Method and control device for operating a charger for an electric vehicle, and charger

Abstract

To provide a method and control device for operating a charger for electrically driven vehicles, and a charger.SOLUTION: A charger (10) includes at least one charging terminal (11) for connecting an electrically driven vehicle, and at least one power electronics unit (12) for providing predetermined charging current and predetermined charging voltage at the charging terminal (11). When there is no vehicle connected to the charging terminal (11), the power electronics unit (12) of the charging terminal (11) is subjected to a self-test voltage corresponding to at least the maximum charging voltage of the charger (10) at predetermined time intervals over a predetermined self-test period for performing a self-test, and when formation of a short circuit or defect is ascertained, the charging terminal (11) is blocked for charging a vehicle.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for operating a bidirectional charger for DC charging of an electric vehicle, and more particularly to a control device and a charger for a bidirectional charger for DC charging of an electric vehicle. [Background technology]

[0002] The basic design of a charger for an electric vehicle is known from practice. For example, an electric vehicle charger has at least one charging terminal, which is designed to couple an electric vehicle thereto for charging said vehicle. At least one power electronics unit interacts with each charging terminal of the charger. The or each power electronics unit interacting with each charging terminal is designed to provide a predetermined charging current and a predetermined charging voltage at the respective charging terminal for charging the electric vehicle.

[0003] So-called AC charging or so-called DC charging can be used to charge electric vehicles with chargers. DC charging is used to charge the traction batteries of electric vehicles with high charging power in a short time.

[0004] Chargers for DC charging the traction battery of an electric vehicle can be in the form of a one-way charger or a bidirectional charger, where the electrical energy stored in the traction battery of the electric vehicle can be fed back into the power supply system to assist the power supply system, and such bidirectional chargers are becoming increasingly important.

[0005] In the case of bidirectional chargers for DC charging of electric vehicles, there is the problem that the electric vehicle connected to the charging terminals, i.e. its traction battery, may be damaged if a short circuit is formed in the power electronics unit interacting with the charging terminals, resulting in a breakdown of the electric vehicle and inevitably a trip to a repair shop.

[0006] In the case of bidirectional chargers for DC charging of electrically powered vehicles, the risk of damage to the connected vehicle due to a short circuit in the power electronics unit must be avoided.

[0007] DE 10 2010 042 750 A1 discloses a method and a device for identifying short circuits in a charger for an electric vehicle. To identify a short circuit, a test voltage is applied to the charging cable, which is increased in steps to a maximum voltage value. A check is made to see whether a short circuit has formed in the charging cable or in contact means connected to the charging cable.

[0008] Further chargers for DC charging of electric vehicles are disclosed in DE 10 2019 130 421 A1 and DE 10 2019 117 375 A1. For example, in the charger disclosed in DE 10 2019 130 421 A1, the insulation monitoring device has at least two electrical measuring resistors, each of which is connected to one charging line. Before each charging operation, an insulation test is performed by the insulation monitoring device, for example by bus shifting, in both asymmetric and symmetric test modes.

[0009] WO 2022 / 008 640 A1 brochure (Patent Document 4) discloses another charger for electric vehicles.

[0010] WO 2015 / 036 063 A1 (Patent Document 5) discloses an electrically powered vehicle having an insulation monitoring function for a high-voltage vehicle power supply system.

[0011] There is a need for a method of operating a bidirectional charger for DC charging of electric vehicles and a control device for carrying out said method, which makes it possible to prevent the risk of damage to a vehicle connected for charging as a result of a short circuit in the power electronics unit of the charger, and also for a corresponding charger. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] DE 10 2010 042 750 A1 [Patent Document 2] German Patent Application Publication No. 10 2019 130 421 A1 [Patent Document 3] German Patent Application Publication No. 10 2019 117 375 A1 [Patent Document 4] International Publication No. 2022 / 008 640 A1 Brochure [Patent Document 5] International Publication No. 2015 / 036 063 A1 Brochure Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention is therefore based on the object of providing a novel method and control device for operating a bidirectional charger for DC charging of electric drive vehicles and a corresponding charger. [Means for solving the problem]

[0014] This object is achieved by a method for operating a bidirectional charger for DC charging of electric vehicles as set forth in patent claim 1. According to the invention, in order to perform a self-test when no vehicle is connected to the respective charging terminal, a self-test voltage corresponding to at least the maximum charging voltage of the charger is applied to the respective power electronics unit of the respective charging terminal at predetermined time intervals for a predetermined self-test period, in which a check is then made to see whether a short circuit or defect has been formed in the respective power electronics unit of the respective charging terminal, and if it is determined that no short circuit or defect has been formed, the respective charging terminal is enabled to charge the vehicle, and if it is determined that a short circuit or defect has been formed, the respective charging terminal is blocked from charging the vehicle.

[0015] The invention proposes to carry out a self-test at predefined time intervals over a predefined self-test period, which tests the respective power electronics unit with a self-test voltage that at least corresponds to the maximum charging voltage of the charger. This self-test voltage is therefore applied to the respective power electronics unit at predefined time intervals and for a predefined self-test period, i.e. when a vehicle is not connected to a charging terminal that interacts with the respective power electronics unit for charging. The presence of the self-test voltage leads to a short circuit being formed in said semiconductor module, in particular when a semiconductor module of the power electronics unit is in a faulty state, which short circuit can be detected. If a short circuit is formed in the respective power electronics unit, the respective charging terminal is blocked from charging the vehicle. Only if no short circuit is formed in the power electronics unit during the self-test is the respective charging terminal allowed to subsequently charge the vehicle. There is then no risk of the electric drive vehicle, i.e. its traction battery, being damaged during charging by a short circuit in the power electronics unit of the charger.

[0016] Preferably, to perform the self-test, a self-test voltage is applied to each power electronics unit which is greater than the maximum charging voltage of the charger, which is particularly preferred for performing the respective power electronics unit of the charger in a reliable manner.

[0017] Preferably, the self-test of each power electronics unit is terminated if a vehicle is connected to the respective charging terminal while the self-test is being performed. The self-test is terminated if a vehicle is connected to the charging terminal where the respective power electronics unit is undergoing a self-test. This eliminates the risk that the traction battery of the electric drive vehicle will be damaged as a result of the self-test. In addition, charging at the desired voltage is possible.

[0018] Preferably, to perform the self-test, at least the following steps are performed: checking the state of the respective power electronics unit, where the self-test routine is started only if the power electronics unit is not in a fault state or is not in a charging state. After the self-test routine has started, a check is made to see if a self-test is currently being performed on the respective power electronics unit. If a self-test is not currently being performed on the respective power electronics unit, a check is made to see if the period since the last self-test has reached or exceeded a predefined time interval between self-tests. If it is determined that the period since the last self-test has reached or exceeded a predefined time interval between self-tests, a check is made to see if the respective power electronics unit is in a sleep state or in an operational state. If it is determined that the respective power electronics unit is in an operational state, a self-test is started. If it is determined that the respective power electronics unit is in a sleep state, the respective power electronics unit is woken up and moved to an operational state. This procedure is preferred to check if a self-test routine should be started. If the respective power electronics unit which is to perform the respective self-test is in a sleep mode, the power electronics unit is woken up for the self-test.

[0019] Preferably, during execution of the self-test, a check is made to determine whether a vehicle is connected to the respective charging terminals, and if it is determined that a vehicle is connected to the respective charging terminals, the self-test is terminated or a predetermined charging voltage is provided at the respective charging terminals.

[0020] Preferably, during execution of the self-test, a check is made to see if a predetermined self-test period from the start of the self-test has been reached or exceeded. If it is determined that the predetermined self-test period has been reached or exceeded, the self-test is terminated.

[0021] When the self-test routine is started, first the maximum self-test duration or its execution duration is monitored, and then during the execution of the self-test routine, and thus the self-test, a check is made to see if the vehicle is connected to the charging terminals that interact with the power electronics unit under test. If the vehicle is connected to the charging terminals, the self-test is terminated. If a predetermined self-test time for executing the self-test is reached or exceeded, the self-test and thus the self-test routine is terminated.

[0022] The control device for a charger for an electric vehicle according to the invention is defined in patent claim 9 and the charger is defined in claim 10.

[0023] Preferred developments of the invention can be inferred from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being in any way limited to these exemplary embodiments. In the drawings: [Brief description of the drawings]

[0024] [Figure 1] 1 shows a block circuit diagram of a first charger for an electric drive vehicle. [Diagram 2] 1 shows a block circuit diagram of a second charger for an electric drive vehicle. [Diagram 3] 3 shows a signal flow chart illustrating a method of operation of a charger for an electric vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] 1 shows in highly schematic form a bidirectional charger 10 for DC charging of electric vehicles. Charger 10 has charging terminals 11 for connecting an electric vehicle to be charged.

[0026] Additionally, the charging station 10 comprises a power electronics unit which interacts with the charging terminals 11. The power electronics unit 12 includes, for example, an AC / DC converter, a DC / DC converter and semiconductor modules. The power electronics unit 12 is connected to a power supply system 13.

[0027] With the bidirectional charger 10, electrical energy drawn from the power supply system 13 can be stored in the traction battery of an electric vehicle. Similarly, electrical energy stored in the traction battery can be fed back to the power supply system 13 to supplement it.

[0028] 2 shows in very schematic form a charger 10 with two charging terminals 11. In each case, an electric vehicle can be connected to each charging terminal 11. A power electronics unit 12 interacts with each charging terminal 11, and in turn a link with a power supply system 13 is made via said power electronics unit 12.

[0029] In order to increase the charging power available at one of the charging terminals 11 of the charger 10 shown in FIG. 2, the two power electronics units 12 can be interconnected via a switch 14, in which case only one of the charging terminals 11 is used to charge the electric vehicle with the increased charging power.

[0030] The present invention relates herein to a method of operation of a bidirectional charger 10 for DC charging of an electric drive vehicle and a control device therefor, the charger 10 having at least one charging terminal 11 for connecting an electric drive vehicle and at least one power electronics unit 12 for providing a predetermined charging current and a predetermined charging voltage for DC charging at each charging terminal 11.

[0031] To perform a self-test of each power electronics unit 12 of each charging terminal 11, a self-test voltage corresponding to at least the maximum charging voltage of the charger 10 is applied to each power electronics unit 12 of each charging terminal 11 at predetermined time intervals, in particular every hour or two hours, for a predetermined self-test period, in particular 1 minute, 2 minutes or 3 minutes.

[0032] In this case, a check is made to see whether a short circuit has formed in the respective power electronics unit 12 of the respective charging terminal 11, in particular in the semiconductor module of the respective power electronics unit 12. This can be done, for example, via a current measurement, a voltage measurement, etc.

[0033] If it is determined that no short circuit is present in the respective power electronics unit 12, the respective charging terminal 11 is enabled to charge the electric vehicle.

[0034] On the other hand, if it is determined that a short circuit has occurred in the respective power electronics unit 12, the respective charging terminal 11 is blocked from charging the electric vehicle.

[0035] In this case, the self-test is only carried out when the vehicle is not connected for a charging operation to the respective charging terminal 11 for which the self-test is to be carried out for its power electronics unit 12 .

[0036] Preferably, the self-test voltage applied to each power electronics unit 12 for performing the respective self-test is greater than the maximum charging voltage of the charging station 10. In particular, it is provided that the self-test voltage is at least 50 V higher, preferably at least 75 V, particularly preferably at least 100 V higher than the maximum charging voltage of the charging station 10.

[0037] During execution of the self-test, when the vehicle is connected to the charging terminals of each of the power electronics units 12 being tested, the self-test of each of the power electronics units 12 is terminated.

[0038] Within the meaning of the invention described herein, it is therefore proposed to apply to each power electronics unit 12 of a bidirectional charger 10 for DC charging of electric drive vehicles a self-test voltage which at least corresponds to the maximum charging voltage of the charger, and preferably is higher than this charging voltage, at predetermined time intervals and for a predetermined self-test period.

[0039] In particular if a semiconductor module of the respective power electronic unit 12 is in a faulty state, in which case a short circuit is formed in said semiconductor module during the self-test, which can be monitored in a conventional manner, for example via a current measurement, via a voltage measurement or via an insulation monitoring device.

[0040] If a short circuit is established in the power electronics unit 12, the charging terminals 11 interacting with the power electronics unit 12 are blocked from charging. Only if no short circuit is established in the power electronics unit 12 during the execution of the self-test, the charging terminals interacting with the power electronics unit are enabled to charge the vehicle.

[0041] Further details of the present invention will now be explained with reference to the signal flow chart of FIG.

[0042] To perform a self-test on each power electronic unit, first in block 20 the state of the respective power electronic unit 12 to be tested is checked, or more precisely in block 20 the state of the power electronic unit is queried.

[0043] In this case, each power electronics unit 12 can be or have a fault state according to block 21 , a charging state according to block 22 or a chargeable state according to block 23 .

[0044] The self-test routine is not started if the respective power electronics unit 12 has a fault state, block 21, a charging state, block 22. On the other hand, the self-test routine is started only if, in block 20, it is determined that the respective power electronics unit 12 has or assumes the chargeable state, block 23. If a fault state exists, a corresponding error code is generated in block 36 and transmitted, for example, to a display of the charging station 10.

[0045] After the self-test routine has begun, a check is made in block 24 to see if a self-test is currently being performed on the respective power electronics unit 12. If block 24 determines that a self-test routine is not currently being performed on a power electronics unit 12 that was previously determined to be in a chargeable state, block 24 branches to block 25.

[0046] In block 25 a check is made to see whether the period since the last self-test has reached or exceeded a predetermined interval between two self-tests, in particular a period of one or two hours.

[0047] If it is determined in block 25 that the time since the last self-test has reached or exceeded the predetermined interval between two successive self-tests, then in block 26 a check is made to see if the respective power electronics unit is in a sleep state or an operational state. If it is determined in block 26 that the respective power electronics unit is in a sleep state, then block 26 branches to block 27. In block 27, the respective power electronics unit 12 is woken up and transitioned to an operational state.

[0048] On the other hand, if block 26 determines that the respective power electronics unit is operational and not asleep, then a branch is made to block 28 where a self-test is initiated.

[0049] If in block 24 it is determined that a self-test has currently been performed on the respective power electronics unit 12, then block 24 branches to block 29. In block 29 a check is made to see if the vehicle is connected or is connected to a charging terminal 11 that interacts with the respective power electronics unit 12.

[0050] If in block 29 it is determined that a vehicle is connected or is connected to the respective charging terminal 11, then block 29 branches to block 30 where the voltage provided by each power electronics unit 12 is limited to a maximum charging voltage, after which the self-test is ended or terminated in block 31.

[0051] On the other hand, if block 29 determines that there is no vehicle connected or attached to a charging terminal that interacts with the power electronics unit 12, block 29 branches to block 32, where a self-test voltage higher than the maximum charging voltage of the charger 10 is applied to the power electronics unit 12.

[0052] After block 32, during the execution of the self-test, a check is made to see whether a predefined self-test period for the self-test has been reached or exceeded. If it is determined that this is the case, i.e. that the predefined self-test period for the self-test has been reached or exceeded, a branch is made from block 33 to block 34, where the voltage at the power electronics unit 12 is again limited to the maximum charging voltage of the charger. Then, in block 35, the self-test is terminated.

[0053] Thus, as explained with reference to FIG. 3, first in block 20 the state of the power electronics unit to be tested is checked or queried. If the power electronics unit 12 is in a fault state in block 21 or in a charging state in block 22, nothing is done. In block 36 only a corresponding error code is generated and transmitted. If it is determined in block 20 that the power electronics unit 12 is in a charging state in block 23, a check is made in block 24 to see whether a self-test is currently being performed. If this is not the case, a check is made in block 25 to see whether a predefined time interval between two self-tests has been reached or exceeded since the last self-test was performed. If this is the case, then in block 27 the power electronics unit is woken up if it is in a sleeping state, or in block 28 a self-test is started if it is not in a sleeping state. If after blocks 27 and 28 it is determined in block 25 that a predefined time interval between two self-tests has not been reached or exceeded since the last self-test was performed, the method visualized in FIG. 3 starts from the beginning. If it is determined in block 24 that a self-test is currently being performed on the power electronics unit 12, then in block 29 a check is made to see whether a vehicle has been or is connected to the respective charging terminal 11. If this is the case, then a branch is made from block 29 to block 30 and then to block 31, whereupon the self-test is terminated and the voltage at the charging terminal 11 is limited to the maximum charging voltage. The charging voltage required for charging is provided at the charging terminal 11 and the method of FIG. 3 starts over. On the other hand, if it is determined in block 29 that no vehicle is connected to the corresponding charging terminal 11, then in block 32 a self-test voltage higher than the maximum charging voltage is applied to the power electronics unit. In this case, then in block 33 a check is made continuously to see whether a predetermined self-test period for the self-test has been reached or exceeded.If the predetermined self-test period for the self-test has been exceeded, the self-test is terminated in blocks 34, 35 and the method starts again from the beginning.

[0054] The invention further relates to a control device for a bidirectional charger 10 for DC charging of electric vehicles, which is designed to automatically carry out the above-mentioned method on the control side.

[0055] Additionally, the present invention relates to a charger including such a control device. [Explanation of symbols]

[0056] 10 charger 11 Charging terminal 12 Power Electronics Unit 13 Power Supply System 14 Switch 20 blocks 21 Block 22 Blocks 23 Block 24 blocks 25 blocks 26 Blocks 27 Blocks 28 blocks 29 Blocks 30 blocks 31 Block 32 blocks 33 Block 34 Blocks 35 blocks 36 Blocks

Claims

1. A method of operating a bidirectional charger (10) for DC charging of electric vehicles, the charger (10) having at least one charging terminal (11) for connecting an electric vehicle and at least one power electronics unit (12) for providing a predetermined charging current and a predetermined charging voltage at each of the charging terminals (11), wherein when no vehicle is connected to each of the charging terminals (11), a self-test voltage corresponding to at least a maximum charging voltage of the charger (10) is applied to each of the power electronics units (12) of each of the charging terminals (11) at predetermined intervals and for a predetermined self-test period in order to perform a self-test, wherein a check is made to see whether a short circuit or a defect has been formed at each of the power electronics units (12) of each of the charging terminals (11), and if it is determined that no short circuit or defect has been formed, each of the charging terminals (11) is enabled to charge the vehicle, and if it is determined that a short circuit or defect has been formed, each of the charging terminals (11) is blocked from charging the vehicle, A self-test voltage higher than a maximum charging voltage of the charger (10) is applied to each of the power electronics units (12) to perform the self-test.

2. 2. The method according to claim 1, characterized in that the self-test voltage is at least 50 volts higher, preferably at least 75 volts higher, particularly preferably at least 100 volts higher than the maximum charging voltage of the charger (10).

3. 2. The method according to claim 1, characterized in that the self-test of each of the power electronic units (12) is terminated if a vehicle is connected to the respective charging terminal (11) during the execution of the self-test.

4. To perform the self-test, at least checking the status of each said power electronics unit (12), where a self-test routine is initiated only when said power electronics unit is neither in a fault state nor in a charging state; after a self-test routine has started, checking whether a self-test is currently being performed on each of said power electronic units; if a self-test has not currently been performed on each of said power electronic units, checking whether the time since the last self-test has reached or exceeded a predefined time interval between self-tests; if it is determined that the time since a last self-test has reached or exceeded the predetermined time interval between self-tests, checking whether each of the power electronics units is in a sleep state or an operational state; initiating a self-test when each of the power electronics units is determined to be operational; 2. The method of claim 1, wherein:

5. 5. The method according to claim 4, characterized in that if it is determined that the respective power electronics unit is in a sleep state, the respective power electronics unit is woken up and transitioned to an operational state.

6. checking whether a vehicle is connected to each of said charging terminals when a self-test is performed; if it is determined that a vehicle is connected to each of the charging terminals, terminating the self-test and providing the predetermined charging voltage to each of the charging terminals (11); The method according to claim 4, characterized in that

7. when a self-test is performed, checking whether the predetermined self-test period for the self-test from the start of the self-test has been reached or exceeded; terminating the self-test when it is determined that the predetermined self-test period has been reached or exceeded; The method according to claim 4, characterized in that

8. A control device for a bidirectional charger (10) for DC charging of electric drive vehicles, the control device being designed to automatically carry out the method according to any one of claims 1 to 7.

9. A charger for bidirectional charging of an electric drive vehicle, the charger comprising the control device of claim 8.

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