Method and device for interrupting a charging process of a power source of an electric drive

Abstract

The invention relates to a method (500) for interrupting a charging process of a power source (230) of an electric drive (200), having the steps of: detecting (510) a fault at a highside switch (231, 233, 235) of a first half-bridge of the inverter (210), and closing (520) a lowside switch (232, 234, 236) of a half-bridge of the inverter (210).

Description

[0001] Description

[0002] title

[0003] Method and device for interrupting a charging process of an energy source of an electric drive

[0004] The present invention relates to a method and a device for interrupting a charging process of an energy source of an electric drive, a drive train with the device, a vehicle with a drive train as well as a computer program and a computer-readable storage medium.

[0005] State of the art

[0006] Electromobility is a key component in efforts to develop more environmentally friendly modes of transportation. However, to achieve widespread acceptance of electric vehicles, several prerequisites must be met. In addition to sufficient vehicle range, a widespread supply of energy sources is required to ensure charging of electric vehicles at all times. Furthermore, the required charging time must be kept short to avoid significant delays.

[0007] When charging an electric vehicle at an alternating current (AC) charging station, for example when connecting it to the public power grid, the alternating current is converted into direct current (DC) by a rectifier, preferably located inside the vehicle. Rapid charging stations, which directly provide direct current and are characterized by a shorter charging time, are becoming increasingly common. An example of a DC rapid charging station is known from WO 2012 / 038222 A3. WO 2019 / 215128 A1 discloses an inverter for converting electrical energy from a DC voltage source into an alternating current for driving an electric machine. Furthermore, this inverter is configured to boost the charging voltage of a charging device to a higher voltage. Boost converters of this type are used when the available charging voltage is lower than the voltage required to charge a vehicle battery.Corresponding inverters include switches or relays which, when closed, enable charging and thus a current flow from the charging device via a winding of the electric machine via the inverter controlled as a boost converter into a connected battery. During charging, malfunctions can occur that must be rectified. A fault that is critical for the system is the failure, or the permanently closed state, of an upper power switch of a half-bridge of the inverter. The higher voltage of the vehicle battery to be charged is then permanently applied to the charger, which is only designed for a lower charging voltage. This can lead to the destruction of the charging station. Therefore, there is a need for solutions to detect such malfunctions and minimize the resulting damage.This requires solutions that function safely, reliably and quickly at the high electrical voltages and currents that occur.

[0008] Disclosure of the invention

[0009] The present invention provides a method having the features of patent claim 1, a device having the features of patent claim 3, a drive train having the features of patent claim 4, a vehicle having the features of patent claim 5, a computer program having the features of patent claim 6 and a computer-readable storage medium having the features of patent claim 7.

[0010] The invention therefore relates to a method for interrupting a charging process of an energy source of an electric drive. Preferably, the invention relates to a method for interrupting a charging process of an energy source for or with an electric drive.

[0011] 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 terminal and a negative input terminal on the input side for connecting an energy source, preferably a DC voltage energy source, for example a battery or a traction battery or a fuel cell. A fuse is arranged between the positive terminal of the energy source and the positive input terminal of the inverter. Such a fuse is preferably integrated into a common housing with the energy source. The fuse is preferably designed as a mechanical fuse, an electronic fuse, a hybrid fuse, a fusible fuse, a pyroelectric fuse and / or a semiconductor switch, preferably bidirectional.In battery management systems of battery-electric vehicles, such fuses are preferably provided within the housing of the battery or the energy source. Energy sources for battery-electric vehicles preferably comprise corresponding fuses to prevent a short circuit between the two poles of the energy source or the energy source connection poles. Corresponding fuses advantageously open very quickly if the short-circuit current becomes very high within a short period of time. On the output side, the inverter comprises a multi-phase connection for connecting the phase connections of the multi-phase electrical machine. The inverter is designed to supply the electrical machine with electrical energy in motor operation and to absorb electrical energy from the electrical machine in generator operation. The inverter comprises a plurality of circuit breakers.The power switches are arranged in parallel half-bridges as high-side switches and low-side switches, and the half-bridges are connected between the positive input terminal and the negative input terminal of the inverter. A center tap of each half-bridge between the respective high-side switch and low-side switch is connected to a phase of the multi-phase connection. The inverter's high-side switches and low-side switches are controlled accordingly in motor or generator mode, preferably pulse-width modulated or block-commutated. The energy absorbed in generator mode is preferably passed on to the connected energy source to charge the energy source. The multi-phase electrical machine comprises several windings, preferably at least one 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 electrical machine comprises a further winding connection. The winding connection is connected to a motor connection. Preferably, a winding connection is formed as one of the two connection contacts at the ends of a winding. Preferably, a winding connection can also be formed between the two ends of a winding. Consequently, a winding connection is preferably connected to a phase connection of the electrical machine or arranged between at least two of the windings of the multi-phase machine or within a winding of the windings of the multi-phase machine. The winding connection of the electrical machine is connected to a motor connection. Preferably, the motor connection is a contact that is connected to the winding connection.The motor connection is connected to a positive charging connection. The negative input connection is connected to a negative charging connection. The electric drive preferably comprises a switch which is connected between the motor connection and the positive charging connection. The switch is preferably closed during charging operation and open during driving operation of the vehicle (motor operation, generator operation). The switch is preferably designed as an electromechanical switch, i.e. as a contactor or as a relay. The electric drive preferably comprises a first capacitor which, at least during the charging process, is connected in parallel to the positive charging connection and the negative charging connection. The first capacitor preferably dampens the voltage and current fluctuations at the positive and negative charging connections which arise during the switching operations of the power switches of the inverter.During the charging process of the energy source, a charging energy source is connected to the positive charging terminal and the negative charging terminal. Electrical energy from the charging energy source is provided via the inverter to charge the energy source. The charging energy source is preferably a charging station or charging column, preferably in the infrastructure that provides electrical energy for charging energy sources of vehicles. Electrical energy is preferably provided by means of the charging energy source to charge an energy source connected to the input terminal. When charging the energy source, a charging current preferably flows from the charging energy source via the positive charging terminal, via the motor terminal, 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 terminal into the energy source.

[0012] Connecting and disconnecting or uncoupling or connected and separated is used synonymously with galvanically connected and galvanically separated.

[0013] Preferably, the windings of the multi-phase electric machine are connected in a star configuration. The star point of the electric machine is configured as a winding connection. Preferably, the electric drive comprises an inverter and an electric machine whose windings are connected in a star configuration, with the star point of the electric machine configured as a winding connection. The winding connection is connected to the motor connection. Preferably, an electrical circuit is provided that enables a switchable charging connection for connecting and disconnecting a charging energy source to an electric drive via the star point of the electric machine.

[0014] The method comprises the steps of: detecting a fault in a high-side switch of a first half-bridge of the inverter and closing a low-side switch of a half-bridge, in particular the low-side switch of the first half-bridge of the inverter. This sequence of steps first determines that a fault exists. Preferably, a fault is detected when a high-side switch is closed and can no longer be opened. In particular, a signal to open the switch is present at the control input of the high-side switch and the switch remains closed. In this fault case, a high current flows through the switch and a minimal voltage drops across the switch. If this state were to persist, the current direction would reverse during charging from the charging energy source to the energy source. This would result in an unbridled current flowing from the energy source towards the charging energy source.However, the charging energy source and internal or connected components, such as intermediate circuit capacitors, are not designed for the high voltage of the energy source. This would lead to destruction of the charging energy source and other components. Therefore, the second step is implemented, preferably immediately and / or permanently, to prevent destruction of the charging energy source. A low-side switch of a half-bridge, preferably the low-side switch of the first half-bridge, is closed. This leads to an immediate short-circuit of the energy source via the two power switches of the inverter, involving at least one winding of the electrical machine, preferably to a short-circuit of the energy source via the two power switches of a first half-bridge of the inverter. Alternatively, two of the low-side switches can also be closed, preferably those of a second and third half-bridge.The rapidly developing high current also flows through the fuse. The fastest current rise, and thus the fastest fuse blowing, occurs when the short circuit occurs only through the two circuit breakers of the first half-bridge of the inverter. The fuse then opens the circuit reliably, safely, and very quickly, eliminating the immediate danger of destroying the charging power source.

[0015] Advantageously, a method for the electric drive is provided that prevents the charging energy source from being destroyed during the charging process. No additional circuitry is required for this. If the fuse is non-reversible, it would preferably have to be replaced subsequently in a workshop. Preferably, the fault in the high-side switch in the inverter would also be rectified. Preferably, the total damage to be rectified is significantly less than the potential damage to the charging energy source.

[0016] In one embodiment, the fault on the high-side switch is detected by means of an overcurrent protection circuit, diagnostic procedures and / or at least one phase current sensor of the inverter.

[0017] To implement the method, circuit components are used that are also used for regular operation of the electric drive. For example, the fault on the high-side switch of a first half-bridge of the inverter is preferably detected by an existing overcurrent protection circuit. This circuit is used for the shuttle operation of the inverter or the electric drive to detect high loads on a circuit breaker in the inverter and to avoid excessive loads using suitable operating strategies. Alternatively or additionally, further diagnostic methods are used for detection, which are preferably also used during shuttle operation of the electric drive. Likewise, alternatively or additionally, measured values ​​from at least one phase current sensor are taken into account to detect the fault.

[0018] Advantageously, a method for detecting the fault in a high-side switch for use during the charging process is provided.

[0019] The invention further comprises a device for interrupting a charging process of an energy source of an electric drive. The device is configured to carry out the described method. The device preferably comprises a control unit, preferably with a microcontroller, a power supply, at least one signal input, preferably for detecting an error, and / or at least one signal output, preferably for closing the low-side switch. Advantageously, a device is provided that is configured to prevent destruction of a charging energy source during a charging process.

[0020] Furthermore, the invention relates to a drive train with the described device, wherein the drive train comprises the inverter, the preferably multi-phase electric machine, and / or the energy source. Advantageously, a drive train is provided with a device configured to prevent destruction of a charging energy source during a charging process. This enables safe operation of the drive train.

[0021] The invention further relates to a vehicle with the drive train. Advantageously, a vehicle is provided with the device configured to prevent destruction of a charging energy source during a charging process. This enables safe operation of the vehicle.

[0022] Furthermore, the invention relates to a computer program comprising instructions which, when the program is executed by a device, cause the device to carry out the steps of the described method.

[0023] 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.

[0024] Short description of the drawings

[0025] They show:

[0026] FIG. 1 shows a first schematic block diagram of an electric drive with a device;

[0027] FIG. 2 is a schematic representation of a vehicle with an electric drive train with a device;

[0028] FIG. 3 shows a schematic flow diagram for explaining a method for interrupting a charging process of an energy source of an electric drive.

[0029] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0030] Description of the embodiments

[0031] Figure 1 shows a first schematic block diagram of an electric drive 200. The electric drive 200 is preferably designed to operate a vehicle 400. The electric drive 200 comprises an inverter 210 and a multi-phase electric machine 220. The inverter 210 comprises, on the input side, a positive input terminal 212 and a negative input terminal 214 for connecting a power source 230. A fuse 260 is arranged between the positive terminal of the power source 230 and the positive input terminal 212 of the inverter. The fuse 260 is configured to very quickly prevent a current flow from or into the battery if this current exceeds a predeterminable threshold value. The inverter 210 preferably comprises a second capacitor C2, preferably an intermediate circuit capacitor.On the output side, the inverter 210 comprises a multiphase connection 215 for connecting the multiphase electrical machine 220, preferably for connection to the phase connections of the individual phases, or the windings, of the electrical machine 220. The inverter 210 is configured to supply the electrical machine 220 with electrical energy in motor mode and to absorb electrical energy from the electrical machine 220 in generator mode. The inverter comprises a plurality of power switches. The power switches 231...236 are arranged in parallel-connected half-bridges as high-side switches and low-side switches, and the half-bridges are connected between the positive input terminal 212 and the negative input terminal 214 of the inverter.A center tap of a half-bridge between the respective high-side switch and low-side switch is connected to a phase of the multi-phase connection 215. The windings 222, 224, 226 of the multi-phase electrical machine 220 are, for example, connected in a star configuration. A delta connection of the windings is also possible. A winding connection 228, preferably a contact on a winding, of the electrical machine 220 is connected to a motor connection 240. The winding connection preferably corresponds to a phase connection of the electrical machine. However, a contact at another point on the winding, preferably within the winding or at the other end of the winding, between the multiple windings of the electrical machine, is also possible as a winding connection. The illustrated winding connection 228 corresponds to the star point of the windings of the electrical machine connected in a star configuration.The star point is formed as a winding connection 228. Advantageously, by appropriately controlling the high-side switches and / or low-side switches of the inverter's half-bridges, the flow of a charging current is directed specifically through one or more windings and switches of the inverter. This allows a more even load on the windings and power switches (231...236) of the inverter 210 to be achieved. 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. During the charging process of the energy source 230, a charging energy source 250 is connected to the positive charging connection 216 and the negative charging connection 218. Electrical energy from the charging energy source 250 is provided via the windings of the electric machine and the inverter 210 to charge the energy source 230.Preferably, the positive and negative charging terminals 216, 218 are configured to be connected to a charging energy source 250 for charging operation to charge the energy source 230. The device 120 is configured to close, preferably permanently, a low-side switch 232, 234, 236 of a half-bridge of the inverter 210, preferably the low-side switch 232, 234, 236 of the first half-bridge of the inverter 210, depending on the detection 510 of a fault at a high-side switch 231, 233, 235 of a first half-bridge of the inverter 210. The device 120 preferably comprises a control unit, preferably with a microcontroller, a memory, a control circuit, a voltage supply, signal inputs, and / or signal outputs for detecting a fault and closing the low-side switch. Accordingly, existing electrical, optical or wireless connections between the device 120 and the circuit breakers 231 are preferred.236 are not shown to maintain the clarity of Figure 1. Preferably, the device 120 is arranged with the inverter 210 and / or the electric machine 220 within a common housing. Alternatively, the device 120 can be arranged in a separate housing and connected by means of cables to the respective terminals and connections to the electric machine 220, the inverter 210 and / or the input terminal 212, 214 and the charging terminal 216, 218. Preferably, the electric drive 200 comprises a switch K1, which is connected between the motor terminal 240 and the positive charging terminal 216. Preferably, the switch K1 is closed during charging operation and open during driving operation of the vehicle (motor operation, generator operation). The switch K1 is preferably designed as an electromechanical switch, i.e. as a contactor or as a relay.

[0032] The electric drive 200 preferably comprises a first capacitor CI, which, at least during the charging process, is connected in parallel to the positive charging terminal 216 and the negative charging terminal 218. Preferably, the first capacitor CI dampens the voltage and current fluctuations at the positive and negative charging terminals 216, 218 that arise during the switching operations of the power switches 231...236 of the inverter.

[0033] Figure 2 shows a schematic representation of a vehicle 400 with an electric drive train 300 and the device 120. The vehicle 400 preferably comprises four wheels 402, which are preferably driven by the electric machine 220. This representation shows only one possible embodiment of a vehicle 400. The vehicle is preferably any vehicle on water, on land, or in the air. The drive train 300 comprises the device 120, the inverter 210, the preferably multi-phase electric machine 220 and / or the energy source 230. In the representation, the fuse 260 is integrated, by way of example, in the housing of the energy source 230. The electrical energy source 230 is preferably connected to the inverter 210 via the input connections 212, 214. The charging connections 218, 216 are designed to be connected to a charging energy source 250 (not shown) during charging operation for charging the energy source 230.

[0034] Figure 3 shows a schematic flowchart 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 the inverter 210. In step 520, a low-side switch 232, 234, 236 of a half-bridge of the inverter, preferably the low-side switch 232, 234, 236 of the first half-bridge of the inverter, is closed. The method 500 ends with step 525.

Claims

Claims 1. Method (500) for interrupting a charging process of an energy source (230) of an electric drive (200), wherein the electric drive (200) comprises an inverter (210) and a multi-phase electric machine (220), wherein the inverter (210) comprises, on the input side, a positive input terminal (212) and a negative input terminal (214) for connecting the energy source (230), wherein a fuse (260) is arranged between the positive terminal of the energy source (230) and the positive input terminal (212) of the inverter, wherein the inverter comprises, on the output side, a multi-phase terminal (215) for connecting the multi-phase electric machine (220), wherein the inverter (210) comprises a plurality of circuit breakers (231...236), wherein the circuit breakers (231...236) are arranged in parallel-connected half-bridges as high-side switches and low-side switches, and the half-bridges are connected between the positive input terminal (212) and the negative input terminal (214) of the inverter, wherein a center tap of a half-bridge between the respective high-side switch and low-side switch is connected to a phase of the multi-phase terminal (215), wherein the inverter is configured to supply the electrical machine (220) with electrical energy in a motor mode and to absorb electrical energy from the electrical machine (220) in a generator mode, wherein at least one of the windings of the multi-phase electrical machine (220) comprises a winding terminal (228), and the winding terminal (228) of the electrical machine (220) is connected to a motor terminal (240). wherein the motor terminal (240) is connected to a positive charging terminal (216) and the negative input terminal (214) is connected to a negative charging terminal (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), comprising the steps: Detecting (510) a fault at a high-side switch (231, 233, 235) of a first half-bridge of the inverter (210); Closing (520) a low-side switch (232, 234, 236) of a half-bridge, in particular the low-side switch (232, 234, 236) of the first half-bridge, of the inverter (210). The method according to claim 1, wherein the fault in the high-side switch is detected by means of an overcurrent protection circuit, diagnostic methods, and / or at least one phase current sensor of the inverter (210).Device (120) for interrupting a charging process of an energy source (230) of an electric drive (200), wherein the electric drive (200) comprises an inverter (210) and a multi-phase electric machine (220), wherein the inverter (210) comprises, on the input side, a positive input terminal (212) and a negative input terminal (214) for connecting the energy source (230), wherein a fuse (260) is arranged between the positive terminal of the energy source (230) and the positive input terminal (212) of the inverter, wherein the inverter has, on the output side, a multi-phase terminal (215) for connecting the multi-phase electric machine (220). wherein the inverter (210) comprises a plurality of power switches (231..236), wherein the power switches (231..236) are arranged in parallel-connected half-bridges as high-side switches and low-side switches, and the half-bridges are connected between the positive input terminal (212) and the negative input terminal (214) of the inverter, wherein a center tap of a half-bridge between the respective high-side switch and low-side switch is connected to a phase of the multi-phase terminal (215), wherein the inverter is configured to supply the electric machine (220) with electrical energy in a motor mode and to absorb electrical energy from the electric machine (220) in a generator mode,wherein at least one of the windings of the multi-phase electric machine (220) comprises a winding terminal (228), and the winding terminal (228) of the electric machine (220) is connected to a motor terminal (240), wherein the motor terminal (240) is connected to a positive charging terminal (216) and the negative input terminal (214) is connected to a negative charging terminal (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) to the energy source (230), wherein the device (120) is configured to control a method according to one of the preceding claims. Drive train (300) with a device (120) according to claim 3, wherein the drive train (300) comprises the inverter (210),the electric machine (220) and / or the energy source (230). Vehicle (400) with a drive train (300) according to claim 4., A computer program comprising instructions which, when executed by a device according to claim 3, cause the device to perform the steps of the method (500) according to any one of claims 1 to 2. A computer-readable storage medium comprising instructions which, when executed by a device according to claim 3, cause the device to perform the steps of the method (500) according to any one of claims 1 to 2.

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