Hysteretic-mode pulse frequency modulated (HM-PFM) resonant AC to DC converter
The disclosed embodiments provide an AC/DC power converter that converts an AC input voltage into a DC output voltage. This AC/DC power converter includes an input rectifier stage which rectifies an AC input voltage into a first rectified voltage. The AC/DC power converter also includes a switching resonant stage which is directly coupled to the output of the input rectifier stage. The switching resonant stage converts the rectified voltage into a first high frequency AC voltage of a first amplitude. This AC/DC power converter additionally includes a transformer which is coupled to the output of the switching resonant stage and is configured to down-convert the first high frequency AC voltage into a second high frequency AC voltage of a second amplitude. Furthermore, the AC/DC power converter includes an output rectifier stage which is coupled to the output of the transformer, wherein the output rectifier stage rectifies the second high frequency AC voltage into a DC output voltage.
1. A power converter, comprising:
an input-rectifier stage configured to rectify a first AC voltage into a first DC voltage;
a switching stage coupled to an output of the input-rectifier stage, the switching stage configured to convert the first DC voltage into a second AC voltage;
a resonant stage coupled to an output of the switching stage, the resonant stage configured to convert the second AC voltage into a third AC voltage;
an output-rectifier stage coupled to an output of the resonant stage, the output-rectifier stage configured to rectify the third AC voltage into a second DC voltage; and
a controller coupled to an output of the output-rectifier stage and to an input of the switching stage, wherein the controller is configured to:
receive a first measurement representative of the first DC voltage;
receive a second measurement representative of the second DC voltage;
generate one or more control signals based on a comparison between the second measurement and a reference voltage, wherein the one or more control signals drive the switching stage; and
set a driving frequency of the one or more control signals based on the first measurement and a lookup table.
2. The power converter of claim 1 , wherein the resonant stage comprises a transformer and a capacitor.
3. The power converter of claim 2 , wherein:
the controller is further configured to vary the driving frequency of the one or more control signals between a base frequency and a peak frequency;
the base frequency corresponds to a zero position of the first measurement; and
the peak frequency corresponds to a peak position of the first measurement.
4. The power converter of claim 3 , wherein the lookup table is determined based on the base frequency, the peak frequency, the reference voltage, and a gain curve of the resonant stage at a load condition of the power converter.
5. The power converter of claim 4 , wherein the gain curve of the resonant stage is determined based on values of the transformer and the capacitor of the resonant stage.
6. The power converter of claim 4 , wherein the gain curve of the resonant stage is determined based on a measured characteristic gain of the resonant stage.
7. The power converter of claim 5 , wherein the controller is further configured to determine the reference voltage based on the peak frequency and a peak amplitude of the first AC voltage.
8. The power converter of claim 7 , wherein the controller is further configured to synchronize the driving frequency of the one or more control signals based on a zero-cross detection of the first measurement.
9. A power supply, comprising:
an AC power connector; and
a power converter coupled to the AC power connector, the power converter comprising:
an input-rectifier stage configured to rectify a first AC voltage into a first DC voltage;
a switching stage coupled to an output of the input-rectifier stage, the switching stage configured to convert the first DC voltage into a second AC voltage;
a resonant stage coupled to an output of the switching stage, the resonant stage configured to convert the second AC voltage into a third AC voltage;
an output-rectifier stage coupled to an output of the resonant stage, the output-rectifier stage configured to rectify the third AC voltage into a second DC voltage; and
a controller coupled to an output of the output-rectifier stage and to an input of the switching stage, wherein the controller is configured to:
receive a first measurement representative of the first DC voltage;
receive a second measurement representative of the second DC voltage;
generate one or more control signals based on a comparison between the second measurement and a reference voltage, wherein the one or more control signals drive the switching stage; and
set a driving frequency of the one or more control signals based on the first measurement and a lookup table.
10. The power supply of claim 9 , wherein the resonant stage comprises a transformer and a capacitor.
11. The power supply of claim 10 , wherein:
the controller is further configured to vary the driving frequency of the one or more control signals between a base frequency and a peak frequency;
the base frequency corresponds to a zero position of the first measurement; and
the peak frequency corresponds to a peak position of the first measurement.
12. The power supply of claim 11 , wherein the lookup table is determined based on the base frequency, the peak frequency, the reference voltage, and a gain curve of the resonant stage at a load condition of the power converter.
13. The power supply of claim 12 , wherein the gain curve of the resonant stage is determined based on values of the transformer and the capacitor of the resonant stage.
14. The power supply of claim 12 , wherein the gain curve of the resonant stage is determined based on a measured characteristic gain of the resonant stage.
15. The power supply of claim 13 , wherein the controller is further configured to determine the reference voltage based on the peak frequency and a peak amplitude of the first AC voltage.
16. The power supply of claim 15 , wherein the controller is further configured to synchronize the driving frequency of the one or more control signals based on a zero-cross detection of the first measurement.
17. A method for converting an AC input voltage into a DC output voltage, comprising:
rectifying a first AC voltage into a first DC voltage using an input-rectifier stage;
converting the first DC voltage into a second AC voltage using a switching stage;
converting the second AC voltage into a third AC voltage using a resonant stage, the resonant stage including a transformer and a capacitor;
rectifying the third AC voltage into a DC output voltage using an output-rectifier stage;
generating, by providing a controller, one or more control signals; and
driving the switching stage in accordance with the one or more control signals,
wherein the controller is coupled to an output of the output-rectifier stage and to an input of the switching stage; and
wherein the controller is configured to:
receive a first measurement representative of the first DC voltage;
receive a second measurement representative of the second DC voltage;
generate the one or more control signals based on a comparison between the second measurement and a reference voltage; and
set a driving frequency of the one or more control signals based on the first measurement and information of a lookup table.
18. The method of claim 17 , wherein:
the controller is further configured to vary the driving frequency of the one or more control signals between a base frequency and a peak frequency;
the base frequency corresponds to a zero position of the first measurement; and
the peak frequency corresponds to a peak position of the first measurement.
19. The method of claim 18 , wherein the lookup table is determined based on the base frequency, the peak frequency, the reference voltage, and a gain curve of the resonant stage at a load condition.
20. The method of claim 19 , wherein:
the gain curve of the resonant stage is determined based on values of the transformer and the capacitor of the resonant stage;
the controller is further configured to determine the reference voltage based on the peak frequency and a peak amplitude of the first AC voltage; and
the controller is further configured to synchronize the driving frequency of the one or more control signals based on a zero-cross detection of the first measurement.