System and method for regulation of multi-level boost based rectifiers with power factor correction
A control method and system are provided for regulating operation of power factor correction rectifiers based on the non-symmetric boost converter topology. Control of both the front-end stage is enabled taking sinusoidal current from the utility network and a downstream converter providing isolated DC output voltage. Also provided are a method and system for reducing volume of reactive components in boost-based rectifiers with power factor correction. Flux density through the inductor is reduced with a biasing inductor current having a much lower frequency than the switching frequency of the converter.
1. A system for regulating operation of a non-symmetric multi-level boost based front-end stage of a rectifier with power factor correction, the system comprising: a full-wave diode rectifier, the non-symmetric multi-level boost based front-end stage, a charge-balancing isolated downstream DC-DC stage, a controller, and an active capacitive divider coupled to an inductor of the front-end stage at a switching node for reducing a maximum voltage swing value of the inductor, wherein the controller is arranged at an output of the full-wave diode rectifier and an input of the non-symmetric multi-level boost based front-end stage, and the active capacitive divider is dimensioned and controlled ensuring that a maximum value of voltage of the switching node is always higher than an input voltage of the non-symmetric multi-level boost based front-end stage.
2. A system according to claim 1 for reducing a volume and losses of a boost inductor in a PFC rectifier, the system further comprising an auxiliary winding coupled to the inductor and a biasing circuit coupled to the auxiliary winding for providing a low frequency biasing current, thereby cancelling a flux component of the inductor at twice line frequency.
3. The system for regulating operation of a non-symmetric multi-level boost based front-end stage of a rectifier with power factor correction according to claim 1 , wherein the non-symmetric multi-level boost based front-end stage and the controller produce a regulated buss voltage V buss (t) and the active capacitive divider is dimensioned in such a way that the maximum voltage swing value of the inductor is reduced to V buss (t)/3.
4. The system for regulating operation of a non-symmetric multi-level boost based front-end stage of a rectifier with power factor correction according to claim 1 , wherein the controller comprises first and second comparators, first and second windows based Analog-to-Digital converters, a merged multiplier and Digital-to-Analog converter and digital logic, a modes selector, and a current loop compensator.
5. A method for regulating operation of a non-symmetric multi-level boost based front-end stage of a rectifier with power factor correction using the system according to claim 1 or 3 , the method comprising reducing a maximum voltage swing value of the inductor of the front-end stage using the active capacitive divider.
6. A method according to claim 5 for reducing a volume and losses of a boost inductor in a PFC rectifier, the method further comprising providing a biasing circuit and an auxiliary winding for providing a low frequency biasing current, thereby cancelling a flux component of the inductor at twice line frequency.
7. The system for regulating operation of a non-symmetric multi-level boost based front-end stage of a rectifier with power factor correction according to claim 1 or 3 , wherein the charge-balancing isolated downstream DC-DC stage reduces the buss voltage to a lower value compared to a direct output of the non-symmetric multi-level boost based front-end stage.