This paper presents a modulation strategy for wide voltage output in a bidirectional modular multilevel dc-dc power electronic converter for wave energy extraction using Electro Active Polymer Wave Energy Converters (EAPWECs). The chosen electrical power converter uses a 10 kV, low current bidirectional dc-dc modular multilevel topology with Dual Active Bridges (DABs) as a basis for each module. This paper proposes a modulation method consisting of several variable frequency DAB modulation modes and explains their operating areas and limitations. Through a simulation model it is shown how the control for the multilevel converter is implemented. Finally, loss estimation is performed using the developed loss model, which was previously validated on an experimental setup.

This paper presents a novel Modular Multilevel DC-DC Converter (M2DC) topology capable of providing high voltage to electrostatic renewable energy converters. Electrostatic energy converters potentially offer high system reliability because they eliminate the need for a mechanical energy conversion interface, but high voltage in the range of 2.5–100 kV is required for their operation. The main feature of the M2DC topology is that it uses a secondary power loop to balance module capacitor voltages. The M2DC is compared with an existing solution for the same energy harvesting application showing advantages in isolation requirements and the number of switch gate drivers and magnetic components. Simulation results show that the M2DC topology is promising. Furthermore, utilization of the M2DC topology is not limited to electrostatic renewable energy converters, but also can, for example, be used in dc transmission systems.

Previous methods for measuring magnetic core loss are either only suitable for sine wave excitations or cannot separate winding loss from inductor loss. In this paper, we present a new method to distinguish winding loss from inductor loss under practical excitations. This method utilizes a converter to generate the actual excitation waveforms and uses a calorimetric setup to quantify the losses. By splitting up the inductor in a converter into an air core inductor and a magnetic core inductor, both equipped with exactly the same winding structure, the air core inductor loss can be used as the reference of the magnetic cored inductor winding loss. In this way, magnetic core losses can be determined in the actual operation condition of a converter in which the inductor is to be used. The method requires simple setup and is easy to execute. It worked well in assessing different magnetic core materials.

Historically, it came about that the analysis and design of the power electronic converter center around currents and voltages in the circuits. During the last decade, the electromagnetic character of power electronic converters became more important due to the noise that the switches generate, and electromagnetic interference (EMI) and electromagnetic compatibility (EMC) standards have been put in place to control the electromagnetic noise levels. In this contribution, it is argued that coming to grips with the electromagnetic operation of switch-mode power conversion presents a barrier of knowledge that will have to be crossed in order to achieve future meaningful innovation in switch-mode power conversion. Rigorous electromagnetic analysis using realistic parameters are used to indicate important issues relating fundamental limits and technological paths for future generations of power electronic converters. Electromagnetic integration in three dimensions creates new possibilities to increase power densities.