Electricity: motive power systems – Induction motor systems – Primary circuit control
Utility Patent
1998-10-02
2001-01-02
Ip, Paul (Department: 2837)
Electricity: motive power systems
Induction motor systems
Primary circuit control
C318S773000, C318S776000
Utility Patent
active
06169383
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to motor controllers, and more particularly, to a motor controller that automatically senses whether it has been connected to a delta motor or a wye motor and configures itself in the correct mode for operation with the specific motor configuration.
BACKGROUND OF THE INVENTION
During start up, multiphase motors often experience potentially damaging high inrush currents and starting torques. This can adversely effect the performance of the drive and increase general wear and tear leading to higher maintenance costs. In addition, current peaks during motor start up may also cause voltage disturbances in the power supply. Motor controllers are typically employed to restrict motor torque and reduce high starting currents.
A motor controller operates by selectively opening and closing a plurality of switches connecting the motor terminals to the power source. The operation of the motor is dependent upon the proper regulation of the switches. Solid state motor controllers often employ phase control techniques to gradually increase or decrease the voltage applied to the motor using solid state switching devices.
Multiphase motors generally have their windings arranged in either a delta configuration or a wye configuration. Prior art motor controllers have to be specifically manufactured to operate with either a delta motor or a wye motor. This requires the maintenance of a larger inventory of multiple types of motor controllers to accommodate the different motor configurations and can lead to increased storage costs.
Clearly it would be desirable to use a self adapting motor controller that automatically senses if it is connected to a delta motor or a wye motor and automatically configures itself for operation in a compatible mode. The present invention seeks to achieve these objectives.
SUMMARY OF THE INVENTION
It is a principal object of this invention to provide a new and improved motor controller that automatically senses if it is connected to a delta motor or a wye motor and adapts itself to operate in a compatible mode. More specifically, it is an object of the invention to provide such a motor controller that eliminates the need to maintain an inventory of multiple types of motor controllers designed to accommodate only one type of motor.
An exemplary embodiment of the invention achieves the foregoing object in a motor controller. The motor controller is designed to control a plurality of switching means that are adapted to be connectable between a multiphase power source and the motor windings of a multiphase motor. A configuration detection circuit is operatively connected to the multiphase motor windings and automatically detects if the multiphase motor windings are arranged in a first configuration or in a second configuration. A controller circuit connected between the configuration detection circuit and the switching means responds to the windings being arranged in a first configuration by controlling the switching means in a first mode and responds to the windings being arranged in a second configuration by controlling the switching means in a second mode.
In a preferred embodiment, the plurality of switching means are solid state devices.
In a highly preferred embodiment, the plurality of switching means are triacs or SCRs.
In another form of the invention, the configuration detection circuit may include a sensing circuit that is connectable between the first, second and third supply lines of a multiphase power source and the first, second and third windings of a multiphase motor. The sensing circuit generates an output representative of the voltages across each of the first, second and third switching means, the first, second and third line to line voltages and the first, second and third line to neutral voltages.
The configuration detection circuit may also include a decoding circuit connected to the sensing circuit for determining whether the windings are arranged in a delta configuration or in a wye configuration.
The motor windings can be identified as being in a delta configuration when the first line to line voltage and the voltage across the first switching means are synchronously greater than zero and the second line to line voltage and the voltage across the second switching means are synchronously greater than zero and the third line to line voltage and the voltage across the third switching means are synchronously greater than zero.
The motor windings can be determined to be in a wye configuration when the first line to neutral voltage and the voltage across the first switching means are synchronously greater than zero and the second line to neutral voltage and the voltage across the second switching means are synchronously greater than zero and the third line to neutral voltage and the voltage across the third switching means are synchronously greater than zero.
Other objects and advantages of the invention will become apparent from the following specification taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 3678358 (1972-07-01), Kolatorowicz
patent: 4425539 (1984-01-01), Wills
patent: 4477760 (1984-10-01), Kuznetsov
patent: 4734639 (1988-03-01), Saletta et al.
patent: 4792740 (1988-12-01), Smith
patent: 4910450 (1990-03-01), Parker et al.
patent: 4916376 (1990-04-01), Kume et al.
patent: 5614799 (1997-03-01), Anderson et al.
patent: 5708337 (1998-01-01), Breit et al.
Ip Paul
Siemens Energy & Automation Inc.
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