Research On Dual-loop Digital Control Technique Based On Beat Control For Inverters

With the development of power electronics and increased requirements of electrical equipment for power performance, all kinds of inverter waveform control technology developed, while facing new challenges. Beat control that has been mainly used for machine control, etc, due to good tracking performance, has not yet been applied at the inverter's sinusoidal output waveform control. This paper focuses on dual-loop digital control technique with the inductor current feedback and beat voltage controller for single-phase inverter. The improvement of control scheme, the derivation of theoretical issues and specific design process are given a detailed analysis and description.Firstly, this paper has presented a single full-bridge PWM inverter model, introduced briefly beat digital control system design and chosen the beat ripple-free method to design voltage controller according to the specific parameters of the inverter. The simulation results of beat control in a single voltage loop demonstrated its advantages in the static characteristics and shortcomings with dynamic and non-linear load. After pointing out the main reason for poor performance of single-loop design, we used double-loop control to improve, and then discussed how to solve the design complexity and the influence between the inner and outer loop in the double loop system.Based on theoretical analysis and calculations, a single-phase inverter prototype applying beat double-loop control technique is researched in the paper, the experimental results accord with theoretical analysis. At last the problems of the experiment are proposed to be further studied.