Design and Discretization of Multi-Resonant Current Controllers

Multi-Resonant controllers are suitable for tracking periodic non-sinusoidal reference currents, used in variety of applications such as active filters, disturbance-observer (DOB) based control, etc. The discretization of the multi-resonant controllers causes a significant error both in the resonant frequency and in the phase due to the narrow band and nearly infinite gain of these multi-resonant controllers. Therefore, zero steady-state tracking error is not assured, and stability may be compromised. This paper proposes the most accurate discretization method for any multi-resonant controller with damping term. Processor-in-the-loop (PIL) real-time simulation results have been conducted, demonstrating the validity of the proposed discrete-time implementation.