Adjustable magnetic gear

Abstract

A mathematical interpretation of a combined electromechanical device possessing the properties of a synchronous machine connected to a frequency converter and of a magnetic gear with a variable reduction factor is considered. The stator winding of the synchronous machine is concentrated (tooth winding), and its spatial period covers the full number of teeth z. An expression for the frequency response of the magnetomotive force (MMF) of the tooth winding was obtained. In the variant under consideration (z = 36), the fundamental harmonic of the magnetic field, which sets the number of stator pole pairs, is v = p = 17. The MMF of the magnets of the internal rotor is represented as a Fourier series. Formulas are given making it possible to calculate the magnetic fields in two air gaps of the magnetic gear caused by the stator current and magnets of a high-speed rotor (using the method of specific magnetic conductivity). The electromagnetic torques of the gear shafts are calculated by the stretch method. The electromagnetic torque caused by the stator winding is determined on the basis of the instantaneous values of the EMF of rotation and transformation of each winding coil without using the winding coefficients. A differential equation system for calculating the transient processes in three channels of a wind-power plant is obtained: in two mechanical channels and in one electrical channel. A closed system with a PID controller is proposed making it possible to stabilize the rotational speed of the electric generator of a wind-power plant with a variable wind speed.