SU1564016A1 - Self-sustained traction electric drive - Google Patents

Abstract

The invention relates to autonomous traction electric drives and can be used in the management of heavy-duty mining dump trucks. The purpose of the invention is to enhance the functionality, as well as simplify and increase reliability. The drive contains windings 1, 2 of a synchronous generator connected to bridge rectifiers 3, 4. Windings 5, 6 of the DC motor of DC current through brake resistors 14, 15, shunted respectively by contactors 16, 17, are connected in series with windings 7, 8 of excitation and connected to rectifier m 3, 4 through contacts 9-12 of the reverser. The electric motor is equipped with separation diodes. The cathodes and anodes of the closing diodes are connected respectively to the positive poles of bridge rectifiers 3, 4 and to one of the terminals of the braking resistors 14, 15. The invention provides a non-contact extension of the range of effective electric braking in AC motors with both sequential and electric motors independent arousal. 1 hp f-ly, 2 ill.

Description

The invention relates to an autonomous traction motor drive and can be used, in particular, on heavy-duty mining dump trucks.

The purpose of the invention is to expand the functionality.

FIG. 1 is a schematic diagram of the proposed autonomous traction electric drive with independent supply of the excitation windings of electric motors from an additional source; in fig. 2 is a schematic diagram of an autonomous traction motor with a common power supply of the windings of the core and the excitation of the motors from a synchronous generator.

The autonomous traction electric drive contains a synchronous generator driven in rotation from the prime mover, windings 1 and 2 of which are connected to the inputs of bridge rectifiers 3 and 4, DC motors, windings 5 and 6 of which are connected in series to the output circuits of bridge rectifiers 3 and 4 in a closed loop. The motor windings 7 and 8 are connected in series and connected via contacts 9 - 12 of the reverser to the circuit of another power source 13 (Fig. 1), or they are connected to a closed circuit with rectifiers 3 and 4 and windings 5 and 6 (Fig. 2) . Brake resistors 14 and 15 are included in the same circuit and are bridged by contactors 16 and 17, respectively.

In this case, the windings 7 and 8 of the electric motors are included in a series circuit with the rectifiers 3 and 4, the brake resistors 14 and 15 and the windings 5 and 6, and one of the terminals of each winding 5 and 6 is connected to one of the terminals of the corresponding braking resistor 14 and 15 and the other terminals of the windings 5 and 6 and the braking resistors 14 and 16 are connected to the terminals of the separation diodes 18 and 19, connected in opposite rectifiers 3 and 4. The reverser is made in the form of two independent pairs of contactors 9, 11 and 10, 12.

The drive works as follows.

In current mode, contactors 9 and 11 and contactors 16 and 17 are closed. Bridge

The rectifiers 3 and 4 and the windings 5 and 6 of the electric motors are switched on alternately, sequentially, the currents of the windings of the core and the excitation, and therefore the moments of the electric motors are equal. The drive is controlled by simultaneously adjusting the generator and the current in the windings 7 and 8 (Fig. 1), or only by changing the voltage of the generator (Fig. 2). The movement direction is changed by opening the contactors 9 and 11 and closing the contactors 10 and 12. In the brake mode, the contactors 9, 11, 16 and 17 are open and the contactors 10 and 12 are closed. The current in the windings 7 and 8 and the EMF of the electric motors are reversed, and the braking resistors 14 and 15 are introduced into the circuit of the windings 5 and 6.

At high speeds in the electric drive circuit (Fig. 1), the generator voltage is kept at a minimum level, and a constant value of the core current as speed decreases due to an increase in the current in the windings 7 and 8. At a certain speed, the excitation current and torque of electric motors reaches maximum values and further maintaining constant values of the core current and maximum torque as the speed decreases, is achieved by increasing the generator voltage.

The voltage of the motor decreases in proportion to the reduction in speed,

5a, the voltage of the generator is increased in such a way that the current of the core, determined by the sum of the voltages of the generator and the electric motor, remains constant.

In the electric drive (Fig. 2), due to the presence of separation diodes 18 and 19 with

0 at high speeds, an independent regulation of the current in the windings 7 and 8 is provided. The current through the diodes 18 and 19 is equal to the difference in the currents of the core and excitation. Therefore, at high speeds, as long as the excitation current is less than the core current, the diodes 18

55 and 19 conduct current. The currents of the 5 and 6 koreas are closed in the circuits winding 5 - resistor 14 - diode 18 and winding 6 - resistor 15 - diode 19. The current of the windings 7 and 8 is excited

day flows along the circuit: rectifier 3 — diode 19 — contactor 12 — winding 7 — winding 8 — contactor 10 — rectifier 4 — diode 18 — rectifier 3. By adjusting the generator excitation, the current in the windings 7 and 8 is changed, thereby maintain the set constant current of the core as the speed decreases.

At a certain speed, the excitation current, age, reaches the value of the current core, the diodes 18 and 19 are closed and a series circuit is formed: rectifier 3 - winding 6 core - resistor 15 - contactor 12 - winding 7 - winding 8 - contactor 10 - rectifier 4 - winding 5 - resistor 14 - rectifier 3.

With a further decrease in speed, the stabilization of the set values of the core current and the torque of the electric motors is achieved by increasing the generator voltage and energy consumption from the primary motor.

When electric motors of independent excitation are used in the electric drive, their windings 7 and 8 are connected to an additional power source, for which an additional winding on the stator of the traction generator or an additional synchronous machine with a thyristor rectifier at the output is used. In this case, the diodes 18 and 19 in the circuit of the drive off. In addition, when using an electric drive (Fig. 1), a short-term increase in the braking torque is possible in the zone of high speeds due to an increase in the voltage of 0

five

five

0

five

0

generators and, therefore, the current of the electric motors.

Claims (2)

1. An autonomous traction electric drive containing a synchronous generator driven by a primary motor, the windings of which are connected to the inputs of bridge rectifiers, DC motors, the coil windings of which are connected in series to the output circuits of bridge rectifiers in a closed loop, and the field windings are connected and in series through the contacts of the reverser in the circuit of another power source, brake resistors and contactors, characterized in that, in order to expand the functional, Tei, brake contactor shunted resistors and included in the series circuit of bridge rectifiers and winding armatures closed loop. 2. The electric drive according to claim 1, characterized in that, in order to simplify and increase reliability, it is equipped with separation diodes, and the excitation windings of the traction motors are connected in series with bridge rectifiers, braking resistors and windings of Korea From the terminals of each winding, the cores are connected to one of the terminals of the corresponding braking resistor, and the other terminals of these windings of the cores and braking resistors are connected to the terminals of the corresponding separation diodes connected in opposite directions. Stove rectifier m. Fig 2