Control strategies for electric vehicle charging infrastructure

Abstract

The Electric Vehicles (EVs)/ plug-in hybrid EVs (PHEVs) are slowly and newlinesteadily making inroads, in public as well as personal vehicle markets worldwide. The newlinelimited fuel reserves and pollution caused due to conventional internal combustion newlineengine (ICE) driven vehicles are the main driving elements for allowing a paradigm shift newlinetowards EVs. However, with the rapidly increasing demand of EVs, many experts had a newlinemanifest concern regarding the charging infrastructure and thus, several studies have newlinebeen presented over it. With the growing popularity of EVs, power distribution networks newlineare under stress to accommodate the charging infrastructure. The large-scale penetration newlineof EV charging loads in low voltage network may lead to severe voltage fluctuations, newlineoverloading of distribution transformer and harmonics related power quality issues. newlineTo subsides the negative effect of EVs on distribution system, smart charging newlinetechnique must be required. During one of the two operating mode, EV charger transfers newlineactive power to grid as well as compensating reactive power and known as Vehicle to newlinegrid (V2G) mode. This mode requires a bidirectional EV charger which may operate in newlineall over the active-reactive (P-Q) power plane. newlineMoreover, single phase single stage EV chargers have inherent problem of newlineproducing second order ripple component on DC side. This problem is further newlineexaggerated during vehicle-to-grid (V2G) mode of operation where it may be normally newlinecontrolled to supply both active as well as reactive power. During the V2G reactive newlinepower compensation, the second order harmonics ripple component at DC side will newlineincrease which further reduces the life cycle and performance of battery pack. Therefore, newlinethe second order ripple component must be minimized for improving the life of battery newlinepack. newlineTherefore, the main aim of proposed study is to develop a robust control system newlinefor EV charger to operate it in wide range of G2V and V2G mode of operations while newlinemaintain the amount of ripple content on DC side within the permissible limit. The EV newlinecharger may supply active power to grid if required and compensate reactive power newline(inductive or capacitive) if a battery charges at slower rate. In that case, the remaining newlinerating of charger is utilized for compensating the reactive power for optimally utilization newlinecharger can work as an active power filter and improves the power quality. newlineviii newlineIn this regard, total four control techniques based on proportional integral (PI), newlineproportional resonant (PR), plant integrated proportional integrated (PIPI), repetitive newlinecontroller (RC), and adaptive neuro-fuzzy inference system (ANFIS) have been presented newlinein this thesis for two stage EV charger. The two control techniques have been presented newlinefor both ON board and OFF board EV charger. These EV chargers having two newlineconversion stages i.e., AC-DC and DC-DC converter. Both the converters have their newlineseparate controller. Moreover, for single phase single stage ON board EV charger, a newlinecontrol technique has been proposed for minimization of second order ripple presented newlineon DC side. For this, single phase AC-DC converter is utilized for charging purpose. newlineFurther, all the EV chargers are able to compensate the reactive power of local load. newlineThey all have active and reactive power input references where active command depends newlineon customer desire charging rate and reactive command is requested by grid. All EV newlinecharger prototype is controlled by using dSPACE 1104 in laboratory.