Matteo Tomasini

A Hybrid Modular Multilevel Voltage Source Converter for HVDC Power Transmission

HVDC transmission systems are becoming increasingly popular when compared to conventional ac transmission. HVDC voltage source converters (VSCs) can offer advantages over traditional HVDC current source converter topologies, and as such, it is expected that HVDC VSCs will be further exploited with the growth of HVDC transmission. This paper presents a novel modular multilevel converter hybrid VSC intended for the HVDC market. The concept of the converter operation is described based on steady-state ac-dc power balance. Techniques for dynamic voltage control, enabling the active and reactive powers exchanged with the grid to be controlled, are introduced. Simulation results further illustrate the theory of operation of the converter and confirm the viability of the proposed control approaches. Detailed predictions of the semiconductor losses confirm the potential to achieve very high efficiencies with this topology. Experimental results are provided to validate the presented converter operation.

A 72 kVA very fast four-quadrant converter based on hybrid Si-SiC IGBTs

In this paper, the design and experimental results of a prototype of a 72 kVA very fast converter for physics research are presented. Hybrid Si-SiC IGBT power modules and an advanced fast control scheme were used to achieve very small response latency (<;50 μs) and high current control bandwidth (3 kHz).

Active Stator Variable Speed Drive: 120 kW DC-fed demonstrator

Current requirements in multi-megawatts electric marine propulsion systems and wind power generation, particularly in off-shore plants, ask for drives with increased power densities. The recently proposed Active Stator (AS) Variable Speed Drive is a clear answer to this demand. A power density increase of up to 2–3 times is anticipated compared to the current state-of-the-art equivalent drives. Such a major leap forward is primarily achieved through the use of a machine with trapezoidal distribution of the air-gap flux density and through the integration of the machine power electronics into the machine frame, as is suggested by the expression Active Stator. The AS topology is well suited to both AC and DC supply types. This is an important feature when the previously mentioned applications of the AS topology are considered, as both are seemingly open to both types of supply. This paper describes the AS topology and reports the main results obtained from a DC-fed 120 kW demonstrator purposely built to prove the AS topology.

Design and Manufacturing of the SiC-Based Power Supply System for Resistive-Wall-Mode Control in JT-60SA

In JT-60SA, the control of resistive-wall-mode (RWM) instabilities will also be realized with a dedicated active control system based on 18 in-vessel sector coils. Each coil will be fed independently by a dedicated fast inverter. Due to the outstanding dynamic performance required, new insulated-gate bipolar transistor modules based on silicon carbide (SiC) have been adopted. Being capable to switch at 30 kHz, these components, together with a very fast control system, allow reaching the required high dynamic performance with the simple and compact H-bridge topology. The RWM-PS will be the first power supply system for fast control of plasma instabilities in fusion experiments adopting SiC semiconductors. This paper gives an overview of the final design of the RWM-PS, with particular emphasis on its special features and the solutions implemented to satisfy the critical requirements. The issues related with the high switching frequency and the peculiar nature of the load will be treated in detail.