Passivity-Based Robust Controller Design for Load-Independent Voltage Source Inverters

We propose a novel voltage controller design procedure for voltage source inverters (VSIs) with uncertain loads, focusing on the passivity of loads. VSIs have been widely used in many applications. A VSI must regulate the load voltage to its sinusoidal reference quickly and accurately without distortion. It is essential to design a voltage controller that takes into account various load conditions since it is rarely known in advance what types of loads are connected to the VSI. In particular, it is challenging to suppress the voltage harmonic distortion caused by a nonlinear load, such as a diode rectifier, while achieving fast-tracking and zero steady-state error. A controller designed by the proposed procedure guarantees robust stability of the VSI independent of the load type and value. Namely, no information about uncertainties of load is needed to stabilize the VSI. Moreover, the proposed procedure realizes zero-steady state error, fast-tracking, and low distortion. We demonstrate the effectiveness of the proposed controller through comparative analysis with the proportional resonant (PR) and conventional robust controllers via simulations and experiments.