To　reduce　impacts　of　the　high　rate　current　charge　and　discharge　induced　by　frequent　acceleration　and　deceleration　of　the　vehicles　to　the　battery　in　view　of　pure　electric　vehicles　(EV),　a　hardware　configuration,　control　algorithm　design　and　an　experiment　study　on　battery+supercapacitor　hybrid　energy　storage　systems　are　addressed.　At　first,　a　topology　structure　with　respect　of　the　hybrid　energy　storage　systems　is　introduced.　Then,　a　key　component　of　DC/DC　converter　is　modeled,　and　its　efficiency　behavior　is　evaluation　through　experiment.　A　primary　hard-ware　configuration　of　the　hybrid　energy　storage　systems　is　completed,　and　a　power　splitting　ratio　(PSR)　control　algorithm　is　proposed.　Hard-ware　in　loop　experiments　confirm　that　the　supercapacitor　has　a　function　to　smooth　the　power　supplied　by　the　battery　and　therefore　the　life　time　of　the　battery　can　be　prolonged　and　improves　EV＇s　performance.　©　2012　Chinese　Assoc　of　Automati.