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With the development of science and technology, the level of the electrical automation in the production process continues to improve, to become the focus of attention of the professionals choice for motor starting mode. Liquid resistor soft starting system plasticity is very good, and simple to operate, reliable operation, easy maintenance, low cost, and repeatedly starting the advantages, widely used in the fields of chemical industry, metallurgy, building materials and light industry. This paper through the analysis of the the liquid soft starter system, determine the design of the overall architecture. For the characteristics of the liquid soft start system and to achieve the basic functions, the model used Mitsubishi FX2N-64MR-001 programmable controller as the core of liquid soft-start control system control. And add a touch LCD display of information, so that the whole system is more convenient to use. For the liquid part of the hardware of the soft starting system, including the main circuit, control circuit, switch input and output circuits, human-computer interaction unit, in which the control circuit including signal detection circuit, V / F converter circuit, the signal generating circuit, multivibrator circuit, drive circuit, isolation circuitry and the like. Separate the various functional modules in the design, and finally combined, greatly reducing the hardware design cycle, and also provides a convenient debugging and maintenance of late. For the software part of the liquid soft start system, first designed the control flow of the whole system, the whole system is more complex, so according to the different functions of each part of the system to achieve the whole system is divided into several sub-modules, including the initialization module, sampling and testing The main program module, the automatic control module, manual control module, respectively, for programming. Block-design mode not only makes the entire software design ideas more clearly, and also to reduce the error rate of the program, and the debugging process also provides a lot of convenience to the operator to improve the maintainability and reuse rate for the entire program . In the control process of the the liquid soft starter system, this design uses PID control algorithm and fuzzy control algorithm alternately control the control algorithm, the two together, to make full use of the advantages of PID algorithm and fuzzy algorithm for segment control, resulting in Ideally, the static and dynamic characteristics. Finally Proteus software for V / F variation circuit simulation, during the simulation by changing the size of the input voltage Ui to obtain a different frequency waveform, and then calculate the corresponding frequency value, voltage frequency conversion made by these data FIG. Simulation using Matlab software, build a model, and enter the appropriate parameter values ??for the system as a whole, has been directly starter soft start simulation waveforms prove the liquid soft starter system is expected to be able to complete the requirements and purpose.
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