US4620157A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reactive power to DC signal converter
Assignee: Yokogawa Electric Corp
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Filing: 1985-06-06
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Granted: 1986-10-28
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Expires: 2005-06-06
Abstract
Abstract The output from a capacitor, which shifts a voltage output by π/2, and a detected frequency output, are multiplied by a pulse width modulation circuit, and a current input is switched by the multiplied output to convert a reactive power to a corresponding DC signal. The converter has improved frequency characteristics.
Inventors
- 👤 Eiji Hayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:37
CPC Classifications
G; G01; G01R; G01R21/00; G01R21/001; G01R21/003
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
99 words
A reactive power to DC signal converter comprising a capacitor for shifting the phase of either a voltage input or a current input to an AC circuit; a frequency detector circuit for producing a signal proportional to a frequency in the AC circuit; a first multiplier circuit for multiplying the output from said capacitor by the output from said frequency detector circuit; a second multiplier circuit for multiplying the voltage input or the current input to the AC circuit by the output from said first multiplier circuits; and a smoothing circuit for smoothing the output from said second multiplier.
Claim 2
Dependent Claim
99 words
A reactive power to DC signal converter comprising a capacitor for shifting the phase of either a voltage input or a current input to an AC circuit; a frequency detector circuit for producing a signal proportional to a frequency in the AC circuit; a first multiplier circuit for multiplying the output from said capacitor by the output from said frequency detector circuit; a second multiplier circuit for multiplying the voltage input or the current input to the AC circuit by the output from said first multiplier circuits; and a smoothing circuit for smoothing the output from said second multiplier.
Claim 3
Dependent Claim
115 words
The converter of claim 1, wherein said frequency detector circuit comprises a frequency detector and a reciprocal generating circuit for generating a signal inversely proportional to the output from said frequency detector, said first multiplier circuit comprises a pulse width modulation circuit comprising an integrator and a voltage comparator having a hysteresis for comparing the output from said integrator with a voltage of a prescribed level, and means for applying the output from said voltage comparator, the output from said capacitor, and the output from said frequency detector circuit to said integrator for producing a pulse width modulation signal corresponding to the amplitude of the voltage input or the current input to the AC circuit.
Claim 4
Dependent Claim
38 words
The converter of claim 2, wherein said voltage comparator comprises first and second inverters connected in series to an input resistor, and a resistor for feeding the output from said second inverter therethrough back to said first inverter.
Claim 5
Dependent Claim
41 words
The converter of claim 2, wherein said voltage comparator comprises first and second NAND gates connected in series to an input resistor, and a resistor for feeding the output from said second NAND gate therethrough back to said first NAND gate.
Claim 6
Dependent Claim
23 words
The converter of claim 2, wherein said frequency detector circuit comprises an operational amplifier and a zener diode connected across said operational amplifier.
Claim 7
Dependent Claim
33 words
The converter of claim 2, wherein said reciprocal generating circuit comprises a transistor driven by the output from said frequency detector and a unidirectional integrator connected to an output terminal of said transistor.
Claim 8
Dependent Claim
40 words
The converter of claim 1, wherein said first and second multiplier circuits are provided for each of a plurality of phases and wherein said frequency detector circuit and said smoothing circuit are shared in common by said plurality of phases.
Claim 9
Dependent Claim
29 words
The converter of claim 7, wherein each of said first multiplier circuits comprises a pulse width modulation circuit, and each of said second multiplier circuits comprises a switch element.
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) | 1989-10-27 | 1990-04-28 | 1990-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-27 | 1994-04-28 | 1994-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-27 | 1998-04-28 | 1998-10-28 | $7700.00 | Window Closed / Lapsed |