| 摘要 |
PURPOSE:To reduce a snubber loss by directly connecting a snubber capacitor in parallel with a transistor switch(Tr), turning ON and OFF said Tr only once per 1 AC cycle and setting a sufficiently large time for turning OFF a pair of Trs of arms opposed to each other upward and downward so that said pair of Trs may return to the original condition. CONSTITUTION:Each of snubber capacitors 51-56 is directly connected in parallel with each of Trs 31-36. When Trs 31 and 32 are turned OFF and ON respectively, an electric current iu flows from a motor terminal U via the Tr 32 to the negative electrode of a power source 1. When the Tr 32 is turned OFF at this point of time, the current iu is received by a capacitor 52 and the half of said current, by a capacitor 51 a little later. As a result, the bath voltage of the Tr 32 rises with a gentle inclination determined by the electrostatic capacity of said capacitors 51, 52 and the current iu, and reaches a source voltage VDC after a charge and discharge time. When a set time for both of said pair of series transistors to be turned OFF is so set as to be longer than said charge and discharge time, it is possible to obtain a good transistor inverter. |
