Zhang Xizheng

Doubly sliding mode based sensorless robust control of PMSM

An robust control scheme on the model of surface permanent magnet synchronous motor, composing a sliding-mode controller and a sliding-mode observer, was presented in this paper. To eliminate the effects of parameters variation and uncertainties, the controller was constructed instead of conventional PI controller as well as the self-adaptive rule was deduced using Lyapunov stability theory. The required voltage and current for the desired speed was then solved. A sliding-mode observer was employed to estimate the rotor position and speed. The convergence condition and controlling rule for the estimated algorithm was also obtained by utilizing Lyapunov theory. Theoretical analyse proved the independence of parameters variation and uncertainties and showed the good robustness of the scheme. Computer simulations and the realization were done and results testified the effectiveness and correction of the proposed scheme.

Efficient broadcast scheduling based on hybrid fuzzy hopfield network for Ad hoc networks

Due to the mutual interference and sharing of wireless links in TDMA Ad hoc networks, conflicts will occur when data message are transmitting between nodes. The broadcast scheduling problem (BSP) is aim to schedule each node in different slot of fixed length frame at least once, and the objective of BSP is to seek for the optimal feasible solution, which has the shortest length of frame slots as well as the maximum node transmission. In this paper, we propose a two stage hybrid algorithm based on fuzzy Hopfield neural network to solve this BSP in Ad hoc. In the first stage, we use a modified sequential vertex coloring algorithm to obtain a minimal TDMA frame length. Experimental results, obtained from the running on three benchmark graph, show that our algorithm can achieve better performance with shorter frame length and higher channel utilizing ratio than other exit BSP solutions.