High-frequency signal injection sensorless algorithms are widely studied and used for rotor angle estimation in permanent magnet synchronous motor (PMSM) at low speed or standstill. One of the main drawbacks of such methods is the acoustic noise connected to the voltage injection. In order to minimize this problem, it is advisable to increase the frequency of the injected signal. Thus, many studies focus on square-wave injection at the switching frequency, which is the maximum theoretical frequency. Since these methods exploit the rotor magnetic anisotropy, it is relatively easy to use them in interior PMSMs, where the rotor anisotropy is high. On the contrary, it is hard to exploit them in surface PMSMs, which have an almost symmetric rotor, although a low rotor magnetic anisotropy is still present. In this article, a sensorless algorithm with switching frequency square-wave injection is developed for surface PMSMs. To increase the signal-to-noise ratio, current oversampling is exploited. The benefits of such a technique are demonstrated with experimental results on a 2 N·m SPMSM.

The large-scale spread of hybrid electric vehicles (HEVs) in the automotive industry is dominated today by continuous variable transmission parallel powertrain as far as medium size car are concerned. As a matter of fact, the tendency in this sector is to design parallel architectures in that they have provided until now a higher overall powertrain efficiency. However, technological improvements in many electric components and their increased efficiency can reshape this vision and give new outlines on HEV structure design. This paper aims to show the potentials of the series architecture, thanks to the latest electrical improvements especially in storage systems and power electronics. In particular, simulation models and fuel consumption data over different road missions are presented for the series architecture proposed in this study. In addition, a comparison between these results and data available in the scientific literature for state-of-the-art HEVs is reported.

Sensorless algorithms for PMSM have achieved an increasing interest in the technical literature. They can be divided into active methods and passive methods. Active methods exploit rotor anisotropy by injecting high voltage frequency signals, whereas passive methods are based on observers. Even if passive methods do not have the drawbacks of active methods – acoustic noise, torque ripple and harmonic distortion - their effectiveness is reduced in the low speed region. For this reason, active methods are usually used at low speed and the motor control switches to passive methods in the high-speed region. Since high frequency injection is associated to many drawbacks, the aim of passive methods is to work at lower speed as possible or, ideally, to be able to start directly the motor. That is particularly true for Surface-Mounted PMSM: since they have a low anisotropy, high frequency injection should be particularly elevate to achieve sufficient signal-to-noise ratio. It is difficult to compare the performance of passive algorithms proposed in the technical literature since experimental tests have been done with different conditions: motors, inverter features, measurements, type of tests, etc. In this paper, five different sensorless passive algorithms for Surface-Mounted PMSM, selected among the most promising algorithms available in the technical literature, are compared, performing the same tests on the same experimental setup, to achieve a fair comparison and establishing the most performing one.

In contemporary power electronics, multilevel converters stand at the forefront of high-power, high-voltage applications, offering superior performance in terms of efficiency, reduced harmonics, and improved voltage waveform quality compared to traditional two-level converters. Their capability to synthesize waveforms with multiple voltage levels has garnered significant attention across various industrial sectors, including renewable energy systems, electric vehicles, and high-voltage power transmissions. This paper provides a comprehensive overview of multilevel converter technology, encompassing their classification, main topologies, recent advancements, and emerging trends. By exploring the evolution of multilevel converter technology and identifying future research directions, researchers and engineers can gain valuable insights into the design, optimization, and application of these advanced power electronic systems.

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.

A distorted grid voltage or nonlinear behavior in the current control loop can cause low frequency current harmonics in a grid-connected voltage source inverter (VSI). Many efforts have been made to mitigate such phenomena, including hardware and/or control structure improvements. A well-known suitable strategy to reduce current harmonics in a selective manner is to apply a Proportional Multi-Resonant (PMR) current controller. Inverter-grid stability is another common issue when dealing with grid-connected VSI. Stability is influenced by the inverter impedance, which depends on the controller parameters. This paper presents a simplified tuning strategy for the PMR controller, taking into consideration the inverter-grid stability issue. The obtained controller was implemented and tested in a 10 kW three-phase inverter with a passively damped LCL filter. A significant reduction of current harmonics emission from the inverter up to 650 Hz was achieved without any hardware modification. The limits of PMR controllers to mitigate current harmonics were studied, and the influence of the grid impedance was verified.