Permanent-magnet synchronous motor

A brushless electric motor is an electric motor driven by an electrical input, which lacks any form of commutator or slip ring. The motor requires some form of alternating current to turn, either from an AC supply, or an electronic circuit.

A brushless DC electric motor contains a synchronous motor and integrated power electronics that operate the motor from a direct current supply.

A "permanent-magnet synchronous motor" (PMSM) or "permanent-magnet motor" (PMM) is a synchronous motor that uses permanent magnets rather than windings in the rotor. Electronic excitation control with integrated power inverter and rectifier, sensor, and inverter electronics is required for practical operation. Form-factors for the PMSMs are either axial flux, radial flux, transverse flux, or flux switching depending on the arrangement of components, with each topology having different tradeoffs among efficiency, size, weight, and operating speed. Also in the axial flux or radial flux form-factor, other brushless motors are the brushless wound-rotor doubly-fed synchronous motor system and the magnetic reluctance, which require electronic excitation control for practical operation, and the asynchronous induction motors, which is with or without electronic excitation control depending on the application. Conventional methods of electronic AC excitation control of electric motors, such as volt/frequency control, were available prior to the 1950s with at least mercury vapor thyratrons switching devices and modern age state of art control (or Field Oriented Control) became available in the late 1960s. Permanent magnet motors have been in existence since the introduction of electric motors more than one-hundred years ago.

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