Current controlled resonant tank circuit

• US 9,515,560 B1
• Filed: 08/07/2015
• Issued: 12/06/2016
• Est. Priority Date: 08/08/2014
• Status: Active Grant

• Current Assignee: Flextronics America LLC (Flextronics International Limited)
• Original Assignee: Flextronics America LLC (Flextronics International Limited)
• Inventors: Ramos Yeo, Peter, Navarro, Aldimarl Mantilla, Telefus, Mark, Sharifipour, Bahman
• Primary Examiner(s): Laxton, Gary L
• Application Number:
  US14/821,524
• Time in Patent Office: 487 Days
• US Class Current: 1/1
• CPC Class Codes: H02M 1/0054 Transistor switching losses periodically suspending operation of switching converter in low power mode H02M1/0035
• 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 1/0074 Plural converter units whose inputs are connected in series
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H03F 2200/391 the output circuit of an amplifying stage comprising an LC-network
• CPC Class Codes: H03F 2203/21157 A filter circuit being added at the output of a power amplifier stage
• CPC Class Codes: H03F 3/2176 Class E amplifiers
• 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 includes a non-isolated buck converter in cascade with an isolated Class-E resonant circuit, where the Class-E resonant circuit operates at high frequency, for example 4 Mhz. Further, the non-isolated buck converter is configured as a current source coupled to the Class-E resonant circuit which provides a buck converter output voltage as input to the Class-E resonant circuit. The Class-E resonant circuit includes capacitive isolation for the cascade power system output. The cascade power system further includes a feedback control circuit for regulating a system output voltage. A feedback signal is used to adjust a duty cycle of the buck converter, thereby adjusting a buck converter output voltage. The buck converter output voltage is provided as input to the Class-E resonant circuit.

Claims

1. A power converter comprising:

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

b. an isolated Class-E amplifier having a second switching element, wherein the isolated Class-E amplifier is coupled with the non-isolated buck converter for receiving the buck converter output voltage and generating a converted voltage;

c. a galvanic isolation circuit coupled with the isolated Class-E amplifier for receiving the converted voltage and generating an output voltage;

d. a current loop comprising an inductor, a capacitor and a diode coupled in series, wherein the capacitor is coupled to the isolated Class-E amplifier, a first terminal of the inductor is coupled to the Class-E amplifier and a second terminal of the inductor is coupled to the non-isolated buck converter; and

d. a feedback control circuit coupled to sense the output voltage and to provide a corresponding signal to the non-isolated buck converter so as to regulate the output voltage by turning ON and OFF the first switching element, wherein when the first switching element is turned ON energy is stored in the inductor and when the first switching element is turned OFF energy stored in the inductor induces a current loop current from the inductor to the capacitor that charges the capacitor, and a resulting energy stored in the capacitor is transferred by the isolated Class-E amplifier through the galvanic isolation circuit.

2. The power converter of claim 1 further comprising a resonant tank circuit coupled between the isolated Class-E amplifier and the galvanic isolation circuit.

3. The power converter of claim 1 wherein the converted voltage is a square wave voltage.

4. The power converter of claim 1 wherein the first switching element and the second switching element each comprise a transistor.

5. The power converter of claim 1 wherein the isolated Class-E resonant circuit comprises a single transistor.

6. The power converter of claim 1 wherein the second switching element operates at a switching frequency of about 4 Mhz.

7. The power converter of claim 1 further comprising an input rectifier for receiving an AC input signal and generating the rectified power signal having the unregulated voltage.

8. The power converter of claim 7 wherein the input rectifier comprises a diode bridge.

9. The power converter of claim 7 further comprising an input filter for filtering out electromagnetic and radio frequency interference from the AC input signal.

10. The power converter of claim 1 further comprising an output rectifier for receiving the output voltage from the capacitive isolation circuit and generating a rectified DC output voltage.

11. The power converter of claim 10 wherein the output rectifier comprises a diode bridge.

12. The power converter of claim 10 further comprising an output filter for filtering out electromagnetic and radio frequency interference from the output voltage.

13. The power converter of claim 1 wherein the feedback control circuit comprises a voltage divider to sense the output voltage.

14. The power converter of claim 1 wherein the feedback control circuit comprises an optical coupler circuit to provide the corresponding signal across the galvanic isolation circuit to the non-isolated buck converter.

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

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

iii. an isolated Class-E amplifier having a second switching element, wherein the isolated Class-E amplifier is coupled with the non-isolated buck converter for receiving the buck converter output voltage and generating a converted voltage;

iv. a galvanic isolation circuit coupled with the isolated Class-E amplifier for receiving the converted voltage and generating an output voltage;

v. a current loop comprising an inductor, a capacitor and a diode coupled in series, wherein the capacitor is coupled to the isolated Class-E amplifier, a first terminal of the inductor is coupled to the Class-E amplifier and a second terminal of the inductor is coupled to the non-isolated buck converter; and

vi. a feedback control circuit coupled to sense the output voltage and to provide a corresponding signal to the non-isolated buck converter so as to regulate the output voltage by turning ON and OFF the first switching element, wherein when the first switching element is turned ON energy is stored in the inductor and when the first switching element is turned OFF energy stored in the inductor induces a current loop current from the inductor to the capacitor that charges the capacitor, and a resulting energy stored in the capacitor is transferred by the isolated Class-E amplifier through the galvanic isolation circuit.

16. The power system of claim 15 further comprising a resonant tank circuit coupled between the isolated Class-E amplifier and the galvanic isolation circuit.

17. The power system of claim 15 wherein the converted voltage is a square wave voltage.

18. The power system of claim 15 wherein the first switching element and the second switching element each comprise a transistor.

19. The power system of claim 15 wherein the isolated Class-E resonant circuit comprises a single transistor.

20. The power system of claim 15 wherein the second switching element operates at a switching frequency of about 4 Mhz.

21. The power system of claim 15 wherein the input rectifier comprises a diode bridge.

22. The power system of claim 15 further comprising an input filter for filtering out electromagnetic and radio frequency interference from the AC input signal.

23. The power system of claim 15 further comprising an output rectifier coupled between the galvanic isolation circuit and the electronic device.

24. The power system of claim 23 wherein the output rectifier comprises a diode bridge.

25. The power system of claim 23 further comprising an output filter for filtering out electromagnetic and radio frequency interference from the output voltage.

26. The power system of claim 15 wherein the feedback control circuit comprises a voltage divider to sense the output voltage.

27. The power system of claim 15 wherein the feedback control circuit comprises an optical coupler circuit to provide the corresponding signal across the galvanic isolation circuit to the non-isolated buck converter.