In turbo molecular pump what kind of DC brushless motors (sin/tropize) are used? I know how work DC brushless motor in steady state, but don't know how it runs in first. And does it run in each speed in first time? How do I do it?

 

Conventionally trapezoidal for high speed, sin for lower speed. It's also about your circuit driver. If you can, you can achieve high speed with sin.