| 摘要 |
PURPOSE:To reduce the tertiary higher harmonic component of the input current and improve the power factor, by a method wherein in a voltage doubler rectifier circuit, a power source is short-circuited through smoothing reactors during a period when the charging current of a capacitor does not flow. CONSTITUTION:The power source short-circuiting circuit comprises smoothing reactors 3, diodes 1, transistors Tr7' and 7 and a current detector 8. Because a forward voltage is applied to the Tr7' during a period of electric angle 0-pi, the Tr7' is on from an electric angle 0. When the input current reaches the highest limit value of a reference voltage, the output of a comparing circuit 9 becomes negative, so that the Tr7' turns off. On the other hand, when the input current decreases to the lowest limit value of the reference voltage, the Tr7' turns on again. Because the Tr7' repeats such an on/off operation and the charging current of a capacitor C2' suddenly increases when the electric angle is in the vicinity of pi/2, the off period of the Tr7' elongates. When the electric angle is over the point of pi/2, the charging current of the C2' attenuates, and the Tr7' repeates the on/off operation again. Similarly, the Tr7 operates during a period of electric angle pi-2pi. |
