External Ramp Autotuning for Current Mode Control of Switching Converter

摘要

Peak current, valley current or average current mode controlled power converters in either digital or analog implementations obtain a stabilized feedback loop and allow high system bandwidth design by use of an external ramp generator using a slope computation equation or design parameters based on fixing the quality factor of a double pole at one-half of the switching frequency at a desired value The slope of the external ramp waveform is tuned automatically with knowledge of the slope change in the waveform of inductor current of a power converter derived by differentiating a waveform in the current feedback loop. This autotuning of the external ramp generator provides immunity of quality factor change under variations of duty cycle, component values of topological change of the power converter.

主权项

1. An autotuning arrangement for an external ramp generator for stabilizing a current controller for a power converter, said autotuning arrangement comprising:
a circuit to produce a waveform directly corresponding to a slope of a waveform in a current feedback loop of a power converter, a circuit to determine and store a value of said waveform corresponding to said slope of said waveform in said current feedback loop, and means for controlling a slope of an external ramp waveform required to produce a desired quality factor value in a transfer function of said current feedback loop in accordance with said value corresponding to said value of said slope of said waveform in said current feedback loop.