光储充一体机的核心部分——双向DC/DC很难同时做到隔离和宽电压范围输出。提出一种两相并联的不对称CLLC电路拓扑及相关控制策略,采用交错并联和拓扑复用的控制方式,使变换器产生半桥、全桥、全桥交错并联3种模式,提供宽电压增益范围,使变换器工作于过谐振频率点附近,3种工作模式均实现了原边侧开关管的零电压开通。针对全桥交错并联模式下因实际谐振参数差异导致的输出功率不均衡问题,提出在增益较小相进行补偿的方法——增加副边开关管的移相控制方法。通过理论分析,对相应的增益公式进行推导,验证了该方法能够调整输出增益,进而均衡功率。最终,在构建的3.3 kW实验平台上进行验证,该变换器可提供满足储能电池多段式充电所需的电压和功率范围,在3种模式下均保持软开关,并实现全桥交错并联模式下的功率均衡。
Abstract
The traditional photovoltaic storage charger widely used in the photovoltaic storage DC microgrid, the core part-bidirectional DC/DC is difficult to do at the same time to isolate and storage batteries need a wide range of voltage output. In this paper, a two-phase parallel asymmetric CLLC circuit topology and the associated control strategy are proposed, which adopts the control method of interleaved parallel and topology multiplexing to generate three modes of half-bridge, full-bridge, and full-bridge interleaved parallel to provide a wide voltage gain range, so that the converter operates near the above-resonant frequency point, and the three modes of operation achieve the zero-voltage turn-on of the primary-side switching tube. Aiming at the output power imbalance problem caused by the difference of actual resonance parameters in the full-bridge interleaved parallel mode, a method of compensating for the smaller gain phases, the phase-shift control method of increasing the secondary-side switching tubes is proposed. Through theoretical analysis and derivation of the corresponding gain formula, it is verified that the method can adjust the output gain and thus equalize the power. Finally, it is verified on the constructed 3.3 kW experimental platform that the converter can provide the voltage and power ranges required to satisfy the multi-stage charging of energy storage batteries, maintains the soft-switching in all the three modes, and achieves the power equalization in the full-bridge interleaved parallel mode.
关键词
双向DC/DC /
不对称CLLC /
交错并联 /
功率均衡
Key words
bidirectional DC/DC /
asymmetric CLLC /
interleaved parallel /
power equalization
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