KR20200045267A - Battery pack, and dc/dc conveter control method of battery management system - Google Patents

Abstract

The present invention relates to a DC/DC converter control method of a battery management system mounted in a vehicle equipped with a first battery for driving a motor, a second battery for electric load, and a DC/DC converter connected between the first and second batteries. The DC/DC converter control method of a battery management system comprises the steps of: controlling output voltage of the DC/DC converter to first voltage as the vehicle enters a regenerative braking mode; changing an output voltage change rate of the DC/DC converter according to whether the first battery is fully charged, when the termination of the regenerative braking mode is requested; and reducing the output voltage of the DC/DC converter to second voltage based on the output voltage change rate.

Description

BATTERY PACK, AND DC / DC CONVETER CONTROL METHOD OF BATTERY MANAGEMENT SYSTEM}

Embodiments of the present invention are directed to a DC / DC converter control method of a battery pack and a battery management system.

As environmental regulations such as CO2 regulations have recently been strengthened, interest in eco-friendly vehicles has increased. Accordingly, auto companies are actively researching and developing products for pure electric vehicles or hydrogen vehicles, as well as hybrid vehicles or plug-in hybrid vehicles.

The eco-friendly vehicle is equipped with a motor driven by electricity, a main battery for driving the motor, an auxiliary battery for electric load, and a converter for charging the auxiliary battery from the main battery. In an eco-friendly vehicle, the driving motor is driven by electric energy stored in the battery to provide the driving force of the vehicle. In addition, when the vehicle needs to be decelerated, it rotates in the opposite direction to the vehicle's driving direction to decelerate the vehicle while generating back EMF to generate the battery It can also be charged. As described above, charging the battery while decelerating the vehicle using the driving motor is referred to as regenerative braking.

In an eco-friendly vehicle, a DC / DC converter is mounted between a high voltage main battery and a low voltage auxiliary battery. The DC / DC converter receives a required output voltage command from a vehicle control unit (Hybrid Control Unit, or Vehicle Control Unit), and on the basis of this, converts the high voltage output of the main battery to a required voltage to charge the auxiliary battery. Typically, the vehicle controller increases the output voltage of the DC / DC converter to store as much energy as possible in the secondary battery in the charging mode of the main battery, and DC / in order to minimize power consumption of the main battery in the discharge mode of the main battery. The output voltage of the DC converter is dropped. Therefore, the output voltage of the DC / DC converter rises while the vehicle is driving in the regenerative braking mode, and the output voltage of the DC / DC converter decreases when the regenerative braking is finished.

When the energy regeneration is maintained for a long time in a situation where there is a lot of driving or braking such as a long downhill section, a situation in which the main battery is fully charged may occur. When the main battery is fully charged, the regenerative braking should be terminated and the brake brake pads should be used to switch to the friction brake mode. The section for switching from regenerative braking to friction braking is called a torque blending section. In this torque blending section, the sum of torque due to regenerative braking and torque due to friction braking may be a braking torque felt by the driver. At this time, even with slight torque fluctuations, the driver feels jerked. Therefore, in the torque blending section, the control for the torque of the heterogeneous (異種) should be performed as precisely and smoothly as possible.

The technical problem to be solved through the embodiments of the present invention is to provide a battery pack capable of supporting smooth torque blending control at the end of regenerative braking of a vehicle, and a DC / DC converter control method of a battery management system.

A battery management system mounted on a vehicle having a first battery for driving a motor, a second battery for electric load, and a DC / DC converter connected between the first and second batteries according to an embodiment for solving the above problems In the DC / DC converter control method, as the vehicle enters the regenerative braking mode, controlling the output voltage of the DC / DC converter to a first voltage, when the termination of the regenerative braking mode is requested, the first The method may include changing an output voltage change rate of the DC / DC converter according to whether the battery is fully charged, and reducing the output voltage of the DC / DC converter to a second voltage based on the output voltage change rate. .

The changing step may include setting the rate of change of the output voltage to a first value when the first battery is in a buffer state.

The changing step may further include setting the rate of change of the output voltage to a second value that is greater than the first value when the first battery is not in a buffer state.

The DC / DC converter control method may further include determining whether the first battery is fully charged according to a state of charge of the first battery or a voltage of the first battery.

Therefore, the step of changing the rate of change of the regenerative braking torque may be further included.

In addition, a battery pack mounted in a vehicle having a first battery for driving a motor, a second battery for electric load, and a DC / DC converter connected between the first and second batteries according to an embodiment of the present invention is When entering the regenerative braking mode, the output voltage of the DC / DC converter is controlled to a first voltage, and when the termination of the regenerative braking mode is requested, the DC / DC set differently according to whether the first battery is fully charged or not. It may include a first controller for reducing the output voltage of the DC / DC converter to a second voltage based on the rate of change of the output voltage of the converter.

The first controller controls the rate of change of the output voltage to a first value when the first battery is in a buffer state when requesting the termination of the regenerative braking mode, and the first battery is in a buffer state when requesting the termination of the regenerative braking mode. Otherwise, the rate of change of the output voltage may be controlled to a second value greater than the first value.

The battery pack may further include a battery management system that determines whether the first battery is fully charged based on a state of charge of the first battery or a voltage of the first battery.

The battery pack may include the DC / DC converter.

The first controller may be a converter controller that controls the output voltage of the DC / DC converter.

The first controller may be a battery management system.

According to an embodiment of the present invention, smooth torque blending control is possible at the end of regenerative braking of the vehicle, and it is possible to prevent the battery from being overcharged in the process.

1 schematically illustrates a vehicle control system according to an embodiment of the present invention.
2A and 2B illustrate examples of controlling a braking torque of a vehicle in a vehicle control system according to an embodiment of the present invention.
3 illustrates examples of controlling an output voltage of a DC / DC converter in a vehicle control system according to an embodiment of the present invention.
4 schematically illustrates a DC / DC converter control method in a vehicle control system according to an embodiment of the present invention.

Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. Embodiments may be implemented in many different forms and are not limited to the embodiments described herein.

In order to clearly describe the embodiments, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification. Therefore, reference numbers of components used in the previous drawings can be used in the following drawings.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the embodiments are not necessarily limited to those illustrated. In the drawings, thicknesses and regions may be exaggerated to clearly represent various layers and regions.

Electrically connecting two components includes not only connecting two components directly, but also connecting two components via other components. Other components may include switches, resistors, capacitors, and the like. In the description of the embodiments, the expression “connecting” means that it is electrically connected when there is no expression of directly connecting.

Hereinafter, a vehicle control system including a battery management system and a DC / DC converter control method of the vehicle control system will be described in detail with reference to necessary drawings.

1 schematically illustrates a vehicle control system according to an exemplary embodiment of the present invention, in order to clearly describe the exemplary embodiment, parts irrelevant to the description are omitted. In addition, FIGS. 2A and 2B illustrate examples of controlling a braking torque of a vehicle in a vehicle control system according to an embodiment of the present invention, and FIG. 3 is a DC / DC converter in a vehicle control system according to an embodiment of the present invention It shows examples of controlling the output voltage of.

Referring to FIG. 1, the vehicle control system 100 according to an embodiment of the present invention includes a main battery 110, an auxiliary battery 120, a DC / DC converter 130, and a converter controller 140 ), A battery management system (BMS) 150, a vehicle controller (Hybrid Control Unit, or Vehicle Control Unit) 160, a regenerative braking system 170, and a friction braking system 180. have.

The main battery 110 is a battery for providing driving energy (electrical energy) to a driving motor (not shown) of the vehicle, and is a high voltage battery.

The auxiliary battery 120 is a battery for a vehicle's electric load, and is a low voltage battery.

The DC / DC converter 130 is connected between the main battery 110 and the auxiliary battery 120, and converts the output voltage of the main battery 110 into a charging voltage of the auxiliary battery 120. That is, the DC / DC converter 130 may convert the high voltage output of the main battery 110 to a low voltage, and then output it to the auxiliary battery 120.

The converter controller 140 may control the output voltage of the DC / DC converter 130. Here, the output voltage of the DC / DC converter 130 is determined by at least one of the converter controller 140, the BMS 150, and the vehicle controller 160, and the driving mode of the vehicle (regenerative braking mode, friction braking mode) Etc.), whether the main battery 110 is charged, the state of charge (SOC) of the main battery 110, the voltage of the main battery 110, whether it is driven based on whether or not the high voltage electric load is driven.

In the charging mode of the main battery 110, the converter controller 140 may increase the output voltage of the DC / DC converter 130 to store as much electrical energy as possible in the auxiliary battery 120. On the other hand, the converter controller 140 reduces the output voltage of the DC / DC converter 130 in the discharge mode of the main battery 110 than in the charging mode of the main battery 110, thereby consuming power of the main battery 110. Can be minimized. For example, the converter controller 140 controls the output voltage of the DC / DC converter 130 to 15V in the charging mode of the main battery 110 and the DC / DC converter 130 in the discharge mode of the main battery 110. ) Output voltage of 13V can be controlled. Hereinafter, for convenience of description, the output voltage of the DC / DC converter 130 in the charging mode of the main battery 110 is referred to as a 'first voltage', and DC / DC in the discharge mode of the main battery 110 is described. The output voltage of the converter 130 is called 'second voltage' and used.

While the vehicle is driving in the regenerative braking mode, the driving motor of the vehicle generates a back EMF to charge the main battery 110. Therefore, the main battery 110 is operated in the charging mode while driving in the vehicular regenerative braking mode, and the converter controller 140 can control the output voltage of the DC / DC converter 130 to the first voltage. When the regenerative braking mode is terminated due to the buffering of the main battery 110, the driver's operation (such as a brake pedal or an accelerator pedal), the converter controller 140 sets the output voltage of the DC / DC converter 130 to a second voltage. Changes to

Meanwhile, when the regenerative braking termination situation occurs, the converter controller 140 immediately changes the output voltage of the DC / DC converter 130 from the first voltage to the second voltage, instead of the output voltage of the DC / DC converter 130. It may have an interval that gradually decreases from the first voltage to the second voltage. At this time, the rate of change of the output voltage of the DC / DC converter 130 (the slope of the change in the output voltage) may be differently controlled according to the charging state of the main battery 110. In this document, the rate of change of the output voltage of the DC / DC converter 130 represents a rate at which the output voltage of the DC / DC converter 130 changes with time. When the regenerative braking is terminated by the buffering of the main battery 110, the braking torque of the vehicle is the friction braking system 180 from the braking torque generated by the regenerative braking system 170 (hereinafter referred to as 'regenerative braking torque') ) Is gradually converted to the braking torque (hereinafter referred to as 'friction braking torque'). In this document, in the process of converting the braking torque of the vehicle from the regenerative braking torque to the friction braking torque, the section in which the regenerative braking torque and the friction braking torque are blended to form the braking torque of the vehicle is referred to as a 'torque blending section'. do.

The braking torque of the vehicle felt by the driver in the torque blending section in which the braking torque of the vehicle is converted from the regenerative braking torque to the friction braking torque corresponds to the sum of the regenerative braking torque and the friction braking torque. Accordingly, when the balance between the regenerative braking torque and the friction braking torque is broken during the torque blending section, a fluctuation occurs in the braking torque of the vehicle, and even with a slight braking torque fluctuation, the driver can feel a crying heterogeneity. In order to prevent such a feeling of heterogeneity, the control of the braking torque of the different species should be performed as precisely and smoothly as possible. However, the actuators of the regenerative braking system 170 generating the regenerative braking torque and the actuators of the friction braking system 180 generating the friction braking torque are different from each other and are not easy to make precisely one braking torque. In particular, the shorter the torque blending section, the more difficult it is to maintain balance between the two braking torques.

Therefore, in the vehicle control system 100 according to the embodiment of the present invention, when the regenerative braking is terminated by the buffering of the main battery 110, the change rate (change slope) of the required torque required for the regenerative braking system 170 When the regenerative braking is terminated for another reason, when the regenerative braking system 170 is controlled to be smaller than the required torque change rate, the vehicle's braking torque is converted from the regenerative braking torque to the friction braking torque by buffering the main battery 110. It can increase the length of the torque blending section. In this document, the rate of torque change refers to the rate at which the corresponding torque changes with time.

FIG. 2A shows an example of a change in braking torque when the regenerative braking is terminated by the buffering of the main battery 110, and FIG. 2B is a case where the regenerative braking is terminated for reasons other than the buffering of the main battery 110. It is shown as an example of a change in braking torque. 2A and 2B, the rate of change of the regenerative braking torque TR1 when the regenerative braking is terminated by the buffering of the main battery 110 is the rate of change of the regenerative braking torque when the regenerative braking is terminated for another reason ( It is controlled to be smaller than TR2), whereby the torque blending period when regenerative braking is terminated by the buffering of the main battery 110 may be longer than the torque blending period when regenerative braking is terminated for other reasons.

At the end of the regenerative braking, the required torque required for the regenerative braking system 170 and the friction braking system 180 may be set by the vehicle controller 160. When the required torque (or the required torque change rate) of the regenerative braking system 170 and the friction braking system 180 is determined, the vehicle controller 160 responds correspondingly to the actuators of the regenerative braking system 170 and the friction braking system 180. Control signals for controlling the may be output to the regenerative braking system 170 and the friction braking system 180, respectively.

On the other hand, increasing the torque blending section by adjusting the rate of change (tilt) of the regenerative braking torque may increase the regenerative braking time to cause overcharging of the main battery 110, which may lead to safety problems in the vehicle.

Therefore, the vehicle control system 100 according to an embodiment of the present invention, if the regenerative braking end situation is due to the buffering of the main battery 110, torque blending through the control of the rate of change of the required torque required for the regenerative braking system 170 In addition to increasing the interval, the output voltage change rate (falling slope) of the DC / DC converter 130 is gently adjusted to prevent overcharging of the main battery 110. Referring to FIG. 3, the output voltage change rate VR1 of the DC / DC converter 130 when the regenerative braking end condition is caused by the buffering of the main battery 110 is DC / DC when the regenerative braking is terminated for another reason. It may be set smaller than the output voltage change rate VR2 of the converter 130. Accordingly, when the regenerative braking is terminated by the buffering of the main battery 110, the energy used for charging the auxiliary battery 120 increases in the process of terminating the regenerative braking, thereby increasing the torque blending period. Overcharge of the battery 110 may be prevented. Therefore, when the regenerative braking is terminated by the buffering of the main battery 110, not only the smooth torque blending control is possible due to the increase in the torque blending section, but also the prevention of the overcharging of the main battery 110 due to the increase in the torque blending section can do.

Whether or not the main battery 110 is fully charged may be determined by the BMS 150. If the SOC of the main battery 110 is greater than or equal to a threshold, or the voltage of the main battery 110 is greater than or equal to a threshold, the BMS 150 may determine that the main battery 110 is in a fully charged state. On the other hand, if the SOC of the main battery 110 is less than a threshold, and the voltage of the main battery 110 is also below a threshold, the BMS 150 may determine that the main battery 110 is not in a fully charged state. Here, the threshold value used to determine whether the main battery 110 is fully charged may be an SOC value and a voltage value set in correspondence with the fully charged state of the main battery 110.

The output voltage of the DC / DC converter 130 at the end of regenerative braking may be determined by the converter controller 140. That is, at the end of the regenerative braking, the converter controller 140 receives the result of the buffer determination of the main battery 110 from the BMS 150, and based on this, the output voltage change rate of the DC / DC converter 130 in the torque blending section Can decide.

The output voltage of the DC / DC converter 130 at the end of regenerative braking may be determined by the BMS 150. That is, the BMS 150 may determine the target value of the rate of change of the output voltage of the DC / DC converter 130 in the torque blending section according to the buffering determination result of the main battery 110 at the end of regenerative braking. In this case, the BMS 150 transmits a control signal corresponding to the determined voltage change rate target value to the converter controller 140, and the converter controller 140 in the torque blending section based on the voltage change rate target value determined by the BMS 150. The output voltage of the DC / DC converter 130 can be controlled.

The output voltage of the DC / DC converter 130 at the end of regenerative braking may be determined by the vehicle controller 140. That is, the vehicle controller 140 receives the result of the determination of the buffer of the main battery 110 at the end of regenerative braking from the BMS 150, and based on this, the target value of the output voltage change rate of the DC / DC converter 130 in the torque blending section Can decide. In this case, the vehicle controller 160 transmits a control signal corresponding to the determined voltage change rate target value to the converter controller 140, and the converter controller 140 torque blending based on the voltage change rate target value determined by the vehicle controller 160. An output voltage change rate target value of the DC / DC converter 130 in the section may be set, and based on this, an output voltage of the DC / DC converter 130 in the torque blending section may be controlled.

Meanwhile, the BMS 150 and the vehicle controller 160 may respectively determine the output voltage or voltage change rate target value of the DC / DC converter 150 according to the situation, and may respectively transmit control signals corresponding thereto to the converter controller 140. have. Accordingly, the converter controller 140, which has received both control signals for the rate of voltage change from the BMS 150 and the vehicle controller 160, selects one of them and DC / DC converter 130 based on the selected control signal. ) Can control the output voltage. In this case, the BMS 150 is the rate of change of the output voltage of the DC / DC converter 130 based on whether the main battery 110 is charged, the state of charge (SOC) of the main battery 110, the voltage of the main battery 110, and the like. The target value may be determined, and a control signal for the rate of voltage change may be transmitted to the converter controller 140 correspondingly. In addition, the vehicle controller 160 determines the output voltage change rate target value of the DC / DC converter 130 based on the driving state of the vehicle, whether the high voltage electric field load is driven, and the like, and determines the voltage change rate to the converter controller 140 in response. Control signal. The converter controller 140 receiving both the output voltage or the voltage change rate target value of the DC / DC converter 130 from the BMS 150 and the vehicle controller 160 may select one of the two according to a preset selection condition. For example, when the regenerative braking is terminated by the buffering of the main battery 110, the BMS 150 sets the voltage change rate target value lower than the default value set in the torque blending section, and converts the control signal corresponding thereto. It can be output to the controller 140. In addition, the vehicle controller 160 sets the value set as the default value in the torque blending section to the voltage change rate target value regardless of whether the battery 110 is fully charged at the end of regenerative braking, and the control signal corresponding thereto to the converter controller 140 Can print In this case, the converter controller 140 prioritizes the control signal received from the BMS 150 according to a preset selection condition, and based on the control signal for the rate of voltage change received from the BMS 150, in the torque blending section. The output voltage of the DC / DC converter 130 can be controlled.

The regenerative braking system 170 is a system that controls the regenerative braking to charge the main battery 110 while decelerating the vehicle. The regenerative braking system 170 includes an actuator (not shown) for generating regenerative braking torque using a driving motor (not shown) of the vehicle, and controls it based on a control signal received from the vehicle controller 160. The output of regenerative braking torque can be controlled.

The friction braking system 180 is a system for decelerating a vehicle for frictional force. The friction braking system 180 includes an actuator (not shown) for generating a friction braking torque by controlling a brake disc pad, etc., and controlling the friction braking torque by controlling it based on a control signal received from the vehicle controller 160. The output can be controlled.

In the vehicle control system 100 described above, the BMS 150 may be packaged with at least one of the main battery 110 and the auxiliary battery 120 to configure a battery pack. Also, the BMS 150 may be packaged in the converter controller 140 and one battery pack.

Meanwhile, in FIG. 1, a case where the converter controller 140 is separately present in the vehicle BMS 150 and the vehicle controller 160 is illustrated as an example, but the present invention is not limited thereto. The function of the converter controller 140 may be implemented in the BMS 150 or the vehicle controller 160.

4 schematically illustrates a DC / DC converter control method of a vehicle control system according to an embodiment of the present invention.

Referring to FIG. 4, according to an embodiment of the present invention, the vehicle control system 100 of a vehicle receives the output voltage of the DC / DC converter 130 as a first voltage as the vehicle enters the regenerative braking mode (S100). (See V1 in FIG. 4) (S110).

In step S110, when the vehicle starts operating in the regenerative braking mode, the vehicle control system 100 gradually increases the output voltage of the DC / DC converter 130 from the second voltage (see V2 in FIG. 4) to the first voltage. Can be increased.

Then, when the regenerative braking end is requested (S120), and the main battery 110 at this time is fully charged (S130), the vehicle control system 100 of the vehicle increases the torque blending section, and DC in the torque blending section / Control the rate of change of the output voltage of the DC converter 130 to the first value (S140).

Meanwhile, in step S130, whether the main battery 110 is fully charged may be determined by comparing the SOC or voltage of the main battery 110 with a threshold value. For example, if the SOC of the main battery 110 is greater than or equal to a threshold, or if the voltage of the main battery 110 is greater than or equal to a threshold, the main battery 110 may be determined to be in a fully charged state. Further, for example, if the SOC of the main battery 110 is less than the threshold, and the voltage of the main battery 110 is less than the threshold, the main battery 110 may be determined to be not in a fully charged state.

In step S140, the vehicle control system 100 reduces the required torque change rate of the regenerative braking system 170 (see TR1 in FIG. 2A) through the vehicle controller 160, thereby reducing the torque blending period in the regenerative braking end process. Can be increased.

Meanwhile, the vehicle control system 100 of the vehicle is requested to end the regenerative braking (S120), and if the main battery 110 at this time is not fully charged (S130), the torque blending section in the regenerative braking termination process is normal. And control the output voltage change rate of the DC / DC converter 130 to a second value greater than the first value (S150).

In step S150, the normal length of the torque blending period is set to be shorter than the torque blending period in step S140. That is, in step S150, the vehicle control system 100 sets the required torque change rate of the regenerative braking system 170 through the vehicle controller 160 to an increased value (refer to TR2 in FIG. 2B) than in the step S140. , The torque blending section is controlled to be shorter than in step S140.

In step S150, the second value may be a small value that is large to the first value. That is, the output voltage of the DC / DC converter 130 may drop gently when the rate of change changes to the first value than when the rate of change changes to the second value.

In steps S140 and S150, the rate of change of the output voltage of the DC / DC converter 130 may be determined by any one of the converter controller 140, the BMS 150, and the vehicle controller 160.

For example, at the end of regenerative braking, the converter controller 140 receives the result of the buffer determination of the main battery 110 from the BMS 150, and based on this, the output voltage of the DC / DC converter 130 in the torque blending section The rate of change can be determined.

Further, for example, at the end of regenerative braking, the BMS 150 may determine the target value of the rate of change of the output voltage of the DC / DC converter 130 in the torque blending section according to the result of the buffer determination of the main battery 110.

Further, for example, at the end of regenerative braking, the vehicle controller 140 receives the result of the determination of the buffer of the main battery 110 from the BMS 150, and based on this, the DC / DC converter 130 in the torque blending section It is also possible to determine the output voltage change rate target value.

In addition, for example, at the end of regenerative braking, the BMS 150 and the vehicle controller 160 determine the output voltage or output voltage change rate target value of the DC / DC converter 150, respectively, and convert control signals corresponding thereto to the converter controller ( 140, the converter controller 140 may select one of them according to a preset selection condition. When regenerative braking is terminated by the buffering of the main battery 110, the converter controller 140 may select a control signal received from the BMS 150 according to a preset selection condition. At this time, the control signal received from the BMS 150 may correspond to the output voltage change rate (the first value) set lower than the default value in the torque blending period. On the other hand, when the regenerative braking is terminated for any reason other than the buffering of the main battery 110, the converter controller 140 may select a control signal received from the vehicle controller 160. At this time, the control signal received from the vehicle controller 160 may correspond to the output voltage change rate (second value) by default in the torque blending section.

According to the above-described exemplary embodiment of the present invention, the vehicle control system 100 torques through the control of the rate of change of the required torque required for the regenerative braking system 170 when the regenerative braking end situation is due to the buffering of the main battery 110. In addition to increasing the blending period, the output voltage change rate (falling slope) of the DC / DC converter 130 is gently adjusted. Accordingly, when the regenerative braking is terminated by the buffering of the main battery 110, not only the smooth torque blending control is possible due to the increase in the torque blending section, but also the main battery 110 is overcharged due to the increase in the torque blending section. Can be prevented.

The drawings referenced so far and the detailed description of the described invention are merely illustrative of the present invention, which are used only for the purpose of illustrating the present invention and are used to limit the scope of the present invention as defined in the claims or the claims. It is not. Therefore, those skilled in the art will understand that various modifications and other equivalent embodiments are possible. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: vehicle control system
110: main battery
120: auxiliary battery
130: DC / DC converter
140: converter controller
150: BMS
160: vehicle controller
170: regenerative braking system
180: friction braking system

Claims (9)

In the DC / DC converter control method of a battery management system mounted on a vehicle having a first battery for driving a motor, a second battery for electric load, and a DC / DC converter connected between the first and second batteries,
Controlling the output voltage of the DC / DC converter to a first voltage as the vehicle enters the regenerative braking mode,
When the termination of the regenerative braking mode is requested, changing an output voltage change rate of the DC / DC converter according to whether the first battery is fully charged, and
And reducing the output voltage of the DC / DC converter to a second voltage based on the rate of change of the output voltage. According to claim 1,
The step of changing,
And when the first battery is fully charged, setting the rate of change of the output voltage to a first value. According to claim 2,
The step of changing,
And if the first battery is not fully charged, setting the rate of change of the output voltage to a second value that is greater than the first value. According to claim 1,
And determining whether the first battery is fully charged according to a state of charge of the first battery or a voltage of the first battery. A battery pack mounted in a vehicle having a first battery for driving a motor, a second battery for electric load, and a DC / DC converter connected between the first and second batteries,
When the vehicle enters the regenerative braking mode, the output voltage of the DC / DC converter is controlled to a first voltage, and when the termination of the regenerative braking mode is requested, the DC set differently depending on whether the first battery is fully charged or not. A battery pack including a first controller that reduces the output voltage of the DC / DC converter to a second voltage based on the rate of change of the output voltage of the / DC converter. The method of claim 5,
The first controller controls the rate of change of the output voltage to a first value when the first battery is in a buffer state when requesting the termination of the regenerative braking mode, and the first battery is in a buffer state when requesting to end the regenerative braking mode. Otherwise, the battery pack for controlling the rate of change of the output voltage to a second value greater than the first value. The method of claim 5,
The battery pack further includes a battery management system that determines whether the first battery is fully charged based on a state of charge of the first battery or a voltage of the first battery. The method of claim 7,
The first controller is a battery pack that is a converter controller that controls the output voltage of the DC / DC converter. The method of claim 5,
The first controller is a battery pack that is a battery management system.

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