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Energies 2017,10, 616
poweroutput thantheothersource in independentmode. Lowswitchingfrequencyandhighpower
differencemethods coulddeterminewhichonewas themajorpower source andswitchover it at
anytimetoaccomplishpowerdistribution.Whenthe loadis low, themajorpowersourcecaneven
chargeanothersource. Table3 indicates therelationshipsbetween inverterbridgesâ switchingstatuses,
directionofphasecurrent i, andcurrentïŹow.GiventhatphasecurrentïŹowingfromleft to right is
positiveinFigure1,wecouldtell thatenergyïŹowbetweenthetwosourcescouldonlybeaccomplished
whenthe inverterbridgesâ switchingstatuseswereat twointermediatepotentials (00)and(11).
Table3.Relationshipbetweeninverterbridgeâs switchingstatesandpowerïŹowdirection.
Direction of
Phase Current
Inverter
Switching States 0i< 0i>
Boundary
potentials (01) Both power sources discharging Both power sources charging
(10) Both power sources charging Both power sources discharging
Intermediate
potentials (00) Power source 1 discharging
Power source 2 charging Power source 1 charging
Power source 2 discharging
(11) Power source 1 charging
Power source 2 discharging Power source 1 discharging
Power source 2 charging
Thetrigger regulationof inverterbridgesâ switchingstatuses in lowswitchingfrequencyandthe
highpowerdifferencemethodisdisplayedinTable4.
Table4.Dual inverter triggerrulesof twodifferentcurrentmodulationmethods.
Modulation
Pattern
Inverter
Switching States Low Switching Frequency Method High Power Difference Method
Boundary
potentials (01) Îi is in the area of Î â„i h Îi is in the area of Î â„i h
(10) Îi is in the area of Î â„i h Îi is in the area of Î â„i h
Intermediate
potentials (00) Îi crossed control line Î =i d and
switching state of inverter bridge on
major power sourceâs side is 0 Îi crossed control line Î =i d and
when power source 1 is major power
source: phrase current 0<i ;
when power source 2 is major power
source: phrase current 0>i
(11) Îi crossed control line Î =
âi d and
switching state of inverter bridge on
major power sourceâs side is 1 Îi crossed control line Î =
âi d and
when power source 1 is major power
source: phrase current 0>i ;
when power source 2 is major power
source: phrase current 0<i
These two improvedmethodsaddedtriggerconditionsof two intermediatepotentials,which
madetwopotentials, insteadofbeingtriggeredwhenÎi crossingcontrol linesÎi=±d, triggeredat
otherspeciïŹcconditions.Normallyonlyone intermediatepotentialwas triggeredinonehysteresis
period. The lowswitching frequencymethod, needed to conïŹrm the switching status of inverter
bridgeonmajorpowersourceâs side, remainsunchangedafter switchingwhenÎi crossingcontrol
linesÎi=±d. In thiscase, theswitchingstatusesofbothtwoinvertersâbridgeswouldnotbechanged
simultaneouslywhenÎicrosses thecontrol linesandtheswitchingfrequencyof inverterdevicescould
be lowered toaminimum. In thehighpowerdifferencemethod,whenÎi crosses thecontrol lines
Îi=±d,weneed todecidewhether to switchbasedon thepresentphase current iâs direction to
ensure themajorpowersourcecouldcharge theothersourcewhentheswitchingstatusof inverter
bridge isat twointermediatepotentials. Thismethodincreases thedifferencebetweentwosourcesâ
poweroutputsasmuchaspossible.
253
Emerging Technologies for Electric and Hybrid Vehicles
- Title
- Emerging Technologies for Electric and Hybrid Vehicles
- Editor
- MDPI
- Location
- Basel
- Date
- 2017
- Language
- English
- License
- CC BY-NC-ND 4.0
- ISBN
- 978-3-03897-191-7
- Size
- 17.0 x 24.4 cm
- Pages
- 376
- Keywords
- electric vehicle, plug-in hybrid electric vehicle (PHEV), energy sources, energy management strategy, energy-storage system, charging technologies, control algorithms, battery, operating scenario, wireless power transfer (WPT)
- Category
- Technik