Research On The Power Amplifier Of AMB Hard Disk

The rapid improvement of magnetic hard disk drives in the last years regarding storage density, spindle speed, cost, etc., is forcing disk drive industry to evaluate new technologies for different system components which might become liming factors in the future. Mechanical problems of the spindle bearings, such as vibrations, run-out, and wear, have become one of these limiting factors. Active magnetic bearings have the potential of providing solutions to some of these problems. Their major advantages over conventional bearings results from the fact that there is no mechanical contact between rotor and stator. The hard disk will be characterized by high precision, few heat, low dissipation, less noise and high cleanness, which cannot be realized through hard disks supported by other bearings.It is feasible to apply the magnetic suspension technology to the hard disk drives based on the principle and structure. The performance of hard disk with AMB is related not only to the mechanical structure and manufacturing process, but also to the precision of sensor, the control arithmetic and the performance of power amplifier in the control system. Further more, an excellent power amplifier is indispensable to the realization of the high precision and high speed of AMB hard disk.This paper is written based on the below works: a kind of power amplifier which can be used in the AMB hard disk drive has been developed according to the characteristics of AMB hard disk based on the modern electronic theory and technology, in order to satisfy the high precision and high speed which is required by hard disk.In this paper, the author introduces the development and application of AMB, analyzes present situation of study on the AMB hard disk , builds up the mathematical model of single freedom of degree AMB, analyzes the universal principle and way to the design of power amplifier. At the same time, a kind of PWM switching power amplifier has been designed and made, and it has passed the modification and test. In addition, for solving the problem of PWM power amplifier, a way of phase-shift to improve the switching circumstance, lower the wastage is brought forward. Finally, the author analyzes the possibility to cut down power waste of amplifier further, improve the efficiency and reliability, decrease the volume of power amplifier.