### Literature Review
As a result, it reduces the fuel consumption of vehicles by between 4.5 and 13.3%. These results were deduced under the worldwide harmonized light vehicles test cycle (WLTC) and new European driving cycle (NEDC). These results can also be tested under different control strategies and various driving cycles. It validates and verifies the best fuel economy given by an FLC as compared to a traditional controller. Some researchers gave preferences in the use of permanent magnet synchronous motor (PMSM) in HEVs. Power distribution in these strategies is carried out by using a fuzzy logic-based power management strategy without the need for an extra controller. A back-stepping direct torque control technique (BS-DTC) [33] with the help of space vector modulation (SVM) was used. By using this technique, the torque and flux of the PMSM machine has been controlled. The regenerative braking mode of charging the SC was used to restore the power and voltage regulation. It also justifies the robustness and stability of power management strategy and removes the effect of chattering. However, the choice of the converter and its losses were ignored. The main component used and requirements for the fabrication of HEV are discussed. Types of motor, converter, control strategies, and energy storage devices were also discussed in detail. The low power and limited range of HEVs can be overcome by using a combination of different energy storage devices. Among them, battery packs with ultra-capacitors, fuel cell batteries, and ultra-capacitors, etc. can be used [34]. [PERSON] et al. [35] discussed different topologies and arrangements of batteries. SC, with their pros and cons used for HEVs, are also discussed. The parallel combination of battery and SC always requires two converters capable of supplying constant voltage. These converters also limit the current and voltage charging the battery. Series combinations of ESSs require the balancing of power flow and minimize the converter losses. The overall system efficiency can greatly increase by using a UPTA system. This UPTA system can be combined with another control strategy to control the battery charge or discharge rate. Following the research literature provided, the research work in [16; 17] has few limitations. One of the major drawbacks is the decrease in battery life. The life of the battery is very much expected to decrease while braking and accelerating the EV. Batteries face huge stress during continuous charging and discharging. In [27], a detailed review of HEVs based on fuel cell/battery/SC has been presented; however, it has one drawback: that the overall system of EV becomes expensive due to the implementation of three different ESSs. Moreover, there is no method provided to minimize the current spikes on the battery side during braking and acceleration. To overcome these drawbacks and similar issues in the literature, an FLC-based EMS has been presented in this research for HEVs. To eliminate the cost constraint of the battery, SC was used as the secondary energy storage device which was being used to charge the battery regularly. A UPTA technique along with FLC was implemented to efficiently manage the power flow. In order to reduce the inrush current on the battery side during braking and acceleration, a SEPIC converter was designed. The feature of the SPEIC converter is to provide a constant current to the battery so that battery health and the life cycle can be improved.