Patent ID: 8319483

Claim:
A method for switching between buck, boost, and alternating buck-boost modes of operation of a cascaded buck-boost converter, the converter comprising an inductor, the method comprising: if the converter is in boost mode and the duty cycle drops below a predetermined value for at least a first predetermined number of cycles, transferring the converter to alternating buck-boost mode; if the converter is in buck mode and the duty cycle climbs above a second predetermined value for at least a second predetermined number of cycles, transferring the converter to alternating buck-boost mode; if the converter is in alternating buck-boost mode, and the duty cycle climbs above a third predetermined value for at least a third predetermined number of cycles, transferring the converter to boost mode, while if the duty cycle drops below a fourth predetermined value for at least a fourth predetermined number of cycles, transferring the converter to buck mode; when the converter operates in a buck mode, controlling the input current according to a pre-programmed buck mode input current control; when the converter operates in a boost mode, controlling the input current according to a pre-programmed boost mode input current control; and, when the converter operates in an alternating buck-boost mode, controlling the input current according to a pre-programmed buck-boost mode input current control.