The sunbeam can be converted into electricity via photovoltaic solar cells, and sun trackers are such devices for efficiency improvement. In this paper, different types of sun-tracking systems are reviewed, such as fixed tilt-angle, dual-axis, single-axis with East-West direction, and single-axis with North-South direction. The captured irradiation using different sun trackers are compared, and different influence factors are analyzed to gain the optimal orientation of the sun, such as time error, latitude, azimuth angle and tilt-angle of a photovoltaic module, reflectivity, and composite transparent coefficient. These results are very important to improve the tracking efficiency of the sun tracker.
The real‐time monitoring technology of power line is an important guarantee for the digitization and intelligence of the modern power system. Traditional current transformers cannot provide continuous and stable energy when the power line current fluctuates in a large range. This paper proposes a comprehensive design method of an active electronic current transformer (AECT) based on a single‐phase full‐bridge voltage‐type PWM rectifier (VSR), which can acquire continuous and stable energy from the power line with a minimum magnetic core. The control of the AECT is divided into four different operation modes to adapt the fluctuation of primary current. Maximum power point tracking (MPPT) mode and minimum loss (ML) mode is designed to harvest the maximum power with lower iron core loss when the primary current is relatively low. Excitation mode and demagnetization mode are designed to harvest stable power when the primary current is higher than a certain current. The specific mode operation principles and control strategies are analysed in detail. Besides, the calculation method of the primary current is also presented for the primary current measurement. Finally, simulations and experiments verify that the iron core can obtain power steadily (9.91 W/kg) when the current fluctuation between 50 and 600 A.
The switched capacitor converters have the advantages of high efficiency and high power density, which are widely used in data centers, distributed photovoltaic power generation, and other fields. In this paper, an optimized multi-modular resonant switched capacitor converter (MMRSCC) is proposed for an intermediate bus converter in the power supply system of data centers. By removing the inductance of part of the coupled resonant circuit, the converter can eliminate the influence of the parameter difference of passive components, and no additional voltage clamp circuit is needed, which improves the power density. At the same time, the half-bridge with the same switching action on the rectifier side is combined into one, which reduces the number of switching devices and is more conducive to improving the voltage conversion efficiency. In addition, the inductor of the basic unit of the resonant switched capacitor with the same state is shared to reduce the volume of the passive device, further improve the power density, and optimize the MMRSCC. Finally, the correctness of the topology is verified by simulation on the PLECS.
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