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CN-121984321-A - Control method of ZVS soft switch

CN121984321ACN 121984321 ACN121984321 ACN 121984321ACN-121984321-A

Abstract

The application discloses a control method of a ZVS soft switch, which utilizes the nonlinear characteristic of a junction capacitor of a switch tube or the reverse recovery characteristic of a silicon tube, and comprises a switch tube Q1, a switch tube Q2, an inductor L1 and a capacitor C1, wherein the switch tube Q1 is provided with the junction capacitor coss and a body diode D1, the switch tube Q2 is provided with the junction capacitor coss and the body diode D2, two ends of the switch tube Q1 are respectively connected with an input power supply, one end of the switch tube Q2 and an intermediate node of one end of the inductor L1, the other end of the inductor L1 is connected with one end of the capacitor C1 and one end of a load, and the other end of the capacitor C1 and the other end of the load are connected with the other end of the switch tube Q2.

Inventors

  • QIU LIWANG
  • Liao Weiye
  • PANG YUQI
  • LAN DONGSHENG

Assignees

  • 广州旭之源科技有限公司

Dates

Publication Date
20260505
Application Date
20260104

Claims (7)

  1. 1. A control method of a ZVS soft switch comprises a switching tube Q1, a switching tube Q2, an energy storage inductor L1 and a capacitor C1, wherein the switching tube Q1 is provided with a junction capacitor coss and a body diode D1 which are connected in parallel, the switching tube Q2 is provided with a junction capacitor coss and a body diode D2 which are connected in parallel, When the current IL1 of the inductor L1 is in a forward falling stage or zero crossing, the driving signal of the switch Q2 is changed from high level to low level to turn off the switch Q2 with zero voltage, the body diode D2 is turned on, the energy of the current IL1 is stored through the junction capacitor coss, after the zero crossing of the current IL1 is changed to negative, the reverse recovery current of the body diode D2 is in the same direction as the current IL1, the energy storage inductor L1 is excited reversely, the junction capacitor coss is charged through the current IL1 of the energy storage inductor L1, and the junction capacitor coss is discharged until the voltage of the switch Q1 is reduced to zero, thereby realizing soft switching of the switch Q1.
  2. 2. The control method of ZVS soft switching according to claim 1, characterized in that the control method comprises the following modes in one time period; the switching tube Q1 is controlled to be conducted, the voltage on the energy storage inductor L1 is the voltage difference between the input voltage and the output voltage, the inductance current increases linearly, and the switching tube Q1 is turned off at the time t1; After the switching tube Q1 is turned off, the current on the energy storage inductor L1 is in a positive direction, the junction capacitor coss of the switching tube Q2 is discharged, meanwhile, the junction capacitor coss1 of the switching tube Q1 is charged, and the voltage Vds2 of the switching tube Q2 is reduced until the voltage Vds2 of the switching tube Q2 is reduced to zero; When the voltage Vds2 of the switching tube Q2 drops to zero, the body diode D2 of the switching tube Q2 is conducted, and the Vds2 voltage of the switching tube Q2 is clamped in a zero voltage state; When the driving signal of the switching tube Q2 becomes high level, the switching tube Q2 is turned on at zero voltage, the current IL1 of the energy storage inductor L1 flows through the switching tube Q2, the voltage at two ends of the energy storage inductor L1 is output voltage, the current IL1 linearly decreases, the switching tube Q2 is turned off at the moment t4, the switching tube Q2 is turned off at zero voltage, and the moment t4 is set at the positive falling stage or zero crossing time of the current IL 1; When the driving signal of the switching tube Q2 becomes low level, the current IL1 of the energy storage inductor L1 is continuously linearly reduced, and the body diode D2 of the switching tube Q2 is conducted; In a mode 6:t5-t6, the current IL1 direction of the energy storage inductor L1 is negative, the junction capacitor coss of the switch tube Q1 is discharged, meanwhile, the junction capacitor coss2 of the switch tube Q2 is charged, the Vds1 voltage of the switch tube Q1 is reduced until the Vds1 voltage of the switch tube Q1 is reduced to zero; In the mode 7:t6-t7, when the Vds1 voltage of the switching tube Q1 drops to zero, the body diode D1 of the switching tube Q1 is conducted, the Vds1 voltage of the switching tube Q1 is clamped in a zero voltage state, and circulation is continued to the mode 1.
  3. 3. A control method of a ZVS soft switch comprises a switching tube Q1, a switching tube Q2, an energy storage inductor L1 and a capacitor C1, wherein the switching tube Q1 is provided with a junction capacitor coss and a body diode D1 which are connected in parallel, the switching tube Q2 is provided with a junction capacitor coss and a body diode D2 which are connected in parallel, and the control method is characterized by further comprising the following steps: The switching tube Q3 is provided with a junction capacitor coss and a body diode D3, the switching tube Q3 is connected with the switching tube Q2 in parallel, and the body diode D3 and the body diode D2 are in the same direction; When the current IL1 of the inductor L1 is in a positive falling stage or zero crossing, the driving signal of the switch Q2 is changed from high level to low level to turn off the switch Q2 with zero voltage, the body diode D3 in the switch Q3 is turned on, the energy of the current IL1 is stored through the junction capacitor coss2 and the junction capacitor coss3, after the zero crossing of the current IL1 is changed to negative direction, the reverse recovery current of the body diode D3 is in the same direction as the current IL1, the energy storage inductor L1 is reversely excited, the junction capacitor coss and the junction capacitor coss are charged by the current IL1 of the energy storage inductor L1, and the junction capacitor coss1 is discharged until the voltage of the switch Q1 is reduced to zero, thereby realizing soft switching of the switch Q1.
  4. 4. A control method of ZVS soft-switching according to claim 3, characterized in that the control method comprises the following modes in one time period; the switching tube Q1 is controlled to be conducted, the voltage on the energy storage inductor L1 is the voltage difference between the input voltage and the output voltage, the inductance current increases linearly, and the switching tube Q1 is turned off at the time t1; After the switching tube Q1 is turned off, the current on the energy storage inductor L1 is in a positive direction, the junction capacitor coss of the switching tube Q2 is discharged, meanwhile, the junction capacitor coss1 of the switching tube Q1 is charged, and the voltage Vds2 of the switching tube Q2 is reduced until the voltage Vds2 of the switching tube Q2 is reduced to zero; When the voltage Vds2 of the switching tube Q2 drops to zero, the body diode D2 of the switching tube Q2 is conducted, and the Vds2 voltage of the switching tube Q2 is clamped in a zero voltage state; When the driving signal of the switching tube Q2 becomes high level, the switching tube Q2 is turned on at zero voltage, the current IL1 of the energy storage inductor L1 flows through the switching tube Q2, the voltage at two ends of the energy storage inductor L1 is output voltage, the current IL1 linearly decreases, the switching tube Q2 is turned off at the moment t4, the switching tube Q2 is turned off at zero voltage, and the moment t4 is set at the positive falling stage or zero crossing time of the current IL 1; when the driving signal of the switching tube Q2 becomes low level, the current IL1 of the energy storage inductor L1 continues to linearly decrease, and the body diode D3 of the switching tube Q3 is conducted; The current IL1 direction of the energy storage inductor L1 is negative, the junction capacitor coss of the switch tube Q1 is discharged, meanwhile, the junction capacitor coss2 of the switch tube Q2 and the junction capacitor coss3 of the switch tube Q3 are charged, the Vds1 voltage of the switch tube Q1 is reduced until the Vds1 voltage of the switch tube Q1 is reduced to zero; Mode 7, t6-t7, when the Vds1 voltage of the switching tube Q1 drops to zero, the body diode D1 of the switching tube Q1 is conducted, the Vds1 voltage of the switching tube Q1 is clamped in a zero voltage state, and circulation is continued to the mode 1.
  5. 5. A ZVS soft switch comprises a switch tube Q1, a switch tube Q2, an inductor L1 and a capacitor C1, wherein the switch tube Q1 is provided with a junction capacitor coss and a body diode D1, the switch tube Q2 is provided with a junction capacitor coss and a body diode D2, one end of the switch tube Q1 is connected with an input power supply, the other end of the switch tube Q1 is connected with one end of the switch tube Q2 and one end of the inductor L1, the other end of the inductor L1 is connected with one end of the capacitor C1 and one end of a load, and the other end of the capacitor C1 and the other end of the load are connected with the other end of the switch tube Q2, and the ZVS soft switch is characterized in that: The switching tube Q2 has reverse recovery characteristics, and the ZVS soft switch is controlled by the control method according to claim 1 or 2.
  6. 6. A ZVS soft switch comprises a switch tube Q1, a switch tube Q2, an inductor L1 and a capacitor C1, wherein the switch tube Q1 is provided with a junction capacitor coss and a body diode D1, the switch tube Q2 is provided with a junction capacitor coss and a body diode D2, one end of the switch tube Q1 is connected with an input power supply, the other end of the switch tube Q1 is connected with one end of the switch tube Q2 and one end of the inductor L1, the other end of the inductor L1 is connected with one end of the capacitor C1 and one end of a load, and the other end of the capacitor C1 and the other end of the load are connected with the other end of the switch tube Q2, and the ZVS soft switch is characterized in that: The switching tube Q3 is provided with a junction capacitor coss and a body diode D3, the switching tube Q3 is connected with the switching tube Q2 in parallel, the body diode D3 and the body diode D2 are in the same direction, the switching tube Q3 is provided with a reverse recovery characteristic, and the ZVS soft switch is controlled by adopting the control method of claim 3 or 4.
  7. 7. The control method of the ZVS soft switch according to claim 6, wherein the switching tube Q2 is a GaN or SiC MOS tube with zero reverse recovery, and the switching tube Q3 is a silicon tube.

Description

Control method of ZVS soft switch Technical Field The application relates to the technical field of switching converters, in particular to a control method of a ZVS soft switch. Background Conventional power conversion systems typically have two technical routes, one being hard switching and one being soft switching. The hard switching circuit has simple structure, convenient control, low efficiency and serious electromagnetic interference, and is not suitable for a power supply system with high power density requirement. The soft switching circuit has the advantages of high conversion efficiency and low electromagnetic interference, and is widely used in the field of high-power electronics. The patent publication CN 114583959B discloses a soft switch MPPT controller and a photovoltaic power system, in which the switching tube is turned off after the inductive current goes from positive to negative, the voltage of the junction capacitor of the other switching tube is extracted from negative by the current, and turned on after the voltage is reset, so as to realize the main tube turn-on. However, although ZVS on can be realized by the control, the switching tube is turned off after the inductor is turned back, the switching tube is turned off hard, and meanwhile, the negative current is larger, and the turn-off loss is larger. Disclosure of Invention The application aims to solve the problems that the existing ZVS control method needs to turn off a switching tube after the energy storage dynamic current is negative current, and the negative current is large and the turn-off loss is large when the switching tube is turned off in a soft mode, and further provides the ZVS control method. In some aspects, the present disclosure provides a control method of a ZVS soft switch, where the ZVS soft switch includes a switching tube Q1, a switching tube Q2, a storage inductor L1, and a capacitor C1, the switching tube Q1 has a junction capacitor coss and a body diode D1 connected in parallel, and the switching tube Q2 has a junction capacitor coss and a body diode D2 connected in parallel. When the current IL1 of the inductor L1 is in a forward falling stage or zero crossing, the driving signal of the switch Q2 is changed from high level to low level to turn off the switch Q2 with zero voltage, the body diode D2 is turned on, the energy of the current IL1 is stored by the junction capacitor coss, after the zero crossing of the current IL1 is changed to negative, the reverse recovery current of the body diode D2 is in the same direction as the current IL1, the energy storage inductor L1 is excited reversely, the junction capacitor coss2 is charged by the current IL1 of the energy storage inductor L1, and the junction capacitor coss is discharged until the voltage of the switch Q1 is reduced to zero, thereby realizing soft switching of the switch Q1. In one alternative, the control method includes the following modalities in one time period; the switching tube Q1 is controlled to be conducted, the voltage on the energy storage inductor L1 is the voltage difference between the input voltage and the output voltage, the inductance current increases linearly, and the switching tube Q1 is turned off at the time t1; After the switching tube Q1 is turned off, the current on the energy storage inductor L1 is in a positive direction, the junction capacitor coss of the switching tube Q2 is discharged, meanwhile, the junction capacitor coss1 of the switching tube Q1 is charged, and the voltage Vds2 of the switching tube Q2 is reduced until the voltage Vds2 of the switching tube Q2 is reduced to zero; When the voltage Vds2 of the switching tube Q2 drops to zero, the body diode D2 of the switching tube Q2 is conducted, and the Vds2 voltage of the switching tube Q2 is clamped in a zero voltage state; When the driving signal of the switching tube Q2 becomes high level, the switching tube Q2 is turned on at zero voltage, the current IL1 of the energy storage inductor L1 flows through the switching tube Q2, the voltage at two ends of the energy storage inductor L1 is output voltage, the current IL1 linearly decreases, the switching tube Q2 is turned off at the moment t4, the switching tube Q2 is turned off at zero voltage, and the moment t4 is set at the positive falling stage or zero crossing time of the current IL 1; When the driving signal of the switching tube Q2 becomes low level, the current IL1 of the energy storage inductor L1 is continuously linearly reduced, and the body diode D2 of the switching tube Q2 is conducted; In a mode 6:t5-t6, the current IL1 direction of the energy storage inductor L1 is negative, the junction capacitor coss of the switch tube Q1 is discharged, meanwhile, the junction capacitor coss2 of the switch tube Q2 is charged, the Vds1 voltage of the switch tube Q1 is reduced until the Vds1 voltage of the switch tube Q1 is reduced to zero; In the mode 7:t6-t7, when the Vds1 voltage of the switching tube Q1 dro