Soft-switched high-frequency power converters for energy systems

随着能源需求的增加和对环境的关注，替代能源(燃料电池、风能、光伏和海洋)正变得流行起来。这些能源的产出差别很大，包括一些运行限制。一些例子是：(1)燃料电池产生变化很大的低压直流(例如，22至41V)，对负载变化的瞬时响应较慢，并且在纹波电流下性能下降。(2)用于风力发电机组的永磁同步发电机产生可变电压和频率的交流输出，需要经过功率因数(PF)校正的AC/DC转换器才能获得稳定的直流母线。对于所有这些电源，独立或公用接口都需要一个额外的DC/AC转换器来增强发电量。此外，当不同的能源连接到DC母线时，需要双向DC-DC转换器来为电池充电以及为DC母线供电，而用于为燃料电池产生氢气的电解器需要DC/DC转换器。因此，所有这些能源都需要低成本、高效率的DC/DC、DC/AC和AC/DC电力电子转换器，同时满足能源的约束。使用低损耗和高开关频率的软开关(包括谐振)转换器可以实现这一点。这些转换器具有效率高、体积小、重量轻、电磁干扰小、元件应力低等优点。

With increased energy demand and environmental concerns, alternate energy sources (fuel cell, wind, photovoltaic and ocean) are becoming popular. The outputs of these energy sources vary widely including some operational limits. Some examples are: (1) Fuel cells generate widely varying low voltage dc (e.g., 22 to 41 V) having slow transient response for load changes and has degraded performance with ripple currents. (2) Permanent magnet synchronous generators used with wind turbines generate varying voltage and varying frequency ac output demanding power factor (pf) corrected ac/dc converters to get a regulated dc bus. For all these sources, an additional dc/ac converter is required for stand alone or utility interface to augment power generation. In addition, when different energy sources are connected to a dc bus, a bidirectional dc-to-dc converter is needed for battery charging as well as to supply the dc bus and an electrolyser used to generate hydrogen for fuel cells requires a dc/dc converter. Therefore, all these energy sources require low cost, highly efficient dc/dc, dc/ac and ac/dc power electronic converters while satisfying the constraints imposed by the energy sources. This is possible using soft-switching (including resonant) converters operating with low losses and high switching frequencies. These converters have a number of advantages, e.g., high efficiency, small size, light weight, reduced EMI, low component stresses, etc.