Drive circuit for preventing oscillation of grid drive signals

Abstract

The invention relates to a drive circuit for preventing the oscillation of grid drive signals. The drive circuit is characterized by comprising a buffer circuit, an amplitude limiting circuit and a rapid discharge circuit, wherein the buffer circuit receives and processes a drive signal PWM (Pulse Width Modulation) and then outputs the signal to the amplitude limiting circuit; the amplitude limiting circuit processes the received signal and then respectively outputs the signal to the grid of an MOS (Metal Oxide Semiconductor) transistor and the rapid discharge circuit; and the rapid discharge circuit also receives the drive signal PWM. The drive circuit has the advantages of lowering the voltage change rate of the MOS transistor, decreasing the open surge in the opening process, reducing the impact and damage to the MOS transistor, improving the EMC (Electro Magnetic Compatibility) property of the whole switch power supply, decreasing the turnoff loss, effectively avoiding the abnormal oscillation of drive signals, protecting normal working states of the MOS transistor and the circuit, and the like.

Description

technical field [0001] The invention relates to a drive circuit for preventing grid drive signal oscillation, belonging to the technical field of switching power supply drive, in particular to a drive circuit for preventing grid drive signal oscillation. Background technique [0002] At present, most switching power supply circuits use power devices, and power MOS tubes have been widely used in small and medium power power supply products due to their advantages of fast switching speed, low driving power and low power consumption. Two situations often occur in a circuit using a bridge topology. First, during the conversion process of two power devices on the same bridge arm, the gate drive signal will oscillate, and the loss of the power device is large at this time. When the oscillation amplitude is high, the power MOS tube that should be turned off will be turned on, thus causing the two power MOS tubes on the same bridge arm to be directly connected to form a short circui...

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Problems solved by technology

However, the improvement effect of the above methods is not very obvious, and it is more affected by product structure and human factors.

Second, because the drive current provided by the control signal to the MOS tube rises rapidly (rising edge), it will cause a high turn-on surge, resulting in impact damage to the MOS tube, which will affect the EMC characteristics of the entire switching power supply to a certain extent

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