H-Bridge DC motor driver

[Hero999]

Just wondering, how can the resistance increase after it starts..? Isn't that the resistance of the coil..? I dunno much about construction of the motor..

Perhaps I haven't worded that very well. When you spin a motor it generates a voltage. The same is ture when it's connected to a power supply except the voltage counteracts the current from the power supply. For exampe if your motor generates 50V when spun at the maximum speed, it will draw (60-50) / 5 = 2A when powered from 60V.

When you say the input capacitance, u mean the capacitance of gate-source and gate-drain..?

As for purchasing the special driver IC, we're kinda on a tight budget...

Thanks.... Hmm, if I use 1Mega Ohm resistor, that would certainly speed up the charging and discharging time of the capacitance rite (theoritically)..?

You've got that backwards, you need to reduce the resistor value, remember the RC time constant. To get the real answer to this question, look at the datasheet then figure out how long it will take for the gate capacitance to charge to the voltage that will alow the desired current to flow to work out the switching speed.

 

[MrNobody]

Perhaps I haven't worded that very well. When you spin a motor it generates a voltage. The same is ture when it's connected to a power supply except the voltage counteracts the current from the power supply. For exampe if your motor generates 50V when spun at the maximum speed, it will draw (60-50) / 5 = 2A when powered from 60V.


You've got that backwards, you need to reduce the resistor value, remember the RC time constant. To get the real answer to this question, look at the datasheet then figure out how long it will take for the gate capacitance to charge to the voltage that will alow the desired current to flow to work out the switching speed.

Ok... thanks very much.. will look into it..

 

[wailyounis]

Hey..
I need help in designing H bridge motor driver circuit to drive a DC permanent motor using N-MOSFET.

The motor specs are:
Type: dc permanent magnet motor.
Voltage rating: 24 Volts dc
Power: 250W

I need help.. Can somebody please help me.. Thanks..

 

[Hero999]

I will help you but you need to read this entire thread and make an attempt at designing it for yourself before I help you.

 

[ericchee]

Since optocoupler is not recommended due to its speed, what is recommended to isolate motor from control circuit? 2N2222A with RC filter?