GB2524161A

GB2524161A - Trailer having a solar generator

Info

Publication number: GB2524161A
Application number: GB1501980.5A
Authority: GB
Inventors: Austin Shinkle; Ernesto Grundseth; Jason Luecht
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2015-02-06
Filing date: 2015-02-06
Publication date: 2015-09-16
Also published as: GB201501980D0

Abstract

A trailer 10 adapted to be coupled with a tractor 12, the trailer having a solar generator 14, an energy converter 16 connected with the solar generator and a first electrical connector 18 electrically connected with the energy converter and adapted to be coupled with a respective second electrical connector 20 of the tractor, wherein the first and second electrical connectors allow energy transfer from the trailer to the tractor when in a connected status, wherein the energy converter is adapted to convert electrical energy supplied from the solar generator and to make the converted electric energy available at the first electrical connector by providing a voltage at the first electrical connector and wherein the energy converter is adapted to detect the connected status and to provide the voltage in the connected status only.

Description

Intellectual Property Office Application No. GB1501980.5 RTN4 Date tO August 20t5 The following term is a registered trade mark and should be read as such wherever it occurs in this document:

SI KAFLEX

Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo Trailer having a solar generator The present invention relates to a trailer adapted to be coupled with a tractor, the trailer having a solar generator, an energy converter connected with the solar generator, and a first electric connector electrically connected with the energy converter and adapted to be coupled with a respective second electric connector of the tractor, wherein the first and the second electric connectors each have at least two respective power contacts in order to allow energy transfer from the trailer to the tractor in a connected status, wherein the energy converter is adapted to convert electric energy supplied from the solar generator and to make the converted electric energy available at the at least two power contacts of the first electric connector by providing an electric voltage between the at least two power contacts of the first connector.

A generic trailer is known from US 2010/0141201 Al. to Littrell et al. The trailer disclosed is suited for delivering electric energy to an electric vehicle coupled thereto. The electric vehicle includes a charging controller and a battery. On the trailer are arranged a plurality of solar cells which, when excited to solar light, generate electric power. The trailer further comprises a power converter connected with the solar cells and accumulating the generated electric power. The power converter converts the received electric power and supplies the converted energy to a connector that couples the converter to the charging controller of the electric vehicle in the coupled status.

However, practical use of such trailers is connected with some risk of electrocution. The risk appears especially when coupling the trailer to the tractor or decoupling the trailer from the tractor. Moreover, if the trailer is in a decoupled status and the solar cells are exposed to solar light, there appears a high voltage at the connector which is dangerous in operating and may cause electroshock to a user in the range of the connector.

Additionally, if the trailer is installed in the range of a parking area or the like, the connector may be exposed to environmental and/or atmospheric conditions which may affect the electric insulation, especially in the range of the connector. This may cause electric interferences which may damage the electric installation of the trailer.

Therefore, it is an object of the invention, to improve safety of a trailer.

The object is solved by a trailer according to claim 1. Further aspects of at least some exemplary embodiments of the aspects of the invention are set out in the respective dependent claims.

According to a first aspect, the energy converter of the trailer is adapted to detect the connected status and to provide the electric voltage in the connected status only.

The tractor is generally a propelled vehicle that is driven by use of at least one electric machine. The vehicle includes for this purpose at least one or more electric motors or engines, respectively that are used to provide propulsion to the vehicle. Electric energy used to propel the electric vehicle may come from various sources, such as, but not limited to, an on-board rechargeable battery, and/or an on-board fuel cell. In one embodiment, the electric vehicle is a hybrid electric vehicle that uses not only an electric machine for propulsion but may also use a combustion engine for propulsion. The electric machine and the internal combustion engine may provide propulsion of the vehicle in combined operation or they may provide propulsion only if the other engine is not operating. An electric vehicle may further use electric energy which is stored in an electrical source such as a battery or an accumulator, respectively, in order to continue operating when idling to conserve fuel for the internal combustion engine. The hybrid vehicle may further be capable of recharging the battery by plugging into a power receptacle, such as a general power outlet. Accordingly, the electric vehicle may refer to a vehicle that uses electric energy for propulsion.

A trailer generally is a non-propelled vehicle which is adapted to be coupled to the tractor.

The trailer may refer to a transport conveyance that is designed to be pulled by the tractor which, in turn, is preferably an electric vehicle. Moreover, the trailer may have a portable platform that may be coupled and decoupled to the tractor. Consequently, the trailer may further refer to any moveable or rolling platform that may be coupled to the tractor.

The solar generator is an apparatus that is mounted on the trailer, for example, on a roof of the trailer. Preferably the roof of the trailer is a flat surface that is substantially horizontally arranged during determined operation of the trailer. The solar generator may comprise solar cells that are connected in a manner in order to provide electric energy at a predetermined electric voltage. In this regard, the solar generator is an apparatus that converts light energy, such as the energy of solar light, received to electric energy provided at connectors of the solar generator. In this regard, the solar cells may be arranged in solar panels forming preferably integral components. The solar cells of a solar panel are respectively connected with each other. Preferably, the solar panels are arranged on the roof of the trailer so that they can be easily exposed to solar light.

The solar cells and/or the solar panels, respectively, may comprise a semiconductor material that is suited for energy conversion from light energy to electric energy, such as silicone or the like. Preferably, the semiconductor material may be a copper indium gallium selenide material.

The first electric connector of the trailer is adapted to be connected with a respective second electric connector of the tractor when the trailer is coupled to the tractor. In this regard, according to one exemplary embodiment, the first electric connector may be a plug and the second electric connector may be formed by a receptacle. However, in an alternative exemplary embodiment, the first electric connector may be formed as a receptacle, wherein the second electric connector may be formed as a plug. Preferably, the first electric connector may comprise a connector cable that comprises electric wires in order to allow establishing an electric connection between the trailer and the tractor in the coupled status. For this purpose, each of the first and the second connectors have at least two respective power contacts that contact each other when the first and the second electric connectors are connected with each other. In this way, the electric connection between the trailer and the tractor can be established. The power contacts are adapted to lead a sufficient electric current that may flow in order to transfer the electric energy from other trailer to the tractor.

The trailer further comprises the energy converter which is an apparatus that is electrically connected to the solar generator, the solar panels, or the solar cells, respectively. The energy converter is adapted to convert the electric energy supplied from the solar generator such that it is suited to be used by the tractor. In this regard, the energy converter may comprise a DC/DC-converter. Therefore, the energy converter makes the converted electric energy available at the at least two power contacts of the first electric connector by providing an electric voltage between the at least two power contacts of the first connector. In the connected status of the first and the second connectors, the voltage between the two power contacts of the first connector is transferred to the respective at least two power contacts of the second electric connector so that the electric energy is made available at the tractor's site.

According to the first aspect of the invention, the energy converter is adapted to detect the connected status. In this regard, the energy converter may detect whether the trailer is coupled to the tractor. Only if the coupling is detected, the energy converter provides the electric voltage at the power contacts of the first connector. So, in the disconnected status to the decoupled status, respectively, the power contacts of the first connector are not subjected to electric voltage so that safety, especially with regard to electrocution, can be improved.

Features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of an exemplary embodiment described with regard to the accompanying drawings are supposed to be not only be used in the respective specified combination but also in other combinations or alone, without departing from the scope of the invention. Thus, combinations are also to be considered as being encompassed and disclosed by this description which are not explicitly shown in the figures or explained in detail but arise from and can be derived from this specification by those skilled in the art.

Further advantages, features and details of the invention will become apparent by the following description of an embodiment under consideration of the accompanying drawings. In the drawings, equal reference characters relate to equal features and functions.

In the drawings show: Fig. 1 a schematic top view of a trailer according to the invention having a solar generator; Fig. 2 a schematic side view of the trailer according to Fig. 1; Fig. 3 a schematic front view of the trailer of Fig. 1; Fig. 4 a schematic electric diagram of the trailer according to Fig. 1 coupled to a tractor; Fig. 5 a discharge circuit according to the invention in a schematic electric diagram; Fig. 6 a schematic electric diagram of the connections between the trailer in a coupled status with the tractor; and Fig. 7 a schematic sectional view of a connector having two power contacts.

The invention uses safety requirements for electric and plug-in-hybrid vehicles such as tractors and adds several key aspects.

The invention allows using solar energy for energy supply of a tractor 12 while a trailer 10 is coupled to the tractor 12, stationary as well as moving. While stationary charging systems of the art provide an interlock of the vehicle side, in the form of an electronic immobilizer to make sure that the vehicle is not moving, this requirement is not necessary for the solar trailer 10 implementation according to the invention. While safely disconnecting the system under normal operations or abuse remains a key requirement, the fact that the system must charge while the vehicle is moving does not lend itself to using the bulk stationary electric charger connection that is used in conventional systems.

Vibration requirements of a moving vehicle lead to use of multiple automotive grade connectors to achieve signal transmission and high voltage power transmission between the tractor 12 and the trailer 10. Multiple connections mean that the connection interlock circuit must take into account multiple connectors and not a single charging plug. As the system spans a gap and both the tractor 12 and the trailer 10 have connections, the system must shut down in the event that the charger, that is the trailer 10, or the vehicle, that is the tractor 12, side is disconnected. This is in contrast to stationary chargers as the charging cable is permanently connected to the charger and only the vehicle may be disconnected.

Moreover, as the charger, the trailer 10, is exposed to the elements as well as cargo that is loaded and unloaded, there is potential for the charger to become electrically compromised. Therefore, while the system is being operated, it is supposed to use charger control electronics for constantly monitoring the insulation of solar panels 42 to the trailer 10 and will shut down the system and report an error code if the insulation reaches a point to where it may be dangerous to a user.

As the system is designed to be used by a user of any skill level, the system may use in an exemplary further embodiment an air supply to the trailer 10 to make an informed decision that the user may be preparing to decouple the trailer 10 from the tractor 12.

This loads the charging system to proactively shutdown while the driver of the tractor 12 is still in the tractor 12 to protect the user from electrocution as well as to protect the system components from damage from being disconnected while the system is supplying power.

Fig. 1 shows schematically a top view of the trailer 10 according to the invention. The trailer 10 has a roof 56 upon which fifteen solar panels 42 are mounted which in turn forms a solar generator 14. Fig. 2 shows the trailer 10 in a schematic side view, whereas Fig. 3 shows the trailer 10 in a schematic front view. In Figs. 2 and 3 is further depicted a solar battery charger (SBC) 16 forming an energy converter. The solar battery charger 16 is located inside the trailer 10 and is connected to the solar panels 42 as further detailed with reference to Fig. 4.

The solar panels 42 are made of flexible copper indium gallium selenide. In this exemplary embodiment, these panels 42 are chosen over silicone as they are significantly lighter in weight. While silicone panels have a much higher power output, it was decided that the extra weight carried extra freight efficiency risk in the case that the system was run on a cloudy day. Regardless of the power output of the system, the weight is always a penalty. In addition, silicone panels are extremely fragile. The risk that such panels would be damaged due to mounting on a commercial vehicle is greater than by the chosen panels 42.

In the preferred embodiment the mechanical dimension of each panel 42 is 2450 mm x 993 mm x 3 mm. The width and the height are set values and the value of 2450 mm is optimized for the trailer 10 used. A standard 53' dry box van trailer roof surface area is 16.1 m x 2.75 m. This lends itself to easily mount the fifteen solar panels 42 of the before mentioned dimensions as seen in Fig. 1. The 3 mm height of the panel is such that the overall height of the trailer as well as the aerodynamic surface remains largely unchanged. This would not have been true for silicone panels. The panels 42 are attached with adhesive such as SikaFlex that provides bonding and water sealant. It is the same material that is used during trailer construction and has a proven track record for this type of application. However, in other embodiments, another adhesive may be used.

In further alternative embodiments, the solar panels 42 may also be connected with the root 56 by mounting clips, claws, and/or the like. The electric wiring for the solar panels 42 is on the bottom of each of the panels 42 and enters the trailer 10 through a hole in the roof 56 under one of each of the panels 42. In this embodiment, the roof 56 is made from fiber glass. The wires are run along the top of the inside of the trailer 10 to its front where it is joined in a junction box 44.

The solar battery charger 16 is attached at the front of the trailer 10 on rubber bumpers 58 in order to alleviate vibration due to the rough mounting environment of a commercial trailer as the trailer 10. The junction box 44 is mounted on a trailer wall in order to provide a bus point for the solar panels 42 which are connected so as to form five sets, as further detailed below. Additionally, the junction box 44 can be locked to prevent unauthorized access to the electrical connections which may be subjected to an electric voltage of about 100 V in this embodiment.

As can be derived from Fig. 4, the tractor 12 comprises a high voltage controller 36 which is mounted inside the tractor 12 with a solar battery charger gateway 34 forming a control unit, a power distribution box 48, and a high voltage battery 50 as an accumulator. The tractor 12 is an electric driven vehicle for which purpose it has an electric engine 54 or an electric motor, respectively, that during operation propels the tractor 12. The electric engine 54 receives its energy from an inverter 52 which, in turn, receives its energy from the high voltage battery 50. In the present embodiment, the electric engine 54 is a three phase AC electric motor and the inverter 52 converts DC voltage supplied from the high voltage battery 50 to three phase AC voltage to be supplied to the electric engine 54. The electrical connections on the tractor 12, namely a second connector 20 and a fourth connector 32, are located on a flag bracket on a chassis next to the trailer 10 and its 7-way and trailer air connections. Respective cables are attached via a spring loaded cable so they do not interfere or become damaged during a trailer turning maneuver.

The goal of the invention is to produce as much usable energy as possible to provide propulsion by the tractor 12, using the electric engine 54, when the tractor 12 is moving as well as supply comfort loads, such as an electric air conditioner, when the tractor 12 is stationary. As a solar panel's peak power output, that is current multiplied by voltage, is a function of available sun light, it is optimal to have a maximum power point tracker (MPPT) in order to find the solar panel output voltage that would maximize the power output of the system. As the high voltage battery 50 presently requires a voltage over 360 V to charge, the solar system includes the solar battery charger 16 providing DC/DC-conversion. In this regard, the solar battery charger 16 provides an interface between the solar panels 42 and the high voltage battery 50.

Due to electrical requirements of the solar battery charger 16 in the present embodiment, the solar panels 42 are required to be wired in five parallel strings of three series panels 42 with one time use fuses 46 between each panel as shown in Fig. 4. The junction box 44 is required to electrically combine the solar panels 42 to be fed into the solar battery charger 16. The junction box 44 contains five manual reset circuit breakers 64 rated in this embodiment at 30 A as an added safety measure as well as a method to easily disconnect each solar string.

As can be further derived from Fig. 4, each panel's output voltage is approximately 33 V, therefore, each string of panel's outputs approximately 100 V. Each string is capable of up to 10 A in this embodiment, which means the rated power of the solar system is about 5000W. The national renewable energy laboratory testing procedure of solar panel power output uses a short pulse of 1000 W/m2 of solar equivalent light, which causes no heating of the solar panels 42 which is unrealistic in a real world scenario. Therefore, the actual maximum power output of the system will be closer to 4 kW.

Between the solar battery charger 16 and the high voltage battery 50 is a power distribution box 48 which is responsible for opening and closing the high voltage circuit from the solar system to the battery 50. The power distribution box 48 monitors the state of the connectors 18, 20 and the fuses 46 within and reports the status to the high voltage controller 36. The high voltage controller 36 is responsible for determining if the high voltage battery 50 is able to support current from the solar system of the trailer 10 and how much and reports this value to the solar battery charger gateway 34. The solar battery charger gateway 34 is responsible for monitoring the status of the tractor 12 in regard to the solar system of the trailer 10 and determines if it is safe to operate the solar system of the trailer 10. In addition, it routes control messages between the high voltage controller 36 and the solar battery charger gateway 34. The system is in this embodiment enabled once the solar battery charger gateway 34 receives 12 V between a trailer interlock input and ground which guarantees that all connections required for the system to function are properly connected.

The system will activate after air is supplied to the trailer 10, as read by an air switch inserted into the trailer primary air circuit on the tractor 12, as a signal that the trailer 10 is connected and the tractor 12 is ready to be operated. Conversely, removing 12 Von the air switch signal informs the system that the driver intends to decouple the trailer 10 from the tractor 12. Therefore, the system stops power production and discharges the high voltage system in preparation for the trailer 10 to be disconnected. The high voltage controller 36 monitors the battery state of charge signal in order to determine if the system is able to store additional charge. If the high voltage battery 50 is fully charged, the high voltage controller 36 sends a signal to deactivate the power production of the solar system of the trailer 10. The control logic is simple because the solar system does not provide sufficient power to charge the high voltage battery 50 quickly. For example, in this embodiment, it takes about five hours to charge the high voltage battery 50 completely when the solar system of the trailer 10 is outputting 50 % power while the electric engine 54 can charge the system in around 30 seconds.

In this regard, Fig. 4 shows a first connector 18 which is connected with the solar battery charger 16 and is provided with two power contacts 22, 24. Respectively, the tractor 12 has a second connector 20 being provided with two contacts 26, 28 which connect to the contacts 22, 24 of the first connector 18 in the connected status. Contacts 22, 26 provide the ground to relay 60 shown in Fig. 5, and an input to the SBC gateway 34 that tells the system that the trailer connections are connected. Contacts 24 and 28 are positive and negative high voltage connections.

Moreover, Fig. 4 also shows a third connector 30 for a communication line of the trailer 10 to be connected with a fourth connector 32 of the tractor 12 which, in turn, is connected with the solar battery charger gateway 34.

The system of the invention contains a solar disconnect switch 60 located in a main switch panel on the vehicle dashboard (not shown) that is used if the user does not want to have solar power from the trailer 10 at a given time or if the user wishes to reset the system. The solar disconnect switch 60 is primarily used for system debugging.

When the system of the invention is inactive, the high voltage line can be completely discharged in order to prevent someone from electrocuting themselves by touching one of the high voltage wires. To enable the high voltage circuit, the solar battery charger 16 receives a hard wired input signal via a communication link provided by the third and the fourth connectors 30. 32. The absence of that hardwired input activates the discharge circuit which grounds the high voltage line through a resistor in the SBC 16. The discharge circuit of the SBC 16 is active when the relay 60 of Fig. 5 is open. The relay 60 is open if any trailer connector is not connected or the SBC gateway 34 is not requesting the SBC 16 to disable the discharge circuit. If the system of the invention is active and any connector is disconnected the relay 60 will open which then activates the discharge circuit.

Due to the mechanical nature of the physically combined first and second connectors 18, the high voltage wires cannot be removed until the ground connector of the first and second connectors 18, 20 is removed. This provides the functionality that if the first to fourth connectors are removed while the system is active, the high voltage is immediately discharged creating a safe system. The solar battery charger 16 is designed to discharge the high voltage line once the input is removed within five seconds. Since the ground connector must be removed before the high voltage connector can be removed, the system is deemed safe. In addition, the ground connector requires a single stage action, e.g. pitch a lever lock and pull in order to remove it, whereas the high voltage connector requires two actions to remove it, e.g. unlock a slide lock and then pitch a lever lock and pull. Once the solar battery charger gateway 34 sees that the third connector 30 or the ground connector has been removed, it signals to the high voltage controller 36 to open the power distribution box 48 contactors. In addition, touchless connections were chosen for the connectors 18, 20. Touchless refers to the fact that a human finger cannot touch a terminal of the connectors 18, 20 directly. That a bare finger is unable to touch a high voltage wire warrants touchless connectors, e.g. the power contacts 22 to 28.

In addition to hardwired connections, if the high voltage controller 36 loses communication with the solar battery charger 16 mounted in the trailer 10, the high voltage controller 36 will request the power distribution box 48 to open its contactors for the solar system.

When the solar battery charger 16 loses communication with the high voltage controller 36, the solar battery charger 16 will deactivate power production of the system. As long as the wiring connectors are not compromised, the solar battery charger 16 will not discharge the high voltage wires. This is acceptable since the connections are guaranteed to be intact as described earlier.

The solar battery charger 16 continuously monitors further the insulation between the solar panels 42 and a trailer frame of the trailer 10. The solar batter charger 16 is adapted to shut down the system and report an error code if the resistance between the metal of the trailer 10 and the solar panels 42 reaches a dangerous level. This provides the user with information that the system needs to be serviced by a professional. This provides an additional layer of safety as the high voltage system integrity of the vehicle is monitored by the high voltage battery 50, but the solar system monitors the integrity of the charging system (Fig. 6). Fig. 7 shows a sectional view of the first and the second connectors 18, with regard to their respective power contacts 22 to 28.

An additional use of the solar trailer system is to feed power into the electrical grid while the trailer is not connected to a tractor. As trailers require time to be loaded and unloaded as well as potentially sit in a yard while not being used, it would be a large benefit to allow the solar panels 42 on the trailer 10 to be generating power when not connected to a vehicle.

Therefore, it is possible that the building or connection point provides the same interface to control the solar trailer the system can feed the DC high voltage power into an AC inverter which can be fed into the power grid. This assumes that the CAN and hardwired input signals required to safely operate a vehicle with the solar trailer are present in the charging infrastructure. In addition, as the AC inverter is not useful for the solar trailer/tractor combination, the AC inverter should be present at the charging point and not in the trailer as it would become a freight efficiency penalty.

While the use case is different, the method of operation can be identical as described above. If the connectors that are used to interface between the tractor and the trailer of the tractor are present at the charging point and the charging point has a gateway that gathers voltage and power requirements of the power grid, it can translate them to CAN messages that the SBC understands. This allows the solar trailer to charge the AC power grid and increases the duration which the solar panels mounted on the trailer are in operation.

If desired, the different functions and embodiments discussed herein may be performed in a different or a deviating order and/or currently with each other in various ways.

Furthermore, if desired, one or more of the above-described functions and/or embodiments may be optional or may be combined, preferably in an arbitrary manner.

Although various aspects of the invention are set out in the independent claim, other aspects of the invention comprise other combinations of the features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

It is also observed herein that, while the above describes exemplary embodiments of the invention, this description should not be regarded as limiting the scope. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

List of reference signs Trailer 12 Tractor 14 Solar generator 16 Solar battery charger 18 First connector Second connector 22 Power contact 24 Power contact 26 Power contact 28 Power contact Third connector 32 Fourth connector 34 Solar battery charger gateway 36 High voltage controller 38 Fifth connector Sixth connector 42 Solar panel 44 Junction box 46 Fuse 48 Power distribution box High voltage battery 52 Inverter 54 Electric engine 56 Roof 58 Rubber bumper Solar disconnect switch 62 Discharge circuit disable 64 Fuse

Claims

Claims A trailer (10) adapted to be coupled with a tractor (12), the trailer having a solar generator (14), an energy converter (16) connected with the solar generator (14), and a first electric connector (18) electrically connected with the energy converter (16) and adapted to be coupled with a respective second electric connector (20) of the tractor (12), wherein the first and the second electric connectors (18, 20) each have at least two respective power contacts (22, 24, 26, 28) in order to allow energy transfer from the trailer (10) to the tractor (12) in a connected status, wherein the energy converter (16) is adapted to convert electric energy supplied from the solar generator (14) and to make the converted electric energy available at the at least two power contacts (22, 24) of the tirst electric connector (18) by providing an electric voltage between the at least two power contacts (22, 24) of the first connector (18), characterized in that the energy converter (16) is adapted to detect the connected status and to provide the electric voltage in the connected status only.
2. The trailer according to claim 1, characterized in that the energy converter (16) is connected with a third connector (30) adapted to be coupled with a respective fourth connector (32) of the tractor (12) and to establish a communication link with a control unit (34) of the tractor (12) in a connected status, wherein the energy converter (16) is adapted to detect, weather the communication link is active, and to provide the electric voltage only it the communication link is active.
3. The trailer according to claim 1 or 2, characterized in that the energy converter (16) is adapted to detect a defect of an electric insulation and to provide the electric voltage only if the electric insulation has no defect.
4. The trailer according to any one of claims 1 to 3, characterized in that the energy converter (16) is adapted to provide the electric voltage in dependence on a control signal received from the control unit (34) of the tractor (12) via the communication link.
5. The trailer according to any one of claims 1 to 4, characterized in that the control unit (34) of the tractor (12) is adapted to detect an air supply and to provide the electric voltage only if the air supply is active.
6. The trailer according to any one of claims 1 to 5, characterized by a fifth electric connector (38) being adapted to be connected with a sixth electric connector (40) of the tractor (12) in order to establish an independent ground connection in the connected status.