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Hi alalde, Thank you very much for your reply. I think a single phase sensor is ok for me because I don't require phase angle and high accurat measurement. Thanks.

I am using a AC brushless servo motor (3 phase 220VAC) and want to monitor the current load using a current sensor. My question is: Do I have to use a 3 phase current sensor or a single phase one is ok? Thanks.

For a servo amplifier, there are current mode, velocity mode and position mode. What is the difference between them. In some control system design, current mode is used even when velocity of the motor need to be controlled. I am really confused at this point. Any artical or book could be...

The gearbox is a speed reducer. The PID loop time of the controller is 62.5us. If the lowest speed is 0.1rpm, what encoder resulotion should be used for this application. I am trying to find a way from controller side if it is possible because the gearbox is there already and we have some...

Hi skogsgurra, Thanks for your points. First, the stepper motor is not suitable for my application. The pump has speed control and pressure control function. Actually, we used a 1:200 gear box between motor and pump. But sometime we still need to run the motor at about 0.1rpm. Highest speed is...

Thanks for all of your opinions. I am using a AC brushless servo motor to control pump's injection speed. Sometime we need it run at very low speed. The motor we are using has resolver with 1 speed and 500ppr. The driver converts it to quadrature incremental encoder signal, so the controller...

I have an application but I am wondering how I can implement it.

I am using AC brushless servo motor in my motion control system. From the motor's spec, the speed can goes from 0 to 4000RPM. I am wondering how low speed of the motor I can get in my system. If I want 0.01RPM for the motor, what pre-requisite is needed, resolution of encoder, mechanical...

Hi EdDanzer, Actually, this is same machine related to the gear box problem, but not same issue. Because the machine need to hold the pressure in pump and knows the position when the system loss power. So it is impossible to home the axis on start up. Now I have a solution to do it. But it is...

Does anybody know which manufacture has product which is AC brushless servo motor with absolute encoder. And usuaully how much more expensive is it compared with an AC motor with resolver or incremental encoder? Thanks.

Hi EdDaner, One thing has been found which is mechanical wear in the harmonic drive. Some parts were worn and there are some trash in it. I hope it would be ok after this problem is fixed. Thank you very much for your kindly help. Thanks everyone.

There are a speed reducer(harmonic drive), a roller screw then the piston.

To EdDanzer, I run the system without load, it worked fine. So Is it still tuning problem? Thanks.

To jbartos, it is closed-loop control. there are velocity feedback, velocity feedforward and intergration in the controller. And current loop and speed loop in the amplifier. I am wondering how come the current increasing seems time related.

I run the motor for 13 minites this time. The operating temperature is 25.1c at the start and 29.5c degree at the stop. the current increased from 3.8A to 11A.