Method for controlling a battery-electric drive system for a motor vehicle

Abstract

The invention relates to a method for controlling a battery-electric drive system for a motor vehicle, wherein the battery-electric drive system comprises a high-voltage battery (1), at least one electric traction drive motor (2) and a plurality of electrical auxiliary loads (3), and the at least one electric traction drive motor (2) and the electrical auxiliary loads (3) are supplied with electric power from the high-voltage battery (1), comprising the following steps: • - detecting a present state of charge and / or a present battery current limit value of the high-voltage battery (1), • - reducing the drive power of the at least one electric traction drive motor (2) and / or switching off electrical auxiliary loads (3) on the basis of the detected present state of charge and / or the detected present battery current limit value. In line with the method according to the invention, a specific priority is assigned to each electrical auxiliary load (3) and the electrical auxiliary loads (3) are switched off or power consumption by the electrical auxiliary loads (3) is reduced on the basis of the detected present state of charge and / or the detected present battery current limit value individually depending on the specific priority of the respective electrical auxiliary load (3), so that electrical auxiliary loads (3) with a comparatively higher specific priority are switched off, or the power consumption by these electrical auxiliary loads is reduced, with a lower priority than electrical auxiliary loads (3) with a comparatively lower specific priority.

Description

[0001] Method for controlling a battery-electric drive system for a motor vehicle

[0002] The present invention relates to a method for controlling a battery-electric drive system for a motor vehicle according to the preamble of claim 1.

[0003] In vehicles with battery-electric drive systems, both the at least one electric traction drive motor and various electrical auxiliary consumers are supplied with electrical power from a high-voltage battery, hereinafter referred to as the HV battery. When the HV battery reaches a certain state of charge or when the current limits of the HV battery are reached, the drive power of the at least one electric traction drive motor can be reduced, or electrical auxiliary consumers can be switched off, for example by the driver, in order to increase the remaining range of the vehicle or to reduce the load on the HV battery.

[0004] The present invention is based on the objective of providing a method for controlling a battery-electric drive system for a motor vehicle, in particular for a bus, in which the electric range is increased as much as possible without significant restriction of driving performance.

[0005] The problem according to the invention is solved by a method with the features of claim 1. The dependent claims describe advantageous and particularly expedient embodiments of the invention.

[0006] According to the inventive method for controlling a battery-electric drive system for a motor vehicle, in particular for a bus, wherein the battery-electric drive system comprises an HV battery, at least one electric traction drive motor and a plurality of electrical auxiliary consumers, and the at least one electric traction drive motor and the electrical auxiliary consumers are supplied with electrical power from the HV battery, the following steps are comprised:

[0007] Determining the current state of charge and / or the current battery current limit of the HV battery;

[0008] Reducing the drive power of at least one electric traction drive motor and / or switching off electrical auxiliary consumers depending on the detected current state of charge and / or the current battery current limit.

[0009] According to the invention, each electrical auxiliary consumer is assigned a specific priority, and the switching off of the electrical auxiliary consumers or a reduction in the power consumption of the electrical auxiliary consumers takes place depending on the detected current state of charge and / or the current battery current limit value, individually depending on the specific priority of the respective electrical auxiliary consumer, so that electrical auxiliary consumers with a comparatively higher specific priority are switched off or have their power consumption reduced in a subordinate manner to electrical auxiliary consumers with a comparatively lower specific priority.

[0010] The battery current limit value represents the maximum current that the HV battery can or should currently deliver, for example to avoid unwanted heating or damage to the HV battery.

[0011] The invention makes it possible to first switch off or reduce the power consumption of electrical auxiliary consumers whose shutdown or reduction in power consumption results in no or only a minor loss of comfort for the vehicle powered by the battery-electric drive system. Only if this power reduction or shutdown is insufficient are further measures taken in the form of switching off or reducing the power consumption of electrical auxiliary consumers with higher priority and / or reducing the power consumption of the at least one electric traction drive motor.

[0012] According to a preferred embodiment of the invention, the electrical auxiliary consumers are divided into groups with identical specific priorities and are switched off or their power consumption is reduced in groups.

[0013] In particular, an electrical auxiliary consumer or a group of electrical auxiliary consumers with a first specific priority, namely a low priority, is switched off immediately as soon as the detected current state of charge has fallen to a first predetermined state of charge limit and / or the detected current battery current limit has fallen to a predetermined first value.

[0014] The electrical auxiliary consumers with the first specific priority include, for example, one or more of the following electrical auxiliary consumers:

[0015] Components for passenger compartment heating, seat heating and / or steering wheel heating;

[0016] Passenger compartment air conditioning units;

[0017] Passenger compartment lighting components;

[0018] Components of an entertainment system;

[0019] Components of an infotainment system.

[0020] According to a further development of the invention, an electrical auxiliary consumer or a group of electrical auxiliary consumers with a second specific priority reduces its electrical power consumption as soon as the detected current state of charge has fallen to a predetermined state of charge limit compared to the first, smaller second value and / or the detected current battery current limit has fallen to a predetermined value compared to the first, smaller second value.

[0021] The reduction of the electrical power consumption of the electrical auxiliary consumers with the second specific priority is particularly variable, for example down to zero, depending on the detected current state of charge and / or the detected current battery current limit.

[0022] For example, the electrical auxiliary consumers with second specific priority include one or more of the following electrical auxiliary consumers:

[0023] Components of an on-board power supply; a control unit for an auxiliary power steering pump.

[0024] In a further development of the invention, the power consumption of the at least one electric traction drive motor is adjusted according to a driver command or a specification of a vehicle assistance system, as long as the detected current state of charge has not fallen to a third predetermined state of charge limit and / or the detected current battery current limit has not fallen to a predetermined third value, wherein the third predetermined state of charge limit is smaller than the second predetermined state of charge limit and the third predetermined value is smaller than the second predetermined value, and as soon as the detected current state of charge limit has fallen to the third predetermined state of charge limit and / or the detected current battery current limit has fallen to the third predetermined value, the power consumption of the electric traction drive motor is reduced.According to a further development of the invention, an electrical auxiliary consumer or a group of electrical auxiliary consumers with a third specific priority is switched off or its power consumption is reduced as soon as the detected current state of charge has fallen to a predetermined fourth state of charge limit, which is smaller than the predetermined third state of charge limit, and / or the detected current battery current limit has fallen to a predetermined fourth value, which is smaller than the predetermined third value.

[0025] The electrical auxiliary consumers with the third specific priority include, for example, one or more of the following electrical auxiliary consumers:

[0026] Compressed air supply units for motor vehicles;

[0027] Components of a vehicle's exterior lighting system;

[0028] Components of a vehicle braking system.

[0029] According to an advantageous embodiment of the invention, the specific priorities of the electrical auxiliary consumers are variably adjustable, in particular by a fleet operator who provides a large number of motor vehicles with a corresponding battery-electric drive system, or by workshop personnel.

[0030] According to the invention, the power consumption of auxiliary units and / or the at least one electric traction drive motor can be dynamically limited when the driving performance, in combination with the power demand of the electrical auxiliary consumers, exceeds a battery limit. As soon as the total power demand decreases again, the temporary limitations can be partially or completely lifted. Hysteresis can be implemented when switching electrical auxiliary consumers on and off to prevent constant switching of the affected electrical auxiliary consumers.

[0031] The invention will below be described by way of example using an embodiment and the figure.

[0032] Figure 1 shows a battery-electric drive system according to the invention for a motor vehicle, for example, a bus, comprising a high-voltage battery 1, an electric traction drive motor 2, and a plurality of electrical auxiliary consumers 3. The high-voltage battery 1, the electric traction drive motor 2, and the electrical auxiliary consumers 3 are connected to a power distribution unit 5, also called a power distribution box (PDB) or power distribution unit (PDU), which controls the electrical power flows in the battery-electric drive system. A charging port is also connected to the power distribution unit 5, which enables unidirectional or bidirectional charging of the high-voltage battery 1.

[0033] For example, the secondary consumers 3 are divided into three groups I, II, III. Each group I, II, III, or each secondary consumer 3 within a group I, II, III, is assigned a specific priority, whereby the specific priorities of the secondary consumers 3 within a common group I, II, III are identical.

[0034] Since the high-voltage (HV) battery is discharged during vehicle operation, its current state of charge decreases, except during recuperation phases. Furthermore, the HV battery 1 has a current limit that cannot be exceeded. Accordingly, the total power output currently possible from the HV battery 1 is limited. According to the invention, the total power demand, which comprises the power demand of the electrical auxiliary consumers 3 and the electric traction drive motor 2, is limited if it exceeds the power available from the HV battery 1. According to the invention, the power demand of the electrical auxiliary consumers 3 and the electric traction drive motor 2 is individually limited.

[0035] The electrical auxiliary consumers 3 of the first group I are assigned a comparatively low, first specific priority, which results in these electrical auxiliary consumers 3 of the first group I being switched off immediately when the detected state of charge of the HV battery 1 reaches or falls below a first predetermined state of charge limit and / or the detected current battery current limit has fallen to or below a predetermined first value.

[0036] The electrical auxiliary consumers 3 in the first group I include, for example, units for passenger compartment heating, other heated interior equipment such as seat and / or steering wheel heating, units for passenger compartment air conditioning, units for passenger compartment lighting, units for an entertainment system and / or units for an infotainment system.

[0037] If the current state of charge of the HV battery 1 continues to decrease and reaches a second predefined state of charge limit, and / or the battery current limit has dropped to a predefined second value, the power consumption of the electrical auxiliary consumers 3 in the second group II is limited. These electrical auxiliary consumers 3 have a second specific priority that is higher than the first specific priority.

[0038] If the current state of charge of the HV battery 1 continues to fall to a third predetermined state of charge limit and / or the current battery current limit falls to a predetermined third value, the power consumption of the electric traction drive motor 2 is limited in relation to a power demand by the driver or by a vehicle assistance system.

[0039] If the current state of charge of the HV battery 1 falls further to a fourth predetermined state of charge limit and / or the current battery current limit falls to a predetermined fourth value, the electrical power consumption of the auxiliary electrical consumer(s) 3 of the third group III is reduced or the auxiliary electrical consumer(s) 3 of the third group III is switched off. In the third group III, auxiliary electrical consumers 3 with a third specific priority that is higher than the second specific priority are grouped together, whereby only a single auxiliary electrical consumer 3 may be provided in each group I, II, and III.

[0040] The electrical auxiliary consumers 3 in the third group III are, for example, units of a compressed air supply system of the motor vehicle, units of a vehicle exterior lighting system and / or units of a vehicle braking system and / or other units that are absolutely necessary for the operation or safety of the vehicle.

[0041] Reference symbol list

[0042] 1 HV battery

[0043] 2 electric traction drive motor 3 electric auxiliary consumers

[0044] 4 charging ports

[0045] 5 Energy distribution unit

Claims

Patent claims 1. Method for controlling a battery-electric drive system for a motor vehicle, wherein the battery-electric drive system comprises an HV battery (1), at least one electric traction drive motor (2) and a plurality of electrical auxiliary consumers (3), and the at least one electric traction drive motor (2) and the electrical auxiliary consumers (3) are supplied with electrical power from the HV battery (1), comprising the following steps: Determining the current state of charge and / or current limit value of the HV battery (1 ); Reducing the drive power of the at least one electric traction drive motor (2) and / or switching off electrical auxiliary consumers (3) depending on the detected current state of charge and / or the detected current battery current limit;characterized in that each electrical auxiliary consumer (3) is assigned a specific priority and the switching off of the electrical auxiliary consumers (3) or a reduction in the power consumption of the electrical auxiliary consumers (3) is carried out individually depending on the specific priority of the respective electrical auxiliary consumer (3), depending on the detected current state of charge and / or the detected current battery current limit value, so that electrical auxiliary consumers (3) with a comparatively higher specific priority are switched off or have their power consumption reduced in a subordinate manner to electrical auxiliary consumers (3) with a comparatively lower specific priority.

2. Method according to claim 1, characterized in that the electrical auxiliary consumers (3) are divided into groups (I, II, III) with identical specific priorities and are grouped together They can be switched off together or have their power consumption reduced.

3. Method according to claim 1 or 2, characterized in that an electrical auxiliary load (3) or a group of electrical auxiliary loads (3) with a first specific priority is switched off immediately as soon as the detected current state of charge has fallen to a first predetermined state of charge limit and / or the detected current battery current limit has fallen to a predetermined first value.

4. Method according to claim 3, characterized in that the electrical auxiliary consumers (3) with the first specific priority comprise one or more of the following electrical auxiliary consumers in (3): Components for passenger compartment heating, seat and / or steering wheel heating; Passenger compartment air conditioning units; Components for passenger compartment lighting; components for an entertainment system; components for an infotainment system.

5. Method according to one of claims 3 or 4, characterized in that an electrical auxiliary consumer (3) or a group (II) of electrical auxiliary consumers (3) with a second specific priority is / are reduced in its / their electrical power consumption as soon as the detected current state of charge has fallen to a second predetermined state of charge limit value that is smaller than the first predetermined state of charge limit value and / or the detected current battery current limit value has fallen to a second predetermined value that is smaller than the predetermined first value.

6. Method according to claim 5, characterized in that the reduction of the electrical power consumption of the electrical auxiliary consumers (3) with the second specific priority is variable, in particular down to zero, depending on the detected current state of charge and / or the detected current battery current limit value.

7. Method according to one of claims 5 or 6, characterized in that the electrical auxiliary consumers (3) with the second specific priority comprise one or more of the following electrical auxiliary consumers (3): Components of an on-board power supply; a control unit for an auxiliary power steering pump.

8. Method according to one of claims 5 to 7, characterized in that the power consumption of the at least one electric traction drive motor (2) is adjusted according to a driver command or a specification of a vehicle assistance system, as long as the detected current state of charge has not fallen to a third predetermined state of charge limit value that is smaller than the second predetermined state of charge limit value and / or the detected current battery current limit value has not fallen to a predetermined third value that is smaller than the predetermined second value, and as soon as the detected current state of charge has fallen to the third predetermined state of charge limit value and / or the detected current battery current limit value has fallen to the third value, the power consumption of the at least one electric traction drive motor (2) is reduced.

9. Method according to claim 8, characterized in that an electrical auxiliary load (3) or a group (III) of electrical auxiliary loads (3) is switched off or its power consumption is reduced with a third specific priority as soon as the detected current state of charge has fallen to a fourth specified state of charge limit that is smaller than the third specified state of charge limit and / or the detected current battery current limit has fallen to a fourth specified value that is smaller than the specified third value.

10. Method according to claim 9, characterized in that the electrical auxiliary consumers (3) with the third specific priority comprise one or more of the following electrical auxiliary consumers (3): Components of a motor vehicle's compressed air supply system; components of a vehicle's exterior lighting system; Components of a vehicle braking system.

11. Method according to one of claims 1 to 10, characterized in that the specific priorities of the electrical auxiliary consumers (3) can be variably set by a fleet operator or by workshop personnel.

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