Current-sensorless control of an SPWM H-Bridge-based PFC rectifier designed considering voltage sag condition

• The sensorless techniques in rectifiers are introduced as an attractive option to meet the PFC requirements such as: DC voltage regulation under AC voltage sags at input, load step changes at output, unitary power factor and constant low THD current input.
• The mathematical model and control rule for current sensorless single-phase power factor correction rectifiers are introduced and analyzed.
• The proposed control strategy improves the overall performance of PFC rectifiers when compared with similar systems presented in the open literature while reducing the computational-burden associated with the digital controller of the PFC.
• The proposal is based on SPWM, does not require a variable transformation into the dq0 reference frame nor the need of complex compensators after the PI controller stage.

This paper presents and details the H-Bridge PFC rectifier control scheme. This control is a step forward in sensorless current control schemes for performance improvements of single-phase bidirectional rectifiers. The H-Bridge PFC rectifier is designed based on a single PI controller loop fed by DC reference signals. Regarding dynamic operating conditions, the proposed control can maintain a regulated DC voltage under varying conditions at input (voltage sags) and output (load step changes) ports while maintaining an unitary power factor (PF) and constant THD current input at any of these conditions. Different to other investigations, this control proposal uses SPWM, does not require a variable transformation into the dq0 reference frame, and the complex compensators accompanying to the PI controller stage are no longer needed. Therefore, this proposal is aimed to reduce the complexity of the control scheme and to improve the overall dynamic response of the PFC rectifier. The experimental results obtained from the scaled-down prototype setup, which was built for research purposes, validate the control law, mathematical model and quantitative comparison between simulation and experiment, both considering the parasitic resistances of the inductor and semiconductor switches.

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