Charging device for electric vehicles
By segmenting the DC bus and incorporating buffer storage and a ring circuit, the charging device addresses inefficient load balancing, ensuring faster charging and efficient power utilization across charging stations.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- JOHN DEERE ELECTRIC POWERTRAIN LLC
- Filing Date
- 2025-12-17
- Publication Date
- 2026-07-02
AI Technical Summary
Existing charging devices for electric vehicles suffer from inefficient load balancing when vehicles are unevenly distributed across charging stations, leading to slow charging at some stations and underutilization of available power at others.
The DC bus is segmented using an isolation unit, allowing selective distribution of converter output power to balance load across charging stations, with features like buffer storage units, DC-DC converters, and a ring circuit to manage fluctuating power demands and failures.
Enables faster charging at heavily utilized stations and more efficient use of available power by redistributing power from less busy stations, improving reliability and reducing line losses.
Smart Images
Figure EP2025087742_02072026_PF_FP_ABST
Abstract
Description
[0001] Charging device for electric vehicles
[0002] Technical field
[0003] The invention relates to a charging device for electric vehicles with a charging station comprising a converter connected on the input side to a mains connection and on the output side to a distributor, wherein the distributor is connected to both a charging connection and a DC bus leading from the charging station.
[0004] State of the art
[0005] Charging devices for electric vehicles with grid connection, converter, charging port and DC bus are known from the state of the art.
[0006] For example, US20220410755A1 shows a charging device which, in the event of a failure of a single charging station, enables power to be supplied to the charging port by a neighboring charging station via the DC bus.
[0007] Furthermore, US20220410755A1 provides for two converters and two distributors per charging station. In the case of a freestanding distributor to which no electric vehicle is connected, the charging power of both converters at one charging station can be supplied to the other distributor. A disadvantage of this charging device is that if the electric vehicles are unevenly distributed across the charging stations, the charging power of individual charging stations must be divided among many vehicles, resulting in slow charging while the charging power of other charging stations remains unused.
[0008] Description of the invention
[0009] The invention is therefore based on the objective of proposing a charging device that enables improved load balancing in the case of an uneven distribution of electric vehicles across the charging points. The invention solves this problem by routing the DC bus from a DC bus input through a isolating unit to a DC bus output through the charging station. The invention is based on the consideration that, in charging stations, the converters used, which, for example, convert alternating current from a power grid into direct current or direct current from a buffer storage system into direct current, are the limiting factor with regard to the power available at the charging point.According to the invention, the DC bus, or, with the isolation unit activated, a segment of the DC bus, can be powered by the converter. This allows the converter's output power to be selectively made available to other components connected via the DC bus when the output power is not, or only partially, delivered via the charging port. The ability to isolate the DC bus offers the advantage that the converter's output power is delivered only via one segment of the DC bus, while the isolated segment is available for independent load balancing. For example, the DC bus can be divided into several segments using the isolation unit, thus enabling load balancing between the charging stations within a segment.This allows the charging power of less busy charging stations to be distributed via the DC bus when individual charging stations are heavily utilized, thus enabling faster charging at the heavily used stations and more efficient use of the total available output power of the available converters. According to the invention, a distributor is understood to be a circuit arrangement that selectively distributes the output power of the converter to the charging port and / or the DC bus, or directs the power available via the DC bus to the charging port. In the case of a bidirectional converter, the power available on the DC bus can be selectively distributed to the charging port and / or to the converter via the distributor. In a preferred embodiment, at least two further charging stations are connected to the described charging station via the DC bus.In this case, the isolation unit according to the invention can selectively supply a single charging station with the charging power of the other charging stations, isolate one charging station from the other two connected charging stations, or divide the DC bus into three individually supplied charging stations. With the isolation unit activated, the distributor can selectively connect the converter to either of the two DC bus segments. In one embodiment, a charging station can also have two isolation units, enabling the DC bus to be isolated on both sides of an intermediate feed-in point. The charging station can be a charging column forming a single unit. The charging device according to the invention can, for example, be a charging location where several charging stations, preferably charging columns, are connected to a DC bus.
[0010] To enable the provision of temporarily high charging power despite a limited grid connection, it is proposed that a buffer storage unit be provided, connected to the converter. This allows the buffer storage unit to be charged over a longer period using the converter when power demand is low, while the energy stored in the buffer storage unit can be released to cover peak demand at the charging point over shorter periods, preferably in addition to the energy fed in via the grid connection. To compensate for fluctuating power demand across multiple charging stations, it is proposed that the charging device include a storage bus in addition to the DC bus, which allows for adjustment of the charge levels of the buffer storage units.To adjust the voltage level of the buffer storage device, an additional DC-DC converter can be provided between the converter and the buffer storage device. In a preferred embodiment, each charging station includes at least one buffer storage device.
[0011] A charging current advantageous for charging electric vehicles at the charging port can be achieved if the converter includes at least one AC-to-DC converter. This means that every charging station includes at least one AC-to-DC converter. This allows alternating current from the power grid to be converted into a suitable direct current for the charging process. In a preferred embodiment, the AC-to-DC converter can provide a charging voltage to supply a buffer storage device. The AC-to-DC converter can preferably be directly connected to the distribution board. In order to be able to release excess energy available in the charging device to the power grid at a suitable time, for example, the AC-to-DC converter can be bidirectional.The flexibility in the design of a charging device according to the invention is further increased by providing a converter bus before and / or after the AC-DC converter. This allows the...
[0012] The AC power before the AC-to-DC converter and / or the DC power after the AC-to-DC converter are distributed between the individual charging stations. A converter that includes an AC-to-DC converter can particularly improve reliability, since each charging station has its own converter and thus an AC-to-DC converter. This allows each charging station to be directly connected to an AC grid, so that even if one AC-to-DC converter fails, the charging connections of all charging stations can continue to be supplied via the DC bus. In a preferred embodiment, the charging device comprises at least two charging stations, each with a converter that includes an AC-to-DC converter.
[0013] To specify the required voltage level at the charging port independently of any buffer storage used, as well as requirements for conductor cross-sections and insulation, it is proposed that the converter include at least one DC-DC converter. Furthermore, to allow the charging port voltage level to be adjusted to the changing state of charge of the electric vehicle being charged, the DC-DC converter can have an adjustable conversion ratio. To enable the simultaneous charging of multiple electric vehicles at a charging station, the station can have multiple charging ports. In this context, one, and in particular two, DC-DC converters can be provided for each charging port. This allows the voltage levels at the charging ports to be adjusted independently to the respective electric vehicle.Multiple DC-DC converters per charging port increase the charging power available at the charging port without requiring more installation space and / or increasing the cost per DC-DC converter. For improved reliability and to avoid system bottlenecks, it is preferable to have one converter per charging port, optionally comprising an AC-DC converter and / or one or more DC-DC converters.
[0014] In one embodiment, at least one expansion unit can be provided, which includes a converter with a mains connection and / or a charging connection, wherein the expansion unit is also connected to the DC bus and preferably includes an isolation unit for this bus. The expansion unit can be implemented without a DC-DC converter.
[0015] To increase both the redundancy and efficiency of the charging system, it is proposed that the DC bus be routed as a ring circuit through several charging stations. In the event of a failure of individual charging stations or sections of the DC bus, load balancing can still be maintained via the ring circuit, as power transmission can continue via the undamaged portion of the ring. Furthermore, the ring circuit reduces line losses in the DC bus, as the current path can be distributed across multiple line segments compared to simpler bus structures.
[0016] Brief description of the invention: The invention is illustrated by way of example in the drawing. It shows...
[0017] Fig. 1 shows a schematic representation of a charging device with three charging stations in a first operating state,
[0018] Fig. 2 shows a detailed view of a charging station from Fig. 1 on a larger scale, Fig. 3 shows a representation corresponding to Fig. 1 in a second operating state and
[0019] Fig. 4 shows an alternative embodiment of the charging device corresponding to Fig. 1, with a converter bus, a storage bus and two expansion units.
[0020] Ways to implement the invention
[0021] In a charging device according to the invention, electric vehicles 1a, 1b, 1c are connected to charging stations 2a, 2b, 2c for charging their own batteries. The charging stations 2a, 2b, 2c are each supplied with external energy via a mains connection 3. The energy is routed from the mains connection 3 via a converter 4 to a distributor 5 and then to a charging port 6a-f. Alternatively or additionally to the charging port 6a-f, the distributor 5 can route the energy to a DC bus 7, which runs from a DC bus input 8 via a isolating unit 9 to a DC bus output 10 through the charging station 2a, 2b, 2c.
[0022] The charging station 2a, 2b, 2c can have a buffer storage unit 11, which can be charged at the charging ports 6a-f when the load is low and discharged when the energy demand is high.
[0023] As can be seen particularly in Fig. 2, the converter 4 can comprise an AC-DC converter 12 and / or a DC-DC converter 13. In the embodiment shown, the charging station 2a comprises two charging ports 6a, 6b and two converters 4, each with one AC-DC converter 12 and two DC-DC converters 13. To illustrate the different operating states of the charging device according to the invention, Figs. 1 and 3 show the same charging device in different operating states by way of example, with the arrows schematically indicating the energy flow.
[0024] In Fig. 1, five charging ports 6a, 6c, 6d, 6e, 6f are occupied by electric vehicles 1a, which have a low energy demand 14a. The energy that would be available for the unused charging port 6b can, in this case, be used to charge the buffer storage 11. Since there is no increased energy demand at individual charging ports 6a-f, the isolation units 9 of the different charging stations 2a, 2b, 2c can divide the DC bus 7 into individual segments.
[0025] In the operating state shown in Fig. 3, an electric vehicle 1b with high energy demand 14b is connected to the previously unused charging port 6b of charging station 2a. At another charging station 2b, in the operating state shown in Fig. 3, only an electric vehicle 1c with medium energy demand 14c is connected to charging port 6c; charging port 6d remains unused. At the third charging station 2c, an electric vehicle 1a with low energy demand 14a is connected to charging port 6e, and charging port 6f remains unused.
[0026] To meet the high energy demand 14b of the electric vehicle 1b, a portion of the energy from charging station 2c can be routed to the DC bus 7 via distributor 5. In the example shown, the isolating unit 9 connects charging station 2c to charging station 2a, forming a load-balancing segment. This allows for an increased energy supply to the high-demand electric vehicle 1b at charging port 6b. Additionally, the previously charged buffer storage 11 of charging station 2a can provide increased energy for the high-demand electric vehicle 1b. Charging port 6c, serving the medium-demand electric vehicle 1c, can be supplied via distributor 5 by both converters 4 of charging station 2b, thus enabling a higher charging power here as well.
[0027] In the drawing, the energy requirement 14a-c is shown schematically as the battery charge state of the electric vehicles 1, however, the energy requirement 14a-c can also result, for example, from the maximum charging power of the individual vehicle models or from the planned charging time of the electric vehicles 1 ac.
[0028] Figure 4 shows an alternative embodiment in which expansion units 15a, 15b are provided for the charging device. The expansion units 15a, 15b are connected to the charging stations 2a, 2b via the DC bus 7 and each has a charging port 6g, 6h. Each expansion unit 15a, 15b can have a disconnect unit 9 for the DC bus 7, so that the expansion units 15a, 15b can be connected to the different segments to enable increased charging power at the charging ports 6g, 6h of the expansion units 15a, 15b. At least one expansion unit 15a can have a converter 4 and a mains connection 3.
[0029] As shown in Fig. 4, the charging device for adjusting the charge states of the buffer storage units 11 can have a storage bus 16. Isolation units 9 can be provided in the storage bus 16 for coupling and decoupling the buffer storage units 11 from each other.
Claims
Patent claims 1. Charging device for electric vehicles (1 ) with a charging station (2) comprising a converter (4) connected on the input side to a mains connection (3) and on the output side to a distributor (5), wherein the distributor (5) is connected both to a charging connection (6) and to a DC bus (7) leading from the charging station (2), characterized in that the DC bus (7) is led from a DC bus input (8) via a isolating unit (9) to a DC bus output (10) through the charging station (2) and that the converter (4) comprises at least one AC-DC converter (12).
2. Charging device according to claim 1, characterized in that a buffer storage device (11) is provided which is connected to the converter (4).
3. Charging device according to one of claims 1 or 2, characterized in that the converter (4) comprises at least one DC-DC converter (13).
4. Charging device according to one of claims 1 to 3, characterized in that the charging station (2) comprises several charging ports (6).
5. Charging device according to one of claims 1 to 4, characterized in that the DC bus (7) is routed as a ring line through several charging stations (2).