SU767830A1 - Device for controlling speed of data carrier in magnetic recording apparatus - Google Patents

Description

braking modes when regulating the speed down and resetting the load, especially at the lower limit of regulation, determines the presence of an area of intermittent currents, which is characterized by low rigidity of mechanical characteristics and limited accuracy characteristics of the device. In addition, with large dynamic effects on the drive, such as during different operating conditions, causing an increase in load, a significant drop in power occurs at the current controller, which increases the switching capacity and reduces the overload capacity of the device.

The purpose of the invention is to improve: the operation of the device with a wide range of disturbing dynamic effects and reducing the time of transient processes.

The goal is achieved by introducing a voltage limiter connected in parallel to the current controller and a dynamic braking unit connected between the output and power amplifiers and the yo motor of the electric motor. Fig. 1 is a block diagram of a device for controlling speed in the magnetic recording apparatus of Fig. 2, a voltage diagram at various points of the device. ,

The device comprises a reference frequency generator 1, the output of which is connected to one of the inputs of the comparison circuit 2, to the other 1y input of which the speed sensor 3 is connected. The output of the comparison circuit is connected to the input of power amplifier 4. The output of the POWER amplifier 4 is connected to the inputs of the current regulator 5, block b. a limiter, an electrolytic capacitor 7, and a dynamic braking unit 8, the outputs of which are connected to the control input of the driving motor 9, kinematically connected with the driving roller 10, coupled to the information carrier 11. The output of the engine 9 is connected to the output of the dynamic braking unit 8.

The diagram shows the voltage from the output of the reference frequency generator, the voltage from the speed sensor,; voltage at the output of the comparison; the total voltage on the engine 9 and the capacitor 7, the voltage on the capacitor 7 (controller 5 oka), the voltage on the engine 9.

The device works as follows.

The signal of the reference frequency generator 1 and the signal of the speed sensor 3, proportional to the rotational speed of the engine 9 (Fig. 1), are received in the comparison circuit 2, where they are compared in phase (Fig. 2, a, b, b) and voltage proportional to the difference phases.

through the power amplifier 4 and the regulator 5 connected in parallel, the electrolytic capacitor 7 and the voltage level limiter is supplied to the motor 9, i.e. The motor is supplied with a voltage in the form of pulses with a variable duty cycle (Fig. 2, e).

The voltage on the motor is equal to the difference between the supply voltage

Q and the voltage drop across the current controller 5 (Fig. 2, g, 3, e) (the voltage drop on the power amplifier 4 can be neglected).

With an increase in the load on the master drive, the current of the 5-motor stalling increases and the voltage drop across the current regulator 5 also increases (times t - t of Fig. 2e), while the amplitude of the voltage pulse on the motor 9 decreases (Fig. 2, e).

An increase in the voltage drop occurs until the voltage stabilizes and with a further increase in the current, the magnitude of the decrease in voltage across the current regulator is limited and remains constant, due to which the decrease in the amplitude of the voltage pulse on the motor ceases (Fig. 2, moment ti- 45) and thus, the drive overload method increases and transient time decreases.

Without a level limiter, an increase in the load current causes a significant voltage drop on the current regulator 5 (as indicated by the dotted line in Fig. 2.1,1, at times -if) and the dynamic characteristics of the device deteriorate.

Magnitude limit the voltage level is chosen based on

specific requirements for the drive.

Dynamic braking unit 8 provides for the creation of a circuit for the passage of a braking current at the moment when there is no impulse on the motor. This process takes place as follows: the electrolytic capacitor 7 is charged to the magnitude of the voltage drop across the controller 5

50 current, and due to significant

capacitor capacitance (on the order of 2000 µf, the voltage is constant, i.e. the pulses are smoothed.,

At the time of the absence of a pulse, the voltage of the motor on the engine is discharged by a capacitor 7, which creates a brake current I., which is directed towards the working current Tr.

The discharge occurs in the following circuit 60: the plus plate of the capacitor 7 is the dynamic braking unit .8, the engine 9 is the negative plate of the capacitor 7, i.e. the discharge current creates a mode of inhibition by counter-turning on (figure 2, e, curve 1-2 - the dotted line shows the curve in the absence of block 8 of inhibition).

With a decrease in the load, when the pulse becomes short (Fig. 2.6, moment ti-t) f, the discharge current of the capacitor, creating a deceleration mode, prevents the occurrence of an intermittent 1X current mode, and the smaller the heat capacity of the pulse, the longer the time for discharge and the greater the discharge current flows. Providing engine braking, by / learn the continuity of current at minimum loads and minimum speeds.

Thus, the inclusion of a voltage level limiter, by which the upper limit of the voltage drop across the current controller is limited and the activation of the dynamic braking unit preventing the occurrence of intermittent currents and reducing the current oscillations, allowed the device to operate under wide dynamic effects associated with for example, with different operating conditions and increase the device overload capacity by 3 times, reduce the time of transients, reducing the start time by 20% , increase the accuracy of the device, reducing the coefficient of oscillation of the instantaneous speed of movement of the carrier, information on. 30%, to increase the stability of the control system, especially at the lower limit, which makes it possible to drive the data carrier without a gearbox directly by the engine shaft at speeds up to fractions of a unit of revolutions per minute with the required accuracy.

Claims (2)

Invention Formula An apparatus for controlling the speed of movement of a storage medium in a magnetic recording apparatus, comprising a reference frequency generator to and speed sensor connected to The inputs of the comparison circuit, the output of which is connected through a serially connected power amplifier and current regulator to a controllable input, drive a 5tisro electric motor, and an electrolytic capacitor connected in parallel to the current regulator, which is designed to improve the operation of the device with a wide The 2Q range of disturbing dynamic effects, increasing its accuracy and reducing transient time, introduced a voltage limiter connected in parallel to the current controller, and a dynamic braking unit connected between the output of the power amplifier and the input of the aforementioned electric motor. Sources of information taken into account in the examination 30 1. Khrushchev V.V. Electric micromachines of automatic devices. L., Energie, 1976, p. 164-166. 2. USSR author's certificate in application number 2496748 / 18-24, 35 cl. C 11 V 15/46, 1977 (prototype).