Modeling and Simulation of High-Voltage Asynchronous Motor Voltage-Regulator

For starting high-voltage asynchronous motor,the voltage regulator based on current-limiting transformer is presented in the paper. Its mathematical model needs to be established analyzing and designing voltage regulator of high-voltage asynchronous motor. The mathematical model of the current-limiting transformer is deduced based on basic circuit theory. It can be found that a continuous variation reactance can describe the current-limiting transformer during starting process. The two variables functions of current and voltage are transformed into one-variable functions,and thus system control is greatly simplified. The voltage regulator is simulated on the basis. The simulation results show that this model has enough accuracy. Finally, the high-voltage asynchronous motor voltage regulator based on current-limiting transformer is designed and tested on this model.

Comprehensive Energy-Saving Optimization Model of Asynchronous Motor for Voltage Regulation Based on Static Synchronous Compensator

There are several problems existing in the direct starting of asynchronous motor such as large starting current,reactive power absorption from network side and weak interference-resistance,etc.Aiming at this,a comprehensive energy-saving optimization model of asynchronous motor for voltage regulation based on static synchronous compensator(STATCOM)is put forward.By analyzing the working principle and operation performance of static synchronous compensator regulating voltage,a new energy-efficient optimization method for asynchronous motor is proposed based on the voltage regulator model to achieve soft start,continuous dynamic reactive power compensation and the terminal voltage stability control.The multi-objective optimal operation of asynchronous motor is realized by controlling the inverter to adjust the reactive current dynamically.The strategy reduces the influence of starting current and grid voltage by soft starting,and realizes the function of reactive power compensation and terminal voltage stabilization.The effectiveness and superiority of the proposed model is verified by the simulation analysis and the results of comparison with the motor started directly.

Comparison between PI-DTC-SPWM and fuzzy logic for a sensorless asynchronous motor drive

Currently, asynchronous cage motors are among the most commonly requested machines accentuated by their extension to the field of electric vehicles. Therefore, the development of robust and sophisticated controls for this machine is of significant interest. Artificial intelligence control techniques, such as fuzzy logic, are at the forefront of recent research. However, their design becomes much more complicated for a motor via a multilevel inverter. The main purpose of this paper is to show that it is possible to achieve fuzzy logic control of a squirrel cage asynchronous motor supplied via the usual two-level inverter. This is achieved, by adopting a DTC strategy based on a sinusoidal PWM with multilevel inverter. It employs a feedback information estimator with dual structure between the sliding mode observer at low speed and the model reference adaptive system in sliding mode at high speed. For both installations, speed is regulated using a sliding mode controller.

Sliding mode approach applied to sensorless direct torque control of cage asynchronous motor via multi-level inverter

To improve the robustness and performance of the dynamic response of a cage asynchronous motor,a direct torque control(DTC)based on sliding mode control(SMC)is adopted to replace traditional proportional-integral(PI)and hysteresis comparators.The combination of the proposed strategy with sinusoidal pulse width modulation(SPWM)applied to a three-level neutral point clamped(NPC)inverter brings many advantages such as a reduction in harmonics,and precise and rapid tracking of the references.Simulations are performed for a three-level inverter with SM-DTC,a two-level inverter with SM-DTC and the three-level inverter with PI-DTC-SPWM.The results show that the SM-DTC method achieves better performance in terms of reference tracking,while adoption of the threelevel inverter topology can effectively reduce the ripples.Applying the SM-DTC to the three-level inverter presents the best solution for achieving efficient and robust control.In addition,the use of a sliding mode speed estimator eliminates the mechanical sensor and this increases the reliability of the system.

Interroll tension model adapted to a secondary annealing process

Due to the special secondary rolling and annealing processes,the physical properties of strip ductility and stress relief differ from those of the general products.The proportional integral differential(PID)algorithm for the annealing furnace tension control and the conventional control method that only controls the total tension of the furnace entrance and exit cannot meet production continuity.Aiming at the tension in the annealing furnace,the interroll tension model of the tension of the steel strip between the adjacent furnace rolls is established.By combining the control principle of the annealing furnace roll transmission mechanism,the tension control involves the motor and frequency converter equipment.The coupling relationship between the stator current and the motor’s output torque was determined through the asynchronous equivalent motor circuit.Also,the direct influence of the load torque on the calculated value of the motor’s output tension was obtained through the motor vector control equation.Furthermore,the frequency converter’s voltage control model was analyzed to control the motor’s output tension.Finally,the adjacent furnace roll tension and the horizontal annealing furnace tension were calculated through the interroll tension model.