Vehicle electrical system with an energy storage unit and charging ports

Abstract

Vehicle electrical system with an energy storage device (ES), a direct current charging connection (GA) and an alternating current charging connection (WA), wherein the vehicle electrical system further comprises a power low-pass filter (ZF) which connects a first section (A1) of the vehicle electrical system to a second section (A2) of the vehicle electrical system, wherein the direct current charging connection (GA) and the energy storage device (ES) are provided in the second section (A2) and the alternating current charging connection (WA) is provided in the first section (A1), wherein the vehicle electrical system further comprises at least one consumer (EKK, AUX, EH, GW, INV, M) which is connected to the power low-pass filter (ZF) via an additional filter (F1 - F4; FM) associated with the consumer, the at least one consumer is provided in the first section (A1) and at least one further consumer is provided in the second section (A2), and wherein the at least one further consumer in the second Section (A2) is designed as an electrical machine (M) which is connected to the associated additional filter (FM) via an inverter (INV).

Description

[0001] Electric vehicles, i.e., purely electric vehicles and hybrid vehicles, have an electrical energy storage unit. To charge this unit externally, such vehicles must have a charging port. This port is designed to supply energy for charging into the vehicle and thus also into the energy storage unit. Direct or alternating current can be used for this purpose. Vehicles with such charging ports are also referred to as "plug-in vehicles."

[0002] DE 10 2017 008 840 A1 discloses an electrical system for a motor vehicle driven by at least one electric motor, comprising a vehicle battery and a clocked energy converter for supplying the electric motor with an electrical machine voltage during normal driving operation of the motor vehicle. The clocked energy converter has a DC intermediate circuit that is electrically coupled to the vehicle battery and has at least one Y capacitor to establish electromagnetic compatibility.The electrical system comprises an AC charging unit connected to the vehicle battery, which is designed to be connected to a charging station external to the motor vehicle and to be supplied with an AC charging voltage on the charging station side, wherein the DC intermediate circuit is electrically coupled to the vehicle battery by means of a switching unit, wherein the switching unit is designed to electrically separate the DC intermediate circuit from the vehicle battery when the vehicle battery is being charged by means of the AC charging unit.

[0003] US 2014 / 0 062 394 A1 discloses a multi-mode battery charging device for a vehicle. The charging device includes a controller. The controller is electrically coupled to a plurality of charging systems. Each charging system is configured to supply a first power from an external power source and to convert the first power to a second power suitable for storage in at least one battery in the vehicle. The controller is configured to allow a first charging system of the plurality of charging systems to supply the first power based on a charging priority order when it is determined that two or more of the plurality of charging systems are simultaneously supplying the first power to the vehicle.

[0004] EP 2 657 063 A1 discloses a charging device for installation in an electric vehicle for charging an electrical energy storage device of the electric vehicle. The charging device comprises a first energy transmission interface connected to an energy storage-side connection via a first electrical energy path. The charging device comprises a second energy transmission interface connected to the energy storage-side connection via a second electrical energy path.

[0005] DE 10 2009 033 185 A1 discloses a charging system and a charging method for charging a vehicle battery, as well as a vehicle with such a charging system. The charging system comprises a converter, a switching unit, and at least one mains charging connection.

[0006] DE 10 2011 005 911 A1 discloses a charging device for a high-voltage battery, in particular a high-voltage battery of a motor vehicle. A rectifier of the charging device can be controlled by a control device to vary the DC voltage used as the charging voltage within a DC voltage range.

[0007] US 5,132,894 A shows an active damping circuit. The active damping circuit comprises a capacitor and a switching circuit.

[0008] In addition to the charging circuits (for connecting the charging ports), the electrical system of such a vehicle also has other components that operate in a pulsed manner. This pulsed switching results in interference in the electrical system. On the one hand, electromagnetic compatibility must prevent interference from disrupting other components during operation, and on the other hand, interference from the vehicle's electrical system must be prevented. EMC filters are used for this purpose.

[0009] Due to the large number of components that can be connected to a vehicle electrical system, numerous filters are required to connect the corresponding components. These filters suppress the interference emanating from the components and also serve to prevent interference from the components. Since these filters are associated with significant costs, one objective is to demonstrate a way to reduce the costs of EMC-compatible design of the vehicle electrical system. This objective is achieved by the vehicle electrical system of claim 1. Further features, embodiments, properties, and advantages are set out in the dependent claims.

[0010] A vehicle electrical system is proposed in which a power low-pass filter is used as the central filter. The central filter connects a first section of the vehicle electrical system to a second section, the energy storage device being provided in the second section and an AC charging connection being provided in the first section. Further components are therefore also provided in the first section, so that the central filter serves as a common filter for these components and for the AC charging connection. An electrical energy storage device of the vehicle electrical system is accommodated in the second section, i.e. starting from the power low-pass filter and beyond the AC charging connection. This energy storage device is in particular an accumulator such as a high-voltage accumulator, for example a traction accumulator.

[0011] A DC charging port is also provided in the second section, which is connected, in particular, without an additional filter element (i.e., without a filter), to the energy storage device in the second vehicle electrical system. This DC charging port is preferably connected to the energy storage device without an additional converter. The second section also provides an inverter and an electric motor, which are connected to the energy storage device and also to the power low-pass filter via an additional filter. Interference generated in the inverter is thus filtered by the additional filter and also by the power low-pass filter, and is thus significantly attenuated until it enters the first section.

[0012] A vehicle electrical system with an energy storage device is thus described, wherein the vehicle electrical system further comprises a direct current charging connection and an alternating current charging connection. Furthermore, the vehicle electrical system has a power low-pass filter (as a central filter). This connects a first section of the vehicle electrical system to a second section of the vehicle electrical system. The two sections have the same nominal voltage and are, in particular, high-voltage electrical systems. The direct current charging connection and the energy storage device are provided in the second section, and the alternating current charging connection is provided in the first section. Switching pulses in an alternating current rectifier, which connects the alternating current connection to the power low-pass filter, thus only reach the energy storage device in an attenuated manner through the power low-pass filter. The first section is, in particular, a (preferably fully) shielded section.In particular, the DC connection, the connection between the DC connection and a connection point to which the central filter is also connected are unshielded.

[0013] As mentioned, the vehicle electrical system has at least one consumer in the first section. These consumers can correspond to the components mentioned above. The at least one consumer is connected to the power low-pass filter via an additional filter, with the additional filter being assigned to the consumer. If there are multiple consumers, an additional filter belonging only to this consumer connects the consumer to the power low-pass filter. In other words, a supply bus results in the first section, to which the at least one consumer is connected via an associated additional filter. This supply bus is connected to the power low-pass filter.

[0014] The power low-pass filter occupies a central position within the vehicle's electrical system. The power low-pass filter is also called a central filter. The power low-pass filter connects the supply bus (or the first section) with the second section of the vehicle's electrical system.

[0015] At least one electrical heating element can be considered as a consumer in the first section. For example, the heating element can be a heating element for an electrically heatable catalyst (of an exhaust gas purification device) or an electrical heater that is thermally connected, for example, to the air conditioning system and / or to a cooling circuit for components of the vehicle. Alternatively, or in combination with this, the at least one consumer can comprise an electric air conditioning compressor.

[0016] The loads are, in particular, clocked loads and thus have at least one power actuator which clocks the current, for example, using pulse width modulation, to adjust the power. The load can also be connected to the power low-pass filter via a clocked power actuator or via a clocked converter (as well as via the additional filter). The additional filter assigned to the respective load can be adapted to the frequency or to the interference spectrum that the load emits through this clocking. As a load, in particular in the first section, a DC-DC converter can alternatively or additionally be provided, in particular a DC-DC converter which connects a low-voltage electrical system branch to the rest of the vehicle electrical system, in particular to a part of the vehicle electrical system that is designed as a high-voltage electrical system.The prefix "low-voltage" refers to elements and parts with a nominal voltage below 60 volts, for example, a nominal voltage of 12 volts, 13 volts, 14 volts, 24 volts, or 48 volts. This can be a galvanically isolating DC-DC converter, particularly one designed as a step-down converter.

[0017] At least one further consumer is arranged in the second section. Here, the actual consumer is the electrical machine, while the inverter can be described as an actuator that operates in a clocked manner. Thus, the at least one further consumer provided in the second section is designed as an electrical machine. This electrical machine is connected to the associated additional filter via the inverter. The additional filter thus connects the inverter to the central filter. One possibility is to regard the at least one consumer, preferably provided in the second section, as an electrical drive that has an electrical machine and an inverter. This drive is connected as a consumer to the power low-pass filter via the associated additional filter. As mentioned, the inverter forms the clocked actuator. The consumer is the electrical machine.The inverter can be bidirectional to enable energy recuperation by means of the electric machine.

[0018] To optimize costs, the auxiliary filters can be designed with lower attenuation or attenuation performance than the power low-pass filter. The power low-pass filter can have a coupling attenuation that is at least 10 dB, 15 dB, or 20 dB greater than that of the auxiliary filter. This can be particularly true for frequencies below 10 MHz, for example, for frequencies below 0.3 MHz, for frequencies below 1.8 MHz, or even for frequencies below 100 kHz. In particular, the auxiliary filters and the power low-pass filter can correspond to different classes of the CISPR 25:2016 standard. The power low-pass filter can be designed according to Class 5 (of the aforementioned standard). The auxiliary filter can be designed as a Class 3 filter (of the aforementioned standard) (and thus permit greater interference than the power low-pass filter).The specified interference limits can refer to operation at rated power or at the maximum power of the load. Costs can be saved by designing the additional filters according to Class 3 (and not Class 5), with the central filter as a Class 5 filter connecting the components of the first section to the second section (where the energy storage device is located). This means that the same Class 5 filter is used by a large number of loads, resulting in two filter stages for the loads with the additional filter: the additional filter and the power low-pass filter. The attenuation between two ports of the filter is referred to as attenuation or coupling attenuation. Alternatively, attenuation can also relate to the transmission path between a port of the filter and the environment, i.e. the attenuation of radiated signals attributable to the filter.The term “class” refers to the CISPR25:2016 standard and in particular concerns the class definitions according to “HV-Limits for conducted voltage measurements at shielded power supply devices” or “Examples of limits for conducted disturbances - Voltage method” or “Examples of limits for conducted disturbances - Current probe method”.

[0019] The vehicle electrical system may also include an inductive charging interface. This may be provided in the first section.

[0020] The induction charging interface can be connected to an induction charging rectifier or, via this, to the power low-pass filter. The induction charging rectifier can be connected to the power low-pass filter without a filter. "Filterless" refers here to connections that have no or only low attenuation, whereby low attenuation also includes attenuation achieved by filters of classes 2 and 1 of the aforementioned standard. In other words, the term "filterless" means that the connection in question does not achieve the attenuation of a filter according to classes 3, 4, or 5 of the CISPR 25:2016 standard, but provides (weaker) attenuation for alternating components. Since, depending on the frequency, bare wires also have a filtering effect due to their inductance per unit length, the term "filterless" does not imply that the connection in question is completely free of inductance.

[0021] The AC charging port is preferably connected to an AC rectifier. This connects the AC charging port to the power low-pass filter. The AC rectifier is preferably connected to the power low-pass filter without a filter. The term "filterless" is to be understood as previously stated.

[0022] The DC charging port can be connected to the power low-pass filter without a converter and, in particular, can also be connected to the energy storage device without a converter. The DC charging port is preferably connected to the power low-pass filter without a filter. The term "filterless" can, in particular, correspond to the definition mentioned above.

[0023] The energy storage device is connected to the power low-pass filter. The connection is, in particular, filterless. Here, too, the term "filterless" has already been defined above.

[0024] The energy storage device is preferably designed as a traction battery, in particular a lithium battery. The DC charging port can be connected to the power low-pass filter via a transient / overvoltage protection device (burst and surge filter). Since such components have attenuation lower than that of filters according to Class 3, 4, or 5 of the CISPR 25:2016 standard, a connection that includes this protection is considered filterless.

[0025] Preferably, a controller is also provided that is configured to alternately operate the AC rectifier of the AC charging port and the induction charging rectifier of the induction charging interface, or to provide both in an inactive state. In particular, such a controller is configured to suppress activation of the induction charging rectifier when the AC rectifier of the AC charging port is active, and to prevent activation of the AC rectifier of the AC charging port when the induction charging rectifier or the induction charging interface is active.

[0026] The central filter, i.e., the power low-pass filter, is designed in particular for a nominal or maximum current of no more than 70 A, in particular of substantially 66 or 65 A. The additional filters are preferably designed for a nominal or maximum current of no more than 50%, 40%, 35%, 33%, or 30% of the current rating of the power low-pass filter.

[0027] The Fig. 1 shows a schematic representation of an embodiment of a vehicle electrical system.

[0028] The Fig.1 shows an exemplary embodiment of an on-board electrical system described here, comprising a first section A1 and a second section A2. The two sections A1, A2 are connected to one another via a central filter ZF, which is referred to as a power low-pass filter. The first section A1 of the vehicle's on-board electrical system comprises consumers such as a heater of an electrically heatable catalytic converter system EH, an electrical heating element EKK of a cooling circuit, and another consumer AUX, which can be designed, for example, as an electric air conditioning compressor. These consumers are connected to the central filter ZF via respective additional filters F1 to F3. An on-board electrical system branch NVBZ for auxiliary consumers is connected to the power low-pass filter ZF via a DC-DC converter GW and another additional filter F4.The on-board power supply branch NVBZ and the DC-DC converter GW can be considered an additional load connected to the power low-pass filter ZF via an additional filter F4. The DC-DC converter GW is preferably galvanically isolated. The on-board power supply branch NVBZ is designed for a nominal voltage of, for example, 12 volts. The DC-DC converter GW is configured so that the nominal voltage in the remaining first section A1, which is designed for high-voltage applications, for example, for nominal voltages of at least 400 volts, 600 volts, or 800 volts, is higher than the nominal voltage of the on-board power supply branch NVBZ.

[0029] The first section also shows an AC connection WA and an inductive charging interface IS. These are connected to the central filter ZV via a respective converter or rectifier. The AC charging connection WA is connected to the central filter via the converter W1, wherein the converter W1 is designed as an AC rectifier, in particular as a controllable rectifier. The converter W1 can have a filter, the attenuation of which, however, is lower than the attenuation of the filters F1 to F4, the filter FM (explained below), and the central filter ZF. The inductive charging interface is connected to the central filter via the inductive charging rectifier W2, wherein the converter W2 is also designed as a clocked rectifier.The induction charging rectifier W2 can also be designed as a clocked rectifier and in particular have damping elements, the damping strength of which, however, is preferably lower than the damping of the filters F1 to F4, the filter FM and in particular the power low-pass filter ZF.

[0030] The power low-pass filter ZV (which can also be referred to as a central filter) connects the first section A1 with a second section A2. This contains an energy storage device ES, in particular in the form of a high-voltage accumulator. This is connected (essentially without a filter) to the power low-pass filter ZV. Furthermore, an electric drive is provided in the second section A2, in particular an inverter INV and an electric machine M connected to it. The inverter and the electric machine are connected to the power low-pass filter ZF via the additional filter FM. The inverter connects the electric machine to the power low-pass filter ZF via the additional filter FM. If interference is therefore generated in the inverter INV, it only reaches the on-board power system branch NVBZ through a total of three filter stages, namely the filter stages FM, ZF, F4.

[0031] It should be noted that the central filter IF produces a greater attenuation effect than the filter F4 and also than the filter FM. In general, the central filter IF has greater attenuation than any of the additional filters F1 to F4, as well as FM.

[0032] In section A2, the energy storage device ES is connected essentially without a filter to the additional filter FM. The energy storage device ES is also connected without a filter to the power low-pass filter ZF. The second section A2 of the vehicle electrical system shown further comprises a DC voltage connection GA. This is connected to the power low-pass filter ZF via an overvoltage and transient protection device SB. This connection comprises a switch S, which serves, for example, as a disconnector, which can be open in particular in the event of a fault, or which is open when the vehicle is not being charged via the DC voltage charging interface GA. It can be seen that section A2 has a common connection point VP, to which the battery ES and the power low-pass filter ZF are connected. The DC voltage charging connection GA is also connected to this (via the transient and overvoltage protection device SB). Furthermore, the electric machine orthe inverter connected to it is connected to the connection point VP via the additional filter.

[0033] Section A2 comprises a connection point or supply bus B1, to which numerous consumers are connected via respective additional filters (F1 to F4). Furthermore, the AC charging connection WA is connected to this supply bus B1 (corresponding to a voltage rail) (via the AC rectifier W1). Furthermore, the inductive charging interface IS is connected to this bus B1 via the corresponding inductive charging rectifier W2. The bus is also connected to the power low-pass filter ZF. This connects the bus B1 of the first section A1 to the connection point VP of section A2. The bus B1 of section A1 is designated by the reference symbol B1, and the connection point of section A2 is designated by the reference symbol VP.

[0034] In a specific embodiment, the additional filters, in particular the illustrated additional filters F1 to F4 and FM, are designed according to Class 3 of the CISPR 25:2016 standard, while the power low-pass filter ZF is designed according to Class 5 of this standard. In particular, the charging connections of section A1 are shielded. Section A2 contains the DC charging connection GA, which can be unshielded. Preferably, the connections within section A2 are also partially or fully shielded.

Claims

[1] Vehicle electrical system with an energy storage device (ES), a direct current charging connection (GA) and an alternating current charging connection (WA), wherein the vehicle electrical system further comprises a power low-pass filter (ZF) which connects a first section (A1) of the vehicle electrical system to a second section (A2) of the vehicle electrical system, wherein the direct current charging connection (GA) and the energy storage device (ES) are provided in the second section (A2) and the alternating current charging connection (WA) is provided in the first section (A1), wherein the vehicle electrical system further comprises at least one consumer (EKK, AUX, EH, GW, INV, M) which is connected to the power low-pass filter (ZF) via an additional filter (F1 - F4; FM) associated with the consumer, the at least one consumer is provided in the first section (A1) and at least one further consumer is provided in the second section (A2), and wherein the at least one further consumer in the second Section (A2) is designed as an electrical machine (M) which is connected to the associated additional filter (FM) via an inverter (INV). [2] Vehicle electrical system according to claim 1, wherein the at least one power low-pass filter (IF) for frequencies below 10 MHz has a coupling attenuation which is at least 15 dB greater than that of the additional filter. [3] Vehicle electrical system according to one of the preceding claims, further comprising an induction charging interface (IS) provided in the first section (A1). [4] Vehicle electrical system according to claim 3, wherein the induction charging interface (IS) is connected to an induction charging rectifier (W2) which is connected without a filter to the power low-pass filter (ZF). [5] Vehicle electrical system according to one of the preceding claims, wherein the AC charging connection (WA) is connected to an AC rectifier (W1) which is connected without a filter to the power low-pass filter (ZF). [6] Vehicle electrical system according to one of the preceding claims, wherein the direct current charging connection (GA) is connected to the power low-pass filter (ZF) without a filter. [7] Vehicle electrical system according to one of the preceding claims, wherein the energy storage device (ES) is connected to the power low-pass filter (ZF) without a filter. [8] Vehicle electrical system according to one of the preceding claims, wherein the energy storage device (ES) is designed as a traction accumulator.

Images