Futurehome Charge - Phase balancing

What is needed for phase balancing?

• Futurehome Charge
• Futurehome Smarthub
• Futurehome Energy meter (HAN, P1 or Tag)
• TN 3 phase electrical grid*

*As of now, we do not support phase balancing on IT/TT networks. 1 phase networks will benefit from dynamic load balancing, but there are no other phases to balance between.

What is phase balancing?

Phase balancing is a function that distributes the energy flow through the different phases to take advantage of the available capacity.

To easier understand this principle; Imagine the security control at an airport where 100 people are in line and you have one check point open. What phase balancing would do is to open the second check point, to get more people through.

If most of your household appliances get energy through “check point” one, Charge will use check point two or three to prevent overloading check point one.

The purpose of of this is that you can charge as fast as possible without tripping your main breaker or exceed the limit of your energy threshold.

The Futurehome energy meter will send information about the usage on each phase to the Smarthub, which then can use this info to charge through the phases with the most capacity.

Please note that this explanation is over simplified. For a more detailed explanation, please check the section at the bottom of the article.

How to activate?

Phase balancing is a feature under dynamic load balancing. When you activate dynamic load balancing, phase balancing will be activated if you have a 3-phase setup. You can find dynamic load balancing under Power Manager. Open app → energy tile → lightning in upper right → Dynamic load balancing. 

Advanced explanation

How phase balancing works depends on your electrical grid type, but 3-phase is required.

1. The Futurehome energy meter sends information about the phases to the Smarthub.

2. The Smarthub then calculates the available load on each phase.

3. The Smarthub runs the Phase balancing algorithm.

4. The Smarthub sends a command to Charge with information about how much load should be available on each phase.

Futurehome Charge requires a minimum of 6 amp to charge. This means, dependent on your grid type, that Charge will either pause charging or change to 1 phase charging if a phase at some point will have less than 6 amps available.

Dynamic load and phase balancing have a configurable safety margin of 5%, 10% (default) or 20%. In the illustration below, we use 10%. When the available load is 14 amps, Charge will use 12,6 amps (14 amps - 10%).

In our examples and explanations, we are using this as illustrations:

TN 3-phase:

On TN grid there are 3 phases (L1, L2 and L3) and a neutral. When you use 1 phase (regular household appliance), you are connected to one of the L’s and neutral. When you use 3 phases, you are connected to L1-N, L2-N and L3-N. This is more common on bigger construction appliances and EV chargers. On TN grids, you can not use 2 phases on a load. It’s either 3 phases or 1 phase.

In example 1, L2 is above the 6 amp threshold explained earlier and is therefore switching to the single phase with the most available capacity.

Example 1, switching from 3 phase to 1 phase.

The same principle works the other way around. In example 2, the load is made available on all 3 phases and the balancing will optimise back to 3 phase charging (Which in most practical cases will be faster than 1 phase charging.)

Example 2, switching from 1 phase to 3 phases.

IT/TT 3-phase:

On IT/TT grids there are 3 phases (L1, L2 and L3) without neutral. Where in TN you use one L and N, in IT and TT you use 2 L’s (L1-L2, L2-L3 or L1-L3). NOTE: IT/TT 3-phase is a very rare grip type, and Norway is the only country where this is widespread. That means that the vast majority of EVs are not made for 3-phase IT charging. Because of this, we have limited IT/TT charging to 1-phase.

In example 1, we can see single phase charging through L1-L3, where L3 is overloaded. This results in limiting the load to fit between the minimum charging current and the available capacity on that phase.

The reason the charging doesn't switch over to L1-L2 is because none of the AMSs in Norway transmit information about the load on phase 2. Therefore, we don't know how much capacity is available, which increases the risk of overload.

Example 1, adjusting the L1-L3 current to the available capacity.