Research On The Control System And Algorithm Of Hard Disk Drive Magnetic Bearings

Active Magnetic Bearing (AMB) has such a lot of advantages that it is called a technology revolution of the bearings. Applying AMB to the support of HDD (hard disk drive), which can avoid the contact of bearing and HDD rotor, it has a lot of advantages in comparison with other bearing types. But the technology of AMB is an advanced technology, which relates to many science fields such as mechanics, rotor dynamics, electromagnetic, electronics, control theory, computer science and so on. AMB can work well only with the help of control system. So the control is a key technology of AMB. The performance of controller affects the dynamic performance of AMB system and the control precision of rotor, which is very important for the application of AMB in HDD.This paper takes the HDD-AMB experiment device as research object, studies and develops the proper digital control system to meet the requirement of AMB. It also studies control algorithms of the HDD-AMB control system. Research achievements are as below:It deduces the mathematic model of single degree-of-freedom(1-DOF) AMB with proper predigest and hypothesis by applying electromagnetic theory, further more , it takes the five degree-of-freedom(5-D0F) AMB system as five independent 1-DOF AMB systems from control implement. It offers the academic theory for designing the control system.In order to achieve the high speed and high precise control in the HDD-AMB control system, this paper takes the chip TMS320LF2407A as the Digital Signal Processing (DSP) controller, and also designs the hardware circuit outside the DSP chip. Further more, it designs the anti-jamming of the signal sampling base on the work theory of the eddy-current displacement sensor.According to the characteristic and requirement of the HDD-AMB control system, The HDD-AMB pulse width modulation (PWM) power amplifier has been developed. What' s more, this paper introduces the composing theory and the structure of power amplifier unit, points out the key factorin the realization of power amplifier.In order to achieve that the parameters of the digital control system can modify online and supervise real-time, The CAN bus interface card have been designed to complete the communication between the computer and DSP. Some key factors in the design of CAN bus communication have been discussed too.According to the HDD-AMB feature and designing desire, The control algorithms that suit to the HDD-AMB system have been proposed. Based on the analysis of the model of the control system, the algorithm of PID, Volatile integral PID and single neuron-PID composite control have been discussed. These algorithms have been simulated and implemented by software. The results show that single neuron-PID composite control not only has the advantages of the PID control, but also has the capability of learning and adaptivity. It has better dynamic and steady-state performance.