CASCADE POWER SYSTEM ARCHITECTURE

• US 20120113692A1
• Filed: 11/09/2010
• Published: 05/10/2012
• Est. Priority Date: 11/09/2010
• Status: Active Grant

• Current Assignee: Flextronics America LLC (Flextronics International Limited)
• Original Assignee: Flextronics America LLC (Flextronics International Limited)
• Inventors: Telefus, Mark, Sharifipour, Bahman
• Granted Patent: US 8,441,810 B2
• Time in Patent Office: Days
• US Class Current: 363/37
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A cascade power system comprises a non-isolated converter in a cascade configuration with an isolated converter and a controller that is coupled with the output of the isolated converter and the switching element of the non-isolated converter. The non-isolated converter steps-down the input voltage to a lower regulated voltage. The isolated converter converts the regulated voltage to a square wave signal that is output to a transformer and the controller. Thus, a the resulting feedback loop comprising the isolated converter, controller and non-isolated converter is completely independent from the output of the system. As a result, a feedback relation can be derived in the form of a feedback algorithm that can effectively regulate/adjust the output of the non-isolated converter and therefore the isolated converter output as well. Further, because the non-isolated converter steps down the voltage and the isolated converter operates on this low stepped down voltage, the system is able to be highly efficient.

Claims

1. A cascade power apparatus comprising:

a. a non-isolated converter having a switching element, wherein the non-isolated converter receives a rectified power signal having an unregulated voltage and generates a regulated voltage;

b. an isolated converter coupled with the non-isolated converter for receiving the regulated voltage and generating a converted voltage;

c. a transformer coupled with the isolated converter for receiving the converted voltage and generating an output voltage; and

d. an internal controller coupled with an output of the isolated converter for receiving the converted voltage and generating a control signal for adjusting the switching element based on a feedback algorithm, wherein the feedback algorithm is independent of the output voltage.

2. The apparatus of claim 1, wherein the non-isolated converter is a step-down converter and the regulated voltage is lower than the unregulated voltage.

3. The apparatus of claim 1, wherein the non-isolated converter is a step-up converter and the regulated voltage is higher than the unregulated voltage.

4. The apparatus of claim 2, wherein the converted voltage is lower than the regulated voltage.

5. The apparatus of claim 4, wherein the converted voltage is a square wave voltage.

6. The apparatus of claim 4, wherein the non-isolated step-down converter is a buck converter.

7. The apparatus of claim 4, wherein the isolated converter is a half-bridge converter.

8. The apparatus of claim 4, further comprising a rectifier for receiving an AC input signal and generating the rectified power signal having the unregulated rectified voltage.

9. The apparatus of claim 8, wherein the rectifier is a diode bridge.

10. The apparatus of claim 4, further comprising an input filter for filtering out electromagnetic and radio frequency interference from the AC input signal.

11. The apparatus of claim 4, further comprising an output filter for filtering out electromagnetic and radio frequency interference from the output voltage.

12. The apparatus of claim 4, wherein adjustment to the switching element controls the output of the non-isolated converter by adjusting a duty cycle of the non-isolated converter.

13. A cascade power system comprising:

a. an electronic device for receiving an output voltage;

b. a power supply for generating an AC input signal; and

c. a power converter coupled between the power supply and the electronic device comprising;

i. a rectifier for receiving the AC input signal and generating a rectified power signal having an unregulated rectified voltage;

ii. a non-isolated converter having a switching element, wherein the non-isolated converter receives the unregulated voltage and generates a regulated voltage;

iii. an isolated converter coupled with the non-isolated converter for receiving the regulated voltage and generating a converted voltage;

iv. a transformer coupled with the isolated converter for receiving the converted voltage and generating the output voltage; and

v. an internal controller coupled with an output of the isolated converter for receiving the converted voltage and generating a control signal for adjusting the switching element based on a feedback algorithm, wherein the feedback algorithm is independent of the output voltage.

14. The system of claim 13, wherein the non-isolated converter is a step-down converter and the regulated voltage is lower than the unregulated voltage.

15. The system of claim 13, wherein the non-isolated converter is a step-up converter and the regulated voltage is higher than the unregulated voltage.

16. The system of claim 14, wherein the converted voltage is lower than the regulated voltage.

17. The system of claim 16, wherein the converted voltage is a square wave voltage.

18. The system of claim 16, wherein the non-isolated step-down converter is a buck converter.

19. The system of claim 16, wherein the isolated converter is a half-bridge converter.

20. The system of claim 16, wherein the rectifier is a diode bridge.

21. The system of claim 16, further comprising an input filter for filtering out electromagnetic and radio frequency interference from the AC input signal.

22. The system of claim 16, further comprising an output filter for filtering out electromagnetic and radio frequency interference from the output voltage.

23. The system of claim 16, wherein adjustment to the switching element controls the output of the non-isolated converter by adjusting a duty cycle of the non-isolated converter.

24. A method of regulating a cascade power apparatus comprising:

a. receiving an unregulated rectified voltage at a non-isolated converter comprising a switching element and generating regulated voltage;

b. receiving the regulated voltage at an isolated converter and generating a converted voltage;

c. receiving the converted voltage at a transformer and generating an output voltage; and

d. receiving the converted voltage at an internal controller and generating a control signal that adjusts the switching element based on a feedback algorithm, wherein the feedback algorithm is independent of the output voltage.

25. The method of claim 24, wherein the non-isolated converter is a step-down converter and the regulated voltage is lower than the unregulated voltage.

26. The method of claim 24, wherein the non-isolated converter is a step-up converter and the regulated voltage is higher than the unregulated voltage.

27. The method of claim 25, wherein the converted voltage is lower than the regulated voltage.

28. The method of claim 27, wherein the converted voltage is a square wave voltage.

29. The method of claim 27, wherein the non-isolated step-down converter is a buck converter.

30. The method of claim 27, wherein the isolated converter is a half-bridge converter.

31. The method of claim 27, further comprising receiving an AC input signal at a rectifier and generating an rectified power signal having the unregulated rectified voltage.

32. The method of claim 31, wherein the rectifier is a diode bridge.

33. The method of claim 27, further comprising filtering out electromagnetic and radio frequency interference from the AC input signal with an input filter.

34. The method of claim 27, further comprising filtering out electromagnetic and radio frequency interference from the output voltage with an output filter.

35. The method of claim 27, wherein adjusting the switching element based on the feedback algorithm comprises varying a duty cycle of the switching element.

36. The method of claim 27, further comprising increasing a power factor of the cascade power apparatus with a power factor correction function of the non-isolated converter.

37. A cascade power apparatus comprising:

a. a rectifier for receiving an AC input signal and generating a rectified power signal having an unregulated rectified voltage;

b. a non-isolated converter having a switching element, wherein the non-isolated converter receives the rectified power signal having the unregulated voltage and generates a regulated voltage;

c. an isolated converter coupled with the non-isolated converter for receiving the regulated voltage and generating a converted voltage;

d. a transformer coupled with the isolated converter for receiving the converted voltage and generating an output voltage; and

e. an internal controller coupled with an output of the isolated converter for receiving the converted voltage and generating a control signal for adjusting the switching element based on a feedback algorithm, wherein the feedback algorithm is independent of the output voltage.

38. The apparatus of claim 37, wherein the non-isolated converter is a step-down converter and the regulated voltage is lower than the unregulated voltage.

39. The apparatus of claim 37, wherein the non-isolated converter is a step-up converter and the regulated voltage is higher than the unregulated voltage.

40. The apparatus of claim 38, wherein the converted voltage is lower than the regulated voltage.

41. The apparatus of claim 40, wherein the non-isolated step-down converter is a buck converter.

42. The apparatus of claim 40, wherein the isolated converter is a half-bridge converter.

43. The apparatus of claim 40, wherein adjustment to the switching element controls the output of the non-isolated converter by adjusting a duty cycle of the non-isolated converter.

44. The apparatus of claim 40, wherein the generated regulated voltage is 50V.

45. The apparatus of claim 40, wherein the generated unregulated voltage is 200V.

46. The apparatus of claim 40, wherein the generated output voltage is either 5, 12 or 24V.