Università degli studi di Modena e Reggio Emilia

When compared to the much more common voltage-source inverter (VSI), the current-source inverter (CSI) is rarely used for variable speed drive applications, due to its disadvantages: the need of a constant DC-link current, typically realized with a front-end converter, and the need for reverse-voltage blocking (RVB) devices, typically implemented with in-series diodes. This limits the overall efficiency of the architecture. This paper investigates latest progress of the CSI research, with the aim of demonstrating why CSI could come back in the near future. Different architectures based on modern wide-bandgap (WBG) switches are analyzed, with an emphasis on why CSI can be advantageous compared to VSI.

In motor drive applications, single-stage current source inverters (CSIs) can manage only a limited speed range when the output voltage is greater than input voltage, due to the intrinsic boost capability. The classical solution adopted in low-speed region to control the input dc current, consists in the insertion of a prestage power converter. This article proposes a single-stage CSI that replaces the input inductance Ldc with coupled inductor. In this way, it is possible to add the needed time interval for the discharge of the magnetic energy of primary inductance Lm when the converter works in low-speed region or at standstill, extending the operating region of the converter. This solution allows to increase the efficiency of traditional CSIs for applications when the motor works most of the time in the high-speed region, thanks to the single-stage power conversion. Experimental and simulation results driving a permanent magnet synchronous machine are shown, confirming the validity of the proposed architecture.

Multi-phase electric drives can be employed in a great variety of applications. Their advantage in terms of fault-tolerance capability is becoming the focus of the work of many research activities, especially in the field of transportation electrification. The main topic is to create redundant and modular multi-three-phase drives to increase the overall system reliability and fault-tolerance. To this aim, distributed control architectures have been assessed. In this paper, a centralized master-slave control is compared against a distributed droop control architecture, in order to identify advantages and drawbacks. Both of the control strategies are applied to a double three-phase drive. The aim of the work is to assess whether the droop control architecture can be a valid alternative to a centralized master-slave control in terms of performances, but with the additional benefit of having a proper full redundant fault-tolerant application.