TMS320F28069M: DC Voltage Offsets

Javier Vara

Part Number: TMS320F28069M

Hello,

I've noticed that when running the offset recalibration for the voltages at start-up those change with the value of the DC Bus Voltage applied (not like the current offsets which are constant). The inverter+motor pack that I am running is suppose to work with a big range of DC Bus voltages 200-700 V. Does this means that I have to run the offset recalibration every time I start up the inverter to acomodate for the different DC bus voltages? I would like to get rid of it to speed up the start-up time.

Kind regards,

Javier

over 6 years ago

0 Yanming Luo over 6 years ago

TI__Guru** 109740 points

You don't need to do the offset recalibration, you only need to do it when power up or before startup motor, even only do it one time for each different board. The DC voltage offset on every phase will be removed by transformation.

0 Javier Vara over 6 years ago in reply to Yanming Luo

Expert 1575 points

Thanks for the quick response.

In that case, do you recommend doing it at the nominal voltage or it doesn't make any difference at all?

0 Yanming Luo over 6 years ago in reply to Javier Vara

TI__Guru** 109740 points

It's better to do the calibration always in the background loop.

0 Javier Vara over 6 years ago in reply to Yanming Luo

Expert 1575 points

I'm sorry but I don't quite follow you.

I meant since running the offsets calibration is only necessary the first time, should I run it at the maximum voltage that I am going to run my inverter at or it doesn't make any difference?. On one hand I guess the higher the voltage the better resolution but on the other hand the lower the voltage the less noisy the measurement will be.

0 Yanming Luo over 6 years ago in reply to Javier Vara

TI__Guru** 109740 points

Not depends on voltage input, the voltage offset is just related to the voltage sampling circuit. You can do this voltage offset once when power on, or do this every times before startup the motor.

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TMS320F28069M: DC Voltage Offsets