新能源中压直流汇集系统中的DC/DC变换器需要具备较大容量，而高频DC/DC变换器容量很难做大，因此需要多个模块并联，成本较高。此外，光伏发电的端口电压波动性大，通常需要两级变换器进行级联，导致系统效率降低。为此，该文研究一种适用于新能源中压直流汇集的大容量宽范围输入DC/DC变换器，提出的高中频混频调制方法使得电流波形近似呈断续的梯形波，可显著减小开关器件的电流应力，还使得变压器工作在 500 Hz 的中频，从而更易于设计和制造出较大的容量。此外，变换器的输入电压范围可接近两倍，因此对于大型光伏电站可直接将其连接至光伏阵列，只用一级变换器即可实现最大功率点跟踪(maximum power point tracking，MPPT)和升压功能，系统损耗得到减小。该文分析该变换器的工作原理，讨论参数设计，通过PLECS 仿真软件进行仿真验证，并搭建 300～500 V/±3 000 V、额定功率7。2 kW的原理样机进行实验验证。
A Wide-input Medium Frequency DC/DC Converter Suitable for Medium Voltage DC Collection System for Renewable Energy Sources
The DC/DC converter in the new energy medium voltage DC collection system needs to have a large capacity,while it is difficult to make the capacity of high-frequency DC/DC converter larger,hence it needs multiple modules to be connected in parallel,which consequently leads to higher costs.In addition,the port voltage of photovoltaic power generation has high volatility,which usually requires two levels of converters to be cascaded,resulting in lower system efficiency.For the above reasons,the paper investigates a large-capacity wide-range input DC/DC converter suitable for new energy medium-voltage DC collection.The proposed high and medium-frequency mixing modulation method makes the current waveform approximate to an intermittent trapezoidal waveform,which can significantly reduce the current stress of the switching device,and also enables the transformer work at a medium frequency of 500 Hz,which makes it easier to design and fabricate a larger capacity.In addition,the input voltage range of the converter can be nearly doubled.Therefore,large PV plants can be directly connected to the PV array,using only one converter to realize the MPPT and step-up functions,resulting in a lower system loss.The paper analyzes the working principle of the converter,discusses the parameter design,carries out simulation verification by PLECS simulation software,and builds a 300～500 V/±3 000 V,rated power 7.2 kW principle prototype for experimental verification.
medium voltage DC collectionhigh-power DC/DC converterwide-input voltagehybrid full-bridge three-level convertermedium frequency converter
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维普
