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Start a SimulationCRD22-AD12N_22KW firmware epwm setup for low-side switch
Dear sir/madam,
Recently we requested the firmware for the CRD-22AD12N.
Our goal is to design a 3 phase PFC based on this design.
In the schematics I can see that EPWM10, EPWM11 and EPWM12 are used for switching the 6 FETs of the PFC (Q7, Q8, Q9, Q10, Q11, Q12).
What I can see in firmware is that EPWM10, EPWM11 and EPWM12 are setup in function InitEPWM(void).
The dutycycle on the high side FETS (Q7, Q8, Q9) is adjusted by changing the CMPA value of these 3 pwm-modules in interrupt function Epwm11_Isr (void)
I cannot find the part in the firmware where the B-channels of EPWM10B, EPWM11B and EPWM12B are setup and adjusted to switch Q10, Q11 and Q12.
- In 3 phase PFC mode, it seems that the B-channels are not used, the FETs Q10, Q11 and Q12 are always switched off. Is this correct?
- And if not, could you point to me where in the firmware these B-channels are setup and adjusted?
- What are EPWM modules 1 till 8 used for?
Regards,
Remco
Comments
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Thank you for your post, it has been approved and we will respond as soon as possible.
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Found the answer on question 1 and 2.
By setting up a deadband for EPWM10, EPWM11 and EPWM12 the pwm outputs A and B automatically work together (inverted). Therefor only CMPA has to be set to adjust the dutycycle of both outputs.
Question 3 remains.
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The answer for Question 3.
The EPWM modules 1 till 8 are not used, they are reserved for driving the DC/DC (CLLC ) stage. You can ignore the EPWM1~8 related source code in this application.
