SU1515312A1 - D.c. electric drive - Google Patents

Abstract

The invention relates to electrical engineering and may find application in various mechanisms operating under unstable voltage of a power source. The aim of the invention is to improve the accuracy of stabilization of the rotational speed and reliability. A parallel excitation winding 10 in series with a nonlinear resistor 11 is connected between the contact 7 of the linear contactor 8 and the common point of the windings of the core and additional poles. A two-stage transistor 13,14 amplifier is introduced into the electric drive, the first of which is controlled by a voltage drop signal on the winding of 3 additional poles, and the second shunts, depending on the operating mode, a nonlinear resistor 11 in the excitation winding circuit 10. The rotation frequency is stabilized due to the effect of the core current on the magnitude of the excitation current, improves the commutation under increased voltage of the power source. In addition, regulation of the start and stop processes by the action of a transistor amplifier on the excitation circuit of an electric motor is achieved. 1 hp f-ly, 2 ill.

Description

The invention relates to electrical engineering and can be used in various mechanisms operating under unstable voltage of the power source.

The aim of the invention is to improve the accuracy of stabilization of the rotational speed and reliability.

FIG. 1 shows a schematic diagram of the electric drive; Fig 2 is a diagram of a device with a transistor amplifier.

DC power supply

(FIGS 1) contains an uncompensated DC motor, the root circuit of which is composed of a series-connected stabilizing winding I, windings 2 core and 3 additional poles, and is connected to the power supply 4 by the extreme output of the stabilizing winding 1 via a starting resistor 5,

bypass contactor 6

-I acceleration, and the first contact 7 of the linear contactor 8, and the extreme output of the winding 3 additional poles through the second contact 9 of the linear contactor 8. The winding 10 of the parallel excitation is connected to one common point of the starting resistor 5 and the first contact 7 of the linear contactor 8, and another through a nonlinear resistor 11 - with a common point of the winding

2 core and winding 3 additional poles. The motor is associated with a load of 12.

The DC motor (Fig. 2) additionally contains two transistors 13 and 14, a smoothing T-shaped RC filter 15, a closing contact 16 of the Stop button, a disconnecting block contact 17 of the accelerator contactor, two resistors 18 and 19, a zener diode 20 and a diode 21, The emitters of transistors 13 and 14 are connected to a common point of the windings 2 core and 3 additional poles, a baso-emitter junction of the first transistor 13, shunted by a diode 21, through a smoothing T-filter 15. Connected to the winding

3 additional poles. The transition emitter - collector of the second transistor 14 is connected in parallel to the nonlinear resistor 11, the base through the first resistor 18 is connected to its transmitter, and through the Zener diode 20 to the collector of the first transistor 13 connected through the second resistor

19 to a common point in parallel of the closing contact 16 KHonKii Stop and disconnecting block contact 17 of the accelerator contactor, the second common point of which is connected to the first contact 7 of the line contactor 8.

The actuator (Fig. 1) works as follows.

After the line contactor 8 trips, a rheostatic motor start occurs, in which the core current is limited by the starting resistor 5. Then the accelerator contactor is actuated (the winding and control circuits are not shown) and the start resistor 5 is withdrawn from the core circuit, After the motor accelerates, its speed stabilizes the account indicated in FIG. 1 connection winding 10 parallel excitation. Increasing, for example, the core current decreases the current of the winding 10, which accordingly leads to a decrease in the magnetic flux and the transition of the operating point of the electric motor to the overlying electromechanical characteristic. As a result, the static mechanical characteristic of the electric drive has a greater rigidity, i.e. a smaller dependence of the rotation frequency on the load, as a result, the accuracy of the stabilization of the rotational speed of the motor is increased. In this case, the change in the rotation frequency due to fluctuations in the voltage of the power supply source 4 is compensated by the change in the current of the winding 10 due to the nonlinear resistor 11.

In addition, in the electric drive, the winding of 3 additional poles is automatically fed by the excitation winding 10, which ensures sparkless operation of the electric motor during Increased voltages of the power supply 4, as a result, the wear of the collector-alkaline unit is reduced and the reliability of the electric drive is increased.

When the electric drive circuit (Fig. 1) is supplemented with a transistor amplifier (Fig. 2), I realize an additional reduction of losses and a reduction of electrical loads on the elements in the transient mode;

The actuator (Fig, 2) works as follows.

On the initial start-up step, the electrical current of the electric motor circuit is limited by the starting resistor 5, the first transistor 13 is closed on the base-emitter junction by locking voltage created by the current of the core on the winding of 3 additional poles of the motor, the second transistor 14 is open due to the flow of the base current and, by shunt the open collector junction nonlinear resistance 11, provides the highest value of the current and magnetic flux of the excitation winding 10 of the electric motor. Therefore, the initial acceleration of the electric motor occurs with the highest starting torque and accelerated, due to which the time of a rheostatic start-up is reduced and the electrical loads on the electric drive elements (starting resistor, measles, etc.) are reduced.

Then, when a certain amount of anti-EMF is reached, the engine and its starting current decreases, the closing force contact 6 of the accelerator contactor shunts the starting torus 5 and the electric motor core circuit and transfers it to the natural electromechanical characteristic.

At the same time, due to opening of the auxiliary contact 7 of the accelerator contactor in the base circuit current broming circuit of transistor 14, the electromagnetic process of reducing the current and magnetic flux in the excitation winding circuit 10 begins, at which the motor switches to an artificial electromechanical characteristic, where it works for an indefinite time at the point steady state operation.

In this mode of operation of the electric drive, both transistors 13 and 14 are in the closed state, the nonlinear resistance 11 is introduced into the circuit of the excitation winding 10, and the rotational frequency is maintained relative to the set nominal one.

To disconnect the electro-actuator, a stop switch is manually pressed, the main opening contact of which breaks the power supply circuit of the linear end / actor 8 winding, and the additional closing contact 16 of the stop button connects the resistor 19 of the interstage communication circuit of transistors 13 and 14. At the same time

due to the electromagnetic and mechanical inertia, the disconnection of the linear contactor 8 and the opening of its contacts 7 and 9 occurs with a time delay (0.1-0.3 s), during which a transition occurs in the drive of the engine to the brake (generator) mode, due to forcing the current and magnetic flux of the excitation of the winding 10 during clamping of the nonlinear resistance 11 in the ed circuit by the unlocking transistor 14.

At the moment of changing the polarity of the current in the engine's korna circuit, the polarity of the voltage across the winding of 3 additional poles connected by means of a smoothing T-shaped

RC filter 15 with a base-emitter junction of the first transistor 13. Unlocking the transistor 13 causes the transistor 14 to be locked, passing to the vibration (relay)

the operation mode with pulse-width switching on by switching off the shunt non-linear resistor 11 in the circuit of the excitation winding 10. As a result, the current of the core circuit is limited at some level due to self-oscillations made by it in the stabilization circuit of the braking current of the engine, which is formed by the winding of 3 additional poles (as a sensor

the input current of the electric drive), smoothing the T-shaped RC filter 15, a two-stage amplifier on transistors 13 and 14, loaded on a nonlinear resistance 11, circuit

10, 11, the engine excitation and the core circuit, the magnitude of the back EMF, which is associated with changes in the magnetic flux of the excitation winding 10.

Thus, as a result of the forced reduction and stabilization at a low level of the current of the motor's crust, the opening of the power contacts 7 and 9 of the linear contact 8

occurs almost without arcing, which increases the reliability and service life of the electric drive.

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Claims (2)

Invention Formula 1, A DC electric drive containing an uncompensated DC motor, the root circuit of which is composed of a series of core windings and additional poles connected in series to the stabilizer of o6MOTKHi and intended for the poles. for connecting to the power supply the extreme output of the stabilizing winding through the starting resistor, shunted by the contact of the accelerator contactor, and the first contact of the linear contactor, and the extreme output of the winding of the additional poles through the second contact of the linear contactor, the parallel excitation winding connected in series with the nonlinear resistor, t l and h aa y and with the fact that, in order to increase the accuracy of stabilization of the rotation frequency and reliability, the winding of the parallel excitation is connected to the common the point of the starting resistor and the first contact of the linear contactor, and the other through a non-linear resistor with a common point of the windings of the core and additional poles. 2. The actuator according to claim 1, characterized in that, in order to increase reliability, it additionally includes two transistors, smoothing a T-shaped RC filter, the closing contact of the Stop button, the opening contact of the accelerator contactor, two resistors, a zener diode and a diode , while the emitters of the transistor are connected to the common point of the windings of the core and the additional poles of the base-emitter junction of the first transistor, shunted by a diode, through a smoothing T-shaped RC filter connected to the winding of the additional poles, the emitter-collector junction p of the second transistor is connected in parallel to the nonlinear resistor, the base through the first resistor is connected to its emitter, and through the zener diode to the collector of the first transistor connected through the second resistor to the common point of the parallel closed contact contact of the Stop button and the opening contact of the accelerator contactor, the second common point of which is connected to the first contact of the line contactor.