Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1998-05-27
2000-08-29
Enad, Elvin
Electrical generator or motor structure
Dynamoelectric
Rotary
310 68B, 310 68D, 310 68R, 310 68A, H02K 1100
Patent
active
061113301
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND INFORMATION
A safety circuit is described in U.S. Pat. No. 4,307,325 for a direct current motor, which is used, in particular as a drive motor for tools. The motor is protected against excess temperature by estimating the motor temperature on the basis of a calculation. The calculation takes into consideration both the rpm rate as well as the motor current or the current conduction flow angle of a phase segment control.
SUMMARY OF THE INVENTION
According to the present invention, in order to detect the temperature of the armature of a direct current motor, the temperature is detected in an indirect manner from the temperature-dependent armature resistance, the armature resistance being determined as the quotient of the voltage being applied to and measured at the motor terminals and the respective temperature.
According to the present invention, the blocking current is determined by extrapolation of the armature current determined at a specific point in time.
The present invention provides for the measurement, and where necessary, for the amplification of the current flowing into the armature via a shunt resistor, and for the digitization of the current into a current signal via an analog-digital converter.
According to the present invention, the current signal determined from the current flowing in the armature is averaged with adjustable, calculated integration times with the aid of an integrator controlled by a microcontroller.
According to the present invention, the current signal determined from the current flowing in the armature is integrated over numerous commutation periods.
The present invention provides that the integration of the current signal determined from the current flowing in the armature is interrupted when a threshold value is exceeded, the determined value is digitized and stored, integration begins anew with this process continuing until the entire adjusted and intended integration time has elapsed.
The present invention can be very practically used for the indirect determination of the rpm rate of a motor and/or variations that are critical or of interest in the rpm rate of a motor.
According to the present invention the rpm rate is proportional to the voltage induced in the armature in accordance with equation N=.kappa..multidot.U.sub.ind, taking into consideration a motor-typical proportionality constant with the voltage induced in the armature being determined as the difference between the voltage applied at the motor terminals and the product of the armature voltage by the armature resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a typical variation of the motor current together with superimposed commutation fluctuations, and
FIG. 2 shows an exemplary block diagram of the arrangement according to invention.
DETAILED DESCRIPTION
In accordance with the present invention, the temperature in a direct current motor or in the armature of a direct current motor is determined in an indirect manner. The temperature is determined in an indirect manner from the temperature-dependent armature resistance R.sub.A. The armature resistance R.sub.A itself is determined as the quotient of the measurable voltage U.sub.kl applied to the terminals of the motor, which, when connected to a battery, especially a vehicle battery, corresponds to battery voltage U.sub.bat, and the blocking current I.sub.block of the armature, and set in relation to the respective temperature. In the following description, the generally known relationship of measured resistance and associated temperature is not dealt with in greater detail.
FIG. 1 shows the typical variation of motor current I together with superimposed fluctuations in commutation plotted against time axis t. The armature current is limited by armature inductivity. Consequently, blocking current I.sub.block does not flow at the instant of switch-on, but instead there occurs an exponentially increasing armature current having an electric time constant of .tau..sub.electric which is considerably less than .tau..sub.mech. Peak s
REFERENCES:
patent: 5281919 (1994-01-01), Palanisamy
patent: 5291115 (1994-03-01), Ehsani
patent: 5497218 (1996-03-01), Amico
patent: 5583404 (1996-12-01), Karwath et al.
patent: 5672948 (1997-09-01), Cohen et al.
patent: 5717297 (1998-02-01), Karwath et al.
Aab Volker
Knecht Gerhard
Lochmahr Gunnar
Enad Elvin
Robert & Bosch GmbH
LandOfFree
Arrangement for sensing the temperature of the armature of a dir does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Arrangement for sensing the temperature of the armature of a dir, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Arrangement for sensing the temperature of the armature of a dir will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1252950