Generating pulse width modulation gates

In my attempts to model a spatial vector pwm system with FOC, I have been running into problems obtaining the proper gate responses. They appear similar to delta functions (they have almost no time width) so there must be a problem with my comparison between on-times for a, b, and c phases with the repeating sequence block.

I attached my model here. I believe that the Clarke and Park transformations are accurate, but I am not well-versed with the repeating sequence block and the simscape electrical permanent magnet synchronous machine component. The SVPWM subsystem contains the gate calculation subsystem which does not seem output correctly.

I would deeply appreciate any help because I have read every online example that I can find. Thank you so much!

Answer 1

[Joel Van Sickel]

Hello Nate,

You can use a repeating sequence to generate your carrier wave. It looks like that is what you are trying to do. If you have simscape electrical installed, you don't need to do this from scratch.

Have you seen this example: https://www.mathworks.com/matlabcentral/answers/579837-generating-pulse-width-modulation-gates?s_tid=srchtitle

You can right click this block and choose look under mask, to view the different subsystems and see how the logic is implemented. There are various ways to generate PWM signals using simulink blocks. You can also use some of the prepackaged PWM generators instead of building your own. You can also explore how they were implemented.

https://www.mathworks.com/help/physmod/sps/ref/pwmgeneratorthreephasetwolevel.html

the block above can be selected to use SVM.

For your model, typically for generating PWM waves, you would want to compaire your values to the carrier wave. Instead of adding values to the repeating sequence and passing them through a relay, it might be more intutive to start with the 'relational operator' block to generate the PWM signals.

Regards,

Joel

[An]

Hello!

Unfortunately I have similar problem with pulse generation. I use 2-level PWM generator (https://se.mathworks.com/help/physmod/sps/powersys/ref/pwmgenerator2level.html) for three-phase converter with IGBTs (universal bridge). After appliying three-phase sinusoidal reference voltage to pulse generator, I receive pulses but going to the converter the three-phase sinusoidal waveform becomes similar to pulses, also the DC voltage is not contant at all. What might cause that mistake?

My question is here:

https://se.mathworks.com/matlabcentral/answers/583262-mistake-with-pwm-generation-using-simulink?s_tid=prof_contriblnk