| 摘要 |
PURPOSE:To suppress noise and torque ripple by resetting a high frequency counter upon matching of outputs from two counters, respectively, counting high and low frequency clock signals in synchronism with the rotation of motor and employing the matched result as an internal clock signal. CONSTITUTION:Position signals S1-S3 are fed from three Hall elements HE1-HE3 to comparing circuits 2-4 respectively in order to obtain rectangular wave signals S5-S7 having phase difference of 120 deg.. The signals S5-S7 are stored 12 and subsequently subjected to exclusive-OR operation 6 thus obtaining an ORed output signal S11 which varies at all varying points of the signals S5-S7. A high frequency clock signal is created 40 from the signal S11 and fed through a counter 11 to the memory 12. When the count of the signals S5-S7 matches with the count of the counter 11, the counter 11 is reset and thus matched count is employed as an internal clock signal. According to the invention, noise and torque ripple are suppressed. |
