Slip Frequency Research Articles

Modeling and Simulation of Vector Slip Frequency Control System of Induction Motor

This paper is based on MATLAB / SIMULINK software for induction motor slip frequency vector control system. Modeling and simulation results show that to get the motor torque ripple is small with this method, and the system meets the general electrical apparatus speed performance required by smooth speed. Effective control of induction motors can be achieved. With the simulation results, it can guide system debugging and installation and having a good application value.

Control Strategy and Dynamic Performance of Dual Stator-Winding Induction Generator Variable Frequency AC Generating System With Inductive and Capacitive Loads

This paper presents the control strategy and dynamic performance of the dual stator-winding induction generator variable frequency ac (VFAC) generating system with inductive and capacitive loads. In this generating system, the power winding produces the VFAC electricity to feed loads, and the control winding is connected to a static excitation converter to keep the output voltage stable. Based on the change law of the reactive power provided by the control winding, an improved instantaneous slip frequency control (IISFC) strategy both with the load active and reactive power feedforward is proposed to improve the system dynamic performance. The information of the load active and reactive power is employed through two feedforward loops to rapidly change the reactive power provided by the control winding, so as to quicken the regulation of the slip frequency and excitation reactive power. The simulations and experimental results show that the system using the IISFC strategy has a good dynamic performance with inductive and capacitive loads, and demonstrate the correctness and validity of the proposed control strategy.

Hering‐Breuer evoked regulation of respiratory rhythm variability in rats (686.25)

Hering‐Breuer‐related afferent activity affects respiratory patterning in disparate ways: constant mechanical ventilation entrains the respiratory rhythm; yet removal of vagal feedback reduces respiratory rhythm variability. We hypothesize that these effects are mechanistically linked and test this hypothesis by closing the Hering Breuer Reflex feedback loop via rhythmic vagal nerve stimulation in situ before and after suppressing activity in the nucleus tractus solitarii (nTS) or Kölliker‐Fuse nuclei (KFn) by microinjection of muscimol, a GABAAR agonist. We measured feedback‐evoked entrainment of respiration and the variability of the rhythm in the presence or absence of periodic vagal feedback. Rhythmic vagal feedback evoked periods of entrainment interposed by phase slips. Analysis of respiratory rhythm variability revealed that vagal feedback amplified intrinsic respiratory rhythm variability via the transitions from a phase slip to stable entrainment. Suppressing nTS activity eliminated both entrainment and variability amplification. Suppressing KFn activity increased entrainment strength, reduced phase slip frequency and blunted variability amplification. We conclude that 1) Hering‐Breuer feedback inputs are sufficient to amplify respiratory variability via a noisy synchronization mechanism and 2) both entrainment and variability depend on KFn and nTS activity.Grant Funding Source: Supported by NS069220 and T32 HL007913

Analysis and Compensation of Current Measurement Errors in a Doubly Fed Induction Generator

It is necessary to measure the current of rotor for controlling the active and reactive power generated by the stator side of the doubly fed induction generator (DFIG) system. There are offset and scaling errors in the current measurement. The offset and scaling errors cause one and two times current ripples of slip frequency in the synchronous reference frame of vector control, respectively. This paper proposes a compensation method to reduce their ripples. The stator current is variable according to the wind force but the rotor current is almost constant. Therefore input of the rotor current is more useful for a compensation method. The proposed method adopts the synchronous d-axis current of the rotor as the input signal for compensation. The ripples of the measurement errors can be calculated by integrating the synchronous d-axis stator current. The calculated errors are added to the reference current of rotor as input of the current regulator, then the ripples are reduced. Experimental results show the effectiveness of the proposed method.

Development of a high slip-resistant footwear outsole using a hybrid rubber surface pattern.

: The present study examined whether a new footwear outsole with tread blocks and a hybrid rubber surface pattern, composed of rough and smooth surfaces, could increase slip resistance and reduce the risk of fall while walking on a wet floor surface. A drag test was performed to measure static and dynamic coefficient of friction (SCOF and DCOF, respectively) values for the footwear with the hybrid rubber surface pattern outsole and two types of commercially available boots that are conventionally used in food factories and restaurant kitchens with respect to a stainless steel floor covered with glycerol solution. Gait trials were conducted with 14 participants who wore the footwear on the wet stainless steel floor. The drag test results indicated that the hybrid rubber surface pattern sole exhibited higher SCOF (≥0.44) and DCOF (≥0.39) values than the soles of the comparative footwear (p<0.001). Because of such high SCOF and DCOF values, the slip frequency (p<0.01), slip distance (p<0.001), and slip velocity (p<0.001) for the footwear with the hybrid rubber surface pattern outsole were significantly lower than those for the comparative footwear, which resulted in no falls during trials.

Control and Implementation of Dual-Stator-Winding Induction Generator for Variable Frequency AC-Generating System

This paper presents the control and implementation of the dual-stator-winding induction generator for variable frequency AC (VFAC) generating system. This generator has two sets of stator windings embedded into the stator slots. The power winding produces the VFAC power to feed the loads, and the control winding is connected to the static excitation controller to control the generator for output voltage regulation with speed and load variations. On the basis of the idea of power balance, an instantaneous slip frequency control (ISFC) strategy using the information of both the output voltage and the output power is used in this system. A series of experiments is carried out on a 15 kW prototype for verification. Results show that the system has good static and dynamic performance in a wide speed range, which demonstrates that the ISFC strategy is suitable for this system.

Control System Design of Improved Vertical Lifting Stereo Garage with Linear Motor as Transverse Device

Rotating induction motor serving as transverse device in traditional stereo garage makes system complex and inefficient. Installing linear motor in lifting platform as direct drive unit can remove intermediate links and drag vehicle loading board of parking slot directly. In this paper, control system of vertical lifting stereo garage with linear induction motor is put forward, including overall organization, operating principle and software program.Linear motor is controlled by Programmable Logic Controller (PLC) in slip frequency control method and PI algorithm. Experiment results indicate that linear motor can track reference velocitycurveand the whole stereo garage can store and take out vehicles automatically and efficiently.

Simulation Research on Asynchronous Motor Vector Control System

Abstract: the vector control of asynchronous motor variable frequency speed regulating system is a high performance control system, has been used in many high precision, high performance applications applications. In vector transform based many control methods, such as the speed sensorless control and adaptive control, is the development of. In the MATLAB environment, the control of slip frequency vector control system simulation, the simulation experiment shows the fuzzy control simulation results superior to the traditional PI control.

Investigation of Forces in Linear Induction Motor Under Different Slip Frequency for Low-Speed Maglev Application

The linear induction motor (LIM) applied in low-speed Maglev train produces not only the thrust force to drive the train, but also the normal force that affects the levitation system. Three finite element models are employed to investigate the influence of transverse edge effect, longitudinal end effect, transverse edge shape of secondary aluminum plate and its temperature, etc., on the force performance under different slip frequency. For the transverse edge effect, a precise correction factor is proved to be more suitable than the common Russell and Norsworthy's factor. An analytical method using an equivalent circuit model is improved based on an existing model for nonferromagnetic secondary LIM. The amendments account for the primary iron loss, the eddy current of secondary back iron, and the calculation of normal force. Based on this equivalent circuit model, the performance curves of thrust force, normal force, efficiency, and power factor against the train velocity are obtained for given slip frequency and thrust force. The influences of transverse edge, longitudinal end, and air gap length are also investigated. Analytically predicted results are validated by finite element models and measurements.

Control Method of the DFIG Connected to a DC Link through a Diode Bridge

This paper presents a control method for the Doubly-fed Induction Generator connected to a dc link through a diode bridge on the stator. In this system, the rotor is fed, at the slip frequency, by a PWM electronic converter and the stator is directly connected to the dc link using a simple diode bridge. The cost of power electronics is reduced in this system when compared with the classic DFIG machine because the system uses less one PWM inverter and additionally it uses a diode bridge. The application in mind is for microgrids. Microgrids need several elements that should work together. The usual way to connect these elements is to use power electronic devices in a common dc link. This paper presents a new form for the DFIG for this application and presents a control system for the inner control loop. Simulation and experimental results show that the system can work acceptably using a stator frequency near the rated frequency of the machine.

Adaptive AI-based two-stage control for an induction machine drive

In this paper, a two-stage control strategy for speed control of an induction machine drive is investigated by establishing the current input model of an induction motor drive. In order to reduce the effect of machine parameter variations on the performance of the drive, AI-based adaptive neuro-fuzzy controller is implemented to act on both slip frequency and current magnitude. The effect of the load torque variations and rotor resistance variations is observed for the controller.

Rotor Resistance Adaptation Scheme Using Neural Learning Algorithm for a Fuzzy Logic Based Sensorless Vector Control of Induction Motor

This paper presents the Matlab Simulation of fuzzy logic based Sensorless indirect vector control of induction motor with a rotor resistance adaptation. Here the fuzzy controller used for speed controller offers superior transient performance when compared with the conventional control algorithms using PI controller. Rotor resistance of the motor will change significantly with temperature and frequency. This variation has a major influence on the field oriented control performance of an induction motor due to the deviation of slip frequency from the set value. This paper uses neural learning algorithm based rotor resistance adaptation scheme for making the system robust against rotor resistance variation.

The Slip Frequency Control Based on Fuzzy Adaptive PID Algorithm

As three-phase asynchronous motor is a complex system with time-varying multiple-input multiple-output, strong coupling, nonlinear and at least seven order differential equations. So the use of linear and fixed PID parameters to control slip frequency system cannot give well consideration to dynamic and static performance. In order to improve the control effect and enhance the robustness, this paper put forward a slip frequency control scheme of fuzzy self-adaptive PID algorithm, which is based on the complementary combination of advantages between PID control and fuzzy control. The control structure and design method of implementation scheme are given, and the simulation was conducted by MATLAB. The simulation results show that the scheme is feasible as it has better dynamic and static performance than conventional PID control.

Adaptive Speed Observer for a Stand-Alone Doubly Fed Induction Generator Feeding Nonlinear and Unbalanced Loads

In this paper, an improved sensorless control algorithm for a variable speed constant frequency doubly fed induction generator is presented. Unlike previously reported methods the proposed algorithm does not require the rotor position or speed information for the stator field orientation of the rotor variables. The slip frequency is estimated by a reactive power-based model reference adaptive observer and is used in the rotor current controllers for back emf compensation. A new on-line estimation method for the magnetizing inductance of the machine is also proposed to enhance the performance of the controller. Small-signal models of the slip frequency and the magnetizing inductance estimators are developed to aid their design. The proposed algorithm is capable of “speed catching on the fly” and performs satisfactorily with balanced, unbalanced, linear, and nonlinear loads (in any combination) particularly, nonlinear unbalanced loads, which has not been reported in the literature so far. Experimental and simulation results are presented to demonstrate an excellent load voltage regulation property of the control algorithm during severe transient operating conditions. Total harmonic distortion and unbalance of the load voltage and stator current even with large nonlinear/unbalanced loads are also found to be much smaller compared to systems reported earlier.

An Integrated AC and DC Hybrid Generation System Using Dual-Stator-Winding Induction Generator With Static Excitation Controller

This letter proposes an integrated ac and dc hybrid generation system based on the dual-stator-winding induction generator with the static excitation controller (SEC). In this generator, not only the power winding can output the variable-frequency ac power, but also the control winding can provide the high-voltage dc power through the dc bus of the SEC, which implements the electric integration by only one generator. An instantaneous slip frequency control strategy is employed to guarantee the system a good performance. The experimental results verify the correctness and effectiveness of the proposed scheme.

Decoupled control of thrust and normal force in a double-layer single-sided linear induction motor

In this paper, a modified force decoupling method for improved servo control of a magnetically suspended double-layer single-sided linear induction motor (LIM) is presented. In this study, the primary is magnetically suspended under and moved along the double-layer secondary which consists of an aluminum plate with a back-iron. In order to decoupled the normal and thrust force, analytical expressions for the forces as function of the slip frequency and the primary current are obtained by curve fitting on steady-state FEM results. From these steady-state force models, the required current amplitude and slip frequency are solved for given force setpoints. The setpoints are generated by a position controller which is designed based on a dynamical model of the LIM. The dynamical model is estimated by injecting noise into a transient FE-model and measurements. Transient FEM simulations and measurements show the effectiveness of the proposed controller and decoupling method when they are used to magnetically suspend and position the LIM.

Controlling Rotor Vibrations of a Two-Pole Induction Machine With Unipolar Actuator

A three-phase two-pole induction machine has been fitted with coils wound around the machine shaft inside the end shields of the machine. The coils induce unipolar flux in to the machine when supplied with a controllable voltage supply. These windings act as a unipolar actuator that can be used to produce radial force on the rotor. The machine does have a short-circuited extra four-pole stator-winding to reduce unbalanced magnetic pull (UMP) due to the interaction of the two- and four-pole flux components. In two-pole machines, unipolar flux and slot harmonics cause the whirling orbit of an eccentric rotor to pulsate with double slip frequency. The unipolar actuator will mitigate this pulsation when voltage is supplied to the unipolar coils at slip frequency and at correct phase. Current needed to remove pulsation is higher than what is needed to counter the measured unipolar flux. Effects of zero frequency unipolar flux are studied. Theory and measurements are presented.

A Novel Approach to Detect Symmetrical Faults Occurring During Power Swings by Using Frequency Components of Instantaneous Three-Phase Active Power

Since distance relays are prone to interpret a power swing as a three-phase fault, they should be blocked during the power swing to prevent undesired trips. On the other hand, if any fault occurs during a power swing, they should be fast and reliably unblocked. Although unblocking the relay is straightforward in the case of asymmetrical faults by using the zero-sequence and/or negative-sequence component of current, detecting symmetrical faults during a power swing is still a challenge. This paper presents a novel method for detecting symmetrical faults occurring during a power swing. Based on the damping frequency component of 50 (or 60) Hz created on instantaneous three-phase active power profile after inception of a symmetrical fault, the proposed method will be able to detect the fault in less than one power cycle. This detection method can be readily implemented, and is immune to the power swing slip frequency, fault inception time, and fault location. To test the proposed method, several power swings and faults are numerically simulated in MATLAB/SIMULNK, and the simulation results show that the proposed method is sensitive as well as reliable.

Online Tracking of Thévenin Equivalent Parameters Using PMU Measurements

This paper presents a new method for tracking Thévenin equivalent parameters for a power system at a node using local phasor measurement unit (PMU) measurements. Three consecutive phasor measurements for voltage and current, recorded at one location, are used. The phase drifts caused by the measurement slip frequency are first determined and phase angles of the measured phasors are corrected so that the corrected phasors are synchronized to the same reference. The synchronized phasors are then used to determine the equivalent Thévenin parameters of the system.

Research on Squirrel-Cage Induction Generator Full Power Converter Control Strategies of Wind Power Generation System with Dynamic Systems

In this paper, a new control scheme of a variable speed grid connected wind energy generation system was presented. The scheme used a squirrel-cage induction generator (SCIG) as generator and it connected to the grid through a back-to-back double PWM converter. According to the characteristics of induction motor, the generator side adopted rotor flux linkage oriented slip frequency vector control technology, and the grid side used the network voltage oriented control and voltage and current dual close-loop control strategy. The simulation results show that the system can work in the state of variable speed constant frequency (VSCF)power generation and the active and reactive power can be controlled with no mutual interference and with good static-dynamic performance.