Chengzhi Cao

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A novel scheme for direct torque control (DTC) using particle swarm optimization (PSO) was proposed. The PSO was used to adjust the parameters (Kp, Ki, Kd) of PID controller. The scheme improves the adjustive capability of PID controller. PSO-PID controller decreases the torque ripple and rotor speed ripple, and increases system rapidity and stability.(More)
To improve the performance of extra-low speed in direct torque control (DTC) system, this paper applies wavelet neural network (WNN) to constitute flux observer by deep researching nonlinear mathematic model of stator flux of asynchronous motor. Furthermore, in order to improve rapidity and real time characteristics of wavelet neural network flux observer,(More)
Introducing the rank-weight method into the basic ant colony optimization (ACO), we use the modified ACO to optimize the weights and thresholds value of neural networks (NN). And when the BPNN is being trained, this method can solve the disadvantages of running into the minimum easily, and enhance the convergence speed. So we get a heuristic method, which(More)
To enhance its global optimization speed, the basic ant colony optimization (ACO) is modified, then it is used to optimize the neural networks (NN), and the optimized NN is applied to the direct torque control (DTC) system, so that the rotate speed can be observed. The DTC with speed sensorless is implemented at last. The research of simulation shows that,(More)
Based on the nonlinearity in direct torque control (DTC) system, a modified PSO (particle swarm optimization) algorithm is proposed to optimize BP (back-propagation) neural network and structure the rotational speed identifier. Combined a linear digression method of inertia weight with a particle turning laws, this algorithm can accelerate the convergence(More)
According to the non-linear relationship of direct torque control (DTC) system, multiorbit chaos optimizing algorithm is put forward, which resolve the slower converging problem of single-orbit and single-non-linearity-function chaos algorithm. In addition, the conception of neural network group (NNG) is proposed to resolve the bigger periodical errors(More)
To solve the strong randomicity and slow convergence of the Particle Swarm Optimization(PSO) algorithms, two new particle’s position renewal formulas were analyzed on the basis of extrapolation in mathematics. A new modified PSO algorithms (called Leading PSO algorithms) was put forward. The Direct Torque Control(DTC) System was built in the environment of(More)
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