Static Eccentricity Fault Detection in Brushless Doubly Fed Induction Machines based on MotorCurrent Signature Analysis

In this paper a new rotor eccentricity fault detection method is proposed for the first time for Brushless Doubly Fed Induction Machines (BDFIMs). Due to the fact that BDFIMs are attractive alternatives to doubly fed induction machines for wind power generation, paying attention to their fault diagnosis is essential. Existing fault detection methods for conventional induction machines can not be directly applied to the BDFIM due to its special rotor structure and stator winding configurations as well as the complex magnetic fields. In this paper a new fault detection technique based on stator current harmonic analysis is proposed to detect rotor eccentricity faults in the BDFIM. The validity of the proposed fault detection method is verified by analytical winding function method and finite element analysis on a prototype D180 BDFIM. Index Terms—Brushless doubly fed induction machines, Nested-loop rotor slot harmonics, Motor current signature analysis, Winding function method, Finite element analysis, Static eccentricity fault

Design of rotatory transformer for wireless power transfer in the X-rotor wind turbine

Operation and Maintenance (O&M) of offshore wind turbines is, by far, the largest cost element of the levelized cost of energy (LCOE) of an offshore wind farm project [1]. The quest for reducing the LCOE has led to the recent deployment of the EU-funded X-rotor project [2]. The X-rotor is a novel hybrid wind turbine that retains some of the advantages of Vertical-Axis Wind Turbines [3]. A key feature of the X-rotor is the use of secondary rotors, mounted in a X-shaped vertical axis structure. One requirement in the X-rotor operation is the capacity to transfer the power generated by secondary rotors from a rotating structure to the turbine tower. Given the well-documented impact of slip-rings in offshore wind turbine O&M [4], the necessity of MW-level wireless power transfer (WPT) arises to retain the advantages of the X-rotor system. This research focuses in the magnetic design and finite element simulation/verification of a MW-level, medium-frequency Rotary Transformer (RT) interfaced by a 3-phase (3-hp) dual-active-bridge (DAB) converter for WPT. The research presents the design of a rotary transformer and the selection of the parameters such as operating frequencies, current density, windings area, air-gap length, and others for the proper functioning of the system. The efficiency is quantified using finite element simulation and numerical calculations. Furthermore, its thermal performance at rated power levels is analysed and quantified using finite element simulation. Furthermore a 3 phase dual active bridge power electronic topology for the rotary transformer is used to manipulate the wireless power flow at the levels of efficiency required by the XROTOR project. The analysis of the topology includes electrical operation and energy conversion losses. Results indicate that the combined efficiency of the rotary transformer with its associated power electronic converter turned to be 96.53% for a 1MW system

Fault diagnosis and condition monitoring in wave energy converters : a review

The technology used in wave energy conversion systems is still in the early stages of research and development. There are a number of challenges associated with becoming a commercially viable source of renewable energy due to the high operating and maintenance (O&M) costs. A potential solution for increasing the availability of wave energy converters (WECs) and reducing operating and maintenance costs might involve the implementation of condition monitoring and fault-tolerant control systems, because in some reported WEC systems, 57% of total operational expenses go to maintenance activities. The use of condition monitoring techniques in wind energy systems has, for instance, shown the ability to detect failures months in advance, resulting in savings of 15–20% during the operational phase. This paper reviews the methods proposed (and some used) by researchers to monitor WEC’s condition and diagnose faults. Fault-tolerant control methods developed to improve the reliability of WECs and hence their commercial viability are also reviewed and discussed. In addition, a future research plan is provided here

Design and analysis of a 100kW rotary transformer for XROTOR wind generators

This paper presents a design methodology for a high power rotary transformer solution for novel offshore X-rotor wind turbine. The design methodology is studied for both in 2D and 3D finite element method for a 100KW system. The results of current, voltage, output power and magnetic field in 2D model is the same as 3D model. The results verify the design methodology, and that efficiency is high enough to present the rotary transformer solution as an alternative for slip rings in the novel X-rotor wind turbine design. Also, the sensitivity analysis has been performed to show the effect of some important parameters

An integrated rotary transformer and 3-phase dual-active-bridge converter for high power transfer in novel X-rotor wind turbines

The slip ring solution for power transfer between rotating structures has adverse impact the maintenance of offshore wind turbines. In this paper the design, performance, efficiency, and manufacturing details of a 1 MW wireless power transfer system for the novel X-rotor offshore wind turbine concept is presented. The results show that this design methodology that includes rotary transformers and dual active bridge converters is suitable for high-efficiency high-power wireless transfer systems

High Frequency, High Efficiency, and High Power Density GaN-Based LLC Resonant Converter: State-of-the-Art and Perspectives

Soft switching for both primary and secondary side devices is available by using LLC converters. This resonant converter is an ideal candidate for today’s high frequency, high efficiency, and high power density applications like adapters, Uninterrupted Power Supplies (UPS), Solid State Transformers (SST), electric vehicle battery chargers, renewable energy systems, servers, and telecom systems. Using Gallium-Nitride (GaN)-based power switches in this converter merits more and more switching frequency, power density, and efficiency. Therefore, the present paper focused on GaN-based LLC resonant converters. The converter structure, operation regions, design steps, and drive system are described precisely. Then its losses are discussed, and the magnets and inductance characteristics are investigated. After that, various interleaved topologies, as a solution to improve power density and decrease current ripples, have been discussed. Also, some challenges and concerns related to GaN-based LLC converters have been reviewed. Commercially available power transistors based on various technologies, i.e., GaN HEMT, Silicon (Si) MOSFET, and Silicon Carbide (SiC) have been compared. Finally, the LLC resonant converter has been simulated by taking advantage of LTspice and GaN HEMT merits, as compared with Si MOSFETs