Two-phase three-level converter and controller therefor
OwnerTianshu Liu, Yan-Fei Liuinventors
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Abstract
Disclosed are multilevel buck converters, and controllers and methods for operating such converters. Embodiments improve the voltage gain (Vo/Vin) of multi-level DC-DC converters, such as three-level converters, that is imposed by a duty cycle limitation in conventional approaches. According to certain embodiments, the duty cycle of switches is controlled to so that the converter output voltage is increased.
Claims14
A two-phase asymmetrical three-level buck converter, comprising:
- a first input terminal connected to a first common terminal of a first switch connected in parallel with a third switch;
- a first node connected to a second common terminal of the first and third switches, and to a first common terminal of a second switch connected in parallel with a fourth switch;
- a second common terminal of the second and fourth switches connected to a second node and a first terminal of a fifth switch;
- a first capacitor having a first terminal connected to the first node and a second terminal connected to a third node and a first terminal of a sixth switch;
- a first inductor having a first terminal connected to the second node and a second terminal connected to a main output terminal;
- a second inductor having a first terminal connected to the third node and a second terminal connected to the main output terminal;
- a common node connected to a second input terminal, a second terminal of the sixth switch, a second terminal of the fifth switch, and a second output terminal;
- and
- a second capacitor connected between the main output terminal and the second output terminal.
A controller for a series capacitor buck converter comprising first and second control switches and first and second synchronous rectifier (SR) switches, the controller comprising:
- an input that receives a signal corresponding to the converter output voltage or current;
- a circuit that generates a duty cycle signal based on the sensed output voltage or current;
- a driving circuit that generates gate drive signals for switches of the converter;
- wherein the controller drives the switches so that:
- the first and second control switches are turned on and off once, sequentially, during one switching cycle, wherein a duty cycle of each of the first and second control switches is greater than 50% such that the on times of the first and second control switches overlap by a selected interval;
- and
- the first and second SR switches are each turned on and off once, sequentially, during a switching cycle, wherein each of the on times of the first and second SR switches coincides with an off time of one of the first and second control switches;
- wherein the first and second SR switches are off during the overlaps of the on times of the first and second control switches.
A method for controlling a series capacitor buck converter comprising first and second control switches and first and second synchronous rectifier (SR) switches, comprising controlling the switches so that:
- the first and second control switches are turned on and off once, sequentially, during one switching cycle, wherein a duty cycle of each of the first and second control switches is greater than 50% such that the on times of the first and second control switches overlap by a selected interval;
- and
- the first and second SR switches are each turned on and off once, sequentially, during a switching cycle, wherein each of the on times of the first and second SR switches coincides with an off time of one of the first and second control switches;
- wherein the first and second SR switches are off during the overlaps of the on times of the first and second control switches.
Dependencies are inferred from the claim text.