SU769694A2 - Device for two-zone regulating of speed - Google Patents

Description

one

The invention relates to the field of control of electric motors, in particular, devices for controlling the speed of electric motors used in controlled transducer-motor systems, having a different static moment on the shaft, in which the voltage on the crust and the excitation current of the motor are controlled.

According to the main author. swith No. 568131, a device for two-variable speed control is known, comprising a driver, a voltage regulator with an output limiter in its feedback circuit, and a current controller connected in series with each other and a valve converter, as well as an excitation controller and voltage sensors. core and excitation current, nonlinearity unit; moreover, the limiter is connected via an adder and a nonlinearity unit with a voltage sensor and through the same adder and a nonlinearity unit with an excitation current sensor. The current sensor core is connected through an additionally introduced non-linear unit to the input of the field current controller, and parallel to the input of the field current controller is connected a limiter, to the input of which the voltage sensor 1 is connected.

This device is applicable for controlling the speed of mechanisms with a small static moment and a large moment of inertia, such as turning mechanisms.

5 excavator - dragline, but it does not provide reliable control of the speed of electric drives of mechanisms with constant power, as well as mechanisms with long static overloads

10 torque and low rotation speed. The aim of the invention is to increase the reliability when the motor is operated in the mode of long-term static overload.

15 The goal is achieved by the fact that a sensor for changing the resistance of the windings of the core circuit, a diode, a potentiometer and a zener diode are inserted into the device, while the sensor for the value of changing the resistance

20 through a diode connected to the terminals of a potentiometer consisting of a thermistor connected in series, installed in the cooling air flow at the motor inlet, and a resistor, one of

25 terminals of the potentiometer are connected to the input of the nonlinearity unit, and the midpoint of the potentiometer is connected via a zener diode to the additional input of the adder. Moreover, the sensor of the magnitude of the change in the resistance of the core circuit contains a direct current transformer and a diode bridge connected 3 to the main winding circuit, the output of each of which is bridged by a parallel resistor and a capacitor. 5 Introduction to the value of the main winding, in series with the connected sensor of the value of the winding resistance The rotor circuit and the location of the thermistor in the cooling air flow at the 10th entrance to the electric motor allow monitoring the deterioration of the cooling conditions and overheating of otok anchor chain and function of these parameters to regulate the voltage across the cortex, and hence reduce the current of the armature 15 when the temperature exceeds the allowable zpacheni windings. FIG. 1 shows the proposed device, a block diagram; in fig. 2 - sensor 20 of the magnitude of the change in the resistance of the windings of the core circuit. The device for two-zone speed control contains a block 1 of the task and voltage regulators 2 and current 3 kor connected to it and between them, a valve converter 4, to the outputs of which current input 5 is connected and one of change input 6 resistance of the fd-30 current core, included in the core chain. The outputs of sensor 6 are connected to the terminals of potentiometer 7, one through diode 8 from the side of a constant resistor 9, and the other from the side of a thermistor 10. To one of the 35 inputs and the output of the voltage regulator 2 are connected the AC input of the diode bridge 11, and The current of the said bridge 11 is connected to a resistor 12 and an output of the adder 13. The first input 40 of the latter is connected to the output of the nonlinearity unit 14, the second through the Zener diode 15 to the midpoint of the warmthmeter 7, the third to the output of the nonlinearity unit 16, the fourth to the output of the block 14 -45 line yna, clamping potentiometer 7 from the side of the thermistor 10 and the output of the block 16 nonlinearity. In parallel with the working brushes of the electric motor 17, the inputs of the voltage sensor50 18 are connected, the output of which, together with the input of the nonlinearity unit 14, is connected to the input of the voltage regulator 2. The excitation current sensor 19 is connected in series with the windings of the airflow 20 and the outputs with the input of the converter converter 21. The sensor 6 of the magnitude of the change in the resistance of the core circuit windings (Fig. 2) contains a transformer 22 of direct current connected by its inputs 60 in series with the windings of the additional poles 23 and. compensatory 24, diode bridge 25, the AC inputs of which are connected in parallel with the mentioned windings 23 and 24. The postage terminals of the DC outputs of the transformer 22 and the diode bridge 25 are interconnected with one terminal of capacitors 26, 27 and resistors 28, 29. The negative terminals of the outputs of the transformer 22 and the diode bridge 25, connected respectively to the resistor 29, the capacitor 27 and to the resistor 28, the capacitor 26, are the output of the sensor 6. The device for two-zone speed control works as follows . At the beginning of the operation after a long period of stationary installation of the unit, the voltage drop module on the windings of the crustal circuit 23 and 24 is equal to the voltage module at the output of the transformer 22 of direct current. Therefore, the constant component of the output of the diode bridge 25 is closed through the resistor 28, and the variable component is connected through the capacitor 26. The output current of the transformer 22 is closed through the resistor 29 and filtered by the capacitor 27. Due to the equality of the signals at the output of the transformer 22 and the bridge 25, for example, The output of sensor 6 is zero. Therefore, at the additional input of the adder 13, the signal is also zero. When a signal appears on block 1, the output of regulator 2 is set to the voltage determined by the voltage at the AC output of the diode bridge 11, while the current regulator 3 causes the appearance of a small current in the core, which does not cause an increase in the excitation current and magnetic flux. Therefore, acceleration of the electric motor before the selection of all gaps in the gears occurs with a reduced moment, which ensures a small amount of impact at the moment of the end of the selection of the gap and an increase in the current of the electric motor. This causes an increase in the voltage at the output of the sensor 19 of the excitation current and at the input of the adder 13, which leads to an increase in the acceleration current of the core. This positive feedback action ends when the maximum voltage is reached at the output of the adder 13. In this case, the excitation current of the electric motor increases to a value that ensures the full saturation of the electric motor. Negative feedback on the excitation current of the electric motor ensures timely removal of the excitation voltage on the excitation voltage. Connecting the input of the nonlinearity unit 16 to the output of the sensor 19 provides positive feedback, which contributes to the output of all motor parameters to the maximum permissible level. As the motor speed increases, the windings of the core chain are heated, and the resistance of the windings 23 increases.

and 24, and the voltage drop module on them from the core current becomes greater than the voltage module at the output of the transformer 22. Moreover, the difference of these modules, allocated at the output of sensor 6 and applied to potentiometer 7, repeats the curve of change in current of core. When the temperature of the windings is within acceptable limits, Zener diode 15 will be locked, and the operation of the circuit is determined from the conditions for ensuring reliable switching. An increase in the motor speed causes an increase in the voltage on the core, resulting in a decrease in the voltage at the input of the adder 13, and through a diode bridge 11 causes a decrease in the voltage on the regulator 2, and hence the current of the core.

With further heating of the root winding and the windings of the additional poles 23 and compensatory 24, the voltage applied to the Zener diode 15 at some time exceeds the voltage of its opening. As a result, the voltage at the output of the adder 13 will be corrected by the resulting additional feedback on the change in resistance, i.e. by changing the temperature of the windings of the core chain. The change in the voltage of the adder 13 is also determined by the change in the temperature of the input W, its air motor. Thus, for example, with increasing temperature, the input W, of its air, which primarily characterizes the deterioration of the cooling conditions of the most thermally loaded winding core, the opening of the Zener diode 15 occurs earlier due to an increase in the resistance value and a change in the potentiometer division ratio.

After reducing the voltage of the backup at the outputs of the direct current of the diode bridge 11, the voltage at the input of the voltage regulator 2, regardless of the voltage at the output of the task unit 1, decreases. Therefore, the voltage at the output of current sensor 5 of the core and the input of the current regulator 3 is compared with a smaller signal, which leads to a decrease in the voltage at the output of the regulator 3 and converter 4, and, therefore, the current of the core and heating of the windings.

Diode 8 protects the circuit from an unacceptable increase in the current of the core when the motor is cooled below the temperature at which the selection of the parameters of sensor 6 was made.

Monitoring the heating of the core windings, monitoring the deterioration of the cooling conditions, and regulating the current of the core as a function of these quantities make it possible to increase reliability

control of electric motors in the modes of continuous overloads by static moment, for example, the rotor and winches of drilling rigs, the drive for moving the table of the longitudinal planing machines, etc.

Claims (2)

1. Device for two-zone speed control according to the author. swith No. 568131, characterized in that, in order to increase reliability when the motor is operating in a continuous static overload mode, a sensor for changing the resistance of the core circuit, a diode, a potentiometer and a zener diode are inserted into it, and the sensor for changing the resistance value is diode-connected to the terminals a potentiometer consisting of a thermistor connected in series, installed in the cooling air flow at the motor inlet, and a resistor, one of the potentiometer terminals is connected to the inlet block ode nonlinearity, and the middle point of the potentiometer through the Zener diode is connected to the additional input of the adder. 2. The device according to claim 1, characterized in that the sensor of the magnitude of the resistance change of the windings of the core circuit contains a DC transformer and a diode bridge connected to the core circuit, the output of each of which is connected by a parallel connected resistor and a capacitor. Sources of information taken into account in the examination 1. USSR author's certificate No. 568131, cl. H 02R 5/26, 1973 (prototype).