| With the development of relevant technologies, people make their choices to comfortable air condition systems to instead the traditional ventilation equipment. Constant air-flow control is a new method ,when the pipe resistance has changed,this method controls the rotate speed to make the defferent air-flow constant. New type air-condition system with this method is fast developing.This paper introduces characteristics and performances of motor and pipe system first,then combines Bernouli equation to find the point of stabilized working of motor. Then introduce a new method of constant air-flow control from presenting the pipe resistance ,which includes along resistance and local resistance. Next we design and experiment a motor control system using the new method of constant air-flow, which uses MC68HC908MR8 that Freescale corporation designs for motor control ,which has a power factor correcting (PFC) model . The result of the system experiment shows the system is correct, and makes the constant air-flow. At last use VB 6.0 to programme the running software to achieve long-distance control with Modbus protocol. |
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