Abstract: An easily restarted brushless DC motor has a skeleton type stator core, a rotor core having permanent magnets arranged around it, and needs only one position sensor adapted to detect a rotational position of a rotor and only one stator coil. A controller is provided for switching over the polarity of the electrical power supplied to the stator coil in accordance with an output of the position sensor.

Abstract: A control device for brushless motor comprises an inverter (3), a control circuit (8) and a rotor position detecting circuit (9). In the rotor position detecting circuit (9), voltage induced in stator coils (U, V and W) due to rotation of a rotor (7) and neutral voltage at a virtual neutral point (25) are compared by comparators (CU, CV and CW) so that polarity changing points can be detected. The control circuit (8) controls the inverter (3) based on the above stated polarity changing points so as to control changeover of the modes for conducting to the stator coils (U, V and W). As a result, rotation of a brushless motor can be controlled without using Hall elements.