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In this paper, an energy-saving scheme in rotor field-orientated vector control is developed for induction motor drives. The energy-saving scheme minimizes copper and core losses in induction motors, which are equally applicable to induction generators. In efficiency optimization, an optimal stator angular velocity is uniquely obtained, and consequently, a corresponding optimal slip at any given rotor speed is determined. The challenge of determining a reference for rotor flux linkage that guarantees the minimal copper and core loss regime is overcome by developing a load torque observer loop. The torque observer is developed alongside a rotor speed observer for a sensorless speed operation. The observed mechanical torque is further used to enhance the outer-loop rotor speed control that generates an electromagnetic torque command used in building the reference for the inner-loop stator current control. The results obtained justified the effective operation of the torque and rotor speed observer, which consequently verified the effective minimal electrical loss regime at the optimal stator angular velocity and optimal rotor flux linkage. The results are further compared to results obtained from the equivalent induction machine drive on a finite-set model predictive control (FS-MPC) scheme with the same values of the optimal stator angular velocity and optimal rotor flux linkage. The developed efficiency-optimized vector control scheme gave lower ripples in developed electromagnetic torque and dampened overshoot better during step change in load torque. [ABSTRACT FROM AUTHOR]

The paper presents an improvement in estimating the rotor flux angle using the voltage model of the field-oriented control (FOC) technique in the induction motor speed control. The voltage model uses the inputs including the stator voltage and current signals to estimate the rotor flux angle for FOC method. However, the inaccuracy of the stator resistance value can affect the estimation of the rotor flux angle, leading to a decline in the performance of the control method. An adaptive tuning method based on the machine model is used to estimate the stator resistance to enhance the accuracy of the rotor flux angle in the FOC method. Simulations of the induction motor drive (IMD) operating in the case of stator resistance changing will be performed to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, an energy-saving scheme in rotor field-orientated vector control is developed for induction motor drives. The energy-saving scheme minimizes copper and core losses in induction motors, which are equally applicable to induction generators. In efficiency optimization, an optimal stator angular velocity is uniquely obtained, and consequently, a corresponding optimal slip at any given rotor speed is determined. The challenge of determining a reference for rotor flux linkage that guarantees the minimal copper and core loss regime is overcome by developing a load torque observer loop. The torque observer is developed alongside a rotor speed observer for a sensorless speed operation. The observed mechanical torque is further used to enhance the outer-loop rotor speed control that generates an electromagnetic torque command used in building the reference for the inner-loop stator current control. The results obtained justified the effective operation of the torque and rotor speed observer, which consequently verified the effective minimal electrical loss regime at the optimal stator angular velocity and optimal rotor flux linkage. The results are further compared to results obtained from the equivalent induction machine drive on a finite-set model predictive control (FS-MPC) scheme with the same values of the optimal stator angular velocity and optimal rotor flux linkage. The developed efficiency-optimized vector control scheme gave lower ripples in developed electromagnetic torque and dampened overshoot better during step change in load torque.

Traditional rotor flux observers cannot accurately estimate rotor flux due to influence of DC disturbance and harmonic disturbance, and then sensorless control method of permanent magnet synchronous motor(PMSM) based on rotor flux cannot accurately estimate rotor position. In order to solve the above problem, a sensorless control strategy for PMSM of scraper conveyor based on third-order generalized integral flux observer(TOGIFO) was proposed. By introducing the TOGIFO, high-order harmonic component can be effectively suppressed, and DC component in rotor flux can be completely eliminated in steady state without amplitude attenuation and phase delay of fundamental wave, so as to accurately estimate rotor flux and improve accuracy of rotor position estimation. The simulation results verify correctness and effectiveness of the control strategy.

The control parameters of traditional PID controller applied in the mine hoist frequency conversion speed control system is fixed and difficult to be set, which aeaks leads to large speed overshoot and ripples of the electromagnetic torque and rotor flux linkage. In order to improve the performance of the system, an improved particle swarm optimization BP neural network PID controller algorithm of hoist rotor frequency conversion speed regulation system is proposed in the present study. The application of particle swarm algorithm which has fast convergence speed and global optimal characteristics in neural network can overcome the disadvantages of slow convergence speed and easy to fall into local optimum of BP neural network. In addition, the neural network convergence coefficient is designed to further accelerate the convergence speed. The simulation results show that the neural network control effect of particle swarm optimization is better than the neural network, and the effect is obviously better than the traditional PID controller. Compared with the neural network PID controller, the steady speed adjustment speed of the mine hoist speed regulation system of particle swarm optimization is obviously improved. Compared with the traditional PID controller, the ripple of the electromagnetic torque and rotor flux of the motor are significantly reduced, which has strong stability and robustness. [ABSTRACT FROM AUTHOR]

This work presents a novel stator flux‐oriented vector control (SFOVC) of a dual stator induction generator (DSIG) used for a grid connected, variable speed wind energy generation system. The DSIG consists of two stator windings electrically separated by an angle of 30° with dissimilar pole numbers, which are in the ratio of 1:3. In conventional vector control, the rotor flux is oriented along the d‐axis of the rotor winding. However, the rotor variables are not easily accessible. So, in the SFOVC, the total flux is made to be oriented along the d‐axis of the stator winding. SFOVC is advantageous as compared to conventional vector control because the stator variables are easily accessible and do not require any special arrangement for the measurement of variables which increases the robustness of the system. Here, two separate converters are used for the two stator windings of the machine and the converter switching is being controlled by a novel space vector based 11‐zone hybrid pulse‐width modulation (PWM). This special PWM results in better harmonic performance, reduced torque pulsation and minimal switching loss. The overall simulation is being performed in MATLAB Simulink environment and the simulated results are also being validated experimentally. [ABSTRACT FROM AUTHOR]

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Summary: This work investigates the effect of voltage unbalance on the starting and steady‐state performances of squirrel cage induction motors. Emphasis is placed on the rotor flux and slip. Both copper losses accumulated during the run up and at steady state are investigated. Five motor ratings of up to 4000 kVA operating at partial and at full load are studied. Because the same voltage unbalance factor may result in different behaviors, a voltage code is proposed to simplify referring to the individual per unit phase magnitudes. Full load operation at a voltage unbalance factor higher than 3.5% showed an increase of copper losses of more than 50%. Voltage unbalance cases that fail to pull up the motor to at least 50% of the rated speed show rotor fluxes too low to generate the required torque. [ABSTRACT FROM AUTHOR]

An appropriate and complete mathematical modelling approach is developed for an interior permanent magnet synchronous motor (PMSM) with general eccentricity. The relationships between air‐gap eccentricity and simulated inductances in different coordinate frames are analysed in depth. Then, an analytical high‐frequency inductance model of the interior PMSM with rotor eccentricity is developed. Based on this model, an online diagnostic approach is proposed, which includes estimation of the high‐frequency d‐axis inductance and permanent magnet (PM) flux. Thus the rotor eccentricity and PM partial demagnetisation can be detected and distinguished. Experimental results validate the proposed theory and fault diagnosis approach. Finally, an effective and reliable eccentricity indicator is presented. It is shown that analysis of the essential sources of fault characteristics facilitates motor fault diagnosis. [ABSTRACT FROM AUTHOR]