Soft switching circuit, circuit board assembly, and switching power supply

Patent metadata

Field	Value
Publication number	US-2024313629-A1
Application number	US-202118681213-A
Country	US
Kind code	A1
Filing date	Dec 6, 2021
Priority date	Aug 5, 2021
Publication date	Sep 19, 2024
Grant date	—

Abstract

The present disclosure relates to the field of circuit design. The embodiments of the present disclosure provide a soft switch circuit, a circuit board assembly, and a switch power supply. The soft switch circuit includes a power supply, a first switch transistor, a second switch transistor, a third switch transistor, a fourth switch transistor, a capacitor, a main inductor, an auxiliary switch transistor, an auxiliary inductor, and a control unit, wherein the control unit is configured to: if the current of the main inductor is positive, turn on the auxiliary switch transistor before the first switch transistor and the fourth switch transistor are turned on; and if the current of the main inductor is negative, turn on the auxiliary switch transistor before the second switch transistor and the third switch transistor are turned on.

First claim

1 . A soft switch circuit, wherein the soft switch circuit comprises a power supply, a first switch transistor, a second switch transistor, a third switch transistor, a fourth switch transistor, a capacitor, a main inductor, an auxiliary switch transistor, an auxiliary inductor, and a control unit;
a negative electrode of the power supply is grounded, a positive electrode of the power supply is connected to a first end of the first switch transistor, a second end of the first switch transistor is connected to a first end of the second switch transistor and a first end of the main inductor respectively, a second end of the second switch transistor is grounded, a second end of the main inductor is connected to a first end of the third switch transistor and a second end of the fourth switch transistor respectively, a second end of the third switch transistor is grounded, a first end of the fourth switch transistor is connected to a first end of the capacitor, and a second end of the capacitor is grounded, wherein a negative electrode of a body diode of each switch transistor serves as the first end of each switch transistor, and a positive electrode of a body diode of each switch transistor serves as the second end of each switch transistor; the auxiliary switch transistor and the auxiliary inductor are connected in series to form an auxiliary branch circuit, and the auxiliary branch circuit is connected in parallel to the main inductor; the control unit is connected to control ends of the first switch transistor, the second switch transistor, the third switch transistor, the fourth switch transistor, and the auxiliary switch transistor, respectively; and the control unit is configured to, in a case that a current of the main inductor is positive, turn on the auxiliary switch transistor before the first switch transistor and the third switch transistor are turned on; and in a case that the current of the main inductor is negative, turn on the auxiliary switch transistor before the second switch transistor and the fourth switch transistor are turned on.

2 . The soft switch circuit according to claim 1 , wherein,
the control unit is configured to, before the first switch transistor and the third switch transistor are turned on, turn on the auxiliary switch transistor first, and then turn off the second switch transistor and the fourth switch transistor; and before the second switch transistor and the fourth switch transistor are turned on, turn on the auxiliary switch transistor first, and then turn off the first switch transistor and the third switch transistor.

3 . The soft switch circuit according to claim 1 , wherein,
the control unit is configured to, before the first switch transistor and the third switch transistor are turned on, turn off the second switch transistor and the fourth switch transistor first, and then turn on the auxiliary switch transistor; and before the second switch transistor and the fourth switch transistor are turned on, turn off the first switch transistor and the third switch transistor first, and then turn on the auxiliary switch transistor.

4 . The soft switch circuit according to claim 3 , wherein,
the control unit is further configured to turn on the first switch transistor and the third switch transistor at a first preset time interval, and turn on the second switch transistor and the fourth switch transistor at a second preset time interval.

5 . The soft switch circuit according to claim 1 , wherein,
the control unit is further configured to turn off the auxiliary switch transistor after the first switch transistor and the third switch transistor are turned on; and turn off the auxiliary switch transistor after the second switch transistor and the fourth switch transistor are turned on.

6 . The soft switch circuit according to claim 5 , wherein,
the control unit is configured to, after the first switch transistor and the third switch transistor are turned on and in a case that the current on the auxiliary branch circuit is 0, turn off the auxiliary switch transistor; and after the second switch transistor and the fourth switch transistor are turned on and in the case that the current on the auxiliary branch circuit is 0, turn off the auxiliary switch transistor.

7 . The soft switch circuit according to claim 1 , wherein the soft switch circuit further comprises an auxiliary diode;
the auxiliary diode is provided on the auxiliary branch circuit, and a conducting direction of the auxiliary diode on the auxiliary branch circuit is from the second end of the main inductor to the first end of the main inductor.

8 . The soft switch circuit according to claim 1 , wherein the auxiliary switch transistor comprises a first auxiliary MOS transistor and a second auxiliary MOS transistor connected in series;
a conducting direction of the body diode of the first auxiliary MOS transistor on the auxiliary branch circuit is from the first end of the main inductor to the second end of the main inductor, and a conducting direction of the body diode of the second auxiliary MOS transistor on the auxiliary branch circuit is from the second end of the main inductor to the first end of the main inductor; the control unit is configured to, in a case that electric energy is transmitted from the power supply to the capacitor, before the first switch transistor and the third switch transistor are turned on, turn on the first auxiliary MOS transistor and turn off the second auxiliary MOS transistor, and before the second switch transistor and the fourth switch transistor are turned on, turn on the second auxiliary MOS transistor and turn off the first auxiliary MOS transistor; and the control unit is further configured to, in a case that the electric energy is transmitted from the capacitor to the power supply, before the first switch transistor and the third switch transistor are turned on, turn on the second auxiliary MOS transistor and turn off the first auxiliary MOS transistor, and before the second switch transistor and the fourth switch transistor are turned on, turn on the first auxiliary MOS transistor and turn off the second auxiliary MOS transistor.

9 . The soft switch circuit according to claim 1 , wherein the auxiliary inductor is magnetically coupled in parallel to the main inductor.

10 . The soft switch circuit according to claim 1 , wherein the inductance value of the auxiliary inductor is less than the inductance value of the main inductor.

11 . A circuit board assembly, comprising a soft switch circuit, wherein the soft switch circuit comprises a power supply, a first switch transistor, a second switch transistor, a third switch transistor, a fourth switch transistor, a capacitor, a main inductor, an auxiliary switch transistor, an auxiliary inductor, and a control unit;
a negative electrode of the power supply is grounded, a positive electrode of the power supply is connected to a first end of the first switch transistor, a second end of the first switch transistor is connected to a first end of the second switch transistor and a first end of the main inductor respectively, a second end of the second switch transistor is grounded, a second end of the main inductor is connected to a first end of the third switch transistor and a second end of the fourth switch transistor respectively, a second end of the third switch transistor is grounded, a first end of the fourth switch transistor is connected to a first end of the capacitor, and a second end of the capacitor is grounded, wherein a negative electrode of a body diode of each switch transistor serves as the first end of each switch transistor, and a positive electrode of a body diode of each switch transistor serves as

Assignees

• Zte Corp

Inventors

• Wang Linguo
• Zhu Junjie
• Wang Hao

Classifications

• H03K17/133

  in field-effect transistor switches · CPC title

• H03K17/167

  using parallel switching arrangements · CPC title

• H03K2217/0036

  Means reducing energy consumption · CPC title

• H02M3/1582 Primary

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

• H02M1/0064

  Magnetic structures combining different functions, e.g. storage, filtering or transformation · CPC title