Electric vehicle with photovoltaic cells and with a circuit arrangement for distributing energy

Abstract

The invention relates to an electric vehicle with photovoltaic cells (2) and with a circuit arrangement (4) for distributing energy, wherein the photovoltaic cells (2) are arranged on the body (3) of the electric vehicle (1), wherein the electric vehicle (1) comprises a high volt battery (5) and a low volt battery (6), wherein the circuit arrangement (4) comprises a high volt circuit (7) connected to the high volt battery (5), a low volt circuit (8) connected to the low volt battery (6) and at least one PV circuit (9) connected to at least one of the photovoltaic cells (2). It is proposed that the circuit arrangement (4) comprises an intermediate circuit (10), that the low volt circuit (8) is connected to the intermediate circuit (10) via a LV converter arrangement (11), that the high volt circuit (7) is connected to the intermediate circuit (10) via a HV converter arrangement (12) and that the at least one PV circuit (9) is connected to the intermediate circuit (10) via a PV converter arrangement (13).

Description

[0001] Electric vehicle with photovoltaic cells and with a circuit arrangement for distributing energy

[0002] The present invention relates to an electric vehicle with photovoltaic cells and with a circuit arrangement for distributing energy according to the general part of claim 1 and to a method of controlling an electric vehicle according to claim 14.

[0003] The present focus lies on self-charging electric vehicles equipped with photovoltaic cells. These vehicles are able to obtain at least a part of the energy needed via the photovoltaic cells instead of traditional charging. The main advantage of using solar cells in an electric vehicle is to extend the range of the vehicle by adding extra power to the battery. Solar cells can also help to reduce the environmental impact of the vehicle by using a clean, renewable energy source.

[0004] Many known automobiles with combustion engines have a low volt (LV) circuit, often operating at around 12V, for providing power to several electrical loads like the entertainment system. Electric vehicles often have an additional high volt (HV) circuit, primarily for powering the electric drive. Electric vehicles with photovoltaic cells can have one or more additional photovoltaic (PV) circuits. The operating voltage level of the PV circuit may vary depending on how much energy the photovoltaic cells are providing. A maximum power point tracking (MPPT) solar charge controller may be used to define the operating voltage level of the PV circuit. The electric vehicle may have a high volt battery and a low volt battery for efficiency reasons.

[0005] The photovoltaic cells may be used to charge either one of the batteries during different use cases. One important use case for an electric vehicle with photovoltaic cells is charging at least one battery while the electric vehicle is parked at a location exposed to the sun without the user currently using the electric vehicle.

[0006] Charging the high volt battery is often the main target of the photovoltaic cells as the high volt battery may be the main energy storage of the electric vehicle. Converter arrangements are used to convert between different voltage levels. However, boosting the operating voltage of the photovoltaic cells up to the voltage level of the high volt battery and providing necessary control and safety functions at the same time consumes some of the energy generated. In particular during times with low sun intensity the drain is relevant.

[0007] It is a challenge to improve on the known prior art to provide a more energy efficient electric vehicle.

[0008] The invention is based on the problem of improving the known electric vehicles such that a further optimization regarding the named challenge is reached.

[0009] The above-noted object is solved by the features of the characterizing part of claim 1.

[0010] The main realization of the present invention is that by providing an intermediate circuit between the PV circuit, the low volt circuit and the high volt circuit, a number of advantages can be achieved. It becomes possible to regulate the voltage of the intermediate circuit, in particular depending on the use case of the electric vehicle, to optimize the operating points of converter arrangements. It also becomes possible to put some parts of the electric vehicle into an inactive state and for example charge only the low volt battery during periods of time with low sun intensity. Generally, the flexibility of designing and using the circuits of the electric vehicle increases.

[0011] Proposed is an electric vehicle with photovoltaic cells and with a circuit arrangement for distributing energy, wherein the photovoltaic cells are arranged on the body of the electric vehicle, wherein the electric vehicle comprises a high volt battery and a low volt battery, wherein the circuit arrangement comprises a high volt circuit connected to the high volt battery, a low volt circuit connected to the low volt battery and at least one PV circuit connected to at least one of the photovoltaic cells.

[0012] Essential is that the circuit arrangement comprises an intermediate circuit, that the low volt circuit is connected to the intermediate circuit via a LV converter arrangement, that the high volt circuit is connected to the intermediate circuit via a HV converter arrangement and that the at least one PV circuit is connected to the intermediate circuit via a PV converter arrangement. According to one embodiment it is proposed that the LV converter arrangement comprises a, in particular bidirectional, DC-DC converter for converting a voltage of the intermediate circuit into a voltage of the low volt circuit and / or the voltage of the low volt circuit into the voltage of the intermediate circuit, and / or, that the HV converter arrangement comprises a, in particular bidirectional, DC-DC converter for converting a voltage of the intermediate circuit into a voltage of the high volt circuit and / or the voltage of the high volt circuit into the voltage of the intermediate circuit, and / or, that the PV converter arrangement comprises a, in particular bidirectional, DC-DC converter for converting a voltage of the intermediate circuit into a voltage of the PV circuit and / or the voltage of the PV circuit into the voltage of the intermediate circuit.

[0013] By using bidirectional DC-DC converters the flexibility of the proposed solution can be increased. It becomes possible to flexibly move power between the batteries. It may also be useful to be able to send current through the photovoltaic cells for diagnostic purposes.

[0014] According to one embodiment it is proposed that the PV converter arrangement comprises a solar charge controller for controlling the energy generation of at least one photovoltaic cell of the PV circuit, preferably, that the solar charge controller is an MPPT solar charge controller, and / or, that the solar charge controller controls the DC-DC converter of the PV converter arrangement.

[0015] According to one embodiment it is proposed that the circuit arrangement comprises a control unit for controlling at least parts of the circuit arrangement, in particular for controlling at least one of the converter arrangements, preferably, that during use of the vehicle the control unit controls the circuit arrangement such that the high volt circuit, the low volt circuit and the intermediate circuit have, at least sometimes, different voltages, preferably such that the high volt circuit, the low volt circuit, the intermediate circuit and the PV circuit have, at least sometimes, different voltages.

[0016] By providing different voltages for the circuits the converter arrangements may be used in optimized working points, increasing the overall efficiency. According to one embodiment it is proposed that during a charging of the low volt battery via the photovoltaic cells, in particular in a situation of use of the electric vehicle in which an electric drive of the electric vehicle is not active, preferably in a situation in which the electric vehicle is not in use by a user, the control unit controls the HV converter arrangement to be in an inactive state, and / or, that during a charging of the high volt battery via the photovoltaic cells, in particular in a situation of use of the electric vehicle in which an electric drive of the electric vehicle is not active, preferably in a situation in which the electric vehicle is not in use by a user, the control unit controls the LV converter arrangement to be in an inactive state.

[0017] By having one of the converter arrangements in an inactive state when the other battery is charged, the overall energy consumption can be reduced.

[0018] According to one embodiment it is proposed that the control unit controls one of the HV converter arrangement and the LV converter arrangement to be in the active state and one to be in the inactive state in a situation of use of the electric vehicle in which an electric drive of the electric vehicle is not active, preferably in a situation in which the electric vehicle is not in use by a user, depending on a state of charge of the high volt battery and / or a state of charge of the low volt battery and / or on a power generated by the photovoltaic cells to charge either the high volt battery or the low volt battery, preferably, that the control unit balances the charge states of the high volt battery and the low volt battery by selectively charging one of the batteries from the photovoltaic cells and / or during use of the electric drive.

[0019] The circuit arrangement of the proposed electric vehicle allows selectively charging the batteries and balancing the charge between the batteries, in particular such that the low volt battery can be charged in situations where only low intensity sunlight is available and charging the high volt battery would be inefficient.

[0020] According to one embodiment it is proposed that the control unit controls at least one of the converter arrangements to vary the voltage of the intermediate circuit, in particular depending on a situation of use of the electric vehicle and / or depending on a state of charge of the high volt battery, preferably, that a ratio between the voltage of the high volt circuit and the intermediate circuit is controlled to be constant by the control unit, in particular by keeping a duty cycle of a PWM of a DC-DC converter of the HV converter arrangement constant.

[0021] Adapting the voltage allows optimizing the working points of the converter arrangements depending on the situation of use. It is also possible to optimize the voltage level of the intermediate circuit to match an optimized working point of the combination of the PV converter arrangement and one of the other converter arrangements if the third converter arrangement is inactive.

[0022] According to one embodiment it is proposed that the control unit sets the voltage of the intermediate circuit to a first level when the LV converter arrangement is in the inactive state and to a second level, different from the first level, when the HV converter arrangement is in the inactive state, preferably, that the control unit sets the voltage of the intermediate circuit to a third level, different from the first and the second level, when the LV converter arrangement and the HV converter arrangement are in an active state, or, that the control unit sets the voltage of the intermediate circuit to the first level if the LV converter arrangement and the HV converter arrangement are in an active state.

[0023] The intermediate circuit voltage may be optimized to match the HV converter arrangement in most use cases.

[0024] According to one embodiment it is proposed that the control unit actively transfers energy from the low volt battery to the high volt battery when the electric drive is in use to allow for charging of the low volt battery via the photovoltaic cells when the electric drive is not in use, preferably, that the control unit controls the state of charge of the low volt battery to reach a state of charge below a predefined state of charge during use of the electric drive, more preferably, that the predefined state of charge is below 70%, preferably below 50%.

[0025] By having a lower state of charge for the low volt battery the electric vehicle is prepared for situations with low sunlight intensity and can then still charge efficiently. This simple measure increases the overall yield of the photovoltaic cells.

[0026] According to one embodiment it is proposed that the circuit arrangement comprises multiple PV circuits, preferably, that each of the PV circuits is connected to the intermediate circuit via a PV converter arrangement, more preferably, that each of the PV converter arrangements comprises a DC-DC converter and preferably a, in particular MPPT, solar charge controller controlling the DC-DC converter, more preferably, that the DC-DC converters of the PV converter arrangements are coordinated to provide the intermediate voltage.

[0027] If multiple PV circuits are provided, they may each be connected to the intermediate circuit separately.

[0028] According to one embodiment it is proposed that at least one PV circuit comprises two strings of photovoltaic cells and at least one PV circuit comprises only one string of photovoltaic cells.

[0029] By combining strings of photovoltaic cells into a circuit, less converter arrangements are needed.

[0030] According to one embodiment it is proposed that the voltage of the intermediate circuit is, at least sometimes higher than and / or equal to and / or lower than the voltage of the low volt circuit.

[0031] According to one embodiment it is proposed that the control unit sometimes controls the voltage of the intermediate circuit to be the voltage of the low volt circuit, preferably, that the control unit then controls the LV converter arrangement to be in the inactive state and to connect the intermediate circuit and the low volt circuit by bypassing the DC-DC converter of the LV converter arrangement.

[0032] Bypassing the LV converter arrangement makes for a further gain in efficiency.

[0033] Another teaching which is of equal importance relates to a method of controlling a proposed electric vehicle, in particular via the control unit.

[0034] All explanations given with regard to the electric vehicle are fully applicable. In particular, all method steps explained for the control unit may be steps of the proposed method and anything the electric vehicle is configured to do may be done as part of the proposed method. In the following, embodiments of the invention are explained with respect to the drawing. The drawing shows in

[0035] Fig. 1 , an electric vehicle with photovoltaic cells and

[0036] Fig. 2, the circuit arrangement and connected components.

[0037] Fig. 1 shows an electric vehicle 1 with photovoltaic cells 2 arranged on the body 3 of the vehicle as a preferred vehicle. The photovoltaic cells 2 may be integrated into the body 3 of the vehicle or secured, for example glued, on the body 3 of the vehicle. Here and preferably, the vehicle is an automobile. However, the vehicle may equally be another vehicle, like a bus. The electric vehicle 1 is propelled by an electric drive. Preferably, the vehicle is a land-based electric vehicle 1 .

[0038] Here and preferably, during sunshine batteries 5, 6 of the vehicle are charged by the photovoltaic cells 2. Depending on the orientation of the sun towards the vehicle, different photovoltaic groups may generate different amounts of energy.

[0039] Proposed is an electric vehicle 1 with photovoltaic cells 2 and with a circuit arrangement 4 for distributing energy. The circuit arrangement 4 may distribute energy to all the electrical loads of the vehicle as is generally known.

[0040] The photovoltaic cells 2 are arranged on the body 3 of the electric vehicle 1 . The electric vehicle 1 further comprises a high volt battery 5 and a low volt battery 6. The low volt battery 6 may be used mainly to easily power usual loads of the electric vehicle 1 like an entertainment system. The low volt battery 6 may have a nominal voltage of 12V or 24V for example. The high volt battery 5 may be used mainly to power the electric drive of the electric vehicle 1 and receive charging through a charge cable, possibly at very high currents for quick charging. The high volt battery 5 may have a voltage of at least 100V, for example 408V or 800V.

[0041] The circuit arrangement 4 comprises a high volt circuit 7 connected to the high volt battery 5, a low volt circuit 8 connected to the low volt battery 6 and at least one PV circuit 9 connected to at least one of the photovoltaic cells 2. Fig. 2 shows the respective circuits, the batteries 5, 6 and other components which will be explained.

[0042] It should be understood that "high" and "low" are relative terms to differentiate the batteries 5, 6 and circuits, not absolute terms. The high voltage is at least higher than the low voltage and any usual variations of the low voltage. The high voltage is preferably at least twice, more preferably at least five times, more preferably at least ten times as high as the low voltage.

[0043] Essential is that the circuit arrangement 4 comprises an intermediate circuit 10, that the low volt circuit 8 is connected to the intermediate circuit 10 via a LV converter arrangement 11 , that the high volt circuit 7 is connected to the intermediate circuit 10 via a HV converter arrangement 12 and that the at least one PV circuit 9 is connected to the intermediate circuit 10 via a PV converter arrangement 13.

[0044] The initialisms LV, HV and PV in front of terms are only used as identifiers for better identification of the different components.

[0045] A circuit has a nominal voltage, which may be changeable as will be explained. The circuit may have electrical loads connected between the potential of the circuit and the ground potential. Here and preferably, all circuits have the same ground potential. The converter arrangements between the circuits convert the different voltages of the circuits into each other. The intermediate circuit 10 may be physically rather small and just connect the different converter arrangements as it preferably does not have any electrical loads connected to it. It may for example be a bus connecting DC-DC converters 14 of the converter arrangements.

[0046] The electric vehicle 1 is here and preferably configured to execute the method steps in the following descriptions of use cases.

[0047] The LV converter arrangement 11 may comprises a, in particular bidirectional, DC-DC converter 14 for converting a voltage of the intermediate circuit 10 into a voltage of the low volt circuit 8 and / or the voltage of the low volt circuit 8 into the voltage of the intermediate circuit 10. The voltage of the low volt circuit 8 is here and preferably the voltage of the low volt battery 6. Additionally or alternatively, the HV converter arrangement 12 may comprise a, in particular bidirectional, DC-DC converter 14 for converting a voltage of the intermediate circuit 10 into a voltage of the high volt circuit 7 and / or the voltage of the high volt circuit 7 into the voltage of the intermediate circuit 10. The voltage of the high volt circuit 7 is here and preferably the voltage of the high volt battery 5.

[0048] Also, the PV converter arrangement 13 may comprise a, in particular bidirectional, DC-DC converter 14 for converting a voltage of the intermediate circuit 10 into a voltage of the PV circuit 9 and / or the voltage of the PV circuit 9 into the voltage of the intermediate circuit 10. Here and preferably, the voltage of the intermediate circuit 10 is, at least sometimes, preferably always, greater than the voltage of the PV circuit 9 or circuits. It should be understood that relations between voltages are always the nominal voltages and if one voltage is greater / smaller than another voltage, the difference is more than usual fluctuations and is specified, meaning it exists on purpose. The differences may be at least 10%, preferably at least 20%, more preferably at least 30% of the smaller voltage. The differences may also be at least 3V, preferably at least 5V.

[0049] Fig. 2 shows all three named DC-DC converters 14. It further shows that other PV circuits 9 with DC-DC converters 14 may be present.

[0050] It is preferably the case that the PV converter arrangement 13 comprises a solar charge controller 15 for controlling the energy generation of at least one photovoltaic cell 2 of the PV circuit 9, preferably, that the solar charge controller 15 is an MPPT solar charge controller 15, and / or, that the solar charge controller 15 controls the DC-DC converter 14 of the PV converter arrangement 13. The PV circuit 9 and / or the PV circuits 9 may comprise, in particular each, a string of photovoltaic cells 2. The solar charge controller 15 may control the whole string. The electric vehicle 1 may for example have at least one string of photovoltaic cells 2 on one side and / or another one the other side and / or one on the roof and / or one on the front engine hood or front trunk hood if the engine is at the back. Here and preferably, the circuit arrangement 4 comprises a control unit 16 for controlling at least parts of the circuit arrangement 4, in particular for controlling at least one of the converter arrangements.

[0051] Here and preferably, at least two control units 16 control parts of the circuit arrangement 4 and form the control unit 16. One of them may be an MPPT central control unit (MCU) 17 shown in Fig. 2, the other one may be a general vehicle control unit 18. All functions described for the control unit 16 may be performed by one control unit 16 or multiple control units 16. Generally, multiple control units 16 may form one control unit 16. The MCU 17 may also be the only control unit 16 controlling the circuit arrangement 4 in an alternative.

[0052] Here and preferably, the MCU 17 controls the solar charge controller 15 or solar charge controllers 15, in particular the energy supply of the solar charge controller 15 or solar charge controllers 15. The MCU 17 may be able to cut the power supply of the solar charge controller 15 or solar charge controllers 15.

[0053] The intermediate circuit 10 may be housed, in particular partially, inside a housing of the MCU 17. The MCU 17 may be located in a motor compartment of the electric vehicle 1 . The or some converter arrangements may be placed inside the MCU 17 or may be connected to the MCU 17. The MCU 17 may be connected to a low volt bus of the low volt circuit 8 and / or to a high volt bus of the high volt circuit 7. During a use of the electric vehicle 1 in which the electric drive is used for driving, the MCU 17 may be operated via the low volt circuit 8. In other use cases, the MCU 17 may feed current into the low volt circuit 8 as described. The MCU 17 may be connected via a bus, in particular CAN bus 19, to the vehicle control unit 18.

[0054] Preferably, during use of the vehicle the control unit 16 controls the circuit arrangement 4 such that the high volt circuit 7, the low volt circuit 8 and the intermediate circuit 10 have, at least sometimes, different voltages. It may be the case that the intermediate voltage is mainly set by the PV converter arrangement 13 or PV converter arrangements 13 and therefore the MCU 17 may control the voltage of the intermediate circuit 10. Preferably, the control unit 16 controls the circuit arrangement 4 such that the high volt circuit 7, the low volt circuit 8, the intermediate circuit 10 and the PV circuit 9 have, at least sometimes, different voltages. The PV converter arrangement 13 and / or the LV converter arrangement 11 may be controlled by the vehicle control unit 18, in particular via a CAN bus 19 connection. All explanations given with regard to a converter arrangement may apply to the DC-DC converter 14 of the arrangement.

[0055] The use of the vehicle includes normal use cases, including parking without a user when generating energy through the photovoltaic cells 2. The use does not include a completely inactive state of the electric vehicle 1 like parking at night with no user present and no relevant amount of artificial light reaching the photovoltaic cells 2.

[0056] Turning towards the control of the circuit arrangement 4, in particular the intermediate circuit 10, it may be the case that during a charging of the low volt battery 6 via the photovoltaic cells 2, in particular in a situation of use of the electric vehicle 1 in which an electric drive of the electric vehicle 1 is not active, preferably in a situation in which the electric vehicle 1 is not in use by a user, the control unit 16 controls the HV converter arrangement 12 to be in an inactive state. This use case may be a case in which the low volt battery 6 has a state of charge below its maximum state of charge and the energy generated by the photovoltaic cells 2 is relatively low. Then putting the HV converter arrangement 12 in an inactive state such that not power is passed through the DC-DC converter 14 of the HV converter arrangement 12 reduces the overall energy consumption and improves the charging efficiency.

[0057] Additionally or alternatively, during a charging of the high volt battery 5 via the photovoltaic cells 2, in particular in a situation of use of the electric vehicle 1 in which an electric drive of the electric vehicle 1 is not active, preferably in a situation in which the electric vehicle 1 is not in use by a user, the control unit 16 controls the LV converter arrangement 11 to be in an inactive state. Putting the LV converter arrangement 11 in the inactive state such that no power is passed from the photovoltaic cells 2 to the low volt battery 6 through the DC-DC converter 14 of the LV converter arrangement 11 allows setting the intermediate circuit 10 to any voltage that is efficient and saves energy for operating the LV converter arrangement 11 . This may be the case when the photovoltaic cells 2 are generating a high amount of energy.

[0058] Here and preferably, the control unit 16 controls the HV converter arrangement 12 and / or the LV converter arrangement 11 to be in the active or inactive state by controlling a power supply of the respective converter arrangement. In this case, the acting part of the control unit 16 may be the vehicle control unit 18.

[0059] A state in which the electric vehicle 1 is not in use by a user is in particular a parked state in which the electric vehicle 1 is central locked, in particular double locked, and no authorized user is in range of the electric vehicle 1 , for example no key or smartphone functioning as a key has a short range communicative connection, like Bluetooth, with the electric vehicle 1.

[0060] According to one embodiment it is proposed that the control unit 16 controls one of the HV converter arrangement 12 and the LV converter arrangement 11 to be in the active state and one to be in the inactive state in a situation of use of the electric vehicle 1 in which an electric drive of the electric vehicle 1 is not active, preferably in a situation in which the electric vehicle 1 is not in use by a user, depending on a state of charge of the high volt battery 5 and / or a state of charge of the low volt battery 6 and / or on a power generated by the photovoltaic cells 2 to charge either the high volt battery 5 or the low volt battery 6. It may be the case that depending on the state of charge of the low volt battery 6, in a case where the photovoltaic cells 2 are generating a low amount of energy, only the low volt battery 6 is charged, if its state of charge is low enough. In a case where the photovoltaic cells 2 generate a high amount of energy, depending on the states of charge of the batteries 5, 6, the high volt battery 5 and / or the low volt battery 6 may be charged.

[0061] Therefore, preferably, the control unit 16 balances the charge states of the high volt battery 5 and the low volt battery 6 by selectively charging one of the batteries 5, 6 from the photovoltaic cells 2 and / or during use of the electric drive.

[0062] As explained it may be the case that the control unit 16 controls at least one of the converter arrangements to vary the voltage of the intermediate circuit 10, in particular depending on a situation of use of the electric vehicle 1 and / or depending on a state of charge of the high volt battery 5. Specifically, it may be the case that a ratio between the voltage of the high volt circuit 7 and the intermediate circuit 10 is controlled to be constant by the control unit 16, in particular by keeping a duty cycle of a PWM of a DC-DC converter 14 of the HV converter arrangement 12 constant. The control unit 16 may control the ratio to be constant during varying voltages of the high volt battery 5. This embodiment has the advantage that the HV converter arrangement 12 may operate at a constant operating point and therefore at a maximum efficiency. The other converter arrangements may follow the intermediate circuits voltage. Keeping the ratio between the voltage of the high volt circuit 7 and the intermediate circuit 10 constant is also an easy way of feeding varying energy of the photovoltaic cells 2 into the high volt battery 5 during use cases of varying energy consumption and production (PV and recuperation) using low computational resources. The more energy is fed into the intermediate circuit 10, the more energy will be fed into the high volt battery 5 automatically.

[0063] The fixed ratio may be at least 2, preferably at least 4, more preferably at least 6, even more preferably at least 10. The fixed ratio may also be at most 30, preferably at most 20. For a nominal high volt battery voltage of 400V, a fixed ratio of 8 for example leaves the intermediate circuit voltage at around 50V, enabling a step up from the voltage of the photovoltaic cells and keeping the voltage low enough for safety reasons. For a nominal high volt battery voltage of 800V, the fixed ratio may be 16 for example, for the same reasons.

[0064] Here and preferably, the control unit 16 sets the voltage of the intermediate circuit 10 to a first level when the LV converter arrangement 11 is in the inactive state and to a second level, different from the first level, when the HV converter arrangement 12 is in the inactive state. The first level may be higher than the second level.

[0065] Preferably, the control unit 16 sets the voltage of the intermediate circuit 10 to a third level, different from the first and the second level, when the LV converter arrangement 11 and the HV converter arrangement 12 are in an active state Alternatively, the control unit 16 may set the voltage of the intermediate circuit 10 to the first level if the LV converter arrangement 11 and the HV converter arrangement 12 are in an active state. Both converter arrangements may in particular be active if the electric drive is active.

[0066] The first and / or second and / or third level, in particular all levels, of the voltage of the intermediate circuit 10 may be up to 60V for safety reasons, such that no galvanic isolation is needed between the PV circuit 9 and the intermediate circuit 10.

[0067] To balance the state of charge of the batteries 5, 6 and prepare for charging the batteries 5, 6 via the photovoltaic cells 2 in a parked state it may be the case that the control unit 16 actively transfers energy from the low volt battery 6 to the high volt battery 5 when the electric drive is in use to allow for charging of the low volt battery 6 via the photovoltaic cells 2 when the electric drive is not in use.

[0068] Preferably, the control unit 16 controls the state of charge of the low volt battery 6 to reach a state of charge below a predefined state of charge during use of the electric drive. The predefined state of charge may be below 70%, preferably below 50%, for example 30%.

[0069] As shown in Fig. 2 and according to one embodiment it is proposed that the circuit arrangement 4 comprises multiple PV circuits 9. Preferably, each of the PV circuits 9 is connected to the intermediate circuit 10 via a PV converter arrangement 13. Each of the PV converter arrangements 13 may comprise a DC-DC converter 14 and preferably a, in particular MPPT, solar charge controller 15 controlling the DC-DC converter 14. The DC-DC converters 14 of the PV converter arrangements 13 may be coordinated, in particular by the MCU 17, to provide the intermediate voltage.

[0070] All explanations given with regard to one PV converter arrangement 13 may be true for more than one or all PV converter arrangements 13. Here and preferably, the DC-DC controllers of the PV converter arrangements 13 operate as current sources with the voltage of the intermediate circuit 10 as output voltage.

[0071] According to one embodiment it is proposed that at least one PV circuit 9 comprises two strings of photovoltaic cells 2 and at least one PV circuit 9 comprises only one string of photovoltaic cells 2. In this way, less converter arrangements are necessary.

[0072] According to one embodiment it is proposed that the voltage of the intermediate circuit 10 is, at least sometimes higher than and / or equal to and / or lower than the voltage of the low volt circuit 8.

[0073] It may also be the case that the control unit 16 sometimes controls the voltage of the intermediate circuit 10 to be the voltage of the low volt circuit 8. Preferably, the control unit 16 then controls the LV converter arrangement 11 to be in the or another inactive state and to connect the intermediate circuit 10 and the low volt circuit 8 by bypassing the DC-DC converter 14 of the LV converter arrangement 11.

[0074] Another teaching which is of equal importance relates to a method of controlling a proposed electric vehicle 1 , in particular via the control unit 16.

[0075] All explanations given with regard to the electric vehicle 1 are fully applicable. The method may particularly be a method of operating the control unit 16 to control the circuit arrangement 4 in the described manner.

Claims

Claims1 . Electric vehicle with photovoltaic cells (2) and with a circuit arrangement (4) for distributing energy, wherein the photovoltaic cells (2) are arranged on the body (3) of the electric vehicle (1 ), wherein the electric vehicle (1 ) comprises a high volt battery (5) and a low volt battery (6), wherein the circuit arrangement (4) comprises a high volt circuit (7) connected to the high volt battery (5), a low volt circuit (8) connected to the low volt battery (6) and at least one PV circuit (9) connected to at least one of the photovoltaic cells (2), characterized in that the circuit arrangement (4) comprises an intermediate circuit (10), that the low volt circuit (8) is connected to the intermediate circuit (10) via a LV converter arrangement (11 ), that the high volt circuit (7) is connected to the intermediate circuit (10) via a HV converter arrangement (12) and that the at least one PV circuit (9) is connected to the intermediate circuit (10) via a PV converter arrangement (13).

2. Electric vehicle according to claim 1 , characterized in that the LV converter arrangement (11 ) comprises a, in particular bidirectional, DC-DC converter (14) for converting a voltage of the intermediate circuit (10) into a voltage of the low volt circuit (8) and / or the voltage of the low volt circuit (8) into the voltage of the intermediate circuit (10), and / or, that the HV converter arrangement (12) comprises a, in particular bidirectional, DC-DC converter (14) for converting a voltage of the intermediate circuit (10) into a voltage of the high volt circuit (7) and / or the voltage of the high volt circuit (7) into the voltage of the intermediate circuit (10), and / or, that the PV converter arrangement (13) comprises a, in particular bidirectional, DC-DC converter (14) for converting a voltage of the intermediate circuit (10) into a voltage of the PV circuit (9) and / or the voltage of the PV circuit (9) into the voltage of the intermediate circuit (10).

3. Electric vehicle according to claim 2, characterized in that the PV converter arrangement (13) comprises a solar charge controller (15) for controlling the energy generation of at least one photovoltaic cell (2) of the PV circuit (9), preferably, that the solar charge controller (15) is an MPPT solar charge controller (15),and / or, that the solar charge controller (15) controls the DC-DC converter (14) of the PV converter arrangement (13).

4. Electric vehicle according to one of the preceding claims, characterized in that the circuit arrangement (4) comprises a control unit (16) for controlling at least parts of the circuit arrangement (4), in particular for controlling at least one of the converter arrangements, preferably, that during use of the vehicle the control unit (16) controls the circuit arrangement (4) such that the high volt circuit (7), the low volt circuit (8) and the intermediate circuit (10) have, at least sometimes, different voltages, preferably such that the high volt circuit (7), the low volt circuit (8), the intermediate circuit (10) and the PV circuit (9) have, at least sometimes, different voltages.

5. Electric vehicle according to one of the preceding claims, characterized in that during a charging of the low volt battery (6) via the photovoltaic cells (2), in particular in a situation of use of the electric vehicle (1 ) in which an electric drive of the electric vehicle (1 ) is not active, preferably in a situation in which the electric vehicle (1 ) is not in use by a user, the control unit (16) controls the HV converter arrangement (12) to be in an inactive state, and / or, that during a charging of the high volt battery (5) via the photovoltaic cells (2), in particular in a situation of use of the electric vehicle (1 ) in which an electric drive of the electric vehicle (1 ) is not active, preferably in a situation in which the electric vehicle (1 ) is not in use by a user, the control unit (16) controls the LV converter arrangement (11 ) to be in an inactive state.

6. Electric vehicle according to claims 4 and 5, characterized in that the control unit (16) controls one of the HV converter arrangement (12) and the LV converter arrangement (11 ) to be in the active state and one to be in the inactive state in a situation of use of the electric vehicle (1 ) in which an electric drive of the electric vehicle (1 ) is not active, preferably in a situation in which the electric vehicle (1 ) is not in use by a user, depending on a state of charge of the high volt battery (5) and / or a state of charge of the low volt battery (6) and / or on a power generated by the photovoltaic cells (2) to charge either the high volt battery (5) or the low volt battery (6), preferably, that the control unit (16) balances the charge states of the high volt battery (5) and the low volt battery (6) by selectively charging oneof the batteries (5, 6) from the photovoltaic cells (2) and / or during use of the electric drive.

7. Electric vehicle according to one of claims 4 to 6, characterized in that the control unit (16) controls at least one of the converter arrangements to vary the voltage of the intermediate circuit (10), in particular depending on a situation of use of the electric vehicle (1 ) and / or depending on a state of charge of the high volt battery (5), preferably, that a ratio between the voltage of the high volt circuit (7) and the intermediate circuit (10) is controlled to be constant by the control unit (16), in particular by keeping a duty cycle of a PWM of a DC-DC converter (14) of the HV converter arrangement (12) constant.

8. Electric vehicle according to claim 7, characterized in that the control unit (16) sets the voltage of the intermediate circuit (10) to a first level when the LV converter arrangement (11 ) is in the inactive state and to a second level, different from the first level, when the HV converter arrangement (12) is in the inactive state, preferably, that the control unit (16) sets the voltage of the intermediate circuit (10) to a third level, different from the first and the second level, when the LV converter arrangement (11 ) and the HV converter arrangement (12) are in an active state, or, that the control unit (16) sets the voltage of the intermediate circuit (10) to the first level if the LV converter arrangement (11 ) and the HV converter arrangement (12) are in an active state.

9. Electric vehicle according to one of claims 4 to 8, characterized in that the control unit (16) actively transfers energy from the low volt battery (6) to the high volt battery (5) when the electric drive is in use to allow for charging of the low volt battery (6) via the photovoltaic cells (2) when the electric drive is not in use, preferably, that the control unit (16) controls the state of charge of the low volt battery (6) to reach a state of charge below a predefined state of charge during use of the electric drive, more preferably, that the predefined state of charge is below 70%, preferably below 50%.

10. Electric vehicle according to one of the preceding claims, characterized in that the circuit arrangement (4) comprises multiple PV circuits (9), preferably, that each of the PV circuits (9) is connected to the intermediate circuit (10) via a PV converter arrangement (13), more preferably, that each of the PV converterarrangements (13) comprises a DC-DC converter (14) and preferably a, in particular MPPT, solar charge controller (15) controlling the DC-DC converter (14), more preferably, that the DC-DC converters (14) of the PV converter arrangements (13) are coordinated to provide the intermediate voltage.

11. Electric vehicle according to claim 10, characterized in that at least one PV circuit (9) comprises two strings of photovoltaic cells (2) and at least one PV circuit (9) comprises only one string of photovoltaic cells (2).

12. Electric vehicle according to one of the preceding claims, characterized in that the voltage of the intermediate circuit (10) is, at least sometimes higher than and / or equal to and / or lower than the voltage of the low volt circuit (8).

13. Electric vehicle according to one claims 4 to 12, characterized in that the control unit (16) sometimes controls the voltage of the intermediate circuit (10) to be the voltage of the low volt circuit (8), preferably, that the control unit (16) then controls the LV converter arrangement (11 ) to be in the inactive state and to connect the intermediate circuit (10) and the low volt circuit (8) by bypassing the DC- DC converter (14) of the LV converter arrangement (11 ).

14. Method of controlling an electric vehicle (1 ) according to one of claims 1 to 13, in particular via the control unit (16).

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