Abstract: The present invention relates to a controlling method for multi-leg isolation DC/DC converter with wide input voltage scope, in which a transformer having at least three primary winding coils and one secondary winding coil is provided in a multi-leg DC/DC converter. Moreover, a converter controlling module is provided to treat the DC input voltage and the DC output voltage received from the multi-leg DC/DC converter with an over voltage determination, therefore the converter controlling module is able to output a proper driving signal to a plurality of power switch sets of the multi-leg DC/DC converter for making the power switch sets be operated at different ON/OFF states, so as to make the transformer has a specific coil turn ratio. By such way, the DC input voltage of the multi-leg DC/DC converter would be automatic modulated for facilitating the multi-leg DC/DC converter to provide a stable DC output voltage.

Abstract: The present invention relates to a double-output high-efficiency LED light-modulating circuit, comprising: a single-stage flyback power factor corrector, a DC/DC convertor, an LED module, and a light-modulating switch. In the present invention, it mainly utilizes the single-stage flyback power factor corrector for carrying out the purposes of reducing the components of an LED luminaire controlling circuit and increasing the circuit power conversion efficiency. Moreover, the double-output high-efficiency LED light-modulating circuit further includes a twin-bus light modulation framework, which can not only reduce the cross voltage of the power switch in back-end DC/DC convertor, but also process a high-frequency light modulation and a low-frequency light modulation to the LED luminaire. Therefore, because the cross voltage of the power switch has been reduced, a power switch with lower Rds can be used in the back-end DC/DC convertor for increasing switching speed and reducing switching losses.