Advanced wind energy convertors using electronic power conversion.

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On-line Condition Monitoring, Fault Detection and Diagnosis in Electrical Machines and Power Electronic Converters

The objective of this PhD research is to develop robust, and non-intrusive condition monitoring methods for induction motors fed by closed-loop inverters. The flexible energy forms synthesized by these connected power electronic converters greatly enhance the performance and expand the operating region of induction motors. They also significantly alter the fault behavior of these electric machines and complicate the fault detection and protection. The current state of the art in condition monitoring of power-converter-fed electric machines is underdeveloped as compared to the maturing condition monitoring techniques for grid-connected electric machines. This dissertation first investigates the stator turn-to-turn fault modelling for induction motors (IM) fed by a grid directly. A novel and more meaningful model of the motor itself was developed and a comprehensive study of the closed-loop inverter drives was conducted. A direct torque control (DTC) method was selected for controlling IM’s electromagnetic torque and stator flux-linkage amplitude in industrial applications. Additionally, a new driver based on DTC rules, predictive control theory and fuzzy logic inference system for the IM was developed. This novel controller improves the performance of the torque control on the IM as it reduces most of the disadvantages of the classical and predictive DTC drivers. An analytical investigation of the impacts of the stator inter-turn short-circuit of the machine in the controller and its reaction was performed. This research sets a based knowledge and clear foundations of the events happening inside the IM and internally in the DTC when the machine is damaged by a turn fault in the stator. This dissertation also develops a technique for the health monitoring of the induction machine under stator turn failure. The developed technique was based on the monitoring of the off-diagonal term of the sequence component impedance matrix. Its advantages are that it is independent of the IM parameters, it is immune to the sensors’ errors, it requires a small learning stage, compared with NN, and it is not intrusive, robust and online. The research developed in this dissertation represents a significant advance that can be utilized in fault detection and condition monitoring in industrial applications, transportation electrification as well as the utilization of renewable energy microgrids. To conclude, this PhD research focuses on the development of condition monitoring techniques, modelling, and insightful analyses of a specific type of electric machine system. The fundamental ideas behind the proposed condition monitoring technique, model and analysis are quite universal and appeals to a much wider variety of electric machines connected to power electronic converters or drivers. To sum up, this PhD research has a broad beneficial impact on a wide spectrum of power-converter-fed electric machines and is thus of practical importance

Design and Realization of a Bidirectional EV Battery Charger for V2G and G2V purposes

The continuous development of electric drive systems and battery technology has made the Electric Vehicle technology (EV) a more competitive option in the market with conventional vehicles. Among other merits, EVs can also provide ancillary services to support the grid (acting as controlled loads or energy storage units) in order to provide supply/demand matching to level the daily load profile and contribute to voltage and frequency controlopenEmbargo per motivi di segretezza e/o di proprietà dei risultati e/o informazioni sensibil

Power Converters in Power Electronics

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical sciences. Power converters, in the realm of power electronics, are becoming essential for generating electrical power energy in various ways. This Special Issue focuses on the development of novel power converter topologies in power electronics. The topics of interest include, but are not limited to: Z-source converters; multilevel power converter topologies; switched-capacitor-based power converters; power converters for battery management systems; power converters in wireless power transfer techniques; the reliability of power conversion systems; and modulation techniques for advanced power converters

Design and Control of Power Converters 2020

In this book, nine papers focusing on different fields of power electronics are gathered, all of which are in line with the present trends in research and industry. Given the generality of the Special Issue, the covered topics range from electrothermal models and losses models in semiconductors and magnetics to converters used in high-power applications. In this last case, the papers address specific problems such as the distortion due to zero-current detection or fault investigation using the fast Fourier transform, all being focused on analyzing the topologies of high-power high-density applications, such as the dual active bridge or the H-bridge multilevel inverter. All the papers provide enough insight in the analyzed issues to be used as the starting point of any research. Experimental or simulation results are presented to validate and help with the understanding of the proposed ideas. To summarize, this book will help the reader to solve specific problems in industrial equipment or to increase their knowledge in specific fields

A fast remotely operable digital twin of a generic electric powertrain for geographically distributed hardware-in-the-loop simulation testbed

The automotive industry today is seeing far-reaching and portentous changes that will change the face of it in the foreseeable future. Digitalisation and Electrification are two of the key megatrends that is changing the way vehicles are developed and produced. A recent development in R&D process is the Hardware-in-the-Loop (HIL) method that uses a hybrid approach of testing a physical prototype immersed in a virtual environment, which is nowadays being creatively re-applied towards geographically separated multi-centre testing strategies, that suits the horizontally integrated and supply-chain driven industry very well. Geographical separation entails the deployment of a “Digital Twin” in remote centre(s) participating in multi-centre testing. This PhD aims to produce a highly robust, efficient, and rapidly computable Digital Twin of a generic electric powertrain using the multi-frequency averaging (MFA) technique that has been extended for variable frequency operation. This PhD also aims to commission a local HIL simulation testbed for a generic electric power inverter testing. The greater goal is to co-simulate the local HIL centre testing a prototype inverter, and its Digital Twin in a different location “twinning” the prototype inverter as best as possible. A novel approach for the Digital Twin has been proposed that employs Dynamic Phasors to solve the system in the frequency domain. An original method of multiplication of two signals in the frequency domain has been proposed. The resultant model has been verified against an equivalent time domain switching model and shown to outperform appreciably. A distinctive advantage the MFA Digital Twin offers is the “fidelity customisability”; based on application, the Twin can be set to compute a low (or high)-fi model at different computational cost. Finally, a novel method of communicating high-speed motor shaft position information using a low-speed processing system has been developed and validated. This has been applied to run real-life HIL simulation cycles on a test inverter and effects studied. The two ends of a multi-HIL testbed, i.e., local HIL environment for an inverter, and its Digital Twin, has been developed and validated. The last piece of the puzzle, i.e., employing a State Convergence algorithm to ensure the Digital Twin is accurate duplicating the performance of its “master”, is required to close the loop. Several ideas and process plans have been proposed to do the same

Modular multilevel converter with embedded batteries as a motor controller.

This thesis details the design of the control system and hardware for a prototype of the new inverter topology the modular multilevel converter with embedded batteries for electric vehicle applications. Within this topology, the battery cells incorporated within the battery pack are directly integrated into the motor controller/ power converter by replacing the individual module capacitors with batteries. Since the batteries are directly connected to the module switching circuit, the batteries can be individually balanced using the same technique as an active battery management system, without the need for external energy-shunting hardware. A control algorithm for balancing the embedded batteries without affecting the motor control scheme with significantly unbalanced battery cells is presented and discussed. A multilevel space vector modulation scheme using the abc-reference frame for the selection of space vectors is developed. Initial testing of both the simulation model and prototype was carried out using a static RL load to test the PWM scheme and battery SOC balancing scheme. A Field-oriented control scheme was then designed and implemented for controlling a salient pole surface-mounted PMSM. The performance of the converter as a motor controller was assessed in terms of ability to balance the SOC of the embedded module batteries and total harmonic distortion over the course of the operating torque-speed range. Simulation of the control system on simulated hardware has been carried out in MATLAB; these simulation results verify the theoretical analysis. Then further verified and analysed using the developed laboratory-scale embedded battery MMC prototype