Electricity: motive power systems – Limitation of motor load – current – torque or force
Patent
1999-06-09
2000-07-11
Ip, Paul
Electricity: motive power systems
Limitation of motor load, current, torque or force
318439, 318430, 318493, H02H 708
Patent
active
060877936
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a circuit arrangement for cycled control of a motor, having an overload detection device.
BACKGROUND INFORMATION
A conventional circuit arrangement of this kind provides a shunt for sensing a motor overload such as can occur, for example, in an engine cooling motor or a fan motor as the vehicle drives through water. The elevated engine current due to the overload generates at the shunt an elevated voltage drop which is sensed for overload detection purposes. The shunt itself generates a not inconsiderable power dissipation, and is also not inconsiderable in terms of cost.
SUMMARY OF THE INVENTION
It is the object of the present invention to make available a circuit arrangement which reliably senses a motor overload and is advantageous in terms of energy consumption and cost.
The overload detection device includes a signal sensing stage with which a voltage peak which occurs at a circuit inductance, and in the event of a motor overload exceeds a predefined threshold voltage, can be sensed. Sensing of the voltage peak occurring at the circuit inductance not only results in reliable signal detection, but the signal is also generated with minimal power dissipation. The voltage peak depends on the motor current, so that the overload can be reliably detected by comparison with the predefined threshold voltage. The circuit inductance can be picked off at a suitable line, in particular on a circuit board.
A favorable pickoff possibility for the voltage peak is offered by the fact that the circuit inductance is constituted by a line inductance in a connecting line of an electrolytic capacitor connected in parallel with the motor.
Signal sensing can be accomplished with simple means by the fact that the circuit inductance is formed at the connecting line to the negative terminal of the electrolytic capacitor, and that the signal sensing stage has, in order to decouple a positive voltage peak, a diode which is connected with its anode to the negative terminal of the electrolytic capacitor and whose cathode is connected to ground via a capacitor and a resistor connected in parallel with the latter.
Simple, reliable sensing of the motor overload is promoted by the fact that the voltage peak is conveyed to one terminal of a comparator stage, at whose other terminal the threshold voltage is formed.
It is advantageous for economical manufacture in terms of components and production that the signal sensing stage is embodied at least partially using SMD technology.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an exemplary embodiment of a circuit arrangement for a motor control system according to the present invention.
FIG. 2 shows a portion of the circuit arrangement shown in FIG. 1, depicting a signal sensing stage.
FIG. 3 shows signal profiles of the circuit arrangement depicted in FIGS. 1 and 2.
DETAILED DESCRIPTION
FIG. 1 shows a circuit arrangement 1 having a motor 2 that is controlled in a cycled manner via an electronic switch S1, preferably in the form of a power MOSFET. Located parallel to the motor 2 is a circuit branch having an electrolytic capacitor C1 as well as a noise-suppression inductor L1 and a mispolarity protector with a further electronic switch 3. Connected between the negative terminal of motor 2 and the positive terminal of electrolytic capacitor C1 is a freewheeling diode D1, with its anode at the motor terminal and its cathode at the positive terminal of electrolytic capacitor C1. A line inductance L2 is located between the negative terminal of electrolytic capacitor C1 and the ground terminal. Circuit arrangement 1 is powered by a battery voltage U.sub.B.
As depicted, for example, in FIG. 2, a signal detection stage of an overload detection device is connected to line inductance L2. The signal detection stage has a diode D2 which is connected with its anode to the negative terminal of electrolytic capacitor C1 and with its cathode to a parallel circuit made up of a capacitor C2 and a discharge resistor R, whose other terminals
REFERENCES:
patent: 3629608 (1971-12-01), Trindle
patent: 3633073 (1972-01-01), Day
patent: 4910445 (1990-03-01), Borrmann
patent: 4980624 (1990-12-01), Bernhardt
patent: 5453669 (1995-09-01), Nishibe et al.
patent: 5719732 (1998-02-01), Nagahama et al.
Patent Abstracts of Japan--vol. 015, No. 014 (E-1022), Jan. 11, 1991; JP 02 262 897 Copy of article has been provided by the International Searching Authority.
Ip Paul
Robert & Bosch GmbH
LandOfFree
Circuit for controlling a motor with a device for recognizing an does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit for controlling a motor with a device for recognizing an, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit for controlling a motor with a device for recognizing an will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-545237