磁浮平台脈寬調變功率放大器暨可變結構控制器開發與設計

PWM Power Amplifier and Variable Structure Controller Design for Magnetic-Levitated Platform System

吳政儒(Cheng-Ju Wu)

指導教授 ： 范憶華

中原大學/工學院/機械工程學系/碩士(2007年)

https://doi.org/10.6840/cycu200700709

摘要

近年來，磁浮運輸及磁浮致動平台常見於需要穩定、快速驅動、定位精度高及低摩擦之機械相關設備。本研究設計一組五自由度的磁浮平台，針對負載變動產生的微偏移與微擾動進行校正控制，減少系統振盪且提高定位精度。磁浮平台為一不穩定系統，不但具有高度的非線性及外部干擾問題，各自由度之間亦有動態耦合的情形，故利用順滑模式控制理論將耦合項視為干擾外力進行解耦控制，以簡化控制器之設計。另外為了消除暫振現象，在切換函數中加入順滑層，以減低因切換函數造成的切跳現象及高頻干擾。實驗結果顯示，磁浮平台系統垂直定位精度可以達到小於0.4 ，負載最大可至500N。另外，針對變動負載(10kg~30kg)所造成之影響，垂直定位精度可以達到小於1 。
在功率放大器方面，本研究利用脈波寬度調變技術設計出磁浮系統所使用的電流驅動放大器以取代早期的線性放大器，利用切換式功率放大器可在大電壓，大電流的工作下使用之特性，提高磁浮系統力量時間變化率並提升系統頻寬。
本研究之驅動器架構以運算放大器構成之內部閉迴路控制器搭配全橋兩象限截波器，並以三階脈波寬調變控制技術，完成具有快響應、高頻寬以及良好的暫態響應，而且有低失真、低雜訊及低漂移的電流驅動控制器。實驗結果顯示在不同負載條件下，本研究所提出之電流驅動控制器動態響應遠優於傳統推挽式線性放大器，在不同電磁線圈負載下，系統頻寬可達數kHz。

關鍵字

磁浮平台 ； 功率放大器 ； 可變結構控制 ； 脈寬調變

並列摘要

In recent years, the active magnets suspended platforms are often seen in the mechanism that designed for high-speed, high position precision or low friction, such as micro/nano linear stages, especially. This research was aimed at the controller design for a five degree-of-freedom magnetic levitated platform. The magnetic levitated platform system basically is an unstable system, it is not only a highly nonlinear system, also is a dynamic coupled system. Furthermore, there are four actuators and only three controlled factors in the vertical position of the platform. Therefore, a decoupled structure was proposed to resolve the control question. Based on the decoupled model, we designed a global variable structure controller to decrease the influence of the load changes and reduce the system vibration, and promote the positioning precision. Moreover, a saturation function was added to controller to form a sliding layer and to eliminate the chatter phenomenon. The experimental results showed the suspension precision was about less 1 慆 as the load changed from 10kg to 30kg.
In the power amplifier, this research used the pulse width modulation technique to design a switched current driver design for the electric magnets of magnetic suspension system. Dye to the phenomenon of the MOSFET, the driver can operate in the great voltage and under the bigger electric currents than the traditional push-pull linear driver. Furthermore, the relationship of the force slew rate and the supply voltage are proposed.
The driver is composed of the interior loop control circuit of the proposed driver made by the operational amplifier, the two-quadrant chopper, and the three-level PWM controller. The experimental results show the proposed driver better than the traditional push-pull linear driver in the response rate, the system bandwidth, the transition response as well as the low current distortion. The experimental results also shown the system bandwidth of the proposed driver may reach several kHz under the different loading condition.

並列關鍵字

Magnetic-Levitated Platform ； Global Variable Structure ； Pulse Width Modulation ； PWM Power Amplifier

參考文獻

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