1 : n AC/DC Converter DC/DC Converter Battery La Lb Lc Vbat v1a v1b iL1 Ta1 Ta2 Ta3 Ta4 Ta5 Ta6 Tb1 Tb2 Tb3 Tb4 Tb5 Tb6 R1 L1 R2 L2 R3 L3 AC Grid T1 T2 T3 T4 T5 T6 VAC/DC IAC/DC Iba t Fig. 1. Proposed bidirectional charger Adaptive Control Of A Three-Phase Dual Active Bridge Based For Electric Vehicles Charging Rawad Zgheib Electrical Engineering Department ÉTS(École de Technologie Supérieure) Montreal, Canada rawad.zougheib@gmail.com Kamal Al-Haddad Electrical Engineering Department ÉTS(École de Technologie Supérieure) Montreal, Canada kamal.al-haddad@etsmtl.ca Innocent Kamwa IREQ (Hydro-Quebec’s Research Institute) Varennes, Canada kamwa.innocent@ireq.ca Abstract— This paper proposes a control algorithm that controls a DC/DC converter within a capacitorless battery charger for Electric Vehicles (EVs). The charger is composed of an AC/DC converter connected to a three-phase DAB (Dual Active Bridge) DC/DC converter with no capacitor between those two. The proposed control adds an additional degree of liberty in order to deliver the reference charging or discharging power while mitigating the DC/DC converter’s drawbacks, dealing with a varying voltage since there is no capacitor, operating in a wide range power spectrum, and controlling the transitional instants. The control algorithm’s performance is verified using Matlab/Simulink, and the results are discussed. Keywords—smart grid, dual active bridge, isolated DC/DC converter, fast charging, electric vehicles I. INTRODUCTION Connecting EVs to the smart grids offers several advantages presented in the literature [1], such as improving grid stability, regulating the voltage and the frequency [2], acting as energy storages for renewable energy sources [3], smoothing out the demand curve by injecting power in the grid, and improving the power quality by acting as power filters [4]. The circulating power between the EV batteries and the grid ranges from low power (3 kW for slow charging according to the SAE charging standard [5]), to very high charging power that reduces considerably the charging time and can reach 150 kW (according to the CHAdeMO charging standard [6]). Note that several projects aim to further increase the charging power in order to achieve an ultra-fast charging for the EV batteries, which constitutes an important step in pushing the EVs to become a serious competitor of the conventional vehicles. In addition, reverse power (from the battery to the grid) has a more restricted power range. Several converters were studied and used in vehicular chargers. The DC/DC converter in the charger topology is preferred to be isolated, since it respects the charging standards more easily and increases safety [7]. The conventional DAB topology is chosen in this paper over its variants (resonant DAB [8-10] and multilevel DAB [11, 12]) since the resonant DAB adds more passive components which increases the size of the charger and the multilevel DAB has more switches which increases the control complexity [17] and reduces the overall efficiency [13]. The choice of the three-phase DAB [10,16] over its single- phase version [14, 15] is due to the fact that the switches’ current and voltage stress are lower than in the single-phase DAB [15], as well as the possibility to provide a higher maximum circulating power in order to allow fast charging. The DC/DC converter chosen is also naturally bidirectional, thus allowing battery charge and G2V (Grid-to-Vehicle) operation when necessary. The three-phase DAB used in battery storage applications is mentioned in several papers, such as [16-18]. The common point between these references is the fixed duty cycle of the two bridges, which makes the control much simpler, but results in the deterioration of the efficiency when the ratio between the input and the output voltages is different from 1 and when the power changes on a wide range. In addition to that, closed-form modulation is the only type of control used for this topology, which gives satisfying results in the steady state operation but is unable to control the transitional states when the reference power or the voltage change. Therefore, this paper proposes a three-phase DAB with its discussed drawbacks in the first section. The complete control is detailed in the following section; this control combines the closed-form modulation and the traditional PI controller for better results, which are shown, discussed and compared to the traditional modulation. II. DC/DC CONVERTER STRUCTURE The three-phase DAB shown in Fig. 1 is composed of two three-phase full bridges connected by a high-frequency isolation transformer. Since this converter is connected to the output of the AC/DC converter with no capacitor in between, the AC/DC side voltage ( / AC DC V ) has an important ripple and its average value varies (depending on the charging protocol used [19]). The removal of the capacitor reduces the size of the  l -))) 