Architecture and method to determine leakage impedance and leakage voltage node

• US 9,523,730 B2
• Filed: 01/31/2013
• Issued: 12/20/2016
• Est. Priority Date: 04/08/2009
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Streit, Lawrence C.
• Primary Examiner(s): Tang, Minh N
• Application Number:
  US13/756,101
• Publication Number:
  US 20130151175A1
• Time in Patent Office: 1,419 Days
• US Class Current: 1/1
• CPC Class Codes: G01R 19/2509 Details concerning sampling, digitizing or waveform capturing
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00

Abstract

A circuit, system, machine-readable storage medium and method for detecting the leakage impedance in a voltage source is described. The method for identifying a presence of a leakage path in a multi-cell floating voltage source may include supplying a current to a node of the floating voltage source and sampling the voltage of the floating voltage source using a pair of amplifiers connecting in inverting configurations. The method may include sampling a reference ground potential using a reference amplifier connected in an inverting configuration. Each of the amplifiers may output an output signal. The method may include adjusting the current supplied to the node of the floating voltage source and resampling the voltage of the floating voltage source and the reference ground potential. The value of the leakage impedance may be calculated using the sampled and resampled values. The measurements may be performed independent of the battery voltage.

Claims

1. A method for identifying a presence of a leakage path in a floating voltage source, comprising:

supplying a current to a node of the floating voltage source;

sampling the voltage of the floating voltage source using a pair of amplifiers connecting in inverting configurations, wherein each of the pair of amplifiers outputs an output signal;

sampling a reference ground potential using a reference amplifier connected in an inverting configuration, wherein the reference amplifier outputs a reference output signal;

adjusting the current supplied to the node of the floating voltage source;

resampling the voltage of the floating voltage source and the reference ground potential; and

calculating a value of a leakage impedance using the sampled and resampled values.

2. The method of claim 1, further comprising comparing the calculated value of the leakage impedance with a threshold value.

3. The method of claim 2, further comprising generating a notification when the threshold value is exceeded.

4. The method of claim 2, wherein comparing further comprises accessing a memory to retrieve a stored threshold value.

5. The method of claim 1, further comprising storing the sampled and resampled outputs and reference outputs in a memory.

6. The method of claim 1, wherein supplying further comprises generating the current as a function of one or more outputs of the pair of amplifiers and the reference amplifier.

7. The method of claim 1, wherein sampling comprises sampling the outputs of the pair of amplifiers and the reference amplifier sequentially.

8. The method of claim 1, wherein sampling comprises sampling the outputs of the pair of amplifiers and the reference amplifier simultaneously.

9. A system for determining a leakage impedance of a floating voltage source, comprising:

a detection circuit comprising;

a first amplifier and a second amplifier, a first input of the first amplifier coupled to a first terminal of the floating voltage source and a first input of the second amplifier coupled to a second terminal of the floating voltage source, a second input of each of the first and second amplifiers coupled to a reference voltage; and

a third amplifier, a first input of the third amplifier coupled to a reference ground potential and a second input of the third amplifier coupled to the reference voltage;

a processor for processing outputs of the first, second and third amplifiers to determine the leakage impedance; and

a current source coupled to the floating voltage source.

10. The system of claim 9, wherein a current supplied by the current source is a function of at least one output of the first, second and third amplifiers.

11. The system of claim 9, further comprising;

a first switch disposed between the first input of the first amplifier and the first terminal of the floating voltage source;

a second switch disposed between the first input of the second amplifier and the second terminal of the floating voltage source; and

a third switch disposed between a first input of the third amplifier and the reference ground potential,

wherein at least one of the switches forms an isolation barrier between the floating voltage source and the outputs of the first, second and third amplifiers.

12. The system of claim 9, further comprising:

an isolated power source providing power to the first, second and third amplifiers.

13. The system of claim 9, further comprises:

an analog-to-digital converter coupled to the outputs of the first, second and third amplifiers, wherein the analog-to-digital converter provides the processor with digital signals corresponding to the outputs of the first, second and third amplifiers.

14. The system of claim 9, wherein the first, second and third amplifiers are connected in an inverting configuration.

15. A circuit, comprising:

a first amplifier having an inverting input coupled to a first terminal of a floating voltage source, a non-inverting input coupled to a first reference potential, and an output coupled to a first output of the circuit;

a second amplifier having an inverting input coupled to a second terminal of the floating voltage source, a non-inverting input coupled to the first reference potential, and an output coupled to a second output of the circuit;

a third amplifier having an inverting input coupled to a second reference potential, a non-inverting input coupled to the first reference potential, and an output coupled to a third output of the circuit;

a current source coupled to at least one of the first terminal and the second terminal of the floating voltage source;

a first switch disposed between the inverting input of the first amplifier and the first terminal of the floating voltage source;

a second switch disposed between the inverting input of the second amplifier and the second terminal of the floating voltage source; and

a third switch disposed between the inverting input of the third amplifier and the second reference potential.

16. The circuit of claim 15, wherein the current source provides a current that is a function of at least one of the outputs of the first, second and third amplifiers.

17. The circuit of claim 15, further comprising one or more analog-to-digital converters to simultaneously sample the first, second and third outputs.

18. The circuit of claim 15, further comprising a multiplexer and an analog-to-digital converter to sequentially sample the first, second and third outputs.

19. The circuit of claim 15, further comprising a processor to detect a leakage impedance of the floating voltage source based on the first, second and third outputs.

20. The circuit of claim 15, further comprising a processor for diagnosing operation of the circuit based on the first, second and third outputs.

21. The circuit of claim 20, wherein diagnosing comprises determining if the circuit is settled.

22. A method for identifying leakage impedance of a floating voltage source coupled to a detection circuit, the method comprising:

sampling voltages of the floating voltage source during a first state of the detection circuit using a pair of amplifiers connected in inverting configurations;

sampling voltages of the floating voltage source during a second state of the detection circuit using the pair of amplifiers;

sampling a reference ground potential during the first state of the detection circuit using a reference amplifier connected in an inverting configuration;

sampling a reference ground potential during the second state of the detection circuit using the reference amplifier;

calculating a value of a leakage impedance using the sampled voltages and the sampled reference ground potentials for the first state of the detection circuit and the second state of the detection circuit, and

providing a current from a current source having a first value to a node of the floating voltage source to set the first state of the detection circuit and providing the current having a second value to the node of the floating voltage source to set the second state of the detection circuit.

23. The method of claim 22, wherein providing the current further comprises setting at least one of the first and second values of the current provided by the current source as a function of one or more of the amplifier outputs.

24. The method of claim 22, wherein calculating further comprises calculating the value of the leakage impedance independently of the current source and the floating voltage source.

25. A method for performing measurements using a detection circuit coupled to a floating voltage source, the method comprising:

providing a first current to one of a first terminal and a second terminal of the floating voltage source to set a first operational state of the detection circuit;

sampling an output of a first amplifier of the detection circuit to obtain a sampled output of the first amplifier for the first operational state of the detection circuit, the first amplifier coupled to the first terminal of the floating voltage source in an inverting configuration;

sampling an output of a second amplifier of the detection circuit to obtain a sampled output of the second amplifier for the first operational state of the detection circuit, the second amplifier coupled to the second terminal of the floating voltage source in an inverting configuration;

sampling an output of a third amplifier of the detection circuit to obtain a sampled output of the third amplifier for the first operational state of the detection circuit, the third amplifier coupled to a reference ground potential in an inverting configuration;

providing a second current to one of the first terminal and the second terminal of the floating voltage source to set a second operational state of the detection circuit;

resampling the outputs of the first, second and third amplifiers for the second operational state of the detection circuit; and

calculating a value of a leakage impedance of the floating voltage source based on the sampled and resampled outputs of the first, second and third amplifiers.

26. The method of claim 25, wherein sampling further comprises sampling the outputs of the first and second amplifiers sequentially.

27. The method of claim 25, wherein sampling further comprises sampling the outputs of the first and second amplifiers simultaneously.

28. The method of claim 25, wherein providing the first and second currents further comprises setting at least one of the first and second currents as a function of one or more outputs of the first, second and third amplifiers.

29. The method of claim 28, further comprising diagnosing operation of the detection circuit based on the outputs of the first, second and third amplifiers for at least one of the first and second operational states of the detection circuit.

30. The method of claim 29, wherein diagnosing further comprises comparing the outputs of the first, second and third amplifiers.

31. The method of claim 30, wherein comparing further comprises determining whether one or more of the outputs of the first, second and third amplifiers are settled.

32. The method of claim 31, further comprising resampling at least one of the outputs of the first, second and third amplifiers for at least one of the first and second operational states of the detection circuit if it is determined that at least one of the outputs of the first, second and third amplifiers is not settled.

33. method of claim 29, wherein calculating the value of the leakage impedance further comprises calculating a first component and a second component of the leakage impendence, the first and second components further based on gains of the first, second and third amplifiers.