PWM Control for DC to Three Phase AC Inverter

[G.Norris]

Hello.

I am trying to make programme to produce PWM control signals, to operate a simple DC-to-3phaseAC inverter for an output frequency of 50Hz. The following programme I have created only really works when the output is chosen to be 1Hz. Even then the output is messy.

I know this is because the sine control signal and triangle signal become greatly distorted as their frequencies are increased.

From my ‘newbie’ eye and the hours of research I have conducted before deciding to post this, I believe it is something to do with the sampling.

I was wondering how I went about changing the sampling of the SineWavePtByPt and the TriangleWavePtByPt?

Or failing that how I could make this programme work with an output of 50Hz?

Thanks in advance. Apologies if this is a very silly question, I am very new to LabView and am having to use it to complete a project with a tight deadline.

[G.Norris]

Hi all,

Just wondered if anyone had any ideas?

Thanks again!

[Vsenior]

Hi G.Norris, 

I'm an applications Engineer from NI and I've take a look at your code. I guess the first thing I need to ask is with this code is what you mean when you say the output is "messy"? Do you mean that what's showing up on the graphs in the code is messy? Or are we talking about what you're outputting to your digital lines? Are you monitoring thise externally and this is where the code is not doing what you expect? Also, can you tell me what you mean by messy?

You also talk about the sampling of the Sinewave/trianglewave point by point VIs, however these VIs only generate a single data point at a time, so they don't have a sampling rate. Could you clarify what you mean by this?

Kind regards

Vivien