Danfoss TTS350

4.24 High Voltage DC-DC Converter
Therearetwo(2)variantsoftheDC-DCConvertermentionedinthismanual.Thereisanepoxy,pottedstylewhich
wasinproductionsincecompressorinceptionandthereistheopenframeDC-DCconverterthatwasreleasedto
productionasreplacementofthepottedstyleinApril2019.Theremovalandinstallationofthetwo(2)variantsare
verysimilar.Theopenframestyleutilizessix(6)mountingfastenerswhilethepottedstyleuseseight(8).Theopen-
framestyleutilizesthree(3)connectorswhereasthepottedstyleusesfour(4).Theopenframedesignnolonger
usesthe15VACtriggersignalfromtheSoftStart,thuseliminatingtheneedfor15VAContheDC-DC.
TheopenframeDC-DCConverterisfullybackwardscompatible,anditworkswithallofthevoltageapplications.
ThepottedDC-DCConverterisspecifictoagivenvoltage.
4.24.1 DC-DC Converter Function
TheDC-DCConverterprovidestheBackplanewith+24VDC(withrespectto0V)andHV+(+250VDCwithrespectto
HV-)fortheBearingPWMAmplifier.
DCbusvoltage(460-900VDC)issuppliedtothePottedDC-DCconverterthroughtheClosed-TopSoftStartBoardF1
fuse.DCbusvoltage(460-900VDC)issuppliedtotheOpenFrameDC-DCconverterdirectlythroughtheAC/DC
harness.
TheClosed-TopSoftStartBoardalsopowersthepotted-styleDC-DCConverterwith15VACwhentheDCbushas
reachedminimumlevel.
RefertoFigure4-229PottedDC-DConpage206andFigure4-230OpenFrameDC-DConpage206fortheDC-DC
Converterinput-output(I/O)connections:
Inputs:
l
J1BusInput
l
J415VAC(pottedversiononly)
Outputs:
l
J2250VDC
l
J324VDC(potted)J424VDC(openframe)
4.24.2 DC-DC Converter Verification

4.24.2.1 Input Voltage Verification
1. IsolatethecompressorpowerasdescribedinSection1.8ElectricalIsolationonpage22.
2. InstalltheDCbustestharness.RefertoSection1.10.1GeneralVerificationandInstallationoftheDC
BusTestHarnessonpage26.
3. Turnonthemainspowertothecompressor.
4. UsingtheDCbustestharness,verifytheexpectedvoltagesarepresent.RefertoTable4-18Expected
ACVoltageRangeonpage102.
4.24.2.2 Output Voltage Verification
1. RemovetheServiceSideCover.RefertoSection4.1.3.1ServiceSideCoverRemovalandInstallationon
page54.
2. ProvidedtheInputVoltageiscorrect,withmainspoweron,usingamultimetersetforDCvoltage
measurements,placethemultimeterleadsintheHV+andHV-testpointsontheBackplane.Referto
Figure4-239BackplaneTestPointsonpage213forthisandthefollowingstep.Theresultshouldbe
220–280VDC.
3. Placethemultimeterleadsinthe+24and0VtestpointsontheBackplane.Theresultshouldbe22–26
VDC.
Page 204 of 294 - M-SV-001-EN Rev. H 1/23/2023