Yang Guijie

Rotor Position Estimation for PMSM Based on Sliding Mode Observer

Most methods to estimate the rotor position of permanent magnetic synchronous motor (PMSM) suffer from the motor parameters, which are difficult to be applied due to the complicated algorithm. This paper presents a sliding mode observer (SMO) to estimate the rotor position of PMSM. The SMO makes use of the error between the estimated current and measured current. And the phase lag, which is caused by the low pass filter, is compensated in a proper way. The convergence of the SMO is guaranteed. A novel estimated speed is used to improve the systematic stability. High performance sensorless drive of the PMSM based on SMO is established and the whole system is simulated by matlab. Simulations show the effect of variation of the torque and speed on the estimated rotor angle. From these experiments, it is found that this method is more robust and easier to be applied.

Error analysis and compensation for inductosyn-based position measuring system

The measurement errors are incurred by the nonideal signal of an inductosyn and a digital resolver-to-digital conversion (RDC) are analyzed, and the corresponding expressions of measurement errors are determined. A compensation method by software is presented to reduce the influences of quadrature error, amplitude imbalance and signal offsets. Experimental results show that the measurement accuracy is improved significantly from 55 to 10 mechanical angle second. The correctness of the analysis and the effectiveness of the compensation are also verified.

Calculation and analysis of 3D magnetic field for end region of large turbogenerators

In order to estimate the losses and temperature rise at the end of electrical machines, it gets more and more important to make detailed calculation on end region magnetic field of large turbogenerators. The magnetic field distribution in end region of a large generator is complicated. It is necessary to adopt 3D FEM. To investigate into the clamping bolts failure of a generator, a computation on 210 MW turbogenerator is made, where load magnetic field in end region is analyzed directly with software FLUX in two scalar potential in this paper. The field domain not only consists of pressing plate, clamping bolts and stator and rotor windings, but also parts of stator and rotor core in the end. The operational conditions for calculation mainly include no load, rated load with stator end winding at 30deg and 31.5deg conical angle. Comparison of calculated results and measured results are made in a turbogenerator of Qinghe power station

Four-dimension current vector control for dual three-phase PMSM

There is only current closed loop control in the α-β subspace which is related to electromechanical energy conversion in the two-dimension current control for dual three-phase PMSM, due to the effect of voltage source inverter (VSI) dead-time and the other nonlinear factors, the phase voltage contain lower order harmonics, the harmonic impedance in the z1-z2 subspace is only comprised of the stator resistance and leakage inductance, low level harmonic voltage can induce very high harmonic currents. The harmonic currents can be suppressed by the proposed four-dimension current vector control scheme in this paper. The three-phase decomposition SVPWM is improved for four-dimension current vector control. The voltage modulation range of four-dimensional current vector control is analyzed. The effectiveness and validity of the proposed scheme are confirmed by the experiment results.