Measurement System Based On PC Of Starting Characterristics Of 3-Phase Induction Motor

The measurement of starting characteristics of 3-phase induction motor (SCo3PIM) is a very important subject. So much research has been made at the final ten years of nineteen-ninety. Many factories and lab developed some measuring devices for themselves. On the other hand, there are some devices for sales that are based on MCU including some functions, for user interface and output printing, but they are slow, inconvenient and unstable.Nowadays, with the appearance of the maturation of PC communication interface and all kinds of measurement system based on PC, the convenient, powerful, safe measurement system of SCo3PIM is strongly demand.This paper analyses the theory, algorithm and merit and faults of the measurement devices of SCo3PIM domestic and international and designs a system using MCU and PC based on the basic calculating formulas of electro mechanics. The MCU AT89C2051 samples data, displays status and transmits sampled data. The program of MCU uses co-operation of INTs and the idea of embedded designed.The program uses a SerialPort communication class written by PHD Remon Spekreijse.This class can easily carry out byte- transmission and block- transmission.The communication-baudrate can be easily set. You can use this class only through joining the class headfile and appliedfile to your project. In the headfile of the View class auto-created by Visual C++ ,you must add a message fuction: afx_msg LONG OnComm(the WPARAM ch, the LPARAM port), correspondingly, you must add a response fuction in the appliedfile of the View class: the OnComm(the WPARAM ch, the LPARAM port). In the response function ,you can get the data trasmitted by MCU.The program of the system in PC is programmed by Visual C++. The program can save the data trasmitted by MCU in files and can open these files to examine the data. Accelerating a motor to a speed, then cutting off the power of the motor, letting the motor speed down, through testing the speed and time of the motor at the period of speed drop in two different instances-free load and loading a known inertia moment to the motor, this program can measure the inertia moment of the rotor of a motor. When we know the inertia of the rotor of a motor, The program can draw the starting-curve of the motor through the data reflecting the start of the motor. These curves include torque- revolving speed curve and revolving speed-time curve.In addition ,the program can save the curve into bmp files and can open these files.After many times of measurement in different, we can see these system have the following merits: simple operation, accurate measurement, powerful function, kind interface and good expandability.