The use of series architecture nowadays is mainly on hybrid buses. In comparison with series-parallel and parallel architectures, which are usually exploited on medium-size cars, the series architecture allows achieving internal combustion engine higher efficiency. The downside of this architecture, due to a double energy conversion (i.e., mechanical energy converted in electrical energy and electrical energy converted again in mechanical energy), is that additional losses are introduced. For this reason, the parallel and the series/parallel architectures were considered more suitable for hybrid medium-size cars. Nevertheless, the use of new technologies can change this scenario. Regarding storage systems, supercapacitors achieved a significant energy density, and they guarantee much higher efficiency than battery storage. Moreover, the use of wide-bandgap components for power electronic converters, such as silicon carbide devices, assure lower losses. In this scenario, the series architecture can become competitive on medium-size cars. This paper shows a review of various studies performed on this topic.

Sensorless control of permanent magnet synchronous motors is nowadays used in many industrial, home and traction applications, as it allows the presence of a position sensor to be avoided with benefits for the cost and reliability of the drive. An estimation of the rotor position is required to perform the field-oriented control (FOC), which is the most common control scheme used for this type of motor. Many algorithms have been developed for this purpose, which use different techniques to derive the rotor angle from the stator voltages and currents. Among them, the so-called passive methods have gained increasing interest as they do not introduce additional losses and current distortion associated instead with algorithms based on the injection of high-frequency signals. The aim of this paper is to present a review of the main passive sensorless methods proposed in the technical literature over the last few years, analyzing their main features and principles of operation. An experimental comparison among the most promising passive sensorless algorithms is then reported, focusing on their performance in the low-speed operating region.

In recent years, part of the efforts of the electric drive researcher has been focused on the study of sensorless control algorithms that allow controlling the machine without a speed measure and with ever-fewer measurement devices. This article proposes a possible solution for the submarine application of an asynchronous motor. The motor is designed to drive a petrol pump at a depth of three thousand meters. The motor is fed by an inverter that is located on an offshore platform, and they are connected through a filter and a cable that is 19.74 km long. In this application, it is not suitable to use a speed measurement device; in fact, at this depth it is important to use as few components as possible, in order to increase the system reliability. A control algorithm that only needs available electrical measures is proposed below.

Asynchronous machines are always widely used in most industrial applications due to their reliability, flexibility, and manoeuvrability. To achieve variable speed operations, the quite simple open-loop V/Hz control is largely utilized. Under open-loop V/Hz control, the nonlinear interaction is well known to cause current and torque oscillations while operating at low to medium speeds under light loads. This article presents the stability analysis of induction motors at low–medium frequencies under no-load conditions with the V/Hz control. A system representation in the form of state space is discussed, and the region of instability is plotted against the V/f plane. Two novel and refined methods for the mitigation of oscillations in the region of instability are presented. The two proposed algorithms are finally tested and validated through simulation on an inverter-fed induction motor drive system.

A medium voltage induction motor drive for a submarine oil pump is considered in this paper. In the considered application, the inverter is located on the oil platform, whereas the submersible oil pump is located under the sea and it is supplied with a 20-km long cable. Moreover, an LC filter is located at the inverter output on the platform. In addition, since all the motor sensors should be maintained with submarine robots, stator voltage, stator current and rotor speed sensors are not installed on the motor for reliability reasons. In this study, a new sensorless control is developed. The proposed control integrates a voltage drop compensation and a stator voltage-current estimation into a sensorless control based on a Luenberger Observer. The effectiveness of the proposed control is proved by experimental tests on a low voltage motor, on a 6.6 kV-710 kW motor and on a 2.1 MW-10.5 kV motor.

This article presents a new control algorithm for matrix converters based on full-state feedback. An H ₂ -linear matrix inequality (LMI) framework has been adopted to expand the system stability region. The proposed approach differs from other stabilization methods proposed in literature by its ability to increase the power transfer through the converter while maintaining high control bandwidth and preserving the quality of input and output quantities. A Kalman filter has been introduced to estimate the full system state avoiding the installation of additional sensors. Furthermore, the method has a limited computational burden not requiring high performance control platform. Experimental tests compare the performance of the proposed strategy with a stabilization approach previously proposed in terms of stability performance and power quality.