Patent ID: 9621060
Date: 2017-04-11
CPC Classifications: H02M

Claim:
1. A self-excited power conversion circuit for secondary side control output power, comprising an input module, a self-excited conversion module and an output module, and the output module being electrically coupled to the conversion module and at least one load, and the conversion module being electrically coupled to an external power supply through the input module for converting a power into an input voltage, and the output module outputting the input voltage to the load, characterized in that the output module comprises a comparator unit, a driver unit and a modulator unit, and the modulator unit includes a transistor with a terminal electrically coupled to the conversion module for receiving the input voltage and the other terminal electrically coupled to the load for outputting the input voltage, and the driver unit is electrically coupled to the comparator unit and the modulator unit, and the comparator unit includes a detector electrically coupled to the load for detecting and forming a detected value; the comparator unit compares at least one reference value with the detected value and then outputs a drive signal to the driver unit, so that the driver unit triggers the modulator unit to adjust a duty cycle of the input voltage outputted by the transistor, so as to achieve the effect of controlling the self-excited power conversion circuit to output a constant power directly from a secondary side, the comparator unit further includes a first error amplifier, and the driver unit includes a first comparator and a triangular wave oscillator, and the detector is a voltage dividing resistor for detecting the input voltage received by the load to form the detected value; the first error amplifier has a negative input terminal coupled to the voltage dividing resistor for receiving the detected value, a positive input terminal for receiving the reference value, and an output terminal coupled to a negative input terminal of the first comparator, and the first comparator has a positive input terminal coupled to the triangular wave oscillator and an output terminal electrically coupled to a gate of the transistor.