US4516008A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for calculating the root mean square (RMS) current in a resistance welding system
Assignee: PERC ACQUISITION CORP A CORP OF CA
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Filing: 1983-03-14
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Granted: 1985-05-07
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Expires: 2003-03-14
Abstract
Abstract A system is provided for use in a microprocessor controlled controller for a resistance welding machine for calculating the RMS value of the welding current so as to provide a closed loop control of the RMS current in order to eliminate the effect of variations in load and line voltage on the welding current and to provide a constant welding tip temperature in the presence of such variations.
Inventors
- 👤 Gary A. Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:13
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; B; B23; B23K; B23K11/00; B23K11/24; B23K11/25; B23K11/252; G01; G01R; G01R19/00; G01R19/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
214 words
A system for caluculating the RMS value of a sinusoidal current flowing in an inductive/resistance welding system, or the like, comprising: an input circuit for receiving a sinusoidal current I(t); a full-wave rectifier circuit connected to said input circuit for providing a current representing the absolute value of the sinusoidal current |I(t)|; an integrating circuit connected to said full-wave rectifier circuit for deriving a signal I N representative of the integral ∫I(t)dt of the output of the full-wave rectifier circuit; circuitry including a threshold detector circuit connected to said full-wave rectifier circuit for producing a signal representing the conduction angle γ of the sinusoidal current; and a microprocessor means including a look-up table stored in its memory, said microprocessor means being connected to the integrating circuit and to said last-named circuitry and being responsive to the outputs I N and γ of the integrating circuit and last-named circuitry for producing a signal derived from said look-up table representing the ratio of two signals I RN /I N , and said microprocessor means including means for performing a multiplication function for multiplying the output I N of said integrating circuit and the output I RN /I N of said look-up table to obtain a signal I RN representing the RMS value of the sinusoidal current.
Claim 2
Independent Claim
214 words
A system for caluculating the RMS value of a sinusoidal current flowing in an inductive/resistance welding system, or the like, comprising: an input circuit for receiving a sinusoidal current I(t); a full-wave rectifier circuit connected to said input circuit for providing a current representing the absolute value of the sinusoidal current |I(t)|; an integrating circuit connected to said full-wave rectifier circuit for deriving a signal I N representative of the integral ∫I(t)dt of the output of the full-wave rectifier circuit; circuitry including a threshold detector circuit connected to said full-wave rectifier circuit for producing a signal representing the conduction angle γ of the sinusoidal current; and a microprocessor means including a look-up table stored in its memory, said microprocessor means being connected to the integrating circuit and to said last-named circuitry and being responsive to the outputs I N and γ of the integrating circuit and last-named circuitry for producing a signal derived from said look-up table representing the ratio of two signals I RN /I N , and said microprocessor means including means for performing a multiplication function for multiplying the output I N of said integrating circuit and the output I RN /I N of said look-up table to obtain a signal I RN representing the RMS value of the sinusoidal current.
Claim 3
Dependent Claim
48 words
The system defined in claim 1, in which said integrating circuit includes circuit means for converting the current from said full-wave rectifier circuit into frequency modulated pulses, and further circuit means for counting the frequency modulated pulses during each half-cycle of the current from said full-wave rectifier circuit.
Claim 4
Dependent Claim
21 words
The system defined in claim 1, in which said RMS value is calculated in the presence of a non-capacitive inductive/resistance load.
Claim 5
Dependent Claim
19 words
The system defined in claim 1, in which said full-wave rectifier is formed of a pair of operational amplifiers.
Claim 6
Dependent Claim
15 words
The system defined in claim 1, in which said threshold detector includes an operational amplifier.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-05-06 | 1988-11-05 | 1989-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-06 | 1992-11-05 | 1993-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-06 | 1996-11-05 | 1997-05-07 | $7700.00 | Window Closed / Lapsed |