Emergency operation of low-voltage electrical equipment of electric vehicle

Abstract

The invention relates to a method for operating a low-voltage (NV) consumer of an electric vehicle, in which an operating voltage is provided to operate the low-voltage consumer of the electric vehicle, and to a powertrain for an electric vehicle, as well as to an electric vehicle.

Description

Technical Field

[0001] The invention relates to a method for operating a low voltage (NV) consumer / consumer / load of an electric vehicle, wherein the low voltage consumer of the electric vehicle is operated using a provided operating voltage. The invention also relates to a power system for an electric vehicle and an electric vehicle. Background Art

[0002] Electric vehicles usually include a high voltage (HV) battery that provides an operating voltage for the power system of the electric vehicle. The operating voltage provided by the high voltage battery can be a DC voltage of several hundred volts. The term "battery" is generally understood as an electrical energy storage. The electric vehicle is preferably designed as a pure electric vehicle (BEV).

[0003] The high-voltage power electronic device of the electric vehicle generates a multi-phase AC voltage according to the provided operating voltage, and the multi-phase AC voltage enables the power motor of the electric vehicle to operate. The high-voltage power electronic device and the power motor are high-voltage electrical devices installed in the electric vehicle.

[0004] In addition, electric vehicles include a number of low-voltage electrical devices. The DC-DC converter of the electric vehicle, which is connected to the high-voltage battery, i.e., the DC converter, provides operating voltage for the low-voltage electrical devices, i.e., the low-voltage electrical devices also operate using the power provided by the high-voltage battery. The operating voltage provided by the DC-DC converter is usually 12V.

[0005] For example, DE 10 2017 114 339 A1 discloses a power supply system for an electric vehicle with a high-voltage battery, which may include multiple independent battery branches. The system also includes a DC-DC converter connected to the high-voltage battery, which provides operating voltage for low-voltage electrical equipment. The DC-DC converter can be directly connected to each battery branch so that even if a single battery branch fails or the high-voltage contacts of the high-voltage battery cut off the voltage for safety reasons, such as due to an accident in the electric vehicle, the operating voltage is provided for the low-voltage electrical equipment.

[0006] In addition, the electric vehicle may further include a low-voltage battery, which provides an operating voltage for low-voltage electrical equipment. The operating voltage provided by the low-voltage battery is usually 12V.

[0007] CN 206 954 014U and CN 108 638 983A disclose a power supply system for an electric vehicle, the power supply system comprising a high voltage battery, a low voltage battery and a bidirectional DC to DC converter connected to the high voltage battery and the low voltage battery. In the event of failure of the high voltage battery, the high voltage electrical equipment of the electric vehicle can be operated using the electrical energy provided by the low voltage battery.

[0008] Likewise, in the event of a high-voltage battery failure, low-voltage electrical equipment can continue to operate using electrical energy provided by the low-voltage battery.

[0009] However, after the high-voltage battery fails, either the operating time of the low-voltage consumers is too short, or the capacity of the low-voltage battery must be large, which results in high cost and high mass of the electric vehicle. Summary of the invention

[0010] Therefore, the object of the present invention is to provide a method for operating a low-voltage electrical device of an electric vehicle, which method can realize long-term operation of the low-voltage electrical device in the event of a high-voltage battery failure, and can be realized at low cost without significantly increasing the weight of the electric vehicle. Other objects of the present invention are to provide a power system for an electric vehicle and an electric vehicle.

[0011] The subject of the invention is a method for operating a low-voltage consumer of an electric vehicle, wherein the low-voltage consumer of the electric vehicle is operated using a provided operating voltage. The provided operating voltage is usually 12 V. An electric vehicle usually includes a plurality of low-voltage consumers that are operated using the provided operating voltage.

[0012] According to the present invention, during the driving of the electric vehicle in the emergency operation mode, the power motor of the electric vehicle operates as a low-voltage generator, and the low-voltage power electronic device connected to the power motor provides an operating voltage for the low-voltage electrical equipment of the electric vehicle. The emergency operation mode ensures that when the electric vehicle is driving passively / unpowered, that is, without the power torque generated by the electric vehicle, the low-voltage electrical equipment operates using the electrical energy provided by the power motor. As long as the electric vehicle is driving passively, the operation of the low-voltage electrical equipment is ensured because the power motor operates as a low-voltage generator.

[0013] It is important to note that the low-voltage battery of the electric vehicle is not required in principle in the emergency operating mode, because the power motor continuously supplies electrical energy to the low-voltage electrical devices when the electric vehicle is driven passively.

[0014] In one embodiment, the high-voltage battery of the electric vehicle provides an operating voltage for the power motor of the electric vehicle, and the power motor is operated as a power device in a normal operating mode using the provided operating voltage during driving, and when the high-voltage battery fails during driving, the power motor switches from the normal operating mode to the emergency operating mode. When the high-voltage battery fails, for example due to a technical failure or accident of the electric vehicle, the normal operation of the power motor can no longer be maintained and the power motor immediately switches to the emergency operating mode. In the normal operating mode, a DC-DC converter connected to the high-voltage battery and the low-voltage electrical equipment can provide an operating voltage for the low-voltage electrical equipment.

[0015] Preferably, when the high-voltage battery fails during driving, the low-voltage consumers are separated from the high-voltage battery and connected to the low-voltage power electronics. In other words, the low-voltage consumers are not connected to the high-voltage battery and the low-voltage power electronics at the same time.

[0016] Advantageously, when the operating voltage provided by the power motor drops in the emergency operating mode, the low-voltage battery of the electric vehicle provides the operating voltage for the low-voltage electrical equipment in the emergency operating mode. The low-voltage battery stores electrical energy as a buffer accumulator and provides the stored electrical energy to the low-voltage electrical equipment to compensate for the fluctuation of the operating voltage provided by the power motor. In this way, the operating voltage of the low-voltage electrical equipment is stabilized.

[0017] It is also advantageous to limit the driving speed of the electric vehicle in the emergency operating mode. Since the driving speed is limited, the low-voltage electrical equipment is protected from overvoltage.

[0018] The driving of the electric vehicle may include coasting, rolling down a slope or towing of the electric vehicle. Coasting, rolling down a slope and towing are passive driving of the electric vehicle during which the mobility of the electric vehicle is continuously maintained by the emergency operation mode.

[0019] Another subject of the present invention is a power system for an electric vehicle, the power system comprising a high-voltage power electronic device and a power motor connected to the high-voltage power electronic device. Such a power system is very common, so the present invention has a variety of feasible application solutions.

[0020] According to the present invention, the power system includes a low voltage power electronic device connected to a power motor and a high voltage power electronic device. The low voltage power electronic device is designed to provide an operating voltage for a low voltage electrical device in an emergency operation mode. The power electronic device may include a plurality of diodes and may be added to an existing power system. The power electronic device is low cost and light weight.

[0021] The low voltage power electronics can be independent of the high voltage power electronics or integrated into the high voltage power electronics.

[0022] Preferably, the power motor is designed as a separately excited synchronous motor (FSM). A separately excited synchronous motor comprises an electromagnet, which generates a magnetic field for a rotor of the synchronous motor when an excitation current flows through the electromagnet. The separately excited synchronous motor is more easily applicable to the method according to the invention due to the electromagnet. A current transmitter connected to the electromagnet can provide the electromagnet with an excitation current.

[0023] A third subject of the present invention is an electric vehicle, which includes a high-voltage battery, a power system, and low-voltage electrical equipment.

[0024] According to the present invention, the electric vehicle includes a low-voltage power electronic device of a power system according to one embodiment of the present invention, the power system is connected to a high-voltage battery, and the low-voltage power electronic device is functionally connected to a low-voltage electrical device. Of course, the electric vehicle also includes a power system. In the event that the high-voltage battery fails during the driving of the electric vehicle, the power system can implement an emergency operation mode of the power motor, which supports the operation of the low-voltage electrical device without the participation of the high-voltage battery.

[0025] Preferably, the low-voltage electrical equipment is designed as a wire-controlled steering system and / or a wire-controlled brake of an electric vehicle. When the power motor provides operating voltage for the wire-controlled steering system or the wire-controlled brake in the emergency operation mode, the electric vehicle can still maintain maneuverability in the event of a high-voltage battery failure. For example, a steering system compatible with the ECE R-79 protocol can be provided in this way.

[0026] The method according to the invention has the advantage that it enables long-term operation of low-voltage loads in the event of a failure of the high-voltage battery and can be implemented cost-effectively without significantly increasing the mass of the electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention is schematically illustrated according to the embodiments in the accompanying drawings and is described in detail with reference to the accompanying drawings, in which:

[0028] Figure 1 A circuit diagram showing a portion of an electric vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] Figure 1 A circuit diagram shows a part of an electric vehicle 1 according to an embodiment of the present invention. The electric vehicle 1 includes one low-voltage electrical device 11 or multiple low-voltage electrical devices 11. The low-voltage electrical device 11 can be designed as a wire-controlled steering system of the electric vehicle 1 or a wire-controlled brake of the electric vehicle 1. In addition, the electric vehicle 1 can include a low-voltage battery 12 connected to the low-voltage electrical device 11.

[0030] In addition, the electric vehicle 1 includes a low-voltage power electronic device 102 functionally connected to the low-voltage electrical equipment 11 of the power system 10 according to an embodiment of the present invention. The power system 10 is suitable for the electric vehicle 1, and the power system belongs to the electric vehicle 1 and includes a high-voltage power electronic device 100, a power motor 101 connected to the high-voltage power electronic device 100, and a low-voltage power electronic device 102 connected to the power motor 101 and the high-voltage power electronic device 100. The power motor 101 can be designed as a separately excited synchronous motor (FSM). The power system 10 may also include a current sensor 103 connected to the power motor 101 and / or a high-voltage battery 104 connected to the power electronic device 100.

[0031] The power system is designed to operate low-voltage electrical consumers 11 of the electric vehicle 1 and implements the method according to the embodiment of the present invention in the following manner.

[0032] The high-voltage battery 104 of the electric vehicle 1 can provide an operating voltage for the power motor 101 of the electric vehicle 1, or more precisely, for the high-voltage power electronic device 100. During driving, in a normal operating mode, the power motor 101 can be operated as a drive motor using the provided operating voltage. If the high-voltage battery 104 fails during driving, the power motor 101 can be switched from the normal operating mode to the emergency operating mode.

[0033] When the electric vehicle 1 is running in the emergency operation mode, the power motor 101 of the electric vehicle 1 is operated as a low-voltage generator. The running of the electric vehicle 1 includes, for example, coasting of the electric vehicle 1 , rolling down a slope of the electric vehicle 1 , or towing of the electric vehicle 1 .

[0034] The low-voltage power electronics device 102 connected to the power motor 101 provides an operating voltage for the low-voltage electrical consumers 11 of the electric vehicle 1. The low-voltage electrical consumers 11 are operated using the provided operating voltage in the emergency operation mode.

[0035] Preferably, if the high-voltage battery 104 fails during driving, the low-voltage consumers 11 are disconnected from the high-voltage battery 104 and the low-voltage consumers are connected to the low-voltage power electronics 102 .

[0036] In addition, if the operating voltage provided by the power motor 101 drops in the emergency operating mode, the low-voltage battery 12 of the electric vehicle 1 can provide the operating voltage for the low-voltage electrical equipment 11 in the emergency operating mode.

[0037] Ideally, the driving speed of the electric vehicle 1 is limited in the emergency operating mode.

[0038] List of reference numerals:

[0039] 1 Electric Vehicles

[0040] 10 Powertrain

[0041] 100 High Voltage Power Electronics Devices

[0042] 101 Power Motor

[0043] 102 Low voltage power electronics equipment

[0044] 103 Current transmitter

[0045] 104 High Voltage Battery

[0046] 11 Low voltage electrical equipment

[0047] 12 Low voltage battery

Claims

1. A method for operating a low-voltage electrical consumer (11) of an electric vehicle (1), It is characterized in that - During the driving of the electric vehicle (1) in the emergency operation mode, the power motor (101) of the electric vehicle (1) operates as a low-voltage generator, and the low-voltage power electronic device (102) connected to the power motor (101) provides an operating voltage for the low-voltage electrical equipment (11) of the electric vehicle (1); - In the emergency operation mode, the low-voltage electrical equipment (11) is operated using the provided operating voltage.

2. The method according to claim 1, characterized in that A high-voltage battery (104) of an electric vehicle (1) provides an operating voltage for a power motor (101) of the electric vehicle (1); the power motor (101) is operated as a power device in a normal operating mode using the provided operating voltage during driving; when the high-voltage battery (104) fails during driving, the power motor (101) is switched from the normal operating mode to the emergency operating mode.

3. The method according to claim 2, characterized in that When the high-voltage battery (104) fails during driving, the low-voltage electric device (11) is separated from the high-voltage battery (104) and connected to the low-voltage power electronic device (102).

4. The method according to any one of claims 1 to 3, characterized in that When the operating voltage provided by the power motor (101) drops in the emergency operating mode, the low-voltage battery (12) of the electric vehicle (1) provides the operating voltage for the low-voltage electrical equipment (11) in the emergency operating mode.

5. The method according to any one of claims 1 to 4, characterized in that The travel speed of the electric vehicle (1) is limited in the emergency operation mode.

6. The method according to any one of claims 1 to 5, characterized in that The driving of the electric vehicle (1) includes the gliding of the electric vehicle (1), the rolling of the electric vehicle (1) on a slope, or the towing of the electric vehicle (1).

7. A power system (10) for an electric vehicle (1), characterized in that: The power system comprises a high-voltage power electronic device (100), a power motor (101) connected to the high-voltage power electronic device (100), and a low-voltage power electronic device (102) connected to the power motor (101) and the high-voltage power electronic device (100).

8. The power system according to claim 7, characterized in that: The power motor (101) is designed as a separately excited synchronous motor, namely, a FSM.

9. An electric vehicle (1), characterized in that: The electric vehicle comprises a high-voltage battery (104), a low-voltage electrical consumer (11) and a low-voltage power electronic device (100) of a power system (10) according to claim 7 or 8, wherein the low-voltage power electronic device is functionally connected to the low-voltage electrical consumer (11), and the power system is connected to the high-voltage battery (104).

10. The electric vehicle according to claim 9, characterized in that: The low-voltage electrical device (11) is designed as a steer-by-wire system of the electric vehicle (1) and / or a brake-by-wire system of the electric vehicle (1).

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