Predictive-Based Delay Compensation for Classical VOC Control with Enhanced Transient Performance in Grid-Connected Inverters

Time delay, mainly caused by analog-to-digital conversion (ADC), calculation time, and pulse width modulation (PWM), is inevitably introduced in a digitally controlled grid-connected inverter. The time delay will reduce the phase margin of the control system, which, in turn, limits the closed-loop bandwidth and affects the response speed, increasing the steady-state error of the system. This paper proposes two predictive-based methods for time delay compensation. Both methods are used to improve the performance of the grid-connected converter in classical voltage-oriented control (VOC). By compensating for the time delay, the control bandwidth of the system is increased. The proportional-integral (PI) controller can be configured with a higher gain while ensuring an adequate phase margin, achieving a faster dynamic response. Lastly, we verify the effectiveness of these two methods through simulation results and provide a detailed comparison between them in terms of steady-state and transient performance with/without considering parameter variations.