KGS type high performance DC speed regulator control board

I. Overview
   KGS type high performance DC speed control board has won the favor of many users with its compact structure and perfect functions. The board uses the large-scale integrated circuit TC787 to complete the trigger pulse formation of the thyristor in the main circuit. The board not only contains 6 trigger pulse forming units for three-phase full-control bridges, but also designed with single-phase half-bridge trigger pulses for controlling the excitation of DC motors. Forming unit, the board is also designed with overvoltage, overcurrent, underexcitation, phase loss, overspeed protection units, pulse power amplifier and isolation shaping circuit, and its output can directly trigger thyristor components with a capacity of 1650A or less. The entire control system adopts a single large board structure, which has the advantages of small size, reasonable design, convenient adjustment, reliable operation, and easy maintenance.

II. Main technical indicators
1. Input control voltage: two independent three-phase 16V (line voltage), 14V (line voltage);
2. Input current feedback signal range: 0゛10V, positive polarity;
 3. Input speed (or voltage) feedback signal range: 0゛12V, positive polarity;
 4. Input given control voltage range: 0゛10V, positive polarity;
 5. Input three-phase synchronous voltage amplitude: three-phase AC phase voltage 30V, 50Hz;
 6. With the difference of speed and voltage feedback signal, it can form speed and current double closed loop or voltage and current double closed loop speed regulation system;
 7. It has overcurrent, current cutoff, overvoltage (or overspeed), phase loss, phase error protection and alarm functions. The protection threshold is adjustable. After protection, it can seal the pulse and give a contact signal for breaking the main circuit (contact capacity 220V/1A or 380V/0.5A);
8. It can output 8 channels of trigger pulse signals that directly trigger the thyristor components below 1650A (6 channels are used to trigger 6 thyristors in the main rectifier bridge, and the other two channels are used to trigger the thyristors in the excitation circuit of the single-phase half-controlled bridge);
9. It can be used in a fixed excitation or adjustable excitation DC motor speed control system with three-phase full control or three-phase half-controlled main circuit, and can also be used in an AC speed control system with a three-phase AC voltage control main circuit;
 10. It can be controlled inside or outside the board;
 11. The board contains a given integration link, and the integration time is adjustable;
 12. The overall dimensions are length〜width〜height=327mm〜202mm〜30mm;
 13. The installation size is length〜width=311mm〜187mm, and the installation aperture is 4-φ4.5.

3. Matters needing attention
  
1. The function and adjustment method of each potentiometer
   There are 18 potentiometers in the    KGS DC speed control board. The functions and adjustment methods of each potentiometer are as follows:

  (1) Potentiometers RP16, RP17, RP18 are three-phase synchronous voltage amplitude adjustment potentiometers added to the three input terminals of TC787 pins 18, 2, and 1, which are adjusted clockwise and added to TC787 three The synchronous voltage amplitude of the three synchronous voltage input terminals is reduced, that is, the phase of the TC787 output trigger pulse increases with respect to the voltage lag angle between the anode and cathode of the thyristor corresponding to the main circuit; the synchronous voltage amplitude added to the three synchronous voltage input terminals of the TC787 is adjusted counterclockwise The value increases, that is, the phase of the TC787 output trigger pulse decreases with respect to the voltage lag angle between the anode and cathode of the thyristor corresponding to the main circuit.
  (2) RP6 and RP5 are potentiometers corresponding to the given integral rise time and fall time adjustment respectively. RP6 adjusts the rise time of the given integral clockwise to increase; adjusts the rise time of the given integral counterclockwise to decrease. RP5 adjusts the falling time of the given integral clockwise to increase; adjusts the falling time of the given integral counterclockwise to decrease.
  (3) RP7 is the adjusting potentiometer that the differencer outputs the highest voltage when the given voltage Ug=0. Adjust the output voltage of the differentiator clockwise to increase, and adjust the output voltage of the differentiator counterclockwise to decrease. Generally, the potentiometer has been adjusted before leaving the factory, and the user does not need to adjust it again. The best position of the potentiometer is when Ug=10V, under the condition of no feedback, α=0 degrees.
 (4) RP9 is a potentiometer for limiter adjustment when Ug=0 and α=150 degrees. Adjust the limit value clockwise to increase, and adjust the limit value counterclockwise to decrease.
 (5) RP10 is an overcurrent protection threshold adjustment potentiometer. Adjust the protection threshold clockwise to increase, and adjust the ground needle to decrease the protection threshold.
 (6) RP1 is an overspeed or overvoltage protection threshold adjustment potentiometer. Adjust the protection threshold clockwise to decrease, and adjust the protection threshold counterclockwise to increase.
 (7) RP19 is the current cut-off protection threshold adjustment potentiometer. Adjust the protection threshold clockwise to decrease, and adjust the protection threshold counterclockwise to increase.
 (8) RP11 is the under-excitation protection threshold adjustment potentiometer. Adjust the protection threshold clockwise to decrease, and adjust the protection threshold counterclockwise to increase.
 (9) RP2 is the given potentiometer on the board. The given voltage of the armature is adjusted clockwise to increase, and the given voltage of the armature is adjusted counterclockwise to decrease. When the user uses the off-board potentiometer to control, the potentiometer is useless. It is recommended to remove the potentiometer at this time.
 (10) RP15 is the setting potentiometer of excitation current. Adjust the excitation current clockwise to decrease, and adjust the excitation current counterclockwise to increase.
 (11) RP4 is the actual speed (or voltage) feedback value adjustment potentiometer. Adjust the actual speed (or voltage) clockwise to reduce the feedback value, and adjust the actual speed (or voltage) counterclockwise to increase the feedback value.
 (12) RP8 is an overcurrent protection threshold adjustment potentiometer for excitation current. Adjust the protection threshold clockwise to decrease, and adjust the protection threshold counterclockwise to increase.
 (13) RP14 is a sawtooth wave amplitude adjustment potentiometer for excitation trigger pulse forming unit. The amplitude of the sawtooth wave is adjusted clockwise to increase, and the amplitude of the sawtooth wave is adjusted counterclockwise to decrease. Generally, the potentiometer has been adjusted before leaving the factory, and the user does not need to adjust it again.
 (14) When RP16 is UgL=0, the maximum output voltage adjustment potentiometer of the differentiator of the excitation trigger pulse forming unit. Adjust the output voltage of the differentiator clockwise to decrease, and adjust the output voltage of the differentiator counterclockwise to increase. The correct position of the potentiometer is when UfL=0 and UgL』0, the phase of the trigger pulse output by TCA785 corresponds to the position where the AC voltage α=0 degree in the excitation circuit. Generally, the potentiometer has been adjusted before leaving the factory, and the user does not need to adjust it again.
 (15) RP12 is the maximum α angle adjustment potentiometer of the excitation circuit. Adjust the αmax angle clockwise to increase, and adjust the αmax angle counterclockwise to decrease. Generally, the potentiometer has been adjusted before leaving the factory, and the user does not need to adjust it again.
 (16) RP3 is an overspeed (or overvoltage) protection speed or voltage actual sampling value adjustment potentiometer. Adjust the sample value clockwise to decrease, and adjust the sample value counterclockwise to increase.
2. The role of each connector and external wiring
  (1) Connector S3 is a socket for control power supply and synchronous voltage input. In the connector, a1, b1, c1, a2, b2, and c2 are respectively connected to the two three-phase windings of the synchronous transformer with the power phase voltage of 9V and 8V, and the connectors a, b, and c are respectively connected to the corresponding synchronous power transformer For the three-phase with a mid-phase voltage of 30V (note that the phase sequence should not be connected wrong), its 300 terminal is connected to the neutral point of the three-phase synchronous voltage in the three-phase synchronous power transformer with star connection.
(2) G1, K1, G4, and K4 in the connector S1 are respectively connected to the gate and cathode of the two thyristors of the common cathode and common anode connection corresponding to the phase A voltage of the power grid in the three-phase rectifier circuit; and G3, K3, and G6 , K6 are respectively connected to the gate and cathode of the two thyristors corresponding to the common cathode and common anode of the B-phase voltage of the grid in the three-phase rectifier circuit; G5, K5 and G2, K2 are respectively connected to the corresponding C-phase voltage of the grid in the three-phase rectifier circuit The gate and cathode of the two thyristors are connected with a common cathode and a common anode.
 (3) G7, K7, G8, and K8 in the connector S2 are respectively connected to the gate and cathode of two thyristors in the adjustable excitation semi-controlled rectifier circuit corresponding to the positive and negative half cycles of the grid voltage. When the controlled motor is a fixed-excitation motor speed control system, the connector output is suspended.
(4) 201 and 227 in connector S6 are connected in the wire loop of the three-phase AC contactor that supplies power to the armature rectifier bridge, while 228 and 229 are connected in series to the single-phase AC contactor that supplies power to the excitation rectifier bridge. In the package loop.
 (5) The Iff in the connector S4 and the +V in -V, 300 and S4 are connected to the Hall element of the excitation current sampling in the excitation circuit (when the excitation circuit current sampling uses the Hall element). When the excitation circuit sampling element is an AC current transformer, Iff and 300 are connected to the excitation current sampling signal output after single-phase rectification, and 307 and 308 are connected to the reset button (both ends of the normally open contact).
(6) If the If in the connector S4 and +V, -V, 300 are connected to the sampled Hall element when the current sampling link in the armature circuit is the Hall element, and when the armature circuit current is sampled through the AC current transformer When, then If and 300 are connected to the three-phase rectified current signal output.

Four, application examples

The above structure of   KGS DC speed control board determines that it can be conveniently used for fixed excitation or adjustable excitation main circuit structure for three-phase full bridge, three-phase half-controlled bridge DC speed control system in. For the convenience of users, an example is now given to illustrate its application.
1. Used in adjustable excitation DC speed regulation system with three-phase full-control bridge as the main circuit
The DC motor of this type of system can be +220V and +440V. When the motor is +220V, the three phases A, B, and C come from the secondary side of the transformer, and when the motor is +440V, the three phases A, B, and C can be Directly from the three-phase grid can also come from the secondary side of the three-phase isolation transformer. In the figure, both the armature current and the excitation current are sampled by the Hall element, and the double closed loop of the speed current is selected. This type of system generally has a wider speed adjustment range. In the figure, the capacity of the Hall element can be selected according to the different rated capacity of the speed-regulated motor. The principle circuit of the KGS board used in this system is shown in Figure 1. In the figure, RM1 and RM2 are the measuring resistances of the two Hall elements, respectively. The wire wrap loops of JZ1 and JZ2 are connected by S in the KGS board. After the protection, the contact signals of the respective main circuits are disconnected, and the system runs in the overspeed protection mode.



Picture1 KGS board is used in the principle diagram of the adjustable excitation DC speed control system
2. Used in a fixed excitation system with a three-phase half-controlled main circuit

The principle circuit of the   KGS board used in this type of system is shown in Figure 2. In the figure, the armature circuit voltage is selected as the feedback to form a voltage and current double closed-loop system. The protection methods of the control panel are overvoltage, overcurrent, current cut-off, phase loss, and phase error protection. This type of system can be adjusted in the speed range and accuracy It is used in less demanding occasions and has the advantage of not needing to install a tachogenerator. In the figure, an AC side current transformer is selected to sample the current signal. Similarly, the fault signal contact derived from S in the KGS board is connected in series in the line package loop of the AC contactor that supplies power to the armature and the excitation loop. Therefore, such a system can be used in a DC speed control system with a rated voltage of +220V or +440V. in.

Figure 2 Principle circuit when KGS board is used in fixed excitation DC speed control system