| 摘要 |
PURPOSE:To obtain a power supply device, in which an on-duty is set in 1:1 and the generation of noises is inhibited, by controlling the magnetic energy of a positive feedback winding by a magnetic-energy control means and controlling another positive feedback winding by magnetic coupling. CONSTITUTION:In a magnetic-energy control means 16, voltage in the direction driving each field-effect transistor Q11, Q12 is rectified by a voltage doubler rectifying circuit 17 and charged to a capacitor C17, and consumed and controlled by an output control circuit 18. Consequently, the quantity of magnetic energy is also reduced, the oscillation frequency of each field-effect transistor Q11, Q12 is lowered and an output from an inverter circuit 11 is increased at the time of the large power consumption of the output control circuit 18 and the oscillation frequency of each field-effect transistor is augmented and an output from the inverter circuit is diminished at the time of small power consumption in the bi-directional magnetic energy of a current transformer CT. Accordingly, the duty ratio of the field-effect transistors reach approximately 1:1, and resonance currents are also brought close to a sine wave and noised can be reduced. |
