So, I ordered timing belts and pulleys from China. Now I am waiting for them. Without this parts, the following works with hardware are not possible. On the other hand, there is time to think about electronic or programming part. The question remains about the power electronics for controlling the motors.
I use the 3 bipolar stepping motors in this project. They have 1,8 degree step, it is 200 steps per full rotation. But by electronics is possible to increase this resolution to 400 steps per rotation. I did not make calculations about how many steps is needed to move the axis by 1 mm, because the scaling and calibration will be possible at the solfware level.
Now for testing, I'm use the integrated half-h driver L293D. To testing it enough, but it has only 0,6A output current by chanel, so I can't run the motor for full speed and torque. To avoid overheating, I had to reduce the voltage to 12 volts (from 24V as nominal).
I made a prototype of H-bridge from MOSFET transistors, but it took 8 pieces for each motor (24 transistor for 3 motors). This is a possible solution, as such driver holds up to 50A per chanel, which is almost 20-fold more that needed. But the price for mosfets is too high, and the complexity of build the driver for each motor makes me wonder.
The possible solution it is integrated dual H-bridge L298, that can provide up to 3A of output current by chanel, and the price and simplicity of use is very tempting. The price on our stores is about 3€ for pc. + each driver is needed the external diodes and heatsink. I'd like to shake hands with the Chinese, which offers a ready-made module with L298+diodes+heatsink+capacitors of 2.5€ per item! That's I think order a couple of this modules and use them in the project.
Also, I decided to upgrade the connection of the power electronics part and the controller. Now, as planned - I connect the control signals directly to the controller. This is 4 outputs pins of the controller, and controller does all calculating how to enable the coils in the motor. Now, after studying all this datasheets, I found a IC L297. It takes control of the switching order for the motor coils, load control and overload protection, and has only two control signals: step and direction. There is a built-in ability to switch to micro step (increase the step resolution). All of this will greatly simplify the program for the controller, and will release almost half of the digital outputs. This IC is ideally paired with L298.
I use the 3 bipolar stepping motors in this project. They have 1,8 degree step, it is 200 steps per full rotation. But by electronics is possible to increase this resolution to 400 steps per rotation. I did not make calculations about how many steps is needed to move the axis by 1 mm, because the scaling and calibration will be possible at the solfware level.
Now for testing, I'm use the integrated half-h driver L293D. To testing it enough, but it has only 0,6A output current by chanel, so I can't run the motor for full speed and torque. To avoid overheating, I had to reduce the voltage to 12 volts (from 24V as nominal).
I made a prototype of H-bridge from MOSFET transistors, but it took 8 pieces for each motor (24 transistor for 3 motors). This is a possible solution, as such driver holds up to 50A per chanel, which is almost 20-fold more that needed. But the price for mosfets is too high, and the complexity of build the driver for each motor makes me wonder.
The possible solution it is integrated dual H-bridge L298, that can provide up to 3A of output current by chanel, and the price and simplicity of use is very tempting. The price on our stores is about 3€ for pc. + each driver is needed the external diodes and heatsink. I'd like to shake hands with the Chinese, which offers a ready-made module with L298+diodes+heatsink+capacitors of 2.5€ per item! That's I think order a couple of this modules and use them in the project.
Also, I decided to upgrade the connection of the power electronics part and the controller. Now, as planned - I connect the control signals directly to the controller. This is 4 outputs pins of the controller, and controller does all calculating how to enable the coils in the motor. Now, after studying all this datasheets, I found a IC L297. It takes control of the switching order for the motor coils, load control and overload protection, and has only two control signals: step and direction. There is a built-in ability to switch to micro step (increase the step resolution). All of this will greatly simplify the program for the controller, and will release almost half of the digital outputs. This IC is ideally paired with L298.
Therefore, most likely will be created board with the controller and 3pc of L297, which will be connected with L298 modules.
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