A Novel Current Controller for Grid-Connected Voltage-Source-Inverters

In this article, a new open-loop current controller based on model prediction method for grid-connected voltage-source-inverters (VSIs) is proposed, which consists of two proportional factors and a delay part (Proportional-Proportional-Delay, PPD). First, the working principle of the PPD controller is explained from the combined step response perspective based on a L-R load, and parameter constraints of PPD controller are derived and discussed from the time domain and differential-integral transform perspectives, respectively. After that, parameter design rules of PPD controller are given by considering the constraint of switching frequency. Due to the sensitivity of the model prediction method to nonideal factors, such as voltage drops of semiconductor devices, sampling, and driving delays, etc., influences of these nonideal factors on performance of PPD controller are discussed in this article, and corresponding compensation strategies are given as well. Finally, the effectiveness of proposed PPD controller and its compensation strategy against nonideal factors are verified by experimental results from a 3 kW prototype in laboratory.