PARALLEL-CONNECTED MULTI-DRIVE SYSTEMS WITH REDUCED NUMBER OF INVERTER LEGS AND INDEPENDENT VECTOR CONTROL

Completed

Energy Efficiency(Other)
Other Power and Storage Technologies(Electricity transmission and distribution)
Energy Efficiency(Industry)

Basic and strategic applied research

ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering)

Not Cross-cutting

Professor E Levi
Engineering
Liverpool John Moores University

Standard

EPSRC

01 December 2005

30 November 2007

24 months

£209,635

Electrical engineering

North West

Systems -- Materials, Mechanical and Medical Eng

Professor E Levi, Engineering, Liverpool John Moores University

Project Contact, Manchester Metropolitan University
Project Contact, Moog Italiana S.r.l., Italy
Project Contact, Liverpool John Moores University
Project Contact, Semikron Ltd
Project Contact, Verteco Ltd

Numerous industrial applications require two or more variable-speed electric drives, which have to be controlled independently. The existing solution for such applications consists of a set of three-phase motors, which are all supplied from individual three-phase voltage-source inverters and the inverters are customarily paralleled to the common dc link. A fundamentally different concept for a multi-drive system, based on utilisation of multi-phase machines (with a phase number greater than three), is currently in the final year of investigation in an EPSRC project. The concept requires an appropriate series connection of stator windings of a certain number of multi-phase machines and the supply comes from a single multi-phase inverter. Vector control principles are applied to achieve decoupling of the dynamics of different machines in the group. The concept has already been demonstrated to be feasible both theoretically and experimentally and its main benefit, when compared to the standard solution with three-phase machines, is a saving in the required number of inverter legs.This proposal is conceived as a logical successor of the current EPSRC project. It intends to explore the possibility of achieving a saving in the number of required inverter legs using a set of motors paralleled to a multi-phase inverter. This eliminates a drawback of the series connection related to the need to have both beginnings and endings of each stator phase brought out to the terminal box. The project is organised along two research tracks, depending on the number of phases of the motors used. The first track investigates use of paralleled multi-phase machines, supplied from a multi-phase inverter, while the second track looks at utilisation of paralleled three-phase machines, supplied from a multi-leg inverter (with a common inverter leg for the third phase of all machines). Both configurations enable saving of the same number of inverter legs for the given number of machines. It should be noted that both multi-drive configurations are believed to offer a potential for a substantial saving in the required installed inverter power in winder applications.The intention is to develop at first theoretically these two novel concepts and to examine next the characteristics by simulation. Vector control principles will be used and it will be necessary to develop appropriate methods for multi-phase (multi-leg) inverter PWM control in order to apply current control in the rotating reference frame (the emphasis will be on space vector modulation). Experimental part of the project will aim at proving the existence of decoupled dynamic control in these two configurations and will rely heavily on the experimental rig designed and commissioned as a part of the work on the current project. The final part of the research will conduct a comparative analysis of the advantages and shortcoming of the two proposed paralleled multi-drive systems using the standard three-phase multi-drive system, with inverters paralleled to the dc link, as a benchmark. The comparison will include the series-connected multi-phase multi-drive systems as well, thus enabling establishment of guidelines for future use of multi-drive systems

23/03/12