ELECTRONIC CIRCUIT FOR A PHOTOVOLTAIC MODULE AND METHOD FOR CONNECTING A PHOTOVOLTAIC MODULE

Description

[0001] The present invention relates to an electronic circuit for a photovoltaic module, a photovoltaic system, a vehicle with a photovoltaic system, and a method for connecting a photovoltaic module to a photovoltaic string. The present invention further relates to an intelligent circuit for electric cars for disconnecting a vehicle-internal photovoltaic (PV) high-voltage string.

[0002] The field of vehicle-integrated photovoltaics (VIPV) is characterized by high dynamics. A wide variety of manufacturers now offer solutions. A distinction can be made between the passenger car and commercial vehicle sectors. Due to the limited space in passenger cars and applicable safety regulations, solutions with a maximum photovoltaic (PV) voltage of < 60 V (safety extra-low voltage) have prevailed. Compliance with the maximum voltage is achieved by connecting the PV modules or PV strings in parallel or by using a separate DC / DC converter input for each module. In the commercial vehicle sector, larger installable PV outputs can be realized due to the large usable roof area. Even for smaller trucks, an output in the single-digit kW range can be expected.To minimize cabling effort and cable cross-section, it is advisable to connect the PV modules in series, thus keeping the PV current low. However, in this case, the PV voltage exceeds the safety extra-low voltage.

[0003] During normal operation of the PV modules, the DC / DC converter, the high-voltage (HV) circuit, and the HV battery of a PV system, the insulation is monitored by an insulation monitor. However, if, for example, the HV circuit is interrupted in the event of an accident, thus disconnecting the battery, the insulation monitor no longer provides protection for the PV side. The potentially dangerous voltage of the series-connected PV modules (open-circuit voltage) remains present throughout the entire PV circuit. Even during the disconnection of the so-called service disconnect box, an undesirably high voltage remains in the PV circuit. A prior art electronic circuit for a photovoltaic module is disclosed in document US 2013 / 320778 A1.

[0004] To avoid the problem of high voltages in vehicle-integrated photovoltaics, series connection of PV modules and PV strings has been avoided to date, or at most, series connections within the scope of protective extra-low voltages are implemented. In the field of stationary photovoltaics, solutions exist that utilize a communication channel between a central DC / DC converter or inverter and the individual PV modules via power line communication (PLC).

[0005] Concepts for the simple and safe connection of PV modules in a PV string would be desirable.

[0006] An object of the present invention is therefore to provide an electronic circuit for a PV module, a photovoltaic assembly, a PV system, a vehicle with a PV system and a method for connecting a PV module, which make it possible to connect a PV module to a string with little expenditure on material and complexity.

[0007] This problem is solved by the subject matter of the independent patent claims and 15.

[0008] Advantageous further developments are defined in the dependent patent claims.

[0009] A core idea of ​​the present invention is the recognition that a reversal of the direction of current flow in the PV string can be used as an information basis or carrier to stimulate a decentralized electronic circuit to reconnect the PV module it manages or is connected to with the PV string. This enables a decentralized decision to be made regarding the separation of the PV module from the PV string in order to meet safety requirements, particularly with regard to protective extra-low voltage, in the event of unforeseen and / or foreseeable events, such as an accident or the like. This makes it possible to implement a series connection of PV modules that enables high voltages during normal operation but reduces the respective voltage when necessary, thus offering a high degree of safety.On the one hand, switching on by means of the changed current direction checks whether the PV string is intact and, on the other hand, makes it possible to do without a separate communication channel, so that switching on the respective PV module into the string is possible with low risk and, at the same time, with low complexity.

[0010] According to one embodiment, an electronic circuit for a PV module comprises PV terminals for coupling to the PV module and string terminals for coupling to a PV string. A current path runs between the PV terminals and the string terminals and is designed to conduct an electrical current generated in the PV module to the PV string in a first current flow direction. A disconnection device is arranged between at least one of the PV terminals and at least one of the string terminals and is designed to interrupt the current path in a first state along the first current flow direction and to close the current path in a second state along the first current flow direction.The electronic circuit comprises a control device which is designed to obtain current flow information about a current flow in at least a partial section of the current path along a second current flow direction opposite to the first current flow direction and to control the separation device from the first state to the second state based on the current flow information.

[0011] According to one embodiment, the isolation device is configured to comprise a semiconductor switch with a switchable current path and a body diode acting in parallel with the switchable current path. The isolation device is configured to conduct the current flow via the body diode along the second current flow direction in the first state of the isolation device. This enables a simple yet reliable implementation for detecting the current flow in the second current flow direction. A current flow through the switch part of the semiconductor switch can be prevented due to its activation, while the body diode, which is conductive along the second current flow direction, is correspondingly effective.

[0012] According to one embodiment, the isolation device comprises at least a first and a second semiconductor switch connected in series or parallel to one another, which does not preclude additional semiconductor switches. The serially connected semiconductor switches comprise conductive body diodes acting along the second current flow direction. A parallel connection of such switches can also be configured accordingly. The advantage of this is that these body diodes can be used without significant additional effort, and at the same time, semiconductor switches can be switched quickly and reliably.

[0013] According to one embodiment, the electronic circuit comprises a sensor device configured to detect a current flow along the second current flow direction; wherein the current flow information is based on the detected current flow. This is advantageous in that the current flow can be detected using simple means.

[0014] According to one embodiment, the sensor device is designed to detect a voltage drop across a body diode of a semiconductor switch of the isolation device, wherein the voltage drop is causally related to the current flow. This is advantageous in that a voltage can be detected using simple means. Even if a current intensity can be evaluated, embodiments can detect the current flow along the second direction simply from the presence of the voltage drop across the at least one body diode, so that the electronic circuit can use this information to connect the PV module.

[0015] According to one embodiment, the electronic circuit comprises a bypass diode coupled between the string terminals and configured to enable an electrical current flow in the string in the first state. Thus, in the first state, the string's current can be conducted via the bypass diode. The oppositely directed current along the second current flow direction is not conducted or suppressed by the bypass diode, so that the current flow, e.g., via the body diodes, along the second current flow direction can be easily detected.

[0016] According to one exemplary embodiment, the control device is configured to control the disconnection device from the second state to the first state based on a shutdown event. Shutdown events can include, for example, an open circuit, shading, and / or a string short circuit. According to one possible embodiment, the control device can be configured to recognize the shutdown event as a shutdown event caused in the PV module, the string, or the electronic circuit, i.e., a decentralized shutdown event. Decentralized shutdown is easily possible because, by means of the current flow along the second current flow direction, a centrally initiated connection can be triggered at least temporarily.

[0017] According to one embodiment, the control device is configured to control the disconnection device into the second state after the detected shutdown event, i.e., after a successful disconnection, depending on the current flow received through the string along the second current flow direction. This makes it possible to at least tentatively transition back to the second state, allowing the control device to check whether the shutdown event is still present or has been resolved, for example, after permanent shading.

[0018] According to one exemplary embodiment, the control device is designed to temporarily switch the disconnecting device to the first state in the event of a temporary drop in power of the PV module, for example during a prolonged shading situation, and to control it to the second state independently of the current flow received via the string along the second current flow direction, for example to check whether a temporary drop in power causing the shutdown has ended. This means that the impulse to switch to the second state received via the string and indicated by the current flow along the second direction does not have to be the only way to switch to the second state. Rather, a decentralized decision can also be made to switch to this state, at least temporarily, or to return, which offers advantages even during shorter periods of shading.

[0019] According to one embodiment, the electronic circuit is designed without a communication interface, which means that the change between the operating states can, in the broader sense, take place without communication or without explicit communication, for example by interpreting the current flow along the second current flow direction without having to transmit messages of a communication protocol, which enables simple control of the PV system.

[0020] According to one embodiment, the electronic circuit is designed to, in the second state of the separating device, at least one of a) Maximum Power Point Tracking (MPPT) for the PV module, b) disconnecting the PV module from the string when a short circuit is detected, c) disconnecting the PV module from the string when open circuit of the PV module is detected and d) disconnecting the PV module from the string when shading of the PV module is detected and / or reconnecting the PV module when the end of shading is detected to perform, that is, to perform one or more of these functions. This allows the implementation of additional functions in the electronic circuit, eliminating the need for additional components and thus providing an advantage.

[0021] According to one embodiment, a photovoltaic assembly includes a PV module and an electronic circuit described herein coupled to the PV module.

[0022] According to one embodiment, a PV system comprises a plurality of PV modules connected in series to form a string according to the embodiments described herein. Such PV systems make it possible to utilize high PV voltages while simultaneously avoiding them when a safe state of the PV system or PV plant is required by disconnecting the respective PV module from the string.

[0023] According to one embodiment, an electrical voltage converter coupled to the string is provided for this purpose, which is designed to maintain and convert an electrical circuit based on the current flow in the first current flow direction. Furthermore, a source for establishing the current flow in the second current flow direction is provided in the PV system. The voltage converter is designed to control the source in order to connect at least one PV module in the string. This means that, based on the control of the source by the voltage converter, the PV module can be caused by the electronic circuit arranged therein to recouple the PV module to the string.

[0024] According to one embodiment, the voltage converter comprises the source or provides a function of the source. This can be achieved, for example, by varying the input voltage at the voltage converter, which leads to a reversal of the current flow direction in the string, at least temporarily, thus providing the current flow along the second current flow direction. This function can be implemented using simple means and still enable reliable control of the PV system.

[0025] According to one embodiment, the source is configured to provide the current along the second current flow direction as a direct current. This is advantageous in that complex modulation and / or generation or conversion of an alternating voltage or an alternating current can be dispensed with.

[0026] According to one embodiment, the source has a current limiter and / or is designed to provide a constant current. This is advantageous in that the source does not need to know the string configuration in the PV system or the currently required voltage, as this can be adjusted automatically by the constant current.

[0027] According to one embodiment, a vehicle comprises a PV system described herein. Such a vehicle may, for example, be a passenger car or any other vehicle, but is preferably a truck that can provide a large area for PV modules.

[0028] According to one embodiment, a method for connecting a PV module in a PV string comprises applying a control current directed opposite to the first current direction to an electronic circuit. The electronic circuit is coupled between the PV module and the PV string and is in a first operating state in which a disconnection device disconnects a current path running through the PV module and in which a current supplied from the PV module to the string in a first current direction is prevented. The method further comprises controlling the disconnection device, based on the control current, into a second state in which the current flow along the first current direction is enabled in order to close the current path.

[0029] Preferred embodiments of the present invention are explained below with reference to the accompanying drawings, in which: Fig. 1 shows a schematic block diagram of an electronic circuit according to an embodiment; Fig. 2 shows a schematic block diagram of a PV module according to an embodiment; Fig. 3 shows a schematic block diagram of a PV system according to an embodiment; Fig. 4 shows a UI characteristic curve of a PV module when switched on according to an embodiment; Fig. 5 shows a UI characteristic curve of a PV module according to embodiments during MPP tracking; Fig. 6 shows a UI characteristic curve for explaining switching off due to short circuit and open circuit according to an embodiment; Fig. 7 shows an exemplary tabular representation of different states of an electronic circuit according to an embodiment; Fig. 8 shows a schematic side sectional view of a vehicle according to an embodiment; and Fig. 9 shows a schematic flow diagram of a method according to an embodiment.

[0030] Before exemplary embodiments of the present invention are explained in more detail below with reference to the drawings, it is pointed out that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to one another.

[0031] The embodiments described below are described in conjunction with numerous details. However, embodiments may also be implemented without these detailed features. Furthermore, for clarity, embodiments are described using block diagrams instead of detailed illustrations. Furthermore, details and / or features of individual embodiments may be readily combined with one another, unless explicitly described otherwise.

[0032] Fig. 1 shows a schematic block diagram of an electronic circuit 10 according to one embodiment. The electronic circuit is preferably designed for a photovoltaic (PV) module 12, which may, but is not necessarily, part of the electronic circuit 10.

[0033] The electronic circuit 10 comprises PV terminals 14 1 and 14 2 , which are configured for coupling to the PV module 12. The number of PV terminals 14 1 and 14 2 can be adapted to the design of the PV module 12 and can comprise at least 1, at least 2, at least 3, at least 4, or more terminals. The voltage U PV_in is preferably within the range of the protective extra-low voltage and is, for example, at most or less than 48 volts or at most or less than 60 volts, so that one or more PV modules 12 can also be coupled to one another.

[0034] The electronic circuit 10 further comprises string terminals 16 1 and 16 2 , preferably at least two in number, which are configured to be connected in combination with one or more electronic circuits or PV modules in a PV string. For example, a series connection of several PV modules can be provided in the PV string.

[0035] A current I PV , which is supplied by the PV module 12, can be conducted along a first current flow direction through a current path 22 along the first current flow direction 18. The first current flow direction 18 can result at least partially from the design of the PV module 12, for example with regard to a positive pole and / or a negative pole and a polarity of the PV module 12 relative to the circuit. In the current path 22, that is to say between at least one of the PV connections 14 1 , 14 2 and at least one of the string connections 16 1 , 16 2 , a disconnection device 24 is arranged, which is designed to interrupt the current path 22 in a first state along the first current flow direction 18 and to close the current path in a second state along the first current flow direction 18. The disconnection device can, for example, have at least one switch, a switch arrangement and / or optionally additional elements.Semiconductor switches with body diodes, which enable current conductivity opposite to the first current flow direction 18, are particularly preferred.

[0036] The separation device can be arranged in the positive path, as shown, or at least partially in the negative path. Alternatively to the arrangement shown, the controller (26) can also be arranged at least partially on the PV module side in order to use the electrical power generated there as an energy supply.

[0037] The electronic circuit 10 comprises a control device 26, which is designed to obtain current flow information about a current flow or a current flow direction in at least a partial section of the current path 22 along a second current flow direction 28 opposite to the first current flow direction 18. Based on the current flow information, i.e. that a current I control flows along the second current flow direction 28 through at least the partial section of the current path 22, the control device 26 is designed to control the disconnection device 24 from the first state to the second state, i.e., to connect the PV module 12 to the string, for example, by controlling a switch 32 of the disconnection arrangement 24 to a conductive state.The first current flow direction 18 can thus be directed from the PV module to the string, while the second current flow direction can be from the string to the PV module and, for example, via the body diodes. The switch 32 can be formed differently, for example, as a semiconductor switch, such as a mechanical switch or the like. A semiconductor switch can be formed, for example, as a MOSFET or an IGBT.

[0038] The current I control can, for example, flow via the control device 26 and / or via correspondingly configured elements of the isolating device 24. A current flowing via the isolating device 24 along the second current flow direction 28 can also be detected by the control device 26 without the control device 26 having to be part of the current path 22 for this purpose.

[0039] Fig. 2shows a schematic block diagram of a PV assembly 200 according to one embodiment. The PV assembly comprises the PV module 12 and an electronic circuit 20 coupled to the PV module 12. The electronic circuit 10 can easily be provided alternatively or in addition to the electronic circuit 20.

[0040] The electronic circuit 20 comprises a control device 34, which can have the functions of the control device 26. The control device 34 can have information about a series of voltages and / or currents in the electronic circuit 20 and, based thereon, control the isolating device 24. In the illustrated embodiment, the isolating device 24 comprises, by way of example, two semiconductor switches 36 1 and 36 2 connected in series with one another, which are designated S 1 and S 2 and whose body diodes 38 1 and 38 2 are rectified, i.e., they are electrically conductive along the second current flow direction 28. It should be noted, however, that any other arbitrary number of switches, i.e., at least one, at least two, at least three or more switches, can also be connected in series and / or parallel in the isolating device 24.

[0041] Alternatively or additionally, the use of semiconductor switches is a possible embodiment, but other types of switching elements than switch 32 of the isolating device 24, such as mechanical switches or relays, can also be used to interrupt the current path 22 in the first state. The arrangement of several elements connected in series and / or parallel to one another enables high reliability and / or high flexibility in component selection. For example, a first switch that is permanently conductive in a fault state can be compensated for by a second switch connected in series with it, which can still be brought into an open state.

[0042] The control current I control can flow along the current flow direction 28 even when the switches 36 1 and 36 2 are open or non-conductive via the body diodes 38 1 and 38 2. A different current path results from these body diodes 38 1 and 38 2 compared to the switches when compared to the current path 22 and, for example, a mechanical switch is considered in conjunction with a separately connected diode. If a semiconductor switch is used as switch 36 1 and / or 36 2, the current path 22 can also be fully utilized by the control current I control. Implementing the switch 32 as at least one MOSFET semiconductor switch or using multiple switches, at least one of which is formed as a MOSFET, may enable synergistic use of an intrinsic body diode 38 1 and / or 38 2 , but this does not preclude the connection of additional diodes.If the isolation device 24 comprises, for example, a different type of semiconductor switch, such as an IGBT, an effect comparable to that of the body diode 38 1 and / or 38 2 can be achieved by connecting an additional diode in parallel or antiparallel. Such a diode connection can also be implemented using a mechanical switch or relay. It should be noted that the isolation device 24 can have one or more switching elements of the same or different types.

[0043] Optionally, one or more of the following information sources can be arranged in the electronic circuit 20 to provide the control device 34 with additional information. For example, a sensor device 42 can be provided that detects an electrical voltage U PV_in provided by the PV module 12 and delivers a corresponding signal to the control device 34. Alternatively, the corresponding voltage can also be measured directly in the control device 34.

[0044] Alternatively or additionally, the electronic circuit 20 can have a sensor device 44 that is designed to detect a direction of current flow. For this purpose, the sensor device 44 can detect, measure, or record a voltage drop 43 1 and / or 43 2 across at least one of the body diodes 38 1 or 38 2 . In this case, the information obtained by measuring only one of the two voltage drops 43 1 or 43 2 or a subset of the at least two voltage drops of the at least two semiconductor switches can be sufficient. It should be noted that if only one switch is used, one voltage drop can be measured, and if more than two switches are used, a correspondingly higher number of drops or components can also be measured for the total voltage drop.Alternatively, the voltage drop 43 1 and 43 2 can be measured individually across each of the at least two series-connected switches, or a total voltage drop between points 45 1 and 45 2 can be measured.

[0045] The voltage drop 43 1 across the body diode 38 1 and / or the voltage drop 43 2 across the body diode 38 2 can be causally related to the current flow I Steuer along the second current flow direction 28. If, for example, the voltage drop 43 1 or 43 2 exceeds a predefined threshold value influenced by a respective threshold voltage of the respective body diode 38 1 or 38 2, this indicates a current flow along the second current flow direction. Analogously, a combinational threshold value is influenced by the combination of threshold voltages of the series-connected body diodes 38 1 and 38 2 when the measurement is performed via points 45 1 and 45 2. Even if a detailed evaluation with regard to current intensity or the like is not excluded, a binary decision in the sense of yes / no may be sufficient for assessing the presence of the control current I control.

[0046] The sensor device 44 can provide a signal 46 indicating information about the presence of the current flow I control. The information can be present when the signal 46 is provided or, for example, when the signal 46 is not provided or is provided with a changed characteristic such as amplitude or frequency. For example, switching off the signal 46 can provide information about whether the current I control has started, just as switching on the signal 46 can. The current flow information of the control device 34 can be based on the detected current flow. The signal 46 can, for example, be the detected voltage 43 1 and / or 43 2 itself or a signal derived therefrom.

[0047] Although the sensor device 44 is depicted as a separate element from the control device, which is coupled to the control device 34 at least for transmitting the signal 46 provided by the sensor device 44, the sensor device 44 can also form part of the control device 34 and, for example, be integrated into it. As a result, the signal 46 can, for example, be generated internally or be omitted entirely, and / or the control device 34 can directly detect the voltage drops 43 1 and / or 43 2 .

[0048] The electronic circuit 20 can optionally include additional elements. For example, a bypass diode designated D 1 can be coupled between the string terminals 16 1 and 16 2 , which is designed to enable an electrical current flow in the string in the first state in which the disconnection device 24 disconnects the current path 22, for example, to enable current flow to other PV modules connected in series.

[0049] This does not preclude the optional arrangement of at least one resistance element 52 and / or capacitor element 54. Alternatively or additionally, a sensor device 55 for measuring a voltage U PV_out may also be provided.

[0050] Optionally, a voltage source 56, designated Auxiliary / AUX Supply 56, may also be provided, which is designed to provide a supply voltage 58 from the voltage U PV_in generated by the PV module 12, for example 3.3 volts, or any other value adapted to the control device 34, in order to operate the control device 34. The electronic circuit may have a buffer or energy storage device that can provide an energy reserve for supplying the electronic circuit in the event that the PV module provides insufficient amounts of energy.

[0051] The electronic circuit 20 and / or the control device 34 can be operated with respect to a reference potential GND, which can be a local reference potential or an electrical ground, particularly during stationary operation. When the electronic circuit 20 is operated in a vehicle, for example, the local reference potential GND can be connected, for example, to the body and / or a potential of a vehicle battery. However, different electronic circuits in a string can also have different reference potentials from one another.

[0052] The control device 34 can obtain information about whether and / or at what level a current U PV_SM is being provided by the PV module 12 or is being conducted to the string. Alternatively or additionally, the control device 34 can obtain information about the level of the current I SM_Bypass flowing through the bypass diode 48. Alternatively or additionally, the voltage U PV_in applied across the PV module can also be known to the control device 34 and / or the direction of current flow can be determined via the sensor device 44.

[0053] This amount of information enables diverse control of the electronic circuit 20 in a PV system.

[0054] In other words, a possible developed solution described in exemplary embodiments comprises an electronic circuit having, as its central element, a switch, the disconnecting device 24, for disconnecting the PV module string. This switch(es) can be switched on or connected, or switched on or off or disconnected based on various measurable parameters, thus ensuring that in the event of an accident or with an intact HV circuit, the series connection of the PV modules is disconnected and the voltage in the PV circuit remains below the protective extra-low voltage.

[0055] The circuit includes an input to which a PV module 12 can be connected. A voltage supply fed from the PV module voltage can be provided, and one, two, or more series-connected switches with an isolating function and a bypass diode can be arranged between the input and output. Optionally, one or more of the following variables can be measured: input voltage, output voltage, PV current, and bypass current. The switch states can be determined from the measured values ​​using logic in the control device.

[0056] In other words, Fig. 2A schematic block diagram of a smart PV module as a circuit for communication-free connection and disconnection, i.e., one that does not require a communication bus or the like. This does not prevent the transmission of information in the broader sense, such as a stimulus for connection via the current I control. Alternatively or additionally, other states or commands can also be transmitted to the PV module. To trigger a disconnection on the PV module side, for example, the PV system can generate a short circuit or open circuit in the string to trigger the desired behavior, i.e., disconnection.

[0057] Fig. 3 shows a schematic block diagram of a PV system 300 according to an embodiment. In the PV system 300, a plurality of at least 2, at least 3, at least 5, at least 10 or more PV modules can be connected in series to form a string 62. The PV modules can, for example, be arranged in accordance with the Fig. 2be formed, wherein a larger number of PV modules can easily be coupled to an electronic circuit and / or the electronic circuit 10 can be coupled to one or more of the PV modules. The electronic circuit 20 of a respective PV assembly 200 1 to 200 n with n > 1 can disconnect the respective PV module 12 1 to 12 n from the string 62. Optionally, the PV system 300 can have a so-called service disconnect box 64, that is, a device for disconnecting the PV components or PV assemblies 200 from other components, such as a voltage converter 66, which can be designed, for example, as a DC / DC converter in order to operate a high-voltage (HV) battery 68, for example in the case of a grid connection, but can also be operated as a DC / AC converter or galvanically isolating converter. Alternatively or additionally, an insulation monitor 72 can be connected to the battery 68.This does not exclude additional elements, such as switches 74 1 and / or 74 2 or resistors / inductors 76.

[0058] In the PV system 300, the electrical voltage converter 66 can be configured to receive and convert an electrical voltage based on the current flow in the first current flow direction 18, which is designated, for example, as U PV . The PV system 300 includes a source 78 for applying the current flow in the second current flow direction 28, for example, the current I Steuer from Fig. 2The voltage converter 66 can be designed to control the source 78, for example by means of a control signal 82, in order to switch on at least one of the PV modules 200 1 to 200 n in the string 62. In this case, the current I control can, for example, be effective for all PV modules 200 1 to 200 n, which, however, only leads to a change in the sign of the voltage 43 1 or 43 2 or the voltage between 45 1 and 45 2 in PV modules 200 that are in the disconnected, first state. In contrast, no change in state is effected for active and switched-on PV modules that are in the second state.

[0059] A temporal duration of the current I control along the second current flow direction 28 can be short and, for example, be present for a period of at least 20 milliseconds and at most 80 milliseconds, at least 10 milliseconds and at most 500 milliseconds, or at least 100 milliseconds and at most 200 milliseconds, wherein a shortening of the duration can be associated with a lower stress on components and performance losses, and a comparatively longer duration can increase the quality of the events transmitted thereby. According to embodiments, the duration depends on the design of the logic and is, for example, with reference to Fig. 7 selected so that it is greater than the delay set in state Z1 and / or less than the delay set in state Z7.

[0060] According to one embodiment, the source 78 is a part of the voltage converter 66 and / or the voltage converter 66 provides a function of the source, that is, it can be designed to carry out a modulation of the voltage U PV or the current I pv or I Steuer.

[0061] The current I control can be provided, for example, as a direct current, for example, in such a way as to still allow a current flow despite knowing the voltage drop across the body diodes 38 1 and / or 38 2. For example, the source 78 can have a current limiter and / or be configured to provide a constant current, which allows the source 78 to regulate a constant current.

[0062] For example, a body diode can cause a voltage drop of approximately 0.5 volts, which can be taken into account accordingly in the designs of the voltage converter 66 and / or the source 78.

[0063] In other words, Fig. 3 A system overview of a vehicle-integrated photovoltaic system with PV modules, smart PV modules 20 according to exemplary embodiments, a DC / DC converter, and an HV battery. A smart PV module can be understood as a PV module coupled to an intelligent electronic circuit described herein.

[0064] In other words, an electronic circuit according to embodiments can, in order to avoid the disadvantages of the prior art, ensure that, for example, no excessive voltage is present in the PV circuit, even during disconnection of the Service Disconnect Box. Electronic circuits described herein make it possible to establish a safe state of the PV modules and the PV circuit by disconnecting the PV circuit. This disconnection occurs close to the PV module and optionally without communication, i.e., an additional signal between the DC / DC converter and the smart PV module, i.e., the electronic circuit 10 and / or 20 in the form of a message to be transmitted, is not necessary. Instead, attention can be paid to the parameter voltage and current in the PV module, i.e., input and output, and the PV module can be switched on or off depending on the state.

[0065] Optionally, in addition to the inventive connection of the PV modules via the electronic circuit, further functionality can also be provided in the control device or the electronic circuit. Five different states are described in detail below for clarity: 1. Switching on 2. Maximum Power Point Tracking (MPPT) 3. Switching off due to short circuit 4. Switching off due to open circuit, for example when the string circuit is cut or interrupted and / or there is no current flow 5. Switching on due to shading 1. Connect

[0066] The activation of the Smart PV module can be triggered by a voltage source, such as source 78, providing a test signal or by the DC / DC converter. The test signal source can be switched on or activated and apply a positive voltage to the output of the Smart PV module, for which Fig. 4Starting from the state shown in point 1A, the voltage can be increased until it equals the sum of the open circuit voltage of the PV module U PV_in in Fig. 2and the voltage drop across the switches 36 1 and 36 2 , formed, for example, as MOSFETs, which is designated by the parameter U D_FET, in order to reach state point 1B. This means that the current can reverse, while the voltage in the string and at the circuit outputs can remain the same; only the voltage across the blocking switches reverses. The voltage of the test signal is further increased until a test current I Test_max is established, which flows through the body diodes of the switch(es) (MOSFETs) and the PV generator, which is reached at point 1C. Based on this, the control device can, for example, transfer the isolation device to the second state and switch on the switches S 1 and S 2 , which can lead to point 1D. If all series-connected smart PV modules of the system 300 are switched on, the test signal source is switched off (point 1E), and the PV module goes into idle mode.

[0067] In other words, Fig. 4 a UI characteristic curve of the PV module when switched on. 2. Maximum Power Point Tracking (MPPT)

[0068] Based on the Fig. 5 The MPPT is explained. If some or all Smart PV modules are connected, the DC / DC converter can become active and operate the entire PV generator at its maximum power point (MPP), see point 2B of the Fig. 5 For this purpose, an algorithm is used in the control of the DC / DC converter or voltage converter 66, which seeks this operating point by varying the voltage or current. To ensure that the smart PV module remains in this state, a sufficient input voltage U PV_in can be maintained, see Fig. 2 , as well as a limit value of the PV current I PV_SM not to be disputed.

[0069] In other words, Fig. 5 a UI characteristic curve of a PV module according to embodiments during MPP tracking. 3. Switch off / short circuit (SC)

[0070] If the output of the Smart PV module is short-circuited and the PV input voltage drops for a certain time, for example at least 200 milliseconds, at least 300 milliseconds or at least 400 milliseconds, e.g. 400 ms below the exemplary threshold N x U SM_Bypass with N being the number of Smart PV modules connected in series, as described in point 3A of the Fig. 6 As shown, the control device can be configured to transfer the isolating device to the first state and, for example, open switches S 1 and / or S 2 . U SM_Bypass denotes the forward voltage of the bypass diode, which can be between 10 mV and 1 V, for example, depending on whether it is actively implemented (with a switch and a controller) or passively implemented (e.g., a Schottky diode). The multiplication is valid for matching values ​​of U SM_Bypass in the different modules. 4. Switch off / idle (Open Circuit, OC)

[0071] If the voltage converter becomes inactive or if there is a cable break, the PV module can go into open circuit, as described, for example, in point 4A of the Fig. 6 The PV module current drops below a certain threshold. If this condition persists for a certain period of time, for example, if the module current I PV_SM is ≤ 100 mA and this occurs for a period of more than 200 milliseconds, more than 300 milliseconds, or more than 400 milliseconds, e.g., approximately 250 milliseconds, switches S 1 and / or S 2 can also be disconnected.

[0072] This examines the condition of missing or insufficient current. This can detect an open circuit in the string. The DC / DC converter can also cause the disconnection via open circuit by not drawing any current. In the latter case, the DC / DC converter would apply an open circuit voltage to the string, or this would occur automatically.

[0073] In other words, Fig. 6 a UI characteristic curve to explain switching off by short circuit and open circuit. 5. Switching on after shading

[0074] If shading occurs in a PV module and persists for so long that the voltage supply to the smart PV module is no longer guaranteed, particularly when using the internal voltage source 56, the switch S 1 and / or S 2 can be switched to an open state, i.e. the disconnection device is brought into the first state. After a specified time, the switches S 1 and S 2 switch or are brought into a conductive state, provided that a bypass current was flowing beforehand and a sufficiently high PV input voltage was present, which makes it possible to check whether the shading situation has ended. If shading continues, the module will disconnect again due to a drop in the supply voltage. If, on the other hand, there is no longer any shading, the module remains in the connected state. It may be sufficient to check whether a bypass current is flowing without measuring its level.

[0075] Fig. 7 shows an exemplary tabular representation of different states that can be assumed by control devices according to the invention. In particular, it is also shown here that a state that can exist in the control device can be two-stage, namely in a first stage "active or deactivated" and in a second stage "disconnected or connected". The first stage designates a degree of autonomy of the local module, the PV assembly. In an active state of the same, as is the case, for example, in states Z3, Z4, Z5, Z6 or Z7 at the beginning, a local decision can in principle be made as to whether, for example, from a disconnected

[0076] state is changed to a connected state, meaning the disconnecting device changes to the second state. In an inactive or deactivated state, such as may be present at the beginning of Z1, the logic of the control device can be designed such that the current flow along the second current flow direction 28 is perceived as an event to trigger this action. A connection via state Z1 can possibly occur at any time, regardless of a previously deactivated or activated state, as explained by columns S1, S2, and S3 of the table.

[0077] In the table, the symbol "x" in a field indicates that the state of the switches or the respective condition may be irrelevant. The times and / or voltages shown are merely examples and do not limit the present embodiments. Rather, other values ​​may also be applied depending on the components used.

[0078] As can be seen from the table of Fig. 7 As can be seen, the control device can be designed in embodiments to control the isolating device 24 from the second state to the first state based on a shutdown event, which means, for example, opening the switches. With reference to the table of Fig. 7Such shutdown events can be, for example, a new open circuit, permanent shading, or a string short circuit. Alternatively or additionally, the control device can be configured to recognize such a shutdown event as a shutdown event caused in the PV module 12 or the string 62 or the electronic circuit 10 or 20, i.e., a shutdown event that occurs from the voltage converter 66 beyond the service disconnect box 64.

[0079] According to one embodiment, the control device can be designed to control the disconnection device into the second state after the detected shutdown event depending on the current flow I control received via the string 62 along the second current flow direction 28. This means that according to the embodiment, such a signal or the current flow may be required. Optionally, but this is associated with additional components, an additional communication device can also be provided which transmits a substitute for such a signal, so that the current I control can trigger the change to the second state, but in some embodiments it represents one among several possibilities, while in other embodiments it represents the only possibility.In embodiments, an electronic circuit can be provided which is designed without a further communication interface, i.e. can be operated without communication.

[0080] According to one embodiment, the control device is designed to, in the event of a temporary drop in the power of the PV module, for example starting from state Z4 in the Fig. 7to state Z5, referred to as a longer shading situation, to temporarily switch the isolating device 24 to the first state. After a shutdown time, which is set, for example, as a predefined time value or is dependent on another event, the isolating device can be controlled to the second state independently of the current flow I control received via the string 62 along the second current flow direction 28. The control device is designed to then check whether the temporary power drop has ended. If it is detected that the end has not yet occurred, the first state can be changed back to. The time period is, according to an example in the Fig. 7explained and can be approximately 2,850 ms or a different value. In the table, the initial state for state Z4 is described as "Active," which means the decision to connect can be made locally in the control device. Such a test-initiated, decentralized connection is possible, for example, and may be limited to such states for safety reasons, if no short circuit or open circuit has been previously detected. In these cases, the control device can be configured to put itself into a deactivated state, in which it can possibly be reactivated and connected exclusively by the pulse in the second current flow direction and / or optional external reset events.

[0081] Fig. 8shows a schematic side sectional view of a vehicle 900, for example a truck, which comprises a PV system according to embodiments described herein, for example the PV system 300. As an alternative to a truck, the vehicle can also be in the form of any other vehicle, for example a boat or ship, a motorcycle, a car or an aircraft, for example a blimp, a motorless or motorized aircraft, a drone or the like.

[0082] Fig. 9shows a schematic flow diagram of a method 1000 according to an embodiment. The method 1000 can be used to connect a PV module to a PV string. A step 1010 comprises applying a control current directed opposite to the first current direction to an electronic circuit. The electronic circuit is coupled between the PV module and the PV string and is in a first state in which a disconnection device disconnects a current path running via the PV module, and in which a current supplied from the PV module to the PV string in a first current direction is prevented. A step 1020 comprises controlling the disconnection device in a second state in which the current flow along the first current direction is enabled in order to close the current path, based on the control current.

[0083] An advantage of the embodiments described herein is the communication-free connection and disconnection of the PV module, i.e., without a dedicated communication channel, to achieve a safe voltage of < 60 volts in the PV circuit. The disconnection can be achieved by one or two or more MOSFETs connected in series. By omitting a communication channel or communication link, an embodiment can be implemented inexpensively yet reliably. This does not preclude embodiments with an additional communication channel, for example, for other or additional applications.

[0084] Examples of implementations can be used in the field of vehicle-integrated photovoltaics. Furthermore, this solution can also be used in stationary photovoltaic systems to increase the safety of PV installations compared to existing solutions. Safe operation of a high-voltage PV system may only be possible by disconnecting the series connection of PV modules. The concepts described here enable a cost-effective solution that can operate without additional communication overhead.

[0085] Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device.

[0086] Depending on specific implementation requirements, embodiments of the invention may be implemented in hardware or software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-ray Disc, a CD, a ROM, a PROM, an EPROM, an EEPROM, or a FLASH memory, a hard disk, or other magnetic or optical storage device storing electronically readable control signals that can interact or cooperate with a programmable computer system to perform the respective method. Therefore, the digital storage medium may be computer-readable.Some embodiments according to the invention thus comprise a data carrier having electronically readable control signals capable of interacting with a programmable computer system such that one of the methods described herein is carried out.

[0087] In general, embodiments of the present invention can be implemented as a computer program product with a program code, wherein the program code is effective to perform one of the methods when the computer program product is run on a computer. The program code can also be stored, for example, on a machine-readable medium.

[0088] Other embodiments include the computer program for performing one of the methods described herein, wherein the computer program is stored on a machine-readable carrier.

[0089] In other words, one embodiment of the method according to the invention is thus a computer program comprising program code for performing one of the methods described herein when the computer program is run on a computer. Another embodiment of the method according to the invention is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program for performing one of the methods described herein is recorded.

[0090] A further embodiment of the method according to the invention is thus a data stream or a sequence of signals that represents the computer program for carrying out one of the methods described herein. The data stream or the sequence of signals can be configured, for example, to be transferred via a data communication connection, for example, via the Internet.

[0091] A further embodiment comprises a processing device, for example a computer or a programmable logic device, which is configured or adapted to carry out one of the methods described herein.

[0092] A further embodiment comprises a computer on which the computer program for performing one of the methods described herein is installed.

[0093] In some embodiments, a programmable logic device (e.g., a field-programmable gate array, an FPGA) may be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field-programmable gate array may interact with a microprocessor to perform any of the methods described herein. In general, in some embodiments, the methods are performed by any hardware device. This may be general-purpose hardware such as a computer processor (CPU) or method-specific hardware such as an ASIC.

[0094] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

Claims

1. Electronic circuit for a photovoltaic, PV, module, comprising: PV terminals (141, 142) for coupling to the PV module (12); and string terminals (161, 162) for coupling to a PV string (62); a current path (22) running between the PV terminals (141, 142) and the string terminals (161, 162), which current path (22) is configured to conduct an electric current generated in the PV module (12) in a first current flow direction (18) to the PV string; a disconnector (24) arranged between a first terminal of the PV terminals (141, 142) and a second terminal of the string terminals (161, 162), which disconnector (24) is configured to interrupt the current path (22) in a first state along the first current flow direction (18); and to close the current path (22) in a second state along the first current flow direction (18); characterized in that the electronic circuit includes a controller (26; 34) which is configured to acquire current flow information about a current flow in at least one sub-portion of the current path (22) along a second current flow direction (28) opposite to the first current flow direction (18); and to control the disconnector (24) from the first state into the second state based on the current flow information.

2. Electronic circuit according to claim 1, wherein the disconnector (24) is configured to acquire the current flow information from a pulse in the second current flow direction.

3. Electronic circuit according to claim 1 or 2, which is configured to acquire a pulse via the string by means of the current flow along the second current flow direction, which pulse indicates the current flow information, in order to change into the second state.

4. Electronic circuit according to one of the preceding claims, wherein the disconnector (24) comprises a semiconductor switch (361, 362) with a switchable current path (22) and a diode (381, 382) acting in parallel with the switchable current path (22), wherein the disconnector (24) is configured to conduct, in the first state of the disconnector (24), the current flow via the diode (381, 382) along the second current flow direction (28).

5. Electronic circuit according to one of the preceding claims, wherein the disconnector (24) comprises at least a first and a second semiconductor switch (361, 362), which are connected to one another in series or in parallel, with diodes (381, 382) acting along the second current flow direction (28).

6. Electronic circuit according to one of the preceding claims comprising a sensor means (44) which is configured to recognize a current flow along the second current flow direction; wherein the current flow information is based on the recognized current flow.

7. Electronic circuit according to one of the preceding claims, wherein the controller (26; 34) is configured to control the disconnector (24) from the second state into the first state based on a switch-off event.

8. Electronic circuit according to one of the preceding claims, wherein the controller (26; 34) is configured to temporarily switch the disconnector (24) into the first state upon a temporary power setback of the PV module (12), and to subsequently control it back into the second state independently of the current flow (ISteuer), acquired via the PV string (62), along the second current flow direction (28) to check whether a temporary power setback causing the switch-off has ended.

9. Electronic circuit according to one of the preceding claims, which is configured without a communication interface.

10. Electronic circuit according to one of the preceding claims, having a sensor means (44), which is configured to recognize a current flow along the second current flow direction; wherein the current flow information is based on the recognized current flow; wherein the sensor means (44) is configured to detect a voltage drop over a diode acting in parallel with a switch of the disconnector, wherein the voltage drop is causally related to the current flow; wherein the controller (26; 34) is configured to temporarily switch the disconnector (24) into the first state upon a temporary power setback of the PV module (12), and to subsequently control it back into the second state independently of the current flow (ISteuer), acquired via the PV string (62), along the second current flow direction (28) to check whether a temporary power setback causing the switch-off has ended.

11. Photovoltaic assembly (200) having: a PV module (12); and an electronic circuit (10; 20) coupled to the PV module (12) according to one of the preceding claims.

12. PV system (300) having: a plurality of PV assemblies (200) according to claim 11, serially connected in a PV string (62); an electric voltage converter (66) coupled to the PV string, which is configured to acquire and convert an electric voltage (UPV) based on the current flow (IPV) in the first current flow direction (18); and a source (78) for applying the current flow (ISteuer) in the second current flow direction (28); wherein the voltage converter (66) is configured to control the source (78) to switch at least one PV assembly (200) into the PV string (62).

13. PV system according to claim 12, wherein the source (78) is configured to provide the current (ISteuer) along the second current flow direction (28) as a direct current.

14. Vehicle (900) having a PV system (300) according to claim12 or 13.

15. Method (1000) for switching a photovoltaic, PV, module into a PV string, comprising the following steps: providing (1010) an electronic circuit with a control current directed opposite to the first current direction; wherein the electronic circuit is coupled between the PV module and the PV string and is present in a first state, in which a disconnector disconnects a current path running across the PV module, and in which a current of the PV module delivered in a first current direction to the PV string is prevented; controlling (1020) the disconnector into a second state, in which the current flow along the first current direction is enabled to close the current path based on the control current.