Editing Synchronous motor (section)

==== Permanent-magnet ====
A permanent-magnet synchronous motor (PMSM) uses [[permanent magnet]]s embedded in the rotor to create a constant magnetic field. The stator carries windings connected to an AC electricity supply to produce a rotating magnetic field (as in an [[asynchronous motor]]). At synchronous speed the rotor poles lock to the rotating magnetic field. PMSMs are similar to [[brushless DC motors]]. [[Neodymium magnets]] are the most common, although rapid fluctuation of neodymium magnet prices triggered research in [[ferrite magnets]].<ref>{{Cite journal |last1=Eriksson |first1=S |last2=Eklund |first2=P |date=2020-11-26 |title=Effect of magnetic properties on performance of electrical machines with ferrite magnets |url=http://dx.doi.org/10.1088/1361-6463/abbfc5 |journal=Journal of Physics D: Applied Physics |volume=54 |issue=5 |pages=054001 |doi=10.1088/1361-6463/abbfc5 |issn=0022-3727 |s2cid=225152358|url-access=subscription }}</ref> Due to inherent characteristics of [[Ferrite (magnet)|ferrite magnets]], the [[magnetic circuit]] of these machines needs to be able to concentrate the magnetic flux, typically leading to the use of spoke type rotors.<ref name=":0">{{Cite journal |last1=Luk |first1=Patrick Chi-Kwong |last2=Abdulrahem |first2=Hayder A. |last3=Xia |first3=Bing |date=November 2020 |title=Low-cost high-performance ferrite permanent magnet machines in EV applications: A Comprehensive Review |url=http://dx.doi.org/10.1016/j.etran.2020.100080 |journal=ETransportation |volume=6 |pages=100080 |doi=10.1016/j.etran.2020.100080 |issn=2590-1168 |s2cid=224968436|url-access=subscription }}</ref> Machines that use ferrite magnets have lower power density and torque density when compared with neodymium machines.<ref name=":0" />

PMSMs have been used as gearless elevator motors since 2000.<ref>{{cite web |last=Mehri |first=Darius |date=18 September 2000 |title=Belts Lift Performance |url=https://www.designnews.com/document.asp?doc_id=226553 |archive-url=https://web.archive.org/web/20130629134620/https://www.designnews.com/document.asp?doc_id=226553 |archive-date=29 June 2013 |access-date=10 May 2016 |website=DesignNews.com}}</ref>

Most PMSMs require a [[variable-frequency drive]] to start them.<ref>
R. Islam; I. Husain; A. Fardoun; K. McLaughlin.
[https://ieeexplore.ieee.org/document/4757411 "Permanent-Magnet Synchronous Motor Magnet Designs With Skewing for Torque Ripple and Cogging Torque Reduction"].
Industry Applications, IEEE Transactions on.
2009.
{{doi|10.1109/TIA.2008.2009653}}
</ref><ref>
Ki-Chan Kim; Seung-Bin Lim; Dae-Hyun Koo; Ju Lee.
[https://ieeexplore.ieee.org/document/1704668 The Shape Design of Permanent Magnet for Permanent Magnet Synchronous Motor Considering Partial Demagnetization"].
Magnetics, IEEE Transactions on.
2006.
{{doi|10.1109/TMAG.2006.879077}}
</ref><ref>
P. Pillay; R. Krishnan.
[https://ieeexplore.ieee.org/document/90357 "Application characteristics of permanent magnet synchronous and brushless DC motors for servo drives"].
Industry Applications, IEEE Transactions on.
1991.
{{doi|10.1109/28.90357}}
quote:
"The permanent magnet synchronous motor (PMSM) and the brushless DC motor (BDCM) have many similarities; they both have permanent magnets on the rotor and require alternating stator currents to produce constant torque."
</ref><ref>
Y. Honda; T. Nakamura; T. Higaki; Y. Takeda.
[https://ieeexplore.ieee.org/document/643011 "Motor design considerations and test results of an interior permanent magnet synchronous motor for electric vehicles"].
Industry Applications Conference, 1997. Thirty-Second IAS Annual Meeting, IAS '97., Conference Record of the 1997 IEEE.
1997.
{{doi|10.1109/IAS.1997.643011}}
</ref><ref>
M.A. Rahman; Ping Zhou.
[https://ieeexplore.ieee.org/document/491349 "Analysis of brushless permanent magnet synchronous motors"].
Industrial Electronics, IEEE Transactions on.
1996.
{{doi|10.1109/41.491349}}
</ref> However, some incorporate a squirrel cage in the rotor for starting—these are known as line-start or self-starting.<ref>{{cite journal |last1=Hassanpour Isfahani |first1=Arash |last2=Vaez-Zadeh |first2=Sadegh |date=Nov 2009 |title=Line Start Permanent Magnet Synchronous Motors: Challenges and Opportunities |journal=Energy |volume=34 |issue=11 |pages=1755–1763 |doi=10.1016/j.energy.2009.04.022|bibcode=2009Ene....34.1755H }}</ref> These are typically used as higher-efficiency replacements for induction motors (owing to the lack of slip), but must ensure that synchronous speed is reached and that the system can withstand [[torque ripple]] during starting.

PMSMs are typically controlled using [[direct torque control]]<ref name="IEEE Conference Publication 2020-1">{{cite book |last1=Suman |first1=K. |url=https://ieeexplore.ieee.org/document/6484405 |last2=Suneeta |first2=K. |last3=Sasikala |first3=M. |title=2012 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES) |chapter=Direct Torque Controlled induction motor drive with space vector modulation fed with three-level inverter |date=2020-09-09 |isbn=978-1-4673-4508-8 |pages=1–6 |doi=10.1109/PEDES.2012.6484405 |access-date=2020-09-23 |s2cid=25556839}}</ref> and [[field oriented control]].<ref name="IEEE Journals & Magazine 2020">{{cite journal |last1=Wang |first1=Zheng |last2=Chen |first2=Jian |last3=Cheng |first3=Ming |last4=Chau |first4=K. T. |date=2020-09-09 |title=Field-Oriented Control and Direct Torque Control for Paralleled VSIs Fed PMSM Drives With Variable Switching Frequencies |url=https://ieeexplore.ieee.org/document/7113904 |journal=[[IEEE Transactions on Power Electronics]] |volume=31 |issue=3 |pages=2417–2428 |doi=10.1109/TPEL.2015.2437893 |s2cid=19377123 |access-date=2020-09-23|url-access=subscription }}</ref>