A 3-phase phase-locked loop diagram possible for an AC to DC battery charger? - Page 1
Forum section: electronics / general

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: August 17, 2021, 08:50:14 am
content: Hi there,In order to achieve unity power factor control, the phase of the AC voltage needs to be obtained. The phase is obtained through a phase-locked loop (PLL).Take a look for single phase control structure of the PLL ,Another might be understandableFor such similar way I want to mention some of 3-phase equations, could you kindly elaborate it more ?VSa = 1/3*(VSab-VSca);VSb = 1/3*(VSbc-VSab);VSc = 1/3*(VSca-VSbc);VSalpha = 2/3*(VSa - (0.5*VSb) - (0.5*VSc));VSbeta = 2/3 *(SQRT3_2*VSb - SQRT3_2*VSc);VSq = VSalpha*COS_theta + VSbeta*SIN_theta;VSd = -VSalpha*SIN_theta + VSbeta*COS_theta;VSd_error = (VSd - VSd_ref);freq_delta += (Kp_PLL*(VSd_error-AC_FREQ_PERR) + Ki_PLL*VSd_error);Kp_PLL=0.1p_VSd_error = VSd_error;if(freq_delta > 5.) freq_delta = 5.;if(freq_delta < -5.) freq_delta = -5.;freq = ((AC_FREQ_NORMAL ? 50 : 60) + freq_delta);freq_filtered = 0.99*freq_filtered + 0.01*freq;theta += (PI2*freq_filtered*AC_TSW);AC_TSW= 0.000033Lets angle theta goes pi to 2*pi.Kindly discuss logically.

author: Faringdon
author_rank: Super Contributor
timestamp: August 17, 2021, 06:34:50 pm
content: to get PFC with 3 phase, just use a 6 pulse rectifier...and it is a very well power factor corrected outcome for you.....use a low as possible capacitor after the 6 pulse rectifier.......Also, with 3 phase, you can use each phase separately and put each phase and neutral into an boost active pfc....if you want.For an active pfc (eg booster), you dont really need a PLL as such, you just "Look" at the rectified mains dc bus...and make the current follow it....then current is in phase with volts...and you have pfc...there are many chips that can do this for you......if you do it with a micro...you will probably just end up doing the same thing, with the same "modules", but with help from software.If you run a boost pfc chip in LTspice...eg, the LT1248, you will see how they work....you will find you do in software exactly what the LT1248 does,attached is a boost pfc with lt1248 in the free ltspice sim.....please run it, but it takes ages to settle out, as pfc has a slow feedback loop.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: August 18, 2021, 12:19:44 am
content: Dear Sir Faringdon,My best respect to you. Thank you for your response here.Lets put my feedback to youQuote.I think my system has leading PFC, because it does not have resistive load ( just when I test it with R), lets think battery works like a capacitor. Look at the datasheet of HF IGBT from infenon. I am using 6 pulses but with a different fashion.https://www.infineon.com/dgdl/Infineon-FF150R12RT4-DS-v02_01-EN.pdf?fileId=db3a304327b8975001280604608b6165For HF switching loss, spike or for other issue this IGBT module has small control circuit that has connection with DSP board.QuoteYes I did see such idea from some article, my case is little different. may be you are taking about this one사본 -Overall-circuit-configuration-of-the-universal-charger-with-the-signals-of-the-control.png