Buck-boost converter circuit, control circuit and associated control method
AssigneeChengdu Monolithic Power Systems Co., Ltd.
InventorChangjiang Chen
Life of this patent
Estimating the term…
Abstract
A buck-boost converter working in a buck mode with buck switching cycles, a boost mode with boost switching cycles or a buck-boost mode with buck-boost switching cycles. Each of the buck-boost switching cycles has an AC phase, an AD phase and a BD Phase, and the duty cycle of the AC phase is determined by a reference signal, a feedback signal and an inductor current sense signal, the duty cycle of the AD phase is controlled and maintained at a preset duty threshold, the time period of the buck-boost switching cycle equals the time period of the buck switching cycle and the time period of the boost switching cycle.
Claims20
A control circuit for regulating a buck-boost converter with an inductor and a switch module having a first power switch, a second power switch, a third power switch and a fourth power switch, wherein the first power switch and the second power switch are coupled in series between an input port and a reference ground with a first common node, the third power switch and the fourth power switch are coupled in series between an output port and the reference ground with a second common node, wherein the inductor is coupled between the first common node and the second common node, the switch module is controlled to on and off to convert an input voltage received at the input port to an output voltage at the output port, the control circuit comprising:
- a buck mode control circuit, configured to control the buck-boost converter to work in a buck-mode by regulating the switch module to operate with buck switching cycles continuously, wherein in each of the buck switching cycles, the first power switch and the second power switch are controlled to conduct on and off switching complementarily, while the third power switch is maintained at the off state and the fourth power switch is maintained at the on state, wherein each of the buck switching cycles comprises an AD phase during which both of the first power switch and the fourth power switch are in the on state and a BD phase during which both of the second power switch and the fourth power switch are in the on state;
- a boost mode control circuit, configured to control the buck-boost converter to work in a boost mode by regulating the switch module to operate with boost switching cycles continuously, wherein in each of the boost switching cycles, the third power switch and the fourth power switch are controlled to conduct on and off switching complementarily, while the first power switch is maintained at the on state and the second power switch is maintained at the off state, wherein each of the boost switching cycles comprises an AC phase during which both of the first power switch and the third power switch are in the on state and the AD phase;
- and
- a buck-boost mode control circuit, configured to control the buck-boost converter to work in a buck-boost mode by regulating the switch module to work with buck-boost switching cycles continuously, wherein each of the buck-boost switching cycles comprises the AC phase, the AD phase and the BD phase, wherein the duty cycle of the AC phase is controlled and determined by a reference signal, a feedback signal indicative of the output voltage, and an inductor current sense signal indicative of a current flowing through the inductor, wherein the duty cycle of the AD phase is controlled and maintained at a preset duty threshold, and the time periods of the buck switching cycle, the boost switching cycle and the buck-boost switching cycle are all equal.
A buck-boost converter, comprising:
- a switch module, comprising a first power switch, a second power switch, a third power switch and a fourth power switch, wherein the first power switch and the second power switch are coupled in series between an input port and a reference ground with a first common node, the third power switch and the fourth power switch are coupled in series between an output port and the reference ground with a second common node, the switch module is controlled to on and off to convert an input voltage received at the input port to an output voltage at the output port;
- an inductor, having a first terminal coupled to the first common node and a second terminal coupled to the second common node;
- a buck mode control circuit, configured to control the buck-boost converter to work in a buck mode by regulating the switch module to operate with buck switching cycles continuously, wherein in each of the buck switching cycles, the first power switch and the second power switch are controlled to conduct on and off switching complementarily, while the third power switch is maintained at the off state and the fourth power switch is maintained at the on state, wherein each of the buck switching cycles comprises an AD phase during which both of the first power switch and the fourth power switch are in the on state and a BD phase during which both of the second power switch and the fourth power switch are in the on state;
- a boost mode control circuit, configured to control the buck-boost converter to work in a boost mode by regulating the switch module to operate with boost switching cycles continuously, wherein in each of the boost switching cycles, the third power switch and the fourth power switch are controlled to conduct on and off switching complementarily, while the first power switch is maintained at the on state and the second power switch is maintained at the off state, wherein each of the boost switching cycles comprises an AC phase during which both of the first power switch and the third power switch are in the on state and the AD phase;
- and
- a buck-boost mode control circuit, configured to control the buck-boost converter to work in a buck-boost mode by regulating the switch module to operate with buck-boost switching cycles continuously, wherein each of the buck-boost switching cycles comprises the AC phase, the AD phase and the BD phase, wherein the duty cycle of the AC phase is controlled and determined by a reference signal, a feedback signal indicative of the output voltage and an inductor current sense signal indicative of a current flowing through the inductor, wherein the duty cycle of the AD phase is controlled and maintained at a preset duty threshold, and the time periods of the buck switching cycle, the boost switching cycle and the buck-boost switching cycle are all equal.
A control method for regulating a buck-boost converter with an inductor and a switch module having a first power switch, a second power switch, a third power switch and a fourth power switch, wherein the first power switch and the second power switch are coupled in series between an input port and a reference ground with a first common node, the third power switch and the fourth power switch are coupled in series between an output port and the reference ground with a second common node, wherein the inductor is coupled between the first common node and the second common node, the switch module is controlled to on and off to convert an input voltage received at the input port to an output voltage at the output port, the control method comprising:
- setting the buck-boost converter to work in a buck mode, a boost mode or a buck-boost mode based on the input voltage and the output voltage;
- when the buck-boost converter is regulated to work in the buck mode, the switch module is regulated to operate with buck switching cycles continuously, wherein in each of the buck switching cycles, the first power switch and the second power switch are controlled to conduct on and off switching complementarily, while the third power switch is maintained at the off state and the fourth power switch is maintained at the on state, wherein each of the buck switching cycles comprise an AD phase during which both of the first power switch and the fourth power switch are in the on state and a BD phase during which both of the second power switch and the fourth power switch are in the on state;
- when the buck-boost converter is regulated to work in the boost mode, the switch module is regulated to operate with boost switching cycles continuously, wherein in each of the boost switching cycles, the third power switch and the fourth power switch are controlled to conduct on and off switching complementarily, while the first power switch is maintained at the on state and the second power switch is maintained at the off state, wherein each of the boost switching cycles comprises an AC phase during which both of the first power switch and the third power switch are in the on state, and the AD phase;
- and
- when the buck-boost converter is regulated to work in the buck-boost mode, the switch module is regulated to operate with buck-boost switching cycles continuously, wherein each of the buck-boost switching cycles comprises the AC phase, the AD phase and the BD phase, wherein the duty cycle of the AC phase is controlled and determined by a reference signal, a feedback signal indicative of the output voltage and an inductor current sense signal indicative of a current passing through the inductor, the duty cycle of the AD phase is controlled and maintained at a preset duty threshold, the time periods of the buck switching cycle, the boost switching cycle and the buck-boost switching cycle are all equal.
Dependencies are inferred from the claim text.