pieces of equipment in the environment, might expose persons to their potential adverse health effects, as well as, sensitive electronic equipment disturbances. This paper seeks to clarify this matter by evaluating the ELF magnetic fields, as produced by the user's own equipment and by other units eventually present in the vicinity.

Low Voltage Distribution Transformers: Analysis of the Exposure to ELF Magnetic Fields

Convertitore di energia marina

This paper examines the influence of the lamination material and rotor pole geometry on the steady-state performance of a wound field synchronous machine operated in the generating mode. The investigations are carried out through 2D finite element analyses using a commercial software package. Non-Oriented silicon-iron alloys of various grades are selected to recognize the impact of their magnetic properties on the machine performance. Different methods for the extrapolation of BH curves from low-medium field levels to saturation are reviewed and compared. The effect of using different materials on both the rotor and the stator core is assessed in terms of variation of the air gap power, the torque ripple and the core losses. The performance of a new machine featuring a higher-grade lamination material and a refined rotor pole geometry are compared at constant air gap power with those of the reference machine. The results show that, depending on the adopted strategy, it is possible to almost halve the torque ripple and slightly decrease the mass of the rotor core.

Michele Pastorelli

Papers

Smart energy users in social housing by BECA ICT service

Embedding final users in energy saving programs

Low Voltage Distribution Transformers: Analysis of the Exposure to ELF Magnetic Fields

Convertitore di energia marina

Influence of the Lamination Material and Rotor Pole Geometry on the Performance of Wound Field Synchronous Machines