Patent ID: 9654020
Date: 2017-05-16
CPC Classifications: H02M

Claim:
1. A smart matching step-down circuit, comprising: an alternating current (AC) input terminal connects to an external power supply to input a first AC within a predetermined voltage range; a rectifier filter circuit connects to the AC input terminal for rectifying and filtering waveforms of the first AC to form a first direct current (DC); an input end of a switching circuit connects to the rectifier filter circuit, and in response to control signals, the switching circuit is turned on or off to output a pulse voltage; a high voltage BUCK control step-down circuit comprises a voltage step-down inductor, and a voltage step-down filter capacitor, wherein a first end of the voltage step-down inductor connects to an output end of the switching circuit, and a second end of the voltage step-down inductor connects to a positive pole of the voltage step-down filter capacitor for performing a voltage step-down process and a filtering process toward the pulse voltage so as to output a second DC; a floating zero potential control circuit comprises fly-back diodes, a cathode of the fly-back diodes and the first end of the voltage step-down inductor cooperatively connect to a floating ground; a voltage detection and feedback circuit comprises an input end connecting to the second end of the voltage step-down inductor to detect the second DC so as to generate a feedback message; a PWM controller comprises a feedback end connecting to an output end of the voltage detection and feedback circuit, and a control end connecting to a controlled end of the switching circuit, in response to the feedback message, the PWM controller is configured to output control signals controlling a pulse width of the pulse voltage; a full-bridge DC/AC converter circuit comprises an input end connecting to a positive pole of the voltage step-down filter capacitor to convert the second DC to the second AC; an AC output end connects to the output end of the full-bridge DC/AC converter circuit to output the second AC; an output voltage detection circuit connects to the AC output end to sample voltages of the second AC from the AC output end so as to generate a first sampling voltage; and a conversion controller connecting to the output voltage detection circuit and the full-bridge DC/AC converter circuit, the conversion controller is configured to controlling a duty cycle ratio of outputted waveform of the full-bridge DC/AC converter circuit in accordance with the first sampling voltage so as to stabilize the second AC.