摘要 |
PURPOSE:To improve the utility efficiency of an ROM by writing a high output voltage pattern in the region of the ROM for the low output voltage which is not originally used. CONSTITUTION:In a digital frequency and voltage control type inverter control system, a variable frequency is obtained by a rate multiplier 102 and a variable output voltage is obtained by an ROM103. When the number of output frequency steps is less than 1/2 of the totally counted number of frequency control input bit number, only the lower significant bit is inputted as the voltage selection address of the ROM103 except the most significant bit of the frequency control input, and the voltage which corresponds to the output frequency when the most significant bit is selected in the voltage pattern area corresponding to less than the lowest output frequency to normally become vacant area. |