Acoustic Noise and Vibration of Permanent Magnet Brushless Machines Having a Fractional Number of Slots per Pole
Lead Research Organisation:
University of Sheffield
Department Name: Electronic and Electrical Engineering
Abstract
More than 65% of electrical energy which is consumed in developed countries is used by electrical machines. They are being employed in increasingly varied, and evermore challenging, applications, and are often embedded as an integral part of larger systems. However, the noise which is radiated by electrical machines is recognised as of enormous importance, irrespective of whether they are high power and provide propulsion torque, medium power for closed-loop servo control or low power for drives in consumer products. Indeed, noise standards now exist in many countries, whilst the maximum permitted noise level is usually stipulated in specifications. Thus, it is important that electrical machine manufacturers know, within given limits and at the design stage, the noise spectrum which a machine will produce, and can identify optimum and cost-effective ways of meeting given noise criteria.Although there is no dearth of text-books on acoustics, very few are directed at electrical machines, and those that are only provide designers and engineers with general information regarding the electromagnetic origins of noise, the mechanical behaviour of electrical machine, and their noise radiation characteristics. They are, therefore, of limited value when addressing a specific noise problem.Design engineers need more specific information about, and a greater understanding of, noise-causing forces and their dependence on design features, the response to those forces and the resulting acoustic power. However, the prediction of acoustic noise, as well as the estimation of electromagnetic, mechanical and acoustic parameters, is very difficult, not least because only a very small fraction of the electrical energy is converted into acoustic energy.Improved electrical machine design and magnetic materials, most notably rare-earth magnets, has led to new machine technologies, of which permanent magnet brushless machines are generally regarded as being the most energy efficient and having the highest power density. Competition is also leading to smaller machines per unit output power, and, hence, increased electric and magnetic loadings, relatively thin frames, and higher flux densities, all of which aggravate noise and vibration problems. Further, new concepts for permanent magnet brushless machines are emerging for which techniques for predicting magnetic noise generation either need to be developed further or do not exist. This is the case with the type of machine which is to be researched. It offers significant performance advantages and commercial potential. However, the ratio of its stator slot number to rotor pole number differs from that of conventional permanent magnet brushless machines, and results in many more frequency components in the radial and circumferential vibration forces, different vibration modes, and possibly unacceptable noise. In addition, there are other potentially significant sources of vibratory force, due to magnetic asymmetry, for example. Further, the vibration and acoustic noise behaviour of external rotor topologies will be very different to that of internal rotor machines.Thus, it is proposed to undertake a systematic programme of work which aims to establish reliable vibration and noise and reduction techniques for this class of machine and to demonstrate their low noise capability.
Organisations
Publications
Wu L
(2011)
Analytical prediction of electromagnetic performance of surface-mounted PM machines based on subdomain model accounting for tooth-tips
in IET Electric Power Applications
Wu L
(2014)
Analytical Modeling of Surface-Mounted PM Machines Accounting for Magnet Shaping and Varied Magnet Property Distribution
in IEEE Transactions on Magnetics
Wu L
(2010)
An Analytical Model of Unbalanced Magnetic Force in Fractional-Slot Surface-Mounted Permanent Magnet Machines
in IEEE Transactions on Magnetics
Wu L
(2012)
Analytical Model for Predicting Magnet Loss of Surface-Mounted Permanent Magnet Machines Accounting for Slotting Effect and Load
in IEEE Transactions on Magnetics
Wu L
(2012)
Analytical Modeling and Analysis of Open-Circuit Magnet Loss in Surface-Mounted Permanent-Magnet Machines
in IEEE Transactions on Magnetics
Wu L
(2012)
Comparison of Analytical Models of Cogging Torque in Surface-Mounted PM Machines
in IEEE Transactions on Industrial Electronics
Wu L
(2014)
Simplified Analytical Model and Investigation of Open-Circuit AC Winding Loss of Permanent-Magnet Machines
in IEEE Transactions on Industrial Electronics
Wu L
(2012)
Analytical Model of Eddy Current Loss in Windings of Permanent-Magnet Machines Accounting for Load
in IEEE Transactions on Magnetics
Wu L
(2011)
An Improved Subdomain Model for Predicting Magnetic Field of Surface-Mounted Permanent Magnet Machines Accounting for Tooth-Tips
in IEEE Transactions on Magnetics
Zhu Z
(2014)
Influence of Pole and Slot Number Combinations on Cogging Torque in Permanent-Magnet Machines With Static and Rotating Eccentricities
in IEEE Transactions on Industry Applications
Description | Analytical modelling techniques for the field distributions and performance calculation for permanent magnet machines. |
Exploitation Route | Analytical modelling techniques for the field distributions and performance calculation for permanent magnet machines have been used by Motor Design Ltd in their MotorCAD software. Later this has also resulted in a KTP project with Cobham (Vector Field, 2014-2016) to develop CAD software that addresses design of brushless permanent magnet motors using the optimal combination of analytical and finite element based techniques. |
Sectors | Aerospace, Defence and Marine,Education,Energy,Environment,Healthcare,Manufacturing, including Industrial Biotechology,Transport |
Description | The research outcomes have been utilised by Siemens Wind Power for solving the acoustic noise problem in wind turbine system. On 11 January 2011, a presentation on "Acoustic noise and vibration in permanent magnet brushless machines" was given to engineers (around 15 people) at Siemens Wind Power in Denmark, and followed by a two days workshop, 29-30 June 2011 at Sheffield for engineers and post doctor researchers, and PhD students (around 30 people). It had helped solving the acoustic noise problems in wind power generation system. Further, Siemens wind power has sponsored a part-time PhD (Siemens engineer, Mr Edom Lemma) at Sheffield on acoustic noise of wind power generator, followed by the sponsorship of a full-time PhD student (Mr Jaime Maravi). Meanwhile, Nissan has sponsored a full-time PhD student (Mr Iain Urquhart) on the acoustic noise and vibration of interior permanent magnet machine for electric vehicle application, and Jaguar LandRover has sponsored a full time PhD student (Mr James Dexter) on acoustic noise and vibration of switched reluctance machines for electric vehicle application. All these PhD students are studying at Sheffield currently and in good progress. |
First Year Of Impact | 2017 |
Sector | Education,Energy,Environment,Healthcare,Manufacturing, including Industrial Biotechology,Transport |
Impact Types | Societal,Economic |
Description | Brose Fahrzeugteile GmbH & Co. |
Amount | £100,000 (GBP) |
Funding ID | X/005517-12 |
Organisation | Brose Fahrzeugteile |
Sector | Private |
Country | Germany |
Start |
Description | Brose Fahrzeugteile GmbH & Co. |
Amount | £100,000 (GBP) |
Funding ID | X/005517-12 |
Organisation | Brose Fahrzeugteile |
Sector | Private |
Country | Germany |
Start |
Description | Motor Design Ltd |
Amount | £96,000 (GBP) |
Funding ID | X/003609-13 |
Organisation | Motor Design Ltd |
Sector | Private |
Country | United Kingdom |
Start |
Description | Motor Design Ltd |
Amount | £96,000 (GBP) |
Funding ID | X/003609-13 |
Organisation | Motor Design Ltd |
Sector | Private |
Country | United Kingdom |
Start |
Description | Siemens |
Amount | £549,700 (GBP) |
Funding ID | R/123905-11-1 |
Organisation | Siemens AG |
Sector | Private |
Country | Germany |
Start |
Description | Siemens |
Amount | £549,700 (GBP) |
Funding ID | R/123905-11-1 |
Organisation | Siemens AG |
Sector | Private |
Country | Germany |
Start |