Thin-film-integrated power inductor on Si and its performance in an 8-MHz buck converter

This paper presents a microinductor fabricated on silicon using electrochemical techniques that has high efficiency in a low power dc–dc converter. Small signal measurements show a flat frequency response up to 20 MHz with a self resonant frequency of 130 MHz. The inductance at low frequency is approximately 440 nH with a dc resistance of 0.5 Ω, and a high quality factor of 11.7 at 5.5 MHz. The current handling capability test shows less than 10% decrease in inductance at 500-mA current. The performance of the microinductor has been compared to a conventional chip inductor in a commercially available 8-MHz buck converter. The converter maximum efficiency when using the microinductor is shown to be approximately 3% lower than the one using the conventional discrete chip inductor. However, the profile of the microinductor is much lower than that of the discrete chip inductor. The maximum efficiency of the microinductor in the converter is estimated to be approximately 92%

VSC-HVDC link to support voltage and frequency fluctuations for variable speed wind turbines for grid connection

2012 3rd IEEE PES Innovative Smart Grid Technologies Europe (ISGT Europe), , Berlin, GermanyThis paper presents the use of induction generator turbine machines with simplified frequency control as a direct drive solution for wind energy conversion. An offshore wind farm system is proposed utilising a VSC-HVDC connection. The wind farm will contain variable speed wind turbines driving Squirrel Cage Induction Generators (SCIG). The study will look at the electrical performance of the generators with real wind data and the design control implications with a VSC-HVDC link. The performance of the system is verified by computer simulation using the Dymola/Modelica software platform with the ObjectStab power systems analysis toolbox. This paper presents the design of independently developed optimised power system models for variable speed wind turbine machines with simplified pitch angle and frequency control with a VSC-HVDC link for grid interconnection.Science Foundation IrelandDeposited by bulk impor

Design of VSC Connected Low Frequency AC Offshore Transmission with Long HVAC Cables

Low frequency ac transmission (LFAC) has been proposed as an alternative to high voltage dc transmission for medium distance (80-150 km) offshore wind farms. Long HVAC cables and their associated low frequency resonance, connected to voltage source converters (VSC), provide technical challenges for the control of the offshore voltage. This paper provides the design of the offshore voltage 'grid forming control' to maintain a stable offshore voltage accounting for the connection of a long HVAC cable connected to the VSC. Simulations are performed on an LFAC test system to examine the influence of controller parameters and the associated design tradeoffs between the selection of dq controller time constants and voltage control bandwidth. The LFAC system design and control is then validated in a hardware experiment where the proposed controller operates in a real-Time hardware-in-The-loop experiment.Science Foundation IrelandUniversity College DublinElectricity Research Centre, University College Dubli

Harmonic stability of VSC connected Low Frequency AC offshore transmission with long HVAC cables

Low Frequency AC (LFAC) transmission has been proposed as an alternative to HVDC transmission for the integration of offshore wind. The LFAC offshore grid as a fully power electronic grid with a long HVAC cable provides significant challenges to harmonic stability. This paper presents an impedance based stability analysis to determine the stability of the power electronic offshore system across the harmonic frequency range. The stability analysis is introduced and applied to the LFAC system. The impact of different current and voltage control bandwidths and component sizes on the dynamic impedance of the converters is then examined and their impact on harmonic stability of the LFAC grid is determined. It is found that detailed knowledge of the control parameters and the ability to tune the bandwidths can mitigate significant harmonic instability with the presence of a long HVAC cable. Three phase simulations are then used to validated the impedance based stability technique.Science Foundation Irelan

Harmonic stability of VSC connected Low Frequency AC offshore transmission with long HVAC cables

Low Frequency AC (LFAC) transmission has been proposed as an alternative to HVDC transmission for the integration of offshore wind. The LFAC offshore grid as a fully power electronic grid with a long HVAC cable provides significant challenges to harmonic stability. This paper presents an impedance based stability analysis to determine the stability of the power electronic offshore system across the harmonic frequency range. The stability analysis is introduced and applied to the LFAC system. The impact of different current and voltage control bandwidths and component sizes on the dynamic impedance of the converters is then examined and their impact on harmonic stability of the LFAC grid is determined. It is found that detailed knowledge of the control parameters and the ability to tune the bandwidths can mitigate significant harmonic instability with the presence of a long HVAC cable. Three phase simulations are then used to validated the impedance based stability technique.Science Foundation Irelan