Managing electric current allocation between charging equipment for charging electric vehicles
A first and second charging equipment for charging electric vehicles share a current capacity. A controller coupled with the first and second charging equipment limits a total amount of current drawn through the first charging equipment and the second charging equipment to not exceed the current capacity. The controller communicates a first and second current limit to the first and second charging equipment respectively to cause a first and second electric vehicle to limit their current draw to not exceed the first and second current limit respectively. A sum of current to be drawn at the first and second current limit does not exceed the current capacity.
1. A method comprising:
receiving a first message that indicates a request for an allocation of electric current through a first charging equipment, wherein the first charging equipment shares a current capacity with a second charging equipment, and wherein at a time of receipt of the first message the second charging equipment is presently allocated electric current;
determining that granting the request would exceed the current capacity and
responsive to that determination, adjusting the electric current allocated to the second charging equipment such that the first charging equipment can be allocated electric current and the and the current capacity is not exceeded;
granting the request and allocating electric current to the first charging equipment.
2. The method of claim 1 , wherein the first message includes a requested amount of electric current, and wherein allocating electric current to the first charging equipment includes allocating the requested amount of electric current.
3. The method of claim 1 , further comprising:
wherein adjusting the electric current allocated to the second charging equipment includes transmitting a second message to the second charging equipment that indicates a first amount of current that is allowed to be drawn through the second charging equipment, wherein the first amount of current is a reduction from a most previous allocation of current for the second charging equipment;
prior to granting the request and allocating electric current to the first charging equipment, receiving an acknowledgement message that indicates that the second charging equipment is limiting current draw in accordance with the second message; and
wherein allocating electric current to the first charging equipment includes transmitting a third message to the first charging equipment that indicates a second amount of current that is allowed to be drawn through the first charging equipment.
4. The method of claim 1 , further comprising:
cyclically reallocating electric current among the first charging equipment and the second charging equipment in a time period such that each of the first charging equipment and the second charging equipment receives an allocation of current in that time period while not exceeding the current capacity.
5. The method of claim 1 , further comprising:
receiving a second message that indicates that electric current allocation is no longer required at the second charging equipment; and
responsive to receiving that message, redistributing the electric current that is allocated to the second charging equipment to the first charging equipment.
6. The method of claim 1 , wherein adjusting the electric current allocated to the second charging equipment and allocating electric current to the first charging equipment is further based on a set of one or more charging session attributes associated with a first charging session for a first electric vehicle connected to the first charging equipment and a second charging session for a second electric vehicle connected to the second charging equipment, wherein the set of charging session attributes includes for each charging session one or more of charging session duration, type of account associated with that charging session, percentage of charging complete, percentage of charging remaining, battery temperature of the electric vehicle, priority of that charging session, and time remaining on that charging session.
7. An apparatus, comprising:
a controller coupled with a first charging equipment and a second charging equipment that share a current capacity, the controller configured to perform the following:
limit a total amount of current drawn through the first charging equipment and the second charging equipment to not exceed the current capacity including:
communicate a first current limit to the first charging equipment to cause a first electric vehicle to limit its current draw to not exceed the first current limit,
communicate a second current limit to the second charging equipment to cause a second electric vehicle to limit its current draw to not exceed the second current limit,
wherein a sum of current to be drawn at the first current limit and the second current limit does not exceed the current capacity.
8. The apparatus of claim 7 , wherein the communicated first current limit is to cause the first electric vehicle to limit its current draw to not exceed the first current limit through modulation of a first signal from the first charging equipment to the first electric vehicle to communicate the first current limit to the first electric vehicle, and wherein the communicated second current limit is to cause the second electric vehicle to limit its current draw to not exceed the second current limit through a modulation of a second signal from the second charging equipment to the second electric vehicle to communicate the second current limit to the second electric vehicle.
9. The apparatus of claim 7 , wherein the first current limit and the second current limit are substantially equal.
10. The apparatus of claim 7 , wherein the first current limit is less than the second current limit.
11. The apparatus of claim 7 , wherein the controller is further configured to reallocate current upon a determination that electric current is no longer required to be drawn by the first electric vehicle including to communicate a third current limit to the second charging equipment to cause the second electric vehicle to limit its current draw to not exceed the third current limit, wherein the third current limit is greater than the second current limit, and wherein current to be drawn at the third current limit does not exceed the current capacity.
12. The apparatus of claim 7 , wherein the controller is further configured to:
dynamically adjust the first current limit and the second current limit based on one or more of the following:
a percentage of charging completed by the first electric vehicle and the second electric vehicle;
a percentage of charging remaining of the first electric vehicle and the second electric vehicle;
a duration of charging of the first electric vehicle and the second electric vehicle; and
a type of account associated with the first electric vehicle and the second electric vehicle.