- 學位論文
磁浮平台之脈寬調變驅動器設計
Design of Pulse Width Modulus Driver for Maglev Platform
摘要
現今脈寬調變技術已非常成熟，使得脈寬調變驅動器取代了傳統的線性放大器應用於各類驅動系統。由於脈寬調變技術之產品有性能高，價格低的優點¬，所以目前已經被廣泛運用在磁浮驅動系統。 早期的磁浮驅動系統係採用小功率的線性放大器，但線性放大器的效率低，而且晶體有發熱的問題，在這些因素下，使得線性放大器漸漸被替換掉。本文所使用的電流驅動器係採用切換式電源供應器技術架構，切換式功率放大器在電壓與電流較大的情況下，有比線性放大器更高的效率，但是主要的缺點在於開關切換會造成損失以及電磁干擾等問題。目前解決這兩個缺點的方法是經過有效的電路設計以及EMI濾波器來減低上述問題所造成的影響。使用傳統的線性放大器的問題是電源供應器所供應的電壓較大時驅動端所用的電晶體在電流較大的情況下容易過熱而燒毀，若是電源供應器所供應的電壓不夠，線圈電流無法加大且變化不夠快速，就會造成磁浮力不足或有相差之問題。 因此本文主要是設計一個脈寬調變電流驅動放大器，此驅動器使用增強型場效電晶體，以解決傳統的線性放大器的問題。本文與一般切換式電源供應器不同的地方在於回授端採用的是電流回授，透過控制器來控制開關的切換，使得設計出來的驅動器能提供較大的電流並具有快速電流變換的能力。
並列摘要
Recently, the pulse width modulation (Pulse Width Modulation, PWM) technology had been matures. Thus, the PWM drivers replace the traditional linear amplifiers in many driver systems. Because the advantages of the products made by the technology are high-performance and low cost, they are widely used in the drivers of the magnetic levitation systems. The drivers consisted by the linear amplifier which used in the early magnetic levitation systems. But the linear amplifiers are low efficiency and have heat issues, the drivers consisted by the linear amplifier were replaced gradually by the PWM drivers. The current driver designed in this thesis is based on the structure of the switching power supply. This kind of drivers has higher work efficiency more than the linear amplifier drivers as they used in high current and voltage. Nevertheless, the main drawback is that they would get energy losses and electromagnetic interference as the switches operating. Presently, these two disadvantages can be reduced by useful circuit design and adding EMI filter in the system. The problem of the traditional linear amplifiers is the transistors may burn out by heat as they used in a higher source voltage and a lager current. To avoid the problem is to lower the source voltage, but the magnet coil currents may be not enough and cannot change quickly, thus the magnetic force may be shortfall and may be changed with phase lag. We design a PWM current driver amplifier which using the enhanced field-effect transistors as the switches in this thesis to solve the problems of the traditional linear amplifiers. The different comparing with the switching power supply systems is we used a circuit feedback system to control the switches operating. It makes the driver with the large current and quickly changeable ability.