h bridge

[066]

how can i get more output from my h bridge?

 

[dknguyen]

Define output please. An H-bridge outputs many things. But for the most part, you need to get another H-bridge or heavily modify your current one.

 

[066]

i am using this desing and the out put for the moter is to low around.2v

https://www.robotroom.com/BipolarHBridge.html

 

[Salgat]

If you mean handle more current..you can buy transistors or actual components containing an H-Bridge that handle more current, though they use larger casings.

 

[066]

my moter voltage is to low how can i make that higher i used the

robotroom plan search for robot room .com

 

[dknguyen]

THough larger transistors will reduce the conduction (ie. steady state losses) they will also increase the switching losses (which vary with frequency and as a result are essentially the same at all duty cycles and cannot be reduced by reducing the duty cycle.

It's risky to try and increase the voltage an H-bridge can handle by doing something liek replacing the power transistors with higher voltage transistors because other more sensitive components (especially the ones driving the gates of the high-side transistor of the H-bridge) may directly experience the battery voltage and if they were not rated to do so by the designer (which is entirely likely since the circuit was not designed to tolerate higher voltages) these components may fry. It's not just the power transistors that have to tolerate the higher battery voltage.

But if you know how the circuit is exactly then you can just modify anything that is needed. If this is the H-bridge you are referring to:
https://www.robotroom.com/BipolarHBridge.html

Then you can replace the power transistors with higher voltage BJTs and resize the gate resistors accordingly. You could also build a H-bridge thay uses FETs instead of BJTs which would tend to have lower losses where the base/gate drive circuitry would be slightly different (either simpler or more complicated depending on how far you want to go). I assume you are just starting out and the H-bridge is only used to change directions (and not speed), in which case the gate/base drive circuitry would be simpler (fanicier gate drive circuitry is needed to turn the transistors on and off faster in order to do things like reduce switching losses so you can switch the transistors on and off very rapidly at different duty cycles for variable speed).

https://www.modularcircuits.com/h-bridge_secrets1.htm

 

[yuchween]

how can i get more output from my h bridge?

You should try to use a darlington pair instead of a normal BJT.

I did my final year project as well and I had trouble with driving more current to the motor. So i tried to use a darlington pair and it works well.

http://www.mcmanis.com/chuck/Robotics/tutorial/h-bridge/bjt-circuit.html

 

[hatem_sniper]

thanks very much