Alessandro Galassini

Distributed current control for multi-three phase synchronous machines in fault conditions

Among challenges and requirements of on-going electrification process and future transportation systems there is demand for arrangements with both increased fault tolerance and reliability. Next aerospace, power-train and automotive systems exploiting new technologies are delving for new features and functionalities. Multi-three phase arrangements are one of these novel approaches where future implementation of aforementioned applications will benefit from. This paper presents and analyses distributed current control design for asymmetrical split-phase schemes composed by symmetrical three phase sections with even number of phases. The proposed design within the dq0 reference frame in nominal, open and short circuit condition of one three-phase system is compared with the vector space decomposition technique and further validated by mean of Matlab/Simulink® simulations.

uCube: Control platform for power electronics

This paper presents a versatile tool for development, control and testing of power electronics converters. In the last decade, many different expensive off-the-shelf tools for rapid prototyping and testing have been developed and commercialised by few market players. Recently, the increasing diffusion of low cost, Do It Yourself targeted development tools gained market shares previously controlled by conventional players. This trend has been driven by the fact that, despite their lower performances, many of these low cost systems are powerful enough to develop simple power electronics systems for learning and teaching purposes. This paper describes a control platform developed within the University of Nottingham, targeting at the market and application segment in between the expensive off-the-shelf control boards and the low cost emerging systems. The platform is based on the Microzed evaluation board, equipped with the Xilinx Zynq System-on-Chip. Its flexibility, features and performances will be addressed and examples of how they are being experimentally validated on different rigs will be provided.

State space model of a modular speed-drooped system for high reliability integrated modular motor drives

Future transportation challenges include a considerable reduction in pollutant emissions at a time when significant increase in demand is predicted. One of the enabling solutions is the electrification of transport systems as this should lead to improved operability, fuel savings, emission reduction, and maintenance. While state-of-the-art technology has demonstrable benefits there needs to be considerable advancement to meet future transportation affordability and emission targets. Primarily, electrical drives need an improved power density, an increased reliability, and a reduced specific cost. For this reason, integrated modular motor drives (IMMDs) present an attractive solution. Modularity leads to redundancy and easier integration. This paper presents a novel speed-drooped control system applied to motors fed by modular paralleled converters. This control technique allows precise speed regulation and power sharing among different segments showing improved fault tolerance and reliability. The design procedure and the power sharing dynamic have been presented and analyzed by means of MATLAB/Simulink and validated in a 3-kW experimental rig, showing good agreement with the expected performances.

Speed droop control of integrated modular motor drives

New emission standards are progressively moving transportation systems toward an electrification process that must provide high reliability, fault tolerance and high integration levels. Integrated Modular Motor Drives (IMMD) are an interesting candidate for these applications. Focusing on reliability and fault tolerance, this paper proposes a simple speed droop controller for IMMDs. Extending the concept of droop control to the speed loop of an IMMD, inherent power sharing among the modules and regulated speed are achieved without communication. The paper proposes a simplified design procedure, validated with experimental results from a 3KW rig, showing good agreement with the expected performances.

Speed control for multi-three phase synchronous electrical motors in fault condition

The growth of electrification transportation systems is an opportunity for delving into new feasible solutions for more reliable and fault tolerant arrangements. So far, many investigations distant from the market have been carried out. Most of the works are looking at new control strategies adding extra components increasing manufacturing efforts and costs. Considering a nine phase synchronous multi-three phase electrical motor with disconnected neutral points, this manuscript compares the common speed reference configuration (where all the drives are configured in speed mode) and the torque follower configuration (where one drive is in speed mode and all the others are in torque mode). Furthermore, a post-fault operation in open-circuit condition is proposed. Analytical equations and experimental validation in nominal and fault condition are given by means of Matlab/Simulink simulations and by experimental on a 22kW test rig.

Distributed speed control for multi-three phase electrical motors with improved power sharing capability

This paper proposes a distributed speed control with improved power sharing capability for multi-three phase synchronous machines. This control technique allows the speed to be precisely regulated during power sharing transients among different drives. The proposed regulator is able to control the time constant of the current within the dq0 reference frame to a step input variation. If compared to current set-point step variations, the proposed droop controller minimises devices stress, torque ripple, and thus mechanical vibrations. Furthermore, since distributed, it shows improved fault tolerance and reliability. The design procedure and the power sharing dynamic have been presented and analysed by means of Matlab/Simulink and validated in a 22kW experimental rig, showing good agreement with the expected performances.