Electricity: motive power systems – Limitation of motor load – current – torque or force
Patent
1999-08-23
2000-11-21
Ro, Bentsu
Electricity: motive power systems
Limitation of motor load, current, torque or force
318696, 388903, 361 23, H02H 504, H02H 7085
Patent
active
061507822
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a stop and jamming detection system in an electric motor, in particular a stepping or commutator motor, of claim 1.
BACKGROUND INFORMATION
German Patent No. 44 19 813 A1 describes an apparatus for operating an electric motor, stepping motor, or commutator motor, which analyzes an overload or jamming of the drive system for which the electric motor is the power source based on a parameter of a current flowing through the electric motor. The parameter can be determined either within a time interval which still lies within the activation operation after a starting time of the electric motor, or at a predefined sampling time which lags the starting point by a certain delay time. The parameter used for the current being analyzed can be the current amplitude, the change in current, or a current difference, which is evaluated as the signal for the stop and jamming detection system. It is essential in this conventional apparatus that the electric motor be at least approximately current-free at the beginning of the aforesaid starting point, and that the time interval or sampling time occur before steady-state motor current is reached.
SUMMARY OF THE INVENTION
A stop and jamming detection system in an electric motor in accordance with the present invention is more cost-effective than the conventional stop and jamming detection system. Advantageously, this is possible without an additional position check-back (e.g. via potentiometers) or motion check-back (e.g. via Hall sensors).
According to the present invention, in addition to the sensing of the current flowing through a winding of the motor, the instantaneous operating voltage and the resistance of the motor winding are sensed. All three parameters are conveyed to an analysis circuit and a determination is made, by comparison with reference values, as to whether the motor is jammed or movable.
A first advantageous embodiment provides for sensing of the resistance of the motor winding to be accomplished by way of a local measurement of the winding temperature.
A second advantageous embodiment provides for sensing of the resistance of the motor winding to be accomplished, with the motor at a standstill, via resistance determination by measuring the voltage drop at a known measurement resistor which can be connected in series with the winding.
A stop detection system according to the present invention, (referring here to jamming as a result of the mechanical stop), increases the convenience of the system in which it is applied, since the noise generated by the motor running against a stop is reduced. The stop detection system can evaluate the number of steps from stop to stop in stepping motors automatically and without additional outlay.
A jamming detection system according to the present invention makes it possible to use fault handling concepts in the event of faults. The overall convenience and flexibility of the system are thereby substantially improved.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically shows a block diagram of the stop and jamming detection system configured in accordance with the present invention; and
FIG. 2 schematically shows an example of a circuit for determining the winding resistance.
DETAILED DESCRIPTION
FIG. 1 schematically depicts a block diagram of the stop and jamming detection system configured in accordance with the present invention. The value of the instantaneous operating voltage, which is ascertained via a sensing circuit 3, is conveyed to an analysis circuit 1 via an input line 2. In a further sensing circuit 4, the resistance of the motor winding is sensed and conveyed via a line 5 to analysis circuit 1. A third sensing circuit 6 determines the instantaneous current which is flowing through the motor winding. The corresponding value is conveyed via a line 7 to analysis circuit 1. The current flowing through the winding of a jammed motor is greater than when the motor is not jammed.
According to the present invention, analysis circuit 1 takes into acc
REFERENCES:
patent: 4888996 (1989-12-01), Rak et al.
patent: 4977507 (1990-12-01), Matsuoka et al.
patent: 4999552 (1991-03-01), Seipelt
patent: 5510687 (1996-04-01), Ursworth et al.
Breitling Wolfram
Eisenhardt Harald
Munz Juergen
Ro Bentsu
Robert & Bosch GmbH
LandOfFree
Process for detecting abutment and blocking in an electric motor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for detecting abutment and blocking in an electric motor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for detecting abutment and blocking in an electric motor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1260689