SU783937A2 - Device for limiting dc electric motor load current - Google Patents

Description

The invention relates to the field of electrical engineering and can be used in electric drives with adjustable converters, where it is necessary to limit the current of the electric motor body during both overloads and transients. According to the main author. St. No. 457155, a device for limiting the load current of a direct current motor, including a controllable converter, to which a direct current motor is connected with an excitation winding; Thermal-dependent voltage divider, containing two resistors with a low temperature coefficient of resistance and a thermistor with a negative temperature coefficient of resistance, is connected to the additional poles and compensation windings of the electric motor. A voltage divider arm containing a resistor and a thermistor is connected via a current-limiting node to the regulator input in the converter control circuit. l The disadvantage of the known device is the relatively low accuracy of stabilization of the stopping current in the middle of the range of temperature variation of the additional advantages and compensation windings. The purpose of the invention is to improve the accuracy of the stabilization of the stopper current over the entire working range of the temperature change of electric machines, which will improve the reliability and performance of the drive and mechanism. This is achieved by the fact that in a known device for limiting the load current of a direct current electric motor according to Aut. Ev 457155 parallel to the shoulder of a thermo-dependent voltage divider, not connected to the controller input, is connected to a chain containing a series-connected resistor and a semiconductor thermistor with a positive temperature coefficient of resistance. In FIG. 1 shows a schematic diagram of the proposed device; in fig. 2 shows the dependences of the error of stabilization of the stopping current. From the temperature for the prototype device (a) and the proposed device (b). . . The device contains a controlled converter 1 to which the electric motor 2 is connected with excitation 3, to the pole 4 and compensation windings 5

Iyyuyuchen tiger-dependent voltage divider, containing two resistors b and 7 with a low temperature. resistance factor and semiconductor thermistor 8 with a negative temperature coefficient of resistance. Resistors 7 and 8 form a quadrupole, the output of which through the current-limiting node 9 is connected to the controller input in the converter control circuit. To improve the accuracy of stabilization of the parallel current, parallel to the thermo-dependent voltage divider arm, not connected to the controller input, a chain is connected containing a series-connected resistor 10 with a negligible temperature coefficient of resistance and a semiconductor thermistor 11 with a positive temperature KEL and a nonlinear dependence of the temperature on temperature -.

: ry.

The proposed device can be applied as in the case of current limiting node implementations using

current feedback loop, jrag; subordinate control systems that use linear current feedback.

The device works as follows.

; Thermistors 8 and 11 are placed

in direct thermal contact with additional poles or a compensation winding. When changing, the temperature of the windings of the additional poles or compensation windings changes the temperature and, accordingly, the resistance of semiconductor thermistors 8 and 11. Equivalence, non-linearity of characteristics: thermistors 8 and 11, the output voltage of the quadrupole, which is a function of the current in the core circuit, in the working The temperature range of the neglect temperature is little dependent on the heating of the additional poles or compensation windings. ,, .., „

In the proposed device can be provided as accurate compensation, as well as recompensation of the stopping current.

The advantage of the proposed arrangement is that the accuracy and bieieration of the Toira stopper is observed throughout the entire working range of the temperature variation of electrical systems.

As a vidnr from the dependences of the TSPH and | ZE: |) SH11YV stopwire-current (flci; from the heating temperature of the additional prusi or compensation windings V, shown in figure 2. The stabilization accuracy of the stopper

783937

current in the operating temperature range (0-100 ° C) in the proposed device n. much higher than in the known. Dependency o1st. f (v) for the proposed scheme was calculated by the formula

- (T-ToKR.Ho. P,)

: .-.

MO

eleven

0 where cL is the temperature coefficient

copper resistance oL - 0,004 1 / ° C; T - temperature, ° K; T - absolute temperature

273 K;

R, R. the resistance values of the thermo-dependent voltage-divider resistors thus calculated, so that the dependence cTl TI (v) had a minimum value in the range of operating temperatures for heating electric machines; 1., B - constant coefficients for a given thermal cutter with a negative temperature coefficient;

-R. - resistance value of a thermistor with a positive temperature coefficient at temperature T; p; - (about the magnitude of the voltage taken from the output of the quadrupole;

 BTwoTc the voltage taken from the additional poles and compensatory windings at a cut-off current and lore and a temperature of about C.

The stability of the stopping current during operation makes it possible to economically use the drive, increase the reliability of operation, and increase the service life of the electric drive AND mechanism. Foriula of the invention

A device for limiting the load current of a permanent-stroke motor for ajBT. St. 457155,: about the fact that, in order to improve the stabilization of the stopping current in the operating range of the heating temperature of electric machines, a chain is connected parallel to the thermo-dependent voltage divider arm, not connected to the controller input, containing a series-connected resistor and semiconductor thermistor

0 with a thermal temperature coefficient of resistance.

Sources of information taken into account in the examination 1. USSR author's certificate

5 457155, cl. H 0 P 5/06, 1967.

XL

/

-.

Claims (1)

Claim . be 'tion and overcompensation of the holding' current. ./. .. The advantage of TV on the proposed device is to increase the accuracy of the stabilization of the stop tog throughout the entire operating temperature range of electric machines J As can be seen from the dependences relative to the `` ~ e ''s5o``Ly'yak''y0Yb'ё ^^ 'орно орно орно орно · current · current ilcT' ^on the heating temperature of the additional β-poles or compensation windings v, shown in Fig.2. stop stabilization accuracy A device for limiting the load current of a DC motor according to ed. St. No. 457155, it is noteworthy that, in order to increase the stabilization accuracy of the stop current in the operating range of the heating temperature of electric machines, a chain is connected parallel to the shoulder of the temperature-dependent voltage divider, which is not connected to the input of the regulator, containing a series-connected resistor and a semiconductor thermistor with a positive temperature coefficient of resistance.