Buck-boost power converter and associated mode transition control module

Patent metadata

Field	Value
Publication number	US-2016190931-A1
Application number	US-201514757869-A
Country	US
Kind code	A1
Filing date	Dec 23, 2015
Priority date	Dec 24, 2014
Publication date	Jun 30, 2016
Grant date	—

Abstract

A buck-boost power converter and a mode transition control module. The mode transition control module includes a buck duty cycle sensing and comparison circuit and a boost duty cycle sensing and comparison circuit. The buck duty cycle sensing and comparison circuit can provide a first mode transition control signal through comparing a first signal indicative of a buck duty cycle with a first threshold signal indicative of a buck duty threshold to regulate the buck-boost power converter to transit between a buck mode and a buck-boost mode. The boost duty cycle sensing and comparison circuit can provide a second mode transition control signal through comparing a second signal indicative of a boost duty cycle with a second threshold signal indicative of a boost duty threshold to regulate the buck-boost power converter to transit between a the buck-boost mode and a boost mode.

First claim

What is claimed is:

1 . A mode transition control module for regulating a buck-boost power converter to transit between a buck mode and a buck-boost mode and between the buck-boost mode and a boost mode, the mode transition control module comprising:
a buck duty cycle sensing and comparison circuit configured to receive a first signal indicative of a buck duty cycle of the buck-boost power converter, and to compare the first signal with a first threshold signal indicative of a buck duty threshold to provide a first mode transition control signal; wherein the buck duty threshold has a first hysteresis; and wherein when the buck duty cycle is larger than the buck duty threshold, the first mode transition control signal is configured to regulate the buck-boost power converter to transit from the buck mode to the buck-boost mode and meanwhile to regulate the buck duty threshold to decrease to a second buck duty threshold with a decrement equals to the first hysteresis; and wherein when the buck duty cycle is smaller than the second buck duty threshold, the first mode transition control signal is configured to regulate the buck-boost power converter to transit from the buck-boost mode to the buck mode and meanwhile to regulate the buck duty threshold to restore from the second buck duty threshold to the buck duty threshold; and a boost duty cycle sensing and comparison circuit configured to receive a second signal indicative of a boost duty cycle of the buck-boost power converter, and compare the second signal with a second threshold signal indicative of a boost duty threshold to provide a second mode transition control signal; wherein the boost duty threshold has a second hysteresis; and wherein when the boost duty cycle is larger than the boost duty threshold, the second mode transition control signal is configured to regulate the buck-boost power converter to transit from the buck-boost mode to the boost mode, and meanwhile to regulate the boost duty threshold to decrease to a second boost duty threshold with a decrement equals to the second hysteresis; and wherein the second mode transition control signal is further configured to regulate the buck-boost power converter to transit from the boost mode to the buck-boost mode when the boost duty cycle is smaller than the second boost duty threshold, and meanwhile to regulate the boost duty threshold to restore from the second boost duty threshold to the boost duty threshold.

2 . The mode transition control module of claim 1 , wherein the first signal comprises a first control signal or a second control signal, and wherein the first control signal and the second control signal are respectively configured to control a first power switch and a second power switch coupled in series between an input port and a reference ground of the buck-boost power converter; and wherein the first threshold signal comprises a first reference pulse signal having a pulse width indicative of the buck duty threshold; and wherein the buck duty cycle sensing and comparison circuit is configured to compare the a pulse width of the first control signal with the pulse width of the first reference pulse signal to generate the first mode transition control signal.

3 . The mode transition control module of claim 2 , wherein the buck duty cycle sensing and comparison circuit comprises:
a first reference signal generation circuit configured to receive the first mode transition control signal at a control input terminal and to provide the first reference pulse signal at an output terminal, and further configured to regulate the pulse width of the first reference pulse signal based on the first mode transition control signal so that a ratio of the pulse width of the first reference pulse signal to a period of the first reference pulse signal equals to the second buck duty threshold when the buck duty cycle is larger than the buck duty threshold and equals to the buck duty threshold when the buck duty cycle is smaller than the second buck duty threshold; and a first D flip-flop having a first data input terminal, a first clock input terminal and a first non-inverse output terminal, wherein the first data input terminal is configured to receive the first control signal and the first clock input terminal is configured to receive the first reference pulse signal, and wherein the first D flip-flop is configured to transmit the first control signal received at the first data input terminal to the first non-inverse output terminal at each falling edge of the first reference pulse signal and hold and provide the transmitted first control signal as the first transition control signal at the first non-inverse output terminal until the next falling edge of the first reference pulse signal comes; and wherein each of the first control signal, the first reference pulse signal and the first mode transition control signal has a first logic state and a second logic state; and wherein the first mode transition control signal changing from the second logic state to the first logic state indicates that the buck duty cycle is larger than the buck duty threshold; and wherein the first mode transition control signal changing from the first logic state to the second logic state indicates that the buck duty cycle is smaller than the second buck duty threshold.

4 . The mode transition control module of claim 2 , wherein the buck duty cycle sensing and comparison circuit comprises:
a first reference signal generation circuit configured to receive the first mode transition control signal at a control input terminal and to provide the first reference pulse signal at an output terminal, and further configured to regulate the pulse width of the first reference pulse signal based on the first mode transition control signal so that a ratio of the pulse width of the first reference pulse signal to a period of the first reference pulse signal equals to the second buck duty threshold when the buck duty cycle is larger than the buck duty threshold and equals to the buck duty threshold when the buck duty cycle is smaller than the second buck duty threshold; and a first D flip-flop having a first data input terminal, a first clock input terminal and a first non-inverse output terminal, wherein the first data input terminal is configured to receive the second control signal and the first clock input terminal is configured to receive the first reference pulse signal, and wherein the first D flip-flop is configured to transmit the second control signal received at the first data input terminal to the first non-inverse output terminal at each falling edge of the first reference pulse signal and hold and provide the transmitted second control signal as the first transition control signal at the first non-inverse output terminal until the next falling edge of the first reference pulse signal comes; and wherein each of the second control signal, the first reference pulse signal and the first mode transition control signal has a first logic state and a second logic state; and wherein the first mode transition control signal changing from the first logic state to the second logic state indicates that the buck duty cycle is larger than the buck duty threshold; and wherein the first mode transition control signal changing from the second logic state to the first logic state indicates that the buck duty cycle is smaller than the second buck duty threshold.

5 . The mode transition control module of claim 2 , wherein the buck duty cycle sensing and comparison circuit comprises:
a first reference signal generation circuit configured to receive the first mode transition control signal at a control input terminal and to provide the first reference pulse signal at an output terminal, and further configured to regulate the pulse width of the first reference pulse signal

Assignees

• Chengdu Monolithic Power Sys

Inventors

• Zhang Jian

Classifications

• H02M3/1582 Primary

  Buck-boost converters (H02M3/1584 takes precedence) · CPC title

• H02M2001/0009

  Electricity · mapped topic

• H02M1/0009

  Devices or circuits for detecting current in a converter · CPC title