Undervoltage start-up circuit and start-up method of flyback converter based on high-voltage input

Abstract

The present invention provides an undervoltage start-up circuit and start-up method of a flyback converter based on high-voltage input. The high-voltage battery converts high-voltage electricity into low-voltage electricity through the input start-up circuit to provide input voltage for the control chip, and the input start-up circuit supplies the first The second capacitor is charged, and the first electrode of the second capacitor is connected to the input terminal of the control chip; the input undervoltage circuit controls the enabling circuit to disconnect before the power supply voltage of the high-voltage battery reaches the threshold voltage; when the enabling circuit is disconnected, the control chip It is forbidden to use. When the power supply voltage reaches the threshold voltage, the control chip operates normally, and the control chip provides a control signal for the switch MOS tube of the flyback converter; when the output of the flyback converter is normally established, the power supply of the control chip is started by the input The circuit is switched to provide the output voltage; the self-shutoff circuit cuts off the input start-up circuit, so that the input start-up circuit stops charging the first electrode of the second capacitor, and reduces the power consumption brought by the input start-up circuit during normal operation.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to an undervoltage start-up circuit and start-up method of a flyback converter based on high-voltage input. Background technique [0002] As the circuit structure of the vehicle-mounted inverter becomes more and more complex, in order to fulfill different functional requirements, there are more and more auxiliary power supplies in the inverter. The circuit usually used for the auxiliary power supply in the vehicle-mounted inverter is a flyback conversion device (flyback), the simple main circuit topology can be as figure 1 shown. With the popularization of new energy vehicles, the various working conditions of vehicles are more complicated, and high-voltage batteries are used in new energy vehicles. When the normal power supply of the vehicle inverter is abnormal, an auxiliary power supply in emergency situations is required The core device IGBT drive power supply in the...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide an undervoltage start-up circuit and start-up method of a flyback converter based on high-voltage input, so as to solve the problem that the input current of a flyback converter powered by a high-voltage battery is relatively low when the input voltage is relatively low. The problem of thermal risk

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