SINAMICS DCM - problem with adapting to a small motor

Dear Experts,

I have a serious problem with theSINAMICS DCM 6RA8013-6DV62-0AA0-Z converter, which basic parameters are shown below:

• armature rated DC voltage: 420 V,
• armature rated DC current: 15 A,
• rated power: 6,3 kW,
• rated field DC voltage: 325 V,
• rated field DC current: 3 A.

My task isto configure the above inverter in a that way that it be able to properly work with a DC motor, which parameters are shown below:

• armature rated DC voltage: 230 V,
• armature rated DC current: 2,6 A,
• rated power: 0,6 kW,
• rated field DC voltage: 220 V,
• rated field DC current: 0,22 A,
• rated speed: 1450 rpm.

And well… I have problem with configuration of the converter, because after starting the drive system, the motor does not work properly, saying that I mean that the motor’s work is uneven and unstable. During rotating, there are sounds like there is a problem with the bearings, I mean it sounds like the bearings are damaged. However, the bearings definitely work properly, they are in good condition. I have to add, that this motor works properly when it is powered by another power system (by the power system without SINAMICS DCM converter).

I carried out the configuration of converter in a several ways:

1. I carried out commissioning procedure using the STARTER commissioning tool. Firstly, I added the SINAMICS DCM converter to newly created project and then I proceeded to the configuration of the drive unit (the above – mentioned motor) via option Configuration drive unit.

Then in subsequent windows I entered motor’s basic parameters and the drive system.

I have to say that actually I do not use any external system in order to measure the motor speed. I rely on estimating motor’s speed based on electromotive force (EMF).

Then I loaded the project to the SINAMICS DCM converter and I saved it in ROM memory.

After starting the drive system and setting the speed, the above – mentioned signs of incorrect motor’s work appeared. The strange sounds and unstable motor’s work are noticeable – no matter what value of speed is set (I set about 1000 rpm) and the motor’s load does not matter too. I carried out tests mainly in idle state, without load.

The motor’s work is not permitted. It is completely unacceptable.

1. In the next attempt, in accordance with the instructions provided by the manufacturer of the SINAMICS DCM converter, I carried out optimization process.

The optimization procedure was performed by using STARTER and it was based on entering appropriate values in parameter p50051. I carried out the following optimizations:

1. optimization of closed – loop field – current control,
2. optimization of closed – loop armature current control,
3. optimization of speed control.

I was not able to carry out optimization of closed – loop EMF control, because the speed measurement is based on estimation EMF – and that mode makes it impossible to carry out this optimization.

However, I think that the above – mentioned control circuits are sufficient.

Comparing regulators settings before and after optimization processes, I noticed differences between them. The values of motor’s parameters was redefined and differ as well.

After starting the drive system, it turned out that after optimization processes, the motor works even worse than before optimization. So, the optimization method did not bring desired results, it did not improve motor’s work.

1. Another attempt which was carried in order to improve drive systems’ work was determination of the motor parameters’ values by carrying out a several measurements – by using a technical method and oscilloscope method.

The values of each motor’s parameter were determined and they differ from values which were set automatically by STARTER– the differences reach the order of magnitude, so they are really significant. In my opinion it is a little bit weird.

Then I entered the designated parameters to the converter and I started the drive system.

Unfortunately, the motor did not work better. It can be said that motor’s work was similar to that one which was observed after carrying optimization processes.

After that experiments, I can say that the motor works best afterQuick Commissioningprocedure (the point no. 1 from above mentioned). However, the quality of work of this drive system is unsatisfactory and unacceptable.

This converter previously was configured to work properly with motor which rated parameters were very close to rated parameters of this converter. So that is why I am sure that this converter and speed set system work properly and they are fully efficient.

To conclude, since the converter works properly with a motor which parameters are similar to converter’s rated parameters, it seems that there is a problem that SINAMICS DCM 6RA8013-6DV62-0AA0-Z converter has problems with motors which parameters are significantly smaller than rated parameters of this converter.

Maybe, problematic is too small values of armature and field currents. Maybe the currents are so small that they are discontinuous and this is a problem for the converter.

It seems to me that if the converter has the ability to reconfigure it to a motor with various parameters (even much smaller that the converter’s rated parameters), there should be a solution. What is more, since the SINAMICS DCM 6RA8013-6DV62-0AA0-Z is probably the smallest one of these types of converters produced by Siemens, so there should be any possibilities of adapting it to motors with various parameters.

I am asking you for help with this problem, because I really do not know how to deal with it. I have already asked many people, but no one knew how to help me.

Best regards,

Adam

Hello.

You should adapt rated converter armature and field currents as mentioned in the manual (e.g. page 286) and repeat optimization.

Thank you for you reply.

I did it as I mentioned at point number 1 of my thread.

Hello AdasK,

Sinamics DCM input supply voltage is 400 V AC. Motor armature rated voltage is 230 Volt AC. Now my questions are - 

1. How much AC input supply voltage is fed to drive? If it is 400 volt, drive performance will affect. It should be 200-230 V AC 3 phase.

2. Please set parameters p50067, p50076 & p50078 correctly (refer the attached sheet for information) re carry out optimisation & check.

HTH.

PISCEAN 2010, I am very grateful for your response.

That is true, the input voltage of the converter is 400 V AC, but the motor armature voltage is 230 V, bu tDC, not AC, because it is a DC motor.

1. I do not quite understand this question. The converter is supplied from 400 V AC 3 phase voltage source, but I do not know what part of this voltage is fed to the motor.

After all, there are two different circuits: the DC circuit at the inverter output and the AC circuit at inverter input.

1. This is very good remark and can be crucial in my problem. I have not done this what is in attachment. I have some questions about data in attachment.

"The rated armature DC current for the device must be adjusted by setting p50076 [0] (in%) or p50067 if:"

In the above excerpt,“The rated armature DC current for the device”refers to the rated current of the motor or converter?

"Maximum armature current <0.5 × rated armature DC current for the device"

I think that the left side refers to the motor and the right one refers to the converter, right?

So in my case for the armature, coefficient of reduction I calculate like fallows:

(2,6A / 15A) * 100% = 17.33%
And for the field:
(0.22 / 3A) * 100% = 7.33%

Do I understand correctly?

In parameter p50078 should I enter the converter’s supply voltage 400 V AC or I should enter there converter’s rated output parameters, which are the input parameters for the motor – I mean 420 V DC for the armature and 325 V DC for the field?

Maybe these are stupid questions, but I want to be sure if I understand everything In a right way.

AdasK

PISCEAN 2010, I am very grateful for your response.

That is true, the input voltage of the converter is 400 V AC, but the motor armature voltage is 230 V, bu tDC, not AC, because it is a DC motor.

1. I do not quite understand this question. The converter is supplied from 400 V AC 3 phase voltage source, but I do not know what part of this voltage is fed to the motor.

 Since your DC motor armature voltage is 230 volt, your DC converter AC side input supply should be 3 phase 230 volt AC & not 420 Volt AC. 

AdasK

"The rated armature DC current for the device must be adjusted by setting p50076 [0] (in%) or p50067 if:"

In the above excerpt,“The rated armature DC current for the device”refers to the rated current of the motor or converter?

Device = Converter & not motor

AdasK

"Maximum armature current <0.5 × rated armature DC current for the device"

I think that the left side refers to the motor and the right one refers to the converter, right?

So in my case for the armature, coefficient of reduction I calculate like fallows:

(2,6A / 15A) * 100% = 17.33%
And for the field:
(0.22 / 3A) * 100% = 7.33%

Do I understand correctly?

Yes correct.

AdasK

In parameter p50078 should I enter the converter’s supply voltage 400 V AC or I should enter there converter’s rated output parameters, which are the input parameters for the motor – I mean 420 V DC for the armature and 325 V DC for the field?

Maybe these are stupid questions, but I want to be sure if I understand everything In a right way.

If the converter connected input supply voltage for armature is 3 phase 400 volt AC then P50078[0] must be entered 400 & for field if connected supply voltage is 400 V AC then P50078[1] must be entered 400.

But to achieve better performance/speed regulation I suggest you to connect 3 phase 230 Volt AC supply to converet & set P50078 = 230 Volt.

HTH.

Thank you for your instructions!

Ehh… I have entered reduction coefficients, but after that the motor still worked badly. It seems like there is a slight, very slight improvement comparing to the previous situation, but the motor still does not work properly.

Moreover, after optimization process, the motor’s work became significantly worse. I observed that the motor’s speed was swaying and speed regulation became almost impossible, the motor could not reach constant value of speed.

I have no idea what is wrong with this all.

Maybe the problem is because of a way of speed measurement… maybe EMF estimation brings errors and maybe instead of that I should apply, for example a tachogenerator…

Hello,

How much AC input supply voltage to convereter? Please connect 230 Volt 3 Phase AC supply to convereter & then check. With 3 phase 400 V AC input supply you will not get better performance.

How much setpoint is applied to drive? Is it 0-10 volt or 4-20 mA?

How much is the value in p50104, p50106, p50108, p50115?

After entering motor parameter values, set p3900 = 3 i.e. quick commissioning, this will calculate motor data, then execute optimisation in your case conduct optimisation of EMF control i.e. p50051=27.

HTH.

PISCEAN 2010

Hello,

How much AC input supply voltage to convereter? Please connect 230 Volt 3 Phase AC supply to convereter & then check. With 3 phase 400 V AC input supply you will not get better performance.

 

The converter is connected to 3 phase 400 V AC and at present I do not have the possibility to connect it to 3 phase 230 V voltage source. So unfortunately, right now I have to deal with that voltage source, but in few weeks maybe I will have opportunity to change my voltage source - I need a transformer.

PISCEAN 2010

How much setpoint is applied to drive? Is it 0-10 volt or 4-20 mA?

Setpoint is applied by use of potentiometer. It is +/- 10 V

PISCEAN 2010

How much is the value in p50104, p50106, p50108, p50115?

The values in these parameters:

p50104=5000

p50106=5000

p50108=5000

p50115[0]=62,5

p50115[1]=100

p50115[2]=100

p50115[3]=100

PISCEAN 2010

After entering motor parameter values, set p3900 = 3 i.e. quick commissioning, this will calculate motor data, then execute optimisation in your case conduct optimisation of EMF control i.e. p50051=27

It is a great suggestion, because now I know that before I wrongly carried quick commissioning. After your suggestion, the parameters have different values than before and they are closer to the results of my measurements about which I metioned in my first message. And the motor works better but still not good enough.

I can not carry optimistation for p50051=25 because during this the motor rotates and I have to find a way to stop it from rotating, because when it rotates the calculated motor resistance has too high value - optimisation is not correct. After optimistaion motor works as badly as before.

Hello,

Till you get 3 phase 230 V AC supply try by following points.

1. Set p50104, 50106 & 50108 = 1500 RPM i.e. rated speed of motor. Please check other motor data values are correctly entered in appropriate parameters.

2. Set p50115 all indecses value = 100%

3. Set p2000 = 1500 rpm. It converts physical speed to relative speed, i.e. drive is informed the maximum speed of motor at 100% set point.

4. Set p3900 = 3 which will calculate motor data. This quick commissioning will calculate motor resistance.

5. If you have digital multimere, measure motor armature resistance, it would be 0.1xx ohm or compare it with the value calculated during quick commissioning. Try by manually entering armature resistance value p50110 [0] & conduct p50051 = 25 i.e. armature current control optimisation. If the performance is not smooth try by changing armature resistance values & conducting optimisation.

6. Then after conduct p50051 = 27 i.e. EMF control optimisation.

Please follow the sequence as mentioned above & check.