SVPWM zero-sequence voltage elimination for the dual fed common dc-link open-end winding PMSM high-speed starter-generator

The dual-inverter topology has been widely investigated for Open-End Winding (OEW) machines such as induction motors and Permanent Magnet Synchronous Motors (PMSMs). The extensive work done on this topology showed that three-level inversion can be realized with two two-level inverters connected at each end of the machine terminals. Furthermore the dual-fed OEW topology allows for increased fault-tolerant capability, reduction of the dc-link voltage by half and redundant space-vector combinations. In this PhD work, a dual-inverter made of a Si-based 3ph full-bridge converter and one SiC-based 3ph full-bridge connected across the same dc link has been used to drive an high-speed starter-generator OEW-PMSM for aerospace application. The mixed technology dual-inverter allows to achieve higher system efficiency by exploiting the different nature of the two Voltage Source Converters (VSCs). While on one hand the common dc bus configuration significantly simplifies and reduces the costs of the topology, on the other hand it allows the Zero-Sequence Current (ZSC) to flow freely in the system. Previous work focused on the study of modulations which aim to either reduce or control the average Zero-Sequence Voltage (ZSV) on the controller sample time. The low phase inductance, which characterizes high speed machines implies low Zero-Sequence Impedance (ZSI). Therefore any ZSV applied to the zero-sequence circuit would result in a high frequency, high intensity ZSC ripple with the risk of harming the switching devices. This work presents a novel hybrid Space Vector Pulse Width Modulation (SVPWM) that allows to instantaneously eliminate the ZSV produced by the dual-inverter by square wave modulating the IGBT VSC. The non-sinusoidal machine’s back Electro Magnetic Force (backEMF) has been considered and the effect of the converters Dead Time (DT) on the ZSV has been analysed. Since the ZSV generated by the dual-inverter causes high ZSC to circulate in the machine, the voltage distortion introduced by the DT has been considered as a possible control action to eliminate the ZSC flowing due to the non-sinusoidal machine’s back-EMF. A novel SVPWM for instantaneous ZSV elimination and a zero-sequence DT hysteresis controller have been investigated and experimentally tested both on a scaled-down OEWM and the full-scale high-speed starter-generator prototype

Oversampled deadbeat current control strategy for PMSM drives

This paper presents a novel deadbeat current control approach for Permanent Magnet Synchronous Motors (PMSMs) drives capable of operating at a controller sampling frequency multiple of the power converter switching frequency. The proposed technique permits to achieve a constant switching frequency and an optimal current ripple along with a high current loop bandwidth and robust behaviour to parameter variation

Electric Drive Based on an Open-End Winding Surface PM Synchronous Machine with a Floating Capacitor Bridge

A speed control scheme is presented for a 3-phase surface permanent magnet synchronous machine with an openend stator winding fed by a three-phase inverter and a floating bridge inverter. The latter is used to compensate for the reactive power of the main inverter and to maximize the active power received by the motor, without exceeding the available stator current and DC-link voltage. To reduce the switching losses, the DC-link voltage of the floating inverter bridge varies depending on the operating condition of the motor and the controllability requirements of the system. The experimental results show that a significant improvement in the speed range at constant power is achievable, proportionally to the DC-link voltage of the floating bridge inverter

Sensorless finite-control set model predictive control for IPMSM drives

This paper investigates the feasibility of a sensorless field oriented control (FOC) combined with a finite control set model predictive current control (FCS-MPC) for an interior permanent magnet synchronous motor (IPMSM). The use of a FCS-MPC makes the implementation of most of the existing sensorless techniques difficult due to the lack of a modulator. The proposed sensorless algorithm exploits the saliency of the motor and the intrinsic higher current ripple of the FCS-MPC to extract position and speed information using a model-based approach. This method does not require the injection of additional voltage vectors or the periodic interruption of the control algorithm and consequently it has no impact on the performance of the current control. The proposed algorithm has been tested in simulation and validated on an experimental set-up, showing promising results

Terahertz Nanoantennas for Enhanced Spectroscopy

Terahertz spectroscopy has great potential for sensing a wide range of elementary excitations. However, terahertz studies are practically limited to macroscopic ensembles of compounds (e.g., thick pellets of crystallized molecules or highly concentrated solutions of nanomaterials) due to the long radiation wavelength (about 300 μm at 1 THz). In this chapter, we show how terahertz nanoantennas can overcome the current limitations of terahertz spectroscopy such as low sensitivity and low spatial resolution. We briefly discuss how to design the resonance characteristics of a dipole nanoantenna through a Fabry-Pérot model, and then we present the experimental characterization of the spectral response of ordered arrays of such devices. Furthermore, we demonstrate how nanoantenna arrays enable the possibility of retrieving the spectroscopic signature of a monolayer of quantum dots and, in principle, of many other organic or inorganic compounds. This technique, based on the idea of increasing the sensitivity through local field enhancement, is named nanoantenna-enhanced terahertz spectroscopy (NETS). A Fano-like interference between the fundamental mode of the nanoantennas and the phonon resonance of the quantum dots is observed, together with an enhancement of the absorption of the dots up to more than a million. Finally, we show how to extract the main spectroscopic information of the quantum dots through a simple coupled harmonic oscillator model. This novel technique can be widely applied in terahertz spectroscopic studies of nanocrystals and molecules, where extremely low concentrations are of concern

Asset Administration Shell as an interoperable enabler of Industry 4.0 software architectures: a case study

In recent years, the discipline of Digital Transformation in manufacturing companies turned out to be a hot topic of research debate, which allowed the design and introduction of new technologies and tools able to exploit the potential of the data produced by the shop floor assets. This increased interest in data generation and management has however highlighted a crucial issue about the lack of standardised models and structures to share these data and ensure interoperability. Among the several concepts proposed by the recent initiatives devoted to solving or mitigating this issue, Asset Administration Shell (AAS) is increasing in popularity, given its potential in providing standardised and modular information about the assets and events represented. This paper deals with a demonstration of the easiness of integration of AAS in pre-existing software architecture, allowing higher flexibility and a better understanding of the ongoing processes: a production line has been indeed entirely represented with modular AAS metamodels and it has been used to feed a Digital Model representing the line configuration. The use case proposed proves the effectiveness of the obtained solution when used for virtual commissioning operations

IGBT-SiC dual fed open end winding PMSM drive

This paper proposes a dual fed common dc link inverter Open End Winding-Permanent Magnet Synchronous Motor (OEW-PMSM) Drive. In order to increase the system efficiency a dual technology converter is used, with one inverter composed of standard IGBT devices and the other composed of fast switching Silicon Carbide (SiC) devices. The common dc link OEW configuration allows the zero-sequence current (ZSC) to flow freely, and the low time constants of the zero-circuit can lead to high zero sequence current flow, with associated losses and stress on the power devices. To avoid this, the zero-sequence voltage produced by the switching combinations adopted to synthetize the control signals needs to be instantaneously eliminated. A novel modulation for dual converter configurations is proposed to eliminate the zero-sequence voltage(ZSV)

IGBT-SiC dual fed ground power unit

This paper presents the design and control of a three-phase ground power supply unit for aircraft servicing. A new mixed technology converter composed by a three-phase Silicon Carbide (SiC) full bridge unit and a three-phase full bridge IGBT unit connected across the same dc link is used instead of the conventional full bridge configuration. In order to satisfy the stringent requirements of the output voltage quality particular attention is given to the controller. The common dc link topology of the converter allows circulation of Zero Sequence Current (ZSC), therefore also a 0 axis regulator is necessary. The state space model of the system considering the LC output filter is presented and used in order to synthetize the controller parameters using the Optimal Control theory

FPGA Implementation of a Novel Oversampling Deadbeat Controller for PMSM Drives

This paper presents a novel oversampling deadbeat current control approach for permanent magnet synchronous motor drives capable of operating at a controller sampling frequency multiple of the power converter switching frequency. Model-based controllers suffer from heavy computational demand and performance degradation due to parameter uncertainties. The proposed controller concurrently with field-programmable gate array implementation permits to achieve a constant switching frequency and an optimal current ripple along with a high current-loop bandwidth and robust behavior to parameter variation. A disturbance observer has been added to the proposed controller in order to compensate for the converter voltage distortions. The proposed control strategy is tested through both simulations and experiments

An innovative index to incorporate transcriptomic data into weight of evidence approaches for environmental risk assessment

The sharp decrease in the cost of RNA-sequencing and the rapid improvement in computational analysis of eco-toxicogenomic data have brought new insights into the adverse effects of chemicals on aquatic organisms. Yet, transcriptomics is generally applied qualitatively in environmental risk assessments, hampering more effective exploitation of this evidence through multidisciplinary studies. In view of this limitation, a methodology is here presented to quantitatively elaborate transcriptional data in support to environmental risk assessment. The proposed methodology makes use of results from the application of Gene Set Enrichment Analysis to recent studies investigating the response of Mytilus galloprovincialis and Ruditapes philippinarum exposed to contaminants of emerging concern. The degree of changes in gene sets and the relevance of physiological reactions are integrated in the calculation of a hazard index. The outcome is then classified according to five hazard classes (from absent to severe), providing an evaluation of whole-transcriptome effects of chemical exposure. The application to experimental and simulated datasets proved that the method can effectively discriminate different levels of altered transcriptomic responses when compared to expert judgement (Spearman correlation coefficient of 0.96). A further application to data collected in two independent studies of Salmo trutta and Xenopus tropicalis exposed to contaminants confirmed the potential extension of the methodology to other aquatic species. This methodology can serve as a proof of concept for the integration of “genomic tools” in environmental risk assessment based on multidisciplinary investigations. To this end, the proposed transcriptomic hazard index can now be incorporated into quantitative Weight of Evidence approaches and weighed, with results from other types of analysis, to elucidate the role of chemicals in adverse ecological effects