Electricity: motive power systems – Automatic and/or with time-delay means – Motor load – armature or primary or secondary circuit current
Patent
1999-03-02
2000-08-29
Masih, Karen
Electricity: motive power systems
Automatic and/or with time-delay means
Motor load, armature or primary or secondary circuit current
318625, 318696, 318460, 318466, 318254, 318138, 318439, G05B 500
Patent
active
061113808
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention proceeds from a stop and jamming detection system in a stepping motor, in which a signal that is significant for the stop and jamming detection system is determined from the profile of an instantaneous motor variable.
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
In accordance with the present invention, a stop and jamming detection system in an electric motor is provided which analyzes voltage. Thus, the system according to the present invention is more economical than conventional systems.
According to the present invention, an analysis circuit is provided which detects the voltage that is induced in at least one unenergized winding of the stepping motor and is brought about by an energized winding of the stepping motor, and analyzes it as to whether the motor is jammed or movable.
In advantageous embodiments of the present invention, it is possible to perform the analysis by the analysis circuit with regard to a hard jam or an elastic jam.
According to an advantageous embodiment of the present invention, detection of a hard jam is accomplished with the stepping motor at a standstill and in a test step in which one winding of the stepping motor is energized, and the voltage possibly induced in the other winding of the stepping motor, which is substantially zero in the case of a hard jam, is analyzed.
According to another advantageous embodiment of the present invention, the analysis circuit for detection of an elastic jam detects peaks in the induced voltage profile in the unenergized winding. These peaks can be both negative and positive. In an advantageous development of this embodiment of the present invention, the peaks are detected as an elastic jam when a specific threshold is exceeded.
In a particularly advantageous embodiment development, detection of an elastic jam is accomplished with the stepping motor running in a defined slow fashion.
According to an advantageous embodiment of the present invention, the analysis circuit provided for detection of an elastic jam contains a separate comparator for each winding of the stepping motor, the outputs of the comparators each being guided via a diode to a shared. A signal is present at that output when a voltage peak exceeding a threshold occurs in the induced voltages in one of the windings of the stepping motor.
According to another advantageous embodiment of the present invention, the analysis circuit for detection of a hard jam includes a comparator for any arbitrary winding of the stepping motor, to which voltage peaks conveyed via a diode and a voltage divider can be delivered, and in which the comparator is guided directly to the output and emits an output signal if a correspondingly high voltage peak was induced.
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 stepping motor running against a stop is reduced. The stop detection system can evaluat
REFERENCES:
patent: 3732480 (1973-05-01), Hendrickson et al.
patent: 5327053 (1994-07-01), Mann et al.
Eisenhardt Harald
Munz Juergen
Masih Karen
Robert & Bosch GmbH
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