I got a question In H-bridge connect a resistor from gate to source,pls have a look

[longcrystal]

I have between two circuit one is resistor no connected gate to source and resistor connected gate source.a


May i know what is the main purpose between this two circuit . i like to know , because i have design my sine wave inverted , i doubt in this consideration . hope someone can clearly explain the purpose , thank for everyone to helping;-);-)

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i thin already read through many posted , sorry for posting this thread , i think it was the main reason ,, put one resistor to gate to source it would be prevent the floating gate protection and the main reason is without this resistor u easy burn u IR2101 and third reason for my personal , i had design a sine wave inverter , i use one button for on/off this circuit , but i have find out a weird problem is very hard to turn off , in my simulation design is no facing this problem , but in real life when i try to turn off need to press two three times only can turn off and something depend on luck . so i think this is the reason for put a resistor , if anyone got any extra opnion and suggestion about calculation or explanation can put ,,, i appreciate to willing learn from anyone .


regard

 

[BradtheRad]

1.

An N-mosfet has its gate referenced to the source terminal. In order to turn on, the gate voltage needs to be higher than the source terminal. The source terminal should have a definite path to ground, for proper operation.

However your upper two mosfets appear not to have this at times when the lower two mosfets have shut off.

Do you have a load connected? Try a resistive load at first, and it should provide a path for the gates to have a definite reference, both to turn on and to turn off.

2.

Although your schematics show no zero ground, this is probably corrected in your real circuit, because you say you got it working to some degree.