Ethernet-APL field device having reduced energy consumption
A field device for an industrial process includes field device circuitry, an APL communication circuit, and a power circuit. The power circuit includes a power regulator configured to regulate DC power that powers the field device circuitry and the APL communication circuit, a main power sensor configured to generate a main power signal that corresponds to the DC power, a voltage shunt regulator configured to divert excess power to a circuit common, and an excess power sensor configured to generate an excess power signal that corresponds to a magnitude of the excess power. The power regulator adjusts the DC power based on the main power signal and the excess power signal.
1 . A field device for an industrial process comprising:
field device circuitry;
an Ethernet communications in advance physical layer communication circuit (APL communication circuit); and
a power circuit comprising:
a power regulator configured to regulate DC power that powers the field device circuitry and the APL communication circuit;
a main power sensor configured to generate a main power signal that corresponds to the DC power;
a voltage shunt regulator configured to divert excess power to a circuit common; and
an excess power sensor configured to generate an excess power signal that corresponds to a magnitude of the excess power,
wherein the power regulator adjusts the DC power based on the main power signal and the excess power signal.
2 . The field device according to claim 1 , wherein:
the power regulator comprises a variable current source regulator configured to regulate a DC current of the DC power;
the main power sensor comprises a main current sensor configured to generate the main power signal, which corresponds to the DC current;
the excess power comprises an excess current; and
the excess power sensor comprises an excess current sensor configured to generate the excess power signal, which corresponds to a magnitude of the excess current,
wherein the variable current source regulator adjusts the DC current based on the main power signal and the excess power signal.
3 . The field device according to claim 2 , wherein the APL communication circuit comprises:
an analog-to-digital converter configured to convert the excess power signal to a digital value; and
an APL controller configured to generate a reference signal based on the digital value,
wherein the variable current source regulator controls the DC current based on the reference signal.
4 . The field device according to claim 3 , wherein the excess current sensor comprises a sense resistor in series with the excess current, and the excess power signal comprises a voltage.
5 . The field device according to claim 4 , wherein the main current sensor comprises a sense resistor in series with the DC current, and the main power signal comprises a voltage.
6 . The field device according to claim 3 , wherein:
the APL controller is configured to compare the digital value to a threshold value;
the reference signal corresponds to the digital value when the digital value meets a first relationship to the threshold value; and
the reference signal corresponds to a predefined minimum value, which is different from the digital value, when the digital value meets a second relationship to the threshold value.
7 . The field device according to claim 2 , wherein:
the power circuit includes a coupling-decoupling network comprising positive and negative terminals, through which the DC current is received;
the variable current source regulator is connected in series with the positive and negative terminals; and
the field device circuitry and the APL communication circuit are connected in parallel with the positive and negative terminals.
8 . The field device according to claim 2 , wherein the field device circuitry comprises an active component selected from the group consisting of a sensor configured to sense a process parameter and a control device configured to control a process of the industrial process.
9 . The field device according to claim 2 , wherein:
the field device circuitry is powered by a first portion of the DC current;
the APL communication circuit is powered by a second portion of the DC current; and
the excess current corresponds to a difference between the DC current and the sum of the first and second portions of the DC current.
10 . A field device for an industrial process comprising:
a power circuit comprising:
a power regulator configured to regulate a DC power conducted through a positive DC bus;
a main power sensor configured to generate a main power signal that corresponds to the DC power;
a voltage shunt regulator configured to divert excess power from the positive DC bus to a circuit common; and
an excess power sensor configured to generate an excess power signal that corresponds to a magnitude of the excess power;
field device circuitry powered by a first portion of the DC power; and
an Ethernet communications in advance physical layer communication circuit (APL communication circuit) powered by a second portion of the DC power and comprising:
an analog-to-digital converter configured to convert the excess power signal to a digital value; and
an APL controller configured to generate a reference signal based on the digital value,
wherein:
the reference signal corresponds to an excess power value corresponding to the excess power signal when the excess power value meets a first relationship to a threshold value;
the reference signal corresponds to a predefined minimum value, which is different from the excess power value, when the excess power value meets a second relationship to the threshold value; and
the power regulator controls the DC power based on the reference signal and the main power signal.
11 . The field device according to claim 10 , wherein:
the power regulator comprises a variable current source regulator configured to regulate a DC current of the DC power;
the main power sensor comprises a main current sensor configured to generate the main power signal, which corresponds to the DC current;
the excess power comprises an excess current; and
the excess power sensor comprises an excess current sensor configured to generate the excess power signal, which corresponds to a magnitude of the excess current,
wherein:
the reference signal corresponds to an excess current value corresponding to the excess power signal when the excess current value meets a first relationship to a threshold value;
the reference signal corresponds to a predefined minimum value, which is different from the excess current value, when the excess current value meets a second relationship to the threshold value; and
the variable current source regulator controls the DC current based on the reference signal and the main power signal.
12 . The field device according to claim 11 , wherein:
the APL communication circuit comprises an analog-to-digital converter that converts the excess power signal to a digital value corresponding to the excess current value; and
the APL communication circuit generates the reference signal based on a comparison of the digital value to the threshold value.
13 . The field device according to claim 11 , wherein:
the excess current sensor comprises a sense resistor in series with the excess current, and the excess power signal comprises a voltage; and
the main current sensor comprises a sense resistor in series with the DC current, and the main power signal comprises a voltage.
14 . The field device according to claim 11 , wherein the field device circuitry and the APL communication circuit are connected in parallel between the positive DC bus and the circuit common.
15 . The field device according to claim 14 , wherein:
the power circuit includes a coupling-decoupling network comprising positive and negative terminals, through which the DC current is received; and
the variable current source regulator is connected in series with the positive and negative terminals.
16 . The field device according to claim 10 , wherein the field device circuitry comprises an active component selected from the group consisting of a sensor configured to sense a process parameter and a control device configured to control a process of the industrial process.
17 . The field device according to claim 10 , wherein:
the field device circuitry is powered by a first portion of the DC current;
the APL communication circuit is powered by a second portion of the DC current; and
the excess current corresponds to a difference between the DC current and the sum of the first and second portions of the DC current.
18 . A method of managing power in an industrial process field device comprising:
field device circuitry;
an Ethernet communications in advance physical layer communication circuit (APL communication circuit); and
a power circuit comprising:
a power regulator;
a voltage shunt regulator;
a main power sensor; and
an excess power sensor,
the method comprising:
powering the field device circuitry and the APL communication circuit using DC power;
diverting excess power of the DC power to a circuit common using the voltage shunt regulator;
generating a main power signal that corresponds to the DC power using the main power sensor;
generating an excess power signal that corresponds to the excess power using the excess power sensor; and
adjusting the DC power using the power regulator based on the main power signal and a reference corresponding to the excess power signal.
19 . The method according to claim 18 , wherein:
the APL communication circuit comprises:
an analog-to-digital converter; and
an APL controller; and
the method comprises:
converting the excess power signal into a digital value using the analog-to-digital converter;
generating the reference based on the digital value using the APL controller.
20 . The method according to claim 19 , wherein:
generating the reference comprises:
comparing the digital value to a threshold value using the APL controller; and
generating the reference signal based on the comparison;
the reference signal corresponds to the digital value when the digital value meets a first relationship to the threshold value; and
the reference signal corresponds to a predefined minimum value, which is different from the digital value, when the digital value meets a second relationship to the threshold value.