Buck-boost converter with improved efficiency operation

摘要

Systems and methods for providing a buck-boost converter with an improved efficiency are disclosed. The buck-boost converter disclosed operates in 5 different modes, namely in buck mode, half frequency buck mode, half frequency buck-boost mode, half frequency boost mode, and in boost mode. In half frequency buck mode, buck-boost mode, and in half frequency boost mode the switching frequency is halved compared to the switching frequency of buck or boost mode. A simple circuit implementation by adding two offset voltages in ramp signals or PWM comparators enables to halve the switching frequency if required.

主权项

1. A method to achieve a buck-boost converter system having an improved efficiency, comprising the following steps:
(1) providing a buck-boost converter system comprising two PWM comparators, an error amplifier, wherein an output of the error amplifier depends on a difference between a reference voltage and an output voltage of the buck-boost converter, and a control circuit comprising the error amplifier and a logic circuitry controlling an offset voltage circuitry; (2) implementing five different operation modes of the buck-boost converter, wherein each of these five operation modes depends upon a dedicated relation of the input voltage to the output voltage, wherein said five operation modes comprise full frequency buck mode, half frequency buck mode, half-frequency buck-boost mode, half frequency boost mode, and full frequency boost mode; and (3) reducing switching frequency of the buck-boost converter in three operation modes wherein in these three operation modes the input voltage is closer to the output voltage than in the other operation modes using the offset voltage circuitry, wherein the offset voltage circuitry provides positive, zero, or negative offset voltage which is added to the output voltage of the error amplifier, wherein the offset voltage is solely dependent on the operation mode selected.