| Magnetic Bearing(MB) is a typical mechatronics product. It is a kind of new style high performance bearing whose rotor is suspended by magnetic force in space. Compared with conventional bearings, MB has the merits of no contact, no friction, long life, less energy consumption, low buzz, no lubrication and so on, and has been fit in a lot of fields. The traditional molecular pump with popular bearing can not meet the challenge of semiconductor manufacturing because of the vibration, short life, unpure vacuum and so on. So it is very important to design the magnetic bearing and power amplifier for molecular pump.Firstly, considering the molecular pump is small and the elimination of heat condition is bad, this paper presents the structure of the MB, including the material of the rotor and stator, the number of magnetic poles, the stator slot shape of MB, the layout of the magnetic poles, the coins winding and so on.Sencondly, an optimum model of MB is founded in order to make the parameters best. The principle of design is making the capacity of MB minimum in the condition of satisfying the maximum levitated force and temperature of coin below the permissible.At last, a comparison of advantages and disadvantages of various modulate techiniques used in the switching power amplifier at present. Then, Pulse Width Modulation(PWM) switching power amplifier is designed and debugged. Characteristics of PWM power amplifier are also analyzed, and the results show that the frequency band is wide, the linearity of I-O is good, efficient is high, ripple of current is low, it meet the design requirements of MB.
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