Electric Vehicles (EVs) are growing in popularity. After 2035 ICE Vehicles will be hard to find. The increased consumption to charge EVs will mean that the grid and the electrical infrastructure in buildings will require major investments and refurbishments; hence the need for an EV charging control system to regulate how much power is allocated to each electric vehicle. Let's look at the different modes of Energy Management.

Time Allocation

Time allocation follows simplified scheduling; this type of EV charging controller divides electrical power among electrical vehicles based on how long they have been in the queue for a charge. The best way to think about this type of controller is like the timer for our garden lights, or the timer for an irrigation system, that turns on and turns off at set times, regardless of whether there is an EV connected or not.  This makes time allocation ideal for charging parked fleets where the similarity of vehicles, battery size, and charging time can be predetermined to satisfy the charging requirements of specific sets of vehicles. When EV's are of a different make, size, and do not have a pre-determined route it may be a bigger challenge for a "Time Allocation" EV Energy Management System EVEMS to satisfy the need for charging.

Power Allocation

This type of EV Energy Management System divides electrical power available among electrical vehicles proportionally. The best way to think about this type of controller is as a water bucket, that is full and its contents will be distributed amongst several cups. If there is only one cup, that cup takes all the water, however, if there are ten cups each cup takes a tenth of the bucket content.  Similarly, the kW capacity available is split or distributed amongst the chargers providing charge to the EVs. Under this model there are two modes of operation;

• The Non-Monitored type, looks at the number of EVs in need of charge and distributes the energy proportionally, and
• The monitored type; looks at the actual consumption and distributes the charge based on the summation of all the individual consumption. 

Benefits of Power Allocation Systems

The main benefit of a Power Allocation EVEMS is that it can dynamically manage electrical supply and demand. Let’s say that the electrical grid only has enough electrical energy to support 100 units of electrical power (and each unit of electrical power equals one kW). If all the electric vehicles begin charging at once, then there will not be enough electricity for all cars because most EVs draw more than one kW as they charge. This would cause an overload on the electrical grid, trip the feeder breaker, and shut down the power for all the electric vehicles.  

A Monitored Type of Power Allocation EVEMS would determine how much electrical energy each electric vehicle needs before allowing it to begin charging. In contrast with time allocation type charging, power allocation enables the charging of diverse electric vehicles, whether fully electric or hybrid, of different brands, of different battery sizes, and with different levels of battery capacity at the start of the charging period to be charged, and allowing each to charge at the highest rate available for the time on charging mode. This way, electric vehicles can charge to their maximum potential while also ensuring that there is enough electrical energy for everyone at a given time during the sharing period. This feature makes the Monitored type of EVEMS the most flexible and efficient way to manage the limited energy available for charging.

This way, smaller EVs that need less electrical energy, or EV's with higher battery capacity, that just need to top-up can charge faster; which means electrical energy can be made available to others while still connected to the charger network. This is how electrical grids and the electrical infrastructure in buildings can support more electric vehicles than they would otherwise because power allocation controllers make the most out of limited electrical supply.  

Metering is also a critical component in monitoring consumption and allocation; particularly in Multi-Residential buildings, strata, and condos, where the Home Owners Associations need to recover energy costs in addition to a flexible and efficient energy management system. 

Selecting the right EV EMS can save time and costly refurbishments at the main service switchboard, and satisfy EV charging needs for the average EV owner.