Drive circuit for three=phase brushless DC motor e.g. for video cassette recorder or floppy disc drive

摘要

The drive circuit has a Hall sensor (40) providing a Hall signal (HS) dependent on the magnetic field strength of the rotor magnets, fed to a peak value detector (42), providing a peak value signal fed to a stepped voltage generator (44), providing the stepped voltage signals (Ustp,Vstp,Wstp) for each of the stator coils. Each of the stepped voltage signals has a period which is three times the period duration of the Hall signal and a phase which is offset by 120 or 240 degrees respectively from the other 2 stepped voltage signals.