The Research Of The Swing-Arm Voice Coil Motor

As a new type of direct-drive motor with special structure, voice coil motor, which is similar to the voice coil of loudhailer in work principle, is characterized by being of high acceleration, high speed, smooth force, fast actuation and so on. The VCM possessing advantages of small-volume, light-weigh and fast-action can achieve high orientation precision and equality impetus. After a detailed description of the working principle and structural characters of voice coil actuator, this paper has presented the method for choosing VCM and spiral voice coil actuator. It also introduced the application of voice coil actuator. At present, the VCM exist widely in consumption and production market, especially in the top grade home electrical appliance and computer market.The main work and research results in this paper are as follows:Firstly, the development and application of VCM are briefly reviewed. The background as well as the status of the research on the VCM is highlighted.Secondly, the classification and the principle of work of VCM are introduced. The main problem is the three dimension magnetic field distribution of SA-VCM. The simulation software has been used. The VCM simulation model has been set up, based on the example of 3.5 inch hard disk drive of Quantum.Thirdly, this article introduced two kind of control strategy of swing arm voice coil motor in hard disk drive: Analog electric current control and digital electric voltage control. Current command of the voice coil motor has been preferred so far, due to its good performance in term of robustness. The characteristics of the system to be controlled by the servo-controller are rather independent from all possible variations of electrical impedance of the VCM and power supply voltage. The voltage driver consists of a voltage-controlled power stage, with a pre-filter placed at its input, plus a back e.m.f feed-back compensator. The VCM resistance may change by±30% during HDD operation, due to self-heating. This paper presents an on-line estimation procedure, based on an Extended Kalman Filter(EKF), capable of estimating the VCM coil resistance with a high degree of accuracy.Lastly, Each kind of control strategy carries on the simulation experiment with MATLAB and Simulink simulation software, compared with good and bad points.