TINA/Spice/UCC28C43: Simulation and model verification for UCC28C43

Ravi Chikkireddy54

Part Number: UCC28C43
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

A buck chopper is modelled in TINA software with UCC28C43. Power rating is 2.5kW. It has to operate from 65% duty to 96% duty @ 80 Hz. Model is successfully built to the requirements. Slope compensation parameters are calculated based on datasheet.

However, while testing the proto, results are not replicated to the simulation. We got sub-harmonic instability in the PWM output. We tried tuning every value of slope compensation parameters, didn't work. Current sensing is placed in switch path in beginning, now it changed to inductor path. Still, same result.

Output voltage voltage is regulated to the set value, throught the duty range, and response is smooth. No overshoots, no Undershoots.

I hope some of you can propose some clues/solution.

Thanks

Ravi

over 5 years ago

0 Manoj Toppalad over 5 years ago

TI__Prodigy 370 points

Hi Ravi,

Thanks For reaching us.
Could you please share the tina model which you are testing so that it helps us for better understanding?

Thanks,
Manoj T

0 Ravi Chikkireddy54 over 5 years ago in reply to Manoj Toppalad

Prodigy 40 points

Hi Manoj,

Attaching the TINA model, for buck chopper.

Thanks

RaviEVR_CS_mos_working 29-062018.TSC

0 Manoj Toppalad over 5 years ago in reply to Ravi Chikkireddy54

TI__Prodigy 370 points

HI Ravi,

Thanks for sharing the model. We will check and get back to you.

Thanks,
Manoj T

0 Manoj Toppalad over 5 years ago in reply to Manoj Toppalad

TI__Prodigy 370 points

Hi Ravi,

Just to confirm, the unstability in the PWM is seen in the EVM board results right?

Thanks,
Manoj T

0 Ravi Chikkireddy54 over 5 years ago in reply to Manoj Toppalad

Prodigy 40 points

Yes Manoj,

Sub-harmonic instability is observed in the Hardware testing, While simulation model is working fine.

Operating switching frequency is 80 kHz.

Thanks

Ravi

0 Ravi Chikkireddy54 over 5 years ago in reply to Ravi Chikkireddy54

Prodigy 40 points

Hey Manoj..

Any clues....?

0 Manoj Toppalad over 5 years ago in reply to Ravi Chikkireddy54

TI__Prodigy 370 points

Hi Ravi,

We are discussing with internal team. We will get back to you with the update.

Thanks,
Manoj T

0 Peter Meaney over 5 years ago in reply to Manoj Toppalad

TI__Mastermind 31580 points

Hi Ravi,

Have you measured the gain phase response of the hardware? It could be that some of the component values and parasitics are different in the hardware compared to the simulation.

Can you post some waveforms from the hardware, like the COMP pin voltage, CS pin Voltage.

What does the output voltage response look like during 25% to 100% load transient, it the response a single order recovery with no oscillation?

Regards

Peter

0 Herman Theodorus over 5 years ago in reply to Peter Meaney

TI__Genius 9775 points

Hi Ravi,

We have not heard from you for quite sometime. We assume somehow you have resolved the issue. I am going to close this post for now, but if you still need our help, please reply to Peter's and/or Manoj's inquiry so that they can assist you further.

Herman

Simulation, hardware & system design tools

Simulation, hardware & system design tools forum

TINA/Spice/UCC28C43: Simulation and model verification for UCC28C43