Harmonic Analysis for Bidirectional Grid-Connected Converter for Electrical Vehicle During Charging and Discharging Operations

The fossil fuel-powered transportation is known to emit pollution and has been an active contributor to the problem of greenhouse gas. The fossil fuel imposes a huge burden on the economy of a country as non-renewable energy resources are limited. The solutions are being designed to implement the use of renewable energy resources in the transportation sector by introducing battery-powered electric vehicles. The battery charging utilizes three major levels of charging; level 1 resembles slow charging with power output 1.4–1.9 kW, level 2 stands for primary charging with power output 4–19.2 kW, and level 3 is fast charging with power output 50–100 kW. The charging stations are mostly unidirectional, and efforts have been made to develop bidirectional chargers. The energy storage capability of the EV batteries would help the grid to see the EV batteries as a flexible energy resource which can be charged during off-peak hours of the grid and discharged during peak hours of the grid, thereby supporting the power grid to maintain demand-supply balance and reduce the need of additional peak-hour generators. A bidirectional power converter is implemented in the paper to connect the power grid to the electric vehicle battery and facilitate energy transfer between the power grid and the battery of electric vehicle. An impact of such a connection with respect to harmonic generation in the power grid is studied, and in both the modes of operation, the THD is found to be within limits as specified by the prevailing standards.