Auxiliary ramps for saturation prevention in symmetric current-programmed DC/DC converters

The use of an auxiliary ramp for stabilizing a current-programmed, symmetric, DC/DC converter is examined for the case where each switching device has a different, adjustable ramp. It is shown that the ramp slope may be varied so that not only is the current-programmed loop stable but also that the DC component of the magnetising current arising from mismatched transistor storage times or mismatched transistor or diode on-state voltage drops can be zeroed. In the context of current-programming, proportional base drive schemes are shown to have a stabilizing effect compared to the destabilizing effect of constant base drives.