The linear INCH power management algorithm will always try to find the optimal charging current for an individual vehicle that is currently charging in a cluster while trying to maximally utilize all the available phases during charging.

The cluster will always assume that a vehicle began charging with an empty battery. If the battery capacity of the vehicle has not been defined, the cluster will assume that the battery capacity is 100 kWh.

The algorithm will divide the available charging current of the cluster between the vehicles which are currently charging based on the number of phases they can charge on, as well as their departure times. As the algorithm will always try to maximally utilize all the available phases, vehicles being able to charge on two phases will always have a charging priority over single-phase vehicles, while three-phase vehicles will always have a charging priority over single- or two-phase vehicles.

The following graphs (Figure 1, Figure 2) will further explain how prioritizing three-phase vehicles over single-phase vehicles maximizes the power used for charging in the cluster.

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Figure 1

As we can see on the Figure 1, the green vehicle (three-phase) is in our case able to charge with 30 A on all three phases.

Figure 2 demonstrates what happens when a single-phase vehicle connects to the cluster (in addition to the green vehicle). As we can see, the single-phase (orange) vehicle can only charge on one of the three phases. However, since electric vehicles can only charge with the same electric current on all phases on which they are charging, the reduced available current for a three-phase vehicle on one of the phases to e.g. 6 A (Figure 2) will result in the fact that the vehicle will only be able to charge with 6 A on all three phases. Therefore, some electrical current on phases 2 and 3 will stay unused.

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Figure 2

In addition to the number of phases a vehicle is able to charge on, the cluster power management algorithm takes into account the departure times of the vehicles in order to determine the charging priorities. The closer the vehicle's departure time, the higher the charging current the vehicle will be allowed to charge with. If a time of departure is not determined by the user of the vehicle, the power management algorithm will predict a departure time in 6 hours from the beginning of the charging session by default.

After the departure time of a vehicle has been reached, the vehicle will continue to charge if not full. In fact, the charger will avoid at all costs stopping the charging of any of the vehicles, until fully charged.

E.g., if there are 5 vehicles charging in a cluster, and the cluster has 32A of current available, the algorithm will divide this current between all vehicles in a way that none of the vehicles would stop charging. In our case, all the vehicles would therefore only be able to charge with 6A, as for the vehicle to be able to charge, at least 6A of electric current are required. If the current available to the cluster is too low for each of the vehicles to receive at least 6A of current, then the charging of as many vehicles as necessary will be stopped, until the rest of the vehicles can receive at least 6A of electric current.

It is not always possible to predict which vehicle will stop charging first, as the algorithm in this case does not take into account the departure times of the vehicles. Instead, one of the vehicles that have the least contribution to the optimization of the total energy flow in the cluster will be disconnected first. This means that single-phase vehicles will be disconnected before two-phase vehicles, and two-phase vehicles will be disconnected before three-phase vehicles. However, the selection of the vehicle that will be disconnected among the vehicles with the same number of phases (e.g. among single-phase vehicles) is random.

The following examples will help to better understand the behaviour of cluster power management in different situations.

Scenario 1 : A single-phase vehicle and a three-phase vehicle with different departure times and enough time to full charge

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Figure 3

Let's say a green vehicle (3-phase) connects to the charging cluster and begins to charge. The more power the vehicle can charge with, the shorter the total charging time of the vehicle will be. In our case, the vehicle may charge with up to 32 A per phase, as this is the limit of the charger (Figure 3). We assume that the battery capacity of the green type of the vehicle has not been defined in the system, which means the cluster will assume that the battery capacity of the green vehicle is 100 kWh, and that the battery is empty. Therefore, the cluster will predict 100 kWh for charging the green vehicle and will start charging immediately.

An orange vehicle then arrives and connects to the cluster (Figure 4). The battery capacity of the orange vehicle is 100 kWh and the vehicle can only charge on a single phase with a current of up to 32 A. The departure time of the orange vehicle is sooner than the departure time of the green vehicle, which means that the charging priority of the orange vehicle is greater than that one of the green vehicle.

Consequently, the orange vehicle will be allowed to charge with all available current (up to 32 A) before the green vehicle. However, as the charging cluster will always try to maximize the power consumption of the cluster (will try to use as much power for charging of the vehicles connected to the cluster as possible), the orange vehicle will only be allowed to charge with up to 32 A until the green vehicle must begin to charge in order to fully charge by its departure time. After the green vehicle will have begun charging, the orange vehicle will only be allowed to charge with 6 A until its departure time, regardless of the battery charge.

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Figure 4

Scenario 2: Two three-phase vehicles with different departure times (priority charging)

A three-phase green vehicle is charging at the charging cluster, same as in the beginning of Scenario 1 (see Scenario 1 and Figure 3).

A red vehicle then arrives and connects to the cluster (Figure 5). The battery capacity of the red vehicle is 100 kWh and the vehicle is able to charge on all three phases with a current of up to 32 A per phase. The departure time of the red vehicle is sooner than the departure time of the green vehicle, which means that the charging priority of the red vehicle is greater than that one of the green vehicle. Consequently, the red vehicle will be allowed to charge with all available current (up to 32 A per phase) sooner than the green vehicle (in the mean time the green vehicle would be allowed to charge with 6 A only).

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Figure 5

However, as both vehicles can charge on all three phases simultaneously, departure times of both vehicles are approaching but the red vehicle has been receiving the power faster than the green vehicle, both vehicles will eventually reach an equal charging priority, which means that the charging current between them will split equally until either of the vehicles is fully charged or disconnected from the charger.

Scenario 3: A single-phase vehicle and a three-phase vehicle with different departure times, not planning for full charge

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Figure 6

A green vehicle (three-phase) is charging on one of the chargers in the charging cluster. The cluster assumes that the vehicle has a battery capacity of 100 kWh and that the battery is empty. The vehicle can charge with 32 A per phase (3 x 32 A) for the entire duration of the charging session. Time until the set departure of the vehicle is shorter than the time in which the vehicle would be able to fully charge in case its battery is truly empty (Figure 6). If owner of the green vehicle does not unplug the vehicle from the charger, the vehicle will keep charging until unplugged or until fully charged.

An orange vehicle (single-phase) connects to another charger in the cluster. Just like with the green vehicle, the cluster assumes by default that the orange vehicle has a battery capacity of 100 kWh and that the battery is empty. The departure time of the orange vehicle is later than the departure time of the green vehicle, however here too, the time until departure of the orange vehicle is shorter than the time in which the vehicle would be able to fully charge in case its battery is truly empty.

As the green vehicle is able to charge on all three phases simultaneously, the cluster will give it a charging priority (same as in Scenario 1). This means that until the battery of the green vehicle is full or disconnected, the orange vehicle will only be receiving 6 A of electric current. After that, the orange vehicle will be allowed to charge with max. available current (up to 32 A).