METHOD AND APPARATUS FOR INTEGRATED CABLE DROP COMPENSATION OF A POWER CONVERTER

• US 20080246447A1
• Filed: 03/28/2008
• Published: 10/09/2008
• Est. Priority Date: 04/06/2007
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Bircan, Erdem, Djenguerian, Alex B.
• Granted Patent: US 8,035,254 B2
• Time in Patent Office: Days
• US Class Current: 323/234
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 3/33515 with digital control
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

An integrated circuit controller for a power converter to be coupled to a distribution network is disclosed. An example integrated circuit controller according to aspects of the present invention includes a switching control circuit that outputs a drive signal to control switching of a switch to regulate an output of the power converter. The integrated circuit controller also includes a cable drop compensator that outputs a compensated reference voltage signal to the switching control circuit in response to a switching signal. The switching signal is responsive to the drive signal. The compensated reference voltage signal is representative of a voltage value that is responsive to a distribution voltage across the distribution network and a load voltage across a load to be coupled to the distribution network. The switching of the switch is responsive to the compensated reference voltage signal and a feedback signal.

Claims

1. An integrated circuit controller for a power converter to be coupled to a distribution network, comprising:

a switching control circuit that outputs a drive signal to control switching of a switch to regulate an output of the power converter; and

a cable drop compensator that outputs a compensated reference voltage signal to the switching control circuit in response to a switching signal, wherein the switching signal is representative of the drive signal and wherein the compensated reference voltage signal is representative of a voltage value that is responsive to a distribution voltage across the distribution network and a load voltage across a load to be coupled to the distribution network, wherein the switching of the switch is responsive to the compensated reference voltage signal and a feedback signal.

2. The integrated circuit controller of claim 1 further comprising a current limiter coupled to output a current limit reached signal in response to a switch current to flow through the power switch, the switching control circuit coupled to output the drive signal in response to the current limit reached signal.

3. The integrated circuit controller of claim 1 further comprising an oscillator coupled to output a clock signal coupled to be received by the switching control circuit, the switching control circuit coupled to output the drive signal in response to the clock signal.

4. The integrated circuit controller of claim 1 wherein the cable drop compensator comprises:

a switching coefficient calculator coupled to output a switching coefficient signal in response to the switching signal from the switching control circuit; and

a voltage compensation calculator coupled to output the compensated reference voltage signal in response to the switching coefficient signal.

5. The integrated circuit controller of claim 4 wherein the switching coefficient calculator comprises a low pass filter coupled to generate the switching coefficient signal.

6. The integrated circuit controller of claim 4 wherein the voltage compensation calculator is coupled to output the compensated reference voltage signal further in response to a peak current limit adjust signal.

7. The integrated circuit controller of claim 4 wherein the voltage compensation calculator is coupled to output the compensated reference voltage signal further in response to a reference voltage.

8. The integrated circuit controller of claim 1 wherein the switching control circuit and the cable drop compensator are included in a single monolithic device.

9. The integrated circuit controller of claim 8 wherein the single monolithic device further includes the switch.

10. The integrated circuit controller of claim 1 wherein the compensated reference voltage signal is responsive to a sum of the distribution voltage across the distribution network and the load voltage across the load to be coupled to the distribution network.

11. A method for controlling a power converter, comprising:

switching a switch to control a transfer of energy from an input of the power converter to an output of the power converter;

generating a switching coefficient in response to the switching of the switch;

generating a compensated reference voltage signal in response to a reference voltage and the switching coefficient to compensate for a distribution voltage across the distribution network coupled to the output of the power converter and a load voltage across a load coupled to the distribution network; and

controlling the switching of the switch in response to the compensated reference voltage and a feedback signal.

12. The method for controlling the power converter of claim 11 wherein generating the compensated reference voltage signal further includes comprising:

varying a peak current limit of the switch;

calculating a current limit ratio of the switch; and

generating the compensated reference voltage signal further in response to the current limit ratio, the reference voltage and the switching coefficient.

13. The method for controlling the power converter of claim 12 wherein the current limit ratio of the switch is calculated in response to the peak current limit and a maximum peak current limit of the switch.

14. The method for controlling the power converter of claim 11 further comprising galvanically isolating the input of the power converter from the output of the power converter.

15. The method for controlling the power converter of claim 11 further comprising generating the feedback signal in response to sensing a voltage across an auxiliary winding of an energy transfer element of the power converter.

16. A power converter, comprising:

an energy transfer element having an input and an output;

a sensor coupled to the energy transfer element to generate a feedback signal in response to an output of the power converter;

a switching control circuit that outputs a drive signal to control switching of a switch coupled to the energy transfer element to regulate an output of a power converter; and

a cable drop compensator that outputs a compensated reference voltage signal to the switching control circuit in response to a switching signal, wherein the switching signal is representative of the drive signal and wherein the compensated reference voltage signal is representative of a voltage value that is responsive to a distribution voltage across the distribution network and a load voltage across a load to be coupled to the distribution network, wherein the switching of the switch is responsive to the compensated reference voltage signal and a feedback signal.

17. The power converter of claim 16 further comprising a current limiter coupled to output a current limit reached signal in response to a switch current through the power switch, the switching control circuit coupled to output the drive signal in response to the current limit reached signal.

18. The integrated circuit controller of claim 16 wherein the cable drop compensator comprises:

a switching coefficient calculator coupled to output a switching coefficient signal in response to the switching signal from the switching control circuit; and

a voltage compensation calculator coupled to output the compensated reference voltage signal in response to the switching coefficient signal.

19. The integrated circuit controller of claim 18 wherein the voltage compensation calculator is coupled to output the compensated reference voltage signal further in response to a reference voltage.

20. An integrated circuit controller for a power converter to be coupled to a distribution network, comprising:

a switching control circuit that outputs a drive signal to control switching of a switch to regulate an output of a power converter;

a cable drop compensator that outputs a compensated reference voltage signal to the switching control circuit in response to a switching signal, wherein the switching signal is representative of the drive signal and wherein the compensated reference voltage signal is representative of a voltage value that is responsive to a distribution voltage across the distribution network and a load voltage across a load to be coupled to the distribution network; and

a current limiter coupled to output a current limit reached signal in response to a switch current to flow through the power switch, wherein the switching of the switch is responsive to the compensated reference voltage signal, a feedback signal and the current limit reached signal.

21. The integrated circuit controller of claim 20 wherein the cable drop compensator comprises:

a switching coefficient calculator coupled to output a switching coefficient signal in response to the switching signal from the switching control circuit; and

a voltage compensation calculator coupled to output the compensated reference voltage signal in response to the switching coefficient signal.

22. The integrated circuit controller of claim 21 wherein the voltage compensation calculator is coupled to output the compensated reference voltage signal further in response to a reference voltage.

23. An integrated circuit controller for a power converter to be coupled to a distribution network, comprising:

a switching control circuit that outputs a drive signal to control switching of a switch to regulate an output of a power converter;

a cable drop compensator that outputs a compensated reference voltage signal to the switch control circuit in response to a switching signal, wherein the switching signal is representative of the drive signal and wherein the compensated reference voltage signal is representative of a voltage value that is responsive to a distribution voltage across the distribution network and a load voltage across a load to be coupled to the distribution network; and

an oscillator coupled to output a clock signal coupled to be received by the switching control circuit, wherein the switching of the switch is responsive to the compensated reference voltage signal, a feedback signal and the clock signal.

24. The integrated circuit controller of claim 23 wherein the cable drop compensator comprises:

a switching coefficient calculator coupled to output a switching coefficient signal in response to the switching signal from the switching control circuit; and

a voltage compensation calculator coupled to output the compensated reference voltage signal in response to the switching coefficient signal.

25. The integrated circuit controller of claim 24 wherein the voltage compensation calculator is coupled to output the compensated reference voltage signal further in response to a reference voltage.