一种光伏发电软开关直流升压电路-电测与仪表.doc

一种光伏发电软开关直流升压电路* 余运俊 摘要：针对传统boost电路升压比不高的缺陷，改进了一种组合式光伏发电直流升压电路，该电路结构前端采用boost电路和半桥电路串联组合成的升压逆变电路，用隔离变压器实现两级升压，副边采用副边移相控制的一种改进的三电平结构。改进后电路的开关管数量增加，电路中的开关管均实现软开关，从而减少开关过程中的损耗，电路的效率提高。该电路的特点：1）电路结构简单明了；2）平均电压增益较高，为后端的逆变提供一个较高的电压；3）所有开关管实现软开关功能，效率提高。 关键词：光伏发电；副边移相控制；软开关；直流升压 中图分类号TM910　文献标志码：1001-1390（201）00-0000-00 A photovoltaic power soft switching DC/DC circuit Yu Yunjun, Wang Shuocheng, Xue Yuntao, Huo Jiahe, Wang Huan (College of Information Engineering, Nanchang University, Nanchang 330031, China) Abstract: A combined photovoltaic DC-DC boost circuit is improved according to the step-up ratio of traditional boost circuit is not high. Boost circuit and half-bridge circuit are adopted in series combination to achieve boost inverter circuit in front-end of circuit structure. Isolation transformer can realize two step voltage transformations. An improved three-level configuration is adopted in the secondary side of secondary side phase-shift control. The numbers of IGBT are increased with an improved circuit. All of the IGBT in circuit achieved soft switching and reduced loss during switch process. In addition, the efficiency of circuit is improved. This circuit has the following characteristics: 1.The structure of circuit is simple and clear; 2. The gain range of average voltage is higher and provides a high voltage for back-end of inverter; 3.The soft switch can be achieved in all IGBT to enhance efficiency. Keywords: photovoltaic power, secondary side phase shift, soft switch, DC-DC boost circuit 0 引言 传统boost电路有结构简单的优点[1]，但若要实现较高的升压比，则开关损耗同时增加，影响效率，实际的开关占空比不能太大，因为占空比一旦过大将失去升压作用，较大占空比会导致开关管的温升，增加损耗。由于实际开关管的占空比不能过大，则电压增益不高[2-4]，升压后的电压不能很好的为后续逆变作准备[5-6]，在这种情况下提高升压比是要以增加大量损耗为代价的。同时，若要修改电路结构，在增加开关管和LC电路数量的同时，高频阶段下的电路损耗也将明显增加[7-8]。为了提高电压增益[9]，通常采取直—交—直的升压方式，即总体为直流升压[10]。用变压器隔离原副边。所得电压能较好的为后续逆变作准备，并入电网[11]。原边逆变电路采用半桥逆变[12]，结构简单。副边整流电路采用副边移相控制[13-14]策略可保证所有功率器件工作在0.5的占空比，能够优化功率器件的开关环境[15]。电路由谐振电感配合原边变压器漏感与原边寄生电容产生谐振作用，使原边开关管实现ZVS、ZCS，副边的移相控制使副边开关管实现ZVS、ZCS[16-17]。 根