Circulating current reduction of a grid-connected parallel interleaved converter using energy shaping control

This paper proposes a method to control low frequency circulating currents generated in parallel interleaved converters. In this configuration, inverters are parallelized using magnetically linked inductors. Generally, to improve the harmonic content of the output voltage, carrier interleaving is used. This results in a higher circulating current (differential mode current) to flow through the two Voltage Source Converters (VSCs). High frequency components of circulating currents are efficiently reduced by the mutual inductance of the Coupled Inductors (CI). However, CI cannot efficiently filter the low frequency components. When the uncontrolled circulating currents become too high; they lead to CI saturation, higher switching losses, and degrade the overall performances of the converter. Therefore, this paper presents a global control strategy for a grid-connected parallel interleaved converter based on the concept of Port Controlled Hamiltonian (PCH). With this controller, active and reactive powers delivered to the grid are efficiently controlled. In addition, the controller considerably reduces the value of the low frequency circulating current. Converter performances are evaluated by simulation and compared with the classical PI control and the Linear Quadratic (LQ) control. An experimental setup was developed to verify the feasibility of the proposed system. Results obtained from experiments show a good agreement with the simulation, confirming the performances of the proposed method.