Newcastle University

Power Electronics, Drives and Machines Group - Current Activities

The Power Electronics, Drives & Machines Group carries out research into all aspects of Power Electronics and Drive systems including motor design, power semiconductor device applications and circuits, and advanced control strategies. The blend of interests and skills amongst its academic and research staff is unique in UK universities and has been recognised by the large number and wide variety of sponsors for the Group's research work. In terms of both research contract value and publication rate, the Group is the UK's most active in the area of Power Electronics, Drives and Machines.

In 2007 the Group created the Centre for Advanced Electrical Drives, using £1M of funding from One NorthEast. The Centres aims are

• To provide a world leading service to industry for the research and development of advanced electrical drives and machines.
• To assist industry in the creation and maintenance of a market lead in new products containing embedded electrical drives.

The Groups recent activities include:
Novel Electromagnetic Devices: This research is supported by an EPSRC platform grant (EP/F067895), alongside other EPSRC, DTI and industrial funding. Research spans from "blue sky", including new machine topologies and materials, through to application in new areas, working with leading worldwide industries. Highlights include:

• Advances in the development of low costs machines (supported by completed EPSRC Grant GR/S60044), including in particular the development of high speed, very low cost machines for consumer use, work which has been undertaken with many well know industrial partners including Dyson, Black and Decker, Höganäs and Rechi.
• Development of highly efficient electrical machines including notably that used by QinetiQ to power their Zephyr solar powered Unmanned Aerial Vehicle. As a result of this work by Newcastle University and other innovations by the QinetiQ team, this aircraft holds the world record for the duration of an autonomous flight.
• Fault-tolerant permanent-magnet machines: our concepts have found world-wide acceptance, spawning many research and industrial projects. We are the first to demonstrate continued system operation in the event of power device failures or winding short-circuits. Applications include: a 100kW, 30,000 rpm, aircraft main engine fuel pump funded by Goodrich.
• Major advances in switched-reluctance and stepping motors by using segmented rotors and/or the fully-pitched winding structure have increased performance by up to 40%, resulting in an IET award and patents (USPatent 7205694). EPSRC (GR/M07120) judged the work "outstanding".
• Internationally-leading work on the exploitation of insulated, compacted iron-powder for novel and improved performance machines. The world's largest producer of iron-powder (Höganäs of Sweden) has fully funded RAs throughout this RAE period, researching innovative machine design enabled by the 3D nature of iron-powder components. The research has led to a prestige lecture, four keynote addresses and tutorials at International Conferences around the world. The concepts have been explored in projects funded by EPSRC, EU, Bosch, LG, Aesin Seiki, Black & Decker, Burgess Norton, Sumitomo and Electrolux.
• World Class research into the novel Modulated Pole (also know as Transverse Flux) family of machines that promise the potential of very high torque densities. Work has involved the improvement of these machines to reduce costs and increase performance. As such a University of Newcastle designed machine is now to be mass produced by a large Chinese manufacturer.
• Ultra high-speed machines, giving greatly increased power density, e.g. a 100,000 rpm drive for low-cost power tools (doi:10.1049/cp:20060176), in collaboration with Black & Decker, and high-speed vacuum cleaner drives with Dyson. The Black & Decker drive is embedded in a new drill, giving 60% overall weight reduction.

Our research into new methods of manufacture has led to eight International Patents, including several concerned with production innovations.

Power Electronics and Derived Systems: Our research activities are principally directed in the aerospace, automotive and renewable energy generation sectors. Projects are funded by EPSRC, the Technology Strategy Board or directly from industry. Recent key projects include:

• A Novel Generator System for Series Hybrid Electric Vehicles (EPSRC) - The project designs a novel rectifier circuit for SHEV's which overcomes the output voltage drop caused by commutation
• Second Generation 7.5t-12t Diesel/Electric Hybrid Truck (TSB) - The project develops tailored vehicle ancillaries for the truck industry.
• Recent work relating to photovoltaic water pumping, in collaboration with the New and Renewable Energy Centre (NaREC), has led to advances in maximum power point tracking techniques which have increase the energy yield and hence pumping capacity.
• Power Management Systems in Electric and Hybrid Vehicles (TSB) - Design of a low-cost 4 kW/kg dc/dc converter for Hybrid Electric Vehicles.
• Reliability of power modules (EPSRC) - New techniques have been developed to increase the reliability of power-devices, using on-line estimation of the junction temperature. An intelligent controller is used to keep the chip temperature swing low in order to reduce device stresses. In addition a thermal ageing tracker has been implemented to increase the accuracy of the real-time estimator.
• A solution to the long standing problem of DC injection into the grid from photovoltaic power converters. This EPSRC funded work, rated internationally-leading (GR/M16603), also reduced low-order harmonics in multiple grid-connected photovoltaic systems. Carried out in collaboration with TurboPower Systems, Scottish Power and BP Solar.
• Development of a virtual power system using multilevel converters has allowed fast power system transients to be emulated, leading to commercially funded research from Econnect for grid-connected converters for wind and photovoltaic generation.
• The world's first fault-tolerant aerospace drives which intelligently reconfigure in the event of machine or power electronic failures. Demonstrators range from fuel pumps and landing gear steering (Goodrich) to production of a full demonstrator electrical flap and slat actuation system (BAE Systems, FR HiTemp).

Estimation and Control: Research is funded by both EPSRC and industry, producing innovative solutions which are now being adopted for commercial products. Highlights include:

• Speed sensorless control utilising methods such as high frequency injection and wavelets.
• Stability analysis and control of nonlinear dynamical systems like power electronics and/or electrical machines (currently focussed on Switched Reluctance Machines). We have succeeded in creating a supervising controller that greatly extends the stable operation of various power converters and electrical machines. Based on that approach we were able to reduce the size of the inductor in dc-dc converters by almost 50% which means smaller, lighter and cheaper converters.
• Multiple position estimators for fault-tolerant drives, which can survive motor parameter changes following faults.
• Correction for thermally induced machine parameter variations when implementing sensorless control schemes. Eminence in this field led to an invited IEEE review paper.
• A new approach to regulation of power from wind farm sites sited in rural weak grid locations, subsequently used to develop Econnect's load controller product.
• Novel estimation and control techniques for production processes. Research with Dupont-Teijin Films produced a factor of 8 improvement in speed-holding for a polymer-film casting-drum, greatly enhancing film thickness control.
• A solution to the serious problem of analysing and controlling successive period-doubling bifurcations in power factor converters, leading to a control technique which greatly extends the stable operating region.