±35 kV/500 kW DC Grid-Connected Modular IPOS Converter for PV Power Generation

In Chap. 1, it is pointed out that the application of modular IPOS converter in high-power occasions helps to reduce the development difficulty and cost, and shorten the development cycle of the system. Among different submodule converters, LLC resonant converter has the advantages of ZVS turn-on for primary switches and ZCS turn-off for secondary switches in the full load range. Besides, this converter offers excellent EMI characteristics, realizing higher efficiency and power density, making it widely applicable in various dc/dc conversion occasions. The input series output series (ISOS) or input series output parallel (ISOP) converters have been well studied in literature, while there are few studies on unidirectional dc/dc converters with high step-up ratio and high efficiency suitable for DC grid-connected PV power generation. Therefore, with the funding support of the project of “Key Technologies and Equipment of DC Step-Up Power Collection and Integration for Large-scale PV Station”, this chapter investigates the key parameter design, component selection, voltage- and current-sharing characteristics, startup strategy. Experimental verification of the ±35 kV/500 kW DC grid-connected modular IPOS converter is also provided, where the LLC converter is adopted as the submodule.