DE102017200623A1 - Battery charge management system for a vehicle - Google Patents

Abstract

OBJECTIVE To provide a battery charge management system for a vehicle that is capable of reducing a sense of discomfort that may result to the vehicle occupant. [Solution] It is determined whether a difference in battery voltage between two batteries, i. H. a lead-acid battery and a lithium-ion battery, not less than a predetermined value THv or not (at step S1). If the difference between the two batteries is not smaller than the predetermined value THv, the electric load applied to the lead-acid battery is increased (at step S2). When the difference in the battery voltage between the two batteries is smaller than the predetermined value THv, the two batteries are connected (at step S3).

Description

[Technical area]

The present invention relates to a battery charge management system for a vehicle.

[Prior Art]

A vehicle including a hybrid powertrain includes a traction battery or a battery pack used in an electric vehicle (EV) mode, and has at least a power supply battery for supplying power to electric loads or electrical loads , To supply a current to the loads, two different types of batteries can be used.

JP 2014-033571 A discloses a system including two different types of batteries for supplying power to electrical loads and including a connection switch provided to interrupt an electrical connection between the batteries.

[State of the art]

[Patent Literature]

• Patent Literature 1: JP 2014-033571A

[Brief Description of the Invention]

[Technical problem]

At the in JP 2014-033571 A described power supply system consists in the state in which the connection switch breaks the electrical connection between the power supply batteries to allow each of the batteries provides an isolated power supply to the associated loads, a difference in the terminal voltage (or the battery voltage) between the batteries. Due to the difference, an abrupt change in the battery voltage occurs when the electrical connection between the batteries is allowed when the connection switch is in the on state.

Since the power supply to the loads changes when the abrupt change of the battery voltage occurs, a change in the brightness of the lighting and a change in the noise of the fan (fans) occur. Sometimes, such changes create a sense of discomfort for a vehicle occupant.

An object of the present invention is to reduce a change in the brightness of the lighting and a change in the noise of a fan (fans), which are powered by a battery to reduce a feeling of discomfort, possibly for results in a vehicle occupant.

[Solution to the problem]

According to one aspect, there is provided a battery charge management system for a vehicle having two batteries with different charging characteristics, the battery charge management system comprising: a load control section configured to control the amount of electrical load applied to at least one of the two batteries is applied; and a connection switch that enables an electrical connection between the two batteries or breaks the electrical connection, wherein the load control section in the case of a request for electrical connection between the two batteries, when a difference in battery voltage between the two batteries is not less than is given value allows the electrical connection between the two batteries after the amount of electrical load has been gradually varied until the difference in the battery voltage between the two batteries becomes smaller than the predetermined value.

Advantageous Effect of the Invention

According to the present invention, there is provided a battery charge management system capable of reducing a feeling of discomfort possibly to a vehicle occupant.

[Brief Description of the Drawings]

1 FIG. 12 is a diagram of a vehicle illustrating a battery charge management system; FIG.

2 Fig. 10 is a flowchart illustrating an algorithm for battery connection processes;

3 FIG. 10 is a flowchart illustrating an algorithm for battery charging; FIG.

4 Fig. 10 is a timing diagram illustrating battery connection processes;

5 is a diagram of a timing that represents a battery charging process.

[Description of an Embodiment (of Embodiments)]

Referring to the accompanying drawings, a vehicle is described with equipped with a battery charge management system.

As in 1 shown includes a vehicle 1 an engine 2 the type of an internal combustion engine, an integrated starter generator (ISG) 3 , general loads 4 , important loads 5 , a lead-acid battery 6 , a battery pack 7 and an internal combustion engine control module (ECM) 8th ,

The internal combustion engine 2 is formed with a plurality of cylinders. The present example is the internal combustion engine 2 a four-stroke engine, which means that four piston strokes are necessary to complete one cycle. The cycle includes four different processes: intake stroke, compression stroke, power stroke and exhaust stroke.

The ISG 3 is via a belt or the like with an output shaft of the internal combustion engine 2 connected. The ISG 3 When energized, it functions as an electric motor, and functions as a generator of an electric current, and generates torque from the drive wheel (s) or the internal combustion engine upon receipt of torque 2 a stream.

For general loads 4 These are electrical loads that allow variation in the supply of electrical current. The general loads 4 include, for example, a blower fan 10 ; a radiator fan 11 that is the cooling water for the internal combustion engine 2 cools; an electric water pump 12 that causes the cooling water in the internal combustion engine 2 circulates; an electric vacuum pump 13 generating a vacuum used to generate power assistance to a brake system; as well as an interior lighting 14 ,

For important loads 5 These are electrical loads that require a stable supply of electrical current. The important loads 5 include, for example, a navigation system 20 ; an audio system 21 ; a measuring instrument (measuring instruments) 22 ; a control panel 23 for a vehicle air conditioner; (a) vehicle headlight 24 ; a steering angle sensor 25 ; as well as an on-board camera 16 ,

For the lead-acid battery 6 it is a rechargeable secondary battery, which has a voltage of 12 volts. The lead-acid battery 6 is with the general loads 4 connected to the general loads 4 constantly supplying an electric current. The lead-acid battery 6 leads the ISG 3 an electric current when the ISG 3 to act as an electric motor, and it becomes by means of the ISG 3 recharged when the ISG 3 should act as a generator for an electric current.

The battery pack 7 includes a lithium ion battery 30 ; switch 31 . 32 and 33 , a connection switch 34 ; and a battery management system (BMS) 35 , The battery pack 7 has an input end 36 and an exit end 37 on.

The entrance end 36 is over a fuse 38 with the general loads 4 and the lead-acid battery 6 connected. The exit end 37 is with the important loads 5 connected. The exit end 37 includes a first connection 37a , a second connection 37b and a third connection 37c , The first connection 37a is for a connection with the important loads 5 released when the switch 31 in the on state. The second connection 37b is for a connection with the important loads 5 released when the switch 32 is in the on state, with the switch 31 in the on state. The third connection 37c is for a connection with the important loads 5 released when the switch 33 is in the on state, with the switch 31 in the on state.

With the lithium ion battery 30 it is a rechargeable secondary battery, which has a voltage of 12 volts. The vehicle 1 is equipped with a motor generator, not shown. A battery that provides electrical power to the motor generator is another lithium-ion battery that has a voltage of 100 volts.

In the following description will be the lead-acid battery 6 and the lithium ion battery 30 also referred to as "two batteries". The lithium ion battery 30 has a voltage sensor 39 on.

Under the control of the BMS 35 becomes the switch 31 put in the on state or the off state. When the switch 31 in the off state is the lithium ion battery 30 from the entrance end 36 and the exit end 37 completely separated. When the switch 31 in the on state is the lithium ion battery 30 both with the input end 36 as well as with the exit end 37 connected.

Under the control of the BMS 35 becomes the switch 32 in response to the condition of an accessory switch 40 , which will be referred to simply as "ACC" in the following description, put in the on-state or the off-state. When the switch 31 or the switch 32 in the off state is the lithium ion battery 30 from the second port 37b completely separated.

When the switches 31 and 32 in the on state is the lithium ion battery 30 with the second connection 37b connected, what the supply of a current to that proportion of the important loads 5 which is to be activated when the ACC 40 in the on state.

Under the control of the BMS 35 becomes the switch 33 in response to the condition of an ignition switch 41 , which will be referred to simply as "IG" in the following description, put in the on state or the off state. When the switch 31 or the switch 33 in the off state is the lithium ion battery 30 from the third port 37c completely separated.

When the switches 31 and 33 in the on state is the lithium ion battery 30 with the third connection 37c which allows the supply of a current to that portion of the important loads to be activated when the IG 41 in the on state.

The connection switch 34 allows an electrical connection between the two batteries 6 and 30 which differ in charging characteristics or interrupts this electrical connection. Under the control of the BMS 35 becomes the connection switch 34 in response to instructions from the ECM 8th put in the on state or the off state.

When the switch 31 or the connection switch 34 in the off state are the lead-acid battery 6 and the lithium ion battery 30 completely separated. When the switch 31 and the connection switch 34 are in the ON state, are the lead-acid battery 6 and the lithium ion battery 30 connected in parallel. The present example is explained, wherein the switch 31 normally in on-state.

In the present example, the BMS exists 35 a computer unit including a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), a flash memory for a data backup, input terminals and output terminals.

The ROM of this computer unit stores programs in addition to various constants and various maps to cause the computer unit to function as the BMS 35 acts. In other words, it causes the computer unit as the BMS 35 by allowing the CPU to execute programs stored in the ROM using the RAM as a workspace.

The BMS 35 Connects to other controllers, such as the ECM, through a local area network (LAN) that meets Controller Area Network (CAN) or FlexRay standards and is connected to a network module 8th ,

In the present example, the BMS controls 35 the on / off switching between the on state and the off state of each of the switches 31 . 32 and 33 and the connection switch 34 in response to the states of the ACC 40 and the IG 41 and the instructions from the ECM 8th ,

In the present example, the ECM exists 8th a computer unit including a CPU, a RAM, a ROM, a flash memory for backup, input terminals and output terminals.

The ROM of this computer unit stores programs in addition to various constants and various maps to cause the computer unit to function as the ECM 8th acts. In other words, it causes the computer unit to act as the ECM 8th by allowing the CPU to execute programs stored in the ROM using the RAM as a workspace. The ECM 8th Connects to other network controllers, such as the BMS, via LAN, which is connected to the network module 35 ,

In the present example are sensors that are for the internal combustion engine 2 and the ISG 3 are provided with the input terminals of the ECM 8th connected. The output terminals of the ECM 8th are with every section of the internal combustion engine 2 and connected to each of the objects to be controlled, such as the ISG 3 and the general loads.

The ECM 8th controls the various objects to be controlled and the other control units, such as the BMS 35 Based on information provided by various sensors and the other control units, such as the BMS 35 , receives.

In the present example, the ECM functions 8th as a voltage sensor 50 , which is a terminal voltage of the lead-acid battery 6 detected, as well as a load control section 51 which controls the amount of load applied to each of the two batteries.

In the case of a request for an electrical connection between the two batteries 6 and 30 , enables the ECM 8th if a difference in battery voltage (ie the terminal voltage) between the two batteries 6 and 30 not smaller than a predetermined value THv is the electrical connection between the two batteries 6 and 30 After gradually varying the amount of electrical load, the difference in battery voltage between the two batteries 6 and 30 becomes smaller than the predetermined value THv. The predetermined value THv is determined experimentally.

In the electric vehicle (EV) mode, when the vehicle 1 is powered solely by the motor generator is the internal combustion engine 2 shut off, and the electrical connection between the two batteries 6 and 30 is interrupted. During this period of operation, the lead acid battery 6 a current only for the general loads 4 ready, and the lithium-ion battery 30 provides a current only for the important loads 5 ready.

The process of an electrical connection between the two batteries 6 and 30 and the process that the battery is recharged by the ISG 3 is operated when the internal combustion engine 3 is restarted by factors such as a decrease in residual battery capacity, a need for operation of a vehicle air conditioning system, and a need for warm-up. If a difference in battery voltage between the two batteries 6 and 30 is not smaller than the predetermined value THv, increases the ECM 8th gradually the amount of electrical load that matches that of the two batteries 6 and 30 is applied, which has a battery voltage which is higher than that of the other battery to bring the battery voltage of one battery close to the battery voltage of the other. The ECM 8th increases the amount of electrical load at such a gradual rate that falls within a range that gives a slight conspicuous feeling to the driver of the vehicle. This scope will be in advance in the ROM of the ECM 8th saved.

The ECM 8th determines, for example, whether a difference in the battery voltage between a detection value of the voltage sensor 50 and a detection value of the voltage sensor 39 is not smaller than the predetermined value THv or not, that is, whether there is a difference in the battery voltage between the two batteries 6 and 30 is not smaller than the predetermined value THv or not. The ECM 8th increases the electrical load connected to the lead-acid battery 6 by applying the dimension of driving the general loads 4 , such as the radiator fan 11 , the electric water pump 12 and the electric vacuum pump 13 , gradually varies until the difference in battery voltage between the two batteries 6 and 30 becomes smaller than the predetermined value THv.

The ECM 8th has the BMS 35 on, the connection switch 34 put into the on state at a time when the difference in battery voltage between the two batteries 6 and 30 becomes smaller than the predetermined value THv.

The ECM 8th acts as a power generation control section 52 , which is a power generation torque of the ISG 3 controls. The ECM 8th At times, the increase rate at which the power generation torque varies while the increase rate is kept within a predetermined value range is changed periodically when the ISG is caused to change 3 generates a current.

After making the electrical connection between the two batteries 6 and 30 become the two batteries 6 and 30 charged with a current from the ISG 3 is produced. The ECM 8th increases the power generation torque by periodically combining a period of time when the rate of change is low and a time period when the rate of change is high until the battery voltage of the lead-acid battery 6 and those of the lithium ion battery 30 take their setpoints. The ECM 8th The amount of electrical load varies at such a gradual rate that falls within an extent that gives a slight conspicuous feeling to the driver of the vehicle. This scope will be in advance in the ROM of the ECM 8th saved.

The ECM 8th For example, it periodically increases the power generation torque of the ISG 3 in that each time period is subdivided into a first partial period T1 and a second partial period T2. The second sub-period T2 is longer than the first sub-period T1.

The ECM 8th controls the increase rate such that the power generation torque of the ISG 3 during the first sub-period T1 is increased at a first rate of increase d1 and increased during the second sub-period T1 at a second rate of increase. The second increase rate T2 is lower than the first increase rate T1. The first partial period T1, the second partial period T2, the first increase rate d1, and the second increase rate d2 are predetermined values.

Referring to 2 the operation of the battery charge management system for enabling the electrical connection between the lead-acid battery 6 and the lithium ion battery 30 or for interrupting this electrical connection. The operation of the operation described below is repeated until the operation of connecting the two batteries 6 and 30 is finished after the internal combustion engine 2 was restarted.

At step S1, it is determined whether there is a difference in the battery voltage between the two batteries 6 and 30 is not smaller than the predetermined value THv or not, that is, whether or not (V _Pb -V _Li )> THv, where V _{Pb is} the battery voltage of the lead-acid battery 6 is that of the voltage sensor 50 is detected, and V _{Li is} the battery voltage of the lithium-ion battery 30 is that of the voltage sensor 39 is detected. This provision may be by the ECM 8th be performed.

If it is determined at step S1 that V _Pb - V _{Li is} not smaller than THv, then the algorithm advances to step S2. If V _Pb - V _{Li is} less than THv at step S1, then the algorithm advances to step S3.

At step S2, an electrical load is added to the lead-acid battery 6 created (or worn by) is. After step S2, the algorithm returns to step S1. At step S3, an electrical connection between the two batteries 6 and 30 allows. An increase in electrical load and electrical connection may be under the control of the ECM 8th be performed.

Referring to 3 describes processes of the battery charge management system with respect to a charging process. The operation described below is repeated until the charging of the battery is completed after the electrical connection between the two batteries 6 and 30 was possible.

At step S11, the ISG is caused to be 3 power generation starts when the ISG is not generating power. After step S11, the algorithm advances to step S12. The processes performed at step S11 may be performed by the ECM 8th be performed.

At step S12, it is determined whether or not the present state exists during the first split period T1. If it is determined at step S12 that the present state exists during the first sub-period T1, then the algorithm advances to S13. If, at step S12, the present state is not present during the first sub-period T1 (or in other words, if the present state exists during a second sub-period T2, T1 <T2), then the algorithm advances to step S14. The determination may be made by the ECM 8th be performed.

At step S13, the power generation torque is given by the ISG 3 increases with a first rate of increase d1. After step S13, the algorithm returns. After step S13, the algorithm returns. At step S14, the power generation torque is given by the ISG 3 increases with a second rate of increase d2, where d2 <d1. After step S14, the algorithm returns.

The internal resistance of the lithium ion battery 30 is lower than that of the lead-acid battery 6 so that the former has a higher charging power than the latter. Such is the charging of the lithium ion battery 30 before the end of charging the lead-acid battery 6 stopped when charging the batteries is running when the two batteries 30 and 6 are connected.

Therefore, if it is determined that charging the lithium ion battery 30 finished, the ECM declares 8th the BMS 35 on, the connection switch 34 to put in the off state. When charging the lead-acid battery 6 is terminated, it is subsequently arranged that the ISG 3 the power generation stops.

Referring to 4 the operation of the battery charge management system for enabling the electrical connection between the lead-acid battery 6 and the lithium ion battery 30 or interrupting this electrical connection further described.

At time t1 is the internal combustion engine 2 drove down and the vehicle 1 is powered solely by the motor generator. Thereafter, at time t2, it is determined that at least one of the lead-acid battery 6 and the lithium ion battery 30 requires recharging, and immediately after time t2 becomes the measure of the general load 4 varies in stages to the difference in battery voltage between the two batteries 6 and 30 ie to decrease V _Pb - V _Li so that it becomes smaller than the predetermined value THv.

At time t3, the internal combustion engine becomes 2 started. At time t4, the difference in voltage between the two batteries 6 and 30 less than the predetermined value THv, BMS 35 is from the ECM 8th instructed the connection switch 34 to put in the on-state to the electrical connection between the lead-acid battery 6 and the lithium ion battery 30 to enable.

Referring to 5 For example, processes for charging the battery charge management system are described.

At time t4 are the lead-acid battery 6 and the lithium ion battery 30 Then, at time t5, charging of the lead-acid battery begins 6 and the lithium ion battery 30 , Until the time t6 after the time t5, ie until the lapse of the first partial period T1, the ISG 3 the power generation torque increases at the first increase rate d1. To At the time t7 after the time t6, that is, until the elapse of the second partial period T2, the ISG is caused to be 3 the power generation torque increases at the second increase rate d2.

Until the time t8 after the time t7, ie until the lapse of the first partial period T1, the ISG 3 the power generation torque increases at the first increase rate d1. Until the time t9 after the time t8, ie until the lapse of the second partial period T2, the ISG is caused to be active 3 the power generation torque increases at the second increase rate d2.

As described, the power generation torque of the ISG 3 varies periodically, with the rate of increase being maintained within the predetermined range. When charging the lithium ion battery 30 is finished, then then the connection switch 34 put in the off state. When charging the lead-acid battery 6 is terminated, after that causes the ISG 3 the power generation stops.

As apparent from the above description, in the present embodiment, the voltage applied to the electric loads is prevented from rapidly changing when the two batteries 6 and 30 get connected. Therefore, this reduces a change in the brightness in the lighting and a change in the noise of a fan (of fans), thereby reducing a feeling of discomfort that may result to the vehicle occupant.

Moreover, in the present embodiment, the amount of power generation in the present embodiment can reach the target power generation amount in a shorter time because the power generation torque is increased, and the increase rate is changed periodically.

Furthermore, a change in brightness in the lighting and a change in the noise of a fan (s) may be reduced to such an extent that the vehicle occupant does not feel such changes.

In the present example, the embodiment will be described on the assumption that V _{Pb is} higher than V _Li . When V _{Pb is} lower than V _Li , the battery voltage of the lead-acid battery, ie, V _Pb , becomes the ECM 8th increases by increasing the drive level provided by the ISG 3 is produced.

In the present example, the ISG is used as a power generator. The embodiment may use an alternator or the like as such a power generator.

Although the embodiments of the present invention have been described, it will be apparent to those skilled in the art that modifications may be made without departing from the scope of the present invention. All such modifications and equivalents thereof are intended to be covered by the following claims, which are described in the scope of the claims.

LIST OF REFERENCE NUMBERS

1

Hybrid electric vehicle

3

integrated starter generator (ISG) (generator)

4

general load (electrical load)

6

Lead-acid battery (battery)

34

connecting switches

39

voltage sensor

50

voltage sensor

51

Load control section

52

Power generation control section

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2014-033571 A [0003, 0005]

Claims (2)

A battery charge management system for a vehicle having two batteries with different charging characteristics, the battery charge management system comprising: a charge control section configured to control the amount of electrical load applied to at least one of the two batteries; and a connection switch which allows an electrical connection between the two batteries or interrupts the electrical connection, wherein, in the case of a request of the electrical connection between the two batteries, when a difference in the battery voltage between the two batteries is not smaller than a predetermined value, the charging control section enables the electrical connection between the two batteries after the amount of electric power Load was gradually varied until the difference in battery voltage between the two batteries becomes smaller than the predetermined value. A battery charge management system according to claim 1, further comprising: a power generator; and a power generation control section configured to control the power generation torque by the power generator; wherein the power generation control section periodically varies the power generation torque, wherein the increase rate in the case of a power generation request by the power generator is kept within the predetermined range.

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