The KCZ1 type low-power DC motor speed control board is suitable for the speed control of low-power DC motors. It contains voltage negative feedback (or speed negative feedback) and current negative feedback links, so The user can conveniently select the motor speed (or armature voltage) and armature current negative feedback to form a double closed-loop PI regulator, which controls the phase shift voltage of the thyristor trigger, and further converts the phase shift voltage into the trigger pulse of the corresponding conduction angle Drive high-power thyristor components to achieve the purpose of regulating and stabilizing the speed of the controlled DC motor. This board is improved on the basis of the original KJZ1 DC motor speed control board based on the opinions of users on the KJZ1 board. Compared with the KJZ1 board, it has the following advantages:
1. The board has a rectifier and voltage regulator device that can generate ¡À15V and +24V power supplies. In addition to the board itself, the ¡À15V power supply can also be used by users.
2. Replace the original KJ004 with TCA785, and replace the original KJ042 with 555 time base, so the external components are further reduced, the reliability is further improved, and the output pulse is a pulse train.
3. The board contains an over-current protection link. After protection, it not only blocks the user's output pulse, but also breaks the main circuit of the user's system. At the same time, it can realize the protection function according to the external fault signal (low level).
4. The board contains output pulse power amplifier and shaping link, which is most convenient for users.
5. The board contains four pulse power amplifier units, so the board can be used in single-phase bridge-type full-control or single-phase bridge-type half-control system or dual-half-wave controllable rectification system to meet the needs of different users.
Two. Main technical parameters
1. Input AC voltage: dual AC: 18V/0.5A, 50Hz;
2. Input phase shift control voltage Un: 0¡«-12V/0.1A;
3. Output DC voltage: ¡À15V/0.1A;
4. Input feedback voltage (or speed) value Vr: 0¡«+12V/0.1A;
5. Input feedback current amplitude Ir: AC (or DC) 0¡«10V/0.1A (or 0¡«+12V/0.1A);
6. Phase shift range: 0¡«170¡ã;
7. Speed ??stabilization accuracy: 1%;
8. Input pulse signal L amplitude <2V/0.1A;
9. Output four channels of trigger pulse high level amplitude: 10V/400mA;
10. Dimensions: length¡Áwidth¡Áheight=164mm¡Á147mm¡Á30mm;
11. Speed ??regulation ratio: 20:1;
12. The distance between the four mounting holes is ¦µ4.5, and the mounting size is length¡Áwidth=153mm¡Á134mm.
3. How to use KCZ1 board
The schematic diagram of the component layout of the main components in the KCZ1 board is shown in Figure 1. It can be seen from the figure that there are seven useful potentiometers inside, and there are three external leads Connectors.
The function and adjustment method of each potentiometer:
¡¡¡¡1, W1 is that the user uses the given potentiometer in the board as the output adjustment potentiometer at a given time. Generally, the user uses an external potentiometer to set it, so the potentiometer is often not used.
¡¡¡¡2. W2 is the feedback voltage (or speed feedback) amplitude adjustment potentiometer. Clockwise adjustment of the feedback amplitude decreases, and counterclockwise adjustment of the feedback amplitude increases.
¡¡ 3. W3 is the current feedback amplitude adjustment potentiometer. Clockwise adjusts the feedback value to decrease, and counterclockwise adjusts the feedback value to increase.
¡¡¡¡4. W4 is the output voltage adjustment potentiometer of the differentiator. When the given voltage Un is zero, W4 determines the highest voltage output by the differentiator. When Un is the maximum, adjusting W4 can make the output voltage of the differentiator zero, that is, when Un is At the maximum, when If and Vf are both zero, adjusting W4 so that the output pulse is exactly at ¦Á=0¡ã is the most suitable value for W4. At this time, the voltage of pin 11 of TCA785 is -0.7V¡«0V.
¡¡¡¡5. W5 is the current sampling signal maximum value adjustment potentiometer used for overcurrent protection. Clockwise adjusts the current sampling value for overcurrent protection to decrease, and counterclockwise adjusts the maximum value of current sampling signal for overcurrent protection to increase. When the current feedback is maximum, it is more appropriate to adjust W5 so that the midpoint voltage is 6V.
Figure 1 Component layout diagram of KCZ1 board
¡¡¡¡ 6. W6 overcurrent protection threshold adjustment potentiometer, clockwise adjustment of the overcurrent protection threshold increases, counterclockwise adjustment of the overcurrent protection threshold decreases.
¡¡¡¡7. W7 is the maximum limit adjustment potentiometer of the phase shift voltage. When Un=0, If=0, Vf=0, adjust W7 so that the output pulse is just at the position of the control angle ¦Á=180¡ã, which is the most suitable choice for W7 value. W7 adjusts counterclockwise ¦Ámax to decrease, and clockwise adjusts ¦Ámax to increase.
¡¡¡¡ 8. W8 is a sawtooth wave amplitude adjustment potentiometer. Clockwise adjusts the sawtooth wave amplitude to increase and counterclockwise to adjust the sawtooth wave amplitude to decrease.
The KCZ1 board has three connectors for external connection, and the external wiring method of each connector is as follows:
¡¡1. The 18V, D, and 18V in the connector S1 are respectively the secondary windings of a dual 18V AC transformer with a middle tap, and D is connected to the middle tap, which is the reference ground for the control board. And Un, -15V, D are respectively connected to the three terminals of a given potentiometer, it is recommended to connect -15V through a resistor with a resistance of 1K to an external given potential with a resistance of 5.6K (power 0.5W or 1W) The fixed end of the device, D is connected to the other fixed end, and Un is connected to the midpoint of the potentiometer, and the remaining If and D and Vf and D are connected to the current and speed (or voltage) feedback signals respectively. It should be noted that The feedback signals should all be positive polarity, +15V is an output DC power supply for users to use, L is the sealed pulse signal after an external fault, and the low level (<2V) is valid.
¡¡2. G1, K1¡«G4, K4 in the connector S2 are respectively connected to the gate cathodes of the four thyristors in the main circuit (when the main circuit is single-phase bridge full control), and the main circuit is a common cathode (or common anode) single-phase bridge In the case of a semi-controlled rectifier circuit, only G1, K1 and G3, K3 (or G2, K2 and G4, K4) can be used to trigger the two thyristors in the main circuit. When the main circuit is single-phase dual-half-wave controlled rectification , You can choose only G1, K1 and G2, K2 or G3, K3 and G4, K4 to trigger the two thyristors in the circuit. When the main circuit is single-phase half-wave controllable rectification, you can only choose G1, K1¡«G4 , Either way in K4 to trigger the thyristor.
¡¡3. Between A and B in the connector S3 is a normally closed contact, which is used to break the main circuit of the user system under fault conditions. The contact capacity is 220V/1A or 380V/0.5A.
Four. Application examples
The above structure of the KCZ1 board determines that it can be conveniently used in the main circuit for single-phase bridge-type full control, single-phase bridge-type half-control or single-phase half-wave controllable Rectification, single-phase dual-half-wave controllable rectification DC motor speed control system as the trigger and control board of the thyristor, for the convenience of users, two examples are given to illustrate its application.
1. It is used for the speed and current double closed-loop DC speed regulation system where the main circuit is a single-phase bridge fully-controlled rectifier circuit. The application of the KCZ1 board in this system is shown in Figure 2. In the figure, CT is a current transformer, and G is a speed measurement. generator.
Figure 2 KCZ1 board is used for the main circuit of single-phase bridge-type full-control rectifier speed current double closed-loop DC speed regulation system diagram
¡¡¡¡2. It is used in the voltage and current double closed-loop DC speed regulation system whose main circuit is single-phase double-half-wave controllable rectification. The application of KCZ1 board in this system is shown in Figure 3. In the figure, HLV is Hall voltage transformer, HLI It is a Hall current sensor.