Modeling of Single phase IBC with Active Power Decoupling

A battery charging scheme for Electric Vehicle using a single-phase integrated battery charger (IBC) is presented in this paper. In this topology, the driving motor and the driving inverter are re-utilized for charging purposes via a single-phase grid. The two windings of the motor are connected in parallel and work as interface inductance between the grid and the inverter. The two legs of the inverter work as a single-phase front-end converter while charging the battery. When the battery is charged using a single-phase supply, a second harmonic ripple power will be transferred from the grid to the battery along with the constant real power. Hence there will be a ripple voltage along with the DC voltage in the battery. To remove this ripple voltage, a decoupling circuit is developed using the third winding of the driving motor and the third leg of the driving inverter to bypass the ripple power from passing to the battery. But by using this method, mutual coupling is found to exist between the windings of the machine even though they are used for two different circuits. In this paper, a proper mathematical model of the single-phase IBC with active power decoupling is derived. The decoupling current is calculated by considering into account the mutual coupling between the three windings of the motor. Simulation results are attached to verify the derived results.