POWER INTERFACES AND STORAGE SELECTION FOR AN ULTRAFAST EV CHARGING STATION

The paper is a summary of the research conducted so far on the ultrafast charging issues of electric vehicles with the main emphasis on the infrastructure. In order to estimate the load curve and peaks resulting from high charging rate, simulations are carried out initially to determine energy and power ratings. Energy storage options for filtering out the perspective peaks are discussed with applicable power interfaces between the grid, the vehicle and the storage buffer. Finally, an ultrafast charging architecture based on cascaded H-bridge converters is proposed.

Power and DC Link Voltage Control Considerations for Indirect AC/AC Modular Multilevel Converters

A highly interesting application field of the Modular Multilevel Converter is the interconnection of the European three-phase 50 Hz industrial grid with the single-phase 16 2/3 Hz railway supply. Contrary to existing technologies, the utilization of a bulky and costly transformer on the low frequency side as well as additional filtering components on the AC lines or DC link are avoided. However, the inherent converter dynamics still pose challenges in the design of control systems, which should ensure safe operation as well as high performance in steady state and transient conditions. This paper investigates an eective way to control the power as well as the DC link voltage in such a Modular Multilevel Converter-based network interface. The additional control objectives, such as branch energy stabilization as well as sub-module capacitor voltage balancing are maintained, regardless of the aforementioned externally controlled magnitudes. The DC link second harmonic power fluctuation, which is a property of the single-phase side, is also compensated by means of proper circulating current control. The analyzed concepts are evaluated by means of simulation results, using a discrete-time model of a real power application

Model predictive-based control method for cascaded H-bridge multilevel active rectifiers

The cascaded H-Bridge multilevel active rectifier is an emerging converter topology, which offers significant advantages, such as modularity and high flexibility for a wide range of applications, including traction systems, industrial automation plants, uninterruptable power supplies, and battery chargers. However, the need for stable operation of the H-Bridge cells at asymmetrical voltage potentials and unbalanced loads imposes demanding requirements, in terms of an advanced and accurate control strategy. This paper introduces a simple and powerful solution to the mentioned problems, based on constrained Model Predictive Control (MPC). The proposed nonlinear controller achieves low input current harmonic distortion with almost unity power factor, as well as independent regulation of the H-Bridge cells, both under steady state and transient conditions. The effectiveness of the novel control algorithm is demonstrated by means of simulations as well as preliminary experimentation on a single-phase laboratory setup

A Versatile DC-DC Converter for Energy Collection and Distribution using the Modular Multilevel Converter

The drawbacks of conventional Modular Multilevel Converters (MMC) are described in terms of short-circuits. The configuration of MMC-transformer-MMC proves to handle short-circuits at the input and output without the need for additional DC or AC circuit breakers for protection. The transformer can be operated with a higher frequency, reducing therefore the size of the transformer and the capacitors considerably. A multitude of input and output configurations are possible, AC/AC, AC/DC and DC/DC. In particular a DC/DC structure is analysed, serving as DC circuit breaker and voltage elevation interface at the same time. The control strategy of the DC/DC converter is described and an experimental prototype validates the proposed structure and control