| 摘要 |
PURPOSE:To provide an inverter outputting AC three-phase voltage through PWM control wherein uncontrollable region is eliminated by ensuring minimum ON pulse width and outputting a smooth sine wave voltage over the entire line voltage region. CONSTITUTION:The three-phase inverter outputting a voltage corresponding to a voltage reference for each phase through PWM control is provided with means 2 for determining any one of normal mode, rectangular mode, or zero correction mode based on the magnitude and the polarity of each of three-phase voltage references. The controller is further provided with means 3 for outputting the voltage reference as it is upon determination of normal mode whereas fixing the voltage reference for one phase at a predetermined level and correcting the voltage references for other phases such that the original line voltage is sustained according to a scheduled algorism upon determination of rectangular mode or zero correction mode. According to the constitution, minimum ON pulse width is ensured and a smooth sine wave voltage can be outputted over the entire three-phase output voltage region. |
