On the Electric Energy Rate Plans in Charging Electric Vehicles

To charge the electric energy for electric vehicles (EVs), various charging rate plans have been developed based on AC slow charging and DC fast charging. Flat rate plans are available for both AC and DC charging, where the EV charging fee typically depends on the amount of electric energy used for charging. For AC charging, a dynamic rate plan of time-of-use (TOU) is provided in addition to the flat rate plan. For DC charging, there are also subscription or membership rate plans that are driven by promotions for purposes such as car sales or encouraging the use of specific charging stations. In this paper, by formulating charging equations in terms of the charging fees, we first summarize and compare the various charging rate plans currently being commercialized. Furthermore, assuming a combined usage scenario of both AC and DC charging, combined charging plans of the flat and TOU rates for AC charging, and the flat and subscription rates for DC charging are analyzed. Through simulations based on charging fee formulations for the combined charging scenario, the analyses are conducted and appropriate charging plans for specific driving distances and DC charging portions depending on the EV drivers are suggested. The formulations in this paper can be extended to accommodate various charging rates and base fees, providing specific guidelines selecting for appropriate charging types.