rpm control on single-phase-motor-with-capacitor

Thread Starter

Mullins

Joined Dec 31, 2021
168
Hi to all. Long time I not be here.
Please can you help me to find a valid solutions for Lathe motor?
The motor is 400w single phase and now it's running with a capacitor. He don't have start capacitor. He have only run capacitor.
My goal is to control the rpm without losing power.
I saw some time ago one controller which need to put one rpm sensor to the motor but I cant find it again.
 

LesJones

Joined Jan 8, 2017
4,172
Controlling the speed of a single phase motor by changing the frequency does not work very well.
Getting a three phase motor and a VFD is a much better solution. Even that will NOT give constant power over the speed range. It can give close to constant torque but that is NOT the same as constant power. If you set it to half it's design speed it would need to provide twice as much torque for the power to remain the same.

Les.
 

MisterBill2

Joined Jan 23, 2018
17,814
OK, the first question is how accurate do you want the speed control?? If it is like fan controls where there is high, medium and low, it is not that complex or difficult. Setting and holding an exact speed usually requires some sort of speed feedback. Holding a constant torque (not losing power) takes a lot more effort.
Using the same motor, it will require a controller that senses the speed somehow if the need is to hold a given speed while machining things.
A non-electrical scheme would be a mechanically adjustable dual pulley arrangement variable ratio system. I have seen one on an injector pump testing stand that covered a wide spread of ratios. I think it was a "Hartridge" brand machine.
 

MaxHeadRoom

Joined Jul 18, 2013
28,513
As Les said, the 1ph motor does not control well, it is OK for the likes of fans and light duty applications, but for a lathe you either require the 3ph/VFD version, OR there is the 2hp to 3hp DC TM motors and the MC2100 PWM controller.
 

Thread Starter

Mullins

Joined Dec 31, 2021
168
Thank you for your advice.


Getting a three phase motor and a VFD is a much better solution
I have 3 phase motor and I have Mitsubishi inverte 220vac mono phase =>220vac three phase but it's not working well. he loss torque. I saw on amazon inverter 220vac mono phase =>380vac three phase but the feedback of the owner are contrastant. Since it cost about 250€ i'm not going to buy it.

@MisterBill2
I can accept even solutions like "fan controller" but must not change to much the torque. When you are making thread with lathe you need slow power but enough torque. By the way I can add a sensor if necessary to my motor.


there is the 2hp to 3hp DC TM motors and the MC2100 PWM controller.
I'm going to look in to my garage I think that I have the controller and the motor. I need to remove the flywheel because of the inertial. do you think this is going to disturb the control board strategy?

For the signal I will use zk-pp2k


Since I am mechanic I have many bldc motor from 700w to 2kw .
Do you know some controller for this kind of motor?
 
Last edited:

LesJones

Joined Jan 8, 2017
4,172
Can your 3 phase motor be configured in delta instead of star ? If so it would work on 220 volt phse to phase instead of requiring 380 volts phase to phase. This may be the problem with running it from the VFD that you have. (Also VFDs with 220 V phase to phase output are much cheaper than the 380 V version.) I thiink I paid about £50.00 on Ebay for a VFD to drive a 1 HP motor. This was in 2014 so priced have probably gone up since then.

Les.
 

MisterBill2

Joined Jan 23, 2018
17,814
For turning threads certainly slower speed and greater torque are required. That is usually done by changing the gear ratio in the drive area. At least that is how it was done in the three different lathes that I have used. On one much smaller lathe that I saw but never used, there was a section with stepped pulleys and leather belts to change the chuck rotation speed and torque. No motor speed control.
 

MaxHeadRoom

Joined Jul 18, 2013
28,513
I'm going to look in to my garage I think that I have the controller and the motor. I need to remove the flywheel because of the inertial. do you think this is going to disturb the control board strategy?
For the signal I will use zk-pp2k
Since I am mechanic I have many bldc motor from 700w to 2kw .
Do you know some controller for this kind of motor?
It is best to remove the flywheel for this application, ensure the freq gen unit you specify can go down to 20hz .
For Controllers for the BLDC, you would need to know the voltage & what kind of commutation method they use.
 

MisterBill2

Joined Jan 23, 2018
17,814
Since all brushless DC motors are driven via a controller there is not a great deal of likely-hood that such a motor would be suitable for direct drive via 3-phase mains power.
 

Thread Starter

Mullins

Joined Dec 31, 2021
168
No at at my home I dont have three phase line, only single phase available.
I found the MC2100 PWM controller but no motor up to now. maybe I will find it later. May I use universal motor instead? Washing machine motor for example?


Since all brushless DC motors are driven via a controller there is not a great deal of likely-hood that such a motor would be suitable for direct drive via 3-phase mains power.
The controllers of my bldc motors are powered by 12vdc. I think I cant run them without any controller even if I had three phase line available.

I have even one controller for 2kw chines electric scooter. The problem is this scooter is powered with 60vdc. I want to stay on 12 or 24vdc.
 

MaxHeadRoom

Joined Jul 18, 2013
28,513
I found the MC2100 PWM controller but no motor up to now. maybe I will find it later. May I use universal motor instead? Washing machine motor for example?
The controllers of my bldc motors are powered by 12vdc. I think I cant run them without any controller even if I had three phase line available.
I have even one controller for 2kw chines electric scooter. The problem is this scooter is powered with 60vdc. I want to stay on 12 or 24vdc.
You cannot use a Universal motor on the MC2100 90v DC motors only.
You cannot run a BLDC motor off of 3ph even a VFD will not run them, unless custom equipped by the manuf.
 

MisterBill2

Joined Jan 23, 2018
17,814
Notice that NONE of the photos show the connection side of the controller. So there must be something to hide. Also, no actual connection information provided. VERY TYPICAL OF AMAZON.
 
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