An abc Reference Frame Hysteresis Current Controller for Grid Connected Converter With Constant Switching Frequency Operation

For a grid-connected inverter, a constant switching frequency hysteresis current control (HCC) technique based on targeted trajectory of current space vector (HCC-TTCSV) is proposed. The harmonic spectrum of inverter line-to-line voltage, produced by the proposed HCC-TTCSV, is ensured to exhibit similar characteristics to that of voltage-controlled conventional seven-segment space vector modulation (SVM) technique. The proposed current controller is a novel one (i.e., first of its kind) that allows the phase currents to be checked with online calculated current boundaries in stationary abc reference frame. Instead of following a current error boundary, phase current boundary check is performed. The phase current boundary values during every seven-segment switching cycle, however, are found out by observing the projections of vertices of targeted trajectory of current vector along abc axes using few trigonometric relations. The proposed controller is designed for three-phase two-level voltage-source inverter (2L-VSI), and it works well for both L filter and LCL filter. Compensation methods to overcome the current distraction effect caused by factors such as finite rate of current sampling, dead time, gate driver circuit's propagation time, and other nonidealities of the system are also discussed in detail. Theoretical background is established, and experimental verification is presented for validation.