Decoupled $dq$ Current Control of Grid-Tied Packed E-Cell Inverters in Vehicle-to-Grid Technologies

This article investigates a decoupled vector current control strategy for grid-tied single-phase nine-level Packed E-Cell (PEC) inverters for vehicle-to-grid (V2G) technologies. The control design is based on a loop shaping approach, where performance specifications such as desired closed-loop bandwidth, closed-loop stability, robustness to pure time-delays in control loops/process, and decoupling between direct (<inline-formula><tex-math notation="LaTeX">$d$</tex-math></inline-formula>) and quadrature (<inline-formula><tex-math notation="LaTeX">$q$</tex-math></inline-formula>) axis of control signals are specified in the frequency domain. The control design problem is formulated as a convex optimization problem whose solution results in a multivariable controller in the <inline-formula><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> framework. The effectiveness of the proposed control strategy in terms of robust stability, current tracking, and improved total harmonic distortion is evaluated by experimental and simulation results under several case studies. The results also show that the designed controller provides the desired transient response as well as decoupling between the <inline-formula><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> output currents.