Motor drive circuit
View Patent ↗A motor drive circuit includes: an advance angle setting correcting device having a correction reference cycle according to a reference advance angle count value, in which a correction amount is calculated as a ratio of the correction reference cycle to a cycle of a detection signal indicating a detected frequency proportional to a motor rotation speed, and in which an advance angle setting signal is obtained by multiplying the correction amount by a proportionality factor; and an advance angle setting device in which the advance angle correction value is added to the reference advance angle count value thereby outputting an advance angle setting signal, wherein a drive command signal containing a rotation speed information based on a target rotation speed is externally fed, the motor rotation speed is variably controlled in response to the drive command signal, and the detection signal is fed from a rotation speed detecting device.
1. A motor drive circuit comprising:
an advance angle setting correcting device which has a correction reference cycle predetermined according to a reference advance angle count value, in which a correction amount is calculated as a ratio of the correction reference cycle to a cycle of a detection signal indicating a detected frequency proportional to a rotation speed of a motor, and in which an advance angle setting signal is obtained in such a manner that the correction amount is multiplied by a proportionality factor; and
an advance angle setting device in which the advance angle correction value is added to the reference advance angle count value thereby outputting an advance angle setting signal,
wherein a drive command signal containing a rotation speed information based on a target rotation speed is fed to the motor drive circuit from outside, the rotation speed of the motor is variably controlled in response to the drive command signal, and wherein the detection signal indicating a detected frequency proportional to the rotation speed of the motor is fed to the motor drive circuit from a rotation speed detecting device attached to the motor.
2. A motor drive circuit according to claim 1 , further comprising a cycle detecting counter to output a detection cycle count value corresponding to a cycle of the detection signal calculated based on a reference clock, wherein the advance angle setting correcting device has a correction reference count value corresponding to the correction reference cycle and comprises a division device to divide the correction reference count value by the detection cycle count value thereby calculating the correction amount.
3. A motor drive circuit according to claim 1 , wherein the advance angle setting correcting device has a plurality of the correction reference cycles.
4. A motor drive circuit according to claim 1 , wherein the rotation speed information contained in the drive command signal is one of a voltage command signal corresponding to the target rotation speed and a PWM duty command signal.
5. A motor drive circuit according to claim 2 , wherein the advance angle setting correcting device has a plurality of the correction reference cycles.
6. A motor drive circuit according to claim 2 , wherein the rotation speed information contained in the drive command signal is one of a voltage command signal corresponding to the target rotation speed and a PWM duty command signal.
7. A motor drive circuit according to claim 3 , wherein the rotation speed information contained in the drive command signal is one of a voltage command signal corresponding to the target rotation speed and a PWM duty command signal.
8. A motor drive circuit according to claim 5 , wherein the rotation speed information contained in the drive command signal is one of a voltage command signal corresponding to the target rotation speed and a PWM duty command signal.