CHARGING SYSTEM FOR DC CHARGING THE TRACTION BATTERY OF AN ELECTRICALLY POWERED MOTOR VEHICLE

Description

[0001] The invention relates to a charging system for direct current charging of the traction battery of an electrically powered motor vehicle, comprising a stationary charging station which is connected to a three-phase AC or three-phase power supply network, with at least two AC / DC converters, wherein an AC / DC converter is designed as part of a portable module which can be removed from the charging station, which module is provided with a housing which can be separated from the charging station and in which further electronic components are present which supplement it to form a standalone, single-phase DC charger which is independent of the stationary charging station and which can be connected on the input side to any single-phase AC power supply, and wherein the direct current generated in the portable module is combined with the internally generated direct current, so that on a DC charging cable of the stationary charging station which is connected to the motor vehicle,all the direct current generated is available.

[0002] The term "electrically powered motor vehicle" refers to vehicles that are powered either exclusively or additionally by electric motors and that, at least optionally, provide the option of charging from an external power source. In particular, so-called plug-in hybrid vehicles are also considered electric vehicles.

[0003] For the wired charging of electric vehicles, alternating current (AC) and direct current (DC) charging have become established as possible charging modes. With AC charging, a single-phase or multi-phase alternating current is supplied to the electric vehicle via a cable. An AC / DC converter in an on-board charger converts this alternating current into direct current, which is then fed to the traction battery. Fully charging a discharged traction battery typically takes several hours.

[0004] With direct current charging, the electric vehicle is supplied with direct current at a charging station. The traction battery can be connected directly to the charging station, usually via a mechanical or electronic disconnect switch, but without the use of on-board converter circuits, which are subject to strict space and weight restrictions. This makes it possible to provide significantly higher currents during charging than with alternating current charging, allowing the charging process to be comparatively fast, as the stationary charge controller, in the form of a charging station or wallbox, can be designed significantly larger than the on-board charger.

[0005] Eliminating these on-board converter circuits, which are components of so-called "onboard chargers," also offers significant cost advantages. However, these vehicles are then only equipped with a DC charging option and are therefore dependent on corresponding DC charging stations. However, if such a vehicle is driven far from suitable charging infrastructure, there is a need for a portable charging option that allows the vehicle to be charged both at public AC charging stations and at home.

[0006] US 2013 / 0049689 A1 discloses a charging system for charging the traction battery of an electrically powered motor vehicle, wherein the charging system is configured for both direct current and alternating current charging. The charging system also includes an AC / DC converter configured to charge a storage battery within a mobile charging station with power from the alternating current grid. A module removable from the charging station is provided with a housing and electronic components that make it a standalone single-phase charger. However, this charger is only suitable for alternating current charging. The vehicle therefore still requires an onboard charger in any case.

[0007] DE 10 2015 200 960 B4 shows a charging system according to the preamble of patent claim 1. This charging system has a portable module that can be removed from the stationary charging station, which is provided with a housing that can be separated from the charging station, and represents a standalone DC charger that is independent of the stationary charging station and can be connected on the input side to any 1-phase AC power supply.

[0008] The present invention further develops such a charging system for direct current charging of the traction battery of an electrically powered motor vehicle in such a way that a particularly practical and cost-effective design is possible through a clever division of components between the stationary and mobile parts.

[0009] This is achieved according to the invention in that there is a separate AC / DC converter for each of the three phases, and in that the direct current generated in the portable module from a first phase is combined with the direct current generated internally from the other two phases.

[0010] By combining the direct current generated from one phase in the portable module with the direct current generated internally from the other two phases, so that the direct current generated from all three phases is available on a DC charging cable of the stationary charging station, which is connected to the vehicle, the components for filtering, rectification, power factor correction, galvanic isolation and current regulation of one phase can be eliminated in the stationary charging station.

[0011] The portable module itself, with its integrated AC / DC converter, represents a standalone DC charger independent of the stationary charging station, which can be connected to any single-phase AC power supply on the input side.

[0012] Further advantageous embodiments of the subject matter according to the invention are specified in the dependent claims and are explained in more detail with reference to an embodiment shown in the drawing. Fig. 1: a charging system according to the invention as a so-called wallbox with a holder for the portable module with a separate and with an inserted portable module Fig. 2: a schematic representation of the electrical components of the charging system according to the invention

[0013] As shown in the drawing, the stationary charging station 1 of the charging system according to the invention comprises a docking station with a stable housing, which is attached, for example, to a wall. Electrically, this docking station of the stationary charging station 1 is permanently connected to a three-phase power supply. The docking station has a long cable 6 with a suitable plug 7 for DC charging of an electric vehicle, as well as a control option. The connection to the power grid consists of three phases L1, L2, L3, the neutral conductor N, and the protective earth PE. Within the stationary charging station 1, the phases L1, L2, L3 are split, with the alternating current from two of these phases L2, L3 being converted to direct current in internal AC / DC converters. The first phase L1 is connected to a plug, which, as soon as the portable module 2, as shown in the two figures in Fig. 1shown, is plugged into the stationary charging station 1 and engages an AC input socket of the portable module 2 via the interface 2'.

[0014] Thus, the portable module 2 is connected to a single-phase AC power supply L1, N, PE and can, in turn, convert the current from this single phase L1 from AC to DC using an AC / DC converter 3 integrated into the portable module 2. This DC current is fed back into the stationary charging station 1 via a DC output plug of the portable module 2 via the detachable connection 2. There, the direct current generated from this single phase L1 is combined with the direct current generated internally from the two other phases L2, L3, so that the direct current generated from all three phases L1, L2, L3 is available at the thicker DC charging cable 6 of the docking station, which is connected to the vehicle.

[0015] Independent of the stationary charging station 1, the portable module 2 with its integrated AC / DC converter 3 also represents a standalone DC charger that can be carried in the vehicle if necessary. Its input can be connected to any single-phase AC power supply, be it that of a public AC charging station or a domestic socket. The DC output of the portable module 2 is in turn connected directly to the vehicle's charging input. It is also possible, for example, to provide a permanent slot for the portable module 2 in the trunk of the vehicle, where it can be safely transported and is already permanently electrically connected between an AC input of the vehicle and a DC input, so that for charging only the connection to the AC input of the vehicle needs to be established from the outside.

[0016] The charging system according to the invention enables the user, depending on how the vehicle is used, to decide whether to carry the portable module 2 in the vehicle in order to be able to charge the traction battery regardless of the accessibility of a suitable stationary DC charging station, or whether to forego it in order to save additional weight and increase the available storage space and to benefit from the increased charging capacity of the combined wallbox, for example when only short distances are covered with the vehicle.

Claims

1. Charging system for DC charging the traction battery of an electrically powered motor vehicle, comprising a stationary charging station (1) which is connected to a three-phase alternating voltage or three-phase current supply network (L1, L2, L3, N, PE), with at least two AC / DC converters (3, 4, 5), wherein one AC / DC converter (3) is designed as part of a portable module (2) that can be removed from the charging station (1), which module (2) is provided with a housing that can be separated from the charging station (1), in which further electronic components are provided which supplement it to form a stand-alone, single-phase DC charger independent of the stationary charging station, which can be connected on the input side to any single-phase AC power supply, and wherein the direct current generated in the portable module (2) is combined with the internally generated direct current so that the entire direct current generated is available at a DC charging cable (6) of the stationary charging station (1) which is connected to the motor vehicle, characterized in that, that there is a separate AC / DC converter for each of the three phases (L1, L2, L3), and that the direct current generated in the portable module (2) from a first phase (L1) is combined with the direct current generated internally from the other two phases (L2, L3).