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US 12,113,448 B2Granted
Zero-voltage-switching flyback converter with reduced secondary side current and voltage stress
AssigneeDialog Semiconductor (UK) Limited
InventorsHuaming Guo, Yi Xu, Zhaowu Luo, Yongcai Lai, Jianming Yao
Life of this patent
Estimating the term…
Abstract
A flyback converter is provided in which either auxiliary winding or the primary winding is split into two windings. In this fashion, a different turn ratio is presented to the secondary winding during the transformer reset period as compared to when an active-clamp transistor or a ZVS switch transistor is switched on.
Claims20
A zero-voltage switching (ZVS) flyback converter, comprising:
- a transformer having a primary winding, a secondary winding, a first auxiliary winding, and a second auxiliary winding;
- an SR switch transistor in series with the secondary winding;
- a first diode;
- an auxiliary capacitor in series with the first auxiliary winding and the first diode, wherein the first diode is configured to allow a charging current to flow from a positive terminal of the first auxiliary winding into a positive terminal of the auxiliary capacitor and to prevent a current flow into the positive terminal of the first auxiliary winding;
- a second diode;
- and
- a ZVS switch transistor in series with the second auxiliary winding and the second diode, wherein the second diode is configured to allow a discharging current to flow from the positive terminal of the auxiliary capacitor through the second auxiliary winding while the ZVS switch transistor is on and to prevent a current flow through the second auxiliary winding while the charging current is conducting.
4 more elements
A zero-voltage switching (ZVS) flyback converter, comprising:
- a transformer having a primary winding, a secondary winding, a first auxiliary winding, and a second auxiliary winding;
- an SR switch transistor in series with the secondary winding;
- a first diode;
- an auxiliary capacitor in series with the first auxiliary winding and the first diode, wherein the first diode is configured to allow a charging current to flow from a positive terminal of the first auxiliary winding into a positive terminal of the auxiliary capacitor;
- a second diode;
- and
- a ZVS switch transistor in series with the first auxiliary winding, the second auxiliary winding and the second diode, wherein the second diode is configured to allow a discharging current to flow from the positive terminal of the auxiliary capacitor through the first auxiliary winding and through the second auxiliary winding while the ZVS switch transistor is on.
4 more elements
A method of operation for a ZVS flyback converter, comprising:
- switching on an SR switch transistor coupled to a secondary winding of a transformer for an SR switch transistor on-time period;
- charging an auxiliary capacitor to a peak voltage by conducting a charging current through a first auxiliary winding of the transformer responsive to the switching on of the SR switch transistor;
- and
- switching on a ZVS switch transistor for a ZVS switch transistor on-time period to cause the auxiliary capacitor to discharge from the peak voltage by conducting a discharging current from the auxiliary capacitor to ground through a second auxiliary winding of the transformer.
1 more element
An active-clamp flyback converter, comprising:
- a transformer having a primary winding, an auxiliary winding, and a secondary winding;
- an active-clamp capacitor;
- an input voltage rail coupled to a negative terminal of the primary winding and to a negative terminal of the active-clamp capacitor;
- a power switch transistor coupled between a positive terminal of the primary winding and ground;
- an active-clamp transistor coupled between the positive terminal of the primary winding and a negative terminal of the auxiliary winding, the auxiliary winding having a positive terminal coupled to a positive terminal of the active-clamp capacitor;
- and
- a diode coupled between the positive terminal of the primary winding and the positive terminal of the auxiliary winding.
4 more elements
Dependencies are inferred from the claim text.