Sensorless Speed Control of BLDC Motor

Brushles DC motor are one type of motors that are rapidly gaining the popularity and are penetrating in industrial applications, home appliances, automotive, consumer, medical etc. Because of there many advantages such as high efficiency ,silent operation, compact form ,reliability, low maintenance (due to the absence of brushess), long operating life, high speed ranges etc. for the proper commution of current in inverter the rotar position information is necessary, this information is usually provided by the mechanical position sensors mounted within the motor. however it is well known that these position sensors have many drawbacks therefore a sensor less control of BLDC motor is developed which eliminates the sensing equipment ,reduces the cost of motor and increases the reliability of the BLDC motor. In this paper the position information is obtained from the zero crossing detection of the back EMF which is also called as the terminal voltage sensing method which is the simplest ,method of detecting the back EMF zero crossing ,here the motor voltages are sensed and give to the lowpass filter whose output is give to the ZCD which determines the zero crossing of the back EMF waveform and ZCD generates the signal required for the controller to provide the pulses for the inverter operation the controller used is a high performance controller(DSPic30F4011) which as both the features of microcontroller and digital signal processor .The complete model is simulated in MATLAB/SIMULINK software. the proposed hardware and simulation program are found to be efficient and the results are promising