| 摘要 |
PURPOSE:To form the brushless motor, which has excellent efficiency and corresponds to energy conservation, by a method wherein field-system magnetic-field distribution is detected, the magnitude of armature coil conduction currents is changed in conformity with the state of the distribution, and the ratio of torque to loss is kept approximately constant. CONSTITUTION:The intensity of a magnetic field with the revolution of a rotor 1 detected by means of a Hall element 6 and signals displaying the direction are inputted to a changeover control circuit 4 and a pulse width modulation circuit 7. The pulse width modulation circuit 7 is operated by detecting signals from the Hall element 6, and outputs pulse signals P, pulse width thereof changes in response to the intensity of a field-system magnetic-field by means of the rotor 1 and which have fixed frequency, to the changeover control circuit 4 while outputting signals S changing over a switch circuit 8 when the speed of revolution of the rotor 1 reduces from predetermined value. A changeover switch circuit 3 is turned ON/OFF by control signals from the changeover control circuit 4, and controls the quantity of conduction of the conduction currents of an armature coil 2 and the direction. |
