Permanent-magnet brushless

The main technologies of electric machines used for electric road vehicles are DC motors, induction motors, permanent-magnet brushless, DC-switched reluctance motors [2]. These different types of electric machines are analyzed in the following sections of this chapter. 

The specific power of rare earth permanent magnet motors can exceed 1 kW/kg. The combination of reliable, low-cost, solid-state controllers and brushless permanent magnet motors will find applications in (i) computer accessories like disk drives, printers, x-y plotters, (ii) consumer goods like hand tools, fans, and air-conditioners, (iii) robotics, traction motors, steel mills, lift motors, and (iv) aerospace flight control actuators. 

Fig. 55. Effect of varying rotor diameter in brushless DC motors based on permanent magnets, (a) Situation for ferrite magnets under various constraints discussed in the main text. The arrow indicates increasing electric loading Q. (b) Envelope of feasible designs (hatched area) based on different permanent magnet materials. The arrows L and BH indicate increasing inductance (L) and increasing (BH)msi%, respectively. (After Howe et al. 1987.)...

Synchronous Motor, Brushless DC-Motors, Synchronous Reluctance, and Permanent Magnet Stepper Motors... 

T. J.E. Miller. Brushless Permanent-Magnet and Reluctance Motor Drives. Oxford Science Publications, Oxford, UK, 1989. 

Brushless DC drives have an advantage in that the motor does not contain brushes. As a result, the drive is less maintenance intensive. The motor contains permanent magnets the size of the magnets determines the horsepower capability of the motor. The maximum power available today is around 600 hp. A schematic of the brushless DC drive is shown in Fig. 3.6. 

The brushless DC motor (BLDC motor) is really an AC motor The current through it alternates, as we shall see. It is called a brushless DC motor because the alternating current must be of variable frequency and so derived from a DC supply and because its speed/torque characteristics are very similar to the ordinary with brushes DC motor. As a result of the brushless DC not being an entirely satisfactory name, it is also, very confusingly, given different names by different manufacturers and users. The most common of these is self-synchronous AC motor , but others include variable frequency synchronous motor , permanent magnet synchronous motor , and electronically commutated motor (ECM). 

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