Circuit and method for sensorless control of a permanent magnet brushless motor during start-up

A system for controlling motor switching in a sensorless BLDG motor having a set of three stator windings, the system comprising:

• a controller unit comprising a control signal generator, a memory device, a processing unit, a signal acquisition device, and an analog-to-digital converter;
• a power stage having a plurality of switches, wherein the power stage receives a control signal from the control signal generator and a power signal from a power source, wherein the power stage drives two windings of the set of three stator windings and leaves one stator of the three stator windings undriven;
• wherein the processing unit acquires a demodulated measured voltage on the undriven winding;
• and
• wherein the processing unit communicates with the power stage to change which two windings of the three stator windings are driven when the demodulated measured voltage surpasses a threshold.