并网逆变器输出电流滞环跟踪控制技术研究

Research on Hysteresis-band Current Tracking Control of Grid-connected Inverter

根据并网PWM逆变器运行特点,分析论述了两态滞环调制和三态滞环调制工作原理。研究和设计了一种具有倍频效果的三态滞环控制逆变器并网系统及其状态转移控制逻辑。在并网效率、并网电流脉动和开关频率等方面对两种滞环控制方式进行了对比研究。Pspice仿真和样机实验验证了在输出电流和环宽设定相同的情况下,三态滞环调制较之两态电流滞环调制具有倍频控制的效果,可在相对低的开关频率下获得较快的动态响应,有利于降低功率管开关损耗,提高并网系统运行效率。系统可实现功率因数为1的并网电流输出,且具有稳定性好、电流脉动小等优点。

The principle of two-level hysteresis control and three-level hysteresis control, which are employed in grid-connected PWM inverter, are dissertated in this paper. A grid-connected inverter system with novel three-level hysteresis control, which makes frequency doubling, is researched, and the state-wansition control logic is designed. The comparison of three-level hysteresis control with two-level hysteresis control in the inverter＇s efficiency, the ripple of current, switching frequency is complemented. The results of Pspice simulation and prototype experiment illustrate that three-level hysteresis control has the function of frequency-doubling, at the same conditions of current hysteresis width and output current. So the faster dynamic responsibility in lower switching frequency can be obtained with the three-level hysteresis control, the switching-loss of the power devices can be reduced, which is helpful to improve the efficiency of grid-connected operating. Also, the united power factor of grid-connected current can be obtained; the advantages of good stabilization and small current ripple can be brought.