1,721,013 research outputs found
Hybrid Excitation PM Synchronous Motors: Part I Per Unit Analysis
No full textA synchronous machine is analysed, characterised by a rotor including both Permanent Magnets (PMs) and excitation winding. The PMs produce a fixed flux while the excitation winding is adopted to modulate the rotor flux. The nominal point and flux-weakening performance of such a synchronous machine is compared to that of a more commonly used PM machine, to the aim of highlighting advantages and drawbacks. For the sake of achieving a more general comparison, a per unit system is introduced. Thanks to this normalization all the combinations of the machine parameters are taken into account, for both standard PM and HEPM machine. Fixing the same performance at nominal speed, it is shown that the HEPM machine exhibits a higher capability and power factor equal to one during flux-weakening operations. The possibility to modulate the rotor flux allows to overcome the speed limit of the standard PM machines and to keep a high torque and power in a wide range of speeds
Hybrid Excitation PM Synchronous Motors: Part II - Finite Element Analysis
No full textThis paper deals with the finite element analysis of Hybrid Excitation Permanent Magnet Synchronous Motors, that is, synchronous motors characterised by a rotor including both permanent magnets and an excitation winding. Such a winding is adopted to modulate the rotor flux so that the motor exploits the maximum torque for any operating speed. The higher benefit is obtained at speeds higher than the nominal speed, i.e. during the flux weakening operations. Thus the focus is to determine the flux weakening performance of different topologies of hybrid excitation PM synchronous motors, considering different topologies. In addition, the performance parameters are compared to those achieved with a standard interior PM synchronous motors. The possibility to vary the rotor flux in the hybrid excitation PM motors allows to design the motor with a high no-load flux linkage, necessary to get high torque at low speeds, and to get high torque in a wide speed range
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Flux-Weakening Control of Hybrid-Excited Permanent Magnet Synchronous Motors
No full textThis paper deals with the flux-weakening control of hybrid-excited permanent magnet synchronous motors. The flux-weakening operation is achieved by acting both on the stator winding currents and on the rotor excitation winding current. On one hand, a voltage loop is designed for the stator current control, including a proper linearization of the loop. On the other hand, the excitation current reference is generated in a feed-forward manner by reducing the rotor flux linkage for increasing working speeds. The proposed control strategy was validated by means of simulations, comparing the behavior of hybrid-excited permanent magnet motors at high speed with the one of an interior permanent magnet having equal rated parameters
Maximization of Sensorless Capabilities of Hybrid Excited Permanent Magnet Motors
No full textThis paper proposes an improved control strategy for hybrid excited permanent magnet (HEPM) motors in low-speed sensorless operating condition. In low speed region, the rotor position is retrieved by exploiting the rotor anisotropy via high frequency (HF) voltage signals. Non-zero cross-differential inductances induce an estimation error which could lead lower performance and instability issues. The proposed method exploits the excitation current of HEPM motor to reduce or even nullify the estimation error. The operating trajectory for stator and excitation currents is obtained via a two-step optimization procedure. The algorithm aim is the minimization of the position estimation error and the maximization of motor efficiency, by respecting the motor constraints. Simulation results validate the effectiveness in the position error reduction. Moreover, the efficiency of the drive under the proposed control strategy is compared to the benchmark maximum-torque-per-ampere policy
Design of High Power Density IPM Machines with Fractional or Integral Slot for Off-Highway Vehicles
No full textDynamic model for HEPM motors including the nonlinear magnetic characteristics
No full textHybrid excited permanent magnet synchronous motors represent a cutting-edge technology that combines the strengths of permanent magnets with the controllability of an wounded rotor motor. While this presents a unique opportunity for high-performance machines, it also presents a challenge in terms of modeling the current-to-flux-linkage characteristics due to the additional degree of freedom and nonlinearities arising from iron saturation and magnetic cross-couplings. Accurate dynamic models for hybrid excited machines require the inversion of the characteristics. A comprehensive review of state-of-the-art models is presented, and a novel current-based dynamic model that accounts for all magnetic cross-couplings is proposed. The proposed model not only surpasses existing models in terms of accuracy but also enables simulation of phenomena crucial for sensorless applications. The validity of the proposed model is rigorously established through experimental measurements on a prototype machine
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