RU60447U1 - DC CONTROL SYSTEM OF CONTROLLED ELECTRIC MOTORS - Google Patents

Abstract

The utility model is aimed at improving reliability and efficiency. control systems, simplification of the scheme, the implementation of energy recovery of engines back to the power line during braking. The specified technical result is achieved in that between the plus and minus of the power line are connected in parallel: series-connected first and second electronic keys, series-connected third and fourth electronic keys, series-connected rheostat and fifth electronic key, as well as a capacitor. Moreover, each of the anchors of the first and second motors is connected to a common point of the third and fourth electronic keys and AC inputs of the first and second rectifiers, moreover, the second AC inputs of these rectifiers are connected to a common point of the first and second electronic keys. The first and second field windings of each of the motors are connected to the DC inputs, respectively, of the first and second rectifier. 1 ill.

Description

Control system for DC motors of series excitation

The utility model relates to control systems for DC motors of sequential excitation, which can be used as traction motors of vehicles, as well as lifting and loading facilities.

A known control system for DC motors of sequential excitation [Kit electric equipment for mine contact electric locomotives weighing 14 tons, http://www.laborant.ru/eltech/10/0/4/18-97.htm] selected as a prototype, containing a plus power line connected through the first mechanical contactor to the anode of the first diode. The cathodes of the first and second diodes are connected, and the anode of the second diode is connected to the negative of the power line. The first terminal of the armature of the first motor and the anode of the first thyristor are connected to the cathodes of the first and second diodes. The second terminal of the armature of the first motor is connected to the anodes of the second and third thyristors, and the cathodes of the first and second thyristors are connected to the first terminal of the armature of the second motor. Cathode of the third thyristor and

the second terminal of the armature of the second motor are interconnected and connected to the cathode of the third diode and the first terminal of the reversing contactor. The second and third terminals of the reversing contactor are connected in series with the field windings of the first and second motors. Between the fourth terminal of the reversing contactor and the minus of the power line are connected in parallel: a second mechanical contactor, a rheostat and a thyristor contactor. The first terminal of the exciter is connected to the negative side of the power line, and the second to the anode of the third diode.

The disadvantages of this control system for DC motors of sequential excitation are low reliability due to the presence of mechanical contacts, as well as low efficiency in starting and braking modes due to the use of a rheostat, as a means of regulating current. In addition, the presence of a pathogen and a third diode, necessary to ensure effective braking, complicates the scheme.

The objective of the utility model is to increase reliability and efficiency control systems, the implementation of energy recovery of engines back to the power line during braking, simplification of the circuit.

The problem is solved due to the fact that the control system of DC motors of sequential excitation, also

as in the prototype, it contains plus and minus power lines, armature and field windings of two motors and a rheostat.

According to a utility model, between the plus and minus of the power line are included: series-connected first and second electronic keys, series-connected third and fourth electronic keys, series-connected rheostat and fifth electronic key, as well as a capacitor. Each of the anchors of the first and second motors is connected by one terminal to a common point of the third and fourth electronic keys, and each other terminal, respectively, to the first AC input of the first and second rectifiers. The second AC inputs of the rectifiers are connected to a common point of the first and second electronic switches, and the first and second field windings of each of the motors are connected to the DC inputs of the first and second rectifiers, respectively.

Using a modern element base, for example, transistors as electronic keys, allows you to increase the switching frequency of electronic keys and, as a result, use their own inductance to limit the current of motors, i.e. heat losses during heating of the rheostat are eliminated, which increases the efficiency system allows for non-reactive start-up. Using motor inductance also allows

implement regenerative braking. The structure of the proposed system allows you to get rid of the exciter without reducing the effectiveness of braking.

Figure 1 presents the structural diagram of a control system for DC motors of series excitation.

The claimed control system for DC motors of sequential excitation consists of series-connected first (EK1) and second 2 (EK2) electronic keys, of sequentially connected third 3 (EKZ) and fourth 4 (EK4) electronic keys, series-connected rheostat 5 (P) and the fifth electronic key 6 (EC5), as well as the capacitor 7 (K), which are simultaneously connected between the plus and minus of the power line. The first 8 (Я1) and second 9 (Я2) engine anchors with one terminal are connected to a common point of the third 3 (EKZ) and fourth 4 (EK4) electronic keys. Each other terminal of the first 8 (Я1) and second 9 (Я2) anchors is connected to the first AC input, respectively, of the first 10 (В1) and second 11 (В2) rectifiers. The second AC inputs of the rectifiers 10 (B1) and 11 (B2) are connected to a common point of the first 1 (EC1) and second 2 (EC2) electronic keys, and the first 12 and second 13 excitation windings of each of the motors are connected to the DC inputs, respectively , the first 10 (B1) and second 11 (B2) rectifiers.

As electronic keys 1 (EC1) - 4 (EC4) and 6 (EC5), lockable thyristors, bipolar (including with an isolated gate) or field-effect transistors with built-in or external reverse diodes can be selected. As rectifiers 10 (B1) and 11 (B2), half-wave diode bridges can be used, including bridges with synchronous rectification.

The control system for DC motors of sequential excitation regulates the currents of the motors in traction and braking modes when the motors rotate in both directions. To maintain the required magnitude of the motor current, the electronic keys are periodically switched, and the ratio of the duration of the on state to the on period is proportional to the current of the motors.

In the thrust mode, the electronic key 4 (EC4) is closed continuously, and the first 1 (EC1) and second 2 (EC2) electronic keys are closed in phase, while the current of the motors flows either from the plus of the power line to minus through the closed first 1 (EC1) and fourth 4 (EC4) electronic keys, the first and second rectifiers 10 (B1) and 11 (B2), the first and second field windings of the motors 12 and 13, the armature of the first and second motors 7 (Y1) and 8 (Y2), or under the action of their own inductors of motors through a closed fourth 4 (EC4) electronic key and a closed second (EC2) electronic th key

or its reverse diode, the first 10 (B1) and second 11 (B2) rectifiers, the first 12 and second 13 of the field winding of the motors, the armature of the first 8 (Y1) and second 9 (Y2) motors.

In braking mode, a constant voltage is present at the armature of the motors, the motors operate in generator mode. Current flows through a closed second electronic key 2 (EC2), a closed fourth electronic key 4 (EC4) or its reverse diode, the armature of the first and second motors 8 (Y1) and 9 (Y2), the first 10 (V 1) and second 11 ( B2) rectifiers and, the first 12 and second 13 excitation windings of the motors. In the process of braking due to the intrinsic inductance of the motors, their energy enters the supply network and capacitor 7 (regenerative braking). If the supply network is not able to receive the energy coming from the circuit and the voltage in it begins to increase, then the fifth 6 (EC5) electronic switch closes and the excess energy is dissipated by rheostat 5 (P) (electrodynamic braking).

When the engine rotates in the opposite direction, the operation of the circuit in traction and braking modes is similar to the above cases, however, the first 1 (EC1) and second 2 (EC2), fourth 4 (EC4) and third 3 (ECZ) electronic keys, respectively, change roles.

In the case when the engine speed is low and the above braking modes are not effective, apply

opposition, i.e. traction mode is used, but in the direction opposite to rotation. If during the transition to the braking mode there is no voltage at the armature of the motors, then, to excite them, braking by means of a short circuit is applied for a short time, and then regenerative or electrodynamic braking is used.

Claims (1)

A control system for DC motors with series excitation, containing plus and minus power lines, armature and field windings of two motors, a rheostat, characterized in that the first and second electronic keys are connected in series, the third and fourth electronic keys are connected in series, the rheostat and fifth electronic are connected in series the key, as well as the capacitor, are connected in parallel between the plus and minus of the power line, while each of the anchors of the first and second motors is connected to a common the point of the third and fourth electronic keys and the AC inputs of the first and second rectifiers, the second AC inputs of these rectifiers being connected to a common point of the first and second electronic keys, and the first and second field windings of each of the motors are connected to the DC inputs, respectively, of the first and second rectifiers.