Hold-up time enhancement circuit for LLC resonant converter
First Claim
1. A power conversion system comprising:
- first and second switching elements coupled in series across first and second power input terminals;
an LLC resonant circuit coupled between the first and second switching elements and comprising a first inductor, a primary winding of a transformer, and one or more resonant capacitors;
an output circuit comprising one or more secondary transformer windings and a bulk capacitor coupled across first and second output terminals;
a voltage sensor;
a hold-up time enhancement circuit comprising an auxiliary primary winding of the transformer, a second inductor coupled on a first end to the auxiliary primary winding, and a third switching element coupled to a second end of the second inductor;
a controller coupled to the voltage sensor and effective to determine a hold-up time condition based on a voltage across the voltage sensor;
wherein the controller is further effective in a first operating mode associated with a normal condition to generate switch driver signals to turn OFF the third switching element and disable the hold-up time enhancement circuit; and
the controller is further effective in a second operating mode associated with a hold-up time condition to generate switch driver signals to turn ON the third switching element and enable the hold-up time enhancement circuit wherein an output voltage across the first and second output terminals is increased via current supplied from the auxiliary primary winding.
2 Assignments
0 Petitions
Accused Products
Abstract
An open loop half-bridge LLC power converter includes circuitry to reliably increase hold-up time without sacrificing efficiency. An LLC resonant circuit includes resonant inductance, a primary transformer winding, and resonant capacitance. An auxiliary circuit includes an auxiliary transformer winding, an inductor, and a third switching element coupled in series. A controller is coupled across a voltage sensor and effective thereby to determine a holdup time condition. In a “normal” operating condition the controller generates switch driver signals to turn OFF the third switching element and disable the auxiliary circuit, and in a hold-up time condition the controller turns ON the third switching element and enables the auxiliary circuit wherein the output voltage is increased via current supplied from the auxiliary winding. In various embodiments the auxiliary winding may be an auxiliary primary or secondary, or a secondary to an auxiliary primary winding of a second transformer.
-
Citations
21 Claims
-
1. A power conversion system comprising:
- first and second switching elements coupled in series across first and second power input terminals;
an LLC resonant circuit coupled between the first and second switching elements and comprising a first inductor, a primary winding of a transformer, and one or more resonant capacitors;
an output circuit comprising one or more secondary transformer windings and a bulk capacitor coupled across first and second output terminals;
a voltage sensor;
a hold-up time enhancement circuit comprising an auxiliary primary winding of the transformer, a second inductor coupled on a first end to the auxiliary primary winding, and a third switching element coupled to a second end of the second inductor;
a controller coupled to the voltage sensor and effective to determine a hold-up time condition based on a voltage across the voltage sensor;
wherein the controller is further effective in a first operating mode associated with a normal condition to generate switch driver signals to turn OFF the third switching element and disable the hold-up time enhancement circuit; and
the controller is further effective in a second operating mode associated with a hold-up time condition to generate switch driver signals to turn ON the third switching element and enable the hold-up time enhancement circuit wherein an output voltage across the first and second output terminals is increased via current supplied from the auxiliary primary winding. - View Dependent Claims (2, 3, 4, 5, 6)
- first and second switching elements coupled in series across first and second power input terminals;
-
7. A power conversion system comprising:
- first and second switching elements coupled in series across first and second power input terminals;
an LLC resonant circuit coupled between the first and second switching elements and comprising a first inductor, a primary winding of a transformer, and one or more resonant capacitors;
an output circuit comprising one or more secondary transformer windings, and a bulk capacitor coupled across first and second output terminals;
a voltage sensor;
a hold-up time enhancement circuit comprising an auxiliary secondary winding of the transformer coupled in series with a second inductor and a third switching element; and
a controller coupled to the voltage sensor and effective to determine a hold-up time condition based on a voltage across the voltage sensor, wherein the controller is further effective in a first operating mode associated with a normal condition to generate switch driver signals to turn OFF the third switching element and disable the hold-up time enhancement circuit, the controller is further effective in a second operating mode associated with a hold-up time condition to generate switch driver signals to turn ON the third switching element and enable the hold-up time enhancement circuit to maintain an output voltage across the first and second output terminals at or above a threshold for a period of time during the hold-up time condition, and the hold-up time enhancement circuit is not coupled across the first and second output terminals. - View Dependent Claims (8, 9, 10, 11, 12)
- first and second switching elements coupled in series across first and second power input terminals;
-
13. A power conversion system comprising:
- first and second switching elements coupled in series across first and second power input terminals;
an LLC resonant circuit coupled between the first and second switching elements and comprising a first inductor, a primary winding of a first transformer, and one or more resonant capacitors;
a primary winding of a second transformer coupled in parallel with the primary winding of the first transformer;
an output circuit comprising one or more secondary transformer windings of the first transformer and a bulk capacitor coupled across first and second output terminals;
a voltage sensor;
a hold-up time enhancement circuit further comprising a secondary winding of the second transformer as an auxiliary winding, a second inductor coupled on a first end to the auxiliary winding, and a third switching element coupled to a second end of the second inductor; and
a controller coupled to the voltage sensor and effective to determine a hold-up time condition based on a voltage across the voltage sensor, wherein the controller is further effective in a first operating mode associated with a normal condition to generate switch driver signals to turn OFF the third switching element and disable the hold-up time enhancement circuit, and the controller is further effective in a second operating mode associated with a hold-up time condition to generate switch driver signals to turn ON the third switching element and enable the hold-up time enhancement circuit to maintain an output voltage across the first and second output terminals at or above a threshold for a period of time during the hold-up time condition. - View Dependent Claims (14, 15, 16, 17, 18, 19)
- first and second switching elements coupled in series across first and second power input terminals;
-
20. A power conversion system comprising:
- first and second switching elements coupled in series across first and second power input terminals;
an LLC resonant circuit coupled between the first and second switching elements and comprising a first inductor, a primary winding of a transformer, and one or more resonant capacitors;
an output circuit comprising one or more secondary transformer windings and a bulk capacitor coupled across a first output terminal and a second output terminal;
a voltage sensor;
a hold-up time enhancement circuit comprising a second inductor, an auxiliary secondary winding of the transformer coupled in series with the second inductor, a third switching element, and first and second diodes in each of first and second branches of a diode bridge, anodes of each of the first diodes coupled to the second output terminal, cathodes of each of the second diodes coupled to the second inductor, opposing ends of the auxiliary secondary winding coupled between the first and second diodes of the first and second branches, respectively; and
a controller coupled to the voltage sensor and effective to determine a hold-up time condition based on a voltage across the voltage sensor, wherein the controller is further effective in a first operating mode associated with a normal condition to generate switch driver signals to turn OFF the third switching element and disable the hold-up time enhancement circuit, and the controller is further effective in a second operating mode associated with a hold-up time condition to generate switch driver signals to turn ON the third switching element and enable the hold-up time enhancement circuit to maintain an output voltage across the first and second output terminals at or above a threshold for a period of time during the hold-up time condition.
- first and second switching elements coupled in series across first and second power input terminals;
-
21. A power conversion system comprising:
- first and second switching elements coupled in series across first and second power input terminals;
an LLC resonant circuit coupled between the first and second switching elements and comprising a first inductor, a primary winding of a transformer, and one or more resonant capacitors;
an output circuit comprising first and second secondary transformer windings coupled in series and a bulk capacitor coupled across a first output terminal and a second output terminal, opposing ends of the secondary transformer windings coupled to the first output terminal, the secondary transformer windings including a center tap coupled to the second output terminal;
a voltage sensor;
a hold-up time enhancement circuit comprising a second inductor, an auxiliary secondary winding of the transformer coupled in series with the second inductor and a third switching element, the auxiliary secondary winding coupled on a first end to the second inductor and on a second end to the first output terminal, the third switching element coupled on a first end to the second inductor and on a second end to the second output terminal; and
a controller coupled to the voltage sensor and effective to determine a hold-up time condition based on a voltage across the voltage sensor, wherein the controller is further effective in a first operating mode associated with a normal condition to generate switch driver signals to turn OFF the third switching element and disable the hold-up time enhancement circuit, and the controller is further effective in a second operating mode associated with a hold-up time condition to generate switch driver signals to turn ON the third switching element and enable the hold-up time enhancement circuit to maintain an output voltage across the first and second output terminals at or above a threshold for a period of time during the hold-up time condition.
- first and second switching elements coupled in series across first and second power input terminals;
Specification