Patent ID: 8471511
Filing Date: 2013-06-25
Classification: H02P

Abstract:
1. A brushless motor control device comprising: a voltage application unit configured to cause each pair of switching elements connected to corresponding windings of a plurality of phases to apply a voltage to the corresponding windings of the phases in order to flow an electric current into the corresponding windings to generate a revolving magnetic field with a permanent magnet to rotate a magneto rotor of a brushless motor; an energization period derivation unit configured to detect rotation of the magneto rotor and to derive an energization period of the windings to generate the revolving magnetic field; a PWM signal generation unit configured to: a detection period specifying unit configured to specify a detection period of the electric current flowing into the windings connected to the switching elements, which are presently switched and deactivated, by a time period, which is from a time point in advance of an edge of the PWM signal by a predetermined period to the edge, the edge being caused when the PWM signal changes to a different level to switch to deactivate the switching elements to control an electric current supplied to the windings; wherein the PWM signal generation unit is further configured to generate the PWM signal for switching activation and deactivation of the switching elements according to a comparison result between a count value, which is increased and decreased by count up and countdown repeatedly implemented in a predetermined range, and a first threshold, which is determined according to the control signal, the detection period specifying unit is further configured to, the detection period specifying unit is further configured to,