The Study of Fuzzy Variable Frequency Control System for Constant Pressure

Author(s):  
Cong Tian ◽  
Chang Su ◽  
Weiping Zhao
2014 ◽  
Vol 971-973 ◽  
pp. 1828-1833
Author(s):  
Bo Zheng ◽  
Hong Zheng

At present the Space Vector Pulse Width Modulation (SVPWM) technique has been widely used in the variable frequency control system,but the technique will make the system produce higher harmonic components at the switching frequency integer multiple times,thus the harmonic produce the high frequency noise.In the face of this problem, this paper adopts double random SVPWM technique which is added two state Markov chain to effectively reduce the high frequency noise.The technique makes the harmonic components amplitude value of the output current reduced effectively in the inverter of the variable frequency control system,so that the more output current is more relatively evenly distributed in the wide frequency range,so as to minimize the electromagnetic noise.


2012 ◽  
Vol 442 ◽  
pp. 199-203 ◽  
Author(s):  
Liang Gui Peng ◽  
Yang Gao ◽  
Xian Ming Zhao ◽  
Di Wu ◽  
Zhong Ping Zhang ◽  
...  

With advanced high-strength steels and high value-added steels development, it is urgent to innovative run out table cooling line in hot strip mill with flexible cooling capacity to meet products metallurgical requirements of the cooling rate after rolling. The way to increase the cooling capacity is to improve the effect of heat exchange of water forced convection with hot strip. Then to raise the spraying pressure to penetrate the residual water and break the vapor inside it is the most feasible method. So, how to control the variable frequency device providing variable spraying pressure is the object of this study. Firstly, cooling after rolling process requirement under ultra fast cooling was analyzed; secondly, characteristic curves of centrifugal pump and water supply pipeline were tested; then inverter timing control, interlock control, security control and so on were studied. Since online application of the variable frequency control system, the water supply system has been running stably and reliably


2013 ◽  
Vol 694-697 ◽  
pp. 2172-2175
Author(s):  
Yi Wang Wang

The variable frequency speed control is one of the most important issues for fan filter unit (FFU) system. A novel digital variable frequency control system for FFU motors were proposed and developed to decrease running losses, and improve the speed control effect and accuracy. The system uses high-performance digital signal processor (DSP) TMS320F2812 as the control core, which adopts a dedicated motor pulse width modulation (PWM) control module to achieve the FFU motors real-time online digital variable frequency control. The composition and working principle of control system were illustrated, the hardware and software design were illustrated in detail. Finally, the experimental results on control system prototype were given, which confirm the effectiveness and validity of the control strategy, and demonstrate that the proposed method can achieve accurate variable frequency speed control of FFU motors.


2021 ◽  
Vol 11 (3) ◽  
pp. 964-972
Author(s):  
Qiuli Hui

In recent years, with the continuous improvement of medical treatment at home and abroad, computerized tomography (CT) technology has developed rapidly. The market competition at home and abroad is becoming increasingly fierce. The manufacturing cost of CT machines is highly valued by manufacturers. Reducing the manufacturing costs of CT machines is of great significance to medical equipment companies. The CT host is composed of a fixed control system and a rotation control system. Based on the analysis of the existing CT host system structure, this paper designs and implements a set of low-cost asynchronous variable-frequency rotation control systems based on the unchanged control interface of the existing main rotation servo control system, improving the market competitiveness of the product. Based on the constant structure of the rotating machine of the CT machine, the simulation analysis of asynchronous variable frequency control is carried out. A set of asynchronous variable frequency control design schemes and multi-stage speed curve control methods compatible with the original system structure are obtained. The verification and analysis of the functions of acceleration and deceleration control, rotation positioning, fault protection, electromagnetic radiation and other functions at the highest speed meet the system’s main performance requirements, such as acceleration and deceleration time at the highest speed, positioning accuracy, and speed stability. Through internal system verification, testing and clinical verification, the control system designed in this paper meets the design requirements. According to experimental data, the system is fully compatible with a running accuracy of 0.3%. The main performance indicators such as acceleration time and positioning accuracy have been improved. The acceleration time from static acceleration to the maximum speed of 0.39 seconds per revolution increases from 21 seconds to 19.9 seconds, and the positioning accuracy was improved from 0.3° to 0.24°. Finally, this study explores the diagnostic value of multislice spiral CT (MSCT) in ankle trauma.


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