Dynamic power management

Dynamic power management changes charging limits according to spare capacity in the electrical installation. When other demand rises, charging is reduced. When capacity becomes available, vehicles can use it again.

Total demand is different from a charging budget

At a metered control point, EMS receives the total consumption of appliances and chargers. At a point without a meter, it receives a budget reserved for charging only. If a building consumes 80 kW without vehicles and the total limit is 100 kW, approximately 20 kW remains for vehicles. If the BMS sends a 20 kW EV budget directly, EMS does not subtract the same building demand from it again.

Amperes, kilowatts and phases

An A limit is checked on each physical phase. A kW limit checks total active power. A single-phase vehicle does not necessarily use L1 at the main meter: connector wiring and phase rotation also matter. EMS accounts for this mapping; it does not physically switch phases.

At 230 V and a power factor of 1, a single-phase vehicle drawing 16 A uses about 3.7 kW, while a three-phase vehicle drawing 16 A uses about 11 kW. Equal amperes therefore do not mean equal power. This is an indicative calculation, not a fixed voltage for every site.

Every point constrains its downstream chargers

The main supply, a distribution board and a dedicated charging cable can each have a limit. The allocation must satisfy all of them at once. Metered points account for other loads too. On an EV-only circuit, capacity is allocated against permitted charging limits so vehicles can actually use the power assigned to them.

Meters may be summed only when they cover the intended total without overlap. A main meter already including a subcircuit must not be added to that subcircuit meter. Independent supplies retain their own current limits.

Response is evaluated over time

EMS uses a short measurement history and the expected effect of commands already sent. It does not repeatedly send the same limit merely because the next vehicle reading has not arrived. Reducing a limit from 20 A to 18 A, however, does not reduce consumption by a vehicle already drawing only 16 A.

Command acceptance is different from measuring its physical effect. End-to-end response depends on metering, connectivity, the station and the vehicle. A power limit provides ongoing regulation; it is not a separate optimiser for 15-minute demand peaks. Electrical protection remains essential.

When there is not enough capacity for everyone

AC charging uses zero or whole amperes from a functional minimum of 6 A. If the minima do not fit, some vehicles wait. Priorities, energy and rotationgovern the allocation. Compatible DC stations are controlled in power and also respect the shared rating of a station with multiple outputs.

Where to go next

Cloud EMS technical guide · Product guide (PDF, Slovak) · Technical guide (PDF, Slovak).