Mark Edward Dame

A new family of active antiislanding schemes based on DQ implementation for grid-connected inverters

Unintentional islanding protection of distributed generation is a key function for standards compliance. For those distributed generations that use an inverter as grid interface, the function can be implemented as part of the inverter control. Existing antiislanding schemes used in inverters have power quality and nondetection zone issues. This paper proposes a new family of schemes that have negligible power quality degradation and no nondetection zone. Design guidelines based on frequency-domain analysis is also provided. Finally, both simulation and experimental results validate the proposed schemes.

A High Power Medium Voltage Resonant Dual Active Bridge for MVDC Ship Power Networks

This paper presents the design and control of a megawatt scale, medium voltage, medium frequency resonant dual active bridge dc–dc converter operating as a bus-tie converter in a dc distribution network. The high voltage (HV) side of the converter is designed using series connected low voltage (LV) devices to efficiently operate at higher switching frequencies. A combined variable frequency and phase-shift control method is proposed to achieve input–output power flow and voltage control, while maintaining soft switching operation for both the HV and LV bridges. Two 1 MW converter prototypes operated in a back-to-back arrangement are presented to validate the proposed topology and control.

A high power medium voltage resonant dual active bridge for DC distribution networks

This paper presents a megawatt scale, medium voltage, medium frequency resonant dual active bridge dc-dc converter operating as a bus-tie converter in a dc distribution network. The high voltage side of the converter is designed using series connected low voltage devices in order to efficiently operate at higher switching frequencies. A combined variable frequency and phase shift control method is proposed to achieve input/output power flow and voltage control, while maintaining soft switching operation for both high voltage and low voltage bridges. A 1MW converter prototype is presented to validate the proposed topology and control.

Development of Megawatt-Scale Medium-Voltage High Efficiency High Power Density Power Converters for Aircraft Hybrid-Electric Propulsion Systems

Hybrid-electric propulsion system is an enabling technology to make the aircrafts more fuel-saving, quieter, and lower carbide emission. In this paper, a megawatt-scale power converter based on a hybrid three-level active neutral-point-clamped (3L-ANPC) topology is developed. To achieve high efficiency, the switching devices operated at carrier frequency in the 3L-ANPC converter are configured by the emerging Silicon Carbide (SiC) Metal-Oxide Semiconductor Field-Effect Transistors (MOSFETs), while the conventional Silicon (Si) Insulated-Gate Bipolar Transistors (IGBTs) are selected for the switches modulated at the fundamental output frequency. The dc-bus voltage is increased from the conventional 270 V to 2.4 kV to reduce the power cable weight in the aircraft. Unlike the traditional 400 Hz aircraft electric systems, the rated fundamental output frequency of the inverter here is boosted to 1.4 kHz to drive the high-speed motor. Systematic hardware development and new PWM strategy for the 3L-ANPC inverter will be presented in this paper, and the associated experimental results are shown to verify the performance of this MW-scale medium-voltage inverter. It is shown that the 1-MW power inverter achieves an efficiency of99% and power density of 12 kVA/kg, which provides a promising solution to the realization of high-efficiency high-density aircraft hybrid propulsion systems.

Advancements in high power high frequency transformer design for resonant converter circuits

Medium and high frequency converters are gaining increasing interest for high power applications such as renewable energy and dc grids. Medium and high frequency transformers are an essential component in such converters. Advancing resonant converters to higher power levels challenges the transformer design in multiple aspects including power levels, switching frequency, ac and dc voltages insulation requirements and parasitic parameters. This paper presents design methods and recommendations for transformers that accomplish an industry-leading combination of power levels in the MW-class resonant frequencies up to 20kHz, operating AC voltages up to 5 kV, and dc offset voltages up to 300 kV. Design examples and test results of prototypes are presented along with results from applications where the transformers are integrated within high frequency converters.