EV charging sounds like it should be quite simple. Just plug the vehicle into the socket, come back a bit later and the vehicle is refilled and ready to go. With a single vehicle, and without too much concern for the electric bill, things can be that easy. But as vehicles and fleets grow, more complexities come into play. Larger vehicles usually use DC instead of AC charging, which leads to the question of what size charger. Once there are more EVs, how many EVs need to charge at the same time? Does every EV need a charger and if so, what size? Can multiple output chargers be used? Utilities charge large customers for peak power demand, which can make rare spikes from a few vehicles charging simultaneously very expensive. With the right charge management, the peak demand charges can often be cut dramatically. Simulating and modelling charging with ChargeSim can lower costs by selecting the right chargers and grid power.
Finding the Right Chargers
DC Chargers are used for fast charging passenger cars and for most heavy vehicles and available in different sizes. A vehicle which has a long or overnight break in the schedule may only need a small 30kW charger. When the schedule allows less time to charge more power will need to be delivered in less time. This requires bigger chargers, often 150kW or even 450kW for short layovers and on-route opportunity charging. Larger chargers are expensive, demand more power from the utility grid and fast charging is more detrimental to pack lifetime.
Vehicles in a fleet are often interchangeable, and in some cases instead of fast charging one vehicle, it can be swapped with another so they both have more time to charge.
As the fleet grows, there are more options to adjust the charging patterns to reduce the power and chargers required. ChargeSim helps analyze what size chargers are really needed, or if during peak periods fast charging is the only option.
Predicting Grid Needs
One of the first questions that comes up when planning fleet electrification is how much power will the depot need? Utilities have long lead times to deliver the high power connections needed for EV fleet depots, so the question often needs to be answered early in planning. The depot power required varies with fleet mileage, the time available for charging, the amount of overlap between charging sessions and the charge management strategies used. ChargeSim translates the planned schedule into utility requirements for the right size connection early in the planning process, preventing costly over or under installation.
Reducing Grid Needs
Charge Management is becoming essential for large EV charging installations to prevent expensive peak power demand charges. Without charge management rare cases where many vehicles are charging simultaneously at high power for just a few minutes can add €10k to a monthly electricity bill, sometimes locked in for a year. Charge Management and Smart Charging can dramatically reduce utility bills and make much better use of chargers, especially with multiple outputs. However, reducing utility capacity too much can also cause problems if the fleet is unable to recharge with enough energy. Reducing the installed electric power capacity at the start of the design phase saves installing unnecessary cables, transformers and chargers, reducing capital costs. ChargeSim finds the right balance between over-installation and high utility bills and inadequate power and empty vehicles early in the design.
Evaluating Smart Charging Methods
There are several basic methods for smart charging, and the choice can have a dramatic impact the base performance. For example, if, to keep under a site power limit, charge management limits the chargers to less power than they are request , how much power should each vehicle get? Two simple methods are based on average power and first-come, first-served. With average power charging, the available power is distributed evenly between all the vehicles . This results in lower power charging for each vehicle, and all the vehicles take longer to charge.
The alternative, First-Come, First-Served charging, provides the available power to the first vehicles that arrive, before charging subsequent vehicles in turn. This means the first vehicles are recharged and ready to dispatch again much sooner. Faster charging though can be less efficient and isn’t always preferred.
Both have advantages and disadvantages, depending on the fleet and schedule. ChargeSim helps find the right smart charging methods for a fleet, base and schedule.
Minimize Excess Capacity
Initial EV charging installations were trials with just a few vehicles, but now that full bases are being electrified, charger and electric grid sizing are becoming more important. Oversizing charging infrastructure wasn’t a major concern in initial trial installations, since the first priority was making sure the trial went well. Future growth would use up any extra capacity already installed. EVs are maturing, and fleet bases are becoming fully electrified. The numbers of vehicles are much larger, so the charger and electric power needs are much higher. With a fully electrified base there is no future need for extra chargers, without more parking space, vehicles and service needs. Some reserve capacity should be planned in, and extra capacity to take advantage of smart charging and flexible energy tariffs can be valuable. Unnecessary excess charging capacity is no longer an investment in the future, it is just waste. ChargeSim helps avoid wasted charging capacity and excess installation costs.
Take Full Advantage of New Charger Technology
Multiple output chargers are starting to play an increasing role in EV charging. A single charger which can charge one or more vehicles in sequence or simultaneously at lower power can make much better use of the expensive charger and electric grid capacity. Multiple output chargers move the charging to different vehicles, instead of labor intensively moving the vehicles to the charger one at a time. Which parking positions are connected to which charger outputs can have a dramatic impact on the overall performance. A charger connected to an empty parking space or to a full vehicle adds no value, but with multiple outputs it needs to be the right mix. Multiple output chargers should be designed with the parking arrangement in mind to make maximum use of the chargers and provide enough flexibility. ChargeSim helps design multiple output chargers to maximize performance.
Step up from Trial and Error to Design
Simulating a design, predicting performance and being able to iterate virtually early on in the design process helps avoid excess costs in over-installation and change orders later on. EV charging is placing bigger demand on capital budgets and electric utilities and is demanding the same methodical design approaches applied in other areas. ChargeSim engineers and designs charging infrastructure configurations up front, eliminating high stakes trial and error.