generating synchro/resolver signals using NI 9269

[Tirmizi]

can you explain what do you mean by "except the hardware will not produce the amplitude of your signal." as writte in your post.

second software has an amplitude factor that can be used with external voltage amplifier to acheive the required physical voltage levels. 

is there is any particualr equation through which give me the req physical voltage levels by using software amplitude factor and external voltage amplifier

i wiill generate these signals from NI 9269 and apply them on an angle position indicator (API). if the hardwre will not produce amplitude what is needed then API will not show correct angle which i want to transmitt.

Best Regards

[srm@viewpointusa.com]

the NI 9269 has +-10V output range.  by your information, it looks like you want to produce sqrt(2)*11.8 or ~+-17V.

you can not get 17V from a 10V device.

Therefore you will need an additional device to amplify the voltage signal from the NI 9269 by approximately 2.  if you use this gain device, then you would specify an amplitude of 8.5 in the fpga code i supplied because 8.5*2 is 17.  the actual software factor would be adjusted as appropriate depending on how exact a final amplitude you need.

BTW, the angle would still be correct and most resolver decoding schemes would still produce the correct angle but would fail an amplitude check in this case without the extra gain stage.

[Tirmizi]

i have one query regarding synchros, are S1,S2 and S3 are 120 degree phase shift, i mean that phase diff between S1 and S2 is 120 and between S2 and S3 is 120

  if this is so then i have to use three sinewave generators and from parameter settings make phase=0, phase=120 and phase=240.

i am confusing between phase shift as discussed above and theta+60 or 120 for amplitude levels calc of each synchro signal which use following formula

S1= - sqrt (2) * (11.8)* sin (theta + 60) * sin(wt)  eq (1)  

S2= - sqrt (2) * (11.8) * sin (theta) * sin (wt)       eq(2)

S3= - sqrt (2) * (11.8)* sin (theta + 120) * sin(wt)     eq (3)

[srm@viewpointusa.com]

do you mean that 

S1= - sqrt (2) * (11.8)* sin (theta + 60) * sin(wt)  eq (1)  

S2= - sqrt (2) * (11.8) * sin (theta) * sin (wt+120)       eq(2)

S3= - sqrt (2) * (11.8)* sin (theta + 120) * sin(wt+240)     eq (3)

?

if so, this is still one generator with each phase offset as an addition similar to the way theta+120 was generated.

as long as the addition is configured for the right output fixed point type with wrap enabled, it is fine.

it is usually beneficial to generate the waveforms in high level labview or matlab to get a visual of the waveforms you are generating in the time domain.  then test your FPGA code to verify it is producing the right waveforms.

[Tirmizi]

i have generated the synchro signals from fpga using your modified vi. and watch it on oscilliscope. the instruaments i use for this experiment are synchro Ref voltage supply and  a CSI synchro meter whcih has a range for Ref input voltage starting from 20 V and synchro  voltage range starting from 7 volts. i have first followed following equations.

S1=  K* sin (theta + 60) * sin(wt)  eq (1)  

S2=  K * sin (theta) * sin (wt)       eq(2)

S3= K* (11.8)* sin (theta + 120) * sin(wt)     eq (3)

where K is a constant value set by the 'amplitude' control variable present in your vi. as i change the amplitude value the amplitude of synchro signals changed. however S1,S2,S3 are all aligned means no phase difference.but when i read the reading on CSI meter it is wierd like 200 then 190, 180, 100, ...4,5 ..0 and then go to 300 something. i am not getting the right value whcih i set i.e 15 degree (0.834 pi radians). why it is happening so i dont understand

since My DAC limit as you know is +-10 volts so i choose the ref voltage be 20 volts rms 400Hz

I

My second issue is that i read from public domain that synchros have a transformation ratio (T.R) which is

  TR = Vout / Vin       so for 26 Vrms Ref input and desired output of 11.8 Vrms TR = 11.8 / 26  = 0.45....

in my experiment  for Ref input of 20 volts and desired synchro output of 7 V rms , T.R = 7 / 20 =0.35

now the problem is how to set my amplitude value according to theT.R value so that required amplitude get genrated and i get the correct synchro angle on CSI meter which is 15 degree (  0.0834 pi radians).

[srm@viewpointusa.com]

you are flying all over the place here.

are you doing resolver simulation and have an external excitation signal?

are you simulating both the excitation and response signals?

i have not seen a resolver with three outputs.  the typical resolver has two outputs, sin and cos of the resolver angle.

can you post a graph of the desired waveforms that match the math you have posted?

[Tirmizi]

sorry for the subject of my post  "generating synchro/resolver  signals using NI 9269" whcih mentioned reoslver word , i mainly focus my self towards synchros at this moment. see my posts in whcih i try to simulate synchro signals using 9269 not resolver.

[Tirmizi]

i followed the equations i wrote in my first post , but when i run the program and watch the CSI meter the value is wierd means instead of giving angle value of 15 degree it shows 200, or 118 , 80 and the values keep on fluctuating.

uptill now i have generated the 400Hz sinewaves but cannot fix for the proper software amplitude factor as i dont know the valid formula which give me the software amplitude factor value for a particular synchro design.

[kuttan.ch]

can you suggest how to generate 26v 400 hz for synchro reference voltage .it should be simple to build circuit