Modulation mode for a switching power converter

A method of operating a switching power converter, wherein the power converter comprises an inductor and a plurality of switches that are switchable to couple the inductor to terminals of the power converter, the method comprising:

• operating the power converter in a modulation mode in which a current through the inductor is modulated by operating the power converter in a repeating sequence of predetermined switching states of the plurality of switches;
• controlling a current waveform of the current through the inductor in the modulation mode by controlling a transition between the switching states of the repeating sequence, wherein the current waveform is controlled to include within one period of the current waveform:
• a first section of rising current corresponding to a first switching state,
• a second section corresponding to a second switching state, wherein the second section of the current waveform does not reach or cross a zero value of the current, and
• a third section of falling current corresponding to a third switching state,
• wherein the first section of the current waveform follows in direct succession to the third section of the preceding period of the current waveform, and
• wherein the control of the current waveform allows a length of a period of the current waveform to change,
• wherein in the modulation mode, a transition from the first section to the second section of the current waveform is controlled by transitioning the operation of the power converter from the first switching state to the second switching state upon the inductor current reaching a first threshold and wherein a transition from the second section to the third section of the current waveform is controlled by transitioning the operation of the power converter from the second switching state to the third switching state upon the inductor current reaching a second threshold,
• wherein one of the first and second thresholds is derived from a comparison of a current reference for an output current of the power converter and a monitored output current of the power converter, and wherein the other of the first and second thresholds is determined from the derived threshold and a desired duration of the second section.