Hi all,
I'm trying to power a bipolar stepper motor with a voltage of 24-48 V and current of 4.2 A. I'm not allowed to use a predesigned motor driver, just IC's and transistors. After doing some research it seemed like the best choice was to just build a dual h-bridge, I built one with high power, high current darlington pair transistors, but the stepper motor is only buzzing not moving. So I assume it's not providing enough current to the motor.
Does anyone have any experience with schematics for h-bridges or any IC's that would be able to run these kind of currents?
That is not the average hobby stepper motor. We like the know the specs, can you give a link to it ?
Is that a stepper motor with only 4 wires ?
Upload your schematic so we can check it.
You know that darlington transistors are so 1970's ? Modern mosfets can handle those currents without problem.
If the stepper motor is slow, you could omit an IC, and control the H-bridge completely with the Arduino. With dual H-bridge you need 8 output pins of the Arduino to control every part of it. It's just an idea, and might be useful during testing. Perhaps it is not practical.
markb847:
Hi all,
I'm trying to power a bipolar stepper motor with a voltage of 24-48 V and current of 4.2 A. I'm not allowed to use a predesigned motor driver, just IC's and transistors. After doing some research it seemed like the best choice was to just build a dual h-bridge, I built one with high power, high current darlington pair transistors, but the stepper motor is only buzzing not moving. So I assume it's not providing enough current to the motor.
Does anyone have any experience with schematics for h-bridges or any IC's that would be able to run these kind of currents?
Thanks
You need to do some more research and learn about chopper drives. These are current
controlling drives using the motor winding inductance as the inductor in a step-down
converter.
Note that your 4.2A stepper motor doesn't have a voltage rating (other than for
insulation breakdown), it has a winding resistance - which will likely be about 0.5 ohms.
Without step-down conversion there is no way at all to run it efficiently at both low and
high speeds.
Well, which of the 4 stepper motors do you have ?
Perhaps you can make a photo of the label, so we can see the type number ourself.
It turned out to be as MarkT wrote. The winding is 0.5 ohm and those need a current chopper driver.
The H-bridge will work, but I don't know what will happen when you use the H-bridge with that stepper motor.
If you use 24 Volt, perhaps the resistors or transistors should be adapted. And I like to see 4 protection diodes on the output pins.
Note that if both the inputs are high, the whole H-bridge will go up in smoke.
If you just want to make that particular motor spin, you can do it with your 24 V power suppy and a 1 amp H-bridge, provided that you put 24 ohm, 50 watt resistors in series with each motor winding. Yes, that is right, 50 watts. The resistors will get extremely hot and probably need a heat sink. See Jones on Stepping Motors for L/R motor drivers (and everything else you didn't want to know about steppers).
MarkT- thanks. i looked up the current control. Can you give any suggestions to going about doing this? this is my first time working with motors.
Industrial stepper motor driver is the item you're lacking. Gecko drive might be one of the
cheapest if I recall. The 4A puts you well outside the range of any single-chip driver.
