Characteristics and application of thyristor constant-current and constant-voltage module 1. IntroductionIn
modern industrial production, thyristor is widely used because of its mature technology, high current and high voltage. In the automatic control systems composed of thyristors, many of them are constant current controlled by current closed loop and constant voltage controlled by voltage closed loop. However, at present, most constant-current and constant-voltage thyristor devices and products are limited by sensors and control circuits, which are large in size, complex in structure, difficult to debug and low in control accuracy. Moreover, because the shunt and voltage divider are used for sampling, there is no isolation measure, and the electromagnetic interference of the control circuit is large, so it is difficult to interface with the computer. The application of thyristor constant current and voltage equipment is in a difficult state. However, the constant-current and constant-voltage equipment using thyristor has great application space because of its wide range of constant voltage (0 ~ several hundred volts) and constant current (0 ~ several hundred amperes). The constant current and constant voltage intelligent module produced by our company solves the contradiction between application and manufacture.
Compared with the traditional constant-current and constant-voltage equipment, the constant-current and constant-voltage intelligent module adopts linear Hall sensor, high-precision control circuit and modular production technology, which has the characteristics of complete isolation of control circuit from high voltage, high control precision, small volume and convenient use, and will be widely used.
2. Working principle
(1) Main working circuit
The main circuit constant voltage intelligent module is a three-phase fully controlled rectifier bridge composed of six thyristors. By changing the conduction angle of the control circuit, the DC voltage of 0-50V can be obtained.
(1) hall sensor is adopted.
Hall effect sensor is a new type of current and voltage sampling device. Its working principle is to convert current and voltage into voltage signals by using Hall effect of induced voltage generated by Hall element in magnetic field. Hall sensor has the advantages of high conversion coefficient, electrical isolation, fast response speed and good linearity, which is of great benefit to improve the performance of the whole machine. 2. Characteristics of control system
(1) Adopt linear Hall sensor to realize electrical isolation, improve the performance of the whole machine, make the set voltage (0-10V) have a good linear correspondence with the output voltage and current, and overcome the disadvantages of nonlinear phase shift angle and output voltage of thyristor.
(2) Two sets of independent circuits are used for voltage feedback and current feedback, which do not affect each other and can be automatically converted by external level.
(3) Multiple protection functions, making it safer and more convenient to use.
(4) Digital phase-shifting control circuit is adopted to make the trigger more accurate and reliable.
3. Main technical parameters and functions of constant current and constant voltage intelligent module
Due to the adoption of high-precision Hall sensor and precision amplifier circuit, the modular product shortens the signal transmission distance between the control circuit, the phase-shifting circuit and the main circuit, and has the characteristics of small interference, which makes the control accuracy of the constant-current and constant-voltage module higher, superior to other products with the same function.
(1) the high control accuracy is within the range of good linearity of thyristor control curve (constant voltage is 100V-350V, constant current is about 35%-75%I (the maximum set current)), the voltage stabilizing accuracy is 0.5%, the current stabilizing accuracy is within 1%, and within the range of poor linearity, the voltage stabilizing accuracy is not more than 1% and the current stabilizing accuracy is not more than 2%.
(2) Power grid adjustment rate: the power grid changes by 20%, and the output change (within the adjustment range) does not exceed 1%.
(3) High linearity corresponds. The 0-10V setting has a good linear relationship with the output current (voltage), and the nonlinearity is not more than 5%.
In addition to the function of constant current and voltage, this module also has the following functions:Multiple protection functions, such as overcurrent, overheat and open-phase protection, make the application of the module safer.Sampling signal output, Hall sensor sampling signal output, external current and voltage display.
The function of constant current and voltage is prohibited. If you are not satisfied with the internal constant current and voltage effect, you can connect the external control circuit and sample the signal directly with the sensor. 4. Application of Constant Current and Constant Voltage Module
Constant-voltage intelligent module has the characteristics of high control circuit precision, good balance, wide working voltage range, good current impact resistance, simple installation and use, high reliability, small size, maintenance-free, and miniaturization of power supply. It can be widely used in motor, generator excitation, DC screen (battery charging), laser power supply, magnetizing equipment, UPS power supply and other occasions. Modern foreign countries widely use "floating superposition" linear power supply.
The device is used for high-precision and high-power linear regulated power supply, which greatly reduces the power consumption of GTR, greatly improves the efficiency and reliability, and can adopt GTR with lower power, thus reducing the cost. Using constant current and constant voltage module not only improves the accuracy, but also greatly reduces the power supply volume.
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