Variable Frequency Drive Simulation in Multisim 11
I'm having trouble creating a VFD simulation on Multisim 11. I've created a Delta source connected to a 6-pulse rectifier, which connects to a filter, which connects to a PWM (antiparallel SCRs), which connects to my motor.
Any corrections to be made? Additions? Thanks.
Just an update for the community. In version 12 we have added a lot more components into the Electro_Mechancal family which can really enable users to further their testing abilities.
Co-Simulation is also a very revolutionary feature that has been added to Multisim to allow users to test a complete system by being able to test their circuits along side their LabVIEW code.
Regards,
Tayyab R,
National Instruments.
Similar Messages
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Variable frequency driver control by analog voltage output
I need to drive a variable frequency inverter to drive a compressor and I am too newbie in this kind of works. The inverter can be controlled by analog voltage input and I have NI9188 and NI9263. I have never used analog output modules before and I have some doubts about them.
1. how could I drive the motor continuously?
2. do I have to use device internal clock or software clock?
3. in some examples, a waveform is generated and sent to the write daqmx vi to generate analog output. do I need to do it? (By the way, I prepared a control subVI to send the required input voltage data to the write daqmx.)
4. It is talked about pulse with modulation sth like that. What is it exactly? Do I need to concern about it?
I need to drive the compressor with two temperature feedback so I prepared a huge program by master/slave design pattern. I attached it. Does this program work? I do not want to harm the motor so I could not test it.
Egemen
Attachments:
Control Project.v0.zip 2672 KBHi newbieeng,
I hope you are doing well today! I can help answer questions, but I can't debug a program and say whether it will work or not.
A lot of these question depend on your specific application and can't be answered in general. I would take a look at the specifications document for the NI 9263 and also the specifications for your motor. I'm including a link below to the specifications document for the NI 9263. I would highly recommend looking at the current draw of the motor. The most the NI 9263 can drive is 1 mA per channel.
OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9263
http://www.ni.com/pdf/manuals/373781e.pdf
As far as hardware timing vs. software timing, it really depends on what you want to do. Hardware timing provides most more precise control over the timing of the output.
From one of the subVIs you provided, there seems to be a mention of a relationship between frequency and RPM. Is this representative of a control signal the motor expects? Is this the pulse width modulation (PWM) you were talking about? If your motor requires PWM, then you will need to send it the appropriate signals. I'm attaching a link below to an example regarding PWM.
Pulse Width Modulation
https://decibel.ni.com/content/docs/DOC-17537
Hopefully some of this is helpful!
Josh B
Applications Engineer
National Instruments -
Frequency Modulation circuit simulation in Multisim Using 566.
How can I get Frequency Modulation circuit simulation in Multisim Using 566? In Multisim I dont have IC 566.. And I have attached the image of the circuit i want... I dont want to use FM signal source directly.
Attachments:
FM CIRCUIT USING IC566.PNG 21 KBHello,
This component is not available in Multisim; I tried to locate a SPICE model for LM566 with no luck. It seems that the component is obsolete now.
Take a look of this old forum post, it explains an alternate method to build the FM circuit.
Hope this helps.
Fernando D.
National Instruments -
Hi everyone,
I wrote a Labview Instrument VI that I use later in my simulation in Multisim. The problem is, after stopping the simulation and restarting it again, some important parameters of the VI are not initialized again and therefore all my calculations in the Labview Instrument file are messed up.
Is there any option to set the params back to their default values after the simulation has been restarted?
Has that something to do with Serialize/Deserialize Data in the VI?
Thanks in advance!
Ussr123ussr123 wrote:
The problem is, after stopping the simulation and restarting it again, some important parameters of the VI are not initialized again and therefore all my calculations in the Labview Instrument file are messed up.
Is there any option to set the params back to their default values after the simulation has been restarted?
Where is the data held inside the LabVIEW code (local variables, uninitialized shift registers, etc.)?
LabVIEW Champion . Do more with less code and in less time . -
Continous sound output with variable frequency?
Hi all!
I wanted to output a signal via the soundcard with one variable frequency.
How can I do that?
Thanks
ANDYHi Andy
I'm afraid I've only got access to 7.0 & 7.1.
SO Set Num Buffers.vi uses a Call Library Function node to access lvsound.dll.
Hmmm...
I've had a scan around and you could try checking this link
It may give you some clues.
Good luck
Neil -
Hi,I want to replace a LM3905N with a similar IC (same pin-config.) for simulation in multisim.Have you any suggestion?Cordially,Richard
Hi e00ricaCuba
I can't really suggest anything to you from the top of my head. Have you tried checking with the manufactorer of the IC? For the LM3905N I belive National Semiconductors is the manufactorer.
Best Regards
David
NISW -
Has anyone used Labview to communicate over usb (or RS232/RS485) with an Danfoss VLT AutomationDrive FC 302 adjustable frequency drive ?
Thanks
HierromovilDuplicate - http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/Labview-to-communicate-over-usb-with-a-Danfos...
-
Labview to communicate over usb with a Danfoss VLT AutomationDrive FC 302 adjustable frequency drive
Has anyone used Labview to communicate over usb (or RS232/RS485) with a Danfoss VLT AutomationDrive FC 302 adjustable frequency drive ?
Thanks
HierromovilHello there;
Please don't post the same question twice, it makes it harder to keep track of the answers
Duplicate post.
http://forums.ni.com/t5/LabVIEW/I-need-a-VI-for-a-speed-driver-Danfoss/m-p/3116579#M894304
Greetings -
Unexpected reboot during simulation using multisim on AMD dual core processor
We are using NI-multisim 10 in a classroom environment and are experiencing sudden reboots during simulation without giving any error or warning. This happens on multiple machines, all being Dell Optiplex 740 with AMD DC 2Ghz as processor. Since these problems happen so frequently, making teaching quite impossible, we have shifted PC-room and are now using older machines. On these machines - Dell GX280 using intell P4HT-2,8 Ghz - we experience no more problems.
Is this reboot problem related to the article : Unexpected Errors with DAQ Device on AMD Dual Core Machine (http://digital.ni.com/public.nsf/allkb/9CE22FE099AFB8BF862572FF007A5D45) and what do we have to do to fix this problem?Nic
Can you verify your driver versions? Make sure that you are running the latest versions of NI drivers to ensure proper compatibility. If possible, you might try upgrading to multisim 11. If this does not solve the issue, try the single processor workaround in outlined in the following KB:
http://digital.ni.com/public.nsf/allkb/D0FC3BE7D9F331398625731A005D76B8?OpenDocument
Altough it is surely decreasing the performance of the system, certain cases have shown that there is no other possible workaround unfortunately.
Best Regards
Michiel
Applications Engineer
NI Belgium
http://www.ni.com/ask -
Better estimation of phase difference between two signals with variable frequency!
Hello LabView Gurus,
Being a power engineer and having just a little knowledge of signal processing and labview, I have been pulling my hair out for the last couple of days to get a better estimation of phase difference between two signals.
We have two analog voltage signals; 1. sine wave (50Hz ± 1Hz) and 2. a square wave with exactly half of sine wave frequency at any time.
At the starting point of operation (and simulation/acquisition) both signals will have no phase difference. However, the square wave's frequency changes unpredictably for a just a few millisecond but then it gets synchronized with sine wave's frequency again. This means that the square wave will be phased out from its original position. The task of the labview is to find the phase difference between the two signals continuously.
My approach to determine the phase difference is to measure the time when sine wave crosses zero amplitude and the time when the very next square wave changes amplitude from zero volts to +ve voltage (I have a 0.5volts threshold just to avoid any dramas from small line noise). The difference between these times is then divided by the time period and multiplied by 360 to get this phase difference in angles.
As this part is just a small block of a big project, I can only allow 5000Hz sampling rate each for both signals. I read 500 samples (which means I read data from 5 cycles of sine wave and 2.5 cycles of square wave).
Now the problem is, as long as the frequency of sine wave stays constant at exactly 50Hz, I get a good estimation of the phase difference but when the frequency changes even a little (and it will happen in the real scenario i.e 50Hz ± 1Hz and the square wave's frequency is dependent of sine wave's frequency), the estimation error increases.
I have attached my labview program. From front panel, you can set the phase of square wave (between -180 and 0) and you should see the labview's calculated phase in the indicator box named 'Phase'. Then you can press 'Real Frequency' switch that would cause the frequency to change like it would in real operation.
You can observe that the estimation error increases after you push the button.
All I need to do is to reduce this estimation error and make it as close to the actual phase difference as possible. Any help would be greatly appreciated.
I am using LabView 2009 for this task.
The application is for electric machines and the stability/performance of machines under different faults.
Thank you for reading this far!
Regards,
Awais
Attachments:
v603.png 320 KB
v603.vi 186 KBJeff Bohrer wrote:
Basic math gives me a bit of pause on this approach. You are sampling at 50 times the frequency of interest so you get 50 samples per cycle. your phase resolution is 1/50th cycle or 7.2 degrees +/- noise. You will need to samlpe faster to reduce phase resolution or average multiple readings (at a time cost that is signifigant)
Jeff- (Hardly Working)
I am sampling at 100 times the sine wave's frequency and 200 times the square wave's frequency. Increasing the sampling rate completely solves my problem. But since I am acquiring several other inputs, I cannot afford a sampling rate higher than 5kHz.
F. Schubert wrote:
I'm not a signal processing expert, but here my basic understanding.
If you simulate sampling with 5kHz and a frequency of 50 Hz (and both are 'sync' by design), you always get an exact 5 periods. Any variation of your signals frequency gives you a propability to get 4 or 6 'trigger' events. That's an up or down of 20%!
The one measure to reduce such problems is using 'window functions'. They don't fit your current approach (counting instead of a DSP algorithm), so this needs to be reworked as well.
My approach would be to use the concept of a Locki-In amplifier. You need to phaseshift your ref-signal by 90°. Then multiply your measurement signal with the ref signal and the phase shifted ref signal. The obtained values for x/y coordinates of a complex number. Calculate the theta of the complex number (with the LV prim). Feed this in a low pass filter.
The trick on this is, that the square wave has harmonics in it, in this you are interested in the second harmonic which is the sine wave.
To get rid of the effect that the sync between sampling rate and ref signal frequency gives an error, you then can use the window I mentioned above (place it before the lock-in).
For a design that really plays well, use a producer-consumer design pattern to get the calculations done in parallel with the DAQ.
I suggest you to check on wikipedia for some of the keywords I mentioned. Go also for the external links which lead to great tutorials and AppNotes on the signal processing basics.
Sorry, it's not a simple solution I offer and we will have quite some conversation on this forum if you follow this path. Maybe someone else knows a simpler way.
Felix
www.aescusoft.de
My latest community nugget on producer/consumer design
My current blog: A journey through uml
An interesting view. the sine wave can indeed be looked as a second harmonic of the square wave. I will implement your idea and get back to you as soon as I get some results. But since I have very limited knowledge of signal processing, it might take me a while to get my hear around the solution you mentioned. -
Displaying a simulation from Multisim 12 in labview11
Hi admin, I simulate a circuit with Multisim, it works well, I got mysignal, I still aqueillir that this signal by labview, I install the toolkit, I plugged the connector, I found no evidence for labview multisim12 in2011, how do?
Solved!
Go to Solution.Hi,
I am not sure what your issue is. Please take a look in the link below. It shows you what you need to be able to use Co-simulation.
http://zone.ni.com/devzone/cda/tut/p/id/13663
Hope this helps.
Regards,
Tayyab R,
National Instruments. -
Audio sample at variable frequency
I think this is the right forum for that question.<BR>
Do anyone know if it is possible to play an audio sample an modify the frequency while playing according to a variable value?
Any example?write yourself a Mixer that can change the frequency of the data flowing through it.</p>
Mixer
<p>
Or find one on the internet that does it.
<p>
matfud -
Hello,
I've circuit based on 555 timer which should generate 40kHz (50% DC) square wave.
But Multisim simulate 26.367 Khz only.
Circuit calculated by "Tools/Circuit Wizard/555 Timer Wizard/" and verified with datasheet.
This circuit assemblied on real maket board and works fine.
Multisim version is 10.1.1
So, what's wrong here?
Thanks,
Sergey
Solved!
Go to Solution.Hi,
I built the circuit using the shown component values and I was able to get the circuit to produce the right reading by changing the time step(TMAX) from 1e-5sec to 1e-8 sec, this setting is under Simulate>>Interactive Simulation settings. By reducing the time step you are telling the simulator to take more samples and gave and more accurate reading.
Tien P.
National Instruments
Attachments:
Timer.ms10 92 KB -
How can I generate variable frequency in different time with NI USB 6229?!
Hello,
I have NI USB 6229, and I want to have VI which;
in this VI I have to firstly generate a initial frequency togive it to a circuit, after that according to the results that I am reading from circuit I have to make some delay in the same frequency which I generated before and again give it to circuit to see the results again.actually in other word it is some kind of feedback process.
I would be thankful if some one can help me to how to make this VI because still I do not have any idea to program it.
Sorry if I could not explain well because I am as beginner .
thanksHi worldviol
I think a great place to start would be for you to have a look at the examples included in LabVIEW (help >> Find Examples..)
Have a look under 'Hardware Input and Output' > 'DAQmx' and then 'Analog Input' and 'Analog Output' you will also probably find 'Synchronization' useful.
The next stage would be to pick the most appropriate design pattern, you should read the white-paper here on design patterns.
I think the producer consumer design pattern would be useful here as you would be reading and writing to the device at different rates.
Kind Regards
Chris | Applications Engineer NIUK -
How to continuously generate a pulse train with variable frequency
Dear all,
I am trying to use NI-USB 6259(BNC) to send Pulse signals to conduct position control of a servo motor with labview. The position control of servo motor follows these rules:
The number of the pulse train determines how many degrees the motor rotate ;( e.g. the angular position of motor)
The frequency of pulses determines how fast the motor rotate; (e.g. the speed of motor rotating)
The digital determines the direction of rotation of motor (e.g. clockwise or counterclockwise)
My question comes when I need to continuously generate a finite plus train signal in a period of time. Below is a sample:
Time(s)
Number of pulses
Direction of rotation
(1 is clockwise, 0 is counterclockwise)
Frequency
0-1
923
1
923hz
1-2
3540
0
3540hz
2-3
1751
1
1751hz
3-4
2663
0
2663hz
4-5
353
0
353hz
5-6
1017
1
1017hz
6-7
3436
1
3436hz
7-8
302
0
302hz
8-9
1513
1
1513hz
9-10
570
1
570hz
Here is the explanation of this table, the motor keeps rotating in clockwise direction during 0~1s. When the time reaches 1s, the motor just complete the rotation of 923 pulse signals. And then the motor starts to rotate in counterclockwise direction during 1s~2s. When the time reaches 2s, the motor just complete the rotation of 3540 pulse signals. So we can see that the rotating speed of motor in 0~1s is different from the speed in 1s~2s. Namely, the frequency of pulse signal in 0~1s is different from the frequency in 1s~2s.
I have already use the counter output of DAQmx, it just can generate pulse signal with certain numbers and certain frequency in one time. The attachment is the vi which can generate a finite digital pulse train from a counter output channel and the frequency, duty cycle, Initial delay, and Idle state are all configurable.
How can I continuously generate a series of pulse train with varying numbers and frequencies during a certain period of time.
Thank you very much for your help!
Solved!
Go to Solution.
Attachments:
Counter - Finite Output.vi 57 KB
Finite output.png 13 KBHi aacuna,
Thank you for your reply!
I already checked that article. The frequency in that Vi can change dynamically, but the method of adjusting the frequency is ‘manual’ .Below is the front panel of that Vi. When the Vi is running we can change the frequency by press the button.
Time(s)
Frequency
0-1
923hz
1-2
3540hz
2-3
1751hz
3-4
2663hz
4-5
353hz
5-6
1017hz
6-7
3436hz
7-8
302hz
8-9
1513hz
9-10
570hz
Thank you!
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