# An EV SRM Drive and Its Interconnected Operations Integrated into Grid, Microgrid, and Vehicle
## 1 Introduction
For an EV drive with regenerative braking capability, bidirectional converters [18] must be adopted. On the other hand, interleaved converters can be employed to have fault tolerance and lower current ripples [24]. In the developed EV SRM drive, the interleaved boost/buck converter is adopted as the battery followed interface converter. For an EV, it is necessary to make the grid-to-vehicle (G2V) charging operation [25; 26; 27; 28; 29; 30] through the onboard charger when the EV is in idle mode. The charger can be formed using integrated schematics [25; 30], or can be added externally. Generally, battery charging can be classified between level 1 and level 3 [31; 32; 33]. The related standards can be found in [32; 33]. Limited by size and weight, the EV onboard charger usually performs level 1 and level 2 charging levels. In order to conduct G2V operation, the EV charger usually includes an AC/DC switch mode rectifier (SMR) to possess the power factor correction (PFC) function, and a DC/DC converter is equipped to control the charging voltage and current. The survey for some existing SMRs is referred to in [34; 35; 36]. And some control researches for SMRs are presented in [37; 38; 39]. Furthermore, galvanic isolation is required for safety reasons. Despite a low frequency transformer for galvanic isolation being very simple to use, it is too bulky and heavy to equip on the vehicle. To solve this problem, one can employ the dual active bridge (DAB) converter using a high-frequency (HF) transformer [40; 41]. Moreover, the CLLC resonant converters [42; 43] can be applied to have higher efficiencies. EVs can reduce carbon emissions in transportation. However, charging during peak hours will increase grid demand, which may produce additional carbon emissions in the electricity sector. Therefore, adopting EV grid-connected operations can reduce the carbon emissions of power generation. With bidirectional onboard chargers, EVs can conduct the vehicle-to-grid (V2G) operation [44; 45; 46]. When the grid demand is high, EVs can provide battery power to support the grid, which can utilize the energy effectively. However, the impacts on the grid must be considered [47; 48; 49]. With the equipped schematic for V2G, EVto-home (V2H) [50] and EV-to-building (V2B) [51] can also be made. For the V2B operation, the energy management optimization controls considering uncertain PV energies can be found in [51]. There also exist some possible interconnected operations regarding EVs. Vehicle-to-vehicle (V2V) [52; 53; 54] is one example application. It may be applied in roadside assistance for EVs. In [55; 56; 57], the V2V operations using the onboard charger schematic and motor windings are presented. When an EV has exhausted its battery-stored energy, it can be charged from another EV. The other possible interconnection is EV to microgrid, performing microgrid-to-vehicle (M2V) and vehicle-to-microgrid (V2M) operations [58; 59; 60]. The EV battery can be charged from the microgrid. Effectively utilizing the renewable energies to charge the EV battery can reduce the charging power needed from the grid and consumed fossil energy [61; 62; 63]. Conversely, as the energy deficiency in the microgrid occurs, the EV battery can provide energy support to the microgrid. The interconnection between the microgrid and EVs can express their complementarities. Regarding the popularization of G2V charging and V2G discharging operations between EVs and the utility grid, many reliability, safety, functionality, interference, and harmonic impacts to the grid are explored in [64; 65; 66].