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The main aim of this work is to present a step-by-step procedure to model and analyze the power loss distribution of three-level Gallium Nitride (GaN) inverters. It has been applied to three distinct three-phase three-level voltage source inverters utilized in electric traction drives: Active Neutral Point Clamped, Neutral Point Clamped and T-Type Neutral Point Clamped. The proposed analytical power loss modelling, combined with an equivalent representation of the electrical machine proved to be a viable solution to achieve a time-saving and low computational burden simulation platform, leading to satisfying accurate results. This has been confirmed by comparing the results carried out from the simulations of a 110 kW permanent magnet synchronous motor drive and those determined by considering a simplified circuital representation based on the proposed analytical power loss modelling. [ABSTRACT FROM AUTHOR]

The paper presents a self-sensing control technique for a special type of multilevel motor drive featuring an Open-end Winding Permanent-Magnet Synchronous Motor fed on one side by a main multilevel inverter (MLI) and on the other side by an auxiliary two-level inverter (TLI). In order to minimize the power losses, the MLI manages the machine active power operating at a low-switching frequency. The TLI instead acts as an active power filter and operates at a higher switching frequency and a lower DC-Bus voltage than the MLI. The current control task is shared between the two inverters, as a predictive action is exerted by the MLI, while a feedback action is accomplished by the TLI. Common sensorless rotor position estimation techniques cannot be straightforwardly applied on such a system, due to the particular drive structure. Therefore, a specific technique has been carried out, able to ensure satisfactory efficiency and control performance in all the operating speed ranges by optimally exploiting the different features of the two inverters. Simulation and experimental results confirm the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

A technique to improve the performance of grid-connected induction motors by exploiting an auxiliary winding set is proposed in this paper. This auxiliary winding features the same distribution of the main winding, although with a reduced number of turns and it is fed by an inverter a fraction of the power in comparison with the rated size of the induction motor. As shown in the paper, through the auxiliary winding, it is possible to set the machine power factor, increasing the efficiency of the power conversion system and mitigating speed oscillations due to torque disturbances. A mitigation of the grid current peaks due to motor start-up is obtainable. First, the proposed technique is theoretically introduced, then a feasibility assessment is accomplished by simulations. [ABSTRACT FROM AUTHOR]

A three-phase multi-level multi-input power converter topology is presented for grid-connected applications. It encompasses a three-phase transformer that is operated on the primary side in an open-end winding configuration. Thus, the primary winding is supplied on one side by a three-phase N-level neutral point clamped inverter and, on the other side, by an auxiliary two-level inverter. A key feature of the proposed approach is that the N-level inverter is able to perform independent management of N − 1 input power sources, thus avoiding the need for additional dc/dc power converters in hybrid multi-source systems. Moreover, it can manage an energy storage system connected to the dc-bus of the two-level inverter. The N-level inverter operates at a low switching frequency and can be equipped with very low on-state voltage drop Insulated-Gate Bipolar Transistor (IGBT) devices, while the auxiliary inverter is instead operated at low voltage according to a conventional high-frequency two-level Pulse Width Modulation (PWM) technique and can be equipped with very low on-state resistance Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) devices. Simulations and experimental results confirm the effectiveness of the proposed approach and its good performance in terms of grid current harmonic content and overall efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a procedure to simulate an electronic power converter for control design and optimization purposes is proposed. For the addressed application, the converter uses SiC-MOSFET technology in bidirectional battery chargers composed of two power stages. The first stage consists of a single-phase AC/DC power factor correction synchronous rectifier. The following stage is a DC/DC dual active bridge. The converter has been modulated using a phase-shift technique which is able to manage bidirectional power flows. The development of a model-based simulation approach is essential to simplify the different design phases. Moreover, it is also important for the final validation of the control algorithm. A suitable tool consisting of a system-level simulation environment has been adopted. The tool is based on a block diagram design method accomplished using the Simulink toolbox in MATLAB™. [ABSTRACT FROM AUTHOR]

Distributed power converters represent a technical solution to improve the performance of large or utility-scale photovoltaic (PV) plants. Unfortunately, evaluation of the yield obtained in large PV fields by using distributed converters is a difficult task because of recurring partial unavailability, inaccuracy of power analyzers, operating constraints imposed by the Power Plant Controller and so on. To overcome such issues in real operating scenarios, a new modeling strategy has been introduced and validated in terms of computational complexity and accuracy. This approach is based on the state-space averaging technique which is applied to large PV plants with multiple conversion stages by performing some elaborations in order to get a final integrated model. The new modeling strategy has been tested in MatLab Simulink environment using data coming from a 300 MW PV plant located in Brazil representing the case study of this work. In this plant, one subfield is equipped with central inverters while another is with string inverters. The proposed model, whose accuracy is in the range from 2.2 to 2.7% with respect to the measured energy, effectively supports data analysis leading to a consistent performance assessment for the distributed conversion system. Final results highlight that string inverters ensure a gain of about 2% in terms of produced energy. [ABSTRACT FROM AUTHOR]

A multi-level open-end winding converter topology for multiple-motor drives is presented featuring a main multi-level inverter processing the power delivered to the motors and an active filter based on an auxiliary two-level inverter. The main inverter operates at the fundamental frequency in order to achieve low switching power losses, while the active filter is Pulse Width Modulation (PWM) operated to suitably shape the motor currents. The proposed configuration features less phase current distortion than conventional multi-level inverters operating at the fundamental frequency, while achieving a higher efficiency compared to PWM multi-level inverters. Experimental results confirm the effectiveness of such a configuration on both multiple motors-single converter and multiple motor-multiple converter drives. [ABSTRACT FROM AUTHOR]

The development and the validation of an averaged-value mathematical model of an asymmetrical hybrid multi-level rectifier is presented in this work. Such a rectifier is composed of a three-level T-type unidirectional rectifier and of a two-level inverter connected to an open-end winding electrical machine. The T-type rectifier, which supplies the load, operates at quite a low switching frequency in order to minimize inverter power losses. The two-level inverter is instead driven by a standard sinusoidal pulse width modulation (SPWM) technique to suitably shape the input current. The two-level inverter also plays a key role in actively balancing the voltage across the DC bus capacitors of the T-type rectifier, making unnecessary additional circuits. Such an asymmetrical structure achieves a higher efficiency compared to conventional PWM multilevel rectifiers, even considering extra power losses due to the auxiliary inverter. In spite of its advantageous features, the asymmetrical hybrid multi-level rectifier topology is a quite complex system, which requires suitable mathematical tools for control and optimization purposes. This paper intends to be a step in this direction by deriving an averaged-value mathematical model of the whole system, which is validated through comparison with other modeling approaches and experimental results. The paper is mainly focused on applications in the field of electrical power generation; however, the converter structure can be also exploited in a variety of grid-connected applications by replacing the generator with a transformer featuring an open-end secondary winding arrangement. [ABSTRACT FROM AUTHOR]