| The high-precision micro-positioning platform is one of the core components of lithography machine.Considering the characteristics of magnetic levitation technology,such as active controllability,micro-vibration and contact-free support,it is considered to be an ideal way to realize the high stability active suspension and high precision position control of the micro-positioning platform.In order to realize the high precision control of the magnetic suspension fine stage,the requirements of the power supply are: wide-range adjustable load current,high resolution control voltage and low ripple output voltage.Therefore,a highresolution multi-channel power supply system is designed based on the requirement of multidegree-of-freedom control for the coil array driver of the high-precision micro-positioning platform.The phase-shifted full-bridge small-signal model is established,and the resolution characteristics and electromagnetic coupling characteristics of multi-channel power supply are studied.The fuzzy PID control method is introduced to achieve the high precision current output.The driving capability of the power supply is determined by the voltage regulation range.The wide voltage regulating range of the power supply can be realized by both the phaseshifting full bridge and the duty cycle full bridge.In this paper,the principle of phase-shift full-bridge and duty-cycle full-bridge of DC/DC converter is introduced,and the main circuit parameters are calculated according to the power supply demand of the high-precision micro-positioning platform.The feasibility of the power supply depends on the hardware design of the main circuit.For the duty-cycle full-bridge converter,the incomplete parasitic capacitor discharge of the switch tube will lead to the failure of pulse width modulation(PWM)control of the power supply.Although the external discharge circuit can solve the problem of voltage regulation,the efficiency of the power supply will be reduced.For the phase-shifting full bridge circuit,its own working process provides a discharge loop for parasitic capacitance,which can complete PWM control without affecting the efficiency of the power supply.By comparing the above two hardware circuits,this paper proves that the phase shifted full bridge has higher resolution and higher efficiency through experiments.Finally,the paper uses the phase-shifted full-bridge circuit for low-ripple experiments.The reliability of the power supply system is determined by the power supply in the form of multiple outputs.In this paper,the design of the multi-channel power supply system input parallel,the output of each power supply to the coil to provide independent adjustable current.The paper analyzes the electromagnetic interference of multiple power supplies,and builds a Saber simulation model to analyze conducted interference.According to the mutual influence between power sources when they work in close range,the simulation model of coupling interference is analyzed by ANSYS software.The accuracy of the power supply depends on high resolution power supply and appropriate control strategy.In the paper,hardware voltage loop compensation and software current loop compensation are designed according to the small-signal model.MATLAB/Simulink model is built.Simulation analysis of phase shifting full bridge circuit is completed by using PID and fuzzy PID algorithm.The experiments verify the completeness of the phase-shifted fullbridge power system.The phase-shifted full-bridge power system has the characteristics of easy control,high resolution and small volume. |
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