Variable frequency and burst mode operation of primary resonant flyback converters
First Claim
1. A primary resonant flyback converter comprising:
- a primary winding;
a secondary winding magnetically coupled to the primary winding and electrically coupled to an output rectifier, and an output terminal;
a resonant capacitor coupled in series with the primary winding;
a main switch configured to switch on to energize the primary winding and resonant capacitor from a DC voltage bus and to switch off to transfer energy stored in the primary winding to the secondary winding;
an auxiliary switch configured to switch on during an off time of the main switch thereby allowing a resonant current to circulate through the primary winding and the resonant capacitor; and
a control circuit configured to;
vary a duty cycle of the main switch and the auxiliary switch to produce a desired voltage at the output terminal; and
vary a switching frequency of the main switch and the auxiliary switch responsive to a change in output load on the primary resonant flyback converter in combination with at least one of an input voltage into the primary resonant flyback converter and a DC bus voltage of the primary resonant flyback converter.
1 Assignment
0 Petitions
Accused Products
Abstract
A primary resonant flyback converter may include a primary winding, a resonant capacitor in series with the primary winding, a secondary winding magnetically coupled to the primary winding, and an output electrically coupled to the secondary winding. A main switch may be operated to energize the primary winding when closed and transfer energy stored in the primary winding to the secondary winding when open. An auxiliary switch may be configured to switch complimentarily to the main switch, thereby allowing a resonant current to circulate through the primary winding and capacitor. Switch timing may be controlled to produce a desired output voltage. The switching frequency may be varied as a function of output load, input voltage and/or voltage ripple on a DC bus of the converter. Switching may also be temporarily disabled responsive to a decrease in output load and re-enabled responsive to an increase in output load.
35 Citations
20 Claims
-
1. A primary resonant flyback converter comprising:
-
a primary winding; a secondary winding magnetically coupled to the primary winding and electrically coupled to an output rectifier, and an output terminal; a resonant capacitor coupled in series with the primary winding; a main switch configured to switch on to energize the primary winding and resonant capacitor from a DC voltage bus and to switch off to transfer energy stored in the primary winding to the secondary winding; an auxiliary switch configured to switch on during an off time of the main switch thereby allowing a resonant current to circulate through the primary winding and the resonant capacitor; and a control circuit configured to; vary a duty cycle of the main switch and the auxiliary switch to produce a desired voltage at the output terminal; and vary a switching frequency of the main switch and the auxiliary switch responsive to a change in output load on the primary resonant flyback converter in combination with at least one of an input voltage into the primary resonant flyback converter and a DC bus voltage of the primary resonant flyback converter. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A method of operating a power converter, the method comprising:
-
sensing an output voltage of the power converter; sensing at least one of a load on the power converter and an input voltage into the power converter; varying a duty cycle of a main switch of the power converter to produce a desired output voltage; and varying a switching frequency of the main switch responsive to the load on the power converter in combination with at least one of the input voltage into the power converter and a DC voltage bus of the power converter. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. A primary resonant flyback converter comprising:
-
a primary winding; a secondary winding magnetically coupled to the primary winding and electrically coupled to an output rectifier, and an output terminal; a resonant capacitor coupled in series with the primary winding; a main switch configured to switch on to energize the primary winding and resonant capacitor from a DC voltage bus and to switch off to transfer energy stored in the primary winding to the secondary winding; an auxiliary switch configured to switch on during an off time of the main switch thereby allowing a resonant current to circulate through the primary winding and the resonant capacitor; and a control circuit configured to; implement a hysteretic control algorithm to temporarily disable and re-enable operation of the main switch and the auxiliary switch responsive to a decrease in output load on the primary resonant flyback converter. - View Dependent Claims (18, 19, 20)
-
Specification