Vehicle power supply device

Abstract

A power supply device for a vehicle improves the power performance of the vehicle. There are: a battery pack having battery stacks (A, B) connected in parallel with each other; a switch (SWa) controlled to be in an on state connecting the battery stack (A) and an inverter (18) and in an off state separating them; a switch (SWb) controlled to be in an on state connecting the battery stack (B) and the inverter (18) and in an off state separating them; an output determination section determining which of a first output state and a second output state higher in output than the first output state the state of the battery stacks (A, B) is; and a switch control section controlling the switches (SWa, SWb), in the case where at least either of the battery stack (A) and the battery stack (B) is in the first output state, the switch control section controls one of the switches (SWa, SWb) to be in the on state and controls the other of the switches (SWa, SWb) to be in the off state.

Description

Technical Field

[0001] This invention relates to a vehicle power supply device installed in a vehicle. Background Technology

[0002] Electric vehicles, hybrid vehicles, and other vehicles are equipped with power supply devices that include energy storage components such as batteries (see Patent Documents 1-3). Furthermore, the battery assembled in the power supply device is connected to an electric motor for driving via an inverter or similar device.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2011-175963

[0004] Patent Document 2: Japanese Patent Application Publication No. 2012-226895

[0005] Patent Document 3: Japanese Patent Application Publication No. 2013-81316 Summary of the Invention

[0006] However, in low-temperature environments, the output characteristics of the battery decrease, which may reduce the vehicle's power performance. Therefore, efforts are being made to improve the vehicle's power performance.

[0007] The purpose of this invention is to improve the power performance of vehicles.

[0008] The vehicle power supply device of the present invention is a vehicle power supply device installed in a vehicle, comprising: a battery bank including a first battery and a second battery connected in parallel with the first battery; an electric motor connected to the battery bank via an inverter; a first switch controlled to an on state connecting the first battery and the inverter and an off state separating the first battery and the inverter; a second switch controlled to an on state connecting the second battery and the inverter and an off state separating the second battery and the inverter; and an output determination unit determining whether the state of the first battery is a first output state or a second output state with a higher output than the first output state. The system determines which of the output states the second battery is in and whether it is in the first or second output state; and the switch control unit controls the first switch and the second switch such that, when at least one of the first battery and the second battery is in the first output state, the switch control unit controls one of the first switch and the second switch to be in the ON state and controls the other of the first switch and the second switch to be in the OFF state; and when both the first battery and the second battery are in the second output state, the switch control unit controls both the first switch and the second switch to be in the ON state.

[0009] According to the present invention, when at least one of the first and second batteries is in a first output state, the switch control unit controls one of the first and second switches to be in an on state and controls the other of the first and second switches to be in an off state. This increases the load on the first or second battery and promotes heating of the first or second battery, thereby improving the vehicle's power performance. Attached Figure Description

[0010] Figure 1 This is a schematic diagram showing an example configuration of a vehicle equipped with a power supply device for vehicles as an embodiment of the present invention.

[0011] Figure 2 This is a schematic diagram illustrating an example of a control system for a vehicle power supply unit.

[0012] Figure 3 This is a diagram showing the execution status of the serial mode.

[0013] Figure 4 This is a diagram showing the execution status of the parallel mode.

[0014] Figure 5 This is a flowchart illustrating an example of the execution sequence of electric force calculation and control.

[0015] Figure 6 This is a flowchart illustrating an example of the execution sequence of battery temperature control.

[0016] Figure 7 This is a flowchart illustrating an example of the execution sequence of battery temperature control.

[0017] Figure 8 This is a flowchart illustrating an example of the execution sequence of battery temperature control.

[0018] Figure 9 This is a flowchart illustrating an example of the execution sequence of battery temperature control.

[0019] Figure 10 This is a flowchart illustrating an example of the execution sequence of battery temperature control.

[0020] Figure 11 This is a timing diagram illustrating an example of the execution status of battery temperature control.

[0021] (Explanation of reference numerals in the attached diagram)

[0022] 10 Vehicle power supply units

[0023] 11 vehicles

[0024] 13. Electric generator (electric motor)

[0025] 18 inverters

[0026] 20 Battery Packs (Storage Cells)

[0027] 60 Battery Controller (Switch Control Unit)

[0028] 64 main controller

[0029] 70 Output Judgment Unit

[0030] 71 Switch Target Setting Unit (Switch Control Unit)

[0031] Battery stack A (first storage element)

[0032] B. Battery stack (second battery)

[0033] C-cell battery stack

[0034] SWa switch (first switch)

[0035] SWb switch (second switch)

[0036] SWc switch

[0037] Ta~Tc temperature

[0038] SOCa~SOCc SOC Detailed Implementation

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0040] [Vehicle Composition]

[0041] Figure 1 This is a schematic diagram showing an example of the configuration of a vehicle 11 equipped with a vehicle power supply device 10 as an embodiment of the present invention. Figure 1 As shown, an electric generator (electric motor) 13 connected to wheels 12 is installed on vehicle 11. Wheels 12 are connected to the rotor 14 of electric generator 13 via a drive system 16, such as a differential mechanism 15. Furthermore, an inverter 18, serving as a power conversion device, is connected to the stator 17 of electric generator 13, and a battery pack (energy storage group) 20 is connected to the inverter 18 via power cables 19a and 19b. Moreover, a converter 22 is connected to the battery pack 20 via power cables 21a and 21b, and electrical devices 23, such as actuators and controllers, are connected to the converter 22.

[0042] The battery pack 20 has three battery stacks A to C connected in parallel. These battery stacks A to C are also referred to as battery modules. Each battery stack A to C consists of multiple battery cells 30a to 30c connected in series. Furthermore, the positive terminals 31a to 31c of each battery stack A to C are connected to the positive terminal 40 of the battery pack 20 via positive wires 41a to 41c, and the negative terminals 32a to 32c of each battery stack A to C are connected to the negative terminal 42 of the battery pack 20 via negative wires 43a to 43c.

[0043] In addition, a switch 50 consisting of three switches SWa to SWc is provided on the negative terminal side of battery stacks A to C. The first switch SWa of the switch 50 is located on the negative terminal line 43a of battery stack A (first battery cell), and the second switch SWb of the switch 50 is located on the negative terminal line 43b of battery stack B (second battery cell). The third switch SWc of the switch 50 is located on the negative terminal line 43c of battery stack C. Furthermore, battery sensors 51a to 51c are provided on each battery stack A to C, and these sensors 51a to 51c have the function of detecting the temperature, charging / discharging current, and terminal voltage of each battery stack A to C.

[0044] By controlling the switches SWA to SWc of the aforementioned switch changer 50, the connection state of battery stacks A to C within the battery pack 20 relative to the power circuit 52 can be switched. Specifically, by controlling switch SWA to the ON state, battery stack A is connected to the power circuit 52; conversely, by controlling switch SWA to the OFF state, battery stack A is disconnected from the power circuit 52. Similarly, by controlling switch SWb to the ON state, battery stack B is connected to the power circuit 52; conversely, by controlling switch SWb to the OFF state, battery stack B is disconnected from the power circuit 52. Furthermore, by controlling switch SWc to the ON state, battery stack C is connected to the power circuit 52; conversely, by controlling switch SWc to the OFF state, battery stack C is disconnected from the power circuit 52.

[0045] [Control System]

[0046] Figure 2 This is a schematic diagram illustrating an example of the control system provided with the vehicle power supply unit 10. (See diagram for example.) Figure 2As shown, the vehicle power supply unit 10 has multiple controllers 60-64, including microcomputers. These controllers 60-64 include a battery controller 60 for controlling the battery pack 20, a motor controller 61 for controlling the electric generator 13, a converter controller 62 for controlling the converter 22, an equipment controller 63 for controlling various electrical devices 23, and a main controller 64 that integrates the control of each controller 60-63. These controllers 60-64 are connected to each other via a vehicle network 65 such as CAN for free communication. Furthermore, the main controller 64 is connected to a throttle sensor 66 for detecting the operation of the accelerator pedal, a brake sensor 67 for detecting the operation of the brake pedal, and a vehicle speed sensor 68 for detecting the vehicle speed 11. Additionally, battery sensors 51a-51c are connected to the main controller 64 via the battery controller 60.

[0047] The main controller 64 is equipped with an output determination unit 70 that determines the output state of each battery stack A to C. Based on the temperature and SOC of each battery stack A to C, the output determination unit 70 of the main controller 64 determines whether each battery stack A to C is in a low output state (first output state) or a normal output state (second output state) with a higher output than the low output state. As described later, when the temperature of each battery stack A to C is low, the dischargeable power of each battery stack A to C decreases, so it is determined that each battery stack A to C is in a low output state. On the other hand, when the temperature or SOC of each battery stack A to C is high, the dischargeable power of each battery stack A to C increases, so it is determined that each battery stack A to C is in a normal output state.

[0048] Furthermore, the SOC (State of Charge) of battery stacks A through C represents the ratio of the remaining charge in battery stacks A through C to the total charge capacity. In other words, the higher the charge in battery stacks A through C, the higher the calculated SOC; conversely, the lower the charge in battery stacks A through C, the lower the calculated SOC. This SOC is calculated by the battery controller 60 based on the charging / discharging current or terminal voltage of battery stacks A through C detected by battery sensors 51a through 51c.

[0049] Furthermore, a switch target setting unit 71 is provided on the main controller 64 to set the on / off state of the switch switch 50. The switch target setting unit 71 of the main controller 64 outputs control signals corresponding to the on / off state of the switch switch 50 to the battery controller 60, thereby controlling each switch SWa to SWc of the switch switch 50 by means of the battery controller 60. In other words, the switch target setting unit 71 and the battery controller 60 function as switch control units to control each switch SWa to SWc.

[0050] Furthermore, the main controller 64 is equipped with a motor target setting unit 72 for setting the target speed and target torque of the electric generator 13. The motor target setting unit 72 of the main controller 64 outputs a control signal corresponding to the target torque to the motor controller 61, thereby controlling the inverter 18. In addition, the main controller 64 is equipped with a target power calculation unit 73 for calculating the target power supply TW required by the battery pack 20. This target power supply TW is the power consumed by the inverter 18 and converter 22 within a predetermined time.

[0051] [Battery pack operating modes]

[0052] As mentioned earlier, the battery pack 20 has three battery stacks A to C connected in parallel. The battery pack 20 can operate in two modes: a series mode where any one of the battery stacks A to C is connected to the power circuit 52, and a parallel mode where all battery stacks A to C are connected to the power circuit 52. Figure 3 This is a diagram showing the execution status of the serial mode. Figure 4 This is a diagram showing the execution status of the parallel mode.

[0053] like Figure 3 As shown, in series mode, when connecting battery stack A to power circuit 52, switch SWA is controlled to be on, switch SWb is controlled to be off, and switch SWc is controlled to be off. Therefore, only battery stack A is connected as a power source to inverter 18 and converter 22. In this series mode, when the vehicle is in motion and the electric generator 13 is controlled to be running, power is supplied from battery stack A to inverter 18. On the other hand, when the vehicle decelerates and the electric generator 13 is controlled to be in regenerative mode, power is supplied from inverter 18 to battery stack A. Additionally, power is supplied from battery stack A to converter 22 according to the operating status of electrical equipment 23.

[0054] like Figure 4 As shown, in the parallel mode where all battery stacks A to C are connected to the power supply circuit 52, all switches SWA to SWc are controlled to be in the ON state. Thus, all battery stacks A to C are connected as power sources to the inverter 18 and converter 22. In this parallel mode, when the vehicle is in motion and the electric generator 13 is controlled to operate, power is supplied from battery stacks A to C to the inverter 18. On the other hand, when the vehicle decelerates and the electric generator 13 is controlled to operate in regenerative mode, power is supplied from the inverter 18 to battery stacks A to C. Additionally, power is supplied from battery stacks A to C to the converter 22 according to the operating status of the electrical equipment 23.

[0055] As mentioned earlier, in series mode, any one of the battery stacks A through C is connected to power circuit 52; conversely, in parallel mode, all of the battery stacks A through C are connected to power circuit 52. Therefore, in Figure 3 In the series configuration shown, compared to the parallel configuration, the charging and discharging power of battery stack A can be increased, and the charging and discharging current of battery stack A can be increased. That is to say, as in... Figure 3 and Figure 4 As indicated by arrow α1, when the power consumption and regenerative power of inverter 18 and converter 22 are the same, the charging and discharging power α2 of battery stack A in series mode can be greater than that of battery stack A in parallel mode. Thus, in series mode, the load of one of the selected battery stacks A through C can be increased; on the other hand, in parallel mode, the loads of battery stacks A through C can be set to be approximately the same.

[0056] Furthermore, when the series connection mode of battery stack B to power circuit 52 is executed to increase the load on battery stack B, switch SWA is controlled to be in the open state, switch SWb is controlled to be in the closed state, and switch SWc is controlled to be in the open state. Additionally, when the series connection mode of battery stack C to power circuit 52 is executed to increase the load on battery stack C, switch SWA is controlled to be in the open state, switch SWb is controlled to be in the open state, and switch SWc is controlled to be in the closed state.

[0057] [Battery Temperature Control Flowchart]

[0058] (Electric power calculation and control)

[0059] The following section explains the electrical power calculation and control of battery stacks A to C, followed by the battery temperature control for preheating battery pack 20 in low-temperature environments. Figure 5 This is a flowchart illustrating an example of the execution sequence of electric force calculation and control. Additionally, Figures 6-10 This is a flowchart illustrating an example of the execution sequence of battery temperature rise control. Figures 6-10 In the flowchart, the parts labeled A through E are interconnected. Furthermore, it is executed in each predetermined cycle. Figure 5 The power calculation and control shown is executed in each predetermined cycle. Figures 6-10 The battery temperature control is shown. Additionally, in Figures 5-9 In this context, the battery stacks A to C are simply referred to as "Battery A to C".

[0060] like Figure 5As shown, in step S10, the temperatures Ta, Tb, and Tc of each battery stack A to C are read. In step S11, the SOCs (SOCa, SOCb, and SOCc) of each battery stack A to C are read. In the following step S12, based on the temperatures Ta and SOCa of battery stack A, the discharge capacity Wa of battery stack A is calculated by referring to predetermined chart data. Furthermore, in step S13, based on the temperatures Tb and SOCb of battery stack B, the discharge capacity Wb of battery stack B is calculated by referring to predetermined chart data. Further, in step S14, based on the temperatures Tc and SOCc of battery stack C, the discharge capacity Wc of battery stack C is calculated by referring to predetermined chart data.

[0061] Here, the dischargeable electrical forces Wa to Wc of each battery stack A to C are the electrical forces of each battery stack A to C that can be discharged within a predetermined time. Since the lower the temperature Ta to Tc of battery stacks A to C, the higher the internal resistance of battery stacks A to C, and the lower the current, the smaller the dischargeable electrical forces Wa to Wc are set. Furthermore, since the lower the SOCa to SOCc of battery stacks A to C, the lower the terminal voltage, the smaller the dischargeable electrical forces Wa to Wc are set. In other words, in the predetermined chart data referenced in the electrical force calculation and control, the lower the temperature Ta to Tc, the smaller the dischargeable electrical forces Wa to Wc are set, and the lower the SOCa to SOCc, the smaller the dischargeable electrical forces Wa to Wc are set.

[0062] (Battery temperature control)

[0063] Next, the battery temperature control will be explained. For example... Figure 6 As shown, in step S20, it is determined whether at least any one of the temperatures Ta to Tc of each battery stack A to C is below a predetermined temperature threshold Tx. If, in step S20, all temperatures Ta to Tc exceed the predetermined temperature threshold Tx, the process proceeds to step S21, where parallel operation mode is selected as the operating mode, and all switches SWa to SWc of the switchgear 50 are turned on, thus exiting the routine procedure. In other words, if the temperatures of battery stacks A to C are appropriate, and therefore it is determined that battery stacks A to C are not in a low-output state, parallel operation mode is selected as the operating mode.

[0064] (Series Mode A)

[0065] In step S20, if it is determined that at least any one of the temperatures Ta to Tc is below a predetermined temperature threshold Tx, the process proceeds to step S22, where it is determined that at least any one of the battery stacks A to C is in a low-output state. If it is determined that some or all of the battery stacks A to C are in a low-output state, the process proceeds to step S23, where the allowable temperature difference ΔT (e.g., a few degrees Celsius) between the battery stacks A to C is read, and the process proceeds to step S24, where a series mode (hereinafter referred to as series mode A) is executed with battery stack A as the operating mode. In this series mode A, switch SWA of the switchgear 50 is controlled to be in the ON state, and switches SWb and SWc are controlled to be in the OFF state. Thus, by executing series mode A, as... Figure 3 As shown, it can increase the load on battery stack A and cause the temperature Ta of battery stack A to rise earlier.

[0066] Next, as Figure 7 As shown, in step S25, it is determined whether series mode A is being executed. If it is determined in step S25 that series mode A is being executed, the process proceeds to step S26, where it is determined whether the temperature difference (Ta-Tb) between battery stacks A and B is below the allowable temperature difference ΔT. If it is determined in step S26 that the temperature difference (Ta-Tb) exceeds the allowable temperature difference ΔT, that is, if it is determined that the temperature Ta of battery stack A has risen relative to battery stack B by a predetermined temperature difference, the process proceeds to step S27, where a series mode (hereinafter referred to as series mode B) is executed with battery stack B as the target. In this series mode B, switch SWb of switchgear 50 is controlled to be in the ON state, and switches SWA and SWc are controlled to be in the OFF state. Thus, by executing series mode B, the load on battery stack B can be increased, and the temperature Tb of battery stack B can be raised earlier.

[0067] If, in step S26, it is determined that the temperature difference (Ta-Tb) is below the allowable temperature difference ΔT, then step S28 is entered to determine whether the temperature difference (Ta-Tc) between battery stacks A and C is below the allowable temperature difference ΔT. If, in step S28, it is determined that the temperature difference (Ta-Tc) exceeds the allowable temperature difference ΔT, that is, if the temperature Ta of battery stack A rises relative to battery stack C by a predetermined temperature difference, then step S29 is entered to execute a series mode (hereinafter referred to as series mode C) for battery stack C. In this series mode C, switch SWc of switchgear 50 is controlled to be in the ON state, and switches SWA and SWb are controlled to be in the OFF state. Thus, by executing series mode C, the load on battery stack C can be increased, and the temperature Tc of battery stack C can rise earlier.

[0068] If, in step S28, the temperature difference (Ta-Tc) is determined to be below the allowable temperature difference ΔT, the process proceeds to step S30, where it is determined whether the dischargeable electrical force Wa of battery stack A is below a predetermined threshold Wx. In step S30, if the dischargeable electrical force Wa exceeds the threshold Wx, the temperature Ta of battery stack A is sufficiently raised through series mode A, and battery stack A reaches its normal output state. Therefore, the process proceeds to step S31, where a temperature rise completion flag Fa indicating the completion of series mode A is set, and then to step S32, where series mode B, which raises the temperature of battery stack B, is executed.

[0069] Thus, series mode A, which raises the temperature of battery stack A, continues until the temperature Ta of battery stack A rises and the discharge capacity Wa of battery stack A exceeds the threshold Wx. Furthermore, even while series mode A is in operation, if the temperature difference (Ta-Tb) exceeds the allowable temperature difference ΔT, series mode A is interrupted and series mode B is executed; if the temperature difference (Ta-Tc) exceeds the allowable temperature difference ΔT, series mode A is interrupted and series mode C is executed. In other words, if the temperature difference between battery stacks A and C becomes excessively large, series mode A is interrupted and series mode B or series mode C is executed, heating the lower-temperature sides of battery stacks B and C.

[0070] (Series Mode B)

[0071] like Figure 7 As shown, in step S25, if it is determined that serial mode A has not been executed, then... Figure 8 As shown, proceed to step S33 to determine whether series mode B is being executed. If it is determined in step S33 that series mode B is being executed, that is, when actively raising the temperature Tb of battery stack B, proceed to step S34 to determine whether the temperature difference (Tb-Tc) between battery stacks B and C is below the allowable temperature difference ΔT. If it is determined in step S34 that the temperature difference (Tb-Tc) exceeds the allowable temperature difference ΔT, that is, when it is determined that the temperature Tb of battery stack B has risen relative to battery stack C by more than a predetermined temperature difference, proceed to step S35 to execute series mode C. In this way, by executing series mode C, the load on battery stack C can be increased, and the temperature Tc of battery stack C can be raised earlier.

[0072] If, in step S34, it is determined that the temperature difference (Tb-Tc) is below the allowable temperature difference ΔT, then proceed to step S36 to determine whether the temperature difference (Tb-Ta) between battery stacks B and A is below the allowable temperature difference ΔT. If, in step S36, it is determined that the temperature difference (Tb-Ta) exceeds the allowable temperature difference ΔT, that is, if it is determined that the temperature Tb of battery stack B has risen relative to battery stack A by exceeding a predetermined temperature difference, then proceed to step S37 to execute series mode A. Thus, by executing series mode A, the load on battery stack A can be increased, and the temperature Ta of battery stack A can rise earlier.

[0073] If, in step S36, the temperature difference (Tb-Ta) is determined to be below the allowable temperature difference ΔT, the process proceeds to step S38, where it is determined whether the dischargeable electrical force Wb of the battery stack B is below a predetermined threshold Wx. In step S38, if the dischargeable electrical force Wb exceeds the threshold Wx, it means that the temperature Tb of the battery stack B has risen sufficiently through series mode B, and the battery stack B has reached its normal output state. Therefore, the process proceeds to step S39, where a temperature rise completion flag Fb indicating the completion of series mode B is set, and then proceeds to step S40, where series mode C, which heats up the battery stack C, is executed.

[0074] Thus, series mode B, which raises the temperature of battery stack B, continues until the temperature Tb of battery stack B rises and the discharge capacity Wb of battery stack B exceeds the threshold Wx. Furthermore, even while series mode B is in operation, if the temperature difference (Tb-Tc) exceeds the allowable temperature difference ΔT, series mode B is interrupted and series mode C is executed; if the temperature difference (Tb-Ta) exceeds the allowable temperature difference ΔT, series mode B is interrupted and series mode A is executed. In other words, if the temperature difference between battery stacks A and C becomes excessively large, series mode B is interrupted, and series mode A or series mode C is executed, heating the low-temperature side of battery stacks A and C.

[0075] (Series Mode C)

[0076] like Figure 8 As shown, in step S33, if it is determined that series mode B was not executed, that is, if the temperature Tc of the battery stack C is actively increased by executing series mode C, then... Figure 9As shown, proceeding to step S41, it is determined whether the temperature difference (Tc-Ta) between battery stacks C and A is below the allowable temperature difference ΔT. If it is determined in step S41 that the temperature difference (Tc-Ta) exceeds the allowable temperature difference ΔT, that is, if it is determined that the temperature Tc of battery stack C has risen relative to battery stack A by exceeding a predetermined temperature difference, proceeding to step S42, series mode A is executed. In this way, by executing series mode A, the load on battery stack A can be increased, and the temperature Ta of battery stack A can rise earlier.

[0077] If, in step S41, it is determined that the temperature difference (Tc-Ta) is below the allowable temperature difference ΔT, then proceed to step S43 to determine whether the temperature difference (Tc-Tb) between battery stacks C and B is below the allowable temperature difference ΔT. If, in step S43, it is determined that the temperature difference (Tc-Tb) exceeds the allowable temperature difference ΔT, that is, if it is determined that the temperature Tc of battery stack C rises relative to battery stack B by exceeding a predetermined temperature difference, then proceed to step S44 to execute series mode B. Thus, by executing series mode B, the load on battery stack B can be increased, causing the temperature Tb of battery stack B to rise earlier.

[0078] If, in step S43, the temperature difference (Tc-Tb) is determined to be below the allowable temperature difference ΔT, then step S45 proceeds to determine whether the dischargeable electrical force Wc of the battery stack C is below a predetermined threshold Wx. In step S45, if the dischargeable electrical force Wc exceeds the threshold Wx, it means that the temperature Tc of the battery stack C has risen sufficiently through series mode C, and the battery stack C has reached its normal output state. Therefore, step S46 proceeds to set a temperature rise completion flag Fc indicating the completion of series mode C, and then step S47 proceeds to execute series mode A, which heats up the battery stack A.

[0079] Thus, the series mode C, which raises the temperature of battery stack C, continues until the temperature Tc of battery stack C rises and the discharge capacity Wc of battery stack C exceeds the threshold Wx. Furthermore, even while series mode C is in operation, if the temperature difference (Tc-Ta) exceeds the allowable temperature difference ΔT, series mode C is interrupted and series mode A is executed; if the temperature difference (Tc-Tb) exceeds the allowable temperature difference ΔT, series mode C is interrupted and series mode B is executed. In other words, if the temperature difference between battery stacks A and C becomes excessively large, series mode C is interrupted, and series mode A or series mode B is executed, heating the low-temperature sides of battery stacks A and B.

[0080] (Temporary power-on mode)

[0081] As mentioned earlier, when executing series mode A, series mode B, or series mode C, only one of the battery stacks A to C is connected to the power supply circuit 52. Therefore, there is a possibility of insufficient power due to the operating status of the electric generator 13 or the electrical equipment 23. Thus, in cases where there is a possibility of insufficient power, a temporary power-on mode is executed, temporarily connecting at least one of the disconnected battery stacks A to C. Next, the execution sequence of the temporary power-on modes will be explained.

[0082] like Figure 10 As shown, during the execution of series modes A to C, step S48 is entered to calculate the target power supply TW required for the battery pack 20. As mentioned earlier, the target power supply TW is the power consumed by the inverter 18 and converter 22 within a predetermined time, calculated based on the operating state of the electric generator 13 and electrical equipment 23. In the following step S49, the power that can be discharged from the battery pack 20, i.e., the dischargeable power, is calculated. This dischargeable power Wp is the power obtained by adding the dischargeable power Wa of at least one of the battery stacks A to C connected to the power supply circuit 52 of the battery pack 20. For example, when executing series mode A, the power calculated as the dischargeable power Wp is the same as the dischargeable power Wa, but when the battery stack B is temporarily connected in series mode A, the power calculated as the dischargeable power Wp is the power obtained by adding the dischargeable powers Wa and Wb.

[0083] In the next step S50, it is determined whether the dischargeable power Wp of the battery pack 20 is greater than or equal to the target supply power TW of the battery pack 20. If it is determined in step S50 that the dischargeable power Wp is lower than the target supply power TW, the dischargeable power Wp is insufficient, so the process proceeds to step S51, where, as a temporary power-on mode, any one of the selected battery stacks A to C is connected to the power supply circuit 52. This increases the dischargeable power Wp, enabling sufficient power to be supplied from the battery pack 20 to the inverter 18 and converter 22.

[0084] For example, when executing series mode A, if the dischargeable current Wp is lower than the target supply current TW, battery stack B or battery stack C is connected to power circuit 52 as a temporary power-on mode. In this temporary power-on mode, it is desirable to select the battery stack with the smaller cumulative value of charge and discharge current among battery stacks B and C, that is, to select the battery stack with less degradation to connect to power circuit 52. In this way, by connecting the battery stack with less degradation, the degradation deviation between battery stacks A to C can be suppressed. In addition, in the aforementioned temporary power-on mode, the battery stack on the low-temperature side of battery stacks B and C can be selected to connect to power circuit 52. In this case, the low-temperature battery stack can be heated, so the battery pack 20 can be preheated.

[0085] Additionally, if in step S50 it is determined that the dischargeable power Wp is greater than or equal to the target supply power TW, proceed to step S52, deactivate the temporary power-on mode, and continue with the most recent series mode A to C. In the following step S53, it is determined whether all temperature completion markers Fa to Fc have been set. If in step S53 it is determined that not all temperature completion markers Fa to Fc have been set, a battery stack in a low output state exists, so return to the previous step. Figure 7 In step S25, the series mode continues with the battery stack in the low output state as the target.

[0086] (Parallel mode)

[0087] If, in step S53, it is determined that all temperature rise completion markers Fa to Fc are set, meaning that all battery stacks A to C are in a normal output state, then step S54 is executed, switching from series mode to parallel mode. Therefore, all switches SWA to SWc are turned on, and the routine is exited. Thus, after completing the series mode A to C and achieving a normal output state for all battery stacks A to C, the parallel mode, connecting battery stacks A to C in parallel, is executed. This reduces the load on battery stacks A to C and suppresses their degradation.

[0088] [Battery Temperature Rise Control Timing Diagram]

[0089] Next, the aforementioned battery temperature control will be explained according to the timing diagram. Figure 11 This is a timing diagram illustrating an example of the execution status of battery temperature rise control. Furthermore, Figure 11 The flowchart shown illustrates the state of the vehicle 11 after starting in a low-temperature environment, where it heats each battery stack A to C while executing series mode A to C, until it switches to parallel mode.

[0090] As in Figure 11 As shown at time t1, if vehicle 11 is started in a low-temperature environment, switch SWA is controlled to be in the ON state (reference numeral Aa1), and series mode A is executed (reference numeral m1). Thus, if series mode A is executed, the temperature Ta of battery stack A rises (reference numeral Ab1), and the discharge capacity Wa of battery stack A increases (reference numeral Ac1).

[0091] At time t2, the temperature Ta of battery stack A rises relative to the temperature Tb of battery stack B, exceeding the allowable temperature difference ΔT (not shown). Therefore, switch SWA is controlled to be in the open state (reference numeral Aa2), and switch SWb is controlled to be in the closed state (reference numeral Ba1). Thus, when switching from series mode A to series mode B (reference numeral m2), the temperature Tb of battery stack B rises (reference numeral Bb1), and the discharge capacity Wb of battery stack B increases (reference numeral Bc1).

[0092] At time t3, the temperature Tb of battery stack B rises relative to the temperature Tc of battery stack C, exceeding the allowable temperature difference ΔT. Therefore, switch SWb is controlled to be in the open state (reference numeral Ba2), and switch SWc is controlled to be in the closed state (reference numeral Ca1). Thus, when switching from series mode B to series mode C (reference numeral m3), the temperature Tc of battery stack C rises (reference numeral Cb1), and the discharge capacity Wc of battery stack C increases (reference numeral Cc1).

[0093] At time t4, the temperature Tc of battery stack C rises relative to the temperature Ta of battery stack A, exceeding the allowable temperature difference ΔT. Therefore, switch SWc is controlled to be in the open state (reference numeral Ca2), and switch SWa is controlled to be in the closed state (reference numeral Aa3). Thus, when switching from series mode C to series mode A (reference numeral m4), the temperature Ta of battery stack A rises again (reference numeral Ab2), and the discharge capacity Wa of battery stack A increases again (reference numeral Ac2).

[0094] At time t5, since the dischargeable electrical capacity Wa of battery stack A reaches the threshold Wx (labeled Ac3), switch SWa is controlled to be in the open state (labeled Aa4), and switch SWb is controlled to be in the closed state (labeled Ba3). Thus, when series mode A is completed and series mode B starts again (labeled m5), the temperature Tb of battery stack B rises again (labeled Bb2), and the dischargeable electrical capacity Wb of battery stack B increases again (labeled Bc2).

[0095] At time t6, since the discharge capacity Wb of battery stack B reaches the threshold Wx (reference numeral Bc3), switch SWb is controlled to the open state (reference numeral Ba4), and switch SWc is controlled to the closed state (reference numeral Ca3). Thus, when series mode B is completed and series mode C starts again (reference numeral m6), the temperature Tc of battery stack C rises again (reference numeral Cb2), and the discharge capacity Wc of battery stack C increases again (reference numeral Cc2).

[0096] At time t7, since the dischargeable electrical power Wc of battery stack C reaches the threshold Wx (see attached figure Cc3), all switches SWa to SWc are controlled to be in the ON state (see attached figure Aa5, Ba5, Ca4). Thus, when the series mode A to C is completed, the parallel mode (see attached figure m7) begins, connecting all battery stacks A to C in parallel.

[0097] [Summarize]

[0098] The vehicle power supply device 10 of this embodiment increases the load on the battery stacks A to C by executing the series mode A to C, and promotes the heating of the battery stacks A to C. This heats the battery stacks A to C, improving output characteristics and increasing the charging and discharging efficiency of the battery stacks A to C. Therefore, by improving the charging and discharging efficiency of the battery stacks A to C, the power performance and energy efficiency of the vehicle 11 can be improved. Furthermore, the battery stacks A to C can be heated without using an electric heater, which also improves the energy efficiency of the vehicle 11.

[0099] In detail, such as using Figures 5-10 As illustrated in the flowchart, if at least one of the battery stacks A to C is determined to be in a low-output state based on its temperature Ta to Tc, then a series mode A, series mode B, or series mode C, which connects that at least one battery stack to the power supply circuit 52, is executed. This increases the load on the battery stacks A to C connected to the power supply circuit 52, allowing for preheating of the battery stacks A to C. Furthermore, since the low-output state of the battery stacks A to C is determined based on their temperature Ta to Tc, the low-output state of all battery stacks A to C can be determined without omission, allowing for the appropriate execution of series modes A to C.

[0100] Furthermore, if the temperatures Ta-Tc and SOC of all battery stacks A-C are determined to indicate that all battery stacks A-C are in a normal output state, a parallel connection mode is executed, connecting all battery stacks A-C to the power supply circuit 52. This reduces the load on battery stacks A-C, thus suppressing their degradation. Moreover, by determining whether battery stacks A-C are in a normal output state based on their temperatures Ta-Tc and SOC, the normal output state of battery stacks A-C can be reliably determined. In other words, while a low SOC in battery stacks A-C might lead to insufficient power and reduced vehicle 11's power performance, this reduction in power performance can be avoided.

[0101] The following examples illustrate the operation of battery stack A (as the first energy storage unit), battery stack B (as the second energy storage unit), switch SWA (as the first switch), and switch SWb (as the second switch).

[0102] For example, when battery stack A is in a low-output state and battery stack B is in a normal-output state, switch SWA is controlled to be in the ON state and switch SWb is controlled to be in the OFF state, executing series mode A which only charges and discharges battery stack A. This allows the load on battery stack A to be increased to raise the temperature Ta, and enables battery stack A to change from a low-output state to a normal-output state.

[0103] On the other hand, when battery stack B is in a low-output state and battery stack A is in a normal-output state, switch SWb is controlled to the ON state and switch SWA is controlled to the OFF state, executing series mode B which only charges and discharges battery stack B. This increases the load on battery stack B to raise its temperature Tb, and allows battery stack B to change from a low-output state to a normal-output state.

[0104] Additionally, if both battery stacks A and B are in a low output state, either series mode A or series mode B will be executed depending on the situation.

[0105] For example, in series mode A, if the temperature difference (Ta-Tb) between battery stacks A and B exceeds the allowable temperature difference ΔT, that is, if the temperature Ta of battery stack A rises relative to battery stack B by more than a predetermined temperature difference, the system switches from series mode A to series mode B. In other words, if both battery stacks A and B are in a low-output state, but battery stack B is colder than battery stack A, switch SWb is turned on and switch Swa is turned off, switching from series mode A to series mode B. This reduces the temperature difference (Ta-Tb) between battery stacks A and B, suppressing deviations in their output characteristics.

[0106] Similarly, when executing series mode B, if the temperature difference (Tb-Ta) between battery stacks B and A exceeds the allowable temperature difference ΔT, that is, if the temperature Tb of battery stack B rises relative to battery stack A by a predetermined temperature difference, the system switches from series mode B to series mode A. In other words, when both battery stacks A and B are in a low-output state, and battery stack A is colder than battery stack B, switch SWA is turned on and switch Swb is turned off, switching from series mode B to series mode A. This reduces the temperature difference (Tb-Ta) between battery stacks B and A, suppressing deviations in the output characteristics between them.

[0107] Thus, when at least one of battery stacks A and B is in a low output state, one of battery stacks A and B is controlled to be in the ON state, and the other is controlled to be in the OFF state, executing series mode A and B. Conversely, when both of battery stacks A and B are in the normal output state, both switches SWA and SWb are controlled to be in the ON state, executing parallel mode.

[0108] The present invention is not limited to the foregoing embodiments, and various modifications can obviously be made without departing from its spirit. In the foregoing description, the vehicle 11 that uses the vehicle power supply device 10 is exemplified as an electric vehicle that only has an electric generator 13 as a power source, but it is not limited to this, and may also be a hybrid vehicle that has an electric generator and an engine as power sources.

[0109] In the foregoing description, the determination of whether battery stacks A to C are in a low-output state is based on temperatures Ta to Tc, but it is not limited to this. For example, the dischargeable electrical forces Wa to Wc calculated based on temperature and SOC can be used to determine whether battery stacks A to C are in a low-output state. In this case, battery stacks A to C can be determined to be in a low-output state if the dischargeable electrical forces Wa to Wc are below a predetermined threshold.

[0110] In the foregoing description, the dischargeable electrical forces Wa to Wc calculated based on temperature and SOC are used to determine whether battery stacks A to C are in a normal output state, but this is not the only method. For example, if the temperatures Ta to Tc of battery stacks A to C exceed a predetermined temperature, it can be determined that battery stacks A to C are in a normal output state. Furthermore, in the foregoing description, the dischargeable electrical forces Wa to Wc that can be discharged within a predetermined time are used, but this is not the only method; the dischargeable electrical forces Wa to Wc per unit time can also be used.

[0111] In the foregoing description, the battery pack 20 is composed of three battery stacks A to C, but it is not limited to this. The battery pack can be composed of two battery stacks or four or more battery stacks. In addition, lithium-ion batteries can be used as battery units 30a to 30c, but it is not limited to this. Other types of batteries or capacitors can be used.

[0112] In the foregoing description, the switch 50 is provided on the negative terminal side of the battery stacks A to C. However, it is not limited to this; the switch 50 may also be provided on the positive terminal side of the battery stacks A to C, or on both the negative and positive terminals of the battery stacks A to C. Furthermore, the switches SWA to SWc constituting the switch 50 may be switches made of semiconductor elements such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), or switches that use electromagnetic force to mechanically open and close the contacts. Additionally, switches SWA to SWc are also referred to as relays or contactors.

Claims

1. A vehicle power supply device, installed in a vehicle, the vehicle power supply device comprising: An energy storage assembly includes a first energy storage element and a second energy storage element connected in parallel with the first energy storage element; An electric motor is connected to the energy storage group via an inverter; The first switch is controlled to be in an on state that connects the first energy storage device and the inverter to each other, and in an off state that separates the first energy storage device and the inverter from each other. The second switch is controlled to be in an on state that connects the second energy storage device and the inverter to each other, and in an off state that separates the second energy storage device and the inverter from each other. The output determination unit determines whether the state of the first energy storage cell is a first output state or a second output state with a higher output than the first output state, and determines whether the state of the second energy storage cell is the first output state or the second output state. as well as The switch control unit controls the first switch and the second switch. When at least one of the first and second batteries is in the first output state, the switch control unit controls one of the first and second switches to be in the ON state and controls the other of the first and second switches to be in the OFF state. When both the first and second batteries are in the second output state, the switch control unit controls both the first and second switches to be in the ON state. When the first energy storage device is in the first output state and the second energy storage device is in the second output state, the switch control unit controls the first switch to the on state and the second switch to the off state. When the second energy storage device is in the first output state and the first energy storage device is in the second output state, the switch control unit controls the second switch to the on state and controls the first switch to the off state.

2. The vehicle power supply device according to claim 1, wherein, When both the first and second batteries are in the first output state, and the first battery is colder than the second battery, the switch control unit controls the first switch to the ON state and the second switch to the OFF state. When both the first and second energy storage cells are in the first output state, and the second energy storage cell is at a lower temperature than the first energy storage cell, the switch control unit controls the second switch to the on state and controls the first switch to the off state.

3. The vehicle power supply device according to claim 1 or 2, wherein, The output determination unit determines whether the first energy storage device is in the first output state based on the temperature of the first energy storage device. The output determination unit determines whether the second battery is in the first output state based on the temperature of the second battery.

4. The vehicle power supply device according to claim 1 or 2, wherein, The output determination unit determines whether the first energy storage device is in the second output state based on the temperature and SOC of the first energy storage device. The output determination unit determines whether the second energy storage device is in the second output state based on the temperature and SOC of the second energy storage device.

5. The vehicle power supply device according to claim 3, wherein, The output determination unit determines whether the first energy storage device is in the second output state based on the temperature and SOC of the first energy storage device. The output determination unit determines whether the second energy storage device is in the second output state based on the temperature and SOC of the second energy storage device.

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