The Ship-used Power Angle Compensation Excitation System Design With Frequency Conversion Velocity Modulation Synchronous Motor

In the field of high power, AC drive has replaced DC drive and with the progress of the technology and manufacture, more and more electric drive adopts the technology of velocity modulation. Synchronous motors have a large proportion in the electric drive. The velocity of traditional synchronous motor is constant and unmodulated. There are many problems when the synchronous motors operate in the condition of constant frequency, such as the difficulty of startup, outer-sync and agitation in the process of operation, startup and outer-sync of the constantly frequent synchronous motor controlled by excitation controller, but the waste of energy is serious and outer-sync is unthorough settled. Many companies have greatly researched the technology of frequency control of large synchronous motors and excitation regulation of synchronous motors has been applied in frequency-converter, but the plant of frequency conversion is very expensive. The research is very attractive, if the convenient universal frequency-converter can be sued in frequency control of synchronous motor, and the problem of agitation and outer-sync can be settled.From the principle of electoromechanics, it is can be obtained that the power-angle 8 influences the stability of the motor, and the 8 is the angle between the synthrtical magnetic potential F_μand motivative magnetic potential F_f. If the the power-angleδcan be measured or calculated and even can control the power-angleδ, it must can regulate the motor and solve the agitation and outer-sync of the motor. To resolve the speed-regulating and the desynchronizing of the motor, "the power angle cut-off degenerative feedback" control strategy is proposed in this paper.The key technology of the power angle cut-off degenerative feedback" is based on how to estimate the power angle fast and accurately. In this paper, it adopted the pure electric measure method, it collected the output voltage of the synchronous motor, current or any other electric quantity, moreover it obtained the power angle by theory analyze and calculate. Then it proposed the scheme-solving based on steady-state formula or the solution of vectogram iterate, in order to get the power angle fast and accurately.Then, the excitation hardware flat roof with C8051F015 single chip processor is set up, it included the measure and pretreatment cell of the current and voltage analog quantity, the lectotype of display and parameter input cell as well as transducer, it provide the physics basic for the whole project.The soft ware is very important in the realization of system function. The core of the whole soft ware is the iterative solution of the power-angle. The performance of system is determined by the rapidity and the accuracy. The drawing of soft ware block diagram and the writing of the soft ware have been finished in this paper.At last the system is debugged and the rationality of the project is proved.