New energy exchange systems between EVs and the power grid are made possible by the evolution of electric vehicle technology. Two such developments are the bidirectional power flow made possible by Vehicle-to-Grid (V2G) and Grid-to-Vehicle (G2V) systems. EVs may replenish stored energy for the grid in V2G mode; in G2V mode, they utilize grid power to charge their batteries. This capacity helps with load balancing, voltage control, and general system dependability, therefore supporting grid stability. This work proposes a dual-mode onboard battery charger suitable for V2G and G2V operations. The suggested approach connects EV to the grid via bidirectional converters—more specifically, a bidirectional AC–DC/DC–DC converter. Third-Order Sinusoidal Signal Integrator (TOSSI) control approach manages the bidirectional AC-to-DC converter, therefore guaranteeing good steady-state and dynamic performance. Furthermore, under control while charging and discharging are the voltage and current of the battery via a PWM-based controller. Additionally examined in this work is how fluctuations in nonlinear load impact system behavior. Extensive simulations run in the MATLAB/Simulink environment confirm the proposed method.