Hi guys,
I want to replace a variable speed gearbox which coupled two shafts, with a 1hp 3 phase induction motor. As the first shaft rotates, the second shaft can be rotate at variable speed through the speed adjustment nob on the gearbox. Now, I want to replace this gearbox with a 3 phase motor. The idea is something like that: an encoder reads the current speed of the first shaft using arduino uno (or mega) and arduino generate a pulsing signals to drive the motor coupled to the second shaft through IGBT driver and rotate the second shaft with the speed equal to the first shaft speed, in addition arduino should be also able to alter the speed of the motor using potentiometer as a portion of the first shaft speed. In other word, the speed of the second shaft should be equal or less than the speed of the first shaft, and if speed of the first shaft alters, speed of the second one also alters but with the same ratio which set with potentiometer. Regardless of the coding, is implementing such operation possible using an encoder, arduino, and IGBT drive? I am totally new with arduino but I can lean anything if requaired.
Am I correct in thinking that you propose to disconnect the input shaft from the output shaft and allow the input shaft to rotate freely with its speed being monitored by an Arduino?
And use a separate motor to cause the output shaft to rotate at a speed that is in some way related to the speed of the input shaft using the Arduino to produce the control signal needed to get the output shaft to rotate at the appropriate speed?
I know nothing about driving a 3-phase motor but, assuming you know how to do that then an Arduino could detect the speed of the input shaft and produce an output signal derived from it.
However I wonder at the implications of removing the load from the input shaft - won't that have an effect on the behaviour of the input shaft? And in the same vein I wonder if the gearbox coupling between the input and output provides damping for the behaviour of the output shaft that won't be available if the two are disconnected? However these considerations are well beyond the scope of this Forum.
Robin2:
Am I correct in thinking that you propose to disconnect the input shaft from the output shaft and allow the input shaft to rotate freely with its speed being monitored by an Arduino?
And use a separate motor to cause the output shaft to rotate at a speed that is in some way related to the speed of the input shaft using the Arduino to produce the control signal needed to get the output shaft to rotate at the appropriate speed?
I know nothing about driving a 3-phase motor but, assuming you know how to do that then an Arduino could detect the speed of the input shaft and produce an output signal derived from it.
However I wonder at the implications of removing the load from the input shaft - won't that have an effect on the behaviour of the input shaft? And in the same vein I wonder if the gearbox coupling between the input and output provides damping for the behaviour of the output shaft that won't be available if the two are disconnected? However these considerations are well beyond the scope of this Forum.
...R
Robin, thank you for reply. Your asumptions are fully correct. I want exactly remove the mecanichal couple as you said. I also do not have any idea about the effects of removed load on the operation of second shaft, but it is not very important as the load is not a massive one. So any suggetion about type of arduino, uno or mega or what as the starting point?
Why would you then need the first motor? What is the speed difference between minimum and maximum speed of the output shaft? Are you expecting electronics to do torque multiplication?
outsider:
Why would you then need the first motor? What is the speed difference between minimum and maximum speed of the output shaft? Are you expecting electronics to do torque multiplication?
The first motor is used to run the main production line and the second motor is used to run one of the feeders. The speed of the second motor should be able to vary between 0 rpm up to the first motor speed (the first motor speed may change time to time as operator need). I want to remotly control the second motor speed for future project not torque multiplications.
Maslord:
Hi guys,
I want to replace a variable speed gearbox which coupled two shafts, with a 1hp 3 phase induction motor. As the first shaft rotates, the second shaft can be rotate at variable speed through the speed adjustment nob on the gearbox. Now, I want to replace this gearbox with a 3 phase motor. The idea is something like that: an encoder reads the current speed of the first shaft using arduino uno (or mega) and arduino generate a pulsing signals to drive the motor coupled to the second shaft through IGBT driver and rotate the second shaft with the speed equal to the first shaft speed, in addition arduino should be also able to alter the speed of the motor using potentiometer as a portion of the first shaft speed. In other word, the speed of the second shaft should be equal or less than the speed of the first shaft, and if speed of the first shaft alters, speed of the second one also alters but with the same ratio which set with potentiometer. Regardless of the coding, is implementing such operation possible using an encoder, arduino, and IGBT drive? I am totally new with arduino but I can lean anything if requaired.
Regards,
So you are wanting to implement a VFD from scratch? Why not buy one and interface to it?
MarkT:
So you are wanting to implement a VFD from scratch? Why not buy one and interface to it?
I think industrial VFD has many functions which I may not need at the moment. I guess a simple PWM with keeping v/f constant is enough for me. Please correct me if I am wrong!
Several years ago I replaced our old German wave solder machine with a CNC soldering machine. The old one ran on 208/3 phase power. The solder pump and the conveyor chain were both powered by 1/4 horse 3-phase motors with a variable speed box, as you describe.
The variable speed is NOT a gear box. It is an infinitely adjustable transmission. It has a driven steel plate on the motor side and an identical plate on the output shaft. There is a third steel plate between the those plates, set at 90 degrees and uses friction to transmit the input power to the output plate and shaft.
The center plate's position is adjustable so the speed is variable. The whole assembly is in an oil bath. Eventually the transmission will wear one of the plates and make operation erratic. Ours became that way.
Your motor power is twice what I had, so you may already have wear problems. Do you inspect the oil level in the transmission box?
If there is room, perhaps a DC motor from a treadmill would work as a replacement.
Maslord:
I think industrial VFD has many functions which I may not need at the moment. I guess a simple PWM with keeping v/f constant is enough for me. Please correct me if I am wrong!
Yes, that's exactly what a VFD provides - its not trivial circuitry at those power levels and all the
safety cutouts are important, stalled induction motors can easily overheat or burst into flames even.
Several years ago I replaced our old German wave solder machine with a CNC soldering machine. The old one ran on 208/3 phase power. The solder pump and the conveyor chain were both powered by 1/4 horse 3-phase motors with a variable speed box, as you describe.
The variable speed is NOT a gear box. It is an infinitely adjustable transmission. It has a driven steel plate on the motor side and an identical plate on the output shaft. There is a third steel plate between the those plates, set at 90 degrees and uses friction to transmit the input power to the output plate and shaft.
The center plate's position is adjustable so the speed is variable. The whole assembly is in an oil bath. Eventually the transmission will wear one of the plates and make operation erratic. Ours became that way.
Your motor power is twice what I had, so you may already have wear problems. Do you inspect the oil level in the transmission box?
If there is room, perhaps a DC motor from a treadmill would work as a replacement.
Paul
Paul, my gearbox is reduction type variable speed one as the speed of the input shaft is 1500 and the output one is 0-850rpm with torque of 2.2 to 7.5 N.m as attached photo. It may better clarify my case.
