Chen Yaai

A novel fuzzy logic controller for indirect vector control induction motor drive

This paper presents a novel fuzzy logic controller (FLC) for indirect vector control induction motor (IM) drive. The fuzzy logic speed controller is used in the speed loop. The 4 kW three-phase squirrel cage IM is fed by a current controlled voltage source inverter (CCVSI). The complete vector control scheme of the IM drive is implemented in real time using TMS320LF2812 digital signal processor. The simulation and experiments are carried out for the proposed drive system. The simulation model of the drive system is developed in MATLAB environment to analyze the performances of the novel IM drive system. The experimental results verify that the proposed FLC can not only enhance the robustness of the system, but also improve the steady-state precision and dynamic performances.

Research on the fault characteristics and fault diagnosis methods of three-level high-power inverter

As one kind of multilevel inverters, three-level inverter is widely used in the high-power and high-voltage applications. However, the increasing of the power devices improves the systems fault rate. How to ensure stable operation of the system has become an important research question. Through theoretical analysis and simulation on three-level high-power inverter, the paper analyses the working situation of the power devices of main circuit under the open-circuit fault, the specific fault characteristics and the typical waveform in detail, and sums up the rules of fault diagnosis. Finally, based on the three-level high-power inverter, the open-circuit fault experiment of power devices is carried out .The experimental results further validate the fault analysis and simulation results of the power devices.

Research on the control strategy of PV grid-connected inverter upon grid fault

To stabilize the PV-connected grid with high penetration factor, the State formulates strict provisions on connecting the PV power stations into the power grid to ensure the safety of power system. On the basis of high-power PV power station LVRT technology, this paper elaborates the research on solving the inverter protection upon low-voltage operation by means of the control strategy under conditions of not adding other hardware to fulfill the safe ride through in the low-voltage zone, and to provide the power grid with reactive support, so as to help the recovery of grid system.

Reducing voltage energy-saving control method of induction motor

The paper starts from the angle of the induction motor energy loss, antis light-load energy conservation issues for induction motor, proposes a closed-loop control method of the motor power factor which is the amount of system feedback, and gives the constraint condition of the reducing voltage energy-saving. Different loads have different values of the optimal motor power factor, real-time adjusting the motor power factor to make the motor always run at the optimal power factor, and when running at light load, reducing the output voltage of the inverter, to reduce the motor copper loss and iron loss, to improve motor efficiency and power factor, to achieve reducing voltage energy-saving purposes, and to achieve the function of induction motor load following energy-saving. The experimental results show that the motor is able to maintain a high power factor operation in light load conditions, and has a good energy-saving effect.

Development of digital experiment system for multi-module-cascaded multilevel high-power inverter

Based on a multi-module-cascaded multilevel inverter structure for the optimization of harmonics, this paper introduces a horizontal phase-shifting sinusoidal pulse width modulation (SPWM) strategy applied to multi-module-cascaded inverter, and at the same time, based on Digital Signal Processor (DSP) and Complex Programmable Logic Device (CPLD), this paper also presents a digital algorithm for horizontal phase-shifting SPWM modulation, which has solved the problem of the exactly lock of each triangular carrier phase in the multi-module-cascaded system. The simulation and experimental results have proven the method proposed correct.

Torque control method of permanent magnet synchronous motor based on Lyaponov theory

This study presents a novel means of designing a simple torque controller for Permanent Magnet Synchronous Motor (PMSM): a Lyapunov technique approach. The overall stability of the system is shown using Lyapunov technique. The Lyapunov functions used contain a term penalizing the integral of the tracking error, enhancing the stability. The tracking error is shown to be globally uniformly bounded. Simulation results are presented to show the effectiveness of the approach.