Communication Within A Power Inverter Using Transformer Voltage Frequency

• US 20140133197A1
• Filed: 01/20/2014
• Published: 05/15/2014
• Est. Priority Date: 07/08/2010
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Solarbridge Technologies Incorporated (Totalenergies Se)
• Inventors: Chapman, Patrick L.
• Granted Patent: US 9,509,232 B2
• Time in Patent Office: Days
• US Class Current: 363/37
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• 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 5/458 using semiconductor devices only
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current

Abstract

A power inverter may include a transformer serving as an isolation barrier. The power inverter may include a first controller on one side of the isolation barrier. The first controller may encode the frequency of an input voltage of the transformer with one or more operating conditions of a direct current power supply electrically coupled to the inverter. As second controller on the other side of the isolation barrier may determine a frequency associated with an output voltage of the transformer. The second controller may decode the frequency associated with the output voltage of the transformer to determine the encoded operating conditions.

Claims

1. A power inverter comprising:

a bridge circuit configured to convert an output voltage of a direct-current (DC) power source to an alternating-current (AC) output voltage having an output frequency;

a transformer having a primary side winding and a secondary side winding magnetically coupled to one another, wherein the primary side winding is configured to receive the AC output voltage; and

a first controller having a processor and a memory, wherein the processor is configured to;

determine at least one operating condition of the DC power supply; and

control the output frequency of the AC output voltage in response to the at least one operating condition.

2. The power inverter of claim 1, wherein the memory of the first controller is configured to store a plurality of predetermined operating conditions and a plurality of predetermined frequencies, wherein each of the plurality of predetermined operating conditions corresponds to a respective one of the plurality of predetermined frequencies, wherein the processor of the first controller is configured to:

select one of the predetermined operating conditions from the first table based on the at least one operating condition; and

control the output frequency of the AC output voltage to a predetermined frequency corresponding to the selected one of the operating conditions.

3. The power inverter of claim 1, comprising a second controller having a processor and a memory, the processor configured to:

determine a frequency of a voltage of the secondary winding; and

determine the at least one operating condition based on the frequency of the voltage of the secondary winding.

4. The power inverter of claim 3, wherein the memory of the first controller is configured to store a plurality of predetermined frequencies and a plurality of predetermined operating conditions of the DC power supply, wherein each of the plurality of predetermined frequencies corresponds to a respective one of the plurality of operating conditions, wherein the processor of the second controller is configured to:

select one of the plurality of predetermined frequencies that corresponds to the determined frequency of the voltage of the secondary winding; and

select the predetermined operating condition of the DC power supply that corresponds to the selected one of the plurality of predetermined frequencies.

5. The power inverter of claim 3, wherein power inverter further comprises:

a rectifier configured to rectify the voltage of the secondary winding;

an inverter configured to invert the rectified voltage;

determine a frequency of the inverted voltage; and

determine the at least one operating condition based on the frequency of the inverted voltage.

6. The power inverter of claim 3 further comprising an output bridge circuit having an AC output voltage, wherein the output bridge circuit is configured to supply an AC output voltage to an AC load, wherein the second controller is configured to control a frequency of the AC output voltage of the output bridge circuit based on the at least one operating condition.

7. The power inverter of claim 1, wherein the at least one operating condition is at least one of the output voltage of the DC power source and an output current of the DC power source.

8. The power inverter of claim 1, wherein the first controller and the second controller are electrically isolated from one another.

12. The method of claim 8, wherein encoding the at least one condition in the first frequency of the first alternating-current (AC) voltage comprises encoding the at least one condition in the first frequency of the first alternating-current (AC) voltage for a first predetermined period of time.

13. The method of claim 12, further comprising:

determining at change in the least one condition; and

adjusting, upon expiration of the first predetermined period of time, the first frequency to encode the change in the at least one condition.

14. The method of claim 12, wherein determining the second frequency associated with the second AC voltage comprises determining the second frequency associated with the second AC voltage over a second predetermined period of time.

15. The method of claim 13, wherein the first predetermined period of time is greater than the second predetermined period of time.

16. The method of claim 8, further comprising transmitting the at least one condition subsequent to decoding the second frequency.

9. A method of conveying information through a power converter configured to supply power from a direct current (DC) power source to an alternating current (AC) load, the method comprising:

determining at least one condition;

encoding the at least one condition in a first alternating-current (AC) voltage applied to a first winding of a transformer of the power inverter;

receiving a second AC voltage of a second winding magnetically coupled to the first winding; and

decoding from the second AC voltage the at least one condition.

10. The method of claim 9, wherein determining at least one condition comprises determining at least one operating condition of the DC power source.

11. The method of claim 10, wherein determining at least one operating condition of the DC power source comprises determining at least one of a DC voltage and a DC current produced by the DC power source.

17. A computer-readable medium comprising a plurality of instructions executable by a processor, the computer-readable medium comprising:

instructions to determine at least one operating condition of a DC power source;

instructions to determine a first frequency of a first voltage applied to a first winding of a transformer based on the at least one operating condition;

instructions to determine a second frequency of a second voltage of a second winding of the transformer, wherein the second voltage is induced by application of the first voltage to the first winding; and

instructions to determine the at least one operating condition from the second frequency.

18. The computer-readable medium of claim 17, wherein the instructions to determine the at least one operating condition from the second frequency comprise instructions to determine a number of pulses present in a rectified second voltage over a predetermined period of time.

19. The computer-readable medium of claim 17, wherein the instructions to determine the first frequency of the first voltage applied to the first winding of the transformer based on the at least one operating condition comprise instructions to determine the first frequency based on a predetermined equation.

20. The computer-readable medium of claim 17, wherein the instructions to determine the at least one operating condition from the second frequency comprise instructions to determine the second frequency based on a predetermined equation.