Research On Excitation Principle And Control Technology Of Harmonic-current-excited Brushless Synchronous Machine

The permanent magnet synchronous motors(PMSM),which are widely used currently,generally require rare earth permanent magnet materials to manufacture.As the price of rare earth permanent magnet material was unstable,and common electrically excited synchronous motors require extra slip rings and brushes or exciters,which makes the motor more complex and less reliable.The paper proposed a type of brushless synchronous motor with open windings,which was excited by harmonic current.This type of electrically excited synchronous motor can work without extra exciters,which is of great theoretical research value.The paper studied the brushless harmonic current excited synchronous motor,including: the calculation of the excitation process;the control and starting method;improvement project for the starting ability improvement;simulation of theoretical analysis;experiments on related hardware.The paper calculated the generating principle of exciting current.The magnetomotive force and the induced voltage in the rotor windings were calculated when the stator windings contained different kinds of currents.The influence made by stator slots was analyzed.The exciting current was calculated when the motor was at rest,and the influence of different initial rotor positions was analyzed.The validity of the calculation was verified using software by simulating the induced voltage and exciting current produced by different kinds of stator currents.Control and start methods were analyzed.The mathematical model and control system model was founded to simulate the control and starting method.The results of the simulation verified the feasibility of control method.The starting ability of the motor with different rotor positions was also analyzed.The paper also proposed an improved type of brushless synchronous motor which could start up with any rotor positions.The stator winding of this type of brushless synchronous motor is a double three-phase winding.The differences between two types of motor in excitation principle and control method were analyzed.The validity of calculation was verified using simulation software.Finally,the hardware experiment platform was built to improve the research on excitation principle and control method of the motor.The induced voltages produced by different kinds of stator currents were recorded.The idle state and rotating state of the motor were both detected.The starting experiment of the motor was also carried out.