Field Weakening Control of a Separately Excited DC Motor Using Neural Network Optemized by Social Spider Algorithm

This paper presents the speed control of a separately excited DC motor using Neural Network (NN) controller in field weakening region. In armature control, speed controller has been used in outer loop while current controller in inner loop is used. The function of NN is to predict the field current that realizes the field weakening to drive the motor over rated speed. The parameters of NN are optimized by the Social Spider Optimization (SSO) algorithm. The system has been implemented using MATLAB/SIMULINK software. The simulation results show that the proposed method gives a good performance and is feasible to be applied instead of others conventional combined control methods.

Frequency difference lock-in phenomenon's weakening by transverse magnetic field in Y-shaped cavity dual-frequency laser

We report experimental progress in weakening the frequency difference lock-in phenomenon in a Y-shaped cavity dual-frequency laser. A cube coil pair is chosen to provide a uniform magnetic field for tunability and uniformity of magnetic field strength. When the transverse magnetic field intensity is 9 m T, the frequency difference lock-in phenomenon is evidently weakened and the frequency difference can be continuously tuned in the range of0.12 MHz to 1.15 GHz. Moreover, the relationship between the minimal frequency difference and magnetic field intensity are investigated and discussed. Then a Y-shaped cavity dual-frequency laser is expected to be utilized as an optimum light source for heterodyne interferometric sensing and precise laser measurement.

A novel MTPA and flux weakening method of stator flux oriented control of PMSM

Permanent magnet synchronous motor(PMSM)has the advantages of high efficiency,high power density and high reliability.It has been widely used in electric vehicles,rail transit,industrial transmission and other fields.Compared with the traditional PMSM control strategy,the Indirect stator-quantities control(ISC)of low torque ripple induction motor has high dynamic response performance in the whole speed range,with high stability and strong security.However,due to the inherent characteristics of PMSM,there are still some difficulties in applying ISC strategy,such as solving the load angle corresponding to the current torque,realizing the maximum torque per ampere(MTPA)control and flux weakening control method in the stator field oriented control algorithm of PMSM.In this paper,theoretical analysis and discussion are carried out for the above difficulties,and an indirect stator vector control(ISC)method for PMSM is proposed.Finally,combined with the electric drive application platform of electric vehicle,the simulation and experimental results verify that the proposed ISC control strategy of PMSM also has good dynamic and steady-state performance in the whole speed range.

Research on a direct torque control for an electrically excited synchronous motor drive with low ripple in flux and torque

The electrically excited synchronous motor(ESM)has typically small synchronous inductance values and quite low transient values because of the damper windings mounted on the rotor.Therefore,the torque and stator flux linkage ripples are high in the direct torque control(DTC)drive of the ESM with a torque and flux linkage hysteresis controller(basic DTC).A DTC scheme with space vector modulation(SVM)for the ESM was investigated in this paper.It is based on the compensation of the stator flux link-age vector error using the space vector modulation in order to decrease the torque and flux linkage ripples and produce fixed switching frequency under the principle that the torque is controlled by the torque angle in the ESM.Compared with the basic DTC,the results of the simulation and experiment show that the torque and flux linkage ripples are reduced,the maximum current value is decreased during the startup,and the current distortion is much smaller in the steady-state under the SVM-DTC.The field-weakening control is incorporated with the SVM-DTC successfully.