Patent ID: 8610419
Filing Date: 2013-12-17
Classification: H02M

Abstract:
1. A control method for a buck-boost power converter which includes an inductor, a first switch coupled between a power input terminal of the power converter and a first terminal of the inductor, a second switch coupled between the first terminal of the inductor and a ground terminal, a third switch coupled between a second terminal of the inductor and the ground terminal, and a diode having an anode coupled to the second terminal of the inductor and a cathode coupled to a power output terminal of the power converter, the control method comprising: monitoring an input voltage at the power input terminal, an output voltage at the power output terminal, and a load current at the power output terminal, for determining a voltage ratio between the two terminals of the inductor; selecting one from a buck mode, a first buck-boost mode, a second buck-boost mode, and a boost mode according to the voltage ratio for the power converter; amplifying a difference between a first signal and a reference voltage for generating a second signal, wherein the first signal is a function of the output voltage; providing a first clock and a second clock; generating a third signal and a fourth signal according to the first clock and the selected mode; comparing the second signal with the third signal for generating a fifth signal; comparing the second signal with the fourth signal for generating a sixth signal; switching the first to third switches according to the selected mode, the fifth and sixth signals, and the first and second clocks; and in the first and second buck-boost modes, switching the first to third switches in a sequence including: turning off the first switch, turning on the second switch, and turning off the third switch; turning on the first switch, turning off the second switch, and keeping the third switch off; and keeping the first switch on, keeping the second switch off, and turning on the third switch.