TMS320F28335: Variation in 3 Phase SPLL output

Manish Girase

Part Number: TMS320F28335

Dear Sir,

Thanks for your support. While implementing 3 phase SPLL on TMS320f28335 I am getting large variation in F0 output of SPLL. The variation is from 55 hz to 45 hz.

Attaching screen shot for your reference . Please suggest what will be the cause.for such variation. Ihave stored samples for input ac signal and SPLL output. Attached photograph showing

PWM output following the Theta from SPLL and the AC input volatge.

SPLL 3phase f0 output variation.docx

over 5 years ago

0 Manish Bhardwaj over 5 years ago

TI__Mastermind 43730 points

Manish,

Some oscillation is expected, for example in my experiments i get 1-2 Hz of variation

Exact variation you get may depend on the noise and the ISR rate etc,

Typically people use a LPF on the SPLL.fo to get a stable reading on it.

0 Manish Girase over 5 years ago in reply to Manish Bhardwaj

Intellectual 360 points

Thanks for reply.it is in line with my understanding only the variation was too high so get confused . I will improve it now. Thanks for your support.

Manish Girase.

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TMS320F28335: Variation in 3 Phase SPLL output