Jianhu Yan

Analysis of a Novel Switched-Flux Memory Motor Employing a Time-Divisional Magnetization Strategy

This paper presents a novel switched-flux memory motor (SFMM) by artfully incorporating the flux-mnemonic concept into the conventional switched-flux permanent magnet machine. The magnetic susceptibility of AlNiCo PM provides the flexible online controllability of air-gap flux by imposing a transient current pulse. To uniformize magnetization levels of PMs, a time-divisional magnetization strategy (TDMS) is proposed. Due to the uniqueness of hysteresis nonlinearity and instability regarding AlNiCo PM operating point, the time-stepping finite element method (TSFEM) dynamically coupled with a nonlinearity-involved parallelogram hysteresis model (NIPHM) of AlNiCo PM is performed to investigate the electromagnetic performance of the proposed SFMM. The results derived from the combinative algorithm verifies the flux-adjustable capability of the proposed motor equipped with TDMS and the validity of the proposed NIPHM.

Magnetic field analysis of a novel flux switching transverse flux permanent magnet wind generator with 3-D FEM

Transverse flux permanent magnet machine (TFPMM) offers a higher power density than the conventional radial and axial ones. Based on the principle of TFPMM, a novel flux switching transverse flux PM generator (FS-TFPMG) with a unique structure is presented for low speed wind power applications in this paper. The stator space utilization can be improved by arranging more stator cores and the flux density in air-gap can be gathered up by adopting a novel topology. The structure and principle of the proposed FS-TFPMG are described in detail. The magnetic field of a FS-TFPMG with six pole pairs is numerically computed by three-dimensional (3-D) finite element method (FEM). The primary characteristics of the generator, including no-load EMF and flux waveforms and inductance of winding are numerically analyzed.

A novel energy feedback control method of flywheel energy storage system based on radial basis function neural network

A novel energy feedback control method based on radial basis function neural network (RBFNN) for flywheel energy storage system (FESS) driven by brushless DC motor (BLDCM) is proposed and applied in a wind power conversion. The RBFNN is trained off-line by adding new hidden neurons in the process of learning. Compared with the traditional PID controller, the proposed method can further reduce the ripple of DC bus voltage to improve the stability of output power when wind speed changes, which enhances the reliability and safety of the power system. A stand-alone wind energy generation system including a FESS driven by a BLDCM is simulated by Matlab/Simulink. The simulation results verify the effectiveness and correctness of the proposed method.

Analytical modeling of air-gap field distributions in permanent magnet embedded salient pole wind generator

A simple magnetic circuit method (MCM) is developed for analytical calculation of the air-gap magnetic flux density waveform of a permanent magnet embedded salient pole wind generator (PMESPWG), which can consider the saturation in the side frame and the upper core of its pole shoe. In the MCM, the magnetic circuit is divided into a series of sub-circuits according to the flux paths to cope with different lengths of air-gap and different saturation levels of the pole shoe upper core. In order to evaluate the validity of the proposed method, air-gap flux densities of a 3.3 MW machine prototype are calculated and validated by the finite-element method (FEM) results. By utilizing the developed MCM, the air-gap flux distribution of the PMESPWG is optimized to obtain the maximum fundamental and minimum total harmonic distortion.

Design and analysis of a novel permanent magnet embedded salient pole for wind generator

This paper presents a design and analysis of a novel permanent magnet embedded salient pole (PMESP) for PM synchronous wind generator (PMSWG). A lumped parameter magnetic circuit model (LPMCM) of the salient pole is established to design its main dimensions. The magnetic field distribution, electromagnetic performance and external characteristic of a 3MW generator with PMESP are analyzed by the finite element method (FEM). The air gap flux variations with pole edge width are investigated especially to make PMESP have less leakage flux and sufficient mechanical strength.

Speed estimation with sliding mode model reference adaptive system for PM generator in direct drive wind conversion system

This paper presents a sliding mode model reference adaptive system (SM-MRAS) to estimate the speed of permanent magnet generator (PMG) in direct drive wind conversion system (DDWCS). Compared with the speed sensor system, the DDWCS with a SM-MRAS features higher reliability. Using the proposed SM-MRAS, a speed sensorless DDWCS is developed, in which the maximum power extraction (MPE) of wind power is realized through a back-to-back controllable full power converter by using SVPWM control method. The simulation and experiment of a speed sensorless DDWCS with a 750W PMG are carried out to verify the correctness and effectiveness of the proposed SM-MRAS.

Simulation of wind power system involving flywheel energy storage unit based on wind speed forecasting by RBF neural network

A wind power system (WPS) involving a flywheel energy storage (FES) unit is proposed to reduce the fluctuation of output power due to the intermittent nature of wind power. The control of the FES unit is based on a wind speed forecasting technique by the RBF neural network. A new control strategy adopting different reference DC bus voltages under different forecasting wind speeds is presented to improve the output power regulation capability of the FES unit. The wind speeds in the next time array can be accurately forecasted by the radical basis function (RBF) neural network. The mathematical model of a stand-alone wind power generation system including a FES unit is established and simulated by Matlab/Simulink. The simulation results verify the correctness of the system model and the effectiveness of the control method.