Method and device for charging process of energy source of power-off drive

Abstract

The invention relates to a method (500) for interrupting a charging process of an energy source (230) of a power-off drive (200), comprising the steps of: detecting (510) a fault at a high-side switch (231, 233, 235) of a first half-bridge of an inverter (210); a low side switch (232, 234, 236) of a half-bridge of the inverter (210) is closed (520).

Description

Technical Field

[0001] The invention relates to a method and a device for interrupting a charging process of an energy source of an electric drive, a drive train having the device, a vehicle having the drive train, and a computer program and a computer-readable storage medium. Background Art

[0002] In the effort to develop more environmentally friendly methods of mobility, electric vehicles are an important component. However, in order for electric vehicles to gain widespread acceptance, a number of prerequisites must be met. In addition to a sufficient range of the vehicle, a wide range of energy supplies is also required in order to ensure that the electric vehicle can be charged at any time. Furthermore, the required charging time must be kept short in order to avoid long delays.

[0003] When charging an electric vehicle at an alternating current (AC-) charging station, for example when connected to a public power grid, the alternating current voltage is converted into a direct current voltage (DC) by a rectifier preferably in the vehicle. Fast charging stations are becoming increasingly popular, and the fast charging stations directly provide a direct current voltage and are characterized by shorter charging times. An exemplary direct current fast charging station is known from WO 2012 / 038222 A3. An inverter is known from WO 2019 / 215128A1, which is used to convert the electrical energy of a direct current voltage source into an alternating current voltage for driving an electric motor. In addition, the inverter is set to increase the charging voltage of the charging device to a higher voltage. If the available charging voltage is less than the required voltage for charging the vehicle battery, then this type of boost chopper is used. The corresponding inverter includes switches or relays, which can realize charging operation in a closed state and thus can realize the flow of current from the charging device through the windings of the motor via the inverter controlled as a boost chopper to the connected battery. Interference may occur during the charging operation, which must be eliminated. A critical fault for the system is the failure or continuous closure of the upper power switch of the inverter half-bridge. The higher voltage of the vehicle battery to be charged is then continuously applied to the charger, which is only designed for lower charging voltages. This can lead to damage to the charging station. Therefore, there is a need for a solution that identifies such interference and minimizes the resulting damage. For this reason, a solution that can operate safely, reliably and quickly under the high voltages and high currents that occur here is required. Summary of the invention

[0004] The present invention realizes a method having the features of claim 1, a device having the features of claim 3, a drive system having the features of claim 4, a vehicle having the features of claim 5, a computer program having the features of claim 6 and a computer-readable storage medium having the features of claim 7.

[0005] The present invention therefore relates to a method for interrupting the charging process of an energy source of an electric drive. Preferably, the present invention relates to a method for interrupting the charging process of an energy source for or with an electric drive. The electric drive is preferably designed for operating a vehicle. The electric drive comprises an inverter and a multi-phase electric machine, wherein the inverter has a positive input connection and a negative input connection on the input side for connecting an energy source, preferably a DC voltage energy source, such as a battery or a traction battery or a fuel cell. A fuse is arranged between the positive connection of the energy source and the positive input connection of the inverter. Preferably, such a fuse is integrated with the energy source into a common housing. Preferably, the fuse is preferably implemented bidirectionally as a mechanical fuse, an electronic fuse, a hybrid fuse, a fuse, a pyrotechnic fuse and or a semiconductor switch. In a battery management system of a battery-electric vehicle, preferably such a fuse is arranged within the housing of the battery or the energy source. The energy source for a battery-electric vehicle preferably includes a corresponding fuse to prevent a short circuit between the two poles of the energy source or the energy source connection pole. Advantageously, when the short-circuit current is very large within a short time, the corresponding fuse is disconnected within a very short time. The inverter includes a multi-phase connection on the output side for connecting the phase connection of the multi-phase motor. The inverter is set to supply electric energy to the motor in the motor operation and receive the electric energy of the motor in the generator operation. The inverter includes a plurality of power switches. The power switch is arranged in a half-bridge connected in parallel as a high-side switch and a low-side switch, and the half-bridge is connected between the positive input connection and the negative input connection of the inverter. The central tap between the corresponding high-side switch and the low-side switch of the half-bridge is respectively connected to a phase of the multi-phase connection. The high-side switch and the low-side switch of the inverter are controlled in a modulated manner, preferably in a pulse width modulation manner or a square wave commutation manner in the motor or generator operation. The energy received in the generator operation is preferably transferred to the connected energy source for charging the energy source. The multi-phase motor includes a plurality of windings, preferably at least one winding per phase. Preferably, each of the phases comprises a phase connection, which is connected to the multi-phase connection of the inverter for connection to the inverter. At least one winding of the multi-phase electric machine comprises a further winding connection. The winding connection is connected to the motor connection. Preferably, the winding connection is configured as one of two connection contacts at the end of the winding. Preferably, the winding connection can also be configured between the two ends of the winding. Preferably, the winding connection is therefore connected to the phase connection of the electric machine, or is arranged between at least two windings of the winding of the multi-phase machine, or is arranged within one of the windings of the multi-phase machine. The winding connection of the electric machine is connected to the motor connection. Preferably, the motor connection is a contact connected to the winding connection. The motor connection is connected to the positive charging connection. The negative input connection is connected to the negative charging connection. Preferably, the electric drive comprises a switch connected between the motor connection and the positive charging connection.Preferably, the switch is closed during the charging operation of the vehicle and is opened during its driving operation (motor operation, generator operation). The switch is preferably designed as an electromechanical switch, that is, as a contactor or a relay. Preferably, the electric drive device includes a first capacitor, which is connected in parallel with the positive charging terminal and the negative charging terminal at least during the charging process. Preferably, the first capacitor reduces the voltage and current fluctuations at the positive and negative charging terminals formed during the switching process of the power switch of the inverter. During the charging process of the energy source, the charging energy source is connected to the positive charging terminal and the negative charging terminal. Here, electrical energy is provided by the charging energy source via the inverter for charging the energy source. Preferably, the charging energy source is a charging station or charging pile preferably in the infrastructure, which provides electrical energy for charging the energy source of the vehicle. Preferably, electrical energy is provided by means of the charging energy source for charging the energy source connected to the input terminal. Preferably, when charging the energy source, a charging current flows from the charging energy source via the positive charging connection via the motor connection through at least one winding of the electric machine and via at least one of the high-side switches of the inverter via the positive input connection into the energy source.

[0006] Connecting and disconnecting or decoupling, or connected and disconnected, are used synonymously with electrically connecting and disconnecting.

[0007] Preferably, the windings of the multiphase electric machine are connected in a star shape. In this case, the star point of the electric machine is designed as a winding connection. Preferably, the electric drive comprises an inverter and an electric machine, whose windings are connected in a star shape, wherein the star point of the electric machine is designed as a winding connection. The winding connection is connected to the motor connection. Preferably, a circuit is provided that enables a switchable charging connection for connecting a charging energy source to the electric drive via the star point of the electric machine and disconnecting the charging energy source.

[0008] The method comprises the steps of identifying a fault at the high side switch of the first half-bridge of the inverter and closing the low side switch of the half-bridge of the inverter, especially the low side switch of the first half-bridge. In this order of steps, it is first determined that there is a fault. Preferably, what is identified as a fault is that the high side switch is closed and can no longer be disconnected. In particular, a signal for disconnecting the switch is applied at the control input of the high side switch and the switch remains closed. In this fault situation, a high current flows through the switch and a minimum voltage is generated on the switch. If this state is maintained, the current direction is reversed from the charging energy source to the energy source during charging operation. An unlimited current will be generated, which flows from the energy source to the direction of the charging energy source. However, the charging energy source and the internal or connected components, such as, for example, the intermediate circuit capacitor, are not designed for the high voltage of the energy source. This will lead to the destruction of the charging energy source and other components. Therefore, it is preferred to directly and or continuously implement the second step, so as to prevent the destruction of the charging energy source. Close the low side switch of the half bridge, preferably the low side switch of the first half bridge. This results in a direct short circuit of the energy source through two power switches of the inverter when at least one winding of the motor is connected, preferably a short circuit of the energy source through two power switches of the first half-bridge of the inverter. Alternatively, two low-side switches of the low-side switches can also be closed, preferably the low-side switches of the second and third half-bridges. The rapidly formed high current also flows through the fuse. When the short circuit is achieved only by the two power switches of the first half-bridge of the inverter, the fastest current rise and therefore the fastest triggering of the fuse are achieved. The fuse then reliably, safely and very quickly disconnects the current loop and eliminates the direct risk of damage to the charging energy source.

[0009] Advantageously, a method for an electric drive is provided which prevents damage to a charging energy source during the charging process of the energy source. For this purpose, no additional circuit is required. If the fuse is an irreversible fuse, then the fuse must then preferably be replaced in a repair shop. Preferably, faults at the high-side switch in the inverter should also be eliminated. Preferably, the total damage to be eliminated is significantly less than the potential damage at the charging energy source.

[0010] In one refinement, a fault at the high-side switch is detected by means of an overcurrent protection circuit, a diagnostic method and / or at least one phase current sensor of the inverter.

[0011] A circuit assembly is used for carrying out the method, which is also used for normal operation of the electric drive. A fault at the high-side switch of the first half-bridge of the inverter is then preferably detected by means of an existing overcurrent protection circuit. The circuit is used for driving operation of the inverter or the electric drive in order to detect a high load on the power switch in the inverter and to avoid excessive loads by means of a suitable operating strategy. As an alternative or in addition, another diagnostic method is used for the detection, which is preferably also used during driving operation of the electric drive. Likewise, as an alternative or in addition, the measured value of at least one phase current sensor is taken into account for detecting the fault.

[0012] Advantageously, a method is provided for identifying a fault at a high-side switch for use during a charging process.

[0013] The invention furthermore comprises a device for interrupting a charging process of an energy source of an electric drive. The device is designed to carry out the described method. Preferably, the device comprises a control unit, which preferably has a microcontroller, a voltage supply, preferably at least one signal input for detecting a fault, and or preferably at least one signal output for closing a low-side switch. Advantageously, a device is provided, which is designed to prevent damage to the charging energy source during the charging process.

[0014] The invention further relates to a drive train having the described device, wherein the drive train comprises an inverter, a preferably multi-phase electric machine and / or an energy source. Advantageously, a drive train having a device is provided which is designed to prevent damage to the charging energy source during the charging process. This enables reliable operation of the drive train.

[0015] The invention further relates to a vehicle having such a drive train. Advantageously, a vehicle having such a device is provided, which is designed to prevent damage to a charging energy source during a charging process. This enables reliable operation of the vehicle.

[0016] The invention further relates to a computer program comprising commands which, when the program is executed by a device, cause the device to carry out the steps of the described method.

[0017] Furthermore, the invention relates to a computer-readable storage medium comprising instructions which, when executed by a device, cause the device to carry out the steps of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the figure:

[0019] Figure 1 A first schematic block diagram of an electric drive device having a device is shown;

[0020] Figure 2 A schematic diagram of a vehicle having an electric drive train with a device is shown;

[0021] Figure 3 A schematic flow chart is shown for explaining a method for interrupting a charging process of an energy source of an electric drive.

[0022] In the figures, identical elements or elements with the same function are provided with the same reference symbols. DETAILED DESCRIPTION

[0023] Figure 1A first schematic block diagram of an electric drive 200 is shown. The electric drive 200 is preferably designed for operating a vehicle 400. The electric drive 200 comprises an inverter 210 and a multi-phase electric machine 220. The inverter 210 comprises a positive input connection 212 and a negative input connection 214 on the input side for connecting an energy source 230. A fuse 260 is arranged between the positive connection of the energy source 230 and the positive input connection 212 of the inverter. The fuse 260 is set to block the current very quickly when the current from or into the battery exceeds a predefined threshold value. Preferably, the inverter 210 comprises a second capacitor C2, preferably an intermediate circuit capacitor. On the output side, the inverter 210 comprises a multi-phase connection 215 for connecting a multi-phase electric machine 220, preferably a phase connection for connecting the individual phases or windings of the electric machine 220. The inverter 210 is configured to supply electric energy to the motor 220 in motor operation and to receive electric energy from the motor 220 in generator operation. The inverter includes a plurality of power switches. Power switches 231 ... 236 are arranged in a half-bridge connected in parallel as high-side switches and low-side switches and the half-bridge is connected between the positive input connection 212 and the negative input connection 214 of the inverter. The central tap between the corresponding high-side switch and the low-side switch of the half-bridge is respectively connected to a phase of the multi-phase connection 215. The windings 222, 224, 226 of the multi-phase motor 220 are connected in a star-shaped manner as an example. The connection of the windings in a triangle manner is also feasible. The winding connection 228 of the motor 220, preferably the contact portion at the winding, is connected to the motor connection 240. The winding connection preferably corresponds to the phase connection of the motor. However, as winding connections, contacts between multiple windings of the motor at other locations of the winding, preferably within the winding or at the other end of the winding, are also feasible. The winding connection 228 shown corresponds to the star point of the windings of the motor connected in a star shape. The star point is constructed as a winding connection 228. Advantageously, the current flow of the charging current is directed through one or more windings and switches of the inverter by means of correspondingly controlling the high-side switches and / or low-side switches of the half-bridge of the inverter. This can result in a more uniform load of the power switches (231 ... 236) of the windings and inverter 210. The motor connection 240 is connected to the positive charging connection 216 and the negative input connection 214 is connected to the negative charging connection 218. During the charging process of the energy source 230, the charging energy source 250 is connected to the positive charging connection 216 and the negative charging connection 218. In this case, electrical energy is provided from charging energy source 250 via the windings of the electric machine and inverter 210 for charging energy source 230. Positive and negative charging terminals 216, 218 are preferably provided for connection to charging energy source 250 for charging operation for charging energy source 230.The device 120 is configured to, upon detecting 510 a fault at the high side switches 231, 233, 235 of the first half-bridge of the inverter 210, preferably permanently close the low side switches 232, 234, 236 of the half-bridges of the inverter 210, preferably the low side switches 232, 234, 236 of the first half-bridge of the inverter 210. Preferably, the device 120 comprises a control unit, which preferably has a microcontroller, a memory, a control circuit, a voltage supply, a signal input and / or a signal output for detecting a fault and for closing the low side switches. Accordingly, preferably, an electrical, optical or wireless connection is present between the device 120 and the power switches 231 ... 236 for security. Figure 1 214 and the charging connection 216 , 218 . Preferably, the electric drive 200 includes a switch K1, which is connected between the motor connection 240 and the positive charging connection 216 . Preferably, the switch K1 is closed during the charging operation and is opened during the driving operation of the vehicle (motor operation, generator operation). The switch K1 is preferably designed as an electromechanical switch, that is, as a contactor or a relay. Preferably, the electric drive 200 includes a first capacitor C1, which is connected in parallel with the positive charging connection 216 and the negative charging connection 218 at least during the charging process. The first capacitor C1 preferably attenuates voltage and current fluctuations at the positive and negative charging terminals 216 , 218 which occur during the switching operations of the power switches 231 . . . 236 of the inverter.

[0024] Figure 2 A schematic diagram of a vehicle 400 is shown, which has an electric drive train 300 and the device 120. The vehicle 400 preferably includes four wheels 402, which are preferably driven by means of an electric motor 220. This diagram only shows a possible embodiment of the vehicle 400. Preferably, the vehicle is any vehicle on water, land or air. The drive train 300 includes the device 120, the inverter 210, the preferably multi-phase electric motor 220 and / or the energy source 230. In the diagram, the fuse 260 is integrated in the housing of the energy source 230 by way of example. The preferably electric energy source 230 is connected to the inverter 210 via input connections 212, 214. The charging connections 218, 216 are configured to be connected to a charging energy source 250 (not shown) in a charging operation for charging the energy source 230.

[0025] Figure 3A schematic flow chart is shown for explaining a method 500 for interrupting a charging process of an energy source 230 of an electric drive 200. The method 500 begins with step 505. In step 510, a fault is detected at a high-side switch 231, 233, 235 of a first half-bridge of an inverter 210. In step 520, the low-side switches 232, 234, 236 of the half-bridges of the inverter are closed, preferably the low-side switches 232, 234, 236 of the first half-bridge of the inverter are closed. The method 500 ends with step 525.

Claims

1. A method (500) for interrupting a charging process of an energy source (230) of an electric drive (200), in, The electric drive device (200) comprises an inverter (210) and a multi-phase electric machine (220), wherein the inverter (210) comprises a positive input connection (212) and a negative input connection (214) on the input side for connecting the energy source (230). wherein a fuse (260) is arranged between a positive connection of the energy source (230) and a positive input connection (212) of the inverter, wherein the inverter comprises a multi-phase connection (215) on the output side for connecting the multi-phase motor (220), wherein the inverter (210) comprises a plurality of power switches (231 . . . 236), wherein the power switches (231 . . . 236) are arranged as high-side switches and low-side switches in a half-bridge connected in parallel, and the half-bridge is connected between a positive input connection (212) and a negative input connection (214) of the inverter, wherein a central tap of the half-bridge between the respective high-side switch and the low-side switch is respectively connected to a phase of the multi-phase connection (215), The inverter is configured to supply electrical energy to the electric machine (220) in motor operation and to receive electrical energy from the electric machine (220) in generator operation, wherein at least one of the windings of the multi-phase electric machine (220) comprises a winding connection (228), and the winding connection (228) of the electric machine (220) is connected to a motor connection (240), wherein the motor connection (240) is connected to a positive charging connection (216) and the negative input connection (214) is connected to a negative charging connection (218), wherein, during the charging process of the energy source (230), a charging energy source (250) is connected to the positive charging terminal (216) and the negative charging terminal (218) and provides electrical energy via the inverter (210) for charging the energy source (230), The method comprises the steps of: A fault is identified (510) at a high-side switch (231, 233, 235) of a first half-bridge of the inverter (210); and a low-side switch (232, 234, 236) of a half-bridge of the inverter (210), in particular a low-side switch (232, 234, 236) of the first half-bridge, is closed (520).

2. The method according to claim 1, wherein: A fault at a high-side switch is detected by means of an overcurrent protection circuit, a diagnostic method and / or at least one phase current sensor of the inverter (210).

3. A device (120) for interrupting a charging process of an energy source (230) of an electric drive (200), in, The electric drive device (200) comprises an inverter (210) and a multi-phase electric machine (220), wherein the inverter (210) comprises a positive input connection (212) and a negative input connection (214) on the input side for connecting the energy source (230). A fuse (260) is arranged between the positive terminal of the energy source (230) and the positive input terminal (212) of the inverter. The inverter comprises, on the output side, a multi-phase connection (215) for connecting the multi-phase motor (220), wherein the inverter (210) comprises a plurality of power switches (231 . . . 236), wherein the power switches (231 . . . 236) are arranged as high-side switches and low-side switches in a half-bridge connected in parallel, and the half-bridge is connected between a positive input connection (212) and a negative input connection (214) of the inverter, wherein a central tap of the half-bridge between the respective high-side switch and the low-side switch is respectively connected to one phase of the multi-phase connection (215), The inverter is configured to supply electrical energy to the electric machine (220) in motor operation and to receive electrical energy from the electric machine (220) in generator operation, wherein at least one of the windings of the multi-phase electric machine (220) comprises a winding connection (228), and the winding connection (228) of the electric machine (220) is connected to a motor connection (240), The motor connection (240) is connected to the positive charging connection (216), and the negative input connection (214) is connected to the negative charging connection (218). wherein, during the charging process of the energy source (230), a charging energy source (250) is connected to the positive charging terminal (216) and the negative charging terminal (218) and provides electrical energy to the energy source (230) via the inverter (210), Therein, the device (120) is configured to carry out a method according to any of the preceding claims.

4. A drive train (300) having a device (120) according to claim 3, wherein: The drive system (300) includes the inverter (210), the motor (220) and / or the energy source (230).

5. A vehicle (400) having a drive train (300) according to claim 4.

6. A computer program comprising commands which, when the program is executed by a device according to claim 3, cause the device to carry out the steps of the method (500) according to any one of claims 1 to 2.

7. A computer-readable storage medium comprising commands which, when executed by a device according to claim 3, cause the device to execute the steps of the method (500) according to any one of claims 1 to 2.

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