Multi-level power converter with light load flying capacitor voltage regulation

Patent metadata

Field	Value
Publication number	US-11539294-B2
Application number	US-201816050746-A
Country	US
Kind code	B2
Filing date	Jul 31, 2018
Priority date	Jul 31, 2018
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

A multi-level power converter and a method using first, second, third and fourth switching elements, an inductor, and a flying capacitor are presented. A first terminal of the inductor may be connected to a switching terminal connecting the second and third switching elements. A first terminal of the flying capacitor may be connected to a terminal connecting the first and second elements. A second terminal of the flying capacitor may be connected to a terminal connecting the third and fourth switching elements. The multi-level power converter may have a first feedback circuit to generate control signals for setting the switching elements in a plurality of switching states for regulating an output voltage or an output current. The converter may have a second feedback circuit to generate control signals to allow the flying capacitor to be charged or discharged using an inductor current flowing through the inductor.

First claim

What is claimed is:

1. A multi-level power converter comprising:
a first switching element, a second switching element, a third switching element, and a fourth switching element;
an inductor, wherein a first terminal of said inductor is connected to a switching terminal connecting the second switching element and the third switching element;
a flying capacitor, wherein a first terminal of said flying capacitor is connected to a terminal connecting the first switching element and the second switching element, and wherein a second terminal of said flying capacitor is connected to a terminal connecting the third switching element and the fourth switching element;
a first feedback circuit configured to generate control signals for setting the switching elements in a plurality of switching states for regulating an output voltage or an output current of the multi-level power converter; and
a second feedback circuit configured to generate, based on a capacitor voltage across the flying capacitor, temporary control signals for setting the switching elements in a temporary switching state in which the flying capacitor is charged or discharged using an inductor current flowing through the inductor; wherein
the first feedback circuit is configured to generate a first control signal and a second control signal both included within said control signals, the first control signal and the second control signal are configured for correspondingly turning off the first and the second switching elements almost simultaneously, and
the second feedback circuit is configured to select one of the first control signal and the second control signal based on the capacitor voltage, and generate a respective first temporary control signal or second temporary control signal both included within said temporary control signals, by delaying the selected one of the first control signal and the second control signal by a delay interval such that the flying capacitor is charged or discharged by the inductor current during said delay interval.

2. The multi-level power converter of claim 1 , wherein the second feedback circuit is configured to generate said temporary control signals for controlling the switching elements in the temporary switching state during a time interval between a preceding switching state and a subsequent switching state, wherein both the preceding and the subsequent switching states are selected by the first feedback circuit from said plurality of switching states.

3. The multi-level power converter of claim 1 , wherein the temporary switching state of the second feedback circuit is not one of the plurality of switching states of the first feedback circuit.

4. The multi-level power converter of claim 1 , wherein the plurality of switching states includes a first switching state and a second switching state, wherein in the first switching state the first and the second switching elements are turned off and the third and the fourth switching elements are turned on, and wherein in the second switching state the first and the second switching elements are turned on and the third and the fourth switching elements are turned off.

5. The multi-level power converter of claim 1 , wherein the second feedback circuit is configured to determine the delay interval such that a frequency of voltage change of the capacitor voltage is outside of an audible frequency band.

6. The multi-level power converter of claim 1 , wherein the second feedback circuit is configured to
if the capacitor voltage is below a target voltage value, generate the first temporary control signal for turning off the first switching element by delaying the first control signal generated by the first feedback circuit for turning off the first switching element, or
if the capacitor voltage is larger than the target voltage value, generate the second temporary control signal for turning off the second switching element by delaying the second control signal generated by the first feedback circuit for turning off the second switching element.

7. The multi-level power converter of claim 1 , wherein the second feedback circuit is configured to
if the capacitor voltage is below a target voltage value, generate the second temporary control signal for turning off the second switching element by forwarding the second control signal generated by the first feedback circuit for turning off the second switching element, or
if the capacitor voltage is larger than the target voltage value, generate the first temporary control signal for turning off the first switching element by forwarding the first control signal generated by the first feedback circuit for turning off the first switching element.

8. A method of operating a multi-level power converter comprising a first switching element, a second switching element, a third switching element, a fourth switching element, an inductor, and a flying capacitor, wherein a first terminal of said inductor is connected to a switching terminal connecting the second switching element and the third switching element, wherein a first terminal of said flying capacitor is connected to a terminal connecting the first switching element and the second switching element, and wherein a second terminal of said flying capacitor is connected to a terminal connecting the third switching element and the fourth switching element, the method comprising the steps of:
generating, by a first feedback circuit, control signals for setting the switching elements in a plurality of switching states for regulating an output voltage or an output current of the multi-level power converter;
generating, by a second feedback circuit, based on a capacitor voltage across the flying capacitor, temporary control signals for setting the switching elements in a temporary switching state in which the flying capacitor is charged or discharged using an inductor current flowing through the inductor;
generating, by the first feedback circuit, a first control signal and a second control signal both included within said control signals, the first control signal and the second control signal configured for correspondingly turning off the first and the second switching elements almost simultaneously,
selecting, by the second feedback circuit, one of the first control signal and the second control signal based on the capacitor voltage, and generate a respective first temporary control signal or second temporary control signal both included within said temporary control signals, by delaying, by the second feedback circuit, the selected one of the first control signal and the second control signal by a delay interval such that the flying capacitor is charged or discharged by the inductor current during said delay interval.

9. The method of claim 8 , further comprising the step of: - generating, by the second feedback circuit, said temporary control signals for controlling the switching elements in the temporary switching state during a time interval between a preceding switching state and a subsequent switching state, wherein both the preceding and the subsequent switching states are selected by the first feedback circuit from said plurality of switching states.

10. The method according to claim 8 , wherein the temporary switching state of the second feedback circuit is not one of the plurality of switching states of the first feedback circuit.

11. The method according to claim 8 , wherein the plurality of switching states includes a first switching state and a second switching state, wherein in the first switching state the first and the second switching elements are turned off and the third and the fourth switching elements are turned on, and wherein in the second switching st

Assignees

• Dialog Semiconductor Uk Ltd

Inventors

• Mangudi Aravind
• Mercer Mark
• Steele James
• Chang taek
• Mckillop Bill

Classifications

• H02M3/07

  using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps} · CPC title

• H02M3/158 Primary

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02M1/0003

  Details of control, feedback or regulation circuits · CPC title

• H02M1/0032

  Control circuits allowing low power mode operation, e.g. in standby mode · CPC title

• Y02B70/10

  Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes · CPC title