Now, I want to discuss the geometriccharacteristic of high speed motor. as we know that high speed motor issmaller than the normal speed motor(the definition of normal motor may havesome problem, but I know that you can understand it) with the same power, andthe diameter is always less than the normal motor, the length is longer thanit. The first question, why is highspeed motor smaller than normal motor? The rated power of the motor equalsCe*D*D*L*N. Ce is motor constant. D is the diameter of rotor. L is the lengthof rotor. N is the rated speed. So, if the rated power is the same, Ce isnearly the same because of the motor design experience. For high speed motor, Nis large, so D*D*L is small. D*D*L stands for the volume of the motor.So we can explain it right now. The other question, why is the diameteris always less than the normal motor, but the length is longer than it? For high speed motor. If the motordiameter is too big. There may have some problem about the mechanical stress. Bythe way, a big diameter means big inertia. The mechanical time constant issmall with small diameter. Small inertia can make the motor start quickly. Consideringthe cost, small diameter have some advantages in reducing the mass of the copperat stator terminal, and the flux leakage is also reduced at terminal.
|