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Because of the increasing power density of electric motors, it is anticipated that the oil would not only lubricate the gearbox, but it will also be used as a coolant for the electric motor. TOTAL Quartz EV-Drive MP Technology has been designed as an innovative multi-purpose fluid which meets the new requirements of the combination of electric motor cooling and transmission lubrication. A comprehensive approach which identifies all the new constraints was followed in order to design such a multi-purpose fluid. Oil needs to maximize the heat transfer. Numerical simulations of an electric motor coupled with the data generated on a Stator Cooling Test enable us to identify the electric motor hot spots and to determine the fluid cooling power. As oil will be in direct contact with electrical components, it needs to be electrically insulating to avoid any current leakage. A direct oil cooling system also implies that oil should be inert towards electric motor insulation materials and bare copper. Test rigs were used to assess the oil compatibility with copper and polymer coated wires. Another critical aspect of electric vehicles is the high-speed lubrication properties. Ball bearings could experience lubricant starvation when the electric motor runs at high speed. A High-Speed Ball Bearing Test was designed to assess our fluids in this regard. Transmission components are also running at high speed, which increases oil aeration and churning losses. A specific test rig has also been designed to characterize churning losses at high speed.

Today’s omnipresent environmental problems have led to an increased demand for electrical machines and its subcomponents – i.e. stators, rotors and control units - that show highest quality/price ratios. The flatpack technology is a multiple stage method of bending flat, comb-like stator cores with inserted copper windings into rounded rings. Despite the complexity caused by simultaneously acting bending effects, that stator manufacturing technology provides potentials regarding achievable stator performance due to its relatively high copper fill factor. In previous investigations, numerical models of one single bending operation have been validated. In contrast, this investigation focusses on predicting the stator geometry after multiple bending operations. Therefore, simulation models were extended to calculate such bending processes within one single model. Finally, results gained from experiments and simulation runs with same settings are presented. Discussion of results discloses a conformity between numerical and experimental geometries after multiple bending stages beyond 94%.

This paper presents latest developments and applications of a new electrical motor design which delivers highest power and torque density, while keeping weight and cost at a minimum. This allows for direct drive applications like wheel-hub motors or other mobile drives, where very low weight is mandatory. The motor’s air-gap-winding design reduces the amount of iron and copper and consequently it’s weight and cost significantly. Slotless design completely avoids cogging torque and shows a very smooth operation. The simple geometric design based on two thin-walled hollow cylinders, supports an automated production, which also contributes to very low cost. A flat slotless stator design stands for a homogenous temperature distribution and very efficient cooling, which allows high shortterm overload. In a first application a 40-kW wheel-hub-motor for a 15-inch rim was developed, built and tested. It delivers nominal torque of 300 Nm over the complete range of speed up to 1350 rpm. Total weight of this prototype is only 20 kg. Further applications for an E-Scooter, a Wheel-Hub Generator, an E-Flyboat and an E-Motorbike will be presented. Combining air-gap winding with an additional slot winding boosts torque and power of the motor substantially, without any relevant increase of weight and cost. Both windings share the already existent permanent magnetic field and cooling system, and both contribute to the torque. Converting an existing wheel-hub motor of generation 1 showed a proof of concept by delivering a nominal torque of 450 Nm and nominal power of 60 kW keeping the same size and nearly the same weight. First generation 2 prototypes providing a nominal torque of 600 Nm in a 16-inch wheel rim and a power of 70 kW is designed, built and validated on test stand.

In an effort to meet climate protection targets, countries around the world are promoting electro mobility. As a result of market growth, the worldwide production capacities for electric motors for traction drives is going to expand significantly. Besides, the existing technology must be adapted to automotive- specific life cycle requirements. On the product side, the electric machine has to reach maximum power densities in order to keep the required limitations of space and weight. Furthermore, a fully automated production process is essential to achieve high output rates and required quality standards. The application of new adhesives and bonding processes implements product-relevant properties in the production of components for electric motors. Moreover, the selection of adhesive systems and process parameters is crucial for cost-efficient and high quality manufacturing processes in mass production. In the production of permanent magnet synchronous machines, adhesives are used for joining of lamination stacks, fixation of magnets and the overall assembling of stator housings.

In the study of direct torque control (DTC) of permanent magnet synchronous motor (PMSM), the stator resistance is easily affected by temperature variation and its value varies from time to time. What is more, it will lead to flux ripple. In order to solve the problem of error existing between the set value of the stator flux and the reality, an improved method based on variable parameter PI is proposed to compensate the stator resistance. By constructing the stator flux observer mathematical model of DTC of PMSM and analyzing the stator resistance variation influenced by the stator flux observation, it can be found that the stator resistance is compensated by adjusting PI parameters with time, the flux error will be reduced, and this new method will be testified by MATLAB software. The simulation result shows that the improved stator resistance compensation algorithm has effectively solved the flux ripple problem, decreased the flux error, and achieved the expected control effect.

High-speed train’s traction drive system is a typical electromechanical coupling system, and the motor torque contains ripples of different frequencies and amplitudes. Frequency of motor stator changes with velocity, so the frequency of torque pulsation varies a lot. The driving system has resonance frequency, and the devices would be vibrated when frequency of torque ripple is close to the resonance frequency. First, this paper analyses the torque ripple caused by inverter’s nonlinear factors. Then, the paper establishes the model of shifts to research the vibration frequency. Finally, the author analyses the forced vibration of the mechanical structure excited by torque ripple, and the simulation result shows that the vibration would be aggravated when the frequency of the torque ripple is in accord with the resonance frequency.

In order to study the characteristics of a type of centrifugal compressor with a high pressure ratio and the distribution of the flow field parameters in the design points, CFX software was used to simulate its flow field. According to the results, the pressure ratio and the efficiency of the compressor are high at high RPMS, and the range of mass flow rate is wide at lower RPMS. So the capacity to adapt different working conditions of this compressor is good. At the aspect of the flow field in the design points, the distribution of the overall flow field parameters is homogeneous, but the shock waves exit in the first stator entrance, making the passage narrower and bring much energy loss, which is the one of the reasons to decline the compressor efficiency.

The bearing fault will firstly generate torque fluctuation, then magnetic field in motor is affected, lastly partial bearing fault feature is transferred into stator current. Because of the bearing fault feature is more obvious in magnetic field than those in stator current, the magnetic field frequency feature of the bearing fault is researched. The magnetic field characteristic frequency expression is deduced considering a multiple modulation between torque fluctuation frequency, power supply harmonics, and slot harmonics. The above expression is verified by finite element analysis. Using four search coils which are inserted inside the stator slot to research the magnetic field frequency feature at the actually bearing fault condition, and results verify that the proposed method based on magnetic field frequency feature is feasible and effective.

The power of inverter used for high-speed train traction is very high, so its switching frequency must be reduced to decrease the power loss, but the harmonic of pulse width modulation (PWM) will be large because of the low switching frequency. In order to resolve this problem, a synchronous optimal PWM technology based on flux tracking control is presented in this paper. The switching angles of three phases are got off-line according to the principle that the total current harmonic of motor is minimum. The trajectory of stator flux is regular polygon. As the system is in working state, the flux threshold of special position is calculated in real time, and the output of inverter is got by comparing the stator flux estimated with the flux threshold, so the synchronous optimal modulation based on flux tracking control is realized. The simulation and experiment show that the method presented is feasible and right.

In order to make research on the hoisting mechanism, motor’s energy consumption during the motor’s starting period and smooth running period for the portal crane or overhead crane, the rotational inertia, and load torque of the hoisting mechanism are converted to the rotor side; an equivalent uniaxial motor driving system is derived according to motor driving system of the hoisting mechanism; and the variable frequency control system is designed based on the slip frequency between stator’s synchronous angular speed and rotor’s electric angular speed and it made comparative research about energy consumption with the direct running synchronous motor. The research results showed the following: The variable frequency running motor could vapidly reach the given rotational speed within 0.2 s and could vapidly track the load torque; the frequency and amplitude of the stator’s 3-phase variable frequency modulation voltage would be gradually increasing during the motor’s starting period, and the 3-phase variable frequency modulation voltage would be constant during the motor’s smooth running period; start energy consumption would not exceed 2 × 104 J when variable frequency running motor’s load did not exceed heavy load and the load torque’s effect on the energy consumption wave was small; the motor’s energy saving was obvious during starting period and smooth running period if the variable frequency running motor’s load exceeded medium load.

Induction machines and synchronous machines are rotating field machines. The stator construction of these machine types are principally the same, they differ in the rotor design. The similarity of these machine types are discussed first, later a detailed consideration of induction machine and synchronous machine will follow.

Aiming at the uncertainty of fault diagnosis in turbine generator based on single fault information, a diagnosis system of multi-sensors fusion characteristics based on kernel principle component analysis (KPCA) and mutative scale chaos combined clustering is proposed. Firstly, the vibration features of generator’s stator and rotor and the circulation features of stator winding parallel branch were combined and then with which used KPCA to carry out dimensionality reduction fusion, obtained complementary features and selected nonlinear principal components as fault analysis data, finally used the mutative scale chaos optimization algorithms (MSCOA)-FCM algorithm to realize fault identification. The fault diagnosis example of generator shows the validity and practicability of the algorithm; compared to a single signal source, it has a considerable improvement in the accuracy of fault diagnosis and is more suitable for fault identification.

This paper proposes to recover the concept of spherical induction electrical machines to conceive a shell-like actuator with multi-DOF (Degrees-Of-Freedom). The actuator is formed by a shell stator and a spherical rotor. This work contains the feasibility study of that solution when applied as an active joint actuator in assistive devices. Its electromechanical characteristics are first analyzed using an analytic model that includes: the distribution of the magnetic potential vector and thus the components of the magnetic flux density in the airgap due to a sinusoidal current distribution imposed in the stator; the model also shows the induced electromotive forces and associated current density distribution in the rotor; and at last the radial and tangential components of the force density in the rotor. The shell-like actuator is concretized as an active joint for assisting movement of the lower leg of a typical 70kg person. Based on its requirements, the joint actuator electromechanical characteristics are analyzed according to its sensitivity to a set of electrical and mechanical variables.

A study proposed in this paper is based on EMU traction motor failure. The fault detection method was combination of Hilbert transform and wavelet packet energy analysis. DSP and ARM dual-core CPU and its peripheral devices for the hardware platform. An online monitoring of EMU traction motor fault detection device can be applied to the stator winding fault and broken rotor bars and air gap eccentricity. Fault detection instances in laboratory demonstrate that the approach is valid, effective, and feasible.

Active magnetic bearing (AMB) system supports a rotating shaft, without any physical contact by using electromagnetic forces. This paper proposes an intelligent control method for displacements of the air gap between the stator and the rotor in an Active Magnetic Bearing (AMB) system, using the emerging approaches of the Fuzzy Logic Controller (FLC) and Adaptive Neuro-Fuzzy Inference System (ANFIS). The AMB systems are inherently unstable and the relationship between the current and electromagnetic force is nonlinear. In this paper, the control model uses Takagi-Sugeno fuzzy logic, in which the back-propagation algorithm processes information from neural networks to adjust suitably the parameters of the fuzzy controller. This method can be applied to improve the control performance of nonlinear systems. This controller also satisfies the requirements of real-time response and stability under disturbances of system. The ANFIS controller can be feasibly applied to AMB systems with unbalance mass disturbances.

Permanent magnet (PM) linear motor having magnets and armature windings in the primary mover (the so-called primary-PM machines) have attracted more and more attention due to its definite advantages of robust structure, high power density, high efficiency, and low cost in long stator application. In this paper, the structure, operation principle, characteristics, and electromagnetic performance of two kinds of the primary-PM motors in the application of the rail transit will be presented. Also, some experiment results are given to validate the study.

In this paper, a sensorless vector control method is introduced where rotor speed is estimated based on extended Kalman filter (EKF). The EKF is a recursive optimum stochastic state estimator. The proposed EKF is designed to obtain a small estimation speed error in both transient and steady state over a wide speed range. A major challenge at very low and zero speed is the lost coupling effect from the rotor to the stator, which makes the information on rotor variables unobservable on the stator side. To solve this problem, in the proposed EKF, the load torque and the rotor speed with unmeasurable information are estimated simultaneously. The rotor speed is considered via the equation of motion and the estimation of load torque, on the other hand, is performed as a constant parameter. Hardware and software for experiment of the AC induction motor drive are introduced. The experimental results are presented to show the effectiveness of the proposed system.

When an industrial induction motor is started directly, the stator current is generally 5–7 times greater than the rated one, which makes the voltage sag of the transmission lines increase rapidly, furthermore, affecting the power quality seriously. However, applying variable reactance type motor soft starter to start motors, the starting current of the motor can be reduced effectively. The mathematical model of the soft starter which is based on variable reactance is established, and the relationship between the thyristor conduction angle and the motor current is analyzed. The purpose of the motor and equipment’s protection is achieved by selecting the appropriate conduction angle to control the starting current amplitude.

Active control of rotor–stator interaction noise is studied numerically based on the surface oscillation of stator vanes. The problem is formulated in terms of 3D Euler equations linearized around uniform steady flow. Governing equations are solved with an explicit numerical technique based on a high-order approximation of spacial derivatives. It is found that the acoustic response with actuation on the suction side of the vanes differs considerably from that on the pressure side. The noise radiation also exhibits a strong dependence on the actuation frequency and position on the vane. Noise reduction of up to 80 % can be achieved.

In this paper, we present fault prognosis and diagnosis technique in a three phase asynchronous machine. Based on statistical analysis of scalar indicator resulting from the TSA method (Time Synchronous Averaging), this technique will be dedicated to condition monitoring of machines. In addition, spectral analysis, using the Fast Fourier Transform (FFT) algorithm of the stator- current signature MCSA (Motor Current Signature Analysis), determines their frequency composition, and therefore, allows finding the spectral lines associated to the fault. This work highlights our first results related to the comparison of the spectral representation of the stator current and that of the residual current obtained by the TSA method. We proved the effectiveness of these techniques by simulation and experimental tests made on a wound rotor induction machine. The fault rotor is taken into account by an additional resistance of one of the rotor phases. The results of simulations and experiments underline the practical utility of this method.

The paper reviews the main faults identification of electric machines based on amplitude versus time and amplitude versus frequency vibration analysis. The aim of the paper is to introduce a new method in determining rotor faults based on stator vibration. The analysis method uses a multi-channel vibration analyzer provided with three accelerometers, set in a plane perpendicular to the stator axis. The method is suitable for determining rotor faults generated by the stator vibrations, other than those due to current harmonic components or supply voltage unbalance. The SvanPC software allowed the determination of the characteristics regarding velocity vibration versus time and versus frequency. Their interpretation permitted to determine the fault points on electrical machines in two industrial applications.

The objective of the research work is to propose a Novel Method for Modeling, Simulation and Design analysis of a Self-Excited Induction Machine for Wind Power Generation (SEIMWPG). The earlier models of such generators are facing huge mechanical losses, due to wear and tear in the tightly coupled mechanical gear systems and could not provide maximum efficiency. In this paper, the self-excited induction machine based wind electric generator design has been presented, it is possible to get maximum power with the variation of the mutual inductance of the stator and rotor windings, irrespective of the variation of wind velocities. The complete system is modeled and simulated in the MATLAB / SIMULINK environment.

To control the linear synchronous motorLSM which is used for super speed maglev, the precise position data of high speed running train is needed for generation of synchronized current which is supplied to the stator attached on the guideway. Also to reduce the amount of current input to the stator, the whole guideway is devided into several sections and the power is supplied to the only one section which the train is running on. The poor performance of position detection causes the degradation of LSM propulsion efficiency. Also, the poor section change due to bad LSM control causes the fluctuation of vehicle, which decreases the comfortability. In this study, to evaluate the influence of position detection performance on the LSM and section control, the infinite loop type testbed is developed, and improvement method was investigated.

This paper discusses about simulation of permanent magnet hybrid stepper motor (PMH) magnetic circuit using finite element model using Partial Differential Equation (PDE) toolbox of Matlab. It concludes mmf distribution during excitation due to permanent magnet and excitation coil for eight topologies. Topologies are designed with different airgaps and with different stator teeth.

This paper presents a comparative study of two intelligent techniques to replace conventional comparators and selection table of direct torque control for induction machines, namely fuzzy logic and artificial neural network. The comparison with the conventional direct torque control proves that FL-DTC and NN-DTC reduces the electromagnetic torque ripple, stator flux, and stator current. Simulation results prove the effectiveness and the performances proposed strategies.

An offline two-dimensional SOM neural based algorithm is used in order to supervise a three-phase squirrel-cage induction motor and detect short-circuit incipient fault condition. A sinusoidal PWM inverter is used to feed the motor and some components of the current motor frequency spectrum are used as input variables. A special electrical structure was built to emulate incipient short-circuit at the stator windings of the induction motor. The data were acquired with the motor operating under different frequencies, load level and fault extent. Through the generated data base, the algorithm was tested and a high mean success rate combined with a good visualization of the problem was achieved. In near future, this algorithm can be used as base for an online supervisory system for this kind of motor failure.

This paper proposes a novel control scheme for rotor time constant identification using artificial neural networks. This approach, based on estimation of the rotor time constant from motor terminal variables (stator voltage, stator current and rotor speed), can be applied to indirect field oriented control and used to tune the actual rotor time constant of the induction motor to its set value programmed in the decoupling controller. The neural estimators use the back-propagation learning process to update their weights. The performance of the proposed scheme is carried out by extensive simulations confirming the feasibility of the proposed control strategy.

Some aspects of state variable estimator improvement is proposed in the paper. The estimator approximates stator current components in the rotor flux reference frame with the help of neural networks. Some modification of the training procedure is considered that leads to the estimator accuracy improvement. Provided tests confirmed this feature but further steps are necessary to increase state variables estimation in the low supplying frequency range.

The application of PMSM for electric vehicle driving is more and more widely, but the electromagnetic noise is the main problem which restricts the development of PMSM. The electromagnetic force which acts on motor stator and the structure dynamic characteristics of motor stator are the two key factors which decide the electromagnetic noise of PMSM. In this paper, take PMSM as study object,researches are working hard on the two factors to analyze the electromagnetic noise of PMSM for electric vehicle driving. The author researched generation mechanism of PMSM electromagnetic force, deducted analytical method for electromagnetic force under both no-load and load condition, and then calculated wave orders and frequency of electromagnetic force affecting on stator surface of PMSM. The electromagnetic simulating model of PMSM is built based on electromagnetic simulation software Ansoft, and calculated air-gap flux density using time stepping finite element method under both no-load and load condition, then obtained air-gap flux density spectrum by FFT analysis with simulation results. The author calculated harmonic orders, frequency and amplitude of electromagnetic force by combining calculation results and simulation results. As for structure dynamic characteristics of PMSM, the author built three types of finite element simulation models with stator core, stator core with windings and the whole stator structure. Modal frequency and shape is obtained by finite element modal simulation with three type models. From the results we found that the first six orders modal frequency of the whole stator structure is lower, and the stator structural resonance is easily inspired by the electromagnetic force under both no-load and load condition during speed regulation.

Permanent magnet machines have become prevalent among very high-speed machines and, to the author’s knowledge, no machine other than permanent magnet has been reported to operate beyond the speed of 130.000 rpm. So-called PM synchronous machines (PMSM) with sinusoidal phase currents are generally preferred when low loss and smooth torque are important [1]. On the other hand, using high-frequency sinusoidal currents in the stator makes the design of a power converter more difficult and also complicates the implementation of control algorithm given a short switching period. A control method for PMSM must ensure stable, synchronous operation of the machine at high speeds having, at the same time, computational complexity tolerable by the given microcontroller. Since small high-speed machines, as a rule, lack space for a position/speed sensor, sensorless operation is usually required.

Electrical Power Steering (EPS) is designed to use an electric motor to reduce effort by providing steering assist to the driver. EPS have advantages which are economical and eco-friendly compare with hydraulic power steering, because the power steering oil is not used and efficiency of vehicle increased to 3~5 %. Since EPS is connected to handle of vehicle, acoustic noise and vibration have an effect on the driver directly. So study on the acoustic noise and vibration reduction of EPS is proceeding. In this paper, acoustic noise and vibration reduction of motor are generated by electro-magnetic exciting forces between stator and rotor. The magnetic noise is defined as noise generated from vibrations due to electro-magnetic exciting force. The electro-magnetic exciting force affect on stator yoke, and the acoustic noise and vibration of motor generated by deformation of stator yoke. In order to consider mechanical characteristic, the natural frequency mode of stator is calculated using FEA to avoid resonance. In order to verify proposed method, the proto and improved model are manufactured and experimented.

The complex three-dimensional two-phase flow in a low pressure steam turbine is investigated with comprehensive numerical flow simulations. In addition to the condensation process, which already takes place in the last stages of steam turbines, the numerical flow model is enhanced to consider the drag forces between the droplets and the vapour phase. The present paper shows the differences in the flow path of the phases and investigates the effect of an increasing droplet diameter. For the flow simulations a performance cluster is used because of the high effort for such multi-momentum two-phase flow calculations. In steam turbines the deposition of small water droplets on the stator blades or on parts of the casing is responsible for the formation of large coarse water droplets and these may cause additional dissipation as well as damage due to blade erosion. A method is presented that uses detailed CFD data to predict droplet deposition on turbine stator blades. This simulation method to detect regions of droplet deposition can help to improve the design of water removal devices.

Lean production is an advanced management mode and method, quality management is one of the important management In the enterprise. The paper presents a method of continuous quality improvement with Lean Production and quality management, the mode and method of continuous quality improvement is introduced. the mode and method is implemented in enterprises, focusing the quality problems of the stator manufacture process of permanent magnet motor, production procedure of the products are analyzed, the existing problems are found and improved, the application result is good.

Flow deflection in turbomachines is established by stator and rotor blades with prescribed geometry that includes inlet and exit camber angles, stagger angle, camber line, and thickness distribution. The blade geometry is adjusted to the stage velocity diagram which is designed for specific turbine or compressor flow applications. Simple blade design methods are available in the open literature (see References). More sophisticated and high efficiency blade designs developed by engine manufacturers are generally not available to the public. An earlier theoretical approach by Joukowsky [1] uses the method of conformal transformation to obtain cambered profiles that can generate lift force. The mathematical limitations of the conformal transformation do not allow modifications of a cambered profile to produce the desired pressure distribution required by a turbine or a compressor blade design. In the following, a simple method is presented that is equally applicable for designing compressor and turbine blades. The method is based on (a) constructing the blade camber line and (b) superimposing a predefined base profile on the camber line. With regard to generating a base profile, the conformal transformation can be used to produce useful profiles for superposition purposes. A brief description of the Joukowsky transformation explains the methodology of symmetric and a-symmetric (Cambered) profiles. The transformation uses the complex analysis which is a powerful tool to deal with the potential theory in general and the potential flow in particular. It is found in almost every fluid mechanics textbook that has a chapter dealing with potential flow. While they all share the same underlying mathematics, the style of describing the subject to engineering students differ. A very compact and precise description of this subject matter is found in an excellent textbook by Spurk [2].

In the high-speed traction permanent magnet synchronous motor (PMSM) drive system, control methods without position and speed sensors are adopted because of occupying smaller space, lower cost, higher reliability and less sensitivity to the environment which is more suitable for motors using in traction vehicles. According to the stator voltage and measured current, the stator flux is integrating from the difference value of the voltage, where back-EMF can be calculated and rotor position can be estimated. Based on the estimating method of integrating back-EMF, this paper proposes a modified integrator to solve the problems produced by the pure integrator, which brings up DC offset to estimating motor flux. Simulation and experiment results show that this integrator can accurately estimate both the magnitude and the phase angle of the motor flux, including the speed of PMSM. Besides, the perfomance of the integrator shows that it has good dynamic and steady characteristics.

This paper proposes a sliding-mode observer based rotor flux estimation scheme for induction motors. The sliding-mode observer is designed to track the stator currents and the control signals of the observer are used to estimate the rotor flux. The proposed rotor flux estimation scheme utilizes the stator currents, but does not need the stator voltage. It has significant advantages in practical applications, especially for sensorless Field Oriented Control (FOC) of induction motors. Some simulations are carried out to validate the proposed rotor flux estimation scheme.

The phenomena of stability of laminar flows, transition, and turbulence were systematically studied first by O. Reynolds [1] in the eighties of the eighteenth century. H. Schlichting [2] and [3] and in his classical textbook Boundary Layer Theory [4] gives an excellent treatment of these complex flow phenomena and critically reviews the contributions up to 1979, where the seventh and last edition of his book appeared. In this chapter, we first treat the fundamental issues pertaining to the subject matter followed by original contributions recently made in the area of steady and unsteady boundary layer transition. The flow in a turbine or compressor component is characterized by a threedimensional, highly unsteady motion with random fluctuations due to the existing freestream turbulence and the interactions between the stator and rotor rows.

Determining the number of broken bars due to the failure or the number of ring segments of the rotor cage of the asynchronous motor is the important problem during the operation of such machine. UKF filter, used to achieve this goal, gave exact information: numbers of broken bars and ring segments. For receiving such exact information the filter needed the measurements of the stator currents and currents of the additional one-winding coils placed at stator teeth and loaded by big resistance (~1 kΩ). The measurement of the rotation speed of the rotor and connected with this the angle of the machine shaft rotation was needed also. The method of determining the numbers of broken bars and ring segments of the rotor and the method of detecting only the broken bars of the rotor cage were tested. The presented method can be used for protecting big and expensive asynchronous drives.

The new grid rules require the wind generators should have the ability of the low voltage ride-through, and it’s very important for the safety and stability of power system. In order to restrain the rotor of the doubly fed induction generator appearing over-voltage and over-current shock under the grid faults, the doubly- fed machine system had been established, after considering the electric network fluctuation. The paper presented the improved strategy of the stator flux vector to control the generator speed and stator output reactive power. The numerical simulation in MATLAB shows that the method effectively improved the control for the rotor current under grid faults, enhance the stability of power system and the ability of low voltage ride through.

Due to high operation efficiency and control flexibility, the AC excited double-fed induction generator can not only realize Variable-speed constant-frequency (VSCF), a new typed operational mode for the doubly fed induction generator based wind power generation system is proposed based on the grid-connected power transmission. A control method aimed at increasing efficiency and maximizing energy capture using the stator flux-orientation control technology is introduced. the excitation controller was achieved using fuzzy-PID control. The results of simulation and experimental study testify the feasibility of the proposed strategy, meanwhile validate the optimal power efficiency tracking and optimal wind power capturing can be achieved.

This paper presents a fault identification system for doubly fed induction generator (DFIG). It considers cases of single phase short-circuits and load switching. The system uses the fast fourier transform (FFT) to preprocessor data, which consist by the stator line currents. The principal component analysis (PCA) is employed to reduce the dimensionality of the output data of FFT and the fault identification is made by means of artificial neural network (ANN). Also, a post-processing (PP) is employed in order to increase the network reliability, which reduces the error of ANN. The system is simulated in the MATLAB simulation software using a database with different voltage, speed and load. The results show that the system with PCA, FFT and ANN has a good performance and accuracy with the PP to fault identification in the DFIG.

Permanent magnet synchronous motors (PMSMs) have been more and more interesting for railway vehicle traction system because of their high efficiency and light weight. For the existing of permanent magnet material, the back EMF can be generated during coasting. The inverter components may be destroyed without proper control, when the peak value of back EMF is higher than its withstand voltage. Presently, there are two ways to solve the problem: reducing synthesized air-gap flux linkage by adding negative d-axis current during coasting which can reduce the efficiency, or adding some contactors between inverter and PMSM which is commonly used. But when close the contactors, the phase and frequency of the output voltage of inverter should agree with that of the back EMF to ensure system security. In this paper, an integrated control method of PMSMs during coasting when applied to high speed train is proposed. Based on the mathematical model of PMSM in the synchronous rotating reference frame, the relationship between stator currents, stator voltage and back EMF is analyzed. Then a closed-loop restarting control method after coasting is designed: add an gradual voltage to ensure the smooth switching from coasting to traction or brake. As it has turned out by the simulation results, the method is correct and effective.

In this paper, the nonlinear vibration of the of robotic manipulator with parallelogram hinged mechanism is studied. The relation between the nonlinear vibration of the system and the parameters of the system is obtained. The studies show that the nonlinear resonance of the system are not only related to the structure parameters of the robotic manipulator, but also to the rotational frequency of rotor and the rotating field frequency of stator of the controllable motor, and that under certain conditions, there exist internal resonance, super-harmonic resonance, 1/2-order sub-harmonic resonance, 1/3-order sub-harmonic resonance, combination resonance, and multiple resonance.

The process of electric generator stator bar-ends cure-heating is a key step during the generator production. The paper makes a thermal chemical analysis of the cure-heating system, then builds a thermodynamics model. To control the non-linear and one-step inertial system, it adopts the method of Fuzzy self-tuning PID parameters to adjust the PID parameters including, and the output according to the real-time heating temperature feedback, thus, controlling the heaters action to achieve the objective of heating temperature control and solving the strong-coupling between the multi-loops of heating and improve the automatic control degree of the cure- heating control system. By simulating in MATLAB results show that the fuzzy PID control is better than traditional PID control. As it can not only exploit the advantages of Fuzzy control, but also possesses the high quality dynamic tracking function and better static precision of PID control.

Estimation of rotor resistance rapidly and accurately has received a lot of attention due to its significance in improving the performance of induction motor(IM) vector control system. In this paper, algorithm of estimating rotor resistance of IM based on extended Kalman filter(EKF) is presented. The algorithm can estimate the rotor resistance on line by measuring the voltage, current and speed of stator. Using MATLAB/SIMULINK, a simulation model is built and tested. The simulation results show that the presented algorithm is effective and accurate.

Various simulation models are set up and closed speed loop control strategy of PMSM is proposed based on flux weakening control in this paper. First the model of maximum torque per ampere(MTPA) is modeled based on mathematical models and gave the corresponding simulation tests. Second the formulas are given to calculate the reference of stator current. Third the mathematical model is given to calculate q-axis current component and its detailed analyses. Fourth the modeling of PMSM is given in detail. Finally, simulation experiments are done. All the simulation experiments have verified that the models built in this paper are correct, and the closed speed loop control strategy is feasible and controlled very well. Also electromagnetic torque and three-phase stator currents are controlled well.

This paper presents a synthesis method of magnetic levitation force in spherical permanent magnet (PM) motor, which overcomes the adverse impact of friction torque because there is no direct contact between the stator and rotor. Using the theorem of force translation, Lorentz force of a single coil is equivalent to a force and a moment of couple exerted on the rotor center, so the independent control on levitation force can be achieved. This paper analyzed the position change of stator coils in spherical coordinates when the eccentric rotor moves in three degrees-of-freedom (3-DOF), and then the control equation of levitation force is established. The required magnetic levitation force can be synthesized by controlling the stator currents. Simulation model in MATLAB is created, furthermore the relationships between coil currents and magnetic levitation force, eccentric deviation are studied. The results show that the synthesis method of levitation force is feasible and can provide a basis for control system design.