SU849400A1 - Reversible thyristorized electric drive with field reversal - Google Patents

Description

The invention relates to electrical engineering and can be used to control the speed of a DC motor.

Known dual-zone valve actuator with reverse motor field, containing a non-reversible thyristor anchor transducer, a reverse thyristor 'exciter with pulse-phase control systems, a DC motor of independent excitation, tachogenerator ”speed and EMF motor speed controllers, speed and excitation current regulators, block _J5 logic of separate control of the pathogen, in which the reverse and braking of the motor is carried out by changing the direction of the excitation current, £ 1 3. '20

The disadvantages of this electric drive are the complexity, reduced reliability and the difficulty of obtaining a wide range of speed control.

Also known is a reversible thyristor electric drive with a field reversal, comprising a direct current motor with an independent excitation winding, connected to a non-reversible armature converter and re ~. a versatile exciter with pulse-phase control nodes • thyristors, a speed controller, to the input of which a frequency adjuster and a tachogenerator are connected, and the output through the inverter and key or directly through the key is connected to the input of the pulse-phase control node of the armature converter, the current limiting unit on transistors the inputs X of which are connected to the master and the motor armature current sensor, an excitation current regulator, the inputs of which are connected to the master and the motor excitation current sensor, and the output to the input block logic separate control of the pathogen, as well as through the inverter and the key or through 3 849 400 'directly through the key - to the input of the node of the pulse-phase control of the pathogen, the sensor and the emf of the motor, zero-organ connected between the output of the frequency regulator ₅ and the excitation current generator, the engine shutdown unit, the outputs of the logic unit being connected to the control inputs of the keys G2].

The disadvantage of this technical solution is the low speed, the presence of overshoot of the motor EMF in transient conditions.

The purpose of the invention is to improve the dynamic characteristics of electric drive 15.

This goal is achieved by the fact that in the well-known reversible thyristor electric drive with a field reversal, two additional 20 isolating and two blocking diodes, an inverter, two parallel-connected transistors connected by collectors with the input of the pulse-phase control unit of exciters, 25 and a control body are additionally introduced , while the collectors of the transistors of the current limiting node are connected to the output of the speed controller via decoupling diodes, and the corresponding inputs of these transistors directly and through invert OP and blocking diodes are connected to the output of the governing body, the inputs of which are connected to the logic unit and to the output 35 of the engine shutdown unit, the input of one of the parallel-connected transistors connected to the inverter output, and the input of the second to the master and EMF sensor. 40

The drawing shows a diagram of an electric drive. ...

: B; in this: -electric drive, the speed reference unit 1 and the tachogenerator ₄₅ 2 are connected to the input of the speed controller 3 (controller 3 can be a PI or PID controller) ·. Controller output 3 is connected via the inverter 4 and the key 5 or θ ₅ directly through the switch 6 to the input node pulse-phase control 7 anchor converter 8. anchor converter 8 is connected through 9. The motor armature ₅₅ di- ode 10 and 11 to the output of the regulator 3 a current limiting unit 12 is connected on transistors 13, 14 of different polar conductivity, the bases of which are connected to the armature current detector 15 and directly through the inverter 16 and diodes 17, 18c by the control body 19. The motor EMF limitation unit contains an EMF adjuster 20, input resistors 21- 23 tray the resistors 24, 25 and the resistor 26. The outputs of the current sensor of the armature 27 connected to the input of current transformers 28 are connected to the corresponding inputs of the node 12. The base of the transistor 24 is connected to the output of the EMF sensor of the armature 29 and to the EMF setter 20. The collectors of transistors 24 and 25 are connected to the input of the node 30 of the pulse-phase control of the exciter, the outputs of which are connected via keys 31 and 32 to the thyristor exciter 33, which feeds the excitation winding 34 of the motor, in the circuit of which the excitation current sensor 35 is straight. The input of the reversible null organ 36, the output of which is connected to the drive 37 of the excitation current, can be connected either to the output of the controller 3 (Fig. 1), or through the corresponding nonlinear links to the speed controller 1 and the tachogenerator 2. The inputs of the drive current controller 38 are connected to the setter 37 and the excitation current sensor 35, and the output through the inverter 39 and the key 40 or the key 41 and the resistor 26 with the input of the node 30. The inputs of the control body 19 are connected to the output of the logic unit 42 and to the output of the stop unit of the motor 43 connected via relay contacts to the niy B and N to the source of positive voltage. The inputs of the logic unit 42 are connected to the thyristor exciter 33 and to the output of the excitation current regulator. The outputs of the logic block 42 are connected to the control inputs of the keys 5, 6, 31, 32, 40, 41.

The electric drive operates as follows.

1. Start at rated speed.

When one of the direction switches Forward or Backward (V or n) is turned on, the input voltage is supplied to the inputs of controller 3 and nullorgan 36. In addition, a signal is received at the input of the stop unit of the engine 43, which acts through the governing body 19 on the current limiting unit 12. At the same time, the output of controller 3 is unblocked and translation is allowed

849400 6 control pulses in both nodes of the pulse-phase control. 7 and 30 with a maximum control angle otmcix · The polarity of the control signal determines the response of the logic unit ₅ 42 in the Forward or Backward directions, the logic unit closes the key 5 or 6 at the output of the regulator 3, keys 41 or 42 at the output of the excitation current regulator and a key 3-1 or 32, supplying control pulses to one of the sets of thyristors of the exciter 33. The excitation current and voltage at the motor armature increase to nominal values and the motor accelerates to is nominal noy speed. The value of the output voltage of the EMF sensor of the armature 29 in this zone is less than the voltage of the setpoint EMF 20, the transistor 24 is closed and does not affect the operation of the electric drive. In this case, the excitation current has a nominal value, and the engine speed is controlled by changing the voltage of the armature of the motor 9. The armature current during transient conditions is limited at the level determined by the setpoint 15.

When starting at maximum speed 30, when the nominal speed is reached, the signal from the sensor 29 becomes equal to the signal of the emf adjuster 20 and the transistor 24 starts to open, reducing the input voltage of the node 30, and thereby reducing the motor excitation current. The frequency of the motor 9 increases and its regulation in the second zone is carried out at a constant EMF of the motor (according to the principle of field weakening).

2. Reverse from maximum speed to maximum. ₄₅ '

When reversed, the Forward contact opens and the Back contact closes. The signal at the output of the regulator 3 changes sign and through the node 7 locks the anchor converter. Me- etsya mark ₅₀ and the output zero-body 36, which leads through the regulator 38 to the reversal of the excitation current. At the moment of switching unit 42 to the control logic 19 with the body ₅₅ Bloch ka logic 42 receives a positive pulse, which locks the assembly 12 through the controller 3. Thereby permitted work channel regulation of stresses, anchor only after the flow through zero. After a time delay of block 42, the armature voltage control channel opens. Under the influence of the armature current and flow, the motor accelerates in the first zone due to an increase in the armature voltage. Upon reaching the nominal speed of the engine 9, its further increase occurs due to the weakening of the excitation flow.

The proposed device does not require reverse feedback on the motor EMF, since feedback is used on the motor EMF of a unipolar sign. The exception of the feedback switch with a nullorgan and the replacement of the regulator with a transistor - an almost inertia-free element can simplify the electric drive and increase reliability.

The exclusion of inertia in the regulation of EMF eliminates the overshoot of the motor EMF and improves performance when working with a weakened field. For a valve electric drive using a dual-circuit system subordinate to regulation, there are difficulties with optimizing the dynamics due to the presence of two current modes: continuous and intermittent.

For a single-circuit valve actuator with a current-limiting unit, there is no such problem, and it is simpler. In addition, the current-limiting unit 12, in addition to limiting the armature current in the transition modes at a given level, together with a specially introduced control body 19, provides zero initial flow conditions and, as a result, a smooth start in both directions of rotation and absence at a zero reference signal. The control body 19 provides a positive output signal in the presence of a driving signal and a negative signal in the absence of a driving signal.

Claims (1)

1. USSR Author's Certificate No. 601794, cd. H 02 p 5/06, 1978 .. 2, USSR Copyright Certificate No. 2462631/07, cl. H 02 P 5/06, 1978.