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This paper presents digital simulation of variable frequency transformer (VFT). The variable frequency transformer (VFT) is a device which produces desired voltage and frequency supply for constant and variable V/f control of ac drive. The main parts of VFT is a rotary transformer with three-phase windings on both stator and rotor. A controlled drive system is mechanically coupled with the VFT, to...
Doubly-fed induction generators (DFIG) are widely used in the wind farms. Many papers focus on their behavior connecting to an infinite bus and the influence on the power system stability ignoring the grid side converters. In this paper, the dynamic simulation of doubly-fed induction generators on multi-machine power system is studied. With the decoupled active and reactive power control scheme, compensated...
The suitability of distributed power generation systems working at medium and high capacity as it is the case of wave power generation plants, requires a reliable Fault-Ride-Through capability. When a grid fault occurs on the transmission system, the speed of the turbo-generator group increases uncontrolled, the induction generator injects large peak currents that can potentially damage the rotor...
A dynamic decoupling control approach based on inverse system theory is developed for the electric spindle system supported by 5 degree-of-freedom (DOF) AC active magnetic bearings(AMB), which is multi-variable, nonlinear and strong coupling system. The state equations of the 5-DOF AC AMB are set up based on the configuration of 5-DOF AC AMB being introduced and mathematical models of axial and radial...
In order to compare the torque performance of the three-phase induction machine with the six-phase induction machine, an experimental setup to test the torque performance has been done; Under the same condition and by using different control principle the three-phase and six-phase machines constructed for the same frame of the stator and rotor are tested. The three-phase is driven by Danfoss drive...
Present paper describes the design of a doubly fed induction generator (DFIG) test bench with active crowbar, using a PWM voltage-fed inverters connected between the grid and the rotor. A vector control scheme is proposed in order to control the power-side and the rotor- side of the converter. A control board, based on a digital signal processor (DSP) and a FPGA, has been developed to manage the overall...
A spherical stepping motor with a hexahedron based rotor and an octahedron based stator is designed. The motor has a rotor supported by six spherical bearings and a stator. Eight NdFeB permanent magnets are attached at the vertexes of the virtual hexahedron inscribed in the rotor so that the North and the South poles are located alternately. Six iron cores are also attached on the spherical shell...
This paper propose an adaptive sliding mode observer(SMO) which adds an estimation function for the stator resistance to the conventional sliding mode observer. It is proposed for the robust sensorless control of permanent magnet synchronous motor(PMSM) with variable parameters. The low-pass filter and additional position compensation of the rotor are used to reduce the chattering problem commonly...
According to the magnetic suspension character of the rotor in the new type of gyro, the control mathematic model for the gyro's rotor magnetic suspension system is founded. The system is characterized by its instability ' nonlinearity. In this paper, a variable structure controller is designed. Based on the general variable structure controller theory, the design of switch function using the method...
In this paper, stator-flux orientation control strategy for the flux-switching permanent magnet (FSPM) motor under two pulse width modulation (PWM) generation modes, namely current hysteresis and voltage space vector, is investigated and implemented. Firstly, the definition of d- and q-axes for the FSPM motor, which is crucial to the mathematic model and control strategy, is highlighted. The fundamental...
A scheme of a model reference adaptive system (MRAS) based on the theory of parameter optimization for the PMSM servo system is described in this paper. The scheme can promptly work out the speed of the rotor without any other position/speed sensor. Different from the other MRAS-based speed observers which constructed according the theory of stability customarily, by using the error between the measured...
The vibration originated from the rotor's unbalance mass impacts on the current oscillation. As the rotor rotating at high speed, Power amplifier circuit will be burned down by excessive control current. While vibrating force transfers to frame, which causes the system vibration and influence the dynamic properties and safe operation. So unbalance compensation on the rotating machine is necessary,...
The application of the slide-mode observer in the sensorless vector-control of permanent magnet synchronous motor (PMSM) is proposed. Design a slide-mode observer to estimate the information of rotor position. Establish the adaptive rule and analysis the stability of the slide-mode observer. The application of the space vector pulse width modulation (SVPWM) is introduced in the control scheme of the...
Nowadays, many efforts are made to realize the position/speed sensorless control strategy of permanent magnet synchronous motors (PMSM) to simplify the control structure and cut down the cost. A sensorless control scheme based on a model reference adaptive system (MRAS) with the theory of parameter optimization for the PMSM servo system is described in this paper. The scheme can promptly work out...
A linearized model of a self-sensing magnetic bearing used in a flywheel energy storage application is analyzed, and an intrinsic feedback mechanism is identified. Based on the model, a cascaded-loop controller is designed using a novel control design technique which actively rejects external disturbances, taking advantage of the feedback mechanism. Simulation results of force-disturbance rejection...
In this paper, a new direct torque control (DTC) strategy of the doubly fed induction machine (DFIM) is presented. It is especially designed to operate at a considerably low constant switching frequency, reducing the electromagnetic torque and rotor flux ripples, in order to provide good steady-state and fast dynamic performances, for high power drive and generator applications, with restricted switching...
In this study, the authors proposed a method of controlling harmonic parasitic torque in concentrated winding induction motor and validated its theory's practicality through the experiment. To control harmonic, the rotor was skewed at an angle and to determine optimum skew angle, three dimensional electromagnetic analysis was performed. The result of analysis demonstrated larger than 20 degree skew...
A magnetically levitated induction motor is a multivariable, nonlinear and strong coupling system. In order to achieve the rotor suspending and working steadily, it is necessary to realize dynamic decoupling control between torque force and radial suspension forces. In this paper, a method based on inverse system theory is used to study on decoupling control of magnetically levitated induction motors...
A stand alone power generation system with doubly fed induction generator and its control method is presented in the paper. A slip-ring induction generator is equipped with the stator connected capacitances for filtering the switching frequency harmonics produced by the rotor connected power electronics converter. The proposed direct voltage control method, based on the stator voltage vector reference,...
A magnetically levitated induction motor is a multivariable, nonlinear and strong coupling system. In order to achieve the rotor suspending and working steadily, it is necessary to realize dynamic decoupling control between torque force and radial suspension forces. In this paper, a method based on inverse system theory is used to study on decoupling control of magnetically levitated induction motors...
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