| 摘要 |
PROBLEM TO BE SOLVED: To solve the following problems: on a switching power supply unit, some foreign countries (Europe) have international standard IEC 1000-3-2 for higher harmonic suppression, therefore there is a higher harmonic suppressed switching power supply unit using an active filter system which is one of measures against the standard, and the active filter system operates a power factor improving control circuit in order to improve the power factor along with higher harmonic suppression, however, a conventional apparatus operates the power factor improving control circuit for all loads from the minimum load to the maximum load, and power loss occurs in the power factor improving control circuit even if input power is out of higher harmonic suppression regulation, so that power supply conversion efficiency is reduced. SOLUTION: This higher harmonic controlled switching power supply unit is provided with a means of stopping the operation of a power factor improving control circuit when the input power is out of higher harmonic suppression regulation to suppress power loss in the power factor improving control circuit, thereby improving overall power supply conversion efficiency. |
