A high voltage input step-down conversion circuit

Abstract

The invention provides a high-voltage input buck conversion circuit, comprising a switch module, a reverse flow module, an energy storage module, a voltage cut-off and freewheeling module, a voltage stabilizing and filtering module and an energy release module, wherein the switch module is used for controlling on and off of an input voltage; the reverse flow module is used for providing a reverseflow channel after the switch module is turned off; the energy storage module is used for storing and transferring energy of a load; the voltage cut-off and freewheeling module is used for cutting offoutput of the switch module and providing a freewheeling channel for the energy storage module; the voltage stabilizing and filtering module is used for performing voltage stabilizing and filtering on an output voltage; and the energy release module is used for providing an energy release channel for the reverse flow module. The high-voltage input buck conversion circuit provided by the inventioncan effectively avoid the oscillation problem of the conversion circuit, improve reliability of the circuit and avoid influence of a load on a duty ratio of an input switch, so that stability of thecircuit is improved.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a high-voltage input step-down conversion circuit. Background technique [0002] With the rapid development of electronic and electrical systems in the direction of miniaturization and light weight, in order to reduce the size and weight of power supply cables, high-voltage power supply solutions are more and more widely used. The power supply voltage of the airborne equipment is as high as 270V, while the operating voltage of the load equipment is usually within 28V. At this time, it is necessary to efficiently and reliably convert the high voltage input into a lower intermediate bus voltage or low voltage output, while satisfying stability control and EMI performance. [0003] The existing step-down conversion circuit adopts diode freewheeling, but when the load is light or no-load, the inductor current will enter the discontinuous mode. Due to the resonance of the filter induc...

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Problems solved by technology

[0003] The existing step-down conversion circuit adopts diode freewheeling, but when the load is light or no-load, the inductor current will enter the discontinuous mode. Due to the resonance of the filter inductor and parasitic capacitance, the switching node will produce a sinusoidal attenuation oscillation, which is not conducive to Circuit stability control and EMI handling

There are also synchronous rectification step-down conversions. Although the inductor current has forward and reverse flow channels, when the inductor current is in continuous mode, due to the dead time between the main switch tube and the synchronous rectifier tube, the inductor current will be from the synchronous rectifier tube. The body diode of the MOSFET conducts freewheeling, and the reverse recovery performance of the MOSFET body diode is poor. When the main switch is turned on, it will cause a large turn-off loss of the synchronous rectifier, which reduces the reliability of the device.

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