Kangling Fang

A scheme of fuzzy direct torque control for induction machine

In this paper, a novel fuzzy logic direct torque control (FLDTC) scheme combining with space voltage modulation (SVM) technique is presented. Using fuzzy logic technique, the reference space voltage vector can be obtained dynamically in terms of torque error, stator flux error and the angle of stator flux. Compared with conventional direct torque control (DTC), this scheme is easily implemented for induction machine, the ripples of both torque and flux are reduced remarkable, and switching frequency is maintained constant. Simulation results verify the validity of the proposed method.

A Fuzzy Control Algorithm for Collecting Main Pressure Controlling Using Expert Control

The disturbance, multi-parameters, and non-linearities are the major difficulties in the collecting main pressures control system. This paper develops a fuzzy control algorithm for the collecting main pressure control based on expert control, in order to solve the collecting main pressure disturbance problem. The fuzzy algorithm adopts two phase control strategies. One is the fuzzy feed-forward control algorithm for decoupling control. Another is the expert control algorithm for the cooler actuating power control. The experience results show the fuzzy control algorithm using expert control can make collecting main pressure and the cooler actuating power in the requirement range and obtain a well control performance.

Fuzzy decoupling adjustment for the pressure of coke oven collecting main

In order to resolve the coupling phenomena in the collecting main pressure system, a fuzzy decoupling method with the idea of feed-forward control is presented to reduce the coupling phenomena of collecting main in this paper, and good effect has been attained in practical application.

A Genetic Programming Based Fuzzy Model for Fault Diagnosis of Power Transformers

In this paper, a fuzzy model based on genetic programming (GPFM) is proposed to diagnose the fault types of insulation of power transformers. The proposed GPFM algorithm constructs the fuzzy relationship between input and output fuzzy variables by genetic programming algorithms. The parameters of memberships of fuzzy subsets and the fuzzy relationship of system are represented by the GP candidates that have the form of tree-like combinations of fuzzy subsets of input variables. Then the best fuzzy function is evolved by genetic operations and evolution. Based on the proposed GPFM algorithms, an insulation fault diagnosis system for power systems is designed to distinguish the insulation fault types of power transformers. Compared with the conditional fuzzy IEC code method, the GPFM algorithm can automatically generate fuzzy relationship between fault symptom with fault types and shows better performances.

A HGA based on the analysis of best value region and application to the fuzzy controller

A hybrid genetic algorithm (HGA) based on analysis of best value region, according to the concept of population Hamming-distance, is proposed. This HGA is applied to the optimization of the fuzzy controller in the temperature control of an industrial stove. The result of practical operation shows that the fuzzy control system with HGA has a better static and dynamic characteristics.

Multi-model Generalized Predictive Control for Temperature Control System

A multi-model control algorithm based on T-S model is presented in this paper. A stable generalized predictive controller is constructed as a local controller for the linear model, which constitutes the consequent of each fuzzy rule in the T-S model. The stability proof is given for the local controller, and then the global controller is implemented by weighed integration of the local controller. The proposed algorithm is applied to a temperature control system and the experimental results demonstrate the merits and effectiveness of the new algorithm.

Direct torque control for dual three phase induction machine using fuzzy space voltage modulation

Conventional hysteresis control schemes for direct torque control (DTC) of dual-three-phase induction machine (DTPIM) usually result highly distorted current waveforms. In this paper, fuzzy space voltage modulation technique is presented for DTPIM. Using two fuzzy controllers, amplitude and space angle of desired stator voltage vector, are obtained dynamically. Combined with unified pulse width modulation method, direct torque control is applied to DTPIM. Simulation results show that fast dynamic responses are achieved. The ripple of torque and the harmonics of stator current in steady state can be reduced remarkably compared with conventional DTC method.

A fuzzy predictive control algorithm based on discrete optimization and its application to nonlinear systems

A fuzzy predictive control algorithm based on fuzzy model and discrete optimization is presented for a family of complex systems with high nonlinearity. In order to implement nonlinear predictive control of the controlled plant, the T-S fuzzy predictive model is built online using fuzzy clustering and linear identification, and discrete optimization of the control action is implemented according to the principle of branch and bound method. The effectiveness and advantage of the presented algorithm are demonstrated by applying the algorithm to two nonlinear system models.

Disturbance-free operation of five-phase induction machine with one stator winding open circuited

A disturbance free operation method of five-phase induction machine with one stator winding opened is presented in this paper. The four healthy phase currents are derived by keeping stator magnetomotive force unchanged when a stator winding opened. Based on symmetrical component method and equivalent circuits of five-phase induction machine, voltage of the four healthy phases, which is supply to the fault machine, is obtained. The torque and rotor speed are not changed remarkably, and the currents of four healthy phases are controlled in balance. The presented method is verified by simulation results.

Direct torque control for dual-three phase induction machine with one stator phase opened

A direct torque control (DTC) strategy for dual-three phase induction machine with one stator winding open-circuited is discussed in this paper. An optimums election scheme of space voltage vector is proposed based on fuzzy control and direct torque control. The largest space voltage vectors are selected to control the machine. To verify the presented method, fuzzy direct torque control of dual-three phase induction machine is simulated. The simulation results show that the machine in fault state is still effectively controlled, and good dynamic performances are obtained with the proposed method.