Input current shaping has been required in AC-DC rectifiers in order to comply with regulations that specify limits on input current harmonics. Boost power factor correction (PFC) rectifiers are widely used to achieve near-unity input power factor and low current harmonic distortion. This thesis addresses digital control techniques aimed at improving efficiency and reducing harmonic distortion in digitally controlled single-phase boost PFC rectifiers operating over wide range of loads. By taking advantage of the flexibility of digital controllers and using a discontinuous conduction mode (DCM) detection circuit, several proposed control techniques achieve low current harmonic distortion and improve system efficiency over wide load range in DCM and in continuous conduction mode (CCM). In heavy load operation, a simple passive power sharing technique is introduced for interleaved boost PFC rectifiers to increase system power modularity; in medium to light load operation, proposed adaptive approaches improve light load efficiency by extending switching period to achieve low voltage switching and by adjusting switching frequency to scale with processed power. Furthermore, a new current error estimation approach is applied to relieve current sensing limitations and to reduce current controller design effort. Digital control techniques are implemented and verified using field programmable gate array (FPGA) in several boost PFC rectifier prototypes.
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