hello,
i have big problem with my friend wheelchair
damaged control unit
i need to design new one with simple draw
the motor is MBT1141M 24 volt 0,55kw
i try make simple an555 ic pulse width with 10v and i sucsess with it
but i don,t know the mosfet to put i try irfz44n heat and damage
irf3205 same irfp460 same
really i pay too much for trying mosfets what i do? please help

 

Looking at a couple of the Mosfets chosen, it looks like you are on the right track.
For some help please post a schematic of the circuit you are using.
I'm assuming you need forward/reverse and speed control.
Edit: And there are two motors -- correct ??
Do you have a schematic of the original damaged circuit also ??

 

i try make simple an555 ic pulse width with 10v

If by 10V you mean the supply voltage to the 555, then the output driving your MOSFET will be less and is not enough to turn it fully on and reduce to Rds, causing too much heat. I'd like to see maybe 12V at the gate of the MOSFET, to eliminate this issue.

Even fully on, the MOSFET will be dissipating more than 10W, and requires a BIG heat sink.

 

yes you are right i need forward/reverse and speed control schematic real one working
to do it
i don,t have schematics i do it by manual
can you help
if you have one with forward and speed control OK no problem he need to move only because of his legs can,t walk
thanks for your time
best regards

 

Have some more questions.

1. What do you have for a controlling device - Is it a joystick with pots? - for example. Be specific

2. Is the battery voltage 24vdc or something different ?

3. How are you getting the 10 volts for the 555 ?

4. How are you controlling the 555 to get the PWM ?

5. How did you connect the Mosfets which (unfortunately) burned up. ?

You really need to post a wiring diagram of what you have done or tried so far.
There are various ways to accomplish this project, but more details are required to give you accurate advice.

As wayneh pointed out you need 10-12VDC driving the lower Mosfet gate in a bridge circuit and if using all N-Channel Mosfets you need 10-12v MORE V+ than the voltaje on the top Mosfet Drain.
Note: There are many circuits posted on the internet of this type which are just plain WRONG !

 

1. What do you have for a controlling device - Is it a handle with switch on-off

2. Is the battery voltage 24vdc -2battery 12v 55ah

3. How are you getting the 10 volts for the 555 - 78L10

4. How are you controlling the 555 to get the PWM ? PIN 3 OUT (+) TO MOSFET GATE WITH RESSISTOR 220 OHM

5. How did you connect the Mosfets which (unfortunately) burned up. ? PARALLELED

 

You really need to post a wiring diagram of what you have done or tried so far.

How is the switch handle connected to the 555 circuit. ?
How are the Mosfets wired to the motor ? Where is V+ in relation to motor
to Mosfets to gnd?
Are the batteries wired in parallel or in series?
NEED diagrams of what you have tried. Cannot help without those

This is the type of Mosfet circuit you need to control a motor with speed control and forward-reverse.

Example only - you need the higher current N - Mosfets, plus P Mosfets, plus variable PWM fed to A or B for forward or reverse.

You need more than a handle with a switch to vary speed.
Does the handle have potentiometers in it ?

 

How did the original control system work on the wheelchair ?

Edit: Explain it like you are teaching someone to operate it for the first time.
How to go forward, backward, turn stop etc.

It may seem like too many questions but all of these details are extremely important to figure out how to use some of what you already have.

 

The schematic in post #7 had the PMOS upside down
Here's the correct image