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CN-122001225-A - Method for operating a power converter, power converter circuit, controller and computer program

CN122001225ACN 122001225 ACN122001225 ACN 122001225ACN-122001225-A

Abstract

The present disclosure relates to a method for operating a power converter, a power converter circuit, a controller and a computer program. The method for operating a power converter includes providing an asymmetric half-bridge flyback converter circuit including a half-bridge having a high-side switch and a low-side switch and a transformer having a primary winding and a secondary winding, the primary winding being connected to the half-bridge, the secondary winding being connected to an output of the power converter, providing a clamp circuit coupled to the primary winding including a third switch and a second diode, providing a controller configured to turn on and off the high-side and low-side switches and the third switch and operate the power converter in a critical conduction mode or a discontinuous conduction mode, turning on the third switch during a third time interval of the discontinuous conduction mode, the high-side and low-side switches being turned off during the third time interval, the clamp circuit preventing free oscillation between transformer magnetizing inductance and parasitic capacitance of the asymmetric half-bridge flyback converter circuit by turning on the third switch.

Inventors

  • ZHANG GUOXING
  • BAI PENGCHENG
  • WANG ZAN

Assignees

  • 英飞凌科技奥地利有限公司

Dates

Publication Date
20260508
Application Date
20251103
Priority Date
20241105

Claims (15)

  1. 1. A method (800) for operating a power converter, the method comprising: Providing an asymmetric half-bridge flyback converter circuit (110), the asymmetric half-bridge flyback converter circuit (110) comprising a half-bridge (114) having a high-side switch (114_1) and a low-side switch (114_2) and a transformer (112) having a primary winding (112_1) and a secondary winding (112_2), wherein the primary winding (112_1) is connected to the half-bridge (114) and the secondary winding is connected to an output of the power converter, Providing a clamping circuit (120), the clamping circuit (120) being coupled to the primary winding (112_1) via an auxiliary winding (112_3) of the transformer (112), wherein the clamping circuit (120) comprises a third switch (122) and a second diode (124) connected in series, Providing a controller (130), the controller (130) being configured to turn on and off the high side switch (114_1) and the low side switch (114_2) and the third switch (122), and to operate the power converter in a critical conduction mode or in a discontinuous conduction mode, and During a third time interval of the discontinuous conduction mode, the third switch (122) is turned on, wherein the high side switch (114_1) and the low side switch (114_2) are turned off during the third time interval, and wherein by turning on the third switch (122), the clamp circuit (120) prevents free oscillation between a magnetizing inductance of the transformer (112) and a parasitic capacitance of the asymmetric half-bridge flyback converter circuit (110).
  2. 2. The method (800) of claim 1, wherein the transformer (112) is arranged on a high side of the half bridge (114).
  3. 3. The method (800) of claim 1, wherein the transformer (112) is arranged on a low side of the half bridge (114).
  4. 4. The method (800) of any preceding claim, further comprising a power circuit (410) for the controller (130), the power circuit (410) comprising a third capacitor (412) and a third diode (414) connected in series, Wherein the power supply circuit (410) is connected to the auxiliary winding (112_3).
  5. 5. The method (800) of any of the preceding claims, wherein the primary winding (112_1) and the secondary winding (112_2) have opposite polarities.
  6. 6. The method (800) of claim 5, wherein the auxiliary winding (112_3) has the same polarity as the secondary winding (112_2).
  7. 7. The method (800) of any of the preceding claims, wherein during the discontinuous conduction mode, the controller (130) is configured to adjust the output power of the power converter using a first control mode or a second control mode. Wherein the first control mode comprises keeping a peak value of a magnetizing current of the transformer (112) constant and adjusting a duration of the third time interval, and Wherein the second control mode comprises keeping the switching frequency of the half bridge (114) constant and adjusting the peak value of the magnetizing current.
  8. 8. A power converter circuit (100, 100') comprising: An asymmetric half-bridge flyback converter circuit (110), the asymmetric half-bridge flyback converter circuit (110) comprising a half-bridge (114) having a high-side switch (114_1) and a low-side switch (114_2) and a transformer (112) having a primary winding (112_1) and a secondary winding (112_2), wherein the primary winding (112_1) is connected to the half-bridge (114) and the secondary winding (112_2) is connected to the output of the power converter circuit (100, 100'), -A clamping circuit (120), the clamping circuit (120) being coupled to the primary winding (112_1) via an auxiliary winding (112_3) of the transformer (112), wherein the clamping circuit (120) comprises a third switch (122) and a second diode (124) connected in series, and A controller (130), the controller (130) being configured to turn on and off the high-side switch (114_1) and the low-side switch (114_2) and the third switch (122), and to operate the power converter circuit (100, 100') in a critical conduction mode or in a discontinuous conduction mode, Wherein during a third time interval of the discontinuous conduction mode, the controller (130) turns on the third switch (122), wherein the high side switch (114_1) and the low side switch (114_2) are turned off during the third time interval, and wherein by turning on the third switch (122), the clamp circuit (120) prevents free oscillation between a magnetizing inductance of the transformer (112) and a parasitic capacitance of the asymmetric half-bridge flyback converter circuit (110).
  9. 9. The power converter circuit (100, 100') of claim 8, wherein the high-side switch (114_1), the low-side switch (114_2), and the third switch (122) are the same type of switch.
  10. 10. The power converter circuit (100, 100') of claim 8 or 9, wherein the primary winding (112_1) and the secondary winding (112_2) have opposite polarities.
  11. 11. The power converter circuit (400, 400') according to any of claims 8-10, further comprising a power supply circuit (410) for the controller (130), the power supply circuit (410) comprising a third capacitor (412) and a third diode (414) connected in series, Wherein the power supply circuit (410) is connected to the auxiliary winding (112_3).
  12. 12. The power converter circuit (100, 100 ') according to any one of claims 8 to 11, wherein during the discontinuous conduction mode, the controller (130) is configured to adjust the output power of the power converter circuit (100, 100') using a first control mode or a second control mode, Wherein the first control mode comprises keeping a peak value of a magnetizing current of the transformer (112) constant and adjusting a duration of the third time interval, and Wherein the second control mode comprises keeping the switching frequency of the half bridge (114) constant and adjusting the peak value of the magnetizing current.
  13. 13. A controller (130) for a power converter circuit (100, 100'), wherein the power converter circuit comprises: An asymmetric half-bridge flyback converter circuit (110), the asymmetric half-bridge flyback converter circuit (110) comprising a half-bridge (114) with a high-side switch (114_1) and a low-side switch (114_2) and a transformer (112) with a primary winding (112_1) and a secondary winding (112_2), wherein the primary winding (112_1) is connected to the half-bridge (114) and the secondary winding (112_2) is connected to the output of the power converter circuit (100, 100'), and -A clamping circuit (120), the clamping circuit (120) being coupled to the primary winding (112_1) via an auxiliary winding (112_3) of the transformer (112), wherein the clamping circuit (120) comprises a third switch (122) and a second diode (124) connected in series, Wherein the controller (130) is configured to turn on and off the high side switch (114_1) and the low side switch (114_2) and the third switch (122), Wherein the controller (130) is configured to operate the power converter circuit (100, 100') in a critical conduction mode or in a discontinuous conduction mode, and Wherein during a third time interval of the discontinuous conduction mode, the controller (130) turns on the third switch (122), wherein the high side switch (114_1) and the low side switch (114_2) are turned off during the third time interval, and wherein by turning on the third switch (122), the clamp circuit (120) prevents free oscillation between a magnetizing inductance of the transformer (112) and a parasitic capacitance of the asymmetric half-bridge flyback converter circuit (110).
  14. 14. The controller (130, 700) of claim 13, wherein the controller (130, 700) comprises an integrated circuit chip (710) or consists of the integrated circuit chip (710).
  15. 15. A computer program (900) comprising instructions which, when executed by a controller (130) of a power converter circuit (100, 100 '), cause the controller (130) to turn on and off a high side switch (114_1), a low side switch (114_2) and a third switch (122) of the power converter circuit (100, 100'), Wherein the power converter circuit (100, 100 ') comprises an asymmetric half-bridge flyback converter circuit (110), the asymmetric half-bridge flyback converter circuit (110) comprising a half-bridge (114) with the high-side switch (114_1) and the low-side switch (114_2) and a transformer (112) with a primary winding (112_1) and a secondary winding (112_2), wherein the primary winding (112_1) is connected to the half-bridge (114) and the secondary winding (112_2) is connected to the output of the power converter circuit (100, 100 '), and wherein the power converter circuit (100, 100 ') further comprises a clamp circuit (120) coupled to the primary winding (112_1) via an auxiliary winding (112_3) of the transformer (112), wherein the clamp circuit (120) comprises the third switch (122) and a second diode (124) connected in series, Wherein the computer program (900) causes the controller (130) to operate the power converter circuit (100, 100 ') in a critical conduction mode or in a discontinuous conduction mode, depending on a load connected to the output of the power converter circuit (100, 100'), and Wherein during a third time interval of the discontinuous conduction mode, the computer program (900) causes the controller (130) to turn on the third switch (122), wherein during the third time interval the high side switch (114_1) and the low side switch (114_2) are turned off, and wherein by turning on the third switch (122), the clamp circuit (120) prevents free oscillation between a magnetizing inductance of the transformer (112) and a parasitic capacitance of the asymmetric half-bridge flyback converter circuit (110).

Description

Method for operating a power converter, power converter circuit, controller and computer program Technical Field The present disclosure relates to a method for operating a power converter, a power converter circuit, a controller for use in a power converter and a computer program for a controller for a power converter circuit. Background The power converter, such as used in charger applications or adapter applications, may, for example, include an asymmetric half-bridge flyback converter circuit. Such an asymmetric half-bridge flyback converter circuit may have one of two possible configurations, a transformer arranged on the high side of the half-bridge or a transformer arranged on the low side of the half-bridge. Furthermore, the asymmetric half-bridge flyback converter circuit may operate in different modes depending on the load connected to the power converter. Below the maximum load, the converter circuit may operate in a discontinuous conduction mode. This mode of operation comprises a time interval during which both the high-side and the low-side switches of the half bridge are turned off, which however means that free oscillations may occur between the magnetizing inductance of the transformer and the parasitic capacitance of the converter circuit. These oscillations may cause additional losses and/or electromagnetic interference (EMI) in the power converter. An improved method for operating a power converter, an improved power converter circuit, an improved controller for a power converter, and an improved computer program for a controller for a power converter circuit may help solve these and other problems. Disclosure of Invention Certain aspects relate to a method for operating a power converter, the method comprising providing an asymmetric half-bridge flyback converter circuit comprising a half-bridge having a high-side switch and a low-side switch and a transformer having a primary winding and a secondary winding, wherein the primary winding is connected to the half-bridge and the secondary winding is connected to an output of the power converter, providing a clamp circuit coupled to the primary winding via an auxiliary winding of the transformer, wherein the clamp circuit comprises a third switch and a second diode connected in series, providing a controller configured to turn on and off the high-side switch and the low-side switch and the third switch and configured to operate the power converter in a critical conduction mode or discontinuous conduction mode, and during a third time interval of the discontinuous conduction mode, turning on the third switch, wherein the high-side switch and the low-side switch are turned off during the third time interval, and wherein by turning on the third switch, the clamp circuit prevents free oscillation between a magnetizing inductance of the transformer and a parasitic capacitance of the asymmetric half-bridge flyback converter circuit. Certain aspects relate to a power converter circuit comprising an asymmetric half-bridge flyback converter circuit comprising a half-bridge having a high-side switch and a low-side switch, and a transformer having a primary winding and a secondary winding, wherein the primary winding is connected to the half-bridge and the secondary winding is connected to an output of the power converter circuit, a clamp circuit coupled to the primary winding via an auxiliary winding of the transformer, wherein the clamp circuit comprises a third switch and a second diode connected in series, and a controller configured to turn on and off the high-side switch and the low-side switch and the third switch, and configured to operate the power converter circuit in a critical conduction mode or discontinuous conduction mode, wherein during a third time interval of the discontinuous conduction mode, the controller turns on the third switch, wherein the high-side switch and the low-side switch are turned off during the third time interval, and wherein by turning on the third switch, the clamp circuit prevents free oscillation between a magnetizing inductance of the transformer and a parasitic capacitance of the asymmetric half-bridge flyback converter circuit. Certain aspects relate to a controller for a power converter circuit, wherein the power converter circuit comprises an asymmetric half-bridge flyback converter circuit comprising a half-bridge having a high-side switch and a low-side switch, and a transformer having a primary winding and a secondary winding, wherein the primary winding is connected to the half-bridge and the secondary winding is connected to an output of the power converter circuit, and a clamp circuit coupled to the primary winding via an auxiliary winding of the transformer, wherein the clamp circuit comprises a third switch and a second diode connected in series, wherein the controller is configured to turn on and off the high-side switch and the low-side switch and the third switch, wherein the controller is config