Iet Electric Power Applications最新文献

This paper investigates the benefits and challenges of the multi-MW direct-drive offshore wind Vernier generators. It is worth noting that the comparison of generator topologies presented in ref. [1] was for the same power level and therefore a reduced machine volume for the surface-mounted permanent magnet Vernier (SPM-V) generators. This would mainly impact the capital expenditure (CAPEX) cost between the different investigated machines. Whereas in this paper, the performance is compared for the same machine volume that allows the Vernier generators to produce a much higher energy yield than a conventional SPM generator. As the extra energy yield would be beneficial over the lifetime of the turbine, this will have a bigger impact than the CAPEX cost savings with a reduced machine volume. In addition, a novel Vernier machine with magnets on both the stator and rotor has been proposed to further improve the energy yield. In addition to the basic electromagnetic performance, the levelised cost of energy (LCOE) of the three generator topologies, that is, the conventional SPM, SPM-V and the proposed Vernier machines, has been compared. The direct-drive powertrain systems with SPM-V and the proposed Vernier generators can achieve LCOE of 12.3% and 24% lower than that of the conventional SPM generators, indicating their huge potential as an alternative to reduce the overall cost of energy.

Sensorless control of permanent magnet synchronous motor (PMSM) can increase the reliability of electric actuators of more electrical aircraft. Numerical online parameter estimation method will enhance the performance for sensorless control methods based on sliding mode observer (SMO). However, numerical online parameter identification methods typically assume zero rotor position estimation error to ensure full rank of the identification equation set. This assumption actually leads to errors in parameter identification, resulting in steady-state errors in rotor position estimation. This paper focuses on a compensation method for PMSM online parameter identification that takes into account rotor position estimation error. This method is used for sensorless control based on SMO, using model reference adaptive systems for online parameter identification, and no additional parameter adjustment required. Validation is conducted on a PMSM experimental platform with maximum load of 15kW. The experimental results of 1000 r/min steady state operation proved the effectiveness of the method, and the dynamic experiments with 5 and 15kW loads proved that the method has no significant adverse effect on the system dynamics.

The vibration and acoustic noise of a permanent-magnet synchronous motor are analysed and evaluated. Acoustic noise sound levels, their prominent frequencies, and the noisiest motor speed range are predicted. According to many resources, the radial vibration of the stator system due to the magnetic attraction between rotor permanent magnets and stator iron teeth is the main reason for the acoustic noise propagation of the PMSMs. The dominant orders of the spatial circumferential harmonics of the radial magnetic forces (RMFs) have been investigated and compared. The complete and complicated mechanical components, materials, and harmonics of the magnetic forces of the motor and their interaction are simplified and equalised to a vibration model, which consists of the interaction between the stator system and the dominant harmonic orders of the RMFs. Based on this approach, the simplest and most adequate semi-analytical-FEM model for noise prediction in PMSMs is proposed. This model, in addition to simplification, clarifies the role of the main mechanical and electromagnetic origins of noise generation. The acoustic noise prediction, using the proposed method has been compared with the experimental results. There is a proper agreement between the analytical, the FEM, and measurement results.

Assessing the insulation condition of oil-impregnated paper (OIP) bushings is necessary to guarantee the safe operation of power transformers. Moisture is the main threat to the insulation of OIP bushings. Therefore, accurately estimating their moisture value is crucial to keep power systems running smoothly. However, it has been suggested that the ageing status of OIP bushings should be considered while assessing the moisture. Dielectric frequency-domain spectroscopy (FDS) has been extensively employed for assessing insulation condition of OIP insulations due to its benefits. A new approach was proposed to assess the insulation condition of OIP bushings using FDS results. Various OIP samples with various moisture levels and degrees of polymerisation (DP) were selected. The extended Debye model (EDM) parameters related to each sample were calculated using their tanδ − f curve. A time constant database (TCD) was created using the obtained time constants of EDM, which includes the dominant time constant and time constant related to the R₀ – C₀ branch, and their corresponding insulation condition. Then, a method was introduced based on the created TCD to estimate the insulation condition of OIP bushings. The results showed that the average relative error of moisture and DP estimation is 8.33% and 6.32%, respectively.

Compared with a traditional low-speed high-torque permanent magnet synchronous motor (PMSM), a permanent magnet (PM)/reluctance hybrid rotor dual-stator synchronous motor (PM/RHRDSSM) has the advantages of high torque density and high space utilization. This type of motor is composed of a "back-to-back" PM + reluctance hybrid rotor and an inner and outer double stator. The number of poles of the inner and outer unit motors is the same, and the inner and outer stator windings are connected in series, driven by a single inverter. Due to the special mechanical structure and electromagnetic relationship of PM/RHRDSSM, traditional PMSM and synchronous reluctance motor maximum torque per ampere (MTPA) control strategies are no longer applicable. In response to this issue, the authors establishe a PM/RHRDSSM mathematical model of stator winding series structure and propose a MTPA control strategy suitable for this new type of motor. This strategy is aimed at the special mathematical model of PM/RHRDSSM and derives the analytical expression of MTPA trajectory, which minimises the required stator current amplitude of PM/RHRDSSM at various load torques, thereby minimising the motor copper loss. Finally, the effectiveness and practicality of the proposed control strategy were verified through simulation and experiments.

Soft magnetic lamination is produced with high width that usually is reduced by cutting. It yields permeability decreases Ɵ and loss increases r. So far, existing corresponding data is not consistent, since derived from strongly different lamination widths W. A consistent, ultra-rapid test method is suggested, for international standardisation. It is based on a multi-frequency single sheet tester. A 50 cm long, precisely prepared material sample of W = 17 cm is inserted into it, for an initial measurement in non-cut state. Then, it is cut into two 8.5 cm wide strips, for a test in cut state. Changes Ɵ and r are evaluated for induction values B up to 1.8 T. They are rapidly measured for frequencies of 50, 400 and 1000 Hz. Results from steel are described for guillotine cutting, from amorphous ribbon also for scissors. As a general tendency, Ɵ exceeds r by an order of about 3, however, with low reproducibility. Thus, standardisation is suggested for loss-rise functions r(B) only. Examples of r-functions reveal strong individual differences, as foot-prints of different products. With increasing f, r-values tend to sink. With increasing B, they rise, except for high B of NO steel. Amorphous ribbon shows non-clarified deviating tendencies. Standardisation of r-tests promises comparable information on cutting effects, for a given material, through a given cutting tool—but also on the tool's state of wear.

A rotor speed signature analysis- (RSSA-)based inter-turn short circuit (ITSC) fault diagnostic method is proposed, which is robust with regard to speed- and current-loop bandwidths of permanent magnet synchronous machine (PMSM) drive systems. Conventional ITSC fault detection solutions that rely on current signals or extra devices. Thus, an initial step of investigation on the validity of RSSA is taken for residual insulation capacity monitoring of the ITSC fault at the incipient stage. The Vold–Kalman filtering order tracking method is employed for the real-time extraction of fault features. Besides, the impact of speed- and current-loop controller bandwidths on ITSC fault diagnosis is also analysed and an Adaline estimator is designed to decouple their impacts. Finally, the effectiveness of the proposed method is verified on a faulty PMSM, which exhibits satisfying results in tracking the degradation of residual insulation, even if the phase currents are significantly distorted due to low switching frequency of the inverter.

High torque density and high reliability motors have a wide application prospect in aerospace field, so a hybrid rotor and dual stator motor is studied in this paper. Firstly, to address the problem that the difference in power density between the inner and outer unit motor is so large that it is not suitable for electromagnetic design using the power splitting method, a main dimensioning calculation method based on the equal-power volume transformation is proposed. The influence of thermal load on the output performance of the inner and outer unit motors is taken into account comprehensively. The main dimensioning expressions for such motors are derived. Secondly, the output performance consistency between the inner and outer unit motors is theoretically analysed, and the optimal angle between the d-axis of the permanent magnet rotor and the d-axis of the reluctance rotor is obtained when the motor is operated in the maximum torque per ampere control mode. Finally, a prototype with a rated power of 46.7 kW was developed and load experiments were conducted on it, and the experimental results verified the correctness and feasibility of the theoretical analysis method.

The oil cooling method has been widely used in the permanent magnet synchronous motor with hairpin winding. Because of the irregular shape of the hairpin end winding, there are complex oil circuits in the fluid domain, resulting in a large number of grids and a high computational cost. It is still a challenge to calculate the oil-cooling performance of the hairpin end winding. Therefore, the porous medium model (PMM) is first proposed to replace the real hairpin end winding to analyse the oil-cooling performance. By comparing oil volume fraction and velocity at different oil-supplied conditions using three methods: experiments, real model (the non-equivalent fluid domain model based on the real hairpin end winding) and PMM, the feasibility of using the PMM to calculate the oil-cooling performance on the end winding is verified. The oil distribution of three methods is the same. The use of the PMM saves 80% of the number of grids, which improves the simulation efficiency. Relationships between the porosity, permeability and resistance coefficient and the geometry parameters of windings are determined. The results show that the flow field changes greatly with changes in porosity, permeability and resistance coefficient.

In order to enhance the dynamic performance of aircraft high-voltage direct current wound rotor synchronous generator (WRSG) system under load variations, a dual internal model control (DIMC) method utilising improved load current feedback (ILCF) is proposed. It employs internal model controllers in both voltage and current loops, thereby significantly augmenting the system's disturbance rejection capabilities. Improved load current feedback is incorporated between the DC voltage loop and the field current loop. Additionally, a method for designing a feedback fitting function is established, enhancing the system's adaptability to changes in operational speed and load. The authors outline parameter design methods for voltage and current loops in DIMC, based on the internal model control principle. Adjustments to these parameters can further enhance the system's disturbance rejection capabilities. Finally, comparative experiments between the PI method with ILCF and the DIMC method with ILCF are conducted on a 15 kW WRSG experimental platform. These experiments demonstrate that the proposed DIMC method with ILCF optimises dynamic performance across the entire speed range, enhancing the competitiveness of WRSG systems in aircraft applications.