| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for determining a PWM control duty which can further reduce a noise level than techniques for slight variations in a communication frequency. <P>SOLUTION: When slightly varying the duty of a PWM signal output to a drive circuit around a command value such that an average in a predetermined period matches the command value, a control IC 63 stores in a database 69 in a PC 68 data reflecting level measurements of noise components caused by actual supply to the PWM signal to the drive circuit along with modes of variation of the duty. By reference to such data stored in the database 69, the control IC 63 determines a mode of variation of the PWM duty to reduce a noise level of a frequency band to be suppressed in accordance with given operating environment and operating conditions. <P>COPYRIGHT: (C)2012,JPO&INPIT |
