基于不连续调制的单相LC逆变器控制策略研究

Research on Control Strategy of Single-phase LC Inverter Based on Discontinuous Modulation

为了降低单相逆变器的开关损耗,提高逆变器效率与功率密度,以单相全桥LC型逆变器为研究对象,基于统一调制法提出一种不连续调制策略,在保持两相差模调制信号不变的前提下,通过调整共模调制信号,实现a相桥臂与b相桥臂的开关器件处于交替不动作的状态,从而降低了开关损耗。然后在建立单相全桥LC型逆变器数学模型的基础上,利用幅频特性曲线,对单环路比例-谐振(PR)控制器的参数设计方法展开研究,实现在输入电压扰动与负载电流扰动下,逆变器输出电压对给定电压的精确跟踪。最后进行实验验证,实验结果表明,与传统单极性调制策略相比,所提单相不连续调制策略能够有效降低功率器件的开关损耗,同时所设计的单环路PR控制器能够实现高品质、高精度的电压输出。

In order to reduce the switching loss of the single-phase inverter,improve the efficiency and power density of inverter,a discontinuous modulation strategy based on the unified modulation method is proposed for the singlephase full bridge LC inverter,the differential mode modulation signal between two phase is constant,the common mode modulation signal is adjusted,the switching devices of a-phase and b-phase bridge arm are in inactive state alternating,so the switching loss can be reduced.Then,the mathematical model of the single-phase full bridge LC inverter is established,the parameter design method of the single loop proportional resonant(PR)controller is studied according to the amplitude-frequency characteristic curve,the output voltage can track the given voltage without error under the disturbances of input voltage and load current.Finally,the experiment is carried out,which shows that compared with the traditional single-phase modulation strategy,the switching loss of the power device can be reduced by the proposed single-phase discontinuous modulation strategy,and high quality and precision voltage output can be obtained by the designed single loop PR controller.