Using ADC or Comparator Peripheral for BEMF Detection

This MultiMotor series application note demonstrates the sensorless block commutation of a BLDC motor with Zilog’s Z32F128 ARM Cortex M3 architecture which is specifically designed to meet challenging design demands. This application note also discusses the theory of block commutation for a BLDC motor and the method by which the back electromotive force (BEMF) is detected for this type of motor control. The BEMF can be detected by using either a three-channel ADC module or three comparators to monitor each phase for the BEMF zero crossing.

This application note addresses the implementation of both methods for BEMF detection. For convenience and ease of implementation, a BLDC-type 24 V/30 W motor capable of running up to 3200 RPM is included in the demonstration kit.