Can't run MOSFET in half bridge configuration

Thread Starter

Siddharth Singh 3

Joined Jun 17, 2019
24
M2 should be complementary switch of M1. If I applied 600v across drain of M1 and source of M2, then output across resistor should be a pulse varying from 0 to 600v
 

ericgibbs

Joined Jan 29, 2010
18,766
hi,
If M1 is ON, then V5 voltage will be across R7, so current will flow in R7 to 0V, assuming that M2 is OFF.

When M1 is OFF and M2 is ON, all that happens is that M2 shorts out R7.

You obviously cannot have M1 and M2 on together else they short out V5.

E

BTW: you have changed V5 from 200v to 15v
 
Last edited:

ericgibbs

Joined Jan 29, 2010
18,766
hi,
Consider what is happening between the Gate and Source voltage on M1.

Assume M1 is conducting, so the Drain will be pulled up to close to V5 voltage.

D1 will be reversed biassed so the voltage between the Gate and Source will be almost cancelled out, so reach and low level , its no longer +15V Gate to Source, so M1 will only be partially conducting, so the R7 voltage will be very low.

Do you follow OK.?
E
 

ericgibbs

Joined Jan 29, 2010
18,766
hi,
You have short to oV on Source 1
.
E

Update:

There are number of errors on the circuit, please reduce the number of labels.;)

011 Aug. 24 12.49.gif
 

ericgibbs

Joined Jan 29, 2010
18,766
Hi,
Why are you trying to use a Half Bridge to get a controlled voltage across a resistor, what is the actual load.?
Have you considered PWM.?
E
 

Thread Starter

Siddharth Singh 3

Joined Jun 17, 2019
24
I am trying to drive the mosfet using the gate driver in half bridge configuration. I successfully drove mosfet in boost converter circuit. But I am facing problem in driving mosfet in this configuration.
 

Thread Starter

Siddharth Singh 3

Joined Jun 17, 2019
24
Thanks for the circuit. I simulated the circuit. However, there are some problems in the circuit.
The PWM1 in the schematic ranges from 0 to 130V (it should be from 0 to 5V). Voltage across R7 should range from 0-200V(for the circuit above). The gate voltage of M1 goes very high (upto 160V) whereas the gate voltage of M2 ranges from -5 to 15V.
 

ericgibbs

Joined Jan 29, 2010
18,766
hi SS,
The M2 MOSFET serves no purpose in the circuit, all it does is short the top of R7 to 0V, this means also if M1 is conducting the V5 supply is shorted out.

Could you explain how you expect to get a variable voltage across R7 and how M2 MOSFET will contribute in varying the voltage across R7, in this circuit.?

E

BTW: As this Thread is in the Homework Forum, is it a College assignment.?
 
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