Controller and control method used in switched tank converter

Patent metadata

Field	Value
Publication number	US-10972010-B2
Application number	US-201916695101-A
Country	US
Kind code	B2
Filing date	Nov 25, 2019
Priority date	Dec 5, 2018
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

A control method used in a switched tank converter with a first conversion unit, a second conversion unit and a rectification unit, includes: based on current flowing through the resonant tanks in the first and second conversion units, determining when to turn on the high side switches of the first and second conversion units, and when to turn on the low side switches of the first and second conversion units; detecting whether current flowing through the first, second, third and fourth rectification switches crosses zero; and based on the detection result, respectively determining when to turn off the high side switch of the first conversion unit, when to turn off the high side switch of the second conversion unit, when to turn off the low side switch of the second conversion unit, and when to turn off the low side switch of the first conversion unit.

First claim

What is claimed is:

1. A control method used in a switched tank converter, wherein the switched tank converter comprises a first conversion unit, a second conversion unit and a rectification unit, each of the conversion units has a first terminal, a second terminal, a third terminal, a fourth terminal and a switch node, and includes a clamp capacitor coupled between the first and third terminals, a high side switch coupled between the first terminal and the switch node, a low side switch coupled between the switch node and the second terminal, and a resonant tank coupled between the switch node and the fourth terminal; the first terminal of the second conversion unit is coupled to the second terminal of the first conversion unit; the rectification unit includes a first rectification switch, a second rectification switch, a third rectification switch and a fourth rectification switch, each of the rectification switches has a first terminal and a second terminal, the first terminals of the first and fourth rectification switches are coupled to the second terminal of the second conversion unit, the second terminals of the second and third rectification switches are coupled together, the second terminal of the first rectification switch and the first terminal of the third rectification switch are coupled to the fourth terminals of the first and second conversion units, the second terminal of the fourth rectification switch and the first terminal of the second rectification switch are coupled to the third terminal of the second conversion unit; the control method comprises:
based on current flowing through the resonant tanks in the first and second conversion units, determining when to turn on the high side switches of the first and second conversion units, and when to turn on the low side switches of the first and second conversion units;
detecting whether current flowing through the first, second, third and fourth rectification switches crosses zero; and
based on the detection result, respectively determining when to turn off the high side switch of the first conversion unit, when to turn off the high side switch of the second conversion unit, when to turn off the low side switch of the second conversion unit, and when to turn off the low side switch of the first conversion unit.

2. The control method of claim 1 , wherein the first, second, third and fourth rectification switches are all controllable switches.

3. The control method of claim 1 , further comprising:
turning on the high side switches of the first and second conversion units, when the current flowing through the resonant tanks in the first and second conversion units are equal and are respectively flowing out from the corresponding switch node;
turning off the high side switch of the second conversion unit, when a zero cross of the current flowing through the second rectification switch is detected;
turning off the high side switch of the first conversion unit, when a zero cross of the current flowing through the first rectification switch is detected;
turning on the low side switches of the first and second conversion units, when the current flowing through the resonant tanks in the first and second conversion units are equal and are respectively flowing into the corresponding switch node;
turning off the low side switch of the first conversion unit, when a zero cross of the current flowing through the fourth rectification switch is detected; and
turning off the low side switch of the second conversion unit, when a zero cross of the current flowing through the third rectification switch is detected.

4. The control method of claim 1 , further comprising:
turning on the high side switches of the first and second conversion units, when the current flowing through the resonant tanks in the first and second conversion units are detected to have both finished zero cross and changed their direction to flowing out from the corresponding switch node;
turning off the high side switch of the second conversion unit, when a zero cross of the current flowing through the second rectification switch is detected;
turning off the high side switch of the first conversion unit, when a zero cross of the current flowing through the first rectification switch is detected;
turning on the low side switches of the first and second conversion units, when the current flowing through the resonant tanks in the first and second conversion units are detected to have both finished zero cross and changed their direction to flowing into the corresponding switch node;
turning off the low side switch of the first conversion unit, when a zero cross of the current flowing through the fourth rectification switch is detected; and
turning off the low side switch of the second conversion unit, when a zero cross of the current flowing through the third rectification switch is detected.

5. A controller used in a switched tank converter, wherein the switched tank converter having a first conversion unit, a second conversion unit and a rectification unit, each of the conversion units has a first terminal, a second terminal, a third terminal, a fourth terminal and a switch node, and includes a clamp capacitor coupled between the first and third terminals, a high side switch coupled between the first terminal and the switch node, a low side switch coupled between the switch node and the second terminal, and a resonant tank coupled between the switch node and the fourth terminal; the first terminal of the second conversion unit is coupled to the second terminal of the first conversion unit; the rectification unit includes a first rectification switch, a second rectification switch, a third rectification switch and a fourth rectification switch, each of the rectification switches has a first terminal and a second terminal, the first terminals of the first and fourth rectification switches are coupled to the second terminal of the second conversion unit, the second terminals of the second and third rectification switches are coupled together, the second terminal of the first rectification switch and the first terminal of the third rectification switch are coupled to the fourth terminals of the first and second conversion units, the second terminal of the fourth rectification switch and the first terminal of the second rectification switch are coupled to the third terminal of the second conversion unit, the controller comprising:
a turnon determination circuit configured to detect current flowing through the resonant tanks in the first and second conversion units;
a first zero cross detection circuit configured to detect whether the current flowing through the first rectification switch crosses zero;
a second zero cross detection circuit configured to detect whether the current flowing through the second rectification switch crosses zero;
a third zero cross detection circuit configured to detect whether the current flowing through the third rectification switch crosses zero; and
a fourth zero cross detection circuit configured to detect whether the current flowing through the fourth rectification switch crosses zero;
and wherein:
based on the current flowing through the resonant tanks in the first and second conversion units, the controller determines when to turn on the high side switches of the first and second conversion units, and when to turn on the low side switches of the first and second conversion units;
based on the detection results of the first, second, third and fourth zero cross detection circuits, the controller respectively determines when to turn off the high side switch of the first conversion unit, when to turn off the high side switch of the second conversion unit, when to turn off the low side switch of the second conversion unit, and when to turn off the low side switch of th

Assignees

• Chengdu Monolithic Power Sys

Inventors

• Cheng Hao-Chien

Classifications

• H02M3/1588 Primary

  comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence) · CPC title

• H02M3/07 Primary

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

• H02M3/01

  Resonant DC/DC converters · CPC title

• H02M1/0095

  Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck · CPC title

• H02M3/075

  including a plurality of stages and two sets of clock signals, one set for the odd and one set for the even numbered stages · CPC title