Current sensorless control for single-phase boost-type SMR

In this paper, the single-loop current sensorless controls (SLCSC) for single-phase boost-type switching-mode- rectifiers (SMRs) are developed and digitally implemented in DSP-based system. Compared to the conventional multi-loop control with one inner current loop and one outer voltage loop, there is only one voltage loop in the proposed SLCSCs where its output is used to shift the nominal duty ratio pattern generated from the sensed input and output voltage. Because of no current loop, the efforts of sampling and tracking inductor current are unnecessary. It implies that the proposed SLCSCs are simple and very adaptable to the implementation with mixed-signal integrated circuits. It is also noted that the proposed SLCSCs are operated at continuous-current-mode (CCM). In this paper, first, the effects of shifting nominal duty ratio pattern on the input current waveform are analyzed and modeled with considering the inductor resistance and conduction voltages. It shows that the aligned current waveform can be inherently generated by the nominal duty ratio pattern and the current amplitude is roughly proportional to the shifting phase of nominal duty ratio pattern. Then, a voltage controller is included to regulate the dc output voltage by tuning this controllable phase. Finally, some simulated and experimental results have been given to demonstrate the performances of the proposed SLCSCs.