Wide-duty-ratio MOSFET isolation drive circuit

Abstract

To solve the problems of the prior art, the invention provides a wide-duty-ratio MOSFET isolation drive circuit. A rising edge and a falling edge of a PWM signal are captured and then an edge pulse signal is formed, the edge pulse signal is input to a primary side of a transformer, an output pulse is shaped at a secondary side of the transformer and finally recovered to be a PWM drive waveform with positive and negative voltage output, and then an MOSFET can be driven. Signals and energy are instantly transmitted at the edge of PWM, so the MOSFET isolation drive circuit is wide in isolation output wide duty ratio, which can reach 0-99.5%. A primary side pulse generation mode is different from a conventional capacitor-transformer combination driving mode, so a self-excitation frequency problem does not exist. If an input duty ratio abruptly changes, the output can follow with the change. No low-level gain phenomenon will occur, and a switch tube will not be connected for short time and burn out.

Description

technical field [0001] The invention relates to a MOSFET isolation drive circuit, in particular to a MOSFET isolation drive circuit with a wide duty cycle. Background technique [0002] MOSFET isolation drive circuits are widely used in power supply systems. The performance of isolation drives directly affects the quality of power output. For MOSFET isolation drive circuits, at present, optocoupler isolation and magnetic coupler isolation are mainly used. Due to optocoupler It can only realize signal transmission, and it is necessary to add an auxiliary source circuit on the isolation secondary side. The isolation drive circuit is relatively complicated, and the traditional magnetic coupling isolation drive has a problem of low level rise when the duty cycle changes suddenly, which leads to MOSFET errors. Triggering, seriously affects the performance index of the power supply, and even causes the power MOSFET to burn out. With the development of power supply technology, the ...

AI Technical Summary

Problems solved by technology

[0002] MOSFET isolation drive circuits are widely used in power supply systems. The performance of isolation drives directly affects the quality of power output. For MOSFET isolation drive circuits, at present, optocoupler isolation and magnetic coupler isolation are mainly used. Due to optocoupler It can only realize signal transmission, and it is necessary to add an auxiliary source circuit on the isolation secondary side. The isolation drive circuit is relatively complicated, and the traditional magnetic coupling isolation drive has a problem of low level rise when the duty cycle changes suddenly, which leads to MOSFET errors. Triggering, seriously affects the performance index of the power supply, and even causes the power MOSFET to burn out. With the development of power supply technology, the input range and load capacity of the switching power supply are improved. When the load is switched or the input voltage jumps, the duty cycle will appear transient , the traditional magnetic coupling isolation drive will not work properly, therefore, it is necessary to develop a reliable isolation drive circuit

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