Power regulation for field instruments
View Patent ↗Effective power regulation may be achieved for a field instrument that derives power from a communication signal. In particular aspects, a system and process for power regulation include the ability to receive a communication signal and adjust the voltage supplied to a power converter based on the current of the communication signal. The system and method also include the ability to convert power of the communication signal with the power converter.
1. A power-regulation method for a field instrument, the method comprising:
receiving a communication signal;
adjusting the voltage supplied to a power converter based on the current of the communication signal;
converting power of the communication signal with the power converter using the adjusted supplied voltage;
determining whether the voltage of the communication signal is appropriate; and
if the voltage of the communication signal is not appropriate, refusing to convert power of the communication signal with the power converter.
2. The method of claim 1 , further comprising monitoring the communication signal when it arrives at the field instrument for an inappropriate characteristic.
3. The method of claim 2 , wherein an inappropriate characteristic includes at least one of an inappropriate voltage level, current level, and noise level.
4. The method of claim 2 , further comprising modifying the communication signal to correct the inappropriate signal characteristic.
5. The method of claim 1 , wherein adjusting the voltage supplied to a power converter based on the current of the communication signal comprises:
increasing the voltage if the signal current is low; and
decreasing the voltage if the signal current is high.
6. The method of claim 5 , wherein the voltage is adjusted on an approximately linear basis in relation to the signal current.
7. The method of claim 5 , wherein:
the communication signal is a communication-loop signal;
the supplied voltage is approximately 9 V when the current is approximately 4 mA; and
the supplied voltage is approximately 7 V when the current is approximately 20 mA.
8. The method of claim 1 , further comprising:
determining whether an interruption in the communication signal has occurred; and
if an interruption in the communication signal has occurred, temporarily supplying power to the power converter.
9. The method of claim 1 , further comprising converting power of the communication signal with a second power converter.
10. The method of claim 1 , wherein the communication signal comprises a current-based control signal for the field instrument.
11. A field instrument comprising:
a communication interface operable to receive a communication signal;
a power converter coupled to the communication interface, the power converter operable to convert power of the communication signal using a supplied voltage;
an adjustable voltage regulator coupled to the power converter, the adjustable voltage regulator operable to adjust the voltage supplied to the power converter based on the current of the communication signal; and
a power monitor coupled to the communication interface and the power converter, the power monitor operable to:
determine whether the voltage of the communication signal is appropriate; and
if the voltage of the communication signal is appropriate, allow the power converter to operate.
12. The field instrument of claim 11 , wherein the adjustable voltage regulator is operable to increase the supplied voltage if the signal current is low and decrease the supplied voltage if the signal current is high to adjust the voltage supplied to the power converter based on the current of the communication signal.
13. The field instrument of claim 11 , further comprising a power supply coupled to the communication interface and the power converter, the power supply operable to temporarily supply power to the power converter if the communication signal is interrupted.
14. The field instrument of claim 11 , further comprising a second power converter coupled to the communication interface, the second power converter operable to convert power of the communication signal.
15. The field instrument of claim 11 , wherein the communication signal comprises a current-based control signal for the field instrument.
16. A field instrument comprising:
a communication interface operable to receive a communication-loop signal;
a first power converter coupled to the communication interface, the first power converter operable to convert power of the communication-loop signal;
a second power converter coupled to the communication interface, the second power converter operable to convert power of the communication-loop signal;
an adjustable voltage regulator coupled to the power converters, the adjustable voltage regulator operable to adjust the voltage supplied to the power converters based on the current of the communication-loop signal, the adjustment comprising:
increasing the voltage if the signal current is low, and
decreasing the voltage if the signal current is high;
a power monitor coupled to the communication interface and the power converters, the power monitor operable to:
determine whether the voltage of the communication-loop signal is appropriate, and
if the voltage of the communication-loop signal is appropriate, allow the power converters to operate; and
a power supply coupled to the communication interface and at least one of the power converters, the power supply operable to temporarily supply power to at least one of the power converters if the communication-loop signal is interrupted.
17. A power-regulation method for a field instrument, the method comprising:
receiving a communication signal;
adjusting the voltage supplied to a power converter based on the current of the communication signal;
converting power of the communication signal with the power converter using the adjusted supplied voltage;
determining whether an interruption in the communication signal has occurred; and
if an interruption in the communication signal has occurred, temporarily supplying power to the power converter.
18. The method of claim 17 , further comprising monitoring the communication signal when it arrives at the field instrument for an inappropriate characteristic.
19. The method of claim 18 , wherein an inappropriate characteristic includes at least one of an inappropriate voltage level, current level, and noise level.
20. The method of claim 18 , further comprising modifying the communication signal to correct the inappropriate signal characteristic.
21. The method of claim 17 , wherein adjusting the voltage supplied to a power converter based on the current of the communication signal comprises:
increasing the voltage if the signal current is low; and
decreasing the voltage if the signal current is high.
22. The method of claim 21 , wherein the voltage is adjusted on an approximately linear basis in relation to the signal current.
23. The method of claim 21 , wherein:
the communication signal is a communication-loop signal;
the supplied voltage is approximately 9 V when the current is approximately 4 mA; and
the supplied voltage is approximately 7 V when the current is approximately 20 mA.
24. The method of claim 17 , farther comprising:
determining whether the voltage of the communication signal is appropriate; and
if the voltage of the communication signal is not appropriate, refusing to convert power of the communication signal with the power converter.
25. The method of claim 17 , further comprising converting power of the communication signal with a second power converter.
26. The method of claim 17 , wherein the communication signal comprises a current-based control signal for the field instrument.
27. A field instrument comprising:
a communication interface operable to receive a communication signal;
a power converter coupled to the communication interface, the power converter operable to convert power of the communication signal using a supplied voltage;
an adjustable voltage regulator coupled to the power converter, the adjustable voltage regulator operable to adjust the voltage supplied to the power converter based on the current of the communication signal; and
a power supply coupled to the communication interface and the power converter, the power supply operable to temporarily supply power to the power converter if the communication signal is interrupted.
28. The field instrument of claim 27 , wherein the adjustable voltage regulator is operable to increase the supplied voltage if the signal current is low and decrease the supplied voltage if the signal current is high to adjust the voltage supplied to the power converter based on the current of the communication signal.
29. The field instrument of claim 27 , further comprising a power monitor coupled to the communication interface and the power converter, the power monitor operable to:
determine whether the voltage of the communication signal is appropriate; and
if the voltage of the communication signal is appropriate, allow the power converter to operate.
30. The field instrument of claim 27 , further comprising a second power converter coupled to the communication interface, the second power converter operable to convert power of the communication signal.
31. The field instrument of claim 27 , wherein the communication signal comprises a current-based control signal for the field instrument.