| Rudder servo system is the most important part of flight control system, all the flight motion of theaircraft depends on the actuator driver fins of rudders. With the advantages of simple control, largetorque and high power density, Brushless DC motor (BLDCM) becomes the attractive candidate forrudder servo system. However, due to the special applications of rudder servo system, the installationof position sensor for BLDCM is strictly limitted, and the serious working conditions demand highreliability of the position sensing method. The sensorless BLDCM (SLBLDCM) technology is thebest way to solve the above inconvenience. Therefore, it is practical to do the research on SLBLDCMin the rudder servo system.Firstly, the development status, operation principles and mathematic models of the rudder servosystem and SLBLDCM are introduced, and the sensorless control strategies of the rudder servosystem are proposed in this thesis. The double-loop system utilizing the outer-loop of postion and theinner-loop of current is established by the software MATLAB. The characteristics of senosrlesscontrol methods between the short pulse sensing and three-step startup are compared for the BLDCMrudder servo system in simulation results, and it provides the theoretical basis for the accomplishmentof the proposed prototype system.Secondly, the digital control system for rudder servo system based on TMS320LF2812is built toverify the validity of the proposed methods. The short pulse sensing method for initial positiondetection and the zero crossing detection of back EMF are verified for the rudder servo system by theexperiments. The dynamic, static performances and bandwidth response are analyzed by applying thestep signal and the sine signal to BLDCM rudder servo system under the proposed sensorless controlstrategies.Compared to experimental results of the rudder servo system with sensor, the proposedsystem has high-performance of position tracking for rudder. |
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