23,573 research outputs found

    Unified Direct-Flux Vector Control for AC Motor Drives

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    The paper introduces a Unified Direct-Flux Vector Control scheme suitable for sinusoidal AC motor drives. The AC drives considered here are Induction Motor, Synchronous Reluctance and synchronous Permanent Magnet motor drives, including Interior and Surface-mounted Permanent Magnet types. The proposed controller operates in stator flux coordinates: the stator flux amplitude is directly controlled by the direct voltage component, while the torque is controlled by regulating the quadrature current component. The unified direct-flux control is particularly convenient when flux-weakening is required, since it easily guarantees maximum torque production under current and voltage limitations. The hardware for control is standard and the control firmware is the same for all the motors under test with the only exception of the magnetic model used for flux estimation at low speed. Experimental results on four different drives are provided, showing the validity of the proposed unified control approac

    Design and flux-weakening control of an interior permanent magnet synchronous motor for electric vehicles

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    Permanent magnet synchronous motors (PMSMs) provide a competitive technology for EV traction drives owing to their high power density and high efficiency. In this paper, three types of interior PMSMs with different PM arrangements are modeled by the finite element method (FEM). For a given amount of permanent magnet materials, the V shape interior PMSM is found better than the U-shape and the conventional rotor topologies for EV traction drives. Then the V shape interior PMSM is further analyzed with the effects of stator slot opening and the permanent magnet pole chamfering on cogging torque and output torque performance. A vector-controlled flux-weakening method is developed and simulated in matlab to expand the motor speed range for EV drive system. The results show good dynamic and steady-state performance with a capability of expanding speed up to 4 times of the rated. A prototype of the V shape interior PMSM is also manufactured and tested to validate the numerical models built by the finite element method

    Electrification of hydraulic systems using highefficiency permament magnet motors

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    In this paper, electrification of hydraulic systems is proposed using high-efficiency permanent magnet (PM) motors and wide bandgap power electronic drives. Direct driven hydraulics (DDH) is selected because of its higher efficiency compared to other conventional technologies such as valve-controlled systems. The DDH is directly driven by a servomotor. The ratings and design guidelines for a servomotor used in DDH applications are provided in this paper. Specifically, a surface permanent magnet synchronous machine (SPMSM) is designed. Finally, a state-of-the-art inverter using silicon carbide wide bandgap devices are designed for high performance operation

    Robust Online Magnet Demagnetization Diagnosis in Asymmetrical Six-Phase AC Permanent Magnet Motor Drives

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    Rotor magnets are critical components, which in case of fault, directly affect the performance of drives based on permanent magnet synchronous motors. Thus, monitoring the rotor magnets status is essential to ensure both high level of efficiency and service continuity. The present study focuses on the investigation of a new full-time domain-based method for the diagnosis of incipient rotor magnet demagnetization in a vector-controlled asymmetrical six-phase surface-mounted ac permanent magnet synchronous motor. The proposed strategy evaluates the rotor magnet demagnetization using a fault index derived from the control signals synthetized in the 5th subspace, and already available in the control system platform. The main advantages of the proposed new strategy are its simplicity of implementation, and effectiveness even under time-varying operating conditions as the employed control signals in specific subspaces have a dc behavior. Extensive numerical simulations and experimental tests, carried out at different speed and load levels, have shown the validity of the proposed method, leading to an effective diagnostic procedure for a vector-controlled asymmetrical six-phase surface-mounted ac PMSM

    Electric elevator drive with position control

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    This thesis is a study on the implementation of an elevator’s position-controlled electric drive. The information contained within this paper serves as a framework to expand the usefulness of electric drives through the addition of digital control systems and switching power supplies. The tangible example of an elevator driven by a permanent-magnet DC motor is used for this paper so that students may relate to the work and apply it to their future projects. The tasks to be accomplished in order to achieve an electric elevator drive with position control are: determining the parameters of the permanent-magnet DC motor, designing a control system to direct the motor as desired, and verifying the performance of the system through use of computer simulations and experimental testing. The tests to derive the motor parameters as well as the theory behind the test are covered in depth before the design procedures for creating a cascaded control system are started. Computer simulations are conducted using the parameters and controllers which will be implemented in real-time before experimental testing in the lab begins. Conclusions are drawn about the performance of the position-controlled electric elevator drive based upon the simulation and experimental results. The implementation of an elevator driven by a permanent-magnet DC motor with position control is successful and provides an illustrative example to those who wish to apply electric drives to various mechanical system

    On the stator flux linkage estimation of an PMSM with extended Kalman filters

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    The demand for drives with high quality torque control has grown tremendously in a wide variety of applications. Direct torque control (DTC) for permanent magnet synchronous motors can provide this accurate and fast torque control. When applying DTC the change of the stator flux linkage vector is controlled. As such the estimation of the stator flux linkage is essential. In this paper the performance of the Extended Kalman Filter (EKF) for stator flux linkage estimation is studied. Starting from a formulation of the EKF for isotropic motors, the influence of rotor anisotropy and saturation is evaluated. Subsequently it is expanded to highly isotropic motors as well. In both cases the possibilities to add parameter estimations are evaluated

    Design and Modelling of Axially-Laminated Interior Permanent Magnet Motor Drives for Field-Weakening Applications

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    This thesis is concerned with the design of AC motors to operate at constant shaft power over the widest possible speed range from an inverter of fixed volt-ampere rating. In particular, it examines and validates the reputation of the interior permanent magnet motor drive of having a wide speed range at constant power (field-weakening range). The design and construction of a 7.5kW axially-laminated interior permanent magnet motor showing a constant-power speed range exceeding 7.5:1 is described. This result cannot be matched by any other motor type. Vector-controlled induction motor drives are widely used for field-weakening applications. They offer a constant-power speed range of up to about 4:1. Higher values can be obtained only by oversizing the drive or by using a winding changeover technique. Combined with improvements in low-speed dynamic performance, the inherently wider constant-power speed range makes the interior permanent magnet motor drive a serious contender for applications such as machine tool main spindle drives and traction. The thesis consists of two parts. The first part examines the theoretical and practical limitations to the field-weakening performance of the three types of brushless synchronous AC motor : the surface permanent magnet, the synchronous reluctance and the interior permanent magnet motor. It is shown that high-saliency interior permanent magnet motor drives should offer the best practical field-weakening performance. The axially-laminated (as opposed to the conventional radially-laminated) construction offer the highest saliency ratios. The second part describes the modelling and design of an axially-laminated interior permanent magnet motor drive for optimal field-weakening performance. The effect of varying the design parameters on the drive's field-weakening performance is analysed. A 7.5kW axially-laminated synchronous reluctance and a 7.5kW axially-laminated interior permanent magnet motor were built. The interior permanent magnet motor drive shows an extremely wide constant-power speed range which exceeds 7.5:1

    Neural network contour error prediction of a bi-axial linear motor positioning system

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    In the article a method of predicting contour error using artificial neural network for a bi-axial positioning system is presented. The machine consists of two linear stages with permanent magnet linear motors controlled by servo drives. The drives are controlled from a PC with real-time operating system via EtherCAT fieldbus. A randomly generated Non-Uniform Rational B-Spline (NURBS) trajectory is used to train offline a NARX-type artificial neural network for each axis. These networks allow prediction of following errors and contour errors of the motion trajectory. Experimental results are presented that validate the viability of the neural network based contour error prediction. The presented contour error predictor will be used in predictive control and velocity optimization algorithms of linear motor based CNC machines
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