Reconstruction pulse shape integrity in feedback control environment

• US 9,312,775 B2
• Filed: 04/17/2013
• Issued: 04/12/2016
• Est. Priority Date: 08/15/2012
• Status: Active Grant

• Current Assignee: Flextronics America LLC (Flextronics International Limited)
• Original Assignee: Flextronics America LLC (Flextronics International Limited)
• Inventors: Telefus, Mark
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US13/865,010
• Publication Number:
  US 20140204622A1
• Time in Patent Office: 1,091 Days
• Field of Search: 363/21.02, 363/21.03, 363/21.12, 363/21.13, 363/21.15, 363/21.16
• US Class Current: 1/1
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer

Abstract

A switched mode power converter includes a closed loop feedback control mechanism for regulating an output characteristic and a resonant type circuit for inclusion of resonant energy delivery. The characteristic impedance of the resonant type circuit is modified from an optimal energy transfer configuration to one that dampens fluctuations in a feedback signal used by the closed loop feedback mechanism. The modified characteristic impedance functions to dampen those fluctuations in the feedback signal resulting from leakage inductance energy provided by the resonant type circuit.

Claims

1. A method of controlling a switching mode power converter comprising:

a. configuring a switching mode power converter comprising a transformer, an output circuit coupled to a secondary winding of the transformer, a main switch coupled to a primary winding of the transformer, a controller coupled to the main switch, a feedback circuit including an auxiliary winding magnetically coupled to the secondary winding, and a resonant type circuit coupled to the primary winding to form a resonant tank, wherein the resonant type circuit comprises a pair of capacitors configured with a capacitance ratio and a resistive element, further wherein the resonant type circuit further comprises a shape generating circuit configured to shape the feedback signal to have a back end that is substantially linear;

b. configuring the capacitance ratio and the resistive element in the resonant tank to have a characteristic impedance that dampens fluctuations in a feedback signal received from the output circuit by the controller via the auxiliary winding and shapes the feedback signal to have the back end that is substantially linear; and

c. generating a driving signal according to the received feedback signal; and

d. driving the main switch using the driving signal to regulate an output characteristic.

2. The method of claim 1 wherein the feedback signal is a voltage signal that is proportional in value to an output voltage of the power converter.

3. The method of claim 1 wherein the output characteristic is one or more of an output voltage, an output current, and an output power of the power converter.

4. The method of claim 1 wherein dampening fluctuations in the feedback signal improves a pulse shape integrity of the feedback signal.

5. The method of claim 1 wherein the dampened fluctuations are those fluctuations resulting from leakage inductance energy provided by the resonant tank.

6. The method of claim 1 wherein configuring the switching mode power converter further comprises configuring the resonant type circuit to include an auxiliary switch coupled in parallel to the primary winding such that when the auxiliary switch is turned ON the resonant tank is established.

7. The method of claim 6 wherein configuring the switching mode power converter further comprises configuring the resonant type circuit to include a driving circuit coupled to the auxiliary switch, wherein the driving circuit is parametrically driven by a voltage condition across the primary winding of the transformer.

8. The method of claim 1 wherein the characteristic impedance of the resonant tank is configured to dampen fluctuations in the feedback signal by adjusting a capacitance ratio within the resonant type circuit so as to reduce an amount of resonant energy delivered to the output circuit.

9. The method of claim 1 wherein the characteristic impedance of the resonant tank is configured to dampen fluctuations in the feedback signal by adding a resistive element within the resonant tank so as to reduce an amount of resonant energy delivered to the output circuit.

10. The method of claim 1 further comprising transmitting the feedback voltage signal from the output circuit to the first controller via the auxiliary winding.

11. A switching mode power converter comprising:

a. a transformer having a primary winding coupled to an input supply voltage and a secondary winding;

b. a switch coupled in series to the primary winding;

c. a controller coupled to the switch;

d. a feedback circuit including an auxiliary winding magnetically coupled to the secondary winding to receive a feedback signal, wherein the feedback circuit is coupled to the controller to provide the feedback signal; and

e. a resonant type circuit coupled to the primary winding to form a resonant tank, wherein the transformer and the resonant type circuit are configured such that the resonant tank has a characteristic impedance that dampens fluctuations in the feedback signal, further wherein the resonant type circuit comprises a pair of capacitors configured with a capacitance ratio and a resistive element included within the resonant tank, wherein the capacitance ratio and the resistive element are configured to achieve the characteristic impedance, further wherein the resonant type circuit further comprises a shape generating circuit configured to shape the feedback signal to have a back end that is substantially linear.

12. The power converter of claim 11 wherein the feedback signal is a voltage signal that is proportional in value to an output voltage of the power converter.

13. The power converter of claim 11 wherein the output characteristic is one or more of an output voltage, an output current, and an output power of the power converter.

14. The power converter of claim 11 wherein the dampened fluctuations are those fluctuations resulting from leakage inductance energy provided by the resonant tank.

15. The power converter of claim 11 wherein the resonant type circuit comprises an auxiliary switch coupled in parallel to the primary winding such that when the auxiliary switch is turned ON the resonant tank is established.

16. The power converter of claim 15 wherein the resonant type circuit further comprises a driving circuit coupled to the auxiliary switch of the resonant tank, wherein the driving circuit is parametrically driven to turn ON and OFF the auxiliary switch by a voltage condition across the primary winding of the transformer.

17. The power converter of claim 15 wherein the auxiliary switch comprises a transistor.

18. The power converter of claim 11 wherein the capacitance ratio is 1:

1.

19. The power converter of claim 11 wherein the transformer is configured to transmit the feedback signal from the secondary winding to the auxiliary winding.

20. The power converter of claim 11 wherein the switch comprises a transistor.

23. The power converter of claim 11 wherein the resonant type circuit comprises a shape generating circuit configured to shape the feedback signal to have a back end that is substantially linear.

21. A switching mode power converter comprising:

a. a transformer having a primary winding coupled to an input supply voltage and a secondary winding;

b. a switch coupled in series to the primary winding;

c. a controller coupled to the switch;

d. a feedback circuit including an auxiliary winding magnetically coupled to the secondary winding to receive a feedback signal, wherein the feedback circuit is coupled to the controller to provide the feedback signal; and

e. a resonant type circuit coupled to the primary winding to form a resonant tank, wherein the transformer and the resonant type circuit are configured such that the resonant tank has a characteristic impedance that dampens fluctuations in the feedback signal, further wherein the resonant type circuit further comprises a resistive element included within the resonant tank that achieves the characteristic impedance, further wherein the resonant type circuit further comprises a shape generating circuit configured to shape the feedback signal to have a back end that is substantially linear.

22. The power converter of claim 21 wherein the resistive element comprises a resistor, further wherein the resistor is coupled to a common node between the primary winding and the switch.