FIELD OF INVENTION

The present invention relates generally to charging stations and more particularly to a current control device for a charging station.

BACKGROUND

The operating temperature of a combustion engine is about 90° C. Even during a warm day the combustion engine will not be warmer than about 30° C during start up. At -20° C a combustion engine may consume as much as 80 liters per 100 kilometers. The consumption during starting temperatures is generally very bad and will thereby generate a substantially increased exhaust. By utilization of engine pre-heaters, the starting temperature of an engine can be increased. Both economical and environmental profits are substantial by increased utilization of engine pre-heaters.

Charging stations for vehicles will be a more common occurrence in the future, with the introduction of electrical vehicles and so called plug-in electrical hybrid vehicles (PHEV) . In Scandinavia, and in other cold winter areas, there is already a widespread use of electrical engine pre-heaters. Such stations can advantageously be used and expanded to be able to support more vehicles as the demand for charging stations will be increased for parked vehicles.

For a foreseeable future, electrical vehicles will have limited action range and need frequent charging. A problem with utilization of a charging station in connection with other equipment is that the charging station may in the short term consume a lot of power, which generally is solved by increasing the allowed rate of a main fuse, but it is very costly to have a high- rated main fuse for only short-term loading.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a control to a charging station, which charging station can be provided in connection with other loads having higher priority .

This object, among others, is according to the present invention attained by a current control device, a charging station and a current control method, respectively, as defined by the appended claims.

By providing a current control device for a charging station having a preferential load and a plurality of sockets, the current control device comprising current measurement means for measuring a preferential loading current, control means for controlling the plurality of sockets and an emergency circuit -breaker, wherein the control means is adapted to control a current loading the plurality of sockets in dependence of the preferential loading current, sporadic high loads can be managed at a charging station while maintaining operation of a prioritized load.

Preferably, for each separate phase in a three-phase system, total allowable current for the plurality of sockets is equal to a rated current of a main fuse for a main loading current minus actual current in the preferential load. Alternatively, for each separate phase in a three-phase system, total allowable current for the plurality of sockets is equal to a rated current of a main fuse for a main loading current minus actual current in the preferential load plus allowable momentary over- current for the main fuse .

Advantageously, the total allowable current is determined separately for each socket .

The emergency circuit -breaker is preferably arranged to disconnect all sockets from a main loading current when one separate phase, in a three-phase system, is overloaded. Alternatively, the emergency circuit -breaker is preferably arranged to disconnect one separate phase, in a three-phase system, when that main phase is overloaded .

With controllable socket loads, the control means is preferably adapted to firstly control one or more of the sockets to limit their respective load to not overload a main fuse for a main loading current and to secondly control the emergency circuit-breaker when the main fuse is overloaded.

Further preferred embodiments are defined by the dependent claims .

BRIEF DESCRIPTION OF DRAWINGS

The present invention will become more fully understood from the detailed description of embodiments given below and the accompanying drawings, which are given by way of illustration only, and thus, are not limitative to the present invention, in which:

Fig. 1 schematically shows a charging station comprising a current control device according to a first embodiment of the present invention. Fig. 2 schematically shows a method for current control of a charging station according to the present invention.

Fig. 3 schematically shows a charging station comprising a current control device, including an emergency circuit - breaker according, according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description, for purpose of explanation and not limitation, specific details are set forth, such as particular techniques and applications in order to provide a thorough understanding of the present invention. However, it will be apparent for a person skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed description of well-known methods and apparatuses are omitted so as not to obscure the description of the present invention with unnecessary details.

A current control device for a charging station according to the present invention will now be described with reference to Figs. 1-2.

The charging station comprises a main fuse 1, a preferential load 4, a plurality of sockets 5-8, and the current control device. The current control device includes current measurement means 2 and an emergency circuit-breaker 3. The charging station is e.g. a parking area outside a mall, wherein the mall is the preferential load.

The current control device is arranged to measure a preferential loading current flowing to the preferential load 4, which preferential loading current at least partly loads the main fuse 1 for a power supply to a user installation. The current is measured in an appropriate conventional way. The current flowing through the main fuse 1 is due to loading from the preferential load 4 and loading from the plurality of sockets 5-8.

The emergency circuit -breaker 3 is e.g. implemented by means of a relay switch.

Each socket 5-8 comprises one of the following devices: a controllable three-phase charging socket; a controllable three-phase socket; an uncontrollable three-phase charging socket; an uncontrollable three-phase socket; a controllable one-phase charging socket; a controllable one-phase socket; an uncontrollable one-phase charging socket; an uncontrollable one-phase socket.

During operation the current control device monitors 9 the current flowing to the preferential load 4. The current control device then distributes current consumption rights to the sockets, equal to the difference between the rated current of the main fuse 1 and the current currently flowing to the preferential load 4. Alternatively, temporal overloading of the rated current of main fuse 1 is distributed, taking into account expected properties of the fuse. The current control device then monitors the current flowing to the sockets, to secure that the current consumption rights are not exceeded. If the current flowing to the sockets exceeds the current consumption rights the emergency circuit -breaker is requested to break the current to the plurality of sockets. Also, if a socket does not consume its distributed current, redistribution of that right is performed . Reset of the emergency circuit -breaker is preferably performed when available current is enough for expected loading of at least one controllable socket.

By the term charging socket is meant a connector adapted for charging a PHEV. By the term socket is meant a regular connector e.g. for connection of a pre-heater or other vehicle mounted current consumer such as coupe cooling. A typical electrical engine pre-heater with a coupe fan is connected to a single phase and consumes about 2 kW corresponding to approximately 10 A. A typical PHEV is connected to a single phase and controllably consumes between 2-3 kW, corresponding to 10-14 A. A suggested future quick charging standard for electrical vehicles is connected to three phases and controllably consumes up to 43 kW, corresponding to 63 A. The today highest rated end fuse for a 400 V system in Sweden is 216 A.

During a variant of operation the current control device monitors the main loading current flowing through the main fuse. When the total load of the charging station draws a current equal to or above the rated current of main fuse, and the plurality of sockets comprises a controllable load, one or more of these controllable loads are requested to reduce its respective load. When the plurality of sockets does not comprise a controllable load, or when the possible reduction of load is not enough to reduce the main current below the rated current, the emergency circuit -breaker is requested to break the current to the plurality of sockets.

A second embodiment of the present invention is shown in Fig. 3, which is identical with the first embodiment of the present invention described above apart from that the emergency circuit -breaker is comprised within the current control device 2, and also that the figure illustrates the three phases of the power grid separately from each other, for lines la, lb and lc respectively.

Loading equipment 13 illustrates a controllable three- phase charging socket. Loading equipment 14 illustrates a controllable three-phase socket. Loading equipment 15 illustrates a controllable one-phase socket connected to line a. Loading equipment 16 illustrates a controllable one-phase socket connected to line b. Loading equipment 17 illustrates an uncontrollable one-phase socket connected to line c. Loading equipment 18 illustrates a controllable one-phase charging socket connected to line a. Loading equipment 19 illustrates an uncontrollable one-phase charging socket connected to line b. Loading equipment 20 illustrates a controllable one-phase socket connected to line c. Loading equipment 21 illustrates an uncontrollable three-phase socket.

The emergency circuit-breaker preferably disconnects all three phases at the same time. However, e.g. when only one-phase sockets are used in a charging station the emergency circuit -breaker disconnects a single phase when overloaded. Reset of the emergency circuit -breaker works in a corresponding way.

Fig. 4 shows a vehicle charging communication interface 41. A charging station socket 42 and a single vehicle socket 43 are shown. The current consumption of the charging station is controlled by a CP-pin, Control Pilot signal pin 45. By this signal, the onboard charger or the external charger can be controlled. The current control device includes a charge grid controller (not shown) calculating a value for the vehicle. Such value is used to control the current provided to the vehicle to be charged. The value is calculated from data regarding the current load situation in the specific charging station. Such data may be capacity of a main fuse 1 for the system as a whole as well and present load current delivered to a preferential load 4 comprised in the system, and the current capacity of a vehicle charging cable used. A Proximity Pin PP 44, also known as Plug Present, provides information of the current capacity of the vehicle charging cable. According to standard IEC 62196- 2, this pin 44 shall be present in current charging devices for vehicles; a resistor is connected to the pin 44 at both connectors of the cable, and the size of such resistor corresponds to the current capability of the present cable connected between the vehicle socket 43 and the charging station socket 42. Thereby, the current capacity of the present cable is provided to the current control device.

The charging current actually delivered to the vehicle by the current control device is thus taking into account the current available depending on other, preferential loads in the system, and the maximum current that may be delivered via the vehicle charging cable used.

The power transmission between the charging station and the vehicle is achieved via a connection 46. Such connection may comprise 3-5 connectors, connected to a 400V AC power system. It will be obvious that the present invention may be varied in a plurality of ways. Such variations are not to be regarded as departure from the scope of the present invention as defined by the appended claims. All such variations as would be obvious for a person skilled in the art are intended to be included within the scope of the present invention as defined by the appended claims.