SU915196A1 - Electric drive control device - Google Patents

Description

The invention relates to electrical engineering, in particular to an electric drive, and can be used when starting drives with large inertial masses of actuators and equipped with drive motors having a non-linear mechanical characteristic, for example, asynchronous motors.

Closest to the technical essence and the achieved result is the method of controlling the electric drive, according to which the motor is started and accelerated and connected to an elastic element connected to the actuator, then the motor is stopped, the actuator is disconnected from the elastic element and the actuator is restarted and acceleration of the electric motor with an actuator [1].

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The disadvantage of this method is large energy losses during start-up and acceleration of the electric motor and excessive heating of its windings, due to the fact that the flywheel is connected directly to the engine, the kinetic energy of which is sufficient to accelerate the actuator.

The purpose of the invention is to reduce energy losses during start-up and acceleration of the drive, as well as reducing the heating of the motor windings.

This goal is achieved by the fact that the start and acceleration of the motor

_{) 5} is idle and, when the actuator reaches the speed of rotation of the electric motor, fix the elastic element in the stressed state, storing the potential energy

20th, and after restarting and accelerating the electric motor, the actuator is pre-accelerated using the stored potential energy of the elastic

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element, and at the time when the elastic element completely gives off the accumulated energy, they connect the electric motor to the elastic element.

Figure 1 is a diagram explaining the sequence of operations, according to the proposed method; in figure 2 — the oscillogram of the first start-up and acceleration of the electric drive of the feeding conveyor of the serial semi-automatic line UL0-15C, intended for bucking wood; on fig.Z “oscillogram of the restarting and acceleration of the electric drive.

A device for implementing with. <5 Soba includes an electric motor 1 connected by a controlled coupler 2 to the actuator 3 via an elastic element C, closed by a controlled coupler 5. The shaft connecting the coupling 2 to the elastic element 4 is connected to the brake 6.

The method of controlling the electric drive is as follows:

At the first start of the electric drive, the electric motor 1 is idle first and dispersed, and then, after the electric motor 1 reaches a stable part of the mechanical characteristic, which for an asynchronous motor corresponds to a slip less critical, the motor shaft is attached, for example, using a controlled coupling 2 to the shaft of the actuator 3 through elastic element 4 (for example, a spring ^ having a flexibility sufficient to accumulate slip energy during acceleration of an actuator by the engine and at the point in time when the shaft of the actuator 3 reaches the same rotational speed as the shaft of the driving motor, the kinematic transmission abruptly reduces the flexibility by rigidly coupling the shafts of the electric motor 1 and the actuator 3 ”, for example, using a second controlled coupling 5. In the subsequent next start-up of the electric drive, the potential energy stored in the elastic element 4 during the previous start-up is used, for which, before the next start-up of the electric drive, first using the brake 6 obstructed shaft attached to

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the elastic element 4 from the side of the electric motor 1, then disconnect the rigid joint of this shaft and the actuator 3 "by disconnecting the coupling 5 and freeing the elastic element 4, after which, when the stored potential energy of the elastic element 4 is consumed for the preliminary acceleration of the actuator 3, the shaft, attached to the elastic element 4 from the side of the electric motor 1, brake and carry out all the actions in the same sequence as described above and refers to the first start.

The waveform portion a-th (Fig. 3) corresponds to the use of the potential energy of the elastic element 4 stored during the previous launch, for which the brake 6 is turned on and the coupling 5 is disconnected, making it possible to “straighten out” (the elastic element 4. As can be seen from the oscillogram rotating the moment Mu developed by the potential energy stored in the elastic element 4 allows acceleration of the actuator 3 to begin even before the drive motor 1 is turned on. In this section of the oscillogram, the torque Mu decreases I of as "crushes" elastic member, and the angular velocity of the shaft of the actuator increases.

At time point B (Fig. 2 and the charger with the clutch 2 turned off, the motor 1 is turned on, which is dispersed idle, its speed quickly increases to a value corresponding to the stable part of the mechanical characteristic. The plot of the oscillogram 5> -c corresponds to the length of time during which the motor 1 accelerates idle.

At the moment of time the brake 6 is disconnected and the coupling 2 is turned on. At the same time, the motor 1 begins to "tighten" the elastic element 4 again, its torque M ^ increases, thereby increasing the speed of the actuator and o_V the time point o4 speed ea 'engine and actuator gear ^ will be the same5

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mi, and then include the coupling 5 · At the same time, the elastic element is fixed in the "twisted" state, and the rigidity of the kinematic transmission sharply increases by a factor of 250 (for the considered case, the flexibility of the kinematic transmission is reduced from 10 ^ rad / Nm to 4 -10 ^-4 happy / N. m.).

Further acceleration of the drive to ₍ steady speed (part of the oscillogram 3rd) and its subsequent operation occur with increased rigidity of the kinematic transmission, i.e. with the coupling 5 turned on, through which the torque Mu is transmitted to the shaft of the actuator 3.

Figures 2 and 3 show the nature of the change during the start-up and acceleration of the drive torque of the elastic element Mu and the drive motor MD, as well as the torque moment M ^ transmitted to the actuator after the coupling sleeve 5 is turned on. C +, and the actuator ιαι ^,

'the way traveled by the executive, the mechanism, the power loss in the engine. gatele l i) as well as energy losses in the motor windings.

The acceleration time of the drive electric motor to a speed at which the slip becomes less critical, in this case less than 0.2 s (when the drive is started in a known manner with »0.55 s).

Energy losses in the motor windings during the acceleration of the drive. _

(6.1 kW. S, i.e., 45.5% less than when starting the drive in a known manner.

The total time of acceleration of the drive to steady speed in both cases remains almost the same 1.0 s.

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Claims (1)

Claim The method of controlling the electric drive, according to which the electric motor is started and accelerated and connected to an elastic element connected to the actuator, then the electric motor is stopped, disconnected from the elastic element and the actuator is restarted and accelerated and accelerated mechanism, characterized in that, in order to reduce energy losses during start-up and acceleration of the drive, as well as to reduce heating of the motor windings, acceleration of the motor is carried idle and when the EC *! the complementary mechanism of the motor rotation speed fixes the elastic element in the stressed state, storing potential energy, and after restarting and accelerating the electric motor, the executive mechanism is pre-accelerated using the stored potential energy of the elastic element and at the time when the elastic element completely releases its stored energy, connect the motor to the elastic element.