Universal AC adaptor
View Patent ↗Power from an AC source at a source voltage is converted for delivery to a load at a DC load voltage, where the source voltage may vary between a high line voltage and a low line voltage in a normal operating range. DC-DC voltage transformation and isolation are provided in a first power conversion stage, the first stage having a CA input for receiving power from the source and a CA output for delivering a galvanically isolated unregulated AC adapter module (UAAM) voltage. First stage circuitry for performing the first power conversion stage is provided in a self-contained adapter module having input terminals for connection to the AC source and an output connected to the CA output for providing power to a second power conversion stage wherein the second power conversion stage is external to the adapter module.
1. Apparatus comprising:
a safe input for receiving an isolated unipolar input voltage less than 50 volts and characterized by a periodic ripple having a characteristic frequency and a characteristic period;
a DC-DC switching power converter for converting power received from the safe input for delivery to a load via an output, the DC-DC switching power converter comprising one or more switches; and
a controller for operating the one or more switches in a series of converter operating cycles each having a duration that is 1% or less of the characteristic period,
wherein the DC-DC switching power converter is adapted to deliver a controlled output to the load at an output voltage and to adjust an envelope of current drawn by the DC-DC switching power converter to perform power factor correction.
2. The apparatus of claim 1 wherein:
the periodic ripple comprises a series of pulses, the pulses being characterized by a pulse waveform, a pulse duration, and occurring at the characteristic frequency; and
the power factor correction comprises adjusting an envelope of current drawn by the DC-DC switching power converter from the safe input to approximate the pulse waveform.
3. The apparatus of claim 2 wherein the controlled output comprises voltage regulation.
4. The apparatus of claim 2 wherein the controlled output comprises power regulation.
5. The apparatus of claim 1 wherein the output is galvanically coupled to the safe input.
6. The apparatus of claim 1 further comprising an isolation stage having a first input for receiving power from a source at a source voltage and a first output galvanically isolated from the first input connected to supply power to the safe input at a first output voltage, wherein the ratio of first output voltage to first input voltage is essentially fixed.
7. The apparatus of claim 2 further comprising an isolation stage having a first input for receiving power from a source at a source voltage and a first output galvanically isolated from the first input connected to supply power to the safe input at a first output voltage, wherein the ratio of first output voltage to first input voltage is essentially fixed.
8. The apparatus of claim 1 further comprising a first power conversion stage having an input for receiving power from a source and an output connected to supply unregulated power to the input, the input and output of the first power conversion stage being galvanically-isolated from each other.
9. The apparatus of claim 6 wherein the isolation stage comprises a switching power conversion stage.
10. The apparatus of claim 9 wherein the ratio comprises a first value for a first source voltage range and a second value for a second source voltage range.
11. The apparatus of claim 7 wherein the first output voltage is unipolar and the power factor correction comprises adjusting an envelope of current drawn by the DC-DC switching power converter from the safe input to approximate a rectified sinusoid.
12. The apparatus of claim 1 wherein the output voltage is lower than a peak of the voltage applied to the safe input.
13. The apparatus of claim 1 wherein the DC-DC switching power converter comprises a buck-boost converter topology.
14. The apparatus of claim 8 further comprising an enclosure for housing the isolation stage and the DC-DC switching power converter.
15. The apparatus of claim 8 further comprising a first enclosure for housing the isolation stage and a second enclosure for housing the DC-DC switching power converter, wherein the first enclosure is separate and separated by a distance from the second enclosure.
16. A method comprising:
providing an isolated unipolar input voltage less than 50 volts and characterized by a periodic ripple having a characteristic frequency and a characteristic period to a safe input;
converting, using a DC-DC switching power converter, power received from the safe input for delivery to a load via an output, the DC-DC switching power converter comprising one or more switches; and
operating, using a controller, the one or more switches in a series of converter operating cycles each having a duration that is 1% or less of the characteristic period,
wherein the DC-DC switching power converter is adapted to deliver a controlled output to the load at an output voltage and to adjust an envelope of current drawn by the DC-DC switching power converter to perform power factor correction.
17. The method of claim 16 wherein:
the periodic ripple comprises a series of pulses, the pulses being characterized by a pulse waveform, a pulse duration, and occurring at the characteristic frequency; and
the power factor correction comprises adjusting an envelope of current drawn by the DC-DC switching power converter from the safe input to approximate the pulse waveform.
18. The method of claim 17 wherein the controlled output comprises voltage regulation.
19. The method of claim 17 wherein the controlled output comprises power regulation.
20. The method of claim 16 wherein the output is galvanically coupled to the safe input.
21. The method of claim 16 further comprising an isolation stage having a first input for receiving power from a source at a source voltage and a first output galvanically isolated from the first input connected to supply power to the safe input at a first output voltage, wherein the ratio of first output voltage to first input voltage is essentially fixed.
22. The method of claim 17 further comprising an isolation stage having a first input for receiving power from a source at a source voltage and a first output galvanically isolated from the first input connected to supply power to the safe input at a first output voltage, wherein the ratio of first output voltage to first input voltage is essentially fixed.
23. The method of claim 16 further comprising a first power conversion stage having an input for receiving power from a source and an output connected to supply unregulated power to the input, the input and output of the first power conversion stage being galvanically-isolated from each other.
24. The method of claim 21 wherein the isolation stage comprises a switching power conversion stage.
25. The method of claim 24 wherein the ratio comprises a first value for a first source voltage range and a second value for a second source voltage range.
26. The method of claim 22 wherein the first output voltage is unipolar and the power factor correction comprises adjusting an envelope of current drawn by the DC-DC switching power converter from the safe input to approximate a rectified sinusoid.
27. The method of claim 16 wherein the output voltage is lower than a peak of the voltage applied to the safe input.
28. The method of claim 16 wherein the DC-DC switching power converter comprises a buck-boost converter topology.
29. The method of claim 23 further comprising an enclosure for housing the isolation stage and the DC-DC switching power converter.
30. The method of claim 23 further comprising a first enclosure for housing the isolation stage and a second enclosure for housing the DC-DC switching power converter, wherein the first enclosure is separate and separated by a distance from the second enclosure.