US3787723A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vehicular drive system with electric assist
Assignee: Deere and Co
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Filing: 1970-03-02
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Granted: 1974-01-22
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Expires: 1990-03-02
Abstract
Abstract A vehicle is equipped with a main drive system and an electric assist drive system which is actuated by the operator when the vehicle speed falls below some predetermined speed. A prime mover for the vehicle, in addition to driving two wheels directly through a primary transmission, drives a three-phase electrical alternator. The alternator energizes an induction motor with a torque-regulating control system for independently driving two other wheels of the vehicle to provide greater traction at low speeds. The rotor circuit of the induction motor includes a rectifier bridge which feeds a line-commutated inverter for coupling the slip power back to the stator input. The control system determines the firing angle for conduction of the switches in the inverter to control the output torque of the induction motor as a function of speed. The system includes a shaping network which defines the desired speed-torque characteristic for accelerating the vehicle; and it generates a signal representative of a demand torque for a given motor speed. Another circuit sensing rotor current generates a signal representative of the load torque. A comparison circuit receives the two signals representative respectively of the actual torque and the desired torque for that speed; and it generates an error signal for controlling the firing angle of the switches in the inverter circuit such that the motor and vehicle are accelerated along the torque-speed envelope of the shaping network once the assisting system is actuated. Thus, the control system regulates the output torque of the assisting induction motor as a predetermined function of vehicle speed.
Inventors
- 👤 L Magnuson
- 👤 A Kusko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:08
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P23/00; H02P23/08; H02P25/00; H02P25/16; H02P25/24; H02P25/26; H02P21/00; H02P21/06; H02P21/08; H02P21/09; H02P2201/00; H02P2201/13
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
81 words
A method of regulating the output torque of an induction motor with a line-commutated inverter in its rotor circuit comprising: generating a first signal representative of motor speed; generating from said motor speed signal a second signal representative of a desired output torque for that speed; generating a third signal representative of the actual motor torque; and controlling the conduction angle of the inverter switches such that said actual torque signal approaches said desired torque signal over a predetermined operating range.
Claim 2
Independent Claim
81 words
A method of regulating the output torque of an induction motor with a line-commutated inverter in its rotor circuit comprising: generating a first signal representative of motor speed; generating from said motor speed signal a second signal representative of a desired output torque for that speed; generating a third signal representative of the actual motor torque; and controlling the conduction angle of the inverter switches such that said actual torque signal approaches said desired torque signal over a predetermined operating range.
Claim 3
Dependent Claim
44 words
The method of claim 1 wherein said second-named step comprises: storing in a circuit a desired speed-torque envelope; and driving said circuit with said signal representative of motor speed thereby generating from said circuit a signal representative of a desired torque for that speed.
Claim 4
Dependent Claim
53 words
The method of claim 2 wherein said step of controlling said conduction angle of the inverter switches includes comparing said desired torque signal with said actual torque signal; advancing said conduction angle when said desired torque signal is the greater; and retarding said conduction angle when said desired torque signal is the lesser.
Claim 5
Independent Claim
93 words
A system for controlling the torque of an induction motor having a stator and a rotor comprising: inverter means energized by rotor current including controllable switching means for coupling rotor power back to said stator; generator means sensing rotor speed for generating a signal representative of a desired motor torque for the sensed speed; and circuit means receiving the signal of said generator means for controlling the conduction of said inverter switching means in response to said desired torque signal thereby to regulate rotor current so that said motor produces a predetermined torque.
Claim 6
Independent Claim
93 words
A system for controlling the torque of an induction motor having a stator and a rotor comprising: inverter means energized by rotor current including controllable switching means for coupling rotor power back to said stator; generator means sensing rotor speed for generating a signal representative of a desired motor torque for the sensed speed; and circuit means receiving the signal of said generator means for controlling the conduction of said inverter switching means in response to said desired torque signal thereby to regulate rotor current so that said motor produces a predetermined torque.
Claim 7
Dependent Claim
37 words
The system of claim 4 wherein said generator means includes circuit means for generating said desired torque as a decreasing function of motor speed over at least a portion of the desired speed-torque characteristic for said system.
Claim 8
Dependent Claim
44 words
The system of claim 5 wherein said generator means comprises: sensor means sensing motor speed for generating a signal representative thereof; and torque signal generator means receiving said sensor signal for generating a signal representative of a desired system torque for that sensor signal.
Claim 9
Dependent Claim
54 words
The system of claim 6 wherein said torque signal generator means includes a torque lImiting circuit for generating a constant output signal when said sensor signal indicates a speed below a predetermined speed, and an output signal decreasing from said constant signal when said sensor signal indicates a speed above said predetermined constant speed.
Claim 10
Dependent Claim
42 words
The system of claim 7 further comprising first circuit means for setting the level of said desired torque signal which is constant with speed, and second circuit means for independently setting the slope of said desired torque signal which decreases with speed.
Claim 11
Dependent Claim
87 words
The system of claim 4 wherein said last-named circuit means includes torque sensor means for generating a signal representative of actual motor torque; comparison means receiving said signal representative of desired torque and said signal representative of actual torque for generating an error signal; and trigger circuit means actuating said switching means of said inverter in response to said error signal to cause said actual torque signal to approach said desired torque signal whereby the torque of said motor is regulated as a function of its speed.
Claim 12
Dependent Claim
71 words
In a system for controlling an induction motor with a line-commutated inverter, the method of limiting the output torque thereof comprising: sensing motor speed; generating a desired torque signal representative of a predetermined torque limit for that speed; generating a torque signal representative of actual motor torque; and retarding the conduction angle of the switches in said inverter when said comparison indicates said actual torque is greater than said desired torque.
Claim 13
Dependent Claim
71 words
In a system for controlling an induction motor with a line-commutated inverter, the method of limiting the output torque thereof comprising: sensing motor speed; generating a desired torque signal representative of a predetermined torque limit for that speed; generating a torque signal representative of actual motor torque; and retarding the conduction angle of the switches in said inverter when said comparison indicates said actual torque is greater than said desired torque.
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) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |