Drive circuit for a brushless direct-current motor

摘要

A drive circuit for a brushless direct-current motor, particularly a fan motor, which permits a flexible control or regulation of the power delivered to the direct-current motor depending on a desired or reference value. The drive circuit consists of power output stages which are supplied via a rectifier circuit direct from the a.c. supply, while the control of the power output stages is effected by a special control circuit. This control circuit is supplied via an auxiliary supply part from the a.c. supply. The control circuit delivers ramp-shaped output pluses each driving a control pulse for the motor current which comprises within each commutation phase a pulse that can vary from a symmetrical triangular form to a trapezoidal form. The driving circuit includes a restart circuit which supplies a separate supply voltage to an intermediate drive stage in a fashion which becomes intermittent if the motor is overloaded or blocked.