Semiconductor-based switching device and vehicle power supply system with semiconductor-based switching device

Abstract

The invention relates to a semiconductor-based switching device (10) for a battery-electrically drivable vehicle, comprising a first electrical interface (82) designed to be electrically connected to a vehicle-based charging interface (120), a second electrical interface (84) designed to be electrically connected to a vehicle-based traction battery (110), a current path (80) which electrically connects the two interfaces (82, 84) to one another, an electrically unidirectionally conductive semiconductor element (30) in the current path (80), an electrically bidirectionally conductive semiconductor switching element (20) in the current path (80) which is electrically connected in parallel with the unidirectionally conductive semiconductor element (30), a sensor unit (60) configured to measure the current and / or the voltage in the switching device (10), and a driver unit (50) configured to switch the electrically bidirectionally conductive semiconductor switching element (20) on the basis of the measured value from the sensor unit (60). The invention also relates to a vehicle power supply system (100) having a semiconductor-based switching device (10). The semiconductor-based switching device (10) can perform an abrupt emergency shutdown in the battery discharge direction in the event of overcurrents or short circuits. Nevertheless, relatively high current intensities can be transmitted in the battery charging direction by the parallel connection of the semiconductor components (20, 30).

Description

[0001] Bremen, April 10, 2026

[0002] Our reference number: PA 6931-02WO CHA / flin

[0003] Applicant: Pierburg GmbH

[0004] Registration number: Late registration

[0005] Pierburg GmbH

[0006] Alfred-Pierburg-Straße 1, 41460 Neuss

[0007] Semiconductor-based switching device and vehicle power supply system with semiconductor-based switching device

[0008] The present invention relates to a semiconductor-based switching device for a battery-electric vehicle. The invention further relates to a vehicle power supply system for a battery-electric vehicle.

[0009] The demands for increasing the charging capacity of battery-electric vehicles are constantly rising. The goal is to restore a large portion of the traction battery's capacity within relatively short charging times, thereby reducing waiting times at charging stations. Particularly for traction batteries with relatively high capacity, which are primarily used in commercial applications, especially in battery-electric trucks, the required battery voltages are currently 800 V and higher, and charging currents can reach up to 1500 A.

[0010] Accordingly, the safety requirements for the vehicle's electrical system are also high, as short circuits can damage the charging equipment. Such vehicles therefore have electrical switching devices connected between the traction battery and a vehicle-side charging interface, which can quickly interrupt the charging process in the event of a short circuit. Since conventional electromechanical switching devices are relatively slow, semiconductor-based switching devices, so-called solid-state relays, are typically used. These relays, with their semiconductor switching elements, ensure a rapid interruption of the charging process and are therefore significantly superior to conventional mechanical switching devices such as electromagnetic contactors or pyrotechnic current-disconnecting devices in terms of achievable switching times.

[0011] *20260287646*With a semiconductor-based switching device, switching times in the microsecond range can be achieved, enabling a rapid interruption of the electrical connection between the traction battery and the charging interface on the vehicle side.

[0012] To achieve these switching times, such semiconductor-based switching devices typically require expensive semiconductor switching elements, for example based on silicon carbide, due to the high charging currents. These elements must be able to carry the entire current load, making the entire switching device relatively expensive.

[0013] The present invention is based on the objective of creating a relatively cost-effective and semiconductor-based switching device with a relatively high switching speed, particularly for a vehicle power supply system.

[0014] This problem is solved according to the invention by a semiconductor-based switching device with the features of claim 1. Furthermore, this problem is solved according to the invention by a vehicle power supply system with the features of claim 9.

[0015] The semiconductor-based switching device according to the invention for a battery-electric vehicle comprises at least one first electrical interface designed to be electrically connected to a vehicle-side charging interface. Furthermore, the semiconductor-based switching device comprises at least one second electrical interface designed to be electrically connected to a vehicle-side traction battery. The semiconductor-based switching device is thus specifically designed to be electrically connected between the traction battery and the charging interface in a battery-electric vehicle. The semiconductor-based switching device according to the invention further comprises a current path that electrically connects the two interfaces, allowing current to flow between the first and second interfaces in both directions.

[0016] Furthermore, the semiconductor-based switching device according to the invention comprises at least one electrically unidirectionally conductive semiconductor element that is arranged in the current path and thus electrically connected between the first interface and the second interface. This is a semiconductor component that has a forward direction and a reverse direction and is therefore, apart from a small leakage current in the reverse direction, only conducts current in the forward direction. The term "forward direction" generally refers below to the forward direction of the unidirectionally conductive semiconductor element. Furthermore, the unidirectionally conductive semiconductor element is preferably designed such that the voltage applied to it must exceed a defined threshold value for the unidirectionally conductive semiconductor element to transition into the conducting state.The unidirectionally conductive semiconductor element can be designed, for example, as a thyristor or diode, whereby this does not refer to a parasitic diode, such as an inverse diode or body diode of a MOSFET, but rather a separate diode for power transmission.

[0017] The semiconductor-based switching device additionally comprises at least one electrically bidirectionally conductive semiconductor switching element arranged in the current path and thus electrically connected between the first and second interfaces. The bidirectionally conductive semiconductor switching element is therefore current-conducting in both directions. Furthermore, the bidirectionally conductive semiconductor switching element is switchable, such that it is electrically conductive in both directions when closed and electrically non-conductive when open. The bidirectionally conductive semiconductor switching element is preferably configured as a transistor, for example a JFET or MOSFET, preferably silicon carbide-based, or as an IGBT.These components are characterized in particular by their relatively fast switching time, but for cost reasons they are not designed for the entire current load that the switching device is intended to transmit in one direction through the unidirectionally conductive component. Furthermore, the bidirectionally conductive semiconductor switching element is electrically connected in parallel to the unidirectionally conductive semiconductor element. The unidirectionally conductive semiconductor element and the bidirectionally conductive semiconductor switching element are preferably each designed as separate components.

[0018] Furthermore, the switching device comprises at least one sensor unit configured to measure the current and / or voltage within the switching device. For this purpose, a current sensor is preferably arranged in the current path, which can, for example, be connected in series with the parallel circuit consisting of the unidirectionally conductive semiconductor element and the bidirectionally conductive semiconductor switching element, and which measures the current flowing in the current path. Alternatively, a voltage sensor can be used, which, for example, measures the voltage before and after the parallel circuit.

[0019] Additionally, the switching device includes at least one driver unit configured to switch the electrically bidirectional semiconductor switching element based on the measured value from the sensor unit. The measured value corresponds to the current or voltage measured by the sensor unit.

[0020] The semiconductor-based switching device can be designed as a self-contained module, whereby the driver unit and the sensor unit can also be arranged separately, i.e., outside the module.

[0021] By connecting the bidirectionally conductive semiconductor switching element and the unidirectionally conductive semiconductor element in parallel, the switching device according to the invention is designed to transmit relatively high currents, typically up to 1500 A, from the first interface to the second interface in the forward direction of the unidirectionally conductive semiconductor element. Such currents occur, for example, during the fast charging process of a battery-electric vehicle. The switching device is therefore particularly suitable for a vehicle power supply system of a heavy vehicle such as a truck.The relatively inexpensive, but high-current-capable, unidirectionally conductive semiconductor element carries a large portion of the current load when transmitting high currents. This means the more expensive bidirectionally conductive semiconductor switching element does not need to be designed for such high current loads, making the switching device relatively inexpensive to manufacture overall. Nevertheless, currents can be transmitted in both directions using the bidirectionally conductive semiconductor switching element, including in the reverse direction of the unidirectionally conductive semiconductor element (i.e., from the second interface to the first interface). However, the transmittable current is limited by the current-carrying capacity of the bidirectionally conductive semiconductor switching element.

[0022] The bidirectionally conductive semiconductor switching element is preferably designed for currents up to approximately 150 A. This corresponds, for example, to the current during the start-up phase of a charging process or the current during charging processes with relatively low charging power, which can be carried by the bidirectionally conductive semiconductor switching element alone. If the current-carrying capacity of the bidirectionally conductive semiconductor switching element is exceeded in the forward direction, the unidirectionally conductive semiconductor element switches to an electrically conductive state to relieve the bidirectionally conductive semiconductor switching element. This eliminates the need for a parallel connection of several costly bidirectionally conductive semiconductor switching elements.Nevertheless, according to the invention, it is not excluded that several bidirectionally conductive semiconductor switching elements are electrically connected in parallel to each other, in which case these are also electrically connected in parallel to the unidirectionally conductive semiconductor element. In principle, the unidirectionally conductive semiconductor element has a current-carrying capacity that is preferably at least twice, and particularly preferably at least four times, higher than that of the bidirectionally conductive semiconductor switching element.

[0023] In a particularly preferred embodiment of the switching device according to the invention, the driver unit comprises an evaluation unit configured to detect a short circuit using the measured value. For this purpose, a setpoint or setpoint range is defined in the evaluation unit, within which the current or voltage should lie in a defined operating mode. In the event of a significant deviation of the measured value, which occurs particularly in the case of a short circuit, the evaluation unit sends a signal to the driver unit. The driver unit is configured to switch the semiconductor switching element to a blocked state, i.e., to the open, non-conductive state, upon receiving the signal. This process occurs automatically and does not require an external control signal, for example, from a higher-level vehicle control unit, in order to minimize time delays during shutdown.

[0024] In a further particularly preferred embodiment of the switching device according to the invention, the unidirectionally conductive semiconductor element is configured as a unidirectionally conductive semiconductor switching element and is thus switchable. Furthermore, the driver unit is configured to switch the unidirectionally conductive semiconductor switching element based on the measured value from the sensor unit. Additionally or alternatively, the unidirectionally conductive semiconductor switching element can be switched by a higher-level control unit. The unidirectionally conductive semiconductor switching element can thus be actively connected in parallel to the bidirectionally conductive semiconductor switching element if required, particularly when the current-carrying capacity of the bidirectionally conductive semiconductor switching element is exceeded. In the low-ampere range, for example, at currents up to 100 A, the current flows only through the bidirectionally conductive semiconductor switching element.This eliminates the need for additional mechanical switching devices, such as relays.

[0025] In a further embodiment of the invention, the unidirectionally conductive semiconductor switching element is designed as a thyristor. The thyristor is typically designed for relatively high currents and preferably has a current-carrying capacity that is at least twice, and particularly preferably four times, that of the bidirectionally conductive semiconductor switching element. The thyristor has an anode, a cathode, and a so-called gate. The thyristor has a forward bias, in which a current can flow from the anode to the cathode, whereas it blocks a current flow in a reverse bias from the cathode to the anode. The anode is preferably electrically connected to the first interface, whereas the cathode is preferably electrically connected to the second interface. The thyristor is thus only unidirectionally conductive.The thyristor is triggered by the driver unit, for example, by a pulse signal applied to the gate. The thyristor then enters an electrically conductive state, the latching state, provided a defined latching current is present at the anode. Due to its latching properties, the thyristor maintains this state until the latching current falls below this threshold. The thyristor cannot be actively switched off; instead, it switches off automatically as soon as the current at the anode drops below the latching current. Because of its composition, a thyristor is a cost-effective semiconductor component and can still transmit relatively high currents, making this semiconductor-based switching device relatively inexpensive to manufacture.

[0026] In a further advantageous embodiment of the invention, the electrically bidirectionally conductive semiconductor switching element comprises at least one field-effect transistor (FET) and / or at least one bipolar transistor. Preferably, the bidirectionally conductive semiconductor switching element is configured as a JFET, MOSFET, or IGBT, for example, based on silicon or silicon carbide, which exhibit extremely fast switching times and thus enable rapid switching of the bidirectionally conductive semiconductor switching element.

[0027] In a further advantageous embodiment, the semiconductor-based switching device comprises a surge protection device that is electrically connected in parallel to the electrically unidirectionally conductive semiconductor element and the electrically bidirectionally conductive semiconductor switching element. The surge protection device can, for example, be implemented as an RC circuit, also known as a snubber, which is typically a series circuit consisting of a resistor and a capacitor. Alternatively, the surge protection device can comprise or be formed by semiconductor components.The overvoltage protection device prevents damage to the bidirectionally conductive semiconductor switching element or the unidirectionally conductive semiconductor element from voltage spikes that occur during a shutdown of the bidirectionally conductive semiconductor switching element, for example in the event of a short circuit, by attenuating the voltages accordingly. Particularly preferably, the semiconductor-based switching device comprises a third electrical interface and a freewheeling diode, wherein the freewheeling diode is electrically connected between the third interface and the current path. In this case, the freewheeling diode connects, in particular, the positive current path and the negative current path between a charging device and a traction battery.The freewheeling diode is thus arranged on the inlet side of the unidirectionally conductive semiconductor element with respect to the forward direction, so that when the switching device is switched off, for example by switching off the bidirectionally conductive semiconductor switching element, a current applied to the first interface or third interface, for example a battery discharge current, can circulate via the freewheeling diode.

[0028] Advantageously, the semiconductor-based switching device according to the invention is designed as a single switching module. For example, all components can be arranged on a common circuit board, forming a so-called solid-state relay that can be relatively easily installed in a vehicle. Alternatively, the solid-state relay can comprise several circuit boards. In this case, the components are interconnected with low inductance, resulting in particularly short switching times, making the switching device especially suitable for emergency shutdown in the event of a short circuit. The switching module is, for example, part of the charging interface architecture and is installed, for example, in the area of ​​a charging socket.

[0029] A vehicle power supply system according to the invention for a battery-electric vehicle comprises a traction battery designed to supply electrical energy to a vehicle-mounted electric traction motor. This can be, for example, a purely electric vehicle or a hybrid vehicle with an internal combustion engine that can also be driven purely electrically by means of an electric traction motor. The electrically driven vehicle is particularly preferably a commercial vehicle, for example, an electric truck, in which charging currents of up to 1500 A are achieved during a charging process. The traction battery provides the vehicle's electrical drive energy.The traction battery has a positive electrode (positive terminal) through which current flows into the battery during charging and out during discharging. It also has a negative electrode (negative terminal). Furthermore, the vehicle's electrical system has a charging interface designed to connect to an external DC power source, such as an external charging device. This charging interface can be, for example, a charging socket into which a charging plug from the external charging device, such as a charging station, can be inserted to establish an electrical connection between the traction battery and the charging station and to charge the battery. Alternatively, the charging interface can be designed to connect to an electrical load.The vehicle's electrical system also includes a positive current path (positive path) between the charging interface and the positive electrode of the traction battery. During charging, current flows from the charging interface to the positive electrode, and during discharging, current flows from the positive electrode to the charging interface via this positive current path. Furthermore, the vehicle's electrical system includes a negative current path (negative path) between the charging interface and the negative electrode of the traction battery, which completes the circuit between the charging station and the traction battery.

[0030] Furthermore, the vehicle power supply system comprises a semiconductor-based switching device according to the invention, which is arranged in the positive current path or the negative current path.

[0031] The switching device according to the invention, due to its aforementioned design, is specifically designed to interrupt the electrical connection between the traction battery and the charging interface within fractions of a second when a short circuit occurs in a vehicle power supply system according to the invention, which could lead to uncontrolled discharge of the traction battery. This prevents any significant current from flowing uncontrollably from the traction battery to the charging interface and from there to the charging station, thus preventing the traction battery from discharging. The switching device according to the invention therefore serves as an emergency shutdown in the event of a short circuit. For this purpose, the switching device is arranged such that the blocking direction of the unidirectionally conductive semiconductor element corresponds to the discharge direction.Accordingly, current can only flow in the forward direction through the unidirectionally conductive semiconductor element from the charging interface to the traction battery during a charging process. Conversely, during a discharge process, current can only flow in the reverse direction through the bidirectionally conductive semiconductor switching element, not through the unidirectionally conductive semiconductor element. In the event of a short circuit, for example, due to a malfunction in the charging peripherals, the discharge process can be abruptly interrupted by the opening of the bidirectionally conductive semiconductor switching element, thanks to its fast switching time. The driver unit controls the bidirectionally conductive semiconductor switching element based on the sensor reading. Consequently, significant discharge of the traction battery and damage to the components of the switching device and the vehicle's power supply system can be prevented.

[0032] Due to the bidirectional nature of the bidirectionally conductive semiconductor switching element, so-called Vehicle-to-X applications, in which controlled discharge of the traction battery occurs with significantly lower transmission power, can be implemented cost-effectively. In particular, in a Vehicle-to-Grid operation, where the vehicle's traction battery is used as a buffer storage device for the public power grid, the current flows in a controlled discharge direction from the traction battery through the switching device to the charging interface. Because the unidirectionally conductive semiconductor element is blocked in the discharge direction, the current can only flow through the bidirectionally conductive semiconductor switching element, meaning that the bidirectionally conductive semiconductor switching element must be able to handle the current load in Vehicle-to-Grid operation on its own.Therefore, the design of the current-carrying capacity of the bidirectionally conductive semiconductor element is primarily based on the current strength achieved in vehicle-to-grid operation. This is typically on the order of approximately...

[0033] 100 A. To activate the Vehicle-to-Grid operation, the bidirectionally conductive semiconductor switching element is switched to the closed state by the driver unit, so that a controlled current can flow in the discharge direction through the bidirectionally conductive semiconductor switching element.

[0034] In a preferred embodiment of the vehicle power supply system according to the invention, the vehicle power supply system comprises a control unit configured to control the driver unit. The control unit is preferably superior to the driver unit and communicates with one or more vehicle-side control units. Thus, the driver unit, and consequently the switching device, can be controlled and monitored externally.

[0035] In a further advantageous embodiment of the vehicle power supply system according to the invention, the freewheeling diode of the switching device electrically connects the positive and negative current paths. With respect to the charging direction, the freewheeling diode can be connected in series before or after the parallel connection consisting of the unidirectionally conductive semiconductor element and the bidirectionally conductive semiconductor switching element. In particular, the freewheeling diode is electrically connected between the switching device and the charging interface and is connected in parallel with the traction battery. If the switching device is switched off, for example in the event of a short circuit, the battery current of the traction battery can flow from the charging interface back to the charging interface via the freewheeling diode, thereby decoupling the inductances of the switching device from the charging interface.

[0036] In a further advantageous embodiment of the vehicle power supply system according to the invention, the vehicle power supply system comprises a mechanical switching device that is electrically connected in series with the semiconductor-based switching device. Particularly preferably, the vehicle power supply system has several mechanical switching devices that can be arranged in the positive current path and / or the negative current path. The control unit is configured to switch the mechanical switching device. The mechanical switching device can, for example, be designed as an electromagnetic contactor or as a pyrotechnic current disconnector. Furthermore, several such mechanical switching devices can be electrically connected in series in both the positive current path and the negative current path.The mechanical switching device can thus additionally permit or interrupt a charging or discharging process on the vehicle side; however, due to its relatively slow switching time compared to the semiconductor-based switching device, the mechanical switching device is not suitable for emergency shutdown in the event of a short circuit. In particular, the mechanical switching device enables galvanic isolation between the traction battery and the charging interface.

[0037] An embodiment of the present invention is described below with reference to the accompanying figures. These show:

[0038] Fig. 1 shows a schematic circuit diagram of a semiconductor-based switching device according to the invention, and

[0039] Fig. 2 shows a schematic circuit diagram of a vehicle power supply system according to the invention with a semiconductor-based switching device according to Figure 1.

[0040] Fig. 1 shows a semiconductor-based switching device 10 according to the invention for the positive current path of a vehicle power supply system 100 of a battery-electric vehicle. It should be clear that a corresponding switching device for the negative current path can alternatively or additionally be formed using the listed components. The semiconductor-based switching device 10 is designed as a single switching module 12 in which all components are electrically interconnected with low inductance. The semiconductor-based switching device 10 comprises a first electrical interface 82, which is designed to be electrically connected to a vehicle-side charging interface 120, as shown in Fig. 2.The charging interface 120 can, for example, be configured as a charging socket located on the outside of the battery-electric vehicle, into which a charging plug 210 of an external DC power source 200, such as a charging station 220, can be inserted to electrically connect the battery-electric vehicle to the charging station 220. The semiconductor-based switching device 10 further comprises a second electrical interface 84, which is designed to be electrically connected to a vehicle-side traction battery 110 that serves as an energy source for a vehicle-side traction motor that generates the vehicle's propulsion. The two electrical interfaces 82 and 84 are electrically connected to each other via a current path 80.

[0041] The semiconductor-based switching device 10 further comprises an electrically unidirectionally conductive semiconductor element 30 in the current path 80. The unidirectionally conductive semiconductor element 30 is configured as a unidirectionally conductive semiconductor switching element 32 and is therefore switchable. In this case, the unidirectionally conductive semiconductor switching element 32 is configured as a thyristor 34, which has a positive electrode (positive terminal) 31, a negative electrode (negative terminal) 33, and a gate 35. The thyristor 34 is electrically unidirectionally conductive, so that, apart from a small leakage current, current can only flow from the positive electrode 31 to the negative electrode 33. The positive electrode 31 is electrically connected to the first interface 82, whereas the negative electrode 33 is electrically connected to the second interface 84.Gate 35 is electrically connected to a driver unit 50, so that thyristor 34 can be triggered by a pulse signal from the driver unit 50 at gate 35. If a sufficiently high latching current flows at the positive electrode 31 during triggering, thyristor 34 enters the latching state and is electrically conductive in one forward direction, allowing current to flow through the current path 80 from the first interface 82 to the second interface 84. Thyristor 34 also has a reverse bias, in which current flow from the negative electrode 33 to the positive electrode 31 is blocked.

[0042] The semiconductor-based switching device 10 also features an electrically bidirectionally conductive semiconductor switching element 20 in the current path 80. The bidirectionally conductive semiconductor switching element 20 is preferably configured as a field-effect transistor 22, in this case as an n-channel MOSFET 24. The MOSFET 24 has the following terminals: Source 21, Drain 23, and Gate 25. Additionally, the MOSFET 24 has a so-called inverse diode 28, which prevents the MOSFET 24 from interrupting the charging currents. The Gate 25 is electrically connected to the driver unit 50, so that the MOSFET 24 can be switched by means of a signal from the driver unit 50. In the closed state, the MOSFET 24 is conductive in both directions, so that a current can flow either from the first interface 82 to the second interface 84 or from the second interface 84 to the first interface 82.

[0043] The MOSFET 24 is typically designed for currents of approximately 100 A, whereas the thyristor 34 is designed for currents of approximately 1400 A, with the possibility of additional safety margins. Up to 100 A, the MOSFET 24 primarily carries the current load. If the forward current exceeds 100 A, the additional current can be primarily routed through the thyristor 34 by the driver unit 50, allowing the semiconductor-based switching device 10 to carry a total forward current of up to 1500 A. However, the driver unit 50 can also activate the thyristor 34 even below 100 A.

[0044] In reverse bias, current flow is only possible via the MOSFET 24, so the current-carrying capacity of the semiconductor-based switching device 10 in reverse bias is limited to the current-carrying capacity of the MOSFET 24.

[0045] The semiconductor-based switching device 10 further comprises a sensor unit 60, which is configured as a current sensor 62. The current sensor 62 is connected in series with the MOSFET 24 and the thyristor 34 and is located in the current path 80 between the thyristor 34 and the second interface 84. The current in the current path 80 is measured by the current sensor 62 and transmitted to the driver unit 50. To evaluate the measured value from the current sensor 62, the driver unit 50 has an evaluation unit 90, which evaluates the measured value from the current sensor 62. Based on the measured value, the driver unit 50 can switch the MOSFET 24 and the thyristor 34. The evaluation unit 90 is also configured to detect an overcurrent, e.g., in the case of a short circuit, using the measured value.For this purpose, the evaluation unit 90 compares the measured value of the current sensor 62 with a target value or a target value range, so that in case of deviations a switching signal can be transmitted to the driver unit 50, whereupon the driver unit 50 can switch the MOSFET 24, for example, into a blocked state in which the current flow is interrupted. The semiconductor-based switching device 10 also has a control interface 88 which is connected to the driver unit 50, so that the driver unit 50 can be connected, for example, to an external control unit 150.

[0046] Furthermore, the semiconductor-based switching device 10 comprises an overvoltage protection device 40, which is configured here as an RC circuit 42, wherein the RC circuit 42 is a series connection of a capacitor 44 and an ohmic resistor 46. The RC circuit 42 is electrically connected in parallel with the MOSFET 24 and the thyristor 34. The RC circuit 42 is also arranged such that the resistor 46 is connected to the first interface 82, whereas the capacitor 44 is connected to the second interface 84.

[0047] The semiconductor-based switching device 10 additionally comprises a third electrical interface 86 and a freewheeling diode 70. The freewheeling diode 70 has an anode 71 and a cathode 73. The switching device can be connected to another current path via the third electrical interface 86. The freewheeling diode 70 is electrically connected between the third interface 86 and the current path 80, with the anode 71 being electrically connected to the third electrical interface 86 and the cathode 73 to the current path 80. This allows a current in a circuit closed via the connection between the first interface 82 and the third interface 86 to circulate through the freewheeling diode 70 and thus be inductively decoupled from the current path 80 containing the thyristor 34 and the MOSFET 24.

[0048] Fig. 2 shows a vehicle power supply system 100 for a battery-electric vehicle, in particular a truck. The vehicle power supply system comprises a traction battery 110, which has a positive electrode (positive terminal) 111 and a negative electrode (negative terminal) 112. The traction battery 110 can, for example, be a lithium-ion battery, by means of which electrical energy is provided to operate an electric traction motor to propel the vehicle. The vehicle power supply system 100 further comprises a charging interface 120, which can, for example, be arranged as a charging socket on the outside of the vehicle and into which a charging plug 210 of an external DC power source 200, for example a charging station 220, can be inserted, thereby charging the traction battery 110 by means of direct current.

[0049] A positive current path at positive battery potential (high-side current path) 114 is formed between the positive electrode 111 and the charging interface 120. This path is formed by an electrical conductor, for example, a cable. A negative current path at negative battery potential (low-side current path) 116 is formed between the negative electrode 112 and the charging interface 120. This path is also formed by an electrical conductor, for example, a cable. The positive electrode 111 and the negative electrode 112 are connected to the corresponding poles of the charging interface 120. During a charging process, current can flow from the charging station 220, via the charging plug 210 and the charging interface 120, through the positive current path 114 to the positive electrode 111 of the traction battery 110, thus electrically charging the traction battery 110.During a discharge process, the current flows in the reverse direction from the positive electrode 111 of the traction battery 110 through the positive current path 114 to the charging interface 120 and from there via the charging plug 210 into the charging station 220.

[0050] The semiconductor-based switching device 10 is arranged in the positive current path 114, with the first electrical interface 82 being electrically connected to the charging interface 120, whereas the second interface 84 is electrically connected to the positive electrode 111 of the traction battery 110. During a charging process, the current thus flows through the semiconductor-based switching device 10. As already described in Fig. 1, the thyristor 34 is only conducting in the forward direction, i.e., from the first interface 82 to the second interface 84, so that during a charging process, i.e., towards the traction battery 110, the current can flow through the thyristor 34, whereas during a discharging process, i.e., towards the charging interface 120, the current cannot flow through the thyristor 34 due to its unidirectional nature.During a charging process, currents of 1500 A can be transmitted, whereas during a discharging process, the discharge currents are limited to a current of approximately 100 A by the current carrying capacity of the MOSFET 24.

[0051] The driver unit 50 is connected to a higher-level control unit 150 of the vehicle via the control interface 88, enabling the driver unit 50 to receive control commands from the control unit 150 and to send diagnostic data.

[0052] At lower currents of up to 100 A, initially only the MOSFET 24 is closed. When the current reaches its permissible current-carrying capacity, which is determined primarily by the current sensor 62, the driver unit 50 switches the thyristor 34 into the conducting state by means of a pulse signal to the gate 35. The necessary latching current of the thyristor 34 is already achieved through its design, so that the thyristor 34 enters the latching state. From this point on, the thyristor 34 and the MOSFET 24 are electrically connected in parallel, allowing the majority of the charging current to flow to the traction battery 110 via the thyristor 34. The evaluation unit 90 continuously monitors the current in the positive current path 114. As soon as a short circuit occurs during the charging process, for example due to a malfunction in the charging peripherals, the current in the positive current path 114 drops rapidly.Initially, the current drops below the holding current value of thyristor 34, causing thyristor 34 to switch off and enter a non-conducting state. The current then flows only through MOSFET 24. If the current drops so low that it enters the negative range, the current flow reverses, resulting in an uncontrolled discharge of the traction battery 110. The current now flows through the positive current path 114 towards the charging interface 120, with the current rising rapidly and potentially reaching values ​​in the double-digit kA range without protective measures. Such a short circuit is detected by the current sensor 62, causing the evaluation unit 90 to send a signal to the driver unit 50. The driver unit 50 then switches MOSFET 24 to the open state, thus abruptly interrupting the current flow.This process occurs within microseconds, thus preventing damage to the components, particularly those in the charging peripherals. In particular, this prevents fires from occurring in the area of ​​charging plug 210 or charging interface 120.

[0053] Furthermore, the semiconductor-based switching device 10 enables Vehicle-to-X operation, for example, Vehicle-to-Grid operation. In this case, a controlled discharge of the traction battery 110 takes place. The vehicle power supply system 100 is electrically connected to the charging station 220, whereby the charging station 220 can draw current from the traction battery 110 as needed, so that the traction battery 110 serves as a buffer storage device for public or private power grids. The transmissible current is limited to the current-carrying capacity of the MOSFET 24, typically 100 A.

[0054] The freewheeling diode 70 electrically connects the positive current path 114 and the negative current path 116 by connecting its anode 71 to the negative current path 116 and its cathode 73 to the positive current path 114, allowing current to flow from the negative current path 116 to the positive current path 114. In the event of a short circuit, the battery current of the traction battery 110 can flow from the charging interface 120 back to the charging interface 120 via the freewheeling diode 70, thereby decoupling the inductances of the semiconductor-based switching device 10 from the charging interface 120. Furthermore, mechanical switching devices 130 and 140, each designed as an electromechanical contactor, are arranged in the positive current path 114 and the negative current path 116. Opening these devices provides additional galvanic isolation between the traction battery 110 and the charging interface 120.

[0055] In addition, the vehicle power supply system has 100 voltage sensors 160, 170 which are assigned to the control unit 150, so that the control unit 150 can measure the voltage in the vehicle power supply system 100.

[0056] Furthermore, additional switching elements 180, 190 are arranged in the positive current path 114 and in the negative current path 116, which can be designed, for example, as a pyrotechnic current separator or as a mechanical relay, and which are used as additional safety devices.

Claims

Claims 1. Semiconductor-based switching device (10) for a battery-electrically powered vehicle, comprising: at least one first electrical interface (82) designed to be electrically connected to a vehicle-side charging interface (120), at least a second electrical interface (84) designed to be electrically connected to a vehicle-side traction battery (110), at least one current path (80) that electrically connects the two interfaces (82, 84), at least one electrically unidirectionally conductive semiconductor element (30) per current path (80), at least one electrically bidirectionally conductive semiconductor switching element (20) in the current path (80) which is electrically connected in parallel to the unidirectionally conductive semiconductor element (30), at least one sensor unit (60) configured to measure the current and / or voltage in the switching device (10) and at least one driver unit (50) configured to switch the electrically bidirectionally conductive semiconductor switching element (20) based on the measured value of the sensor unit (60).

2. Semiconductor-based switching device (10) according to claim 1, wherein the driver unit (50) has an evaluation unit (90) configured to detect an overcurrent using the measured value, wherein the driver unit (50) is configured to switch the semiconductor switching element (20) to a blocked state upon detection of an overcurrent.

3. Semiconductor-based switching device (10) according to claim 1 or 2, wherein the unidirectionally conductive semiconductor element (30) is configured as a unidirectionally conductive semiconductor switching element (32) and wherein the driver unit (50) is configured to switch the unidirectionally conductive semiconductor switching element (32) based on the measured value of the sensor unit (60).

4. Semiconductor-based switching device (10) according to claim 3, wherein the unidirectionally conductive semiconductor switching element (32) is configured as a thyristor (34).

5. Semiconductor-based switching device (10) according to any one of the preceding claims, wherein the electrically bidirectionally conductive semiconductor switching element (20) comprises at least one field-effect transistor (22) and / or at least one bipolar transistor.

6. Semiconductor-based switching device (10) according to one of the preceding claims, comprising an overvoltage protection device (40) which is electrically connected in parallel to the electrically unidirectionally conductive semiconductor element (30) and the electrically bidirectionally conductive semiconductor switching element (20).

7. Semiconductor-based switching device comprising, according to one of the preceding claims, a third electrical interface (86), and at least one freewheeling diode (70), wherein the freewheeling diode (70) is electrically connected between the third interface (86) and the current path (80).

8. Semiconductor-based switching device (10) according to one of the preceding claims, wherein the semiconductor-based switching device (10) is designed as a single switching module (12).

9. Vehicle power supply system (100) for a battery-electric vehicle, comprising: a traction battery (110) having a positive electrode (111) and a negative electrode (112), wherein the traction battery (110) is designed to supply electrical energy to a vehicle-side electric traction motor, a charging interface (120) designed to be connected to an external DC power source (200) or an electrical consumer, a positive current path (114) between the charging interface (120) and the positive electrode (111), a negative current path (116) between the charging interface (120) and the negative electrode (112), and a semiconductor-based switching device (10) according to one of the preceding claims, which is arranged in the positive current path (114) and / or the negative current path (116).

10. Vehicle power supply system (100) according to claim 9, comprising a control unit (150) configured to control the driver unit (50).

11. Vehicle power supply system according to claim 9 or 10, wherein the freewheeling diode (70) electrically connects the positive current path (114) and the negative current path (116).

12. Vehicle power supply system (100) according to one of claims 9-11, comprising at least one mechanical switching device (130) which is electrically connected in series with the semiconductor-based switching device (10).

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