Battery pack, charging method thereof, and electric vehicle equipped with the same

Abstract

The present invention discloses a battery pack including first and second battery module groups, a battery pack + terminal connected to the + terminal of the second battery module group and connected to the output of an external charging system, a battery pack - terminal connected to the - terminal of the first battery module group, first and second switches respectively provided in paths between the + terminals and - terminals of the first and second battery module groups to open and close the parallel connection path of the first and second battery module groups, and a third switch provided between the first and second battery module groups to open and close the series connection path of the first and second battery module groups, a control method thereof, and an electric vehicle including the same.

Description

[Technical Field]

[0001] The present invention relates to a battery pack, and more particularly to a battery pack that can be charged to 800V using a 400V-class charger without a DC / DC converter, a charging method thereof, and an electric vehicle equipped with the same. [Background technology]

[0002] Rechargeable secondary batteries, or batteries, are widely used as energy sources for mobile devices such as smartphones. Batteries are also used as energy sources for environmentally friendly vehicles, such as electric vehicles and hybrid electric vehicles, which are proposed as a solution to address air pollution caused by fossil fuel-based gasoline and diesel vehicles. The types of applications using batteries are becoming increasingly diverse, and batteries are expected to be used in even more fields and products in the future.

[0003] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium-ion batteries. Among these, lithium-ion batteries have been gaining attention for their flexible charge and discharge cycles, as they exhibit almost no memory effect compared to nickel-based batteries, as well as their extremely low self-discharge rate and high energy density. Furthermore, because lithium-ion batteries can be manufactured to be compact and lightweight, they are being used as power sources for mobile devices and are expanding their use to include electric vehicles, drawing attention as a next-generation energy storage medium.

[0004] Such batteries are generally used in the form of a battery pack rather than as a single battery cell. A battery pack includes at least one battery module, and a battery module may consist of multiple battery cells. Battery packs are developed with high-capacity and high-voltage specifications to meet consumer needs, allowing for longer use and more powerful driving. Battery packs also include a Battery Management System (BMS) that manages the overall status of the battery cells, battery modules, or battery packs.

[0005] Meanwhile, battery packs used in electric vehicles tend to be adjusted upward from 400V to 800V. A 400V battery pack is formed by connecting multiple battery modules in series at 400V, while an 800V battery pack is formed by connecting multiple battery modules in series at 800V. That is, a 400V or 800V battery pack is formed by connecting multiple battery modules in series, each having battery cells connected in series, parallel, or series-parallel. Here, an 800V battery pack can increase voltage while reducing current, thereby improving the efficiency and performance of electric vehicles.

[0006] However, to charge an 800V battery pack, an 800V-class charger is required, but up until now, 800V-class chargers have been less common than 400V-class chargers. Therefore, there are cases where a 400V-class charger is used to charge an 800V battery pack, but a 400V-class charger cannot be used to charge an 800V battery pack. In other words, if the charging voltage of the charger is higher than the voltage of the battery pack, the battery pack can be charged, but a 400V-class charger cannot be used to charge an 800V battery pack because its charging voltage is lower than that of an 800V battery pack.

[0007] To charge an 800V battery pack using a 400V charger, a separate DC / DC converter must be installed inside the electric vehicle. That is, the 400V charger voltage must be boosted to 800V using the DC / DC converter inside the electric vehicle to charge the battery pack. However, installing a DC / DC converter inside the electric vehicle increases manufacturing costs, and if the power conversion efficiency of the DC / DC converter decreases, the battery pack may not be charged to the desired voltage.

[0008] The related prior art includes the following: [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Republic of Korea Publication Patent No. 10-2019-0069923 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a battery pack that can be charged using a charger having a charging voltage lower than the voltage of the battery pack, a charging method thereof, and an electric vehicle equipped with the same.

[0011] The present invention provides a battery pack that can be charged to 800V using a 400V-class charger without a DC / DC converter, a charging method thereof, and an electric vehicle equipped with the same.

[0012] The present invention provides a battery pack that sequentially charges a plurality of battery modules constituting the battery pack according to the charging voltage of a charger, a charging method thereof, and an electric vehicle including the same. [Means for solving the problem]

[0013] A battery pack according to one embodiment of the present invention includes first and second battery module groups, a battery pack + terminal connected to the + terminal of the second battery module group and connected to an output of an external charging system, a battery pack - terminal connected to the - terminal of the first battery module group, first and second switches respectively provided in paths between the + terminals and - terminals of the first and second battery module groups to open and close the parallel connection path of the first and second battery module groups, and a third switch provided between the first and second battery module groups to open and close the series connection path of the first and second battery module groups to open and close the series connection path of the first and second battery module groups.

[0014] The first switch is configured to open and close a path between the + terminals of the first and second battery module groups, the second switch is configured to open and close a path between the - terminals of the first and second battery module groups, and the third switch is configured to open and close a path between the + terminals of the first and second battery module groups and the - terminals of the first and second battery module groups.

[0015] When the battery pack terminals are connected to an external charging system, the first to third switches are controlled to be on / off based on a comparison result between the charging voltage of the external charging system and the voltage of the battery pack so that the first and second battery module groups are connected in series and charged collectively, or the first and second battery module groups are charged selectively or in this order.

[0016] When the charging voltage is higher than the voltage of the battery pack, the third switch is turned on, and the first and second switches are turned off, so that the first and second battery module groups are connected in series and charged collectively.

[0017] When the charging voltage is lower than the voltage of the battery pack and higher than the voltages of the first and second battery module groups, the third switch is turned off and the first and second switches are turned on in this order, controlling the first and second battery module groups to be charged in this order.

[0018] Each of the first and second battery module groups includes a plurality of battery modules, a plurality of unit series switches connected in series between the respective battery modules, and a plurality of unit parallel switches connected in parallel with the respective battery modules. When the charging voltage is lower than the voltage of the first and second battery module groups, the first and second switches are turned on in this order to selectively drive the unit series switches and unit parallel switches to selectively charge the respective battery modules of the first and second battery module groups.

[0019] A method for charging a battery pack according to another aspect of the present invention includes the steps of: comparing the voltage of the battery pack with the charging voltage of an external charging system; connecting the first and second battery module groups in series and charging them collectively when the charging voltage of the external charging system is higher than the voltage of the battery pack; charging the first and second battery module groups in this order when the charging voltage of the external charging system is lower than the voltage of the battery pack and higher than the voltages of the first and second battery module groups; and selectively charging a plurality of battery modules in each of the first and second battery module groups when the charging voltage of the external charging system is lower than the voltages of the first and second battery module groups.

[0020] When the charging voltage is higher than the voltage of the battery pack, the third switch is turned on, and the first and second switches are turned off, so that the first and second battery module groups are connected in series and charged collectively.

[0021] When the charging voltage is lower than the voltage of the battery pack and higher than the voltages of the first and second battery module groups, the first and second switches are turned on in this order to charge the first and second battery module groups in this order.

[0022] When the charging voltage is lower than the voltages of the first and second battery module groups, the first and second switches are turned on in this order, and the unit series switch and unit parallel switch are selectively controlled to be turned on / off to selectively charge the plurality of battery modules in each of the first and second battery module groups.

[0023] An electric vehicle according to yet another aspect of the present invention comprises a battery pack, a battery management system that manages the battery pack, an inverter that converts power from the battery pack into power for driving a motor, and a motor that drives the electric vehicle by receiving electrical energy from the battery pack via the inverter, wherein the battery pack comprises first and second battery module groups, first and second switches respectively provided between a charging system and the first and second battery module groups, and a third switch provided between the first and second battery module groups and connecting them.

[0024] The battery management system includes a control unit that controls the switch by comparing a charging voltage with a voltage of the battery pack when charging the battery pack.

[0025] The control unit controls the switches to charge the first and second battery module groups or selectively charge the plurality of battery modules in each of the first and second battery module groups based on a comparison result between the charging voltage of the charging system and the voltage of the battery pack.

[0026] When the charging voltage is higher than the voltage of the battery pack, the third switch is turned on, and the first and second switches are turned off, so that the first and second battery module groups are connected in series and charged collectively.

[0027] When the charging voltage is lower than the voltage of the battery pack and higher than the voltages of the first and second battery module groups, the first and second switches are turned on in this order to charge the first and second battery module groups in this order.

[0028] Each of the first and second battery module groups includes a plurality of battery modules, a plurality of unit series switches connected in series between the battery modules, and a plurality of unit parallel switches connected in parallel with the battery modules, and when the charging voltage is lower than the voltage of the first and second battery module groups, the first and second switches are turned on in this order to selectively drive the unit series switches and unit parallel switches to selectively charge the plurality of battery modules in each of the first and second battery module groups.

[0029] The battery management system turns on the third switch when discharging the battery pack, and connects the first and second battery module groups in series to discharge the battery pack. [Effects of the Invention]

[0030] A battery pack according to one embodiment of the present invention may include first and second battery module groups, each connected to a charging system via a first switch and a second switch and connected in series with each other via a third switch. Each of the first and second battery module groups may include a plurality of battery modules, with switches connected in series between the plurality of battery modules and a plurality of switches connected in parallel with the plurality of battery modules. During charging, the battery pack controls the first and second switches to charge the first and second battery module groups based on a comparison between a charging voltage of the charging system and a voltage of the battery pack, and controls a plurality of switches connected in series and in parallel with the plurality of battery modules to adjust the number of battery modules charged. During discharging, the battery pack controls the third switch to connect the first and second battery module groups in series and controls the plurality of switches to discharge the battery modules.

[0031] Therefore, according to one embodiment of the present invention, the battery pack can be charged using a charger having a charging voltage lower than the voltage of the battery pack without providing a separate DC / DC converter in the electric vehicle. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a block diagram illustrating an electric vehicle including a battery pack and a charging system according to an embodiment of the present invention. [Figure 2] 1 is a block diagram illustrating a battery pack according to an embodiment of the present invention; [Figure 3] 2 is a block diagram illustrating a battery module group constituting a battery pack according to an embodiment of the present invention. FIG. [Figure 4] 4 is a flowchart illustrating a method for controlling a battery pack according to an embodiment of the present invention. [Figure 5] 1 is a block diagram illustrating charging and discharging of a battery pack according to an embodiment of the present invention. [Figure 6] 1 is a block diagram illustrating charging and discharging of a battery pack according to an embodiment of the present invention. [Figure 7] 1 is a block diagram illustrating charging and discharging of a battery pack according to an embodiment of the present invention. [Figure 8] 1 is a block diagram illustrating charging and discharging of a battery pack according to an embodiment of the present invention. [Figure 9] 1 is a block diagram illustrating a method for charging a battery module group according to an embodiment of the present invention; [Figure 10] 1 is a block diagram illustrating a method for charging a battery module group according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The following embodiments are provided solely for the purpose of complete disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0034] Fig. 1 is a block diagram illustrating an electric vehicle and a charging system including a battery pack according to one embodiment of the present invention. That is, Fig. 1 is a block diagram illustrating the configuration of an electric vehicle and the configuration of a charging system for charging the electric vehicle. Fig. 2 is a block diagram illustrating a battery pack according to one embodiment of the present invention, and Fig. 3 is a block diagram illustrating a battery module group constituting the battery pack according to one embodiment of the present invention.

[0035] 1 to 3 , an electric vehicle 1000 to which the present invention is applied may include a battery pack 100 according to the present invention that is chargeable and dischargeable and provides electric energy for driving the electric vehicle, a battery management system (BMS) 200 that manages the battery pack 100, an inverter 300 that converts power from the battery pack 100 into power for driving a motor 400, and the motor 400 that receives electric energy from the battery pack 100 via the inverter 300 to drive the electric vehicle. In addition, a charging system 500 for charging the battery pack 100 may include first and second chargers 510 and 520 that supply charging power to the battery pack 100, and an on-board charger (OBC) 530 that converts AC power supplied from the first charger 510 into DC power and supplies it to the battery pack 100. Here, the first and second chargers 510 and 520 are installed outside the electric vehicle 1000 and connected to the electric vehicle 1000 for charging the electric vehicle 1000, and the OBC 530 is installed inside the electric vehicle 1000 and connected to the first charger 510 during charging. The electric vehicle 1000 and charging system according to one embodiment of the present invention will be described in more detail below, by component.

[0036] 1. Battery pack

[0037] The battery pack 100 is an electric energy source that can be charged and discharged and provides energy to an electric vehicle to drive the electric vehicle. Here, the battery pack 100 may include a plurality of battery modules, and the battery module may include a plurality of battery cells that can be charged and discharged. That is, a battery module may be formed by bundling a predetermined number of battery cells, or a single battery pack 100 may be formed by a plurality of battery modules. Here, the battery cells may include lithium-ion batteries. However, the battery cells may be composed of not only lithium-ion batteries but also lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc.

[0038] 2, the battery pack 100 according to the present invention may include first and second battery module groups 110 and 120. Here, the first and second battery module groups 110 and 120 may each have a voltage of, for example, 400 V. That is, the first and second battery module groups 110 and 120 may each be charged to a maximum of 400 V. The first and second battery groups 110 and 120 may be connected to the charging system 500 via first and second switches S1 and S2, respectively, or may be connected to each other via a third switch S3. Here, the first switch S1 may be provided between the positive terminal of the first battery module group 110 and the positive terminal of the second battery module group 120, and the second switch S2 may be provided between the negative terminal of the first battery module group 110 and the negative terminal of the second battery module group 120. That is, the first and second switches S1 and S2 are provided in a path between the + terminals and - terminals of the first and second battery module groups 110 and 120 to open and close the parallel connection path of the first and second battery module groups 110 and 120. In addition, the third switch S3 may be provided between the + terminals of the first and second battery module groups 110 and 120 and the - terminals of the first and second battery module groups 110 and 120. When the third switch S3 is turned on, the first and second battery module groups 110 and 120 can be connected in series. That is, the third switch S3 is provided in a path between the + terminal of the first battery module group 110 and the - terminal of the second battery module group 120 to open and close the series connection path of the first and second battery module groups 110 and 120. Therefore, when the first switch S1 is turned on, the first battery module group 110 is charged, and when the second switch S2 is turned on, the second battery module group 120 is charged.In this case, the first and second switches S1 and S2 may be controlled by the control unit 210 of the BMS 200 when charging the battery pack 100, and the first and second switches S1 and S2 may be driven in this order. That is, when the first switch S1 is turned on, the second switch S2 is turned off, and when the second switch S2 is turned on, the first switch S1 is turned off. Needless to say, depending on the charging voltage of the charging system 500, the first and second switches S1 and S2 may be turned off simultaneously. For example, when the charging voltage of the charging system 500 is 800 V, the first and second switches S1 and S2 are turned off and the third switch S3 is turned on, connecting the first and second battery module groups 110 and 120 in series, thereby simultaneously charging the first and second battery module groups 110 and 120. Alternatively, when the charging voltage of the charging system 500 is 400 V, the first and second switches S1 and S2 are turned on in this order, thereby charging the first and second battery module groups 110 and 120 in this order. In addition, the third switch S3 is controlled by the control unit 210 of the BMS 200 when the battery pack 100 is discharging. That is, the third switch S3 may be turned on when the charging system 500 is disconnected and the battery pack 100 is discharging. As described above, the battery pack 100 according to the present invention may include, for example, first and second battery module groups 110, 120 each having a voltage of 400V, which are simultaneously charged via an 800V charging system 500 and then charged via a 400V charging system 500, in that order.

[0039] As shown in FIG. 3, the first and second battery module groups 110 and 120 may each include a plurality of battery modules 111-118. While FIG. 3 illustrates the first battery module group 110, the second battery module group 120 may also include a plurality of battery modules, similar to the first battery module group 110. In this case, the first and second battery module groups 110 and 120 may be configured with the same number of battery modules. Furthermore, a plurality of switches S11-S17 may be connected in series between the plurality of battery modules 111-118, and a plurality of switches S21-S28 may be connected in parallel between the plurality of battery modules 111-118. That is, a plurality of unit series switches S11-S17 may be provided between each of the plurality of battery modules 111-118, and a plurality of unit parallel switches S21-S28 may be connected in parallel with each of the plurality of battery modules 111-118. For example, a switch S11 may be connected in series between the first and second battery modules 111, 112, or a switch S21 may be connected in parallel. Here, the multiple switches S11 to S17 connected in series between the multiple battery modules 111 to 118 control the number of battery modules 111 to 118 connected, and the multiple switches S21 to S28 connected in parallel set charging paths. That is, when a predetermined number of battery modules 111 to 118 are connected to one terminal of a charging system 500, of the multiple switches S11 to S17 connected in series, the switch between one terminal of the charging system and the last battery module is turned on, and of the multiple switches S21 to S28 connected in parallel, the switch connected from the switch connected in parallel with the last battery module to the other terminal of the charging system is turned on. For example, when the first to fourth battery modules 111 to 114 are connected, the switches S11 to S13 connected in series between them are turned on, and the switches S24 connected in parallel with the fourth battery module 114 and the subsequent switches S25 to S28 are turned on.In this way, any selected number of battery modules can be charged by using the control unit 210 to control the switches S11 to S17 connected in series with the battery modules 111 to 118 and the switches S21 to S28 connected in parallel. When discharging the battery pack 100, the battery modules 111 to 118 may be connected in series, and for this purpose, the switches S11 to S17 connected in series may be turned on and the switches S21 to S28 connected in parallel may be turned off under the control of the control unit 210.

[0040] Meanwhile, each of the battery modules 111-118 may be composed of a plurality of battery cells of the same specification. Therefore, a plurality of battery cells of the same specification may form a battery module, a plurality of battery modules may form a battery module group, and two such battery module groups may form the battery pack 100. Here, the battery cells may be connected in series and / or in parallel in various ways to meet the specifications of the electric vehicle. Needless to say, a plurality of battery packs each including a plurality of battery cells may also be connected in series and / or in parallel. For example, each of the battery modules 111-118 may have a voltage of 50V by connecting a plurality of battery cells having a voltage of 5V in series, or a plurality of battery modules 111-118 each having a voltage of 50V may be connected in series to form the battery module groups 110, 120 having a voltage of 400V.

[0041] The battery pack 100 may be configured as a single package, with the BMS 200 described below being provided within the battery pack 100.

[0042] 2. Battery Management System (BMS)

[0043] The BMS 200 estimates the state of the battery pack 100 and manages the battery pack 100 using the estimated state information. For example, the BMS 200 measures the state of the battery pack 100, such as the voltage, current, and temperature, and estimates the state of charge (SOC), state of health (SOH), and state of power (SOP) using the state information. The SOC indicates the remaining capacity of the battery, and accurate prediction of the SOC makes it possible to predict the future driving distance. The SOH indicates the battery capacity, which indicates the aging state of the battery and affects the number of times the battery can be charged and discharged. The SOP indicates the maximum power that the battery can support. Predicting the maximum power helps prevent overcharging and heat loss of the battery. The BMS 200 controls the charging or discharging of the battery pack 100 using such state information.

[0044] In addition, in order to manage the battery pack 100 using the BMS 200, the battery pack 100 may further include a sensing unit (not shown) that senses the state of the battery pack 100. The sensing unit may include a current sensor that senses the current of the battery pack 100, a voltage sensor that senses the voltage, and a temperature sensor that senses the temperature. At least one current sensor, one voltage sensor, and one temperature sensor may be provided. Here, the current sensor may sense the current of the battery pack 100, the current of the battery module groups 110 and 120, and the current of each of the plurality of battery modules 111-118. Needless to say, the current sensor may sense the current of each of the plurality of battery cells constituting the battery modules 111-118. Like the current sensor, the voltage sensor may also sense the voltages of the battery pack 100, the battery module groups 110 and 120, the plurality of battery modules 111-118, and the plurality of battery cells. In an embodiment of the present invention, the sensing unit may sense the current and voltage of the battery pack 100, the battery module groups 110 and 120, the plurality of battery modules 111 to 118, and the plurality of battery cells.

[0045] The BMS 200 also includes a charge / discharge control device. The charge / discharge control device is provided in a current path between the battery pack 100 and an external power source (i.e., a charging system) or a power consuming device (i.e., a motor) to control charging and discharging of the battery pack 100. The BMS 200 of the present invention may also include a control unit 210, as shown in FIG. 2. The control unit 210 controls switches S1, S2, and S3 of the battery pack 100 to control charging and discharging of the battery pack 100. That is, the control unit 210 controls first to third switches S1, S2, and S3 of the battery pack 100 to control charging of the first and second battery module groups 110 and 120, and controls the third switch S3 to control discharging of the first and second battery module groups 110 and 120. Furthermore, the control unit 210 can control a plurality of switches S11 to S17, S21 to S28 between the plurality of battery modules 111 to 118 that respectively constitute the battery module groups 110, 120. Therefore, according to the control of the control unit 210, the charging and discharging of the first and second battery module groups 110, 120 can be controlled, and the charging and discharging of the plurality of battery modules 111 to 118 that respectively constitute the first and second battery module groups 110, 120 can be controlled.

[0046] The control unit 210 can compare the voltage of the charging system 500 and the voltage of the battery pack 100 to control the charging of the battery pack 100. That is, the control unit 210 communicates with the charging system 500 using the communication unit 220, receives the maximum voltage range (i.e., the maximum charging voltage) that the charging system 500 can output, and compares it with the voltage of the battery pack 100. At this time, the voltage of the battery pack 100 may be stored in the memory unit 230 or may be sensed using a sensing unit (not shown). For example, if the charging voltage of the charging system 500 is 800 V and the voltage of the battery pack 100 is also 800 V, the control unit 210 can turn off the first and second switches S1 and S2 and turn on the third switch S3 to connect the first and second battery module groups 110 and 120 in series, thereby simultaneously charging the first and second battery module groups 110 and 120. Furthermore, if the charging voltage of the charging system 500 is 400V and the voltage of the battery pack 100 is 800V and it is determined that charging of the battery pack 100 is not possible, the control unit 210 controls the switches S1, S2, and S3 of the battery pack 100 to control charging of the battery pack 100. That is, the third switch S3 is turned off to separate the first and second battery module groups 110 and 120, the first switch S1 is turned on to charge the first battery module group 110, and then the second switch S2 is turned on to charge the second battery module group 120.

[0047] However, when the charging voltage of the charging system 500 is not sufficient to charge the first or second battery module group 110, 120, for example, when the charging voltage of the charging system 500 is less than 400 V and the charging voltage of the first and second battery module groups 110, 120 is 400 V, the control unit 210 may selectively charge the battery modules constituting the first or second battery module group 110, 120. For example, as shown in FIG. 3 , when the battery module group 110, 120 includes eight battery modules 111-118, at least one battery module may be selected to charge the battery module group 110, 120. To this end, the control unit 210 may control the switches S12-S17 and S21-S28 in the battery module groups 110, 120.

[0048] Meanwhile, the communication unit 220 may be provided for communication between the control unit 210 and the charging system 500. That is, when the charging system 500 is connected to the electric vehicle 1000, communication is established between a communication unit (not shown) of the charging system 500 and the communication unit 220 of the electric vehicle 1000, and the charging voltage of the charging system 500 is transferred to the control unit 210 of the electric vehicle 1000 via the communication unit 220. The memory unit 230 may also store various data for driving the electric vehicle 1000 and various data for charging, discharging, and balancing the battery pack 100. In particular, according to an embodiment of the present invention, the memory unit 230 may store the voltage of the battery pack 100. The memory unit 230 may include a Secure Digital Card (SD card), a flash memory, a USB memory, an external hard disk, or the like. Therefore, the control unit 210 can compare the charging voltage of the charging system 500 received via the communication unit 220 with the voltage of the battery pack 100 obtained from the memory unit 230, and control the charging of the battery pack 100. Needless to say, the voltage of the battery pack 100 may be determined not only from the memory unit 230 but also from a voltage value sensed by a sensing unit.

[0049] 3. Inverter

[0050] The inverter 300 drives the motor 400 so that the eco-friendly vehicle can run. That is, the inverter 30 converts the DC power of the battery pack 100 into AC power used by the motor 400, maintains an accurate charge, and controls the rotation speed and torque of the motor 400. Needless to say, eco-friendly vehicles using DC motors do not require an inverter, but to use high-performance AC motors, an inverter that can freely change frequency, voltage, rotation speed, and torque is essential.

[0051] 4. Motor

[0052] The motor 400 can provide driving force to the environmentally friendly vehicle. That is, the motor 400 can provide driving force to the wheels so that the environmentally friendly vehicle moves using energy supplied from the battery pack 100 via the inverter 300. Such a motor 400 may be, for example, at least one of an induction motor, a permanent magnet synchronous motor, and a reluctance motor. Meanwhile, the environmentally friendly vehicle may further include a motor controller for controlling the motor 400. The motor controller detects the accelerator pedal operation amount and speed, and controls the torque and rotation speed of the motor 400 according to conditions such as vehicle speed and load, so as to achieve a desired torque change. In a DC motor, the current controls the torque and the voltage controls the speed, while in an AC motor, the amplitude controls the torque and the frequency controls the speed.

[0053] 5. Charging system

[0054] The charging system 500 is provided to charge the battery pack 100 and may include first and second chargers 510, 520 that supply charging power to the battery pack 100, and an on-board charger (OBC) 530 that converts AC power supplied from the first charger 510 into DC power and supplies the DC power to the battery pack 100. Here, the first and second chargers 510, 520 are provided outside the electric vehicle 1000 and connected to the electric vehicle 1000 for charging the electric vehicle 1000, and the OBC 530 is provided inside the electric vehicle 1000 and connected to the first charger 510 during charging. Although not shown, a switch that controls connection between the chargers 510, 520 and the electric vehicle 1000 may be provided between the first and second chargers 510, 520 and the electric vehicle 1000.

[0055] The first charger 510 and the second charger 520 charge the battery pack 100 by supplying power for charging to the battery pack 100. At this time, the second charger 520 charges at a relatively higher speed than the first charger 510. For example, the charging current of the second charger 520 can provide power that is at least twice as high as the charging current of the first charger 510. This is to enable the second charger 520 to charge at a somewhat higher speed than the first charger 510. For example, the first charger 510 provides a charging voltage of 220 V, and the second charger 520 provides a charging voltage of 400 V.

[0056] The OBC 530 may be a charger installed in an electric vehicle for generating DC power using AC power received via the first charger 510. That is, the charging power from the first charger 510 is supplied to the battery pack 100 via the OBC 530, and the charging power from the second charger 520 is supplied to the battery pack 100 without passing through the OBC 530.

[0057] On the other hand, when the charging system 500 is connected to the battery pack 100, the positive terminal of the charging system 500 is connected to the positive terminal 541 of the battery pack 100, and the negative terminal of the charging system 500 is connected to the negative terminal 542 of the battery pack 100. In addition, the positive terminal of the battery pack 100 is connected to the positive terminals of the first and second battery module groups 110, 120 via the first switch S1, and the negative terminal of the battery pack 100 is connected to the negative terminals of the first and second battery module groups 110, 120 via the second switch S2.

[0058] As described above, the battery pack 100 according to one embodiment of the present invention includes first and second battery module groups 110 and 120, which are configured to include at least two battery module groups. The first and second battery module groups 110 and 120 may be connected to the charging system 500 via first and second switches S1 and S2, respectively, and connected in series with each other via a third switch S3. Each of the first and second battery module groups 110 and 120 may include a plurality of battery modules 111-118, with a plurality of unit series switches S11-S17 connected in series between the plurality of battery modules 111-118 and a plurality of unit parallel switches S21-S28 connected in parallel with the plurality of battery modules 111-118. These unit series switches S11-S17 and unit parallel switches S21-S28 are each separately controlled by the control unit 210, thereby changing the number of connections for each of the battery modules 111-118. 3 shows a configuration in which a first battery module group 110 includes a plurality of battery modules 111-118, and unit series switches S11-S17 and unit parallel switches S21-S28 are arranged. Although not shown, a second battery module group 120 may have the same structure. During charging, the battery pack 100 of the present invention controls the first and second switches S1 and S2, respectively, to charge the first and second battery module groups 110 and 120 based on a comparison result between the charging voltage of the charging system 500 and the voltage of the battery pack, and controls the number of switches S11-S17 and S21-S28, respectively, connected in series and in parallel with the plurality of battery modules 111-118 to adjust the number of battery modules 111-118 to be charged. During discharging, the third switch S3 is controlled to connect the first and second battery module groups 110, 120 in series, and the plurality of switches S11 to S17 and S21 to S28 are controlled, respectively, to allow discharging from the battery modules 111 to 118.The present invention having such a configuration can charge the battery pack using a charger having a charging voltage lower than the voltage of the battery pack without providing a separate DC / DC converter in the electric vehicle 1000.

[0059] Fig. 4 is a flowchart illustrating a method for controlling a battery pack according to an embodiment of the present invention. Figs. 5 to 8 are block diagrams illustrating charging and discharging of a battery pack according to an embodiment of the present invention, and Figs. 9 and 10 are block diagrams illustrating a method for charging a battery module group according to an embodiment of the present invention. The method for controlling a battery pack according to an embodiment of the present invention will be described below using Figs. 4 to 10.

[0060] Referring to FIG. 4, the method for controlling a battery pack according to an embodiment of the present invention includes a step of connecting a charging system to an electric vehicle (S110), a step of comparing the voltage of the battery pack with the charging voltage of the charging system (S120), a step of charging the battery pack if the voltage of the battery pack is not higher than the charging voltage (i.e., if the charging voltage is higher than the voltage of the battery pack) (S130), a step of comparing the voltage of the battery module group with the charging voltage if the voltage of the battery pack is higher than the charging voltage (S140), and a step of charging the battery pack if the voltage of the battery module group is lower than the charging voltage (i.e., if the charging voltage is higher than the voltage of the battery pack) (S140). The method may further include a step of charging the first and second battery module groups (S150) if the battery pack voltage is higher than the battery module group voltage, a step of charging at least one battery module of the battery module group to match the charging voltage (S160) if the battery pack voltage is higher than the charging voltage, and a step of discharging the battery pack by connecting the first and second battery module groups in series (S170) for driving the electric vehicle after charging of the battery pack is completed through any one of S130, S150, and S160. Each step of the method for controlling a battery pack according to an embodiment of the present invention will be described in more detail below.

[0061] First, as described with reference to FIGS. 2 and 3, a battery pack 100 according to an embodiment of the present invention may include first and second battery module groups 110 and 120. The first and second battery groups 110 and 120 may be connected to a charging system 500 via first and second switches S1 and S2, respectively, and may be connected to each other via a third switch S3. Here, the first switch S1 may be provided between the positive terminal of the first battery module group 110 and the positive terminal of the second battery module group 120, and the second switch S2 may be provided between the negative terminal of the first battery module group 110 and the negative terminal of the second battery module group 120. Furthermore, the first and second battery module groups 110 and 120 may each include a plurality of battery modules 111 to 118, as shown in FIG. 3. In this case, the first and second battery module groups 110 and 120 may be configured with the same number of battery modules. Furthermore, a plurality of switches S11 to S17 may be connected in series, and a plurality of switches S21 to S28 may be connected in parallel, between the plurality of battery modules 111 to 118. Here, the plurality of switches S11 to S17 connected in series between the plurality of battery modules 111 to 118 control the number of connections of the battery modules 111 to 118, and the plurality of switches S21 to S28 connected in parallel set charging paths.

[0062] S110: An electric vehicle 1000 equipped with a battery pack 100 consisting of first and second battery module groups 110 and 120, each of which includes a plurality of battery modules 111-118, can be connected to a charging system 500 for charging. The charging system 500 may include first and second chargers 510 and 520 that supply charging power to the battery pack 100, and an on-board charger (OBC) 530 that converts AC power supplied from the first charger 510 into DC power and supplies it to the battery pack 100. Here, the first and second chargers 510 and 520 are provided outside the electric vehicle 1000 and connected to the electric vehicle 1000 for charging the electric vehicle 1000, and the OBC 530 is provided inside the electric vehicle 1000 and connected to the first charger 510 during charging. At this time, the second charger 520 charges at a relatively higher speed than the first charger 510. For example, the charging current of the second charger 520 can provide at least twice as much power as the charging current of the first charger 510. This allows the second charger 520 to charge at a somewhat faster rate than the first charger 510. For example, the first charger 510 provides a charging voltage of 220 V, and the second charger 520 provides a charging voltage of 400 V. The OBC 530 may be a charger installed in an electric vehicle for generating DC power using AC power received via the first charger 510. That is, the charging power from the first charger 510 is supplied to the battery pack 100 via the OBC 530, and the charging power from the second charger 520 is supplied to the battery pack 100 without passing through the OBC 530.

[0063] S120: When the charging system 500 is connected to the electric vehicle 1000, information such as the charging voltage of the charging system 500 is transferred to the control unit 210 in the electric vehicle 1000 via a predetermined communication means. The control unit 210 compares the charging voltage of the charging system 500 with the voltage of the battery pack. At this time, the voltage of the battery pack may be determined using information stored in the memory unit 230 in the electric vehicle 1000, or may be determined using a value measured using a voltage sensor.

[0064] S130: If the comparison using the control unit 210 shows that the voltage of the battery pack is not higher than the charging voltage of the charging system, i.e., is lower than or equal to the charging voltage of the charging system, the battery pack 100 is charged. That is, the first and second battery module groups 110, 120 of the battery pack may be compared with the charging voltage of the charging system while connected in series via the third switch S3. If the voltage of the battery pack is lower than or equal to the charging voltage, the battery pack 100 can be charged using the charging system. For example, if the voltage of the battery pack in which the first and second battery module groups 110, 120 are connected in series via the third switch S3 is 800 V and the charging voltage of the charging system 500 is 800 V, the battery pack can be charged to a charging voltage of 800 V. To charge the first and second battery module groups 110, 120, as shown in FIG. 5, the third switch S3 is turned on and the first and second switches S1, S2 are turned off, so that the first and second battery module groups 110, 120 can be charged in a state where they are connected in series.

[0065] S140: If the comparison using the control unit 210 shows that the voltage of the battery pack is higher than the charging voltage of the charging system, the voltage of the battery module groups 110, 120 is compared with the charging voltage of the charging system 500. That is, if the voltage of the battery pack is higher than the charging voltage of the charging system, the third switch S3 is turned off to separate the first and second battery module groups 110, 120, and the voltages of the first and second battery module groups 110, 120 are compared with the charging voltage.

[0066] S150: If the comparison result shows that the voltages of the battery module groups 110 and 120 are not higher than the charging voltage, i.e., lower than or equal to the charging voltage, charge the first and second battery module groups 110 and 120, respectively. That is, as shown in FIG. 6, the first switch S1 is turned on and the second switch S2 is turned off to charge the first battery module group 110. As shown in FIG. 7, the first switch S1 is turned off and the second switch S2 is turned on to charge the second battery module group 120. For example, if the voltages of the first and second battery module groups 110 and 120 are 400 V and the charging voltage of the charging system 500 is 400 V, the first and second battery module groups 110 and 120 can be charged to a charging voltage of 400 V. The first and second switches S1 and S2 can be driven under the control of the control unit 210.

[0067] S160: If the comparison result indicates that the voltage of the battery module group is higher than the charging voltage, the battery modules 111-118 of each of the first and second battery module groups 110 and 120 are charged to match the charging voltage. For example, if the charging voltage is lower than 400V, the number of connected battery modules 111-118 may be adjusted to match the charging voltage, and the battery modules 111-118 may be charged. To this end, when a predetermined number of battery modules 111-118 are connected to one terminal of the charging system 500, among the plurality of battery modules 111-118, the plurality of unit series switches S11-S17 connected in series are turned on, from one terminal of the charging system to the switch between the last battery module, and among the plurality of unit parallel switches S21-S28 connected in parallel, the switch connected in parallel with the last battery module to the other terminal of the charging system is turned on. As an example, as shown in FIG. 9, when the first to fourth battery modules 111 to 114 are connected, the switches S11 to S13 connected in series between them are turned on, and the switches S24 to S28 connected in parallel with the fourth battery module 114 are turned on. As another example, as shown in FIG. 10, when the fifth to eighth battery modules 115 to 118 are connected, the switches S14 to S17 connected in series between them are turned on, and the switches S21 to S24 connected in parallel with the first to fourth battery modules 111 to 114 are turned on. At this time, the first switch S1 between the charging system 500 and the first battery module group 110 is turned on. In this way, by using the control unit 210 to control the multiple switches S11 to S17 connected in series with the multiple battery modules 111 to 118 and the multiple switches S21 to S28 connected in parallel, any selected number of battery modules can be charged.

[0068] S170 and S180: After the battery pack is charged via step S130, the first and second battery module groups are charged via step S150, or a predetermined number of battery module groups are charged via step S160, the first and second battery module groups may each be charged to a set maximum voltage. For example, the first and second battery module groups may each be charged to 400V. After the battery module groups and battery packs are charged in this manner, the charging system 500 is disconnected and operation of the electric vehicle may begin. To begin operation of the electric vehicle, the battery packs may be discharged. At this time, the first and second battery module groups 110 and 120 may be connected in series and then discharged. That is, as shown in FIG. 8, when the third switch S3 is turned on under the control of the control unit 210, the first and second battery module groups 110 and 120 may be connected in series. Therefore, the battery pack 100 according to the present invention may include first and second battery module groups 110 and 120 each having a voltage of, for example, 400V, and may be charged in this order via a 400V charging system 500.

[0069] Although the technical concept of the present invention as described above has been specifically described based on the above embodiment, it should be noted that the above embodiment is for the purpose of explanation and not for the purpose of limitation. It should be understood that a person skilled in the art of the present invention can implement various embodiments within the scope of the technical concept of the present invention.

Claims

1. first and second battery module groups; a battery pack positive terminal connected to the positive terminal of the second battery module group and connected to an output of an external charging system; a battery pack − terminal connected to the − terminal of the first battery module group; first and second switches respectively provided in paths between the positive terminals and negative terminals of the first and second battery module groups to open and close parallel connection paths of the first and second battery module groups; a third switch disposed between the first and second battery module groups in a path between the positive terminal of the first battery module group and the negative terminal of the second battery module group to open and close the series connection path of the first and second battery module groups; A battery pack comprising:

2. 2. The battery pack of claim 1, wherein the first switch is configured to open and close a path between positive terminals of the first and second battery module groups, the second switch is configured to open and close a path between negative terminals of the first and second battery module groups, and the third switch is configured to open and close a path between the positive terminals of the first and second battery module groups and the negative terminals of the first and second battery module groups.

3. 3. The battery pack according to claim 2, wherein, when terminals of the battery pack are connected to the external charging system, the first to third switches are controlled to be turned on / off so that the first and second battery module groups are connected in series and charged collectively, or the first and second battery module groups are charged selectively or in this order, based on a comparison result between a charging voltage of the external charging system and a voltage of the battery pack.

4. 4. The battery pack of claim 3, wherein when the charging voltage is higher than the voltage of the battery pack, the third switch is turned on and the first and second switches are turned off, so that the first and second battery module groups are connected in series and charged collectively.

5. 4. The battery pack according to claim 3, wherein when the charging voltage is lower than the voltage of the battery pack and higher than the voltages of the first and second battery module groups, the third switch is turned off and the first and second switches are turned on in this order, thereby controlling the first and second battery module groups to be charged in this order.

6. Each of the first and second battery module groups includes: a plurality of battery modules; a plurality of unit series switches connected in series between the respective battery modules; a plurality of unit parallel switches connected in parallel with the respective battery modules; Equipped with 4. The battery pack of claim 3, wherein when the charging voltage is lower than the voltages of the first and second battery module groups, the first and second switches are turned on in this order to selectively drive the plurality of unit series switches and the plurality of unit parallel switches to selectively charge the plurality of battery modules of each of the first and second battery module groups.

7. 7. The method for charging a battery pack according to claim 6, comparing the voltage of the battery pack with a charging voltage of an external charging system; When a charging voltage of the external charging system is higher than a voltage of the battery pack, the first and second battery module groups are connected in series and charged together; charging the first and second battery module groups in this order when a charging voltage of the external charging system is lower than a voltage of the battery pack and higher than voltages of the first and second battery module groups; selectively charging the plurality of battery modules of each of the first and second battery module groups when a charging voltage of the external charging system is lower than the voltages of the first and second battery module groups; How to charge the battery pack, including:

8. 8. The method for charging a battery pack according to claim 7, wherein when the charging voltage is higher than the voltage of the battery pack, the third switch is turned on and the first and second switches are turned off, so that the first and second battery module groups are connected in series and charged collectively.

9. 8. The battery pack charging method according to claim 7, wherein when the charging voltage is lower than the voltage of the battery pack and higher than the voltages of the first and second battery module groups, the first and second switches are turned on in this order to charge the first and second battery module groups in this order.

10. 8. The battery pack charging method of claim 7, wherein when the charging voltage is lower than the voltages of the first and second battery module groups, the first and second switches are turned on in this order, and the plurality of unit series switches and the plurality of unit parallel switches are selectively controlled to be turned on / off, thereby selectively charging the plurality of battery modules of each of the first and second battery module groups.

11. A battery pack and a battery management system that manages the battery pack; an inverter that converts power from the battery pack into power for driving a motor; a motor that receives electric energy from the battery pack via the inverter and drives the electric vehicle; With The battery pack first and second battery module groups; first and second switches respectively provided between a charging system and the first and second battery module groups; a third switch disposed between the first and second battery module groups to connect them; An electric vehicle equipped with

12. 12. The electric vehicle according to claim 11, wherein the battery management system includes a control unit that compares a charging voltage with a voltage of the battery pack when charging the battery pack and controls the first to third switches.

13. 13. The electric vehicle of claim 12, wherein the control unit controls the first to third switches to charge the first and second battery module groups or selectively charge the plurality of battery modules in each of the first and second battery module groups based on a comparison result between a charging voltage of the charging system and a voltage of a battery pack.

14. 14. The electric vehicle of claim 13, wherein when the charging voltage is higher than the voltage of the battery pack, the third switch is turned on and the first and second switches are turned off, so that the first and second battery module groups are connected in series and charged collectively.

15. 14. The electric vehicle according to claim 13, wherein when the charging voltage is lower than the voltage of the battery pack and higher than the voltages of the first and second battery module groups, the first and second switches are turned on in this order to charge the first and second battery module groups in this order.

16. Each of the first and second battery module groups includes: a plurality of battery modules; a plurality of unit series switches connected in series between the plurality of battery modules; a plurality of unit parallel switches connected in parallel with the plurality of battery modules; Equipped with 14. The electric vehicle of claim 13, wherein when the charging voltage is lower than the voltages of the first and second battery module groups, the first and second switches are turned on in this order to selectively drive the plurality of unit series switches and the plurality of unit parallel switches to selectively charge the plurality of battery modules in each of the first and second battery module groups.

17. 17. The electric vehicle according to claim 11, wherein the battery management system turns on the third switch when discharging the battery pack, and connects the first and second battery module groups in series to discharge the battery pack.

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