Sensor less vector vs closed loop vector

[A_Camera]

A_Camera, thanks for the link. That looks like a better option especially with the detachable panel.

I agree about the panel, but if the ability to detach the panel is important then if you decide to go with the Bosch you should also buy the cable so you could easily detach it. I bought a 3m long cable with it and yes, it is nice to be able to detach it but I am missing a simple feature or two from the panel. One is that there is no cable fix at the back of the panel or in the VFD where you remove the panel from, so this is something to be solved by the user. The other is that if you remove the panel it becomes a tiny plastic box without any screw holes or screw ears, so it can't easily be moved to a control box somewhere away from the VFD without a modification or special fix. None of those two points are a deal breaker, but it is a bit annoying to have to come up with your own solution. I will eventually make a cover panel which allows seeing the LEDs indicating the status even when the panel is detached and which also will hold the cable at the VFD end. I will move the panel to my controller box for better accessibility since my VFD is not going to be where it is easily seen.

Anyway, if you decide to go for the Bosch you should also consider buying some other items, so have a look around before placing the order. My order looked like this, and I think this is the minimum you will need.



If you decide to order a Bosch 2.2kW and consider buying a brake resistor and the cable clamp you must check that those fits even the 2.2kW version. I am pretty sure that the panel cable is the same.

They have even other interesting items which I would have bought if I not already had those, so have a look around. Anyway, it is a good company to deal with, my experience is positive even with the after sale support. I had a few questions and received all the help I needed.

I will be using an inverter duty 4 pole motor to get the best performance over the speed range needed. they do one that can go from 150-3000rpm so should be perfect.

I don't have any other experience than with the 24kRPM motor I have, but guess you are right. Anyway, for the task you have, that motor is definitely better than using a high speed motor at low RPM, even if you would have a real closed loop vector drive.

As you say the advantage of the encoder feedback is that it goes down to 0 rpm so good for indexing.

Im still confused about the PID feedback as the inverter I mentioned shows an external connection to a speed pulse.

For the extra money of the closed loop VFDs I think I'll try the senorless first and upgrade later if and when needed.

Many thanks All

The way I understand is that PID means that the VFD have speed feedback, so it can keep up the speed according to the PID setup parameters, but in a real closed loop system you even have information of the shaft angle, so you know EXACTLY by the degree accuracy of the used sensor where the shaft is, even if it would be at zero speed, stopped. That way you can apply exactly the right voltage/current/frequency combination to pick up the speed or to start the motor the way you need it. An elevator may not be a good idea to start with maximum speed from zero the fastest possible time, while a CNC spindle is just fine by that. So it is not just about the speed but also about the position of the shaft angle. It simply provides a more accurate regulation than simple PID.

That is my understanding of the differences, but there must be more than that, since the price difference indicates that. Anyway, no, I don't think you need it, unless you really need EXTREMELY low RPM, like below 10 RPM or so.