Series phase-shifted full-bridge DC-DC converters in a new type of full scale photovoltaic DC power generation system

摘要

At present, traditional photovoltaic power plants use AC system as the main network structure, which is mature and reliable. However, AC structure has obvious disadvantages. On the one hand, there are a lot of traditional low-voltage converters in the main grid. On the other hand, the line loss increases a lot due to the low line voltage of AC system. In the investigation we described here, we proposed a new type of full scale Photovoltaic DC Power Generation System. The station bus in the system was high-voltage DC bus and made of the high-power phase-shifted full-bridge DC-DC modules to realize the maximum power point tracking. And the high voltage of DC bus was built by the series of DC-DC converter modules. The DC bus structure was helpful to decrease the line loss. At the same time, the phase-shift converter, to which the technology of Zero Voltage Switch can apply, help to reduce the switching loss and increase the operation efficiency. This paper concerned about the series Phase-shifted full-bridge DC-DC converters in the new type of full scale Photovoltaic DC Power Generation System. In the investigation we discussed here, we simulated a single 100kW Phase-shifted full-bridge module to trace the maximum power point. We focused on the distribution of capacitor voltage in series DC-DC modules. At the same time, much research about transition process and response when some modules worked out or the PV characteristics changed had been done in the paper.