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A new digital control technique for power factor (PF) correction is presented. The main novelty of the method is that there is no current sensor. Instead, the input current is digitally rebuilt, using the estimated input current in the current loop. The circuit measures the input and output voltage by means of low cost ad hoc analog-to-digital converters (ADCs). Taking advantage of the slow dynamic behavior of these voltages, almost completely digital ADCs have been designed, leaving only a comparator and an RC filter in the analog part. Avoiding measuring current can provide a significant advantage compared to analog controllers and this also helps to reduce the total cost. The ultimate objective is to obtain a low-cost digital controller that can be easily integrated as an intellectual property (IP) block into a field-programmable gate array, or an application-specific integrated circuit. The experimental results show a reasonably high PF, despite not measuring the input current, and therefore the feasibility of the method.
Date of Publication: June 2010