Research On Sensorless Control Of Three-stage Synchronous Machine At Starting Stage

With the continuous development of the related research on more-electric aircraft and all-electric aircraft,more and more attention at home and aboard has been paid to the aviation variable frequency AC power supply,among which the three-stage synchronous motor has become the only candidate model in the aviation power start/generation integrated system due to its mature technology.In the starting process of three-stage synchronous motor,it is necessary to install position sensor to determine the rotor position angle,which limits the development of the integrated system of starting and power generation due to its disadvantages such as increased volume and weight and easy to be affected by the working conditions.Experts and scholars at home and abroad have carried out a great deal of researches on the sensorless technology of three-stage synchronous motor.Although the technology related to the back EMF detection method in the case of medium and high speed has been quite perfect,the back EMF is too small to detect in the process of motor starting.Thus,this paper focuses on sensorless control technology in the process of three-stage synchronous motor starting stage.First of all,this paper briefly introduces the structure,mathematical model and start/generation principle of the three-stage synchronous machine.To address the problems of torque fluctuation and low signal-to-noise ratio of the response signal caused by the injection signals into the main generator of three-stage synchronous machine,a two-way calculation method based on the injection of high-frequency signals from the main exciter side and the extraction of high-frequency response signals from the two-phase stationary coordinate system on the stator side of the main generator is proposed to estimate the rotor position.Based on the method,a simplified study is carried out and a single-way closed-loop method is proposed to estimate the rotor position.Combined with the initial rotor position calibration method,the sensorless starting control of three-stage synchronous method is realized.Aiming at the problem of phase delay caused by the band-pass filter and low-pass filter in the process of position response signal extraction,a generalized second-order integrator is used instead of the traditional filter and the parameters are adapted according to the proposed methods in this paper.Based on the theoretical analysis,a simulation model under the MATLAB/Simulink environment and the hardware platform of the sensorless starting control of the three-stage synchronous machine are built and the software program for starting control,excitation control,and position angle estimation algorithms is designed.The sensorless starting control technology of the three-stage synchronous machine proposed in this paper is experimentally verified,and the two position angle estimation algorithms are compared and tested from the position estimation accuracy and the applicable speed range.Experimental results show that both of the position estimation methods have high accuracy of position angle estimation and wide range of speed adaptation.