Im making a half bridge 300v 14khz square wave power supply by using two ultra fast IGBTs and a IR2153 gate driver,when the power part of the circuit is inacvtive(Vcc=0 V) the gate-emitter waveform on high side IGBT is good with peak to peak voltage of VGE=11200mV , but when the power is activated and no load is at the output of the circuit(IC=0) the waveform will contain high frequency noise with 7000mV mixed with original waveform VPP=11.3V.bmp peak to peak ,the power supply of high and low side VGE is two isolated L7812CV output,what can be wrong in my circuit?pls help me View attachment VGE HIGH AFTER CONNECTING POWER VPP=18.5.bmp
Im making a half bridge 300v 14khz square wave power supply by using two ultra fast IGBTs and a IR2153 gate driver,when the power part of the circuit is inacvtive(Vcc=0 V) the gate-emitter waveform on high side IGBT is good with peak to peak voltage of VGE=11200mV , but when the power is activated and no load is at the output of the circuit(IC=0) the waveform will contain high frequency noise with 7000mV mixed with original waveform VPP=11.3V.bmp peak to peak ,the power supply of high and low side VGE is two isolated L7812CV output,what can be wrong in my circuit?pls help me
You are measuring high side.
So you need a differential measurement.
One at VS the other at HO.
Are you using two different channels for that and use the scope "difference" function?
* If so, then either your probes are overload ( 300V !) --> use HV probes.
* Or your scope input stage is overload: --> select a higher input voltage range on both channels.
Klaus I measured with one probe only at HO and VS .The VGE voltage peak to peak is 11V .300V is for the power side (Vcc) .I measured VGE of low side with that probe and os and it had no noises
What kind of probe? You need a high voltage differential probe for a reliable measurement, under circumstances a difference measurement with two equal probes as mentioned by KlausST can work.