CONTROLLER AND CONTROL METHOD FOR BRUSHLESS MOTOR EMPLOYING SENSORLESS DETECTION OF COMMUTATING POSITION

摘要

PROBLEM TO BE SOLVED: To detect the commutating position accurately and continuously by comparing the current variation rate waveform of each stator coil with a predetermined threshold voltage thereby determining an active stator coil. ;SOLUTION: A motor 2 has four stator coils 4, 8, 12, 16 and a plurality of current sensors 42, 44, 46, 48 detect currents flowing through the stator coils 4, 8, 12, 16 and supply the current waveform thereof to a switch circuit 34. On the other hand, differentiation circuits 62-68 determine the current variation rate waveforms and comparators 72-78 compare respective current variation rate waveforms with a threshold voltage predetermined by a variable voltage reference level 36. Subsequently, a sample-and-hold module 38 detects an active stator coil. According to the method, a commutation point can be detected accurately.;COPYRIGHT: (C)1998,JPO