Novel Single-Loop dq Control for <i>LC</i> Filter-Based Single-Phase Standalone Inverter Systems Under Nonlinear Loads

Standalone inverters must maintain their output voltage sinusoidal to ensure efficacious operation of the connected loads. The voltage profile is affected by the filters, modulation technique, and control strategy. The filters are limited by switching frequency under linear loads and are ineffective under nonlinear loads. These limitations provide an opportunity to achieve the objectives using newer control schemes. Single-loop controls are simpler to implement and are faster in response compared to conventional cascaded controllers. This article focuses on developing and studying a novel linear control theory-based single-loop direct and quadrature (dq) control that has minimum execution time, fixed switching frequency, and a simple implementation algorithm for standalone inverter systems. This controller is tested under different loading and operating conditions. Furthermore, the proposed controller is extended to mitigate lower order harmonics under nonlinear load applications. The effectiveness of the control is tested experimentally against conventional controllers.