For proper commutation most 3-phase BLDC driver circuits rely either on a sensor based feedback or from an external 3-phase sync signal, contrary to this our present sensorless high power BLDC motor controller circuit does not depend on sensors or any external signals for operating the motor, rather very simply processes the back EMFs from the motor winding to produce the required powerful synchronized rotational effect on the motor.
So far in this website we have comprehensively learned regarding many BLDC motor controller using innovative state-of-the-art ICs, you can refer to these posts for an alternative view regarding the subject:
The following diagram shows the complete design layout of the proposed sensorless BLDC controller using back EMF as the triggering source.
The system looks pretty straightforward, you just have to solder the shown components in place and quickly start the BLDC operations. It is as simple as switching ON power and seeing the BLDC motor rotate with full efficiency.The controls are also very easy to understand and implement, the RUN/BRAKE switch enables the motor to continue running as long as the switch is in the OFF position, or not grounded, while the motor is instantly stopped as soon as the switch is toggled at the ground level.The POT R18 allows the user to control the speed of the motor linearly, simply by moving the pot knob across the specified range.
The biggest advantage of this 3-phase sensorless BLDC controller is that it does not require the messy sensor based feedbacks from the motor, neither depends on a 3-phase sync signal from the an external source. As can be witnessed in the above diagram, the feedback is achieved from the motor's main 3 phase operating wires via R8/R9/R10 into the designated pinouts of the IC.
This allows the controller to be used with all types of BLdC motors whether or not a sensor is available. If sensors are available from a BLDC, those can be ignored and the motor may be configured without the sensor wires, as indicated in the above diagram.
For further details and information you can go through the following datasheet of the IC: