Research On The Dual-Buck Inverter

Digital control is one of the most important direction of power electronics. Compared with analogical control, digital control has a lot of advantages, For example, it eliminates common problems in analogicial devices such as parameter diversity, temperature drift and etc. Digital control is commonly achieved by software, which is easy to be transplanted or second empolded.Meanwhile, it is also very easy to adopt some advanced control arithmetic in digital system in addition to traditional digital PID control, such as some nonlinear control arithmetic, and then the entire performance of digital system can be improved greatly.The dual buck inverter (DBI), which is a simple and reliable inverter topology, is choosed as the research object in this paper. The principle of the two level hysteresis current control dual buck inverter is analysed. The dynamic and ouput performance of the inverter system is also analysed by simulation with Saber software, and the main reasons is enduced. As the calculate speed of the DSP core is consided, digitally and analogically hybrid control scheme is adopted in this paper. Digital PI control is adopted in voltage loop, which has good stable performance; analogical hysteresis current control is adopted in current loop, which has good dynamic performance. A 2kVA experiment protopype is designed and the experiment has been carried out. Experimental results verifies that the digital control scheme obtain the same performance as the analogical double closed-loop control. Due to the flexible characteristic of digital control, the output frequency of this system can change along the range of 360~800Hz and good performance are always gotten.The integrate megnatics on the two independent output filter inductors in dual buck inverter is researched in this paper. The result of the direct coupling can't make the non biased half cycle mode (NBHCM) come true is concluded, but the non biased half cycle mode is realized by indirect coupling. So the magnetic device volume and weight in the output filter is reduced, and the efficiency of the system has been improved.