| 摘要 |
PROBLEM TO BE SOLVED: To reduce a lower-order harmonic wave in PWM control of an inverter and to implement pulse count switching while reducing output voltage and line-to-line voltage variations and current variations.SOLUTION: A control section 10 of an inverter 4 includes: a modulation rate computing element 11; a pulse count determination section 13 for determining the number of pulses per half period; a switching pattern table 12 for storing a switching pattern which secures a minimum pulse width by reducing a lower-order harmonic wave of an output voltage, in accordance with a magnitude of a modulation rate for each pulse count; a pulse count switching section 14; and a gate generator 16. When the number of pulses from the pulse count determination section 13 is changed, the pulse count switching section 14 switches the switching patterns after waiting the timing when a voltage between output lines of the inverter 4 is not changed by a double switching voltage within a predetermined time, by providing a switching transition term. |
