To obtain a full exploitation of battery potential in energy storage applications, an accurate modeling of electrochemical batteries is needed. In real terms, an accurate knowledge of state of charge (SOC) and state of health (SOH) of the battery pack is needed to allow a precise design of the control algorithms for energy storage systems (ESSs). Initially, a review of effective methods for SOC and SOH assessment has been performed with the aim to analyze pros and cons of standard methods. Then, as the tradeoff between accuracy and complexity of the model is the major concern, a novel technique for SOC and SOH estimation has been proposed. It is based on the development of a battery circuit model and on a procedure for setting the model parameters. Such a procedure performs a real-time comparison between measured and calculated values of the battery voltage while a PI-based observer is used to provide the SOC and SOH actual values. This ensures a good accuracy in a wide range of operating conditions. Moreover, a simple start-up identification process is required based on battery data-sheet exploitation. Because of the low computational burden of the whole algorithm, it can be easily implemented in low-cost control units. An experimental comparison between SOC and SOH estimation performed by suggested and standard methods is able to confirm the consistency of the proposed approach.

Power generation systems (PGSs) based on hybrid renewable energy are one of the promising solutions for future distributed generation systems. Among different configurations, hybrid photovoltaic-wind turbine (PV-WT) grid connected PGSs are the most adopted for their good performance. However, due to the complexity of the system, the optimal balance between these two energy sources requires particular attention to achieve a good engineering solution. This paper deals with the optimal sizing of PV-WT by adopting different multicriteria decision analysis (MCDA) optimization approaches. Sensitivity of MCDA algorithms has been analyzed, by considering different weighting criteria techniques with different fluctuation scenarios of wind speed and solar radiation profiles, thus highlighting advantages and drawbacks of the proposed optimal sizing approaches. The following study could be assumed as a powerful roadmap for decision makers, analysts, and policy makers.

This paper deals with the analysis and implementation of a new scalar control technique for industrial interior permanent-magnet synchronous motor drives that exploits energy-saving capability. In particular, the proposed control strategy forces the conditions of maximum torque per ampere (MTPA), flux weakening (FW), and maximum torque per voltage (MTPV) simply by assigning polynomial relationships between the operating angles of the machine. Although the dynamic performance of the drive is worsened compared to that of vector control schemes, the modified scalar control allows us to work in energetic conditions, very close to those obtained with vector-controlled drives exploiting MTPA, FW, and MTPV strategies. The control techniques are implemented without using any speed and voltage measurement and with only a single current feedback. This paper provides a detailed study of the control strategy, showing the effectiveness and limitations of the method through simulations and experimental results.

High-resolution position and velocity estimation algorithms based on binary Hall-effect sensors for low-cost vector control drives have been the subject of significant research in recent years. While different estimation algorithms have been proposed and analyzed, no contribution so far has dealt with Hall-effect sensor faults and their repercussion on the drive. Here, single and multiple Hall-effect sensor faults are analyzed, and a method to detect, identify, and mitigate such faults is investigated. The method is general, and it ensures proper operation of the drive and is not dependent on the particular estimation algorithm that is used; by way of example, here it will be applied to a vector-tracking observer. Limitations on the performances of the faulty system are discussed, and experimental results are reported to confirm the theoretical analysis.

In this paper, binary Hall-effect sensor faults are investigated in rectangular-current-fed brushless dc (BLDC) drives and a very effective methodology for their detection, identification, and compensation is explored. It is shown that these faults cause erroneous commutation, generally leading to unstable operation. Using a fault detection and identification technique proposed by the authors in a recent paper on low-cost field-oriented drives, it is possible to pinpoint the faulty sensors. In this paper, it is demonstrated that the destabilizing effect of these faults on motion-state estimation can be compensated for in any position and speed estimation algorithm, as long as it is properly readapted. To this end, it is shown how to incorporate such fault-compensation in three state-of-the-art estimation algorithms: (1) the zeroth-order algorithm (ZOA); (2) the hybrid observer (HO); and (3) the vector-tracking observer (VTO). Comparative experimental tests are performed and it is verified that stable operation is achieved with three, two, or only a single Hall-effect sensor functioning correctly. These results show that the classical BLDC drive with three Hall-effect sensors has an inherent double redundancy to position-sensor faults. With the proposed method, this property can be exploited in systems that require very high reliability, such as in aerospace and automotive applications. Redundancy can be increased, using more than three Hall-effect sensors; reduced using two sensors; or eliminated using a single sensor, in ultra low-cost applications where redundancy is not a requirement.

An open-end winding machine configuration and a suitable control strategy for medium-voltage ac motor drives applications are proposed in this paper in order to reduce the distortion of phase voltages in multilevel inverters (MLIs). Differently than standard open-end winding configurations, where two inverters provide active power to both sides of the stator winding, a main MLI supplies in this case the machine on one side, while an auxiliary two-level inverter acts as active power filter on the other side. A high efficiency step modulation manages the MLI, while the auxiliary unit is pulse width modulation (PWM) operated. As the phase current harmonic content is improved, the torque ripple is reduced and the drive efficiency is increased. By exploiting the proposed approach, the apparent switching frequency of the system is that typical of a PWM inverter, although the main unit is operated according to a voltage step modulation strategy. Simulation and experimental results confirm the consistency of the proposed methodology.