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A self-tuning two degree of freedom (2-DOF )PID controller based on fuzzy inference is presented. In view of the deficiency of conventional 2-DOF PID controller in the parameter time varying system, integrate the two-degree-of-freedom PID control with fuzzy techniques, a self-tuning PID controller based on fuzzy inference is designed. On-line automatically tuned parameters are realized at different...
In order to apply evaporative cooling technical to a high voltage and large capacity turbo-generator that will be used for a main power generator, the problem of designing reasonable insulation structure is needed to be solved. This paper offers immerging evaporative cooling stator, according to its specialties. This paper calculates and analysis the electric field and the temperature field in immerging...
This paper presents a decoupling method for speed-sensorless vector control of induction motor to track the flux command fast and eliminate torque ripples in flux-varying environment, such as field-weakening operation and efficiency optimization. Rotor flux-oriented control can decouple the speed and flux control. However, the decoupling is on the condition of a constant rotor flux. When motor drives...
A novel V/F induction motor control system based on stator voltage oriented method is presented. This scheme includes dead time compensation, stator voltage compensation and anti-oscillation regulation, which can greatly improve the V/F systempsilas performance especially low frequency load capability and fast response capability. Different from conventional V/F methods, all the compensation and regulation...
This paper presents experimental comparison of the load characteristics of soft magnetic composite (SMC) induction motor and conventional laminated induction motor. SMC is used for the stator core of induction motor. As the result, efficiency difference between SMC motor and conventional laminated motor is only 3.7% in spite of the permeability of SMC is 20% lower than conventional electromagnetic...
This paper presents an improved speed sensorless vector control method for general-purpose induction motors (IMs). The proposed method is based on the d-q axis dynamic model of the induction motor and an improved closed-loop flux observer, which can achieve precise rotor and stator flux estimation over a wide speed range. And then, a rotor-speed-estimation method, based on fuzzy control theory, is...
Direct torque control based on space vector modulation (SVM-DTC) preserve DTC transient merits, furthermore, produce better quality steady-state performance in a wide speed range. In this paper, a torque fuzzy logic controller was designed to substitute the original torque PI controller, and a fuzzy SVM-DTC system based on the torque fuzzy controller was given. A new integration algorithm for estimating...
Induction motor drives without speed sensors have been developed in these years. This paper presents a speed estimation of induction motors by using an observer and PWM carrier frequency components. In this method, three phase triangular carrier waves are used at zero and low frequency and an observer is used at other frequency. The proposed method is not affected from the stator resistance error...
In this paper, a method is presented and achieved to accurately determine Hopf bifurcation point for an induction motor (IM) drive system, and Hopf bifurcation diagram is showed to indicate evolvement of the equilibrium points from steady state to undergoing Hopf bifurcation and then achieving stabilization again. At last, the classical Floquet theory is applied to confirm the limit cyclepsilas stability.
This paper emphasizes to develop a hybrid detection scheme for broken rotor bar fault in induction motors. Since the power spectrum density estimation of classical multiple signal classification (MUSIC) possesses higher resolution with short-time samples compared with FFT, this paper applies MUSIC to detect broken rotor bar fault. And thus, the impacts of the fluctuation of stator current can be decreased...
The broken rotor bar is one of the frequent faults in squirrel cage induction motors. Fault detection based on a common steady-state analysis technique, such as FFT, is significantly dependent on the loading conditions of induction motors. At light load, it is difficult to distinguish between healthy and faulty rotors. This paper provides two detection methods based on digital signal processing system...
To solve the problems with the conventional direct torque control (DTC) of high speed permanent magnet synchronous motors (PMSM), a variable structure sliding mode direct torque control (VSS-DTC) without sensor is proposed in this paper. The control law of high speed PMSM VSS-DTC and the methodology of speed estimation are presented. The simulation model of the sensorless VSS-DTC system is built and...
Direct torque control of brushless DC motor (BLDC) is complex for turn-off phase. And the direct torque control of brushless DC motor based on hyper space vector solved the problem, however, the torque ripple was obvious. A modified method is presented in this paper in order to reduce the torque ripple based on hyper space vector. For the turn-off phase only affects the stator flux linkage but not...
Based on the analysis of the magnetic field, a new simplified radial force analytical model for switched reluctance motors is established in this paper, in which saturation and fringing flux are considered. Moreover, the radial force is predicted by using FEM, and the model is validated by its predictions against those of the finite element method (FEM). Furthermore, the relationships between the...
This paper presents a high performance direct torque control (DTC) theme for the induction motor (IM). To solve those problems associated with conventional DTC, such as high current, flux and torque ripple, variable switching frequency, the space vector modulation (SVM) is implemented in the DTC to guarantee the constant switching frequency of the inverter. Meanwhile, the design of a robust speed...
Due to multivariable, highly nonlinear, strong coupling, time-varying dynamics and unavailability of measurements, induction motor control is still a difficult and complex engineering problem. Vector control has replaced traditional control method using the ratio of voltage and frequency as a constant, which improve greatly dynamic control efficiency of motor. However, under the circumstances of changing...
The eddy loss of stator windings in synchronous generator was calculated using analysis method and finite-element method, the distributed characteristic of stator windings temperature field was studied. In this paper, the distribution characteristic of eddy current of windings in rectangular slot was analyzed first by using analytical method, and the mathematical representations of eddy current were...
This paper investigates the back EMFs of four surface-mounted permanent magnet machines with different winding arrangements for education purpose. They are a): a 4-pole machine with integral-slot distributed winding, b): an 8-pole machine with fractional-slot distributed winding, c): a 12-pole machine with integral-slot concentrated winding and d): a 24-pole machine with fractional-slot concentrated...
This paper presents a new solution, which can completely remove the DC offset and make the dynamic error of flux observation smaller when using the modified voltage model compensated by rotor flux oriented current model. The modified voltage model with error compensation not only completely eliminates the integration drift, but also realizes errorless flux estimation in steady state and dynamic state...
To minimize the ripples of the torque and flux linkage and to fix the variable switching frequency produced in the conventional direct torque control (DTC) system for permanent magnet synchronous motors (PMSM), the fuzzy controller was introduced into the PMSM DTC, and a PMSM Fuzzy DTC system based on DSP TMS320LF2407 was implemented. Experimental results show that the proposed Fuzzy DTC system has...
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