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Hello,
I'm using MATLAB Simulink with the "Embedded Coder Support Package for Texas Instruments C2000 Processors" Addon.
I want to create 6 PWM- Signals for an Dual Active Bridge DC/DC-Converter. These 6 PWM- Signals must be phase shifted to each other.
PWM 1 is the Master for the synchronization.
PWM 2 should shifted 120°
PWM 3 240°
PWM 4 in phase to PWM 1 + PHI
PWM 5 120°+ PHI
PWM 6 240°+ PHI
PHI is going from -90° to +90°
Now my Problem is that the ePWM function block don't allow a negative phase value.
So I tried to shift with (360°-PHI) that didn't work too.
When I shift an PWM-Signal more than 270°, I didn't get any PWM signal from that Port.
Here is my Network-construction:
555 is the Clock cycle.
That's around 180k Hz.
What can I do to achieve an negative Phase shift from -90° -0°
Hi,
The ePWM block expects the phase value in the range of 0 to 360 deg values scaled with clock cycles as input to the phase values. Hence for the negative values you need to add 360 deg to bring it to the range of 0 to 360 deg phase.
1) For -90 deg value, you will have to provide (360 - 90) = 270 deg as input.
2) For any values greater than 360 deg you need to consider the logic to wrap the value to the scale of 0 to 360 deg. For example, 120 + (360 - 90) = 390 should be wrapped as (390 - 360) = 30 deg before scaling it with clock cycles and providing it as input to ePWM.
Here is a screen shot of the model with PHI value set to -90 deg for the ePWM network similar to one described above.
Hope it helps.
Thanks,
Aditya Padmanabha
MathWorks
