The Design Of The Electric Motor Velocity Modulation Control System

With the appearance of high-power switching devices，analog and digital ASIC and thedevelopment of control technology，enables the electric motor velocity modulation systemto obtain the rapid development. In electric motor velocity modulation system，thefrequency conversion velocity modulation is big because of its governor deflection, thecharacteristic is hard, the precision is high, in velocity modulation process stray losses, butwidespread application one velocity modulation way. This article research work launchesregarding the electric motor velocity modulation control system, Introduces PROFIBUSthe communication protocol the basic scope，have summarized in the motor controlsystem’s frequency conversion velocity modulation technology， take the frequencychanger as the foundation，have developed based on the PROFIBUS correspondencefrequency conversion velocity modulation system， explained this system hardwarecomposition and the related software development，and involves to the control system insome questions have made a more detailed analysis.Meanwhile, in this paper the working principle, motor speed control principle andbasic knowledge of PROFIBUS analyzed in detail. Also involves test line connections,test procedures and programming software and configuration design of specific process.Finally, this paper gives the motor speed control system bus-control process.The papers introduce PROFIBUS technology in application of the dingoes frequencycontrol which is controlled by S7-300PLC give the PROFIBUS configure，and alsointroduce the implement to control the frequency converter.Field bus technology is a hot topic among every country in the world. Digital controlsystem based on field bus is the mainstream of automatic control system in the21stcentury. PROFIBUS-DP is a kind of optimized high-speed economic communicationjunction, which specially designs for automatic control system and equipment scatterI/O and uses PROFIBUS-DP module to replace highly-priced24V or0—20mA parallelsignal wire. It can be used in high-speed data transmission in the distributed controlsystem. PROFIBUS-DP is mainly applied in field apparatus whose reaction time rangesfrom several seconds to several hundred seconds, data transmission rate is from9.6kbit to12Mbit per second, data capacity is as many as244byte every massage, transmissionmedia is STP or optical cable widely used in auto control system of buildingsautomation, hydro-plant management and industrial process. At present domestic-produced asynchronous motors mostly don’t havecommunication interface. Even some have, most of them are RS232or RS485serial buswhich are not suitable for industrial field bus control due to its features and set barriers torealize further networking development of the electric motor air fleet and management andcontrol all-in-one of enterprises and integrated automation. This paper introducescontrollers with PROFIBUS-DP bus interface, which can be used to solve the deficienciesof traditional electric motor intrasite commutations and realizes direct numerical control ofelectric motor to facilitate under stratum networking construction of enterprises integratedautomation and brings remarked economic benefits.Innovation point of the paper: At present domestic-produced asynchronous motorsmostly don’t have communication interface. The paper innovatively puts forward the ideaof using PROFIBUS-DP bus to design telecontrol communication interface circuit of ACmotor.