| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve a two-phase modulating PWM-controlled inverter apparatus for controlling a phase difference using a constitution simpler than a constitution for detecting the phase difference from an AC current. <P>SOLUTION: A DC current detecting amplifier 6 detects a DC current flowing in an inverter circuit 2 at the upper or lower limit of a carrier with a predetermined PWM carrier period. A phase difference detector 8 detects the phase difference between an AC voltage and the AC current on the basis of the detected DC current. A PI calculator 11 calculates a duty reference value in response to an error between the detected AC voltage/current phase difference information and target phase difference information. A PWM creator 15 calculates a two-phase modulating PWM signal on the basis of sinusoidal wave data corresponding to a rotation speed of a motor and the duty reference value, and outputs the PWM signal to the inverter circuit 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
