Power management integrated circuit partitioning with dedicated primary side control winding

• US 9,184,668 B2
• Filed: 09/11/2013
• Issued: 11/10/2015
• Est. Priority Date: 03/15/2013
• 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): Laxton, Gary L
• Application Number:
  US14/024,514
• Publication Number:
  US 20140268911A1
• Time in Patent Office: 790 Days
• Field of Search: 363/21.06, 363/21.07, 363/21.08, 363/21.14, 363/21.15, 363/21.16, 363/127, 363/21.04, 363/97
• 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 3/33592 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• 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 switched mode power converter having a feedback mechanism by which a coded train of pulses with well defined integrity is generated on a secondary side of the power converter and transmitted to a dedicated control signal winding on the primary side for decoding and application to regulate the power converter output. The control signal winding enables separation of control signal transmission and power transmission resulting in improved processing of the control signal by a primary side controller. The pulse train is modulated by a secondary side controller, transmitted across a transformer and received by the control signal winding, and supplied to the primary side controller. Coded information is included in the coded pulse train by modulating pulses of the pulse train.

Claims

1. A switching mode power converter configured for forward energy transfer from a primary side to a secondary side and for reverse energy transfer from the secondary side to the primary side, the power converter comprising:

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

b) a first switch coupled in series to the primary winding;

c) a first controller coupled to the switch, wherein the first controller is configured to turn the first switch ON and OFF;

d) a second switch coupled in series to the secondary winding;

e) a second controller coupled to the second switch, wherein the second controller is configured to turn the second switch ON and OFF thereby controlling a negative current through the secondary winding;

f) a first auxiliary winding electrically coupled to the first controller and magnetically coupled to the secondary winding to receive a power component of the reverse energy transfer for providing power to the first controller; and

g) a second auxiliary winding electrically coupled to the first controller and magnetically coupled to the secondary winding to receive a control component of the reverse energy transfer for providing a feedback signal to regulate a circuit output characteristic.

2. The power converter of claim 1 wherein the second controller is configured to drive the second switch to generate negative current through the secondary winding to form a coded control signal, further wherein the transformer is configured as a signal transmitter to transmit the coded control signal from the secondary side of the transformer to the primary side of the transformer, wherein the first controller is configured to decode the coded control signal to identify the control information, generate a driving signal according to the control information, and drive the first switch using the driving signal to regulate an output characteristic.

3. The power converter of claim 2 wherein the coded control signal comprises a pulse train signal having a modulated plurality of voltage pulses.

4. The power converter of claim 3 wherein the modulated plurality of pulses is modulated by modulating one or more of a pulse amplitude, a pulse frequency, a pulse width, a pulse delay, and a number of pulse cycles.

5. The power converter of claim 2 wherein the second controller is configured to transmit the coded control signal during an OFF period of the first switch.

6. The power converter of claim 2 wherein the output characteristic is one or more of an output voltage, an output current, and an output power of the power converter.

7. The power converter of claim 1 wherein the coded control signal is based on a sensed output characteristic.

8. The power converter of claim 1 further comprising a sensing circuit coupled to the secondary winding and the second controller, wherein the sensing circuit is configured to sense the output characteristic of the power converter.

9. The power converter of claim 1 wherein the first auxiliary winding has a same polarity as the secondary winding, and the second auxiliary winding has an opposite polarity of the secondary winding.

10. The power converter of claim 5 wherein the forward energy transfer from the primary side of the transformer to the secondary side of the transformer does not induce current in the second auxiliary winding.

11. The power converter of claim 1 wherein the first switch comprises a first transistor and the second switch comprises a second transistor.

12. The power converter of claim 1 further comprising a diode coupled in parallel to the second switch and an output capacitor coupled in series to the diode, wherein the diode is configured to enable current flow from the secondary winding to the output capacitor when forward-biased.

13. The power converter of claim 12 wherein when the second switch is ON, an alternative current path through the second switch is formed between the output capacitor and the secondary winding of the transformer, further wherein a negative secondary current flows from the output capacitor to the secondary winding via the alternative current path.

14. The power converter of claim 1 wherein the second auxiliary winding is configured to provide a sampling signal used for control by the first controller, the sampling signal is provided when the first switch is ON and OFF.

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

a) configuring a switching mode power converter comprising a transformer having a primary winding coupled to an input supply voltage and a secondary winding, a first switch coupled in series to the primary winding, a first controller coupled to the switch, a second switch coupled in series to the secondary winding, a second controller coupled to the second switch, a first auxiliary winding electrically coupled to the first controller and magnetically coupled to the secondary winding, and a second auxiliary winding electrically coupled to the first controller and magnetically coupled to the secondary winding, wherein the first auxiliary winding is dedicated to receive a power transmission for powering the first controller and the second auxiliary winding is dedicated to receive a coded control signal for controlling the first switch;

b) driving the second switch by the second controller to generate the coded control signal;

c) transmitting the coded control signal from the secondary winding to the second auxiliary winding;

d) decoding the coded control signal by the first controller to identify control information;

e) driving the first switch using a driving signal generated according to the control information.

16. The method of claim 15 wherein the first auxiliary winding has a same polarity as the secondary winding, and the second auxiliary winding has an opposite polarity as the secondary winding.

17. The method of claim 16 wherein a forward energy transfer from the primary side of the transformer to the secondary side of the transformer does not induce current in the second auxiliary winding.

18. The method of claim 15 wherein driving the second switch generates negative current through the secondary winding to form the coded control signal.

19. The method of claim 15 wherein the coded control signal comprises a pulse train signal having a modulated plurality of voltage pulses.

20. The method of claim 19 wherein the modulated plurality of pulses is modulated by modulating one or more of a pulse amplitude, a pulse frequency, a pulse width, a pulse delay, and a number of pulse cycles.

21. The method of claim 15 wherein the coded control signal is transmitted during an OFF period of the first switch.

22. The method of claim 15 further comprising measuring an output characteristic of the secondary side of the transformer and coded control signal is generated according to the output characteristic.

23. The method of claim 22 wherein the output characteristic is one or more of an output voltage, an output current, and an output power of the power converter.

24. The method of claim 15 wherein generating the coded control signal comprises generating and applying a driving signal to the second switch to turn the second switch ON and OFF according to a determined pattern resulting in a modulated plurality of voltage pulses across the secondary winding of the transformer.

25. The method of claim 24 wherein turning the second switch ON enables a negative secondary current through the secondary winding.

26. The method of claim 25 wherein enabling the negative secondary current comprises enabling an alternative current path from an output capacitor in the output circuit to the secondary winding.

27. The method of claim 15 wherein the second auxiliary winding provides a sampling signal used for control by the first controller, the sampling signal is provided when the first switch is ON and OFF.