An Improved Nonlinearities Mitigation Based Control of a Bridgeless Single-Stage AC/DC Converter With Enhanced Reliability

This article presents an improved nonlinearities compensation-based control of a single-stage dual transformer-driven resonant ac/dc topology with enhanced reliability. The designed control law incorporates feedforward and feedback terms, whereas the former is designed using state-plane trajectory (SPT) theory to effectively mitigate the system nonlinearities. Likewise, a simple feedback control term handles slowly varying external perturbations, thus realizing excellent steady-state and transient control performances. The primary-side control ensures ripple-free grid current by achieving fully interleaved operation. Next, the secondary-side features a dual rectifier structure with series resonance for improving the efficiency. Power factor correction (PFC) and output voltage regulation, both are performed via the designed control law which is applied on the secondary control switches. The unique controlled operation of the designed topology results in a uniform voltage/heat stress distribution over all the resonant capacitors, the primary-side switches, and the secondary-side switches, thus greatly enhancing the operational reliability. Extensive experimental investigation via 1 kW prototype design and a TMS320F29377D control board corroborates the theoretical findings under practical operating conditions.