Study And Applications On Digital Control Technology And Power Amplifier In Magnetic Levitation Support System

The power amplifier of the magnetic levitation supporting system is studied mainly in the paper, including of the principle,the method of design and the technology of application, which is applied specially in the upscale CNC, for example the high-speed and high-precision electronic principal axis of machine (rotary bearing) and high-precision and high-speed plane (the guide of machine) (plane bearing).As to an active magnetic levitation system, the active magnetic levitation theory and supporting technology are the core theory and technology. According to the hardware, which consists of four factors chiefly: Place sensor and examination, signal control and modulate, power source and power amplifier, bearing and rotor. The problem existing in the power amplifier is analyzed and researched before the technology of controller and theory of power amplifier are discussed in the paper, thereby, the feasible scheme for resolving problem is proposed. Including of the analogy power amplifier of magnetic levitation bearing plane system which is—resolving the nonlinear problem to improve the rang of stability by "intelligent power amplifier". Finally, the correlation conclusion is gained by experimental data of Chinese 863 plan item—"the magnetic levitation bearing of upscale numerical control machine " (the item number: Experimental data2001AA423310).In the active magnetic levitation system, the steady suspend force is gained by regulating electric current of field coil in the part of the supporting body, Whose performance is close correlative with power amplifier. Usually, the gap between the supporting body and supported body is changing with the high-speed movement of supported body. The electric current of field coil is regulated according to the real-time position of being supported and the aim of steady levitation and dependable work is achieved. Hence, the power amplifier of the active magnetic levitation system is the key components to decide the performance of the magnetic levitation supporting and also is the core technology which is attentioned by researcher. In the active magnetic levitation system presently, there are two kinds of prevalent power amplifiers: the analogy power amplifier and the switch power amplifier. Although above two kinds are applied universally by more specialists, the nonlinearity of magnetic material makes the defect of less dynamic range arise in the actually application, which cause the development of magnetic suspension technology is not satisfactory. The nonlinear switch power amplifier which is proposed by this Dissertation is specially aimed at nonlinear problem of magnetic material, accordingly, which resolve the difficult and key problem of the magnetic levitation system—the problem of nonlinear effect.The switch amplifier works in state of on-off by switching characteristic of transistor. Thereby the power loss and heating etc of the switch amplifier are solved some degree, The nonlinear switch power amplifier is in the person of intelligentize for the switch amplifier. It will automatic regulate the gain of the switch power amplifier to remove the nonlinear effect according to the nonlinearity of magnetic material.In the nonlinear switch power amplifier, there are two kinds of methods to regulating directly the gain of the switch power amplifier: one is to control directly the on time and the off time to change the electric current of electro-Magnetic coil, which is called the Pulse width modulating technology, also is called PWM technology, the other is the fixed on-off time, regulating the coil current by change voltage, which is called voltage modulating technology. One of commons above is the transistor working in the switch state of high frequency.The main significance of the paper rests with: it proposes the design idea of a kind of novel intelligent power amplifier, and establishes the basic theory and method of design, which causes this kind of power amplifier compensate with the nonlinear magnetic permeability of elector-magnet core and regulate power voltage real-time according to real require. Uniting the numerical control technology and the power amplifier-technology and switch power technology. It realizes intelligence, miniaturization, high efficiency and large power.