Simulation Research And Protection System Of 3kW Brushless Motor

Using traditional motor to control the transformer fan exists some defects, like a big power consumption, noise, low control precision and etc. So a new motor to replace the traditional motor is needed. Brushless DC Motor (BLDCM, hereinafter referred to as the motor) is not only overcame many drawbacks of traditional AC/DC motor, but also balanced their advantages. So this paper use BLDCM as the new device to control the transformer fan. But in practical application, the motor may be broke down by some faults, such as over voltage or over current. These malfunctions will bring great influence to the normal operation of the motor. Setting all these protection circuit and control circuit into the motor, not only expand it’s volume, but also increase the cost. Therefore, to design a protection system with high integration is very necessary.Firstly, by analyzing the basic structure and working principle of BLDCM, built the motor’s mathematical model. Based on this, using Matlab established the BLDCM’s model, both its working condition and fault condition. Comparing the waveforms, analyzed the changes when faults occurred.Then, according to the actual application of BLDCM, chosed TMS320F2812 as the main control chip, IR2130 as motor driver chip, and used high-precision hall current sensor as current sampling device. Combined with the function of these chips set the protection scheme, including the protecting circuits for over-current, over/under voltage, over temperature and the IGBT protection. At the same time, isolating circuit and the power-switching circuit also be designed in order to ensure the stable operation of the circuit.Finally, designed the software part of this system, and emphatically introduced the interrupt program for motor protection.