Electricity: motive power systems – Induction motor systems – Primary circuit control
Reexamination Certificate
2000-12-12
2001-09-18
Riley, Shawn (Department: 2838)
Electricity: motive power systems
Induction motor systems
Primary circuit control
Reexamination Certificate
active
06291963
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to control of a polyphase alternating-current motor/generator during mal-functions in a circuit component of an inverter or when a coil becomes disconnected.
BACKGROUND OF THE INVENTION
Tokkai Hei 11-275826 published by the Japanese Patent Office in 1999 discloses a motor/generator which drives a plurality of rotors independently by applying a polyphase alternating current to stator coils. The invention disclosed in Tokkai Hei 11-275826 forms a part of the invention that has been filed at the USPTO as U.S. patent application Ser. No. 09/275,785 on Mar. 25, 1999 before the priority date of this invention and was granted as U.S. Pat. No. 6,049,152 after the priority date of this invention.
Tokkai Hei 6-311783 published by the Japanese Patent Office in 1994 discloses a motor/generator provided with two groups of coil units each comprising three coils connected by a star connection and supplied with a three-phase alternating current. A control circuit detects neutral electrical potential of each coil unit and therefore detects disconnections, short circuiting and earthing of coils based on the obtained electrical phase differences.
SUMMARY OF THE INVENTION
The motor/generator disclosed in Tokkai Hei 11-275826 generates torque fluctuations, noise or vibrations for instance when a disconnection occurs in a coil of the motor/generator or when a circuit component of the inverter malfunctions. Although the motor/generator disclosed in Tokkai Hei 6-311783 detects such mal-functions, it does not comprise a function of preventing torque fluctuation, noise or vibration.
It is therefore an object of this invention to suppress the generation of torque fluctuations, noise and vibration in a motor/generator when a coil is disconnected or a circuit component is mal-functioning.
In order to achieve the above object, this invention provides a drive circuit for such a motor/generator that is provided with a stator and a rotor. The stator comprises a plurality of coils each of which has a first terminal. The rotor rotates due to a rotating magnetic field formed by the coils when a polyphase alternating current is supplied to the first terminals of the coils. The drive circuit to drive this motor/generator comprises a source of direct current, an inverter, a difference detection circuit and a plurality of signal generating circuits. The inverter converts the direct current to a polyphase alternating current based on control signals each of which corresponds to each phase of the current, and supplies the polyphase alternating current to the first terminals of the coils. The difference detection circuit detects a difference in electrical potentials at two different neutral points in an electrical circuit constituted by the motor/generator and the drive circuit. Each of the signal generating circuits generates the control signal corresponding to each phase of the current in response to the difference in the electrical potentials.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.
REFERENCES:
patent: 5703449 (1997-12-01), Nagate et al.
patent: 5834911 (1998-11-01), Kimura
patent: 6049152 (2000-04-01), Nakano
patent: 6078161 (2000-06-01), Kim et al.
patent: 6-311783 (1994-11-01), None
patent: 11-275826 (1999-10-01), None
Foley & Lardner
Nissan Motor Co,. Ltd.
Riley Shawn
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