Sensorless BLDC control using BEMF and ZCP

The aim of the project is to control a BLDC motor using a sensorless control method: back EMF measurments and zero crossing point detection. Applying a six step commutation method each phase conducts for 120° electrical degrees, thus only two phases conduct current and the third one is used for BEMF/ZCP detection. Using three resistors, a voltage divider and a filter it's a feasible way to rebuild the virtual neutral point (because I don't have access to the center neutral point of the motor).

The BLDC used is a hoverboard motor (36V, 350W) and the main controller is a STM32F4 board.