This study proposes an active neutral point clamped bidirectional multilevel converter, consisting of cascaded H-bridges fed by flying capacitors and T-type interconnections. It ensures any combination and polarity of flying capacitors in the current path, allowing a simple voltage balancing within the same voltage-pole. The flying capacitor voltages are scaled by factor of 2, enabling multiple switching vector combination for intermediate voltage-poles, as well as extending the number of voltage-poles. The suggested topology can reduce number of switches as compared to the counterparts. The framework also presents a method of balancing capacitor voltage. The feasibility and performance of the proposed solutions are verified by simulation results.

Bipolar DC grids are gaining great attention in modern power systems due to their superiority over Unipolar DC grids and AC grids. Existing studies on DC microgrid operations and controls individually investigate voltage control and balancing, power-sharing, and fault-tolerant operation. However, simultaneous investigation of voltage control, balancing, fault-tolerant operation and maximizing intermittence renewable energy in bipolar dc grids is important to understand the overall system behaviour. This paper presents a grid-connected bipolar DC microgrid architecture and control strategies to maximize the intermittence renewable energy usage, and reliable operation under fault conditions. The proposed DC microgrid can ensure reliable operation under healthy and faults conditions while utilising a high percentage of renewable energy, being verified through numerical results.

Significant amount of lately research is focused on improving performance of Darrieus type vertical-axis wind turbines (VAWT). This research explains the impact of rotor blade radius on tip-speed ratio, rotational frequency, starting wind speed, manufacturing costs and performance coefficient of Darrieus VAWT. To support the proposed explanations, a prototype with variable rotor blade radius was developed and tested in a wind tunnel. The conclusion is that blade radius should be decreased as much as possible until performance coefficient starts decreasing.

In this paper study of the effect of hybrid modulation on inductive-resonant wireless battery charger (in both constant current (CC) and constant voltage (CV) modes) performance characteristics (efficiency, conducted electromagnetic interference levels, etc.) is presented. The study is based on simulation of the wireless charger model in PSIM software. Performances of the wireless battery charger with the hybrid modulation are compared with that of the charger without modulations and with classical periodic switching frequency modulation. Additionally, some recommendations on selection of the hybrid modulation parameters are given. It is shown that the hybrid modulation is effective to improve performances of switching-frequency-modulated wireless battery chargers not only in CC charging mode, but also in CV charging mode.

In this paper spread spectrum technique based on switching frequency modulation for the first time is applied to closed-loop wireless power transfer (WPT) systems with multi level inverters at the primary side. The effect of switching frequency modulation on the main performance characteristics of WPT system with multi level inverter operating in constant current mode is studied thoroughly. The results show that the spread spectrum technique is useful approach for reduction of conducted electromagnetic emission generated by multilevel-inverter-based WPT system with moderate impact on other important performance characteristics provided that recommendations given are considered.

Shoot-through control methods for qZSI-based dc/dc converters are presented and studied. The major goal was to increase efficiency. A new modulation technique, pulse width modulation (PWM) with shifted shoot-through, is compared with the conventional PWM shoot-through control method. The new method reduces switching frequency of bottom side transistors and inherently features partial soft switching. Previous studies have shown that the biggest drawback of PWM control with shoot-through is unequal switching frequencies of transistors. One solution to that problem could be signal swapping that has been proposed by the authors of this paper. All control methods are first simulated and then experimentally verified on a test prototype.