93 research outputs found

    A comprehensive review on brushless doubly-fed reluctance machine

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    © 2021 by the authors. Licensee MDPI, Basel, Switzerland. The Brushless Doubly-Fed Reluctance Machine (BDFRM) has been widely investigated in numerous research studies since it is brushless and cageless and there is no winding on the rotor of this emerging machine. This feature leads to several advantages for this machine in comparison with its induction counterpart, i.e., Brushless Doubly-Fed Induction Machine (BDFIM). Less maintenance, less power losses, and also more reliability are the major advantages of BDFRM compared to BDFIM. The design complexity of its reluctance rotor, as well as flux patterns for indirect connection between the two windings mounted on the stator including power winding and control winding, have restricted the development of this machine technology. In the literature, there is not a comprehensive review of the research studies related to BDFRM. In this paper, the previous research studies are reviewed from different points of view, such as operation, design, control, transient model, dynamic model, power factor, Maximum Power Point Tracking (MPPT), and losses. It is revealed that the BDFRM is still evolving since the theoretical results have shown that this machine operates efficiently if it is well-designed

    A comprehensive review on brushless doubly-fed reluctance machine

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    The Brushless Doubly-Fed Reluctance Machine (BDFRM) has been widely investigated in numerous research studies since it is brushless and cageless and there is no winding on the rotor of this emerging machine. This feature leads to several advantages for this machine in comparison with its induction counterpart, i.e., Brushless Doubly-Fed Induction Machine (BDFIM). Less maintenance, less power losses, and also more reliability are the major advantages of BDFRM compared to BDFIM. The design complexity of its reluctance rotor, as well as flux patterns for indirect connection between the two windings mounted on the stator including power winding and control winding, have restricted the development of this machine technology. In the literature, there is not a comprehensive review of the research studies related to BDFRM. In this paper, the previous research studies are reviewed from different points of view, such as operation, design, control, transient model, dynamic model, power factor, Maximum Power Point Tracking (MPPT), and losses. It is revealed that the BDFRM is still evolving since the theoretical results have shown that this machine operates efficiently if it is well-designed

    Design and Dynamic Control of Heteropolar Inductor Machines

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    Comparison of doubly-fed induction generator and brushless doubly-fed reluctance generator for wind energy applications

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    Phd ThesisThe Doubly-fed Induction Generator (DFIG) is the dominant technology for variable-speed wind power generation due in part to its cost-effective partially-rated power converter. However, the maintenance requirements and potential failure of brushes and slip rings is a significant disadvantage of DFIG. This has led to increased interest in brushless doubly-fed generators. In this thesis a Brushless Doubly-Fed Reluctance Generator (BDFRG) is compared with DFIG from a control performance point of view. To compare the performance of the two generators a flexible 7.5kW test facility has been constructed. Initially, a classical cascade vector controller is applied to both generators. This controller is based on the stator voltage field orientation method with an inner rotor (secondary stator) current control loop and an outer active and reactive power control loop. The dynamic and steady state performance of two generators are examined experimentally. The results confirm that the BDFRG has a slower dynamic response when compared to the DFIG due to the larger and variable inductance. Finally a sensorless Direct Power Control (DPC) scheme is applied to both the DFIG and BDFRG. The performance of this scheme is demonstrated with both simulation and experimental results.Engineering and Physical Sciences Research Council (EPSRC) and Overseas Researcher Scholarship (ORS

    Modelling and practical set-up to investigate the performance of permanent magnet synchronous motor through rotor position estimation at zero and low speeds

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    This thesis provides a study for the rotor position estimation in SM-PMSMs, particularly at zero and low speeds. The method for zero rotor speed is based on injection of three high frequency voltage pulses in the motor stator windings. Then, the voltage responses at the motor terminals are exploited to extract the rotor position. Two approaches, modelling and practical implementations, are presented. The obtained results have showed a verification of a high-resolution position estimation (a position estimation of 1 degree angle), a simplicity and cost effective implementation and a no need for current sensors is required to achieve the estimation process. It should be noticed that the implementation of rotor position estimation at zero speed is only attended when the rotor is at standstill or very low speed. Therefore, the motor driver is not expected to be active at this condition. Thereby, the zero speed estimation does not provide a robust torque control. In future, this should be taking into consideration to overcome this drawback and to make the estimator more reliable. At low speed running, the primary goal is to start spinning the under test motors, and then the rotor position estimation is achieved. The motor spinning is based on adopting a virtual injected signal to generate the voltage components, Vα and Vβ, of the space vector pulse width modulation technique. Then, generating the eight space vectors is conducted through storing the standard patterns of the six space vector sectors in a memory structure together with the timing sequences of each sector. The presented strategy of motor running includes a proposed motor speed control scheme, which is based on controlling the frequency of the power signal, at the inverter output, through controlling the timing period of execution the power delivery program. The thesis presents a proposed method to achieve the estimation goal depends on tracking the magnetic saliency on one motor line voltage. Thereby, the rotor position estimation The introduced proposed method, for rotor position estimation at zero speed, verifies the following contributions: - Presents a simple and cost effective zero speed rotor position estimator for the motor under test. - The aimed resolution in this thesis is an angle 1 degree. IV - Adopting solely the measuring of motor terminal voltages. Eliminating the detection of the rotor magnet polarity as a necessary technique for completing the position estimation. At low speed running, the following contributions are verified: - Rather than a real frequency signal, a virtual injected signal is adopted to generate the voltage components, Vα and Vβ of the space vector pulse width modulation technique. - The proposed method for generating the eight space vectors is based on storing the standard patterns of the six sectors in a memory structure together with the timing sequence. - The strategy of motor speed control is based on controlling the period of execution the power delivery program. - The strategy of low speed rotor position employs one motor line voltage from which the low speed estimation is achieved

    Brushless Doubly-Fed Reluctance Machines for Aerospace Electrical Power Generation Systems

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    This thesis describes a programme of research encompassing the design, optimisation and experimental testing of a brushless doubly fed reluctance machine (BDFRM) for use as an aerospace electrical generator, specifically a direct line connected generator, to widen the input shaft speed beyond the normal constraints imposed by the 360-800Hz specification for a variable-frequency AC aerospace network. BDFRMs offer the functionality of frequency correction, via a control winding, and have the advantage of using a robust reluctance rotor. A partially-rated control winding converter can, in principle, be used to provide the slip power required. A further advantage of the BDFRM is the inherent fail-safe nature of these machines, with the output voltage collapsing as soon as the control winding current has been removed. A synchronous reluctance machine was studied as a means of providing a baseline for the BDFRM performance, including a comparison of the effect of scaling on power density. A large number of time-stepped finite element simulations were undertaken to explore BDFRM performance, in particular, the influence of magnetic saturation in limiting the achievable power density and in compromising power quality. Detailed optimisation of a BDFRM was undertaken, including systematic mechanical design of the rotor for high speed operation. This analysis illustrates the significant compromises in machine electromagnetic performance which result from the need to accommodate mechanical stress. The scope for employing small amounts of permanent magnet material in the rotors of both synchronous reluctance machines and BDFRMs, to improve the machine performance at the lower end of the current density range, was investigated. Following detailed optimisation, a demonstrator machine was manufactured, which includes a skewed rotor. The performance of this machine was measured at a number of test points to verify predictions of output power, voltage and voltage harmonics

    Rotor Position Identification for Brushless DC motor

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    Permanent magnet BLDC motors are characterized by a central magnetic core, called the rotor, and fixed electric coils (usually six) equally spaced in a ring around the core, called the stator. Motor movement is controlled by alternately energizing and de-energizing the stator coils to create a rotating magnetic field that propels the rotor. In order for this process to work correctly, BLDC motors required a technology called electronic commutation, in which the coil currents must be very carefully synchronized to rotor position to ensure that the rotating field is correctly aligned with the permanent magnetic field in the rotor. Usually rotor position is measured by external sensors such as Hall-effect sensors and optical encoders and these external sensors increase the system cost and reduces reliability. In order to control the price and make it more reliable this thesis propose to infer the rotor position from voltage and current measurement of motor. The most common approaches to sensorless control are based on the measurement of the electromotive force (back-EMF), that is induced by the rotor motion. As the back-EMF is nearly zero at very low speed and at stationary position, and can not be measured. Therefore a separate algorithm is required for start-up and control at low speed. The other method of sensorless control involves the inference of rotor position from the variation in inductance caused by rotor position. This thesis presents a prototype system for sensorless control of BLDC motors over the entire speed range of the motor, including stall (zero speed) conditions using the voltage and current signals from the motor
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