Research On Electic Control System Of AMB Based On Nonlinear PID Control

In comparison with the conventional bearings, active magnetic bearings (AMB), which use electromagnetic force to support a rotor freely, are being widely used in rotating machinery. Because of its advantages, AMB is attracted a great deal of attention of scientists and manufactures. It is a composed system including mechanics, electronics, magnetic, and computers.First, the thesis introduces the basic work principle of AMB, analyzes the expressions of magnetic field and electromagnetism force, deduces the mathematics' model based on the expression, and hence, the linear model of AMB. Then, as the key parts of AMB, power amplifier and control system are designed. By comparing with advantages and disadvantages of various modulate techniques used in the switching power amplifiers at present. Sample-hold strategy is adopted due to its fairly simple circuit with high frequency bandwidth and fast dynamic response in a wide load range. The way to design each part of power amplifier circuit is also explained. Besides, when comes to the control system design, a nonlinear PID control arithmetic was put forward based on traditional PID control arithmetic. Simulation comparisons are made to the two different control arithmetics with Matlab. At last, the hardware and software of digital control system based on DSP is designed.Finally, levitation experiment of single freedom degree of AMB is realized, It shows the availability and rationality of system design.