Single ADC Digital PFC Controller Using Precalculated Duty Cycles

Abstract

Abstract-Traditional digital PFC (Power Factor Correction) uses three sensors to measure the input and output voltages and the input current. Each sensor, especially the input current one, increases the cost of the system and generates power losses in case of resistive sensors. This paper presents a controller for boost PFC converters. It uses pre-calculated duty cycles generated offline, and applies them to the switch. In order to control the converter with non-nominal conditions, just one ADC (Analog to Digital Converter) is used, which measures the output voltage. Measuring the average and the ripple of the output voltage with this ADC, the controller takes compensation action for changes in the input voltage but also in the load of the converter. The average value is used to control the input voltage changes, whilst the ripple value is used to control load changes. These two loops present low frequency bandwidth, so the ADC and the whole system can be low cost. Finally, a comparator is used to detect the zero-crossing of the input voltage, so the pre-calculated values are synchronized with the ac mains. In this way, the converter only uses one ADC and one comparator, both with low bandwidth. Results show that high power factor and normative compliance are reached, even under non-nominal conditions.

Boost PFC Sem Sensor De Corrente Utilizando Técnica De Deslocamento De Amostra De Tensão

“…Fica, portanto, demonstrado que a operação com elevado fator de potência será garantida pelo simples deslocamento da forma de onda da tensão de entrada, considerando as condições definidas em (10) e (11).…”

Line Current Distortion Compensation for DCM/CRM Boost PFC Converters

“…Therefore, M1 and M2 can be treated as constant values and denoted in (1), where VCin(k) represents that the values of VCin during k th switching period. Eventually, the average inductor current for the k th triangle over a switching cycle, <iL>Ts(k), can be derived as (2), where fs=1/Ts is the switching frequency. Because the switching period is much smaller than the AC line period, the total filtered inductor current, If, or the absolute value of input current, |Iin| can be derived as (3) over a half period of the AC mains with the notation k eliminated.…”

Power Quality Enhancement in Residential Smart Grids Through Power Factor Correction Stages

“…A current sensorless technique with an artificial input voltage, stored in a Look-Up Table (LUT) to gain immunity under distorted input voltage, is presented in [31]. A more sophisticated technique, which precalculates the duty-cycle sequence, extending the load range of application with no input voltage or current acquisition, assuming that the reference is sinusoidal is presented in [32]. In [33], [34], a current sensorless technique is extended for multiphase current interleaved topologies.…”