UCC28070: UCC28070: UCC28070 is not work

user5886207

Part Number: UCC28070

Hi team,

If Vin=0VAC, just through the partial voltage resistance Vsense=2V, Vinac=1V, it can be measured under the condition of maximum duty cycle drive waveform.

Vin=200VAC,and I test Vsense=2V，Vinac=2V，VAO=5V，Vss=6V,but there is no PWM, the chip startup conditions are met, why is it still not working?

		MIN	TYP	MAX	UNITS
Vin	RMS input voltage	176(Vin_min)		264(Vin_max)	V
Vout	output voltage		400		V
	Line frequency	47(f_line)		63	Hz
PF	Power factor at maximum load	0.9
Pout	Output power			3500	W
η	Full load efficiency	95%
Fs	Individual phase switching frequency		100		kHz

Is there something wrong with my parameter design?

Looking forward to your reply, thank you !

over 6 years ago

0 John Griffin1 over 6 years ago

TI__Mastermind 34465 points

Hello jiannan li
There is nothing wrong with your design parameters but without the full schematic I cannot really say why there is no pwm output.
Can you please post a pdf of the complete schematic as well as specifying the voltage on the VCC pin.

Regards
John

0 user5886207 over 6 years ago in reply to John Griffin1

Prodigy 95 points

1pfc.pdf

Hello John

Thank you for your reply. Here is my schematic. And VCC=15V

At last. May I have a Mathcad calculation for the UCC28070? Can you send it to my Email address 1197951995@qq.com

Regards

jiannanli

0 user5886207 over 6 years ago in reply to user5886207

Prodigy 95 points

Hello John

5722.ucc28070.pdf

300W28070.zip

I have some questions about Cta.Why are the formulas different.

data book

mathcad : 300WUCC28070 Design Tool

Regards

jiannanli

0 John Griffin1 over 6 years ago in reply to user5886207

TI__Mastermind 34465 points

Hello jiannanli,
There is an error in the Mathcad calculator.
The datasheet is correct.
CTA is a compensating capacitor and it should use the value of RTA in its calculation, not Rs( which is the CT burden resistor)
Thank you for finding this error.
Regards
John

0 user5886207 over 6 years ago in reply to John Griffin1

Prodigy 95 points

Hello John,

I recalculated the circuit around the UCC28070. Only the RA Rsyn RIMO Rzv Czv Cpv has been changed. And nothing else has been changed on the main circuit.

Vin=200VAC,and I test Vsense=2.07V，Vinac=2.08V，VAO=5.04V，Vss=6.17V. UCC28070 is still not working.

Here is my schematic and record.

Best Regards

jiannanli

experimentalrecord.doc

0 John Griffin1 over 6 years ago in reply to user5886207

TI__Mastermind 34465 points

Hi jiannanli,
The only other issues I can think of are:
(1) VCC is below the UVLO threshold.
(2) The UCC28070 is damaged and should be replaced.
If VINAC >0.7V and VSENSE > 0.75V you should be able to observe gate drive signals on GDA,GDB
Your system is set to run at 100kHz, 95% max duty cycle so this is the signal you should be seeing on GDA,GDB when its run open loop.
Double check your circuit that you do not have a short somewhere and replace the UCC28070 with the gates of the FETs disconnected.
Regards
John

0 John Griffin1 over 6 years ago in reply to John Griffin1

TI__Mastermind 34465 points

Hi jiannanli,,
I am going to close this thread since there has not been a new post or new information in almost 1 month.
Please open a new thread if you have further queries.
Regards
John

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UCC28070: UCC28070: UCC28070 is not work