Thread: Huanyang VFD - another question....

poor old motor, what did it ever do to you Joe?
How slowly are you talking about? say 5 seconds from 120 to 70?
I could have a wild guess at what the problem is, but it wouldnt be a very educated one lol
You could try resting your foot against the motor shaft to give the motor something to do while slowing down
I'm not sure there is much else you can do other than changing the speed that the VSD respones to your knob twisting. I think there is a setting for that but your VSD seems to have different error messages to mine so maybe different parameters.

Stuart

Perhaps it's acting like a generator on the overrun, and being still wired for 415v is causing the VFD to whinge about it? Something a little like disconnecting the battery on some carby cars with points while it's running - the alternator still generates enough power with the battery disconnected to keep the car going...

Overvoltage on decceleration is to be expected on drives with no braking resistor, the motor has had it phase moved from lagging to leading and is performing as an induction generator charging up the VFD's filter capacitors. The other error to expect when using a 415V motor at high frequency is an over current fault if acceleration is too rapid, the motor starts to slip excessively and the current rises.

Check the drive manual, many drives can be set to self protect on overvoltage, meaning that they sort of freewheel while the voltage falls to a safe level.

Hi Crossfeed,
Are you saying the the braking resistor is used when decceleration from one speed to another and not just during braking?

Stuart

Jeckyll and Hyde and Crossfeed,
I think I understand your explanation (back EMF?).
The fact that it's still in star configuration would indeed make it likely to generate pretty high voltage - I didn't consider that.
So first I'll separate the centre point and wire it in Delta and try again. Next step will be to do this with the motor in the lathe driveline. The belt and bearings load may reduce the freewheeling ability of the motor to generate.
Lastly, if that doesn;t 'cure' it, I'll get back to you to learn more about braking resistors and their role in decelaration.
I had a good look through the manual (Huanyang) and I see that 'self protect' seems to be the default setting, but its protection mechanism seems to be to register an error. My settings prevent an over current error on acceleration - at least without a load. That may change once installed in the lathewith a big chuck or faceplate mounted. I will look out for that.
Thanks,
Joe

The braking resistor is connected to the VFD's DC bus via a transistor or IGBT which switches on when the DC bus voltage becomes too high, this applies a load to the DC bus discharging the capacitors to a safe value before it turns off.

It is not the star connection that generates the voltage it is the phasing of the VFD going to leading which is inevitable during overunning. The energy stored in the motor inertia has to go somewhere. Do a search for induction generator for a better explanation. The braking resistor provides a place for this energy to be dissipated.Note the energy stored in a rotating mass increases by the rpm squared.

The problem with running in star (415V) with a 240V VFD at high frequency is that the magnetic flux inside the motor is weak and the motor is prone to slip. When the motor slips excessively the motor falls of the peak torque and can stall, causing overcurrent trips. I have had motors do this when running at 150 Hz + at under rated power, some drives stall gracefully others trip.

Originally Posted by Crossfeed

The braking resistor is connected to the VFD's DC bus via a transistor or IGBT which switches on when the DC bus voltage becomes too high, this applies a load to the DC bus discharging the capacitors to a safe value before it turns off.

So is that "Yes the brake reisitor is used while changing speeds and not just during braking"?

Originally Posted by jhovel

Next step will be to do this with the motor in the lathe driveline. The belt and bearings load may reduce the freewheeling ability of the motor to generate.

Well it will add load but it will also add rotating mass, hence the foot idea lol
Still if thats where its going to go, thats where you need to know if it works.

Stuart

Thank you Crossfeed for the explanation.
I didn't have time to open the motor to find the star point today, but in a spare few minutes I temporarily hooked the motor up to the drive after making a suitable V-belt pulley. The surprise was the utter lack of torque of the motor in it's current (wrong) configuration! It would run but not accelerate beyond about 20Hz speed. As I turned the pot up, I could hear the windings change noise pitch - all the way up to 100Hz, but the motor didin't change speed - it looked like it was even slowing down a little.
So I allowed it to accelerate by loosening the belt tension (wasn't tight to start with). The motor accelerated as expected, slipping the belt. As soon as I increased the belt tension it slowed down again. The current drawn while all this was going on was just below 1A.
My conclusion: a star wired motor meant for 415V will draw bugger all current and develp bugger all torque as a result of no more than 240V power being applied.
Incidentally, the internal DC voltage rose to 335V at one time while the motor was not able to keep up with the frequency put to it.....
There are clearly lots of things I don't understand - yet. So I'll stick to the standatd procedure, change the motor to delta and see if it does what it's meant to - like the 2Hp motor that I intend it to replace (identical age and make but already rewired to delta and driving everything fine, just could do with more torque at low speed).
Cheers,
Joe

Hi Joe,
What do you have PD004 set at?

Stuart

Stuart, the error message is actually E.o.u.d. - the original post has a typo (damn dyslexic keyboard of mine).
Is your VFD a Huanyang?
Crossfeed, do you have any experience with Hunayangs?
Joe

Stuart - PD004 is set to 50, PD005 to 100. In fact apart from enabling the pot and setting PD005 and PD142 (motor current) which I set to 7 I have left everything at default - IIRC. I'll go and check them all tomorrow and write them down for future reference.
Joe

Hi Joe,
Yes. But I dont have any errors like yours listed. The errors on mine are Ou-1 or Ou-2 are Over-voltage at stop, Over-voltage at accel, Over-voltage at constant speed, Over-voltage at decal. So maybe pd004 isnt the correct number for "base frequency"?

Stuart

Hi Joe,
Is that what it is set to or what the manual says the default is? Mine VSDs were set nothing like what the manual says the defaults are.

Stuart

Stuart,
I'll check the lot tomorrow as I said, but I have found all the settings I looked at to match the manual. By the eay, this is a 3kW 220V single phase model which is not listed in the manual....
All my errors (the ones I've seen) display as per manual: always starting with E. and displaying characters rather than numbers.
Joe