Digital line protection with supply voltage drop safety

Patent metadata

Field	Value
Publication number	US-10554039-B2
Application number	US-201715675107-A
Country	US
Kind code	B2
Filing date	Aug 11, 2017
Priority date	Aug 11, 2017
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

A line protection device includes a current sensor, a digital filter circuit, a switch control circuit, and a non-volatile memory circuit. The current sensor is adapted to a sense a value of electric current through the electric line. The digital filter circuit is adapted to perform digital filtering of the value of electric current. The switch control circuit is adapted to control a switch to interrupt flow of the electric current through the electric line depending on the digitally filtered value of the electric current. The non-volatile memory circuit is adapted to store a state of the digital filter circuit.

First claim

What is claimed is:

1. A line protection device comprising:
a current sensor adapted to a sense a value of an electric current through an electric line;
a digital filter circuit adapted to perform digital filtering of the value of electric current, wherein the digital filter circuit comprises at least one delay element;
a switch control circuit adapted to control a switch to interrupt flow of the electric current through the electric line depending on the digitally filtered value of the electric current; and
a non-volatile memory circuit adapted to store a state of the digital filter circuit, wherein the non-volatile memory circuit is adapted to store a state of the at least one delay element.

2. The line protection device according to claim 1 , wherein the non-volatile memory circuit comprises at least one capacitor adapted to capacitively store the state of the digital filter circuit.

3. The line protection device according to claim 1 ,
wherein the at least one delay element includes a first register and a second register,
wherein the at least one delay element is adapted to sequentially store input values of the at least one delay element in the first register and then in the second register, and
wherein the non-volatile memory circuit is adapted to store a state of the first register and a state of the second register.

4. The line protection device according to claim 3 ,
wherein the at least one delay element further comprises an encoder adapted to calculate a corresponding error detection code for each of the input values,
wherein the at least one delay element is adapted to store the input values each with the corresponding error detection code in the first register, and
wherein the at least one delay element comprises a selector adapted to select, depending on the stored error detection code, the input value stored in one of the first register and the second register as an output value of the at least one delay element.

5. The line protection device according to claim 4 , wherein the selector is adapted to:
select the input value stored in the first register as an output value of the at least one delay element if the error detection code indicates that the input value is error free; and
select the input value stored in the second register as an output value of the at least one delay element if the error detection code indicates that the input value stored in the first register is erroneous.

6. The line protection device according to claim 1 , wherein the non-volatile memory circuit comprises a logic circuit adapted to block an input signal of the non-volatile memory circuit response to a signal indicating that a supply voltage of the line protection device is below a threshold.

7. The line protection device according to claim 1 , wherein said digital filtering comprises calculating a polynomial function of the value of the electric current and low-pass filtering of the calculated polynomial function.

8. The line protection device according to claim 1 , wherein the switch control circuit is adapted to control the switch depending on a comparison of the digitally filtered value of the electric current to a first threshold.

9. The line protection device according to claim 1 , wherein the switch control circuit is adapted to control the switch depending on a comparison of the value of the electric current to a second threshold.

10. The line protection device according to claim 1 , wherein the line protection device comprises the switch.

11. A method of line protection, the method comprising:
sensing a value of an electric current through an electric line;
digital filtering of the value of electric current by a digital filter circuit;
controlling a switch to interrupt flow of the electric current through the electric line depending on the digitally filtered value of the electric current; and
storing a state of the digital filter circuit by a non-volatile memory circuit by storing a state of at least one delay element of the digital filter circuit by the non-volatile memory circuit.

12. The method according to claim 11 , further comprising capacitively storing the state of the digital filter circuit by the non-volatile memory circuit.

13. The method according to claim 11 , further comprising:
storing input values of the at least one delay element of the digital filter circuit sequentially in a first register of the at least one delay element and then in a second register of the at least one delay element; and
storing a state of the first register and a state of the second register by the non-volatile memory circuit.

14. The method according to claim 13 , further comprising:
calculating a corresponding error detection code for each of the input values,
storing the input values each with the corresponding error detection code in the first register, and
depending on the stored error detection code, selecting the input value stored in one of the first register and the second register as an output value of the at least one delay element.

15. The method according to claim 14 , further comprising:
selecting the input value stored in the first register as an output value of the at least one delay element if the error detection code indicates that the input value stored in the first register is error free; and
selecting the input value stored in the second register as an output value of the at least one delay element if the error detection code indicates that the input value stored in the first register is erroneous.

16. The method according to claim 11 , further comprising blocking an input signal of the non-volatile memory circuit in response to a signal indicating that a supply voltage of the line protection device is below a threshold.

17. The method according to claim 11 , wherein the digital filtering comprises calculating a polynomial function of the value of the electric current and low-pass filtering of the calculated polynomial function.

18. The method according to claim 11 , further comprising controlling the switch depending on a comparison of the digitally filtered value of the electric current to a first threshold.

19. The method according to claim 11 , further comprising controlling the switch depending on a comparison of the value of the electric current to a second threshold.

20. A line protection device comprising:
a current sensor adapted to a sense a value of an electric current through an electric line;
a digital filter circuit adapted to perform digital filtering of the value of electric current;
a switch control circuit adapted to control a switch to interrupt flow of the electric current through the electric line depending on the digitally filtered value of the electric current; and
a non-volatile memory circuit adapted to store a state of the digital filter circuit, wherein the non-volatile memory circuit comprises a logic circuit adapted to block an input signal of the non-volatile memory circuit response to a signal indicating that a supply voltage of the line protection device is below a threshold.

21. The line protection device of claim 20 , wherein the non-volatile memory circuit comprises at least one capacitor adapted to capacitively store the state of the digital filter circuit.

Assignees

• Infineon Technologies Ag

Inventors

• Asam Michael

Classifications

• H02H7/263 Primary

  involving transmissions of measured values (comparison of currents or voltages using pilot wires H02H3/30) · CPC title

• G01R31/58

  Testing of lines, cables or conductors (testing of electric windings G01R31/72) · CPC title

• H02H3/08 Primary

  responsive to excess current (responsive to abnormal temperature caused by excess current H02H5/04) · CPC title

• G01R31/085

  in power transmission or distribution lines, e.g. overhead · CPC title

• G01R19/16571

  comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current (G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533, G01R19/1659 take precedence; measuring currents by using elements sensitive to the magnetic field generated G01R15/14; measuring earth resistance G01R27/18; testing for leakage or short circuits in electrical apparatus G01R31/52) · CPC title