INVERTER

摘要

PURPOSE:To reduce the percentage of a higher harmonic contained by a method wherein a switching element for connecting the contact point, where two switching elements are connected together in series between both the terminals of a power source, to the neutral point of the power source in an invertor. CONSTITUTION:DC power sources 10, 11 are connected together in series to form one power source, while the contact point where two sources are connected functions as the neutral point O of the power source. A smoothing capacitor 12 and a 3-phase bridge type switching circuit 13 are connected between the power sources. Each of the output terminals U-W of the switching circuit 13 is connected to a potentially neutral point O through switching transistors Tr13, Tr14, Tr23, Tr24, Tr33, Tr34. Each transistor of the switching circuit 13 is turned on, for instance, in the PWM method to obtain a 3-phase AC output at the output terminals U-W. In this case, when changing-over the output terminal from one power source terminal to the other, the terminal is connected to the neutral point O of the power source once.