US3611089A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase sensitive motor circuit utilizing real current component
Assignee: Reliance Electric Co
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Filing: 1969-10-06
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Granted: 1971-10-05
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Expires: 1989-10-06
Abstract
Abstract An induction motor energization circuit is disclosed with energization from a variable frequency device such as an inverter. The load current to the induction motor has a considerable lagging power factor and a phase sensitive detector detects only the in-phase or directly out-of-phase component of this load current and applies it as a control to regulate the variable frequency device. At high frequency, the constant volts per cycle operation of the motor is satisfactory but at low speeds the usual energization system of adjusted constant volts per cycle results in overexcitation of the motor causing considerable losses and overheating. By the present invention the use of only the real component of the motor load current as a feedback signal results in considerably lower losses in the motor. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.
Inventors
- 👤 Boris Mokrytzki
- 👤 Peter W Hammond
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:52
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P27/08; H02P23/00; H02P23/03; H02P27/047
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
85 words
A motor circuit comprising, in combination, an induction motor, a variable frequency device connected between voltage source terminals and said motor to supply energy of a variable frequency for varying the speed of said motor, regulator means connected to regulate the output of said variable frequency device, phase sensitive detector means connected to detect only the real component of the motor current, and control means connected to be responsive to the real current component of said detector means and connected to control said regulator means.
Claim 2
Dependent Claim
85 words
A motor circuit comprising, in combination, an induction motor, a variable frequency device connected between voltage source terminals and said motor to supply energy of a variable frequency for varying the speed of said motor, regulator means connected to regulate the output of said variable frequency device, phase sensitive detector means connected to detect only the real component of the motor current, and control means connected to be responsive to the real current component of said detector means and connected to control said regulator means.
Claim 3
Dependent Claim
17 words
A motor circuit as set forth in claim 1, wherein said variable frequency device is an inverter.
Claim 4
Dependent Claim
33 words
A motor circuit as set forth in claim 1, wherein said control means is connected to be responsive to only the in-phase or the 180* out-of-phase component of current of said detector means.
Claim 5
Dependent Claim
32 words
A motor circuit as set forth in claim 1, wherein said phase sensitive detector means includes means to discriminate between the real component and the quadrature phase component of said motor current.
Claim 6
Dependent Claim
33 words
A motor circuit as set forth in claim 1, including a reference signal, and means in said control means to combine said reference signal with said current component to control said regulator means.
Claim 7
Dependent Claim
44 words
A motor circuit as set forth in claim 1, wherein said phase sensitive detector means includes means connected to sense the current to said motor and also includes means to discriminate between the in-phase component and the 180* out-of-phase component of said motor current.
Claim 8
Dependent Claim
38 words
A motor circuit as set forth in claim 6, including a reference signal, and means in said control means to combine said reference signal with either said in-phase or 180* out-of-phase current component to control said regulator means.
Claim 9
Dependent Claim
33 words
A motor circuit as set forth in claim 1, wherein said variable frequency device is connected to supply energy of a variable voltage to said motor for varying the torque of said motor.
Claim 10
Dependent Claim
33 words
A motor circuit as set forth in claim 8, wherein said regulator means is connected to regulate the variable voltage output of said variable frequency device for varying the torque of said motor.
Claim 11
Dependent Claim
37 words
A motor circuit as set forth in claim 8, including means connecting said control means to have an output responsive to said in-phase component of current and regulating the variable voltage output of said variable frequency device.
Claim 12
Dependent Claim
54 words
A motor circuit as set forth in claim 1, including an IR drop compensation reference source, a multiplier, means to supply said reference source and said real current component to two inputs of said multiplier, and means connecting the output of said multiplier to control said regulator means as an IR drop compensation signal.
Claim 13
Dependent Claim
51 words
A motor circuit as set forth in claim 11, including means to sense the difference between motoring current and regenerative current in said motor, and means to add or subtract, respectively, said IR drop compensation signal to said regulator according to whether motoring or regenerative current is flowing in said motor.
Claim 14
Dependent Claim
122 words
A motor circuit as set forth in claim 1, wherein said phase sensitive detector means includes first and second circuit paths connected in parallel, resistors in said first and second paths to establish the current flow in said first path at one-half the current flow in said second path, a unity gain inverting amplifier in said second path to establish a negative current therein, switch means connected in said second path, means connected to cause conduction through said switch means of current proportioNal to motor current in synchronism with the voltage polarity reversals of said variable frequency device, whereby at the output of said two paralleled paths a current is produced which is proportional to only the in-phase or 180* out-of-phase current.
Claim 15
Dependent Claim
187 words
A motor circuit as set forth in claim 1, wherein said motor is a three-phase motor and said variable frequency device is a three-phase supply, said phase sensitive detector means including a detector circuit for each phase, each detector circuit including first and second circuit paths connected in parallel, an input to each detector circuit from the respective phase current terminal of said variable frequency device, resistors in said first and second paths to establish the current flow in said first path at one-half the current flow in said second path, a unity gain inverting operational amplifier in said second path to establish a negative current therein, a semiconductor switch connected in said second path, ring counter means connected to trigger said semiconductor switch into conduction in synchronism with the polarity of the voltage of the respective phase becoming positive, an inverting summing amplifier having an input and an output, and means to connect the outputs of all three detector circuits to the input of said summing amplifier and the output thereof being an IR drop compensation signal proportional to only the in-phase or 180* out-of-phase current.
Claim 16
Dependent Claim
155 words
A motor circuit as set forth in claim 1, wherein said variable frequency device is an inverter connected to supply energy of a variable frequency for variable speed and a variable voltage for variable torque of said motor, voltage control means in said regulator means connected to control the variable frequency of said inverter output, means connected to sense the current in said motor connected to said phase sensitive detector means to have same discriminate between in-phase and quadrature phase current; and said control means including an IR drop compensation reference source, a multiplier, means connecting said IR drop compensation reference source to said multiplier, means connecting the in-phase current output of said phase sensitive detector to said multiplier, and said multiplier multiplying the two inputs and having an output as an error signal connected to said voltage control means for IR drop compensation in accordance with the in-phase component of current in said motor.
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) | 1974-10-04 | 1975-04-05 | 1975-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-04 | 1979-04-05 | 1979-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-04 | 1983-04-05 | 1983-10-05 | $7700.00 | Window Closed / Lapsed |