An elevator group control system with a self-tuning fuzzy logic group controller

This paper presents a new group controller's adaptation mechanism with fuzzy logic for elevator group control system (EGCS) applications. Instead of depending heavily on the predicted passenger traffic pattern for adaptation, the fuzzy logic group controller (FLGC) adjusts itself to suit the system's environment through a self-tuning scheme. The average-waiting-time data that reflect the measured performance results of the EGCS are exploited to tune the membership functions of the input parameters and to modify the fuzzy rule sets employed by the FLGC, thus leading to better controller's performance and improved EGCS service quality. Computer simulation shows satisfactory improvements made in passenger waiting time and passenger riding time as compared to the performance of the conventional group controllers in three traffic peaks. The hardware implementation of the self-tuning FLGC on a TMS320C6416T digital signal processor further demonstrates its practicality

Variation in photosynthetic characteristics along the leaf blade of Oncidium Goldiana, a C3 tropical epiphytic orchid hybrid

10.1086/297528International Journal of Plant Sciences1591116-120IPLS

Comparison of basic direct torque control designs for permanent magnet synchronous motor

Basic PMSM-DTC drive controller consists of flux and torque hysteresis comparators and switching table. In the literature, three different designs have been reported. This paper investigates the three designs and compares their performance. The study aims to trace the reasons behind the recommendation of avoiding zero voltage states for PMSM-DTC reported in some studies. The system which avoids the zero states is compared with two systems include the zero states in their switching tables. The three systems are compared in their response time, switching losses, torque and flux ripples with three different input commands. The results as well as the theoretical discussion, show that the zero states should not be excluded from the switching table. The study concludes that the two level torque comparator, eight-state table design is suitable for two quadrant drives, while the three-level comparator, eight-state table is the most suitable for the four-quadrant drives

An improved two-motor three-phase drive using FCS-MPC based flux and torque control with voltage constraint consideration

This paper presents a flux and torque control scheme, based on finite-control-set model predictive control (FCS-MPC), for two three-phase induction motors supplied by a five-leg two-level inverter. The reduced-switch-count topology with leg sharing inherently imposes an additional constraint on the voltages in the system. In the best available PWM-based control scheme for this topology, the constraint means that, in simple terms, the sum of speeds of two machines cannot exceed the rated speed of one machine, in order to avoid over-modulation and large torque oscillations. In essence, no provision exists to account for the additional voltage limit of the topology. It will be shown here that the FCS-MPC can consider the voltage constraint dynamically in the control loop, and hence, apart from preserving the independent control of the two machines, it can significantly widen the speed operating range. Three different cost functions, corresponding to three operating modes, are considered. The unique way in which the MPC handles tracking errors allows the motors to operate dynamically in the base speed region with field weakening, without requiring any external change of the flux references. Simulation and preliminary experimental results verify the theory

Experimental evaluation of model predictive current control of a five-phase induction motor using all switching states

This paper presents a flux and torque control scheme, based on finite-control-set model predictive control (FCS-MPC), for two three-phase induction motors supplied by a five-leg two-level inverter. The reduced-switch-count topology with leg sharing inherently imposes an additional constraint on the voltages in the system. In the best available PWM-based control scheme for this topology, the constraint means that, in simple terms, the sum of speeds of two machines cannot exceed the rated speed of one machine, in order to avoid over-modulation and large torque oscillations. In essence, no provision exists to account for the additional voltage limit of the topology. It will be shown here that the FCS-MPC can consider the voltage constraint dynamically in the control loop, and hence, apart from preserving the independent control of the two machines, it can significantly widen the speed operating range. Three different cost functions, corresponding to three operating modes, are considered. The unique way in which the MPC handles tracking errors allows the motors to operate dynamically in the base speed region with field weakening, without requiring any external change of the flux references. Simulation and preliminary experimental results verify the theory

Design and numerical study of the integration of omnidirectional shroud with vertical axis wind turbine

The integration of a vertical axis wind turbine (VAWT) with the novel omni-directional shroud is proposed. It consists of the upper wall, lower wall and an array of 5 guide-vanes. Wind from all directions is collected radially from a larger area and the geometry of omni-directional shroud creates a venturi effect to increase the wind speed before entering the wind turbine. Guide-vanes aid to channel wind to better angles-of-attack of the turbine blades. Hence, self-starting behavior of the VAWT and the coefficient of power improve. The system was investigated numerically by simulating the wind flow over the omni-directional shroud with a single bladed NACA 0015 airfoil VAWT. In this 2D simulation, the shear stress transport (SST) k-Ȧ turbulence model with the sliding mesh method was used with the tip speed ratio of 5.1 for the wind turbine. The result was verified by re-simulating the experiment published by the Sandia National Laboratories. The result shows that the torque coefficient of the VAWT was increased up to 287% as compared to the bare VAWT. This system improves the performance of the VAWT and it has a great potential to be sited in urban areas for onsite and grid-connected power generation.University of Malaya for the research grant allocated to further develop this design under High Impact Research Grant (D000022-16001). Sincere gratitude is also dedicated to the Malaysian Ministry of Higher Education (MOHE) for Fundamental Research Grant Scheme (FP053-2013B) assigned for this project.Scopu