Research on sustainable hybrid drive

Hybrid dri­ves, in which elec­tric motors and inter­nal com­bus­tion engines work togeth­er, enable rapid CO2 sav­ings in road traf­fic — pro­vid­ed the dri­ve sys­tem of such a vehi­cle is designed from the out­set to oper­ate as effi­cient­ly as pos­si­ble. In FVV’s new hybrid research pro­gram, engi­neers are work­ing across com­pa­ny bound­aries to devel­op the meth­ods and tech­nolo­gies need­ed to achieve this.

Ini­ti­at­ed by the FVV Board of Direc­tors in 2020, the hybrid research pro­gram has now led to con­crete projects deal­ing with the sus­tain­able design of hybrid dri­ves. The researchers are focus­ing less on con­crete indi­vid­ual tech­nolo­gies and more on their inter­ac­tion. The Tech­ni­cal Uni­ver­si­ty of Darm­stadt, for exam­ple, is inves­ti­gat­ing how the the­o­ret­i­cal­ly infi­nite com­bi­na­tions of bat­ter­ies, elec­tric machines, motors, trans­mis­sion vari­ants and soft­ware-based oper­at­ing strate­gies can be con­vert­ed into a mod­u­lar sys­tem. Such an approach is intend­ed to max­i­mize envi­ron­men­tal ben­e­fits on the one hand, while keep­ing pro­duc­tion costs low by reduc­ing the num­ber of vari­ants on the oth­er, thus serv­ing to achieve a high lev­el of mar­ket acceptance.

One of the researchers’ goals is to devel­op a soft­ware pro­gram that cal­cu­lates mod­u­lar archi­tec­tures of the hybrid pow­er­train once the bound­ary con­di­tions have been entered and takes the prop­er­ties of the com­po­nents into account. In doing so, the sci­en­tists are fol­low­ing an object-ori­ent­ed approach from com­put­er sci­ence, which should sig­nif­i­cant­ly reduce the com­put­ing time. The pro­gram will be shared with all com­pa­nies col­lab­o­rat­ing in the FVV once the project is com­plet­ed. “Medi­um-sized sup­pli­ers in par­tic­u­lar can ben­e­fit sig­nif­i­cant­ly from this,” says Mar­tin Nitsche, deputy man­ag­ing direc­tor of the research association.

Highly flexible drive

The goal of any hybrid devel­op­ment is ener­gy-effi­cient oper­a­tion. At the same time, how­ev­er, exhaust emis­sions must be min­i­mized and a high lev­el of dri­ving com­fort must be made pos­si­ble. But in which spe­cif­ic sit­u­a­tions do con­flict­ing goals arise? And what does the high flex­i­bil­i­ty expect­ed of the com­bus­tion engine mean for its tech­nol­o­gy? Researchers at RWTH Aachen Uni­ver­si­ty are try­ing to answer these ques­tions in anoth­er project.

To do so, they are link­ing var­i­ous sim­u­la­tion meth­ods that can be used, for exam­ple, to include exhaust gas aftertreat­ment or ther­mal man­age­ment. With ‘pre­dic­tive trav­el man­age­ment’, it should be pos­si­ble to take spe­cial emis­sion zones and unfore­seen events such as traf­fic jams into account. The research project will cul­mi­nate in the devel­op­ment of a man­u­fac­tur­er-neu­tral, holis­tic devel­op­ment method­ol­o­gy for hybrid dri­ves that will sim­pli­fy work on effi­cien­cy tech­nolo­gies for small and medi­um-sized com­pa­nies as well.

CO2-neutral hybrid drives

Hybrid dri­ves are only free of cli­mate-dam­ag­ing emis­sions if the elec­tric motor is pow­ered exclu­sive­ly by green elec­tric­i­ty and the com­bus­tion engine by syn­thet­ic fuels such as green methanol. The FVV project ‘ICE2025+’, which was com­plet­ed in 2020, had already shown that an effi­cien­cy of more than 40 per­cent can be achieved with methanol oper­a­tion in almost all oper­at­ing ranges of the com­bus­tion engine.

At the best point, the engine opti­mized for hybrid oper­a­tion even achieved more than 46 per­cent with the syn­thet­ic fuel. In the fol­low-up project ‘ICE2030’, which has now been launched, a ther­mal effi­cien­cy of at least 50 per­cent is to be achieved (3). To this end, the par­tic­i­pat­ing sci­en­tists from the uni­ver­si­ties of Aachen, Braun­schweig, Darm­stadt and Stuttgart are inves­ti­gat­ing whether admix­ing hydro­gen will enable extreme­ly lean com­bus­tion with high sta­bil­i­ty. They also want to inves­ti­gate how the high excess oxy­gen affects the exhaust gas composition.

Oth­er ongo­ing or planned research projects relat­ing to hybrid dri­ves and their oper­at­ing strate­gies are con­cerned with the chal­lenges that arise when the inter­nal com­bus­tion engine has to step in only very rarely, but then very reli­ably. The phe­nom­e­na under inves­ti­ga­tion include ther­mal man­age­ment as well as, for exam­ple, acoustic per­cep­tion in the pas­sen­ger com­part­ment. Mar­tin Nitsche explains the rel­e­vance of this research as fol­lows: “Many tech­ni­cal ques­tions that have actu­al­ly been solved, such as cor­ro­sion and oper­a­tional sta­bil­i­ty, are posed in a com­plete­ly new way in hybrid drives.”

As part of the hybrid research pro­gram, the FVV is also test­ing a new award pro­ce­dure. In the call-for-ten­der process, a group of experts defines only the goal at the out­set. Research cen­ters can define the method­olog­i­cal path them­selves and pro­pose cor­re­spond­ing projects. Accord­ing to Nitsche, the new pro­ce­dure has already proven its worth: “It allows us to make even bet­ter use of the spe­cif­ic know-how at the research cen­ters for pre­c­om­pet­i­tive col­lab­o­ra­tive research.”