TESIS DOCTORAL DEPARTAMENTO DE INGENIERÍA ELECTRÓNICA UNIVERSIDAD POLITÉCNICA DE VALENCIA AUTOR: MARCOS PASCUAL MOLTÓ. DIRECTOR: GABRIEL GARCERÁ SANFELIU.OCTUBRE 2007.
Parallel converter systems are an interesting solution to the problem of providing a tightly regulated output voltage at high current levels. Paralleling of converters allows for equal sharing of the load current betweenmodules. In this way, the stress in the semiconductor switches is reduced and reliability is improved.
In multimodule parallel converter systems, a current mode control scheme, like average current mode control (ACC), is usually needed in order to share the current between modules. In this scheme the control loop dynamic characteristicsdepend strongly on the line and load conditions, and also on the number of modules on stream.
In this thesis two different robust model-following (RMF) control techniques have been applied to parallel converter systems in order to improve the robustness of the ACC control. This work has been carried out in three different steps:
In first place, a high-pass RMF control scheme has been presented and applied to the voltage loop of a parallel Buck DC-DC converter. The proposed scheme adds a inner loop to the conventional current and voltage ACC loops, reducing the sensitivityof the outer voltage loop to the changing power stage parameters: number of modules, input voltage, load and component tolerances. Also, the loop improves significantly the disturbance rejection of the converter, i.e. the closed loop output impedance and audiosusceptibility, at low frequencies in comparison with conventional ACC.
In multimodule parallel converter systems, a current mode control scheme, like average current mode control (ACC), is usually needed in order to share the current between modules. In this scheme the control loop dynamic characteristicsdepend strongly on the line and load conditions, and also on the number of modules on stream.
In this thesis two different robust model-following (RMF) control techniques have been applied to parallel converter systems in order to improve the robustness of the ACC control. This work has been carried out in three different steps:
In first place, a high-pass RMF control scheme has been presented and applied to the voltage loop of a parallel Buck DC-DC converter. The proposed scheme adds a inner loop to the conventional current and voltage ACC loops, reducing the sensitivityof the outer voltage loop to the changing power stage parameters: number of modules, input voltage, load and component tolerances. Also, the loop improves significantly the disturbance rejection of the converter, i.e. the closed loop output impedance and audiosusceptibility, at low frequencies in comparison with conventional ACC.
