Power supply device

Abstract

The invention relates to a power supply device, in particular to a power supply circuit (1) comprising at least two power supply branches (2a, 2b), where each power supply branch (2a, 2b) comprises: a first semiconductor switch (3a, 3b) configured to be electrically connected to a power source; a second semiconductor switch (4a, 4b) connected in series with the first semiconductor switch (3a, 3b) and electrically connected to the common output (3) of the power supply circuit (1); and a first resistor (5a, 5b) wherein a first end of the first resistor (5a, 5b) is electrically connected to an electrical connection between the first semiconductor switch (3a, 4b) and the second semiconductor switch (4a, 4b) and a second end of the first resistor (5a, 5b) is configured to be electrically connected to a reference potential.

Description

Technical Field

[0001] The present invention relates to a power supply circuit, in particular to a power supply circuit for automotive applications. Background Art

[0002] Redundant power supplies are used in a wide variety of applications, from critical computer systems to vehicles. The basis of a redundant power supply is two or more power supplies connected in parallel. Even in the event of a failure of one of the power supplies, the other power supply is still able to supply power to the load connected to the redundant power supply. In this way, redundancy increases robustness, fail-safety and availability.

[0003] However, what is needed is a method to monitor the status of the redundant power supply itself and be able to detect a possible fault in one of its branches in order to initiate corresponding measures. At the same time, such additional safety measures should be implemented with a minimum of additional components to reduce complexity and cost. In addition, for certain applications, the redundant power supply should be able to supply high currents to external loads. Summary of the invention

[0004] Therefore, in a first aspect, the present invention relates to a power supply circuit comprising at least two power supply branches, wherein each power supply branch comprises: a first semiconductor switch, which is configured to be electrically connected to a power supply; a second semiconductor switch connected in series with the first semiconductor switch and electrically connected to a common output terminal of the power supply circuit; and a first resistor, wherein a first end of the first resistor is electrically connected to a connection between the first semiconductor switch and the second semiconductor switch, and a second end of the first resistor is configured to be electrically connected to a reference potential.

[0005] The semiconductor switch allows a specific supply branch to be disconnected from the common output of the supply circuit. This can be used for diagnostic and test purposes, as will be described in more detail below. In addition, it allows a faulty supply branch to be disconnected from the common output, so that the remaining non-faulty branches can still supply power to the common output and the connected loads. Furthermore, in certain cases, all supply branches can be shut down to meet certain safety goals, such as avoiding reverse current flow into the supply circuit. Finally, semiconductor switches such as field effect transistors (FETs) can be provided with a low on-resistance (R) such as, for example, 1 mΩ. DS(on) ), which allows high currents to flow through the supply branches with low internal heat dissipation losses. In this way, voltage can be provided to high-power external loads.

[0006] At the same time, one end of the resistor in each power supply branch is configured to be electrically connected to the connection of the two semiconductor switches, and the other end is configured to be electrically connected to a defined reference potential, such as ground. In operation, if the two semiconductor switches in the first power supply branch are disconnected and the switch in the other power supply branch is turned on, the potential at the resistor is expected to match the reference potential. If the measured potential does not match the expected (reference) potential, this indicates a short circuit fault, such as from drain to source, in one or both semiconductor switches of the disconnected power supply branch. Therefore, the failure of the semiconductor switch can be detected, and the power supply circuit can be shut down with the help of the (intact) semiconductor switch, thereby avoiding additional damage.

[0007] The power supply circuit according to the invention also allows to diagnose and test whether each power supply branch individually provides the expected voltage to the common output terminal of the power supply circuit. To this end, the first power supply branch can be disconnected by its corresponding semiconductor switch, while the other power supply branch can be connected by its corresponding semiconductor switch. Then, it is expected that the output voltage at the common output terminal of the power supply circuit corresponds to the nominal voltage, i.e. the input voltage of the power supply circuit. If this is not the case, for example the voltage is substantially below the nominal voltage or even at ground, this indicates that one or both semiconductor switches that connect the power supply branches are faulty.

[0008] In the context of the present invention, it is important that each power supply branch can be connected to one or more power supplies that are independent of one or more power supplies that supply other power supply branches. Therefore, each power supply branch can be powered independently, and the reliability of the system is significantly increased.

[0009] Furthermore, during normal operation and by appropriately controlling the state of the semiconductor switches, only one supply branch is open at the same time, i.e., supplying power to the common output of the power supply circuit. In this way, no reverse current can flow into the inactive supply branch. The circuit thus has a "priority" supply branch that is switched on under nominal conditions (e.g., in the case of a vehicle, with the ignition "on"). Only when the active supply branch voltage is too low is it switched off and another supply branch switched on. In this way, failover safety can be achieved. However, for diagnostic purposes in non-critical conditions (e.g., in the case of a vehicle when the ignition is "off"), it is permitted to switch to the inactive supply branch for a short period of time.

[0010] Each power supply branch may also include a second resistor, a first end of which is electrically connected to the connection between the first semiconductor switch and the second semiconductor switch, and a second end of which is electrically connected to the common output terminal of the power supply circuit so as to form a voltage divider with the first resistor. Therefore, in the context of the present invention, the second resistor is optional. Using a second resistor and forming a voltage divider with the first resistor allows the expected potential between the first and second semiconductor switches to be adjusted. For example, in the case of resistors with the same resistance, if the reference potential (connected to the second end of the first resistor) is grounded, the defined potential can be half the supply voltage.

[0011] The semiconductor switch may be a MOSFET. MOSFETs can switch high load currents with relatively small control currents and fast switching times. In addition, they can provide the low on-resistance (R) required to power high power external loads. DS(on) ).

[0012] The first semiconductor switch and / or the second semiconductor switch may include overcurrent protection. For example, if the current flowing through the switch exceeds a predetermined threshold, the semiconductor switch may be disconnected. In this case, overheating and damage to the switch and the corresponding power supply branch may be avoided.

[0013] The power supply circuit may also include a controller configured to switch the semiconductor switch, receive an electrical signal corresponding to the potential at the first end of the first resistor, and / or receive an electrical signal corresponding to the potential at the common output terminal of the power supply circuit. In this way, the controller can perform a self-test of the power supply circuit and can disconnect the faulty power supply branch or the entire power supply circuit, as will be described in more detail below. The controller may be a microcontroller. The controller may have an automotive safety integrity level-(ASIL)-B-qualification, more preferably ASIL-C and most preferably ASIL-D qualification. The electrical signal may directly correspond to the corresponding potential. In this case, the controller may include an analog-to-digital converter (ADC) to convert the potential into its digital representation. The ADC input of the controller may be directly connected to the corresponding measurement point in the circuit. Alternatively, one or more operational amplifiers and / or impedance converters may be arranged between the measurement point and the ADC input of the controller.

[0014] The power supply circuit may further include a measuring unit configured to measure the potential at the first end of the first resistor and / or the potential at the common output terminal of the power supply circuit, wherein the measuring unit is electrically connected to the controller. The measuring unit may include an analog-to-digital converter (ADC). The ADC may be electrically connected to the controller. In this case, the electrical signal corresponding to the potential and fed to the controller is a digital signal representing the measured potential. Using an ADC allows the potential measured at the output terminal of the semiconductor switch to be mapped to a digital value, which can be read by the controller for use in the control software executed at the controller.

[0015] The controller may be configured to output a fault signal and / or set a fault flag if the potential at the first end of the first resistor deviates from a first predetermined value by a first predetermined amount and / or if the potential at the common output terminal of the power supply circuit (1) deviates from a second predetermined value by a second predetermined amount. In this way, the controller may detect a fault and take appropriate action. For example, a warning may be provided to the driver of the vehicle, or the vehicle may refuse to restart if a fault is detected.

[0016] The first semiconductor switch and the second semiconductor switch may include a forward direction and an opposite reverse direction, wherein the forward direction of the first semiconductor switch is configured to operate in the reverse direction and the second semiconductor switch is configured to operate in the forward direction. The forward and reverse directions of the semiconductor switches may be defined by their body diodes.

[0017] The supply circuit may comprise two supply branches. This provides failover if one of the two supply branches exhibits a fault. Using two branches greatly increases robustness, fail-safety and availability, while requiring only a minimum of additional components.

[0018] The power supply circuit may be configured for automotive applications. Modern automobiles include many functions controlled by electronic control units that benefit from a power supply for safety and availability. This is particularly true for safety-critical functions used for assisted and / or automated driving, such as in self-driving cars.

[0019] Another aspect of the invention relates to a method for diagnosing a power supply circuit as disclosed herein, wherein the power supply circuit (1) comprises at least two power supply branches. The method comprises the following steps: disconnecting a first semiconductor switch and a second semiconductor switch in a first power supply branch; connecting the first semiconductor switch and the second semiconductor switch in a second power supply branch; and measuring the potential at a first end of a first resistor in the first power supply branch (4a).

[0020] The method may further comprise the steps of: diagnosing the presence of a fault in the first supply branch if the measured potential at the first end of the first resistor deviates from the first predetermined value by a first predetermined amount and / or if the potential at the first end of the first resistor matches a second predetermined value within a first predetermined tolerance; and disconnecting all semiconductor switches in response to diagnosing a fault in the first supply branch. Thus, it is equivalent whether the potential deviates from the first predetermined value or whether the potential matches a second predetermined value different from the first predetermined value. For example, a fault may be diagnosed if the potential deviates from 0V by at least 0.5V or if it matches 12V within a tolerance of 1V.

[0021] The mentioned diagnostic step allows testing for short circuits, in particular short circuits between the drain and source of one of the semiconductor switches in the first supply branch, since any current flowing into this supply branch will result in an unexpected voltage drop across the resistor. By changing the roles of the first and second supply branches, the other (second) supply branch can be diagnosed in a similar manner.

[0022] The method may further comprise the step of measuring the potential at the common output terminal of the power supply circuit.

[0023] The method may further comprise the following steps: diagnosing the presence of a fault in the second power supply branch if the measured potential at the common output terminal of the power supply circuit deviates from the third predetermined value, the second predetermined threshold value and / or if the potential at the common output terminal of the power supply circuit matches the fourth predetermined value within the second predetermined tolerance; and outputting a fault signal and / or setting a fault flag in response to diagnosing the fault in the second power supply branch. Therefore, it is equivalent whether the potential deviates from the third predetermined value or whether the potential matches the fourth predetermined value different from the third predetermined value. For example, a fault can be diagnosed if the potential deviates from 12V by at least 0.5V or if it matches 0V within a tolerance of 1V.

[0024] The diagnostic step allows testing whether the active (i.e. switched on) supply branch correctly provides power and voltage to the common output of the supply circuit. If this is the case, the expected potential at the common output matches the nominal supply voltage, e.g. 12 V. If this is not the case, the voltage is below the nominal voltage and a fault is diagnosed. By changing the roles of the first and second supply branches, the other (first) supply branch can be diagnosed in a similar manner.

[0025] The method can be performed for a power supply circuit as described herein comprising more than two power supply branches. In this case, one of the branches is switched on, while the other branches are switched off.

[0026] Another aspect of the invention relates to a computer program comprising instructions which, when executed by a computer, cause the computer to carry out a method as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the following detailed description possible embodiments of the invention are described in more detail with reference to the following drawings:

[0028] Figure 1 Exemplary embodiments of the present invention are shown. DETAILED DESCRIPTION

[0029] For the sake of brevity, only a few embodiments will be described below. Those skilled in the art will recognize that the features described with reference to these specific embodiments can be modified and combined in different ways, and individual features can also be omitted. The general descriptions in the above sections also apply to the more detailed descriptions below.

[0030] Figure 1 An exemplary embodiment of the present invention is illustrated by a power supply circuit 1 comprising a first power supply branch 2a and a second power supply branch 2b connected in parallel. The power supply circuit 1 is therefore a redundant power supply circuit. Both branches 2a and 2b are connected to a common output terminal 3 of the power supply circuit 1. The load ( Figure 1 (not shown) such as motors, sensors, control units, rear lights or headlights, etc. can be connected to the common output terminal 3. Figure 1 In the exemplary embodiment of the present invention, the power supply circuit 1 comprises two parallel branches, but the present invention is not limited to two branches, and more branches usually increase the robustness and fault safety of the circuit.

[0031] exist Figure 1 In the example of FIG. 1 , each power supply branch 2a, 2b includes a first semiconductor switch 3a and 3b, respectively, and the first semiconductor switch 3a and 3b include an input terminal and an output terminal. The input terminal can be connected to a power supply ( Figure 1 3a and 3b). Thus, the semiconductor switches 3a and 3b allow the corresponding branches 2a and 2b to be connected to or disconnected from the power supply. Each power supply provides a voltage (e.g. 12V, 24V, 48V, etc.) and a current depending on the load connected to the common output terminal 3 of the power supply circuit 1. For redundancy reasons, the power supplies of the first branch 2a and the second branch 2b should be different. In particular, for reasons of increased fail-safety, it is preferred that the power supplies are independent and / or undisturbed. The electrical connection to the power supply can be achieved by a plug connection, a clamp, a solder connection, etc.

[0032] The semiconductor switches 3a and 3b may be or include MOSFETs. In addition, the semiconductor switches 3a and 3b may include high-side drivers so that the switches 3a, 3b may be controlled by a voltage level lower than the voltage actually switched by the switches 3a, 3b. For example, the high-side drivers may allow the switches 3a, 3b to be controlled by voltage levels in transistor-transistor logic (TTL) or complementary metal oxide semiconductor (CMOS) logic. Thus, the operation of the switches 3a, 3b may be controlled, for example, by a microcontroller ( Figure 1 (not shown) control.

[0033] Furthermore, the semiconductor switches 3a, 3b may include overcurrent protection that shuts down the switch in the event of overcurrent or overheating. For example, electronic fuses (e-fuses) may be provided as overcurrent protection. These are integrated circuits that replace larger conventional fuses or other protection devices.

[0034] exist Figure 1 In the example of FIG. 1 , each branch 2a, 2b of the power supply circuit 1 further comprises a second semiconductor switch 4a and 4b, respectively. The second switch operates in the opposite direction compared to the first switch. Figure 1 In the example of FIG. 4 , the first semiconductor switches 3 a, 3 b are operated in reverse direction and the second semiconductor switches 4 a, 4 b are operated in forward direction. The reverse and forward directions are defined with respect to the body diodes formed in the semiconductor switches.

[0035] Just like the first semiconductor switches 3a, 3b, the second semiconductor switches 4a and 4b may be or include MOSFETs. In addition, the semiconductor switches 4a and 4b may include a high-side driver so that the switches 4a, 4b may be controlled by a voltage level lower than the voltage actually switched by the switches 4a, 4b. For example, the high-side driver may allow the switches 4a, 4b to be controlled by a voltage level in transistor-transistor logic (TTL) or complementary metal oxide semiconductor (CMOS) logic. Thus, the operation of the switches 4a, 4b may be controlled, for example, by a microcontroller ( Figure 1 The use of semiconductor switches 4a and 4b at the output of the supply branches 2a and 2b is advantageous because these switches can provide a low on-resistance (R DS(on) ), which is required, for example, in automotive applications to power high power external loads such as taillights or headlights.

[0036] Figure 1 Each power supply branch 2a, 2b in the example of FIG. 1 further comprises a first resistor 5a and 5b, respectively. The first end of the first resistor 5a, 5b is electrically connected to the electrical connection of the first semiconductor switch 3a, 3b and the second semiconductor switch 4a, 4b, respectively. The second end of the first resistor 5a, 5b is configured to be electrically connected to the reference potential. Figure 1In the example case, the reference potential is ground. The electrical connection to the reference potential can be achieved by a plug connection, a clamp, a solder connection, etc. In addition, the connection to ground can be disconnected by another semiconductor switch (not shown in the figure) to prevent current from flowing in the power safety mode, thereby reducing the quiescent current. The power safety mode can be a non-safety critical mode.

[0037] The first resistors 5a and 5b may have an exemplary value of 10 kΩ, although other values ​​may be used depending on the application. Furthermore, the values ​​of the resistors 5a and 5b are typically the same, but this is not required.

[0038] During nominal operation of the power supply circuit 1, one power supply branch (e.g. 2a) is always active, while the other branch (e.g. 2b) is disconnected. To this end, the first semiconductor switch 3a and the second semiconductor switch 4a in the first branch 2a are turned on, and the first semiconductor switch 3b and the second semiconductor switch 4b in the second branch 2b are turned off. If the power supply supplying the active branch 2a loses power, the controller etc. ( Figure 1 The first branch 2a can be deactivated and the second branch 2b activated (not shown). The power loss can be sensed at the common output 3 of the power supply circuit 1: During normal operation, a nominal voltage (e.g. 12V in the example) should be present at the output 3. In the event of a power outage, the voltage can drop significantly.

[0039] exist Figure 1 In the example of , the power supply circuit 1 further comprises optional second resistors 6a and 6b between the connection of the first semiconductor switch and the second semiconductor switch and the common output terminal 3 of the power supply circuit 1. Thus, the first resistors 5a, 5b and the second resistors 6a, 6b form a voltage divider. In other embodiments, the second resistors 6a and 6b are not present.

[0040] Regardless of the presence or absence of the optional second resistor 6a, 6b, the output of the semiconductor switch 3a, 3b is pulled to a defined potential even if the corresponding switch is open, for example in a non-conducting state. Figure 1 As shown, this is caused by the first resistors 5a, 5b being connected to ground. Based on this, a self-test of the power supply circuit 1 can be performed to meet certain safety goals, as described below.

[0041] In order to ensure no interference between the two supply branches 2a and 2b according to Automotive Safety Integrity Level (ASIL) D, the following safety goals (SG) should be met:

[0042] SG 1a: Avoid passing through both branches 2a and 2b simultaneously for a duration of t short The overcurrent I max_KL30_x_short (Hard short circuit).

[0043] SG 1b: Avoid passing through both branches 2a and 2b simultaneously for a duration of t long The overcurrent I max_long_KL30_x_long (soft short circuit).

[0044] SG 2a: Avoid entering the corresponding branches 2a and 2b for a duration of t short The reverse current I revmax_KL30_x_short .

[0045] SG 2b: The duration of the branch to be avoided is t long The reverse current I revmax_KL30_x_long .

[0046] SG 3: Improve availability of common output 3 (this target is typically lower than ASIL-D, but can be as high as ASIL-D).

[0047] t short An exemplary value is 500 μs, t long An exemplary value for is 100ms. These values ​​generally depend on the application. For current values ​​I max_KL30_x_short ,I max_long_KL30_x_long ,I revmax_KL30_x_short and I revmax_KL30_x_long The same is true.

[0048] In order to achieve the above safety goals, the following self-tests must be followed to diagnose and mitigate faulty components or similar fault situations. For this purpose, it is assumed during the diagnosis that the power supplies feeding the respective supply branches 2a and 2b are respectively approximately nominal battery voltages U batt Similar voltage U a and U b For example, two voltage supplies can provide about 12V, that is, U a ≈U b And U batt =12V. Therefore, the voltage U at the common output terminal 3 of the power supply circuit 1 is O It will also be approximately 12V.

[0049] The table below shows a test for a drain-to-source short circuit of semiconductor switches 3a, 3b, 4a and 4b in two supply branches 2a and 2b. Of course, the test can be performed if more supply branches are present and the switches are operated accordingly.

[0050]

[0051] This shows that Figure 1 In the example of FIG. 1 , the expected potential U at points MP1 and MP2 in the absence of a fault (“pass”) and in the presence of a fault (“fail”) is shown by means of the states of the individual switches controlled by their gates (see Figure 1 ), and the failure mode (“diagnostic mode”) that should be detected by the respective test case. It should be mentioned that 0V and U batt The expected potential depends on the actual nominal voltage and whether there are optional resistors 6a and 6b. In addition, the expected potential may depend on the resistance value of the resistor. Therefore, in other embodiments, the expected potential may be different and the fail / pass criteria may also be different.

[0052] The potentials at the test or measurement points MP1 and MP2 can be measured, for example, by means of an analog-to-digital converter (ADC), and a digital representation of the measured potentials can be fed to a microcontroller which performs and monitors the self-test.

[0053] If a fault is detected during the above test, all switches 3a, 3b, 4a and 4b shall be closed to meet safety goals SG 2a and SG 2b. The controller controlling the test shall detect and report the fault. Safety goal SG 3 has a lower priority and will be violated.

[0054] With the help of the following table, the test for a proper off-state (ie high drain-source impedance at the off-gate) of switches 3a, 3b, 4a and 4b is described:

[0055]

[0056] This shows that Figure 1 In the example of FIG. 1 , the state of each switch controlled by its gate is used to generate a signal at the common output terminal 3 (see FIG. 1 ) in the absence of a fault (“pass”) and in the presence of a fault (“fail”). Figure 1 ) and the failure mode (“diagnostic mode”) that should be detected by the respective test case.

[0057] The potential at the test or measurement point MP3 can be measured, for example, by means of an analog-to-digital converter (ADC), and a digital representation of the measured potential can be fed to a microcontroller which performs and monitors the self-test.

[0058] Only when the corresponding output voltage at the common output terminal 3 corresponds to the nominal voltage U batt, that is, the voltage supplied by the power supply at the input of the power supply circuit 1 (for example 12V), the test result should be considered "valid". The open circuit mode test of the active power supply branch should always be performed. In the case of an exemplary automotive application of the power supply circuit according to the present invention, the open circuit mode test of the other power supply branch should be performed in each ignition cycle by switching to another power supply branch that is inactive during normal operation. If necessary, the test can also be repeated during operation. The duration of checking the corresponding voltage rail should not exceed the fault tolerance time interval (FTTI), that is, if the failure mode of the other power supply branch is "open circuit", the test needs to be completed within the FTTI. Open circuit mode test and short circuit mode test can be performed simultaneously.

[0059] If a drain-to-source open circuit fault is detected, the fault should be detected and reported by the controller doing the test. In addition, if the open circuit fault is in the currently active supply branch, a switch to the inactive supply branch may be made. Although SG 3 is violated in this case, it generally has a lower priority.

[0060] In the event of a detected fault, additional measures may be taken. For example, a microcontroller controlling the self-test may set a test flag in the event of a fault. The flag may indicate to which test case the fault belongs. In the case of a power supply circuit 1 being arranged in a vehicle, starting or restarting the vehicle may sometimes be prohibited. Restarting may be prohibited after the current drive cycle has ended.

[0061] As described above, safety goals SG 2a and SG 2b are met by not turning on switches 3a and 4a simultaneously with switches 3b and 4b, i.e., only one of the power supply branches 2a and 2b is active, in combination with the above-mentioned self-test and safe state operation. Semiconductor switches 3a and 3b meet safety goals SG 1a and SG 1b as follows: Assume that the fault is a short to ground on the load side of the power supply circuit 1, for example due to a defective electronic component on the attached load side. In this case, a potential overcurrent (e.g., in one example, in a more specific example 20-25A, higher than 3A) can be detected by semiconductor switches 3a and 3b. To this end, and as described above, switches 3a, 3b may include a high-side driver with overcurrent protection, such as an electronic fuse. In the event of an overcurrent, switches 3a, 3b may be disconnected within a predetermined time, for example within 100 μs or less. As an additional safety measure, switches 3a and 3b may be of different types, for example to ensure freedom from interference (FFI) in ASIL-D.

[0062] The self-test of the power supply circuit 1 described above can be performed by a control unit such as a microcontroller. To this end, the method for diagnosing the power supply circuit 1 as disclosed herein can be implemented in hardware or software, or can be implemented partially in hardware and partially in software. Hardware suitable for implementing the method and apparatus according to the present invention includes a central processing unit (CPU), a microcontroller, an application-specific integrated circuit (ASIC), etc. (All or part of) software implementation can include compiling source code to obtain machine-readable instructions, which, when executed, cause a computer, CPU, microcontroller, etc. to perform all or part of the method steps described herein.

Claims

1. A power supply circuit (1) comprising at least two power supply branches (2a, 2b), wherein: Each power supply branch (2a, 2b) comprises: a first semiconductor switch (3a, 3b) configured to be electrically connected to a power source; a second semiconductor switch (4a, 4b) which is connected in series with the first semiconductor switch (3a, 3b) and is electrically connected to a common output terminal (3) of the power supply circuit (1); and A first resistor (5a, 5b), wherein a first end of the first resistor (5a, 5b) is electrically connected to an electrical connection between the first semiconductor switch (3a, 3b) and the second semiconductor switch (4a, 4b), and a second end of the first resistor (5a, 5b) is configured to be electrically connected to a reference potential.

2. The power supply circuit (1) according to claim 1, wherein: Each supply branch (2a, 2b) further comprises a second resistor (6a, 6b), a first end of which is electrically connected to the electrical connection between the first semiconductor switch (3a, 3b) and the second semiconductor switch (4a, 4b), and a second end of which is electrically connected to the common output terminal (3) of the supply circuit (1) so as to form a voltage divider with the first resistor (5a, 5b).

3. The power supply circuit (1) according to claim 1 or 2, wherein: The first semiconductor switch (3a, 3b) and the second semiconductor switch (4a, 4b) are MOSFETs.

4. The power supply circuit (1) according to any one of claims 1 to 3, wherein: The first semiconductor switch (3a, 3b) and / or the second semiconductor switch (4a, 4b) comprises overcurrent protection.

5. The power supply circuit (1) according to any one of claims 2 to 4, further comprising a controller, wherein the controller is configured to: Switching the semiconductor switches (3a, 3b, 4a, 4b); receiving an electrical signal corresponding to the potential (MP1, MP2) at the first end of the first resistor (5a, 5b), and / or An electrical signal corresponding to the potential (MP3) at the common output terminal (3) of the power supply circuit (1) is received.

6. The power supply circuit (1) according to claim 5, further comprising a measuring unit, the measuring unit being configured to measure the potential (MP1, MP2) at the first end of the first resistor (5a, 5b) and / or the potential (MP3) at the common output terminal (3) of the power supply circuit (1), wherein: The measuring unit is electrically connected to the controller.

7. The power supply circuit (1) according to claim 5 or 6, wherein: The controller is configured to output a fault signal and / or set a fault flag if the potential (MP1, MP2) at the first end of the first resistor (5a, 5b) deviates from a first predetermined value by a first predetermined amount and / or if the potential (MP3) at the common output terminal (3) of the power supply circuit (1) deviates from a second predetermined value by a second predetermined amount.

8. The power supply circuit (1) according to any one of claims 1 to 7, wherein: The first semiconductor switch (3a, 3b) and the second semiconductor switch (4a, 4b) include a forward direction and an opposite reverse direction, wherein the forward direction of the first semiconductor switch (3a, 3b) is configured to be operated in the reverse direction, and the second semiconductor switch (4a, 4b) is configured to be operated in the forward direction.

9. The power supply circuit (1) according to any one of claims 1 to 8, comprising two power supply branches (2a, 2b).

10. The power supply circuit (1) according to any one of claims 1 to 9, being configured for automotive applications.

11. A method for diagnosing a power supply circuit (1) according to any one of claims 1 to 10, wherein: The power supply circuit (1) comprises at least two power supply branches (2a, 2b), and wherein the method comprises the following steps: Disconnecting the first semiconductor switch (3a) and the second semiconductor switch (4a) in the first power supply branch (2a); turning on the first semiconductor switch (3b) and the second semiconductor switch (4b) in the second power supply branch (2b); and The potential (MP2) at the first end of the first resistor (5a) in the first supply branch (2a) is measured.

12. The method according to claim 11, further comprising the steps of: diagnosing the presence of a fault in the first supply branch (2a) if the measured potential (MP1) at the first end of the first resistor (5a) deviates from a first predetermined value by a first predetermined threshold value and / or if the potential (MP1) at the first end of the first resistor (5a) matches a second predetermined value within a first predetermined tolerance; as well as All semiconductor switches (3a, 3b, 4a, 4b) are opened in response to diagnosing a fault in the first supply branch (2a).

13. The method according to claim 11 or 12, further comprising the following steps: The potential (MP3) at the common output terminal (3) of the power supply circuit (1) is measured.

14. The method according to claim 13, further comprising the steps of: Diagnosing the presence of a fault in the second supply branch (2b) if the measured potential at the common output terminal of the supply circuit (1) deviates from a third predetermined value by a second predetermined threshold value and / or if the potential (MP3) at the common output terminal (3) of the supply circuit (1) matches a fourth predetermined value within a second predetermined tolerance; as well as In response to diagnosing a fault in the second power supply branch (2b), a fault signal is output and / or a fault flag is set.

15. A computer program comprising instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 11 to 14.

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