School of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysia.
Department of Electronic Engineering, Faculty of Engineering, The Islamia University of Bahawalpur, Punjab, Pakistan.
PLoS One. 2020 Feb 6;15(2):e0228636. doi: 10.1371/journal.pone.0228636. eCollection 2020.
For closed-loop controlled DC-AC inverter system, the performance is highly influenced by load variations and online current measurement. Any variation in the load will introduce unwanted periodic error at the inverter output voltage. In addition, when the current sensor is in faulty condition, the current measurement will be imprecise and the designed feedback control law will be ineffective. In this paper, a sensorless continuous sliding mode control (SMC) scheme has been proposed to address these issues. The chattering effect due to the discontinuous switching nature of SMC has been attenuated by designing a novel boundary-based saturation function where the selection of the thickness of boundary is dependent to the PWM signal generation of the inverter. In order to remove the dependency on the current sensor, a particle swarm optimization(PSO) based modified observer is proposed to estimate the inductor current in which the observer gains are optimized using PSO by reducing the estimation errors cost function. The proposed dynamic smooth SMC algorithm has been simulated in MATLAB Simulink environment for 0.2-kVA DC-AC inverter and the results exhibit rapid dynamic response with a steady-state error of 0.4V peak-to-peak voltage under linear and nonlinear load perturbations. The total harmonic distortion (THD) is also reduced to 0.20% and 1.14% for linear and non-linear loads, respectively.
对于闭环控制的 DC-AC 逆变器系统，其性能受到负载变化和在线电流测量的高度影响。负载的任何变化都会在逆变器输出电压中引入不必要的周期性误差。此外，当电流传感器出现故障时，电流测量将不准确，设计的反馈控制律将失效。本文提出了一种无传感器连续滑模控制（SMC）方案来解决这些问题。SMC 的不连续开关特性会产生抖振效应，通过设计一种新的基于边界的饱和函数可以减弱这种效应，其中边界的厚度选择取决于逆变器的 PWM 信号生成。为了去除对电流传感器的依赖，提出了一种基于粒子群优化（PSO）的改进观测器来估计电感电流，其中观测器增益通过使用 PSO 优化来减小估计误差代价函数。在 MATLAB Simulink 环境中对 0.2-kVA DC-AC 逆变器进行了所提出的动态平滑 SMC 算法的仿真，结果表明在线性和非线性负载扰动下具有快速的动态响应，稳态误差为 0.4V 峰峰值。总谐波失真（THD）也分别降低到线性和非线性负载时的 0.20%和 1.14%。
