Mosfet switching help needed...!!!

[BHARGAVSHANKHALPARA]

Hello Everyone...

I decide to make automatic cradle for baby's, for that i use magnet attraction and repulsion property. for that i attech 2 powerful magnet on movable pipe of cradle and put one coil near this magnet.

Now to obtain movement we need to energy's coil such a way that moment of cradle can be obtain.

for that i directly connect two terminal of coil with 12V DC power supply and make switching with hand. Current Rating was 2.5A when turn on. This way i obtain movement in one direction. as i increase coil voltage large movement can be obtain.

after that i decide to switching it with micro-controller so i can obtain movement in both direction by changing current flow direction. for that i use H-BRIDGE concept.

i make h-bridge using Relay but it make noise as TICK TACK.
To Avoid this problem i use power mosfet 55NF06.

Circuit diagram is attached with this post...

https://obrazki.elektroda.pl/4718987500_1392299566.jpg

Problem with mosfet is, after starting circuit mosfet start heating and after minute it become fry.

please help me, what should i do to avoid this kind of problem....?

Thank you..!!

Bhargav Shankhalpara India.

 

[FvM]

Incorrect gate drive of high side MOSFETs, 5V instead of required 12V+x.

 

[BHARGAVSHANKHALPARA]

Thanks for reply...

I cant understand...

please explain briefly...!!

 

[FvM]

Consider what's the condition to turn Q1 or Q2 fully on. You want the source voltage of these transistors near 12V, so what's the required gate voltage? You can also review known working H-bridge circuits.

 

[mrinalmani]

There is a problem in the input signal circuitry.
1. Suppose Q1 and Q3 are ON.
2. The load is connected between the source of Q1 and the Drain of Q3, therefore current must flow through both these switches.
3. Q1 is a "High Side Switch" and Q3 is a "Low Side Switch"
4. The low side switch is OK
5. But there is "insufficient source to drain voltage" in the high side switch, and therefore it fails to switch on.

I suggest you find the difference between Low side and high side switches. High side switches require more complex arrangements for switching on.
You may wish to use a gate-driver IC for driving the MOSFETS. The use of a gate-driver is a simple solution when a circuit has High Side Switches.
IR2110 is a very famous MOSFET driver.