Two Magnetic Levitation Suspension Of The Moving Platform And Drive Control

Magnetic suspension has been paid more and more attention because of its many merits such as no mechanical contact, no wear, low power loss, no need of lubrication and long service life, etc. The two-stage maglev system is suitable for high-speed and high-accuracy positioning. It's important to analysis the system and design right control and amplification circuit as to acquire stable system performance.The analysis of the system control current indicate that proportional-derivative control is needed at least, the magnetic force generated by proportional controller can counteract negative displacement stiffness and make the system possess positive stiffness after improved; the magnetic force generated by derivative controller can provide positive damping for system, which makes system become more stable. Integral control is also needed to reduce steady state error and enable system to have good dynamic stiffness. Finally, PID control is determined for the system. The PID parameters for system have been determined theoretically after analyze, controlling circuit has been designed according to the PID parameters.The power amplifier is the key part which influences the performance of maglev system. A half-bridge switching power amplifier has been designed in order to reduce the current ripple for better control. The PWM driving signals, which are generated in TL494, control MOSFET on or off so that the applied current can get through differential coil or not.Linear motor can drive equipment directly, it has advantages in high efficiency, low transmission error, long stoke, high speed and high-accuracy. PMLSM has been chosen as the driver for system because it's more valid and easier to control. A fine positioning accuracy of the system has obtained finally.The testing results of the physical system show that the maglev system working stably and favorable.