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A black-box behavioural model for a permanent magnet generator (PMG) for aerospace applications is developed. The model is well-suited to system-level simulation and stability analysis as it is simple and requires no prior knowledge of the internal structure of the system. It is also able to accommodate the non-linear behaviour of the PMG system over the full speed and load range. A polytopic approach...
An alternative approach to DC link capacitance reduction and ripple suppression of single phase power factor correction circuits is presented. While the hardware part of the solution, consisting of a DC-DC converter transferring the oscillating power component to a reduced auxiliary capacitance is similar to other active solutions proposed in the literature by far, the operation principle is entirely...
This paper presents an initial investigation into the application of magnetically geared Pseudo Direct Drive (PDD®) electrical machines to the electromechanical actuation of an aircraft primary flight control surface. Different PDD winding topologies, normally adopted to achieve fault tolerance in conventional permanent magnet machines, are compared, in terms of reliability. Furthermore, the dynamic...
This paper addresses the technical issues in the energy efficiency assessment for inverter-fed motor drives according to the international technical standard (TS) IEC 60034-2-3:2013. The critical points on the TS procedure are investigated by means of experimental results, with special emphasis on the influence of the DC bus voltage, the thermal aspects, the dead-times influence and compensation on...
Full speed range sensorless control is usually faced with two different approaches: bemf- or flux-based reverse model for medium/high speed operation and high frequency (hf) voltage injection for zero/low speed operation. Both approaches require the knowledge of the current-to-flux behavior for gain tuning, error prediction/compensation, applicability evaluation of one or the other of the approaches...
The objective of this paper is to design and implement an economical and efficient single phase dynamic voltage restorer (DVR) that compensates for voltage sag conditions. In this paper, different techniques of voltage sag detection are compared according to their advantages and disadvantages. Root-Mean-Square (RMS) technique is employed to detect the voltage sag event, due to its simplicity and fast...
Many types of models have been developed for the voltage source inverter taking into account non-ideal effects, such as voltage drops over the semiconductors, non-ideal switching characteristics and turn-on delay times. However, uncertainties caused by measurement errors during the identification and during the operation of the model have been neglected so far. Nevertheless, the consideration of these...
Unbalanced Magnetic Pull (UMP) occurs when there is rotor eccentricity in an electrical machine which accelerates bearing wear caused by the unbalanced force. An analytical model is developed by using the flux distribution ratio in the airgap, verified using a finite element model. The paper uses the model to investigate UMP in an induction machine at different slip. It uses a UMP/Torque ratio to...
Flux observers in direct torque controlled (DTC) interior mounted permanent magnet (IPM) machine drives are of paramount importance as the drives rely on observed flux for control of the machine flux and torque. It is well known that a current based (CB) observer performs better at low speeds, whereas a voltage based (VB) observer is more accurate at high speeds. Hence, a large number of state-of-the-art...
An induction generator has been designed for use in an open centred tidal turbine. Mechanical constraints in the turbine design enforces a large magnetic gap in the generator, which inherently limits the power factor. The large diameter of the machine means it is likely to be constructed out of a number of segments, which can each be modelled independently and approximated to either linear segments...
In order to improve accuracy and reduce model setting-up and solving time in thermal analysis of electrical machines, transformers and wound passive components, the multi-material winding region is frequently homogenised. The existing winding homogenization techniques are predominantly focused on winding constructions with round conductors, where thermal conductivity across conductors is usually assumed...
Grain boundary diffusion processed magnets provide advantages when applied in permanent magnet machines subject to high load and high temperature operating scenarios by preventing or reducing the onset of demagnetization. To investigate how grain boundary magnets affect the performance of interior permanent magnet (IPM) machines, one of the challenges is to model the magnet with grain boundary characteristics,...
Adjustable Speed Drives (ASDs) are widely used in three-phase multi-drive applications in industry, where low-cost Diode Rectifiers (DRs) or Silicon-Controlled Rectifiers (SCRs) are still employed as the front-ends in practice, also for simplicity. However, the associated harmonics are produced at the grid, which has to be addressed properly according to increasingly stringent standards and/or grid-connection...
Axial Flux Permanent Magnet (AFPM) machines present a lot of advantages over their conventional counterparts. They are being developed for various applications ranging from consumer electronics to more electric aircrafts [1]. An AFPM machine employing Halbach array offers a number of attractive features over a standard AFPM machine. In this paper both machine topologies are studied comparatively and...
A proportional base driver circuit for SiC bipolar junction transistors is presented. A current transformer feeds a proportion of the transistor's collector current into its base. The influence of the current transformer's magnetising current on its output current is addressed, as are minimum reset time restrictions. The circuit applies a negative off-state base-emitter voltage. Combining this and...
Virtual prototyping of power electronics systems can enable rapid and iterative design process, and can satisfy the need for higher power density. Thermal modelling is a key part in the multi-physics virtual prototyping. In this paper, the T-type steady-state lumped-parameter model (LPM) for a naturally cooled heat sink with a power device on top is established. Empirical equations for the convection...
The grid impedance is time varying due to the changing structure of the power system configuration and it can have a considerable influence on the control and stability of grid connected converters. This paper presents an online grid impedance estimation method using the output switching current ripple of a SVPWM based grid connected converter. The proposed impedance estimation method is derived from...
Transformer-less, grid connected, photovoltaic inverter systems are becoming increasingly popular due to their reduced volume and high efficiency performance. However, the potential risk of dc current injection into the grid is of significant concern in such systems, and strict guidelines and standards are normally in place to protect the integrity of the distribution network. Nevertheless, accurate...
The size of the LCL filter can be decreased significantly using higher switching frequencies enabled by next generation semiconductors. This paper studies the effects of the switching frequency of a grid converter on the LCL filter design. The goal in the design is to minimize the stored energy of the magnetic components. The core material of the converter-side inductor is selected based on the highest...
Electrical vehicles (EVs) have attracted the attention from the entire world for their potential use in future transportation system. As the crucial drive component for EVs, various types of electrical machines have been evaluated in terms of efficiency, power/torque density, speed range, fault tolerance, etc. This paper investigates the optimization method of the electrically excited synchronous...
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