| The measurement of starting characteristics for 3-phase induction motor (SC3PIM) is a very important subject. So many researches have been done at the 1990s'. Many factories and labs developed some measurement devices themselves. On the other hand, there are some devices for sales that are based on micro control unit (MCU) including some functions, such as user interface and output printing, but they are slow, inconvenient and unstable. Nowadays, with the appearance of the maturation of personal computer (PC) communication interface and all kinds of measurement system based on PC, the convenient, powerful, safe measurement system of SC3PIM is strongly demanded. This paper analyses the theory, algorithm and merits and faults of the measurement devices of SC3PIM from domestic and international, and designs a system using MCU and PC based on the basic calculating formulas of electrical machinery. The MCU AT89C2051 samples data, displays status and transmits sampled data. The program of MCU uses co-operation of interrupters (INTs) and the idea of embedded design. The software of the system in PC is programmed by C++ Builder, and organized the constructions by MDI. The following functions, real time sampling, data processing, curve plotting based on the parameters of measured motor and sampled data, curve printing, display configuration, are included. On the other hand, the moment of inertia of the measured motor can be got in two methods, which are calculation based on the model and measurement online. Therefore, the torque of the measured motor can be scaled. Moreover, the user can compare the different motor through observing the same kind of several curves in one window. After many times of measurement in different power and number of pole-pairs motors, we can see that this system has the following merits, such as simple operation, accurate measurement, powerful function, kind interface and good expandability. |
