| Compared with the traditional brushless excitation system,the brushless excitation system which cancels the brush and slip ring,improves the reliability of excitation system greatly.Therefore,the brushless excitation system is widely used in ship power,aircraft dc power supply,nuclear power and important fields.Most of the existing researches on the operation state are focused on the three-phase brushless excitation system,and there is no analysis of the commutation process for the multiphase angular rectifier system.Moreover,the transfer function model for the multiphase angular brushless exciter often follows the model for the traditional 3-phase brushless exciter.The commutation process,basic characteristics,equivalent model and parameters of the 11-phase angular brushless excitation system are studied in this paper,which have guiding significance for the structural design of the electronic commutator and the motor and provide an important basis for the optimal design of the multiphase angular brushless exciter.In order to facilitate the operation state analysis of the 11-phase angular brushless excitation system,several appropriate and reasonable assumptions are made in this research.On this foundation,the working principle of the 11-phase angular rectifier system is described.According to the structural characteristics of the armature winding in the 11-phase angular brushless excitation system,the diode opening law is analyzed.Based on the difference of the number of diodes in the 11-phase angle rectifier system,the operation state of the rectifier system is distinguished according to the number of conducting diodes.The process of diode conduction and commutation in each operation state is analyzed and calculated in detail.The phenomenon of diode advance conduction in the 11-phase angular rectifier system is analyzed.The diode current is a bimodal waveform.Based on the commutation process analysis of the 11 phase angular rectifier circuit,its basic characteristics are analyzed and calculated.According to the different operation state changes of the 11-phase angular rectifier system,the change of commutation overlap angle is studied.Different commutation processes will cause the load voltage to drop in different degrees.The load side voltage obtained by rectification is calculated analytically.In addition,the effective value of rectifier diode current is calculated under different operation states.The critical operation states are analyzed and the critical conditions are obtained.According to the actual parameters and structure of the 11 and 39 phase angular brushless exciter,their field circuit coupling finite element model is established in the finite element software ANSYS Maxwell.The establishment process of the finite element simulation model is introduced in detail.The electric quantity waveforms of 11-phase angular brushless exciter in normal conditions are obtained by simulation calculation,and the corresponding experiment is carried out on the 11-phase prototype.Three operation states of 11-phase angular brushless excitation system are displayed.Through the comparison of the simulation and experiment results,the simulation model accuracy is verified.Finally,the simulation calculation for the operation state of the 11 and 39 phase brushless excitation system under the actual operation condition is carried out and the operation state of the 11-phase angular brushless exciter is calculated analytically.The correctness of the theoretical analysis is verified.Finally,according to the operation state characteristics of the 11-phase angular brushless exciter,the physical meaning and various parameters calculation method are put forward respectively with regard to the different structures of the 11-phase angular brushless excitation system,which is of great significance to analyze the dynamic response of the multiphase angular brushless excitation system. |
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