Power conversion apparatus, control module, and method of operating the same for multi-level output voltage

1. A power conversion apparatus supplying power to a load, the power conversion apparatus comprising:

a power switch,

a transformer having a primary side coupled to the power switch, and a resonance voltage generated on the primary side when the power switch is turned off, and

a control module coupled to the power switch, and configured to alternately turn on and turn off the power switch to convert an input voltage into an output voltage through the transformer, and an auxiliary winding of the transformer configured to sense an auxiliary voltage and configured to provide a level signal corresponding to a voltage level of the output voltage according to the auxiliary voltage, so as to set a predetermined counting threshold according to the level signal, and set a blanking time interval according to a feedback signal related to the load;

wherein, after the blanking time interval ends, the control module counts a number of oscillation turning points presented during an oscillation of the resonance voltage, and turns on the power switch when the number reaches the predetermined counting threshold.

2. The power conversion apparatus as claimed in claim 1 , wherein the control module comprises:

a timing unit configured to set the blanking time interval according to the feedback signal, wherein the feedback signal is generated by detecting the output voltage,

a detection unit coupled to the auxiliary winding, and configured to provide the level signal, and provide at least one pulse, each of the at least one pulse respectively corresponding to one of the oscillation turning points, and

a control unit configured to set the predetermined counting threshold according to the level signal, and increases the number according to each of the at least one pulse presented after the blanking time interval ends.

3. The power conversion apparatus as claimed in claim 2 , wherein the detection unit comprises:

a level detection unit configured to compare the auxiliary voltage with a predetermined level to notify the control unit to set the predetermined counting threshold, and

a turning point detection unit configured to compare the auxiliary voltage with a threshold value to provide the at least one pulse.

4. The power conversion apparatus as claimed in claim 3 , wherein the control unit comprises:

a counting unit coupled to the timing unit and the turning point detection unit, and configured to increase the number in response to each pulse presented after the blanking time interval ends, and trigger to turn on the power switch when the number reaches the predetermined counting threshold.

5. The power conversion apparatus as claimed in claim 2 , wherein the oscillation turning point is a valley turning point; the detection unit provides the at least one pulse corresponding to the resonance voltage at the valley turning point to the control unit, and the control unit increases the number in response to each pulse presented after the blanking time interval.

6. The power conversion apparatus as claimed in claim 2 , wherein the oscillation turning point is a peak turning point; the detection unit provides the at least one pulse corresponding to the resonance voltage at the peak turning point to the control unit, and the control unit increases the number in response to each pulse presented after the blanking time interval.

7. The power conversion apparatus as claimed in claim 2 , wherein a secondary side of the transformer comprises:

a rectifier circuit configured to rectify a power at the secondary side into the output voltage, and

a feedback circuit configured to provide the feedback signal to the control module according to the output voltage.

8. The power conversion apparatus as claimed in claim 2 , wherein the blanking time interval is generated according to a frequency reduction curve, wherein the frequency reduction curve provides a predetermined relationship between the feedback signal and the blanking time interval.

9. The power conversion apparatus as claimed in claim 1 , wherein the power conversion apparatus communicates with the load to determine the voltage level required for the operation of the load.

10. A method of operating a power conversion apparatus, the power conversion apparatus configured to supply power to a load, the method comprising steps of:

alternately turning on and turning off a power switch of the power conversion apparatus to convert an input voltage into an output voltage through a transformer,

sensing an auxiliary voltage through the transformer to provide a level signal corresponding to a voltage level of the output voltage according to the auxiliary voltage,

setting a predetermined counting threshold according to the level signal, and setting a blanking time interval according to a feedback signal, wherein the feedback signal is related to the load,

counting a number of oscillation turning points presented during an oscillation of a resonance voltage after the blanking time interval ends, and

turning on the power switch when the number reaches the predetermined counting threshold.

11. The method as claimed in claim 10 , further comprising steps of:

comparing the output voltage with a reference voltage to generate the feedback signal,

providing at least one pulse, each of the at least one pulse respectively corresponding to one of the oscillation turning points, and

increasing the number of the oscillation turning points according to each of the at least one pulse presented after the blanking time interval ends.

12. The method as claimed in claim 11 , further comprising steps of:

comparing an auxiliary voltage of the transformer with a predetermined level to set the predetermined counting threshold, and

comparing the auxiliary voltage with a threshold value to provide the at least one pulse.

13. The method as claimed in claim 11 , wherein the oscillation turning point is a valley turning point or a peak turning point.

14. The method as claimed in claim 11 , wherein the blanking time interval is generated according to a predetermined relationship between the feedback signal and a frequency reduction curve.

15. The method as claimed in claim 10 , wherein the power conversion apparatus communicates with the load to determine the voltage level required for the operation of the load.

16. A control module configured to alternately turn on and turn off a power switch of a power conversion apparatus to provide an output voltage, the control module comprising:

a timing unit configured to set a blanking time interval according to a feedback signal of the power conversion apparatus, wherein the feedback signal is related to a load,

a detection unit configured to detect a resonance voltage at a primary side of the power conversion apparatus, and configured to detect an auxiliary voltage at the primary side to provide to provide a level signal corresponding to a voltage level of the output voltage according to the auxiliary voltage, and

a control unit coupled to the detection unit, and configured to set a predetermined counting threshold according to the level signal, and count a number of oscillation turning points presented during an oscillation of the resonance voltage after the blanking time interval ends, and turn on the power switch when the number reaches the predetermined counting threshold.