f28379 - Reference Generator

Hi,

I want to implement a VF converter and I need 3 sine wave and a triangle wave references. I accomplished this with the blocks (file attached to this post). But the problem is resolution and frequencies become worse and wors with time.

I want the carrier (triangle) wave to be 1KHz and sinus 50Hz. At start everthing seems OK. But later Sinus drops down to 40-30 and later 13Hz. Resolution becomes unacceptable. Triangle becomes much worse.

Reference amplitudes conditioned for DAC output which I observe DAC with oscillascope.

If I increase Samples per perdiod etc Launchpad stops working. 50Hz for sine, 1KHz for triangle is best I can get and even these are not enough for project.

Matlab 2018b - Launchpad F28379D

Note : I tried - " boot from flash enabled/disabled " doesn't work. Also program doesn't run on external mode.

[Venkatesh Chilapur]

Hi,

Can you check if the sample time (step rate) is too quick for the computation to complete. This could be an overrun situation. Try reducing the sample time and see if that gives better results.

The "sin" block in Simulink is not optimized for embedded controllers which could be the reason for it to be not working as expected.

However we could use "CLAsin" function as provided by TI in the form of library that we can use inside CLA for sin calculations. These sin values can later be transformed into digital counts as required by ePWM or DAC module to generate the sin wave.

HTH,

Venkatesh C