TMDSCNCD28388D: Generate a sinusoidal modulated PWM

Gianluca Di Pietro

Part Number: TMDSCNCD28388D

Tool/software:

Hello everyone, i aim to generate a sinusoidal pwm modulation, i have readen the manuals about how to generate a simple pwm with desired frequency and duty cycle and it works. Now i want a pwm modulated by a sine wave of 50 Hz, given my carrier frequency signal at 10 kHz. My board is the F28388D. How is possible to correctly write a sin wave of 50Hz?What are the logical steps i have to follow ? i have generated interrupts and also ISR, in my case i will have 2 interrupts for each period of my carrier signal, one interrupt on 0 and another on PRD,using a counter in up-down mode.How should be choosen the angle or the time step of the sine wave in order to generate a 50Hz wave given these carrier signal features? thanks in advice

1 month ago

0 Sumit Patil1 1 month ago

TI__Intellectual 1880 points

Gianluca,

Have you checked the reference design code for voltage source inverter: https://www.ti.com/tool/TIDM-HV-1PH-DCAC

You can check the source code documentation with user guide here: https://software-dl.ti.com/C2000/c2000_apps_public_sw/c2000ware_sdk/digitalpowersdk/5_03_00_00/html_guide/TIDM-HV-1PH-DCAC.html

In short, in this code the methodology used is:

1. Create per unit sawtooth ramp using ramp generator with RAMPGEN library

2. Multiply that instantaneos value of ramp with 2*pi and feed that value Sine function.

This will generate per unit sinusoidal reference. Following is snippet from "voltagesourceinvlcfltr.c" file from the project "voltageSourceInverter"

Following is snap of "rampgen.h" for the the function definition to generate the ramp: https://software-dl.ti.com/C2000/c2000_apps_public_sw/c2000ware_sdk/digitalpowersdk/5_03_00_00/html_guide/group__RAMPGEN.html

3. Feed that value to duty component of you current code which will eventually go to CMPA of ePWM

Please see the following diagram from user guide:https://www.ti.com/lit/ug/tiduay6e/tiduay6e.pdf

Let me know if any further questions.

Regards,

Sumit

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMDSCNCD28388D: Generate a sinusoidal modulated PWM