PULSE SAMPLING RESISTANCE METERING METHOD AND MEANS

• US 3,731,189 A
• Filed: 05/18/1972
• Issued: 05/01/1973
• Est. Priority Date: 05/15/1970
• Status: Expired due to Term

• Current Assignee: Sanwa Business Credit Corporation
• Original Assignee: Harold M. Sharaf, Richard L. Eby
• Inventors: Sharaf, Harold M., Eby, Richard L.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US05/254,497
• Time in Patent Office: 348 Days
• Field of Search: 324/62,29.5,133 320/21,29,32,39,43,48
• US Class Current: 324/710
• CPC Class Codes: G01R 27/02 Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant by measuring phase angle only G01R25/00
• CPC Class Codes: G01R 27/205 Measuring contact resistance of connections, e.g. of earth connections
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

A continuously operating low dissipation system for sensing the electrical resistance of an element while the element carries a normal operating current. A pulse of electrical energy having a regulated first parameter is switched through the element while a second parameter of the element'"'"''"'"'s response to the energy pulse is simultaneously measured. These two known parameters provide the information necessary to determine the element'"'"''"'"'s resistance using Ohm'"'"''"'"'s law. The system is calibrated for the regulated level of the first parameter while the second parameter is amplified and stored in a sampling circuit for continuous display between pulses as an indication of resistance. The pulse techniques of this disclosure allow continuous operation of the system without heating of the resistive element or excessive power use. The resistance indication is additionally useful for indicating the remaining charge in a battery where the indicated resistance is the battery'"'"''"'"'s internal resistance. A distinct battery terminal voltage is also given.

Claims

1. A low dissipation system for detecting the electrical resistance of an element while said element is in normal operation in an electrical circuit comprising:

a. means for switching through said element a pulse of electrical energy with a regulated first parameter, said pulse of electrical energy defining a pulse state separating adjacent ambient states;

b. means for sensing a second parameter characteristic of the Ohm'"'"''"'"'s law response of said element to the first parameter of said pulse of electrical energy passing through said element, said second parameter being representative of said element'"'"''"'"'s resistance; and

, c. sample and hold means for sampling and then holding during the ambient state between pulse states a signal representative of the second parameter response of said element as sensed by said sensing means during a preceding pulse state.

2. The system of claim 1 further comprising output means for converting the signal held by said sample and hold means to information representative of said element'"'"''"'"'s resistance.

3. The system of claim 1 further characterized by being continuously operable with a sequence of pulses of electrical energy.

4. The system of claim 1 characterized by said means for sensing including means for amplifying said second parameter.

5. The system of claim 1 further characterized by said ambient state having ambient electrical energy passing through said element which ambient energy continues during said pulse state.

6. The system of claim 5 characterized by having means for eliminating the effects of said ambient energy in said second parameter.

7. The system of claim 1 further characterized by said pulse of electrical energy being of a power level able to generate substantial heat in said element and said system if continuously applied, said pulse of energy being applied in pulses of short duration relative to the time between pulses in order to produce little total heating effect.

8. The system of claim 1 further including a set of sense leads conducting the second parameter characteristic of the response of said element during the pulse state to said sensing means substantially without signal loss in said sense leads.

9. The system of claim 1 further including means for indicating whether said first parameter is maintained at said preset level during said pulse state.

10. A low dissipation system for detecting the electrical resistance of an element while said element is in normal operation in an electrical circuit comprising:

a. source means for supplying electrical energy;

b. means for generating a pulse signal defining a pulse state separating adjacent ambient states, said pulse state being of a duration short with respect to said ambient state;

c. means for conducting through said element electrical energy with a regulated first parameter from said source means during each said pulse state in response to said pulse signal;

d. means for sensing a second parameter characteristic of the Ohm'"'"''"'"'s law response of said element to the first parameter of said pulse of electrical energy passing through said element, said second parameter being representative of said element'"'"''"'"'s resistance; and

, e. means for indicating a quantity represeNtative of the second parameter response of said element as sensed by said sensing means during preceding pulse states.

11. The system of claim 10 characterized by said conducting means further comprising:

a. means for monitoring said first parameter during said pulse state; and

b. means for controlling the pulse of electrical energy passed through said element by said conducting means during said pulse state to achieve regulation of said first parameter, as monitored, to a preset level.

12. The system of claim 11 characterized:

a. by said ambient state having ambient electrical energy passing through said element, said ambient energy continuing during said pulse state; and

, b. by having means for eliminating the effect of said ambient energy in said first and second parameters.

13. The system of claim 12 further including:

a. a first set of sense leads conducting the first parameter characteristic of the response of said element during the pulse state to said monitoring means substantially without signal loss; and

, b. a second set of sense leads conducting the second parameter characteristic of the response of said element during the pulse state to said sensing means substantially without signal loss in said sense leads.

14. The system of claim 13 characterized by said means for sensing including means for amplifying said second parameter as sensed.

15. The system of claim 11 further including:

a. a first set of sense leads conducting the first parameter characteristic of the response of said element during the pulse state to said monitoring means substantially without signal loss; and

b. a second set of sense leads conducting the second parameter characteristic of the response of said element during the pulse state to said sensing means substantially without signal loss in said sense leads.

16. The system of claim 11 further comprising:

a. means for indicating whether the first parameter is maintained at said preset level during said pulse state; and

, b. means within said generating means for producing a pulse signal that has a rectangular shape.

17. A method of measuring small resistance in an element without generating extreme heat and of enabling measurement of said resistance while said element is in use passing ambient electrical energy comprising the steps of:

a. pulsing a pulse of electrical energy having a regulated first parameter through said element periodically, said pulse of electrical energy having a power magnitude that would generate substantial heating if continuously applied but of slight heating effect when applied as a periodic pulse of short duration relative to the interval between pulses;

b. sensing a second parameter characteristic of the Ohm'"'"''"'"'s law response of said element to said pulse of energy to generate a signal whose level is representative of the second parameter; and

, c. sampling and holding during the interval between pulses, the level of said signal during a preceding pulse state.

18. The method of claim 17 further comprising the step of converting the sampled and held level of said signal to an indication of said element'"'"''"'"'s resistance.