| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a PWM inverter for controlling from output voltage 0 to an output voltage region of maximum voltage utilization rate continuously by combining a plurality of PWM mode in which a means for preventing disturbance of output current even during a transient time, e.g. high speed repowering time, is provided. <P>SOLUTION: A PWM mode for controlling a high output voltage region includes one kind of asynchronous PWM mode, i.e. an asynchronous overmodulation mode 1, and a synchronous PWM mode 2 and a means 3 selects one pulse pattern depending on the basic frequency of an output voltage and an output voltage command. When the basic frequency is lower than a specified value, pulse pattern S2 of synchronous PWM mode is selected and the output voltage is stabilized during normal acceleration/deceleration. When the basic frequency is higher than the specified value, pulse pattern S1 of asynchronous overmodulation mode is selected and switching of PWM mode is eliminated thus preventing bouncing of the output current. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
