Power supply systems for mobile devices

Abstract

To provide a power supply system of a moving body capable of suppressing unintended charging / discharging from a second battery in a high-temperature state.SOLUTION: A power supply system is equipped with a voltage converter that converts voltage between a first power circuit and a second power circuit, power control means that controls the charging / discharging of first and second batteries, a cooling output control means that controls the cooling output of the second battery by a cooling device, temperature margin obtaining means that obtains a temperature margin T2_mar increased / decreased according to a difference between an upper limit temperature of the second battery and a temperature of the second battery, and cooling margin obtaining means that obtains a cooling margin PC2_mar increased / decreased according to a difference between the maximum cooling output and cooling output of a second cooling device. The power control means stops the voltage converter when at least either one of the temperature margin T2_mar or the cooling margin PC2_mar is less than a threshold value thereof, and an electric potential difference of the first and second batteries is an electric potential difference threshold value or more.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a power supply system for a mobile body, and more particularly to a power supply system for a mobile body including two power storage devices and a cooling device. [Background technology]

[0002] In recent years, there has been active development of electric vehicles, such as electric transport equipment equipped with a drive motor as a power generation source and hybrid vehicles equipped with a drive motor and an internal combustion engine as a power generation source. Such electric vehicles are also equipped with power supply devices, such as electricity storage devices (batteries, capacitors, etc.) and fuel cells, to supply electric energy to the drive motor. In recent years, electric vehicles equipped with multiple power supply devices with different characteristics have also been developed.

[0003] Patent Document 1 shows a power supply system for an electric vehicle that includes a power circuit that connects a drive unit constituted by a drive motor, an inverter, etc., to a first power storage device, a second power storage device connected to this power circuit via a voltage converter, and a control device that controls the switching of this voltage converter. The control device sets a target current for a passing current that is a current that passes through the voltage converter in response to a request from the driver, and controls the switching of the voltage converter so that the passing current becomes the target current, combines the power output from the first power storage device and the power output from the second power storage device, and supplies the result to the drive motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-169311 A Summary of the Invention [Problem to be solved by the invention]

[0005] When two storage devices are connected by a voltage converter as in this power supply system, the power output from the second storage device can basically be controlled by switching control of the voltage converter. However, when a large amount of power is required from the drive motor, for example during acceleration, the current flowing through the first storage device increases, and the closed circuit voltage of the first storage device may become lower than the static voltage of the second storage device. In this case, the second storage device may start to discharge, and an unintended current may flow through the voltage converter from the second storage device side to the first storage device side. Furthermore, if the second storage device is hot at this time, this may accelerate the deterioration of the second storage device, There is a risk of this happening.

[0006] An object of the present invention is to provide a power supply system for a mobile body that can prevent unintended charging and discharging from a second power storage device in a high temperature state. [Means for solving the problem]

[0007] (1) A power supply system (e.g., power supply system 1 described later) according to the present invention includes a first power circuit (e.g., first power circuit 2 described later) having a first power storage device (e.g., first battery B1 described later), a second power circuit (e.g., second power circuit 3 described later) having a second power storage device (e.g., second battery B2 described later) whose operating voltage range for a closed circuit voltage overlaps with that of the first power storage device and whose static voltage is lower than that of the first power storage device, a voltage converter (e.g., voltage converter 5 described later) that converts voltage between the first power circuit and the second power circuit, and a power supply circuit (e.g., power supply system 2 described later) that supplies a power to the first power storage device (e.g., first battery B1 described later). A power converter (e.g., a power converter 43 described later) that converts power between a circuit and a rotating electric machine (e.g., a drive motor M described later), power control means (e.g., a management ECU 71, a motor ECU 72, and a converter ECU 73 described later) that controls charging and discharging of the first and second power storage devices by operating the voltage converter and the power converter, and potential difference acquisition means (e.g., a management ECU 71, a first battery ECU 74, a second battery ECU 75, a first battery sensor ECU 76, a first battery sensor ECU 77, a first battery sensor ECU 78, a first battery sensor ECU 79, a second battery sensor ECU 80, a first battery sensor ECU 81, a first battery sensor ECU 82, a second battery sensor ECU 83, a first battery sensor ECU 84, a second battery sensor ECU 85, a first battery sensor ECU 86, a first battery sensor ECU 87, a second battery sensor ECU 88, a second battery sensor ECU 89, a first battery sensor ECU 90, a second battery sensor ECU 91, a first battery sensor ECU 92, a second battery sensor ECU 93, a first battery sensor ECU 94, a second battery sensor ECU 95, a first battery sensor ECU 96, a second battery sensor ECU 97, a second battery sensor ECU 98, a second battery sensor ECU 99, a first battery sensor ECU 99, a second battery sensor ECU 99, a second battery sensor ECU 99, a third battery sensor ECU 91, a fourth battery sensor ECU 92, a fourth battery sensor ECU 93, a fifth battery sensor ECU 94, a fifth battery sensor ECU 95, a sixth battery sensor ECU 96, a sixth battery sensor ECU 97, a sixth battery sensor ECU 98, a sixth battery sensor ECU 99, a seventh battery sensor ECU 99 a cooling device (e.g., a second cooling device 92 described later) that cools the second power storage device, a cooling output control means (e.g., a cooling circuit ECU 76 described later) that controls the cooling output by the cooling device, a temperature acquisition means (e.g., a second battery ECU 75 and a second battery sensor unit 82 described later) that acquires the power storage device temperature of the second power storage device, and a temperature margin (e.g., a second temperature margin T2_mar described later) that increases or decreases depending on the difference between an upper limit temperature of the second power storage device and the power storage device temperature. A power supply system comprising: a temperature margin acquisition means (e.g., a second battery ECU 75 and a second battery sensor unit 82 described below); and a cooling margin acquisition means (e.g., a cooling circuit ECU 76 described below) that acquires a cooling margin (e.g., a second cooling margin PC2_mar described below) that increases or decreases according to a difference between the maximum cooling output of the cooling device and the cooling output, wherein the power control means stops the voltage converter when at least one of the temperature margin and the cooling margin is less than a threshold value for each and the potential difference is equal to or greater than a potential difference threshold.

[0008] (2) In this case, it is preferable that after stopping the voltage converter, the power control means starts driving the voltage converter in response to both the temperature margin and the cooling margin becoming equal to or greater than the corresponding threshold value.

[0009] (3) In this case, it is preferable that the power control means disconnects the second storage device from the second power circuit when at least one of the temperature margin and the cooling margin is less than the respective threshold values ​​and the potential difference is less than the potential difference threshold value.

[0010] (4) A power supply system (e.g., power supply system 1 described later) according to the present invention includes a first power circuit (e.g., first power circuit 2 described later) having a first power storage device (e.g., first battery B1 described later), a second power circuit (e.g., second power circuit 3 described later) having a second power storage device (e.g., second battery B2 described later) whose operating voltage range for a closed circuit voltage overlaps with that of the first power storage device and whose static voltage is lower than that of the first power storage device, a voltage converter (e.g., voltage converter 5 described later) that converts voltage between the first power circuit and the second power circuit, and a power supply circuit (e.g., power supply system 1 described later) connected to the first power circuit. A power converter (e.g., a power converter 43 described later) that converts power between a rotating electric machine (e.g., a drive motor M described later) that generates a propulsive force, power control means (e.g., a management ECU 71, a motor ECU 72, and a converter ECU 73 described later) that controls charging and discharging of the first and second power storage devices by operating the voltage converter and the power converter, and potential difference acquisition means (e.g., a management ECU 71, a first battery ECU 74, a second battery ECU 75, a first battery ECU 76, a converter ECU 77, and a converter ECU 78 described later) that acquires a potential difference between the first and second power storage devices. a cooling device (e.g., a second cooling device 92 described later) that cools the second power storage device; a cooling output control means (e.g., a cooling circuit ECU 76 described later) that controls the cooling output by the cooling device; a temperature acquisition means (e.g., a second battery ECU 75 and a second battery sensor unit 82 described later) that acquires the power storage device temperature of the second power storage device; and a temperature acquisition means (e.g., a second temperature margin T2_mar described later) that acquires a temperature margin that increases or decreases depending on a difference between an upper limit temperature of the second power storage device and the power storage device temperature. The cooling circuit ECU 76 is provided with a temperature margin acquisition means (e.g., a second battery ECU 75 and a second battery sensor unit 82 described below) for acquiring a cooling margin (e.g., a second cooling margin PC2_mar described below) which increases or decreases depending on the difference between the maximum cooling output of the cooling device and the cooling output, and the power control means disconnects the second storage device from the second power circuit when at least one of the temperature margin and the cooling margin is less than a threshold value for each and the potential difference is less than a potential difference threshold value.

[0011] (5) In this case, it is preferable that after disconnecting the second storage device from the second power circuit, the power control means connects the second storage device to the second power circuit in response to both the temperature margin and the cooling margin becoming equal to or greater than the respective threshold values.

[0012] (6) In this case, it is preferable that the power control means stops the voltage converter when at least one of the temperature margin and the cooling margin is less than the respective threshold values ​​and the potential difference is equal to or greater than the potential difference threshold value.

[0013] (7) In this case, it is preferable that the power control means controls the charging and discharging of the first and second power storage devices in a normal mode or an output priority mode that allows an output from the first power circuit to the rotating electric machine that is greater than that in the normal mode, and that the cooling output control means increases the cooling output when the operation mode of the power control means is the output priority mode and the cooling margin is equal to or greater than a cooling margin threshold value, compared to when the operation mode is the normal mode. Effect of the Invention

[0014] (1) In the power supply system of the present invention, a first power circuit having a first power storage device and a second power circuit having a second power storage device whose operating voltage range for a closed circuit voltage overlaps with that of the first power storage device and whose static voltage is lower than that of the first power storage device are connected by a voltage converter, and the first power circuit and a rotating electric machine are connected by a power converter. A potential difference acquisition means acquires a potential difference between the first power storage device and the second power storage device, a temperature margin acquisition means acquires a temperature margin that increases or decreases according to a difference between an upper limit temperature of the second power storage device and a power storage device temperature of the second power storage device, and a cooling margin acquisition means acquires a cooling margin that increases or decreases according to a difference between a maximum cooling output and a cooling output of a cooling device that cools the second power storage device. In addition, the power control means stops the voltage converter when at least one of the temperature margin and the cooling margin is less than a threshold value for each and the potential difference is equal to or greater than the potential difference threshold value. Stopping the voltage converter at this time can prevent a current from flowing to at least the second power storage device, so that the temperature of the second power storage device can be lowered thereafter. Therefore, according to the present invention, it is possible to prevent unintended charging and discharging from the second storage device in a high temperature state. In particular, in the present invention, by determining the timing to stop the voltage converter taking into consideration not only the temperature margin but also the cooling margin, it is possible to stop the voltage converter at an appropriate timing taking into consideration the cooling performance of the cooling device for the second storage device. Furthermore, in the present invention, when the potential difference is equal to or greater than the potential difference threshold, the voltage converter is only stopped, so that the second storage device can be charged and discharged promptly thereafter as necessary. Note that if the voltage converter is simply stopped, the power of the second storage device may unintendedly flow through the freewheel diode of the switching element that constitutes the voltage converter, and the temperature of the second storage device may rise. In contrast, in the present invention, the voltage converter is stopped when the potential difference is equal to or greater than the potential difference threshold, so that the power of the second storage device does not unintendedly flow through the voltage converter.

[0015] (2) After stopping the voltage converter, the power control means starts driving the voltage converter in response to both the temperature margin and the cooling margin reaching or exceeding their respective thresholds. This makes it possible to more reliably prevent unintended charging and discharging from the second power storage device in a high temperature state.

[0016] (3) The power control means disconnects the second power storage device from the second power circuit when at least one of the temperature margin and the cooling margin is less than the corresponding threshold and the potential difference is less than the potential difference threshold. Here, disconnecting the second power storage device from the second power circuit can reliably prevent charging and discharging of the second power storage device, so that the temperature of the second power storage device can be reduced thereafter. Thus, according to the present invention, it is possible to prevent unintended charging and discharging from the second power storage device in a high temperature state. In particular, in the present invention, by determining the timing to disconnect the second power storage device from the second power circuit in consideration of not only the temperature margin but also the cooling margin, it is possible to disconnect the second power storage device from the second power circuit at an appropriate timing in consideration of the cooling performance of the cooling device for the second power storage device.

[0017] (4) In the present invention, when at least one of the temperature margin and the cooling margin is less than the corresponding threshold and the potential difference is less than the potential difference threshold, the power control means disconnects the second storage device from the second power circuit, reliably preventing charging and discharging of the second storage device. This makes it possible to prevent unintended charging and discharging from the second storage device in a high temperature state. In particular, in the present invention, by determining the timing to disconnect the second storage device from the second power circuit in consideration of not only the temperature margin but also the cooling margin, the second storage device can be disconnected from the second power circuit at an appropriate timing in consideration of the cooling performance of the cooling device for the second storage device. Note that if the voltage converter is simply stopped as described above, when the potential difference becomes small, the power of the second storage device may flow through the voltage converter, causing the temperature of the second storage device to rise. In contrast, in the present invention, when the potential difference is equal to or greater than the potential difference threshold, the second storage device is disconnected from the second power circuit, reliably preventing the temperature of the second storage device from rising.

[0018] (5) After disconnecting the second power storage device from the second power circuit, the power control means connects the second power storage device to the second power circuit in response to both the temperature margin and the cooling margin reaching or exceeding their respective thresholds. This makes it possible to more reliably prevent unintended charging and discharging from the second power storage device in a high temperature state.

[0019] (6) When at least one of the temperature margin and the cooling margin is less than the corresponding threshold and the potential difference is less than the potential difference threshold, the power control means stops the voltage converter to prevent current from flowing to at least the second power storage device. This makes it possible to prevent unintended charging and discharging from the second power storage device in a high temperature state. Furthermore, in the present invention, when the potential difference is equal to or greater than the potential difference threshold, the voltage converter is merely stopped, so that the second power storage device can be charged and discharged promptly thereafter as necessary.

[0020] (7) When the operation mode is the output priority mode and the cooling capacity is equal to or greater than the cooling capacity threshold, the cooling output control means increases the cooling output compared to when the operation mode is the normal mode. This makes it possible to quickly increase the temperature capacity, thereby increasing the opportunities to charge and discharge the second power storage device in the output priority mode. [Brief description of the drawings]

[0021] [Figure 1] 1 is a diagram showing the configuration of a vehicle equipped with a power supply system according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a diagram comparing the operating voltage ranges of a first battery and a second battery. [Diagram 3] FIG. 2 is a diagram illustrating an example of a circuit configuration of a voltage converter. [Figure 4] FIG. 2 is a diagram showing an example of a circuit configuration of a cooling circuit. [Diagram 5] 10 is a flowchart showing a specific procedure of a power management process. [Figure 6A] 11 is a flowchart showing a procedure for calculating a target converter passing power and a target inverter passing power in an output priority mode (part 1). [Figure 6B] 10 is a flowchart showing a procedure for calculating a target converter passing power and a target inverter passing power in the output priority mode (part 2). [Figure 6C]11 is a flowchart showing a procedure for calculating a target converter passing power and a target inverter passing power in the output priority mode (part 3). [Figure 6D] 11 is a flowchart showing a procedure for calculating a target converter passing power and a target inverter passing power in the output priority mode (part 4). [Figure 7] 5 is a diagram showing an example of an operation table for determining the output and cooling mode of a battery based on a temperature margin and a cooling margin. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a diagram showing the configuration of a four-wheeled electric vehicle V (hereinafter simply referred to as "vehicle") equipped with a power supply system 1 according to this embodiment. Note that in this embodiment, a case where the power supply system 1 is installed in a four-wheeled vehicle V will be described, but the present invention is not limited to this. The power supply system according to the present invention may be applied not only to four-wheeled vehicles V, but also to moving bodies and stationary power sources that move by propulsive force generated by a rotating electric machine, such as saddle-type vehicles, ships, robots, and unmanned aerial vehicles.

[0023] The vehicle V includes drive wheels W, a drive motor M as a rotating electric machine connected to the drive wheels W, and a power supply system 1 that exchanges electric power between the drive motor M and a first battery B1 and a second battery B2 described below. Note that in this embodiment, the vehicle V is described as accelerating and decelerating mainly by power generated by the drive motor M, but the present invention is not limited to this. The vehicle V may be a so-called hybrid vehicle equipped with the drive motor M and an engine as a power generation source.

[0024] The drive motor M is connected to the drive wheels W via a power transmission mechanism (not shown). The torque generated by the drive motor M by supplying three-phase AC power from the power supply system 1 to the drive motor M is transmitted to the drive wheels W via the power transmission mechanism (not shown), causing the drive wheels W to rotate and the vehicle V to travel. The drive motor M also functions as a generator when the vehicle V decelerates, generating regenerative power and applying a regenerative braking torque to the drive wheels W according to the magnitude of the regenerative power. The regenerative power generated by the drive motor M is appropriately charged to the batteries B1, B2 of the power supply system 1.

[0025] The power supply system 1 includes a first power circuit 2 to which a first battery B1 is connected, a second power circuit 3 to which a second battery B2 is connected, a voltage converter 5 connecting the first power circuit 2 and the second power circuit 3, a load circuit 4 having various electric loads including a drive motor M, a cooling circuit 9 to cool the first battery B1 and the second battery B2, and a group of electronic control units 7 that operate the power circuits 2, 3, 4, the cooling circuit 9, and the voltage converter 5 to control the flow of power in the power circuits 2, 3, 4, the charging and discharging of the batteries B1, B2, and the cooling output of the cooling circuit 9. The group of electronic control units 7 includes a management ECU 71, a motor ECU 72, a converter ECU 73, a first battery ECU 74, a second battery ECU 75, and a cooling circuit ECU 76, each of which is a computer.

[0026] The first battery B1 is a secondary battery capable of both discharging (converting chemical energy into electrical energy) and charging (converting electrical energy into chemical energy). In the following, a case will be described in which the first battery B1 is a so-called lithium ion storage battery that charges and discharges by moving lithium ions between electrodes, but the present invention is not limited to this.

[0027] The first battery B1 is provided with a first battery sensor unit 81 for estimating the internal state of the first battery B1. The first battery sensor unit 81 is composed of a plurality of sensors that detect physical quantities required for obtaining the charging rate (the amount of stored electricity in the battery expressed as a percentage) corresponding to the remaining amount of the first battery B1 and the temperature in the first battery ECU 74, and transmit signals according to the detected values ​​to the first battery ECU 74. More specifically, the first battery sensor unit 81 is composed of a voltage sensor that detects the terminal voltage of the first battery B1, a current sensor that detects the current flowing through the first battery B1, a temperature sensor that detects the temperature of the first battery B1, and the like.

[0028] The second battery B2 is a secondary battery capable of both discharging, which converts chemical energy into electrical energy, and charging, which converts electrical energy into chemical energy. In the following, a case will be described in which a so-called lithium ion storage battery that charges and discharges by moving lithium ions between electrodes is used as the second battery B2, but the present invention is not limited to this. The second battery B2 may be, for example, a capacitor.

[0029] The second battery B2 is provided with a second battery sensor unit 82 for estimating the internal state of the second battery B2. The second battery sensor unit 82 is composed of a plurality of sensors that detect physical quantities required for the second battery ECU 75 to acquire the charging rate, temperature, and the like of the second battery B2 and transmit signals corresponding to the detected values ​​to the second battery ECU 75. More specifically, the second battery sensor unit 82 is composed of a voltage sensor that detects the terminal voltage of the second battery B2, a current sensor that detects the current flowing through the second battery B2, a temperature sensor that detects the temperature of the second battery B2, and the like.

[0030] Here, the characteristics of the first battery B1 and the characteristics of the second battery B2 are compared. The first battery B1 has a lower output weight density and a higher energy weight density than the second battery B2. The first battery B1 also has a larger discharge capacity than the second battery B2. That is, the first battery B1 is superior to the second battery B2 in terms of energy weight density. The energy weight density is the amount of power per unit weight [Wh / kg], and the output weight density is the power per unit weight [W / kg]. Therefore, the first battery B1, which has a superior energy weight density, is a capacity-type battery mainly intended for high capacity, and the second battery B2, which has a superior output weight density, is an output-type battery mainly intended for high output. For this reason, in the power supply system 1, the first battery B1 is used as a main power supply, and the second battery B2 is used as a sub-power supply that supplements the first battery B1. The first battery B1 also has a larger heat capacity than the second battery B2. Therefore, the temperature of the first battery B1 rises more slowly than that of the second battery B2.

[0031] Fig. 2 is a diagram comparing the operating voltage ranges of the first battery B1 and the second battery B2 in the power supply system 1. In Fig. 2, the left side is a diagram showing the operating voltage range of the first battery B1, and the right side is a diagram showing the operating voltage range of the second battery B2. In Fig. 2, the horizontal axis represents the current flowing through the batteries, and the vertical axis represents the battery voltage.

[0032] As shown in FIG. 2, the static voltages of the batteries B1 and B2 (i.e., the voltage when no current flows through the battery, also called the open circuit voltage) have the characteristic that they increase as the charging rate increases. Therefore, the upper limit of the operating voltage range for the static voltages of the batteries B1 and B2 is the static voltage of each battery when the charging rate is at its maximum value (e.g., 100%), and the lower limit is the static voltage of each battery when the charging rate is at its minimum value (e.g., 0%). As shown in FIG. 2, the upper limit of the operating voltage range for the static voltage of the second battery B2 is lower than the upper limit of the operating voltage range for the static voltage of the first battery B1. Therefore, while the vehicle V is traveling, the static voltage of the second battery B2 is basically maintained lower than the static voltage of the first battery B1.

[0033] As shown in FIG. 2, the closed circuit voltages of the batteries B1 and B2 (i.e., the voltage when a current flows through the battery) also have a characteristic that the higher the charge rate, the higher the closed circuit voltage. In addition, since the batteries B1 and B2 have internal resistance, the closed circuit voltages of the batteries B1 and B2 have a characteristic that the larger the discharge current, the lower the closed circuit voltage from the static voltage, and the larger the charge current, the higher the closed circuit voltage from the static voltage. Therefore, the upper limit of the operating voltage range for the closed circuit voltage of the batteries B1 and B2 is higher than the upper limit of the operating voltage range for each static voltage, and the lower limit is lower than the lower limit of the operating voltage range for each static voltage. In other words, the operating voltage range for the closed circuit voltage of the batteries B1 and B2 includes the operating voltage range for each static voltage. As shown in FIG. 2, the operating voltage range for the closed circuit voltage of the first battery B1 overlaps with the operating voltage range for the closed circuit voltage of the second battery B2.

[0034] Moreover, since an excessively large charging current accelerates the deterioration of the batteries B1 and B2, the upper limit of the operating voltage range for the closed circuit voltage of the batteries B1 and B2 is determined based on the state of the batteries B1 and B2 so as not to deteriorate the batteries B1 and B2. Hereinafter, the upper limit of the operating range of the closed circuit voltage of the batteries B1 and B2 is also referred to as the deterioration upper limit voltage.

[0035] Moreover, if the discharge current becomes too large, the deterioration of the batteries B1, B2 will be accelerated, so the lower limit of the operating voltage range for the closed circuit voltage of the batteries B1, B2 is determined based on the state of the batteries B1, B2 so that the batteries B1, B2 do not deteriorate. Hereinafter, the lower limit of the operating voltage range for the closed circuit voltage of the batteries B1, B2 will also be referred to as the deterioration lower limit voltage.

[0036] Returning to FIG. 1, the first power circuit 2 includes a first battery B1, first power lines 21p, 21n connecting the positive and negative electrodes of the first battery B1 to the positive and negative terminals of the high-voltage side of the voltage converter 5, and a positive electrode contactor 22p and a negative electrode contactor 22n provided on the first power lines 21p, 21n.

[0037] The contactors 22p, 22n are of a normally open type that open when no command signal is input from the outside, thereby breaking the continuity between both electrodes of the first battery B1 and the first power lines 21p, 21n, and close when a command signal is input, thereby connecting the first battery B1 and the first power lines 21p, 21n. These contactors 22p, 22n open and close in response to a command signal transmitted from the first battery ECU 74. The positive electrode contactor 22p is a pre-charge contactor having a pre-charge resistor for mitigating inrush current to a plurality of smoothing capacitors provided in the first power circuit 2, the load circuit 4, etc.

[0038] The second power circuit 3 includes a second battery B2, second power lines 31p, 31n connecting the positive and negative poles of the second battery B2 to the positive and negative terminals on the low-voltage side of the voltage converter 5, a positive electrode contactor 32p and a negative electrode contactor 32n provided on the second power lines 31p, 31n, and a current sensor 33 provided on the second power line 31p.

[0039] The contactors 32p, 32n are of a normally open type that open when no command signal is input from the outside to break continuity between both electrodes of the second battery B2 and the second power lines 31p, 31n, and close when a command signal is input to connect the second battery B2 to the second power lines 31p, 31n. These contactors 32p, 32n open and close in response to a command signal transmitted from the second battery ECU 75. The positive electrode contactor 32p is a pre-charge contactor having a pre-charge resistor for mitigating inrush current to a plurality of smoothing capacitors provided in the first power circuit 2, the load circuit 4, etc.

[0040] Current sensor 33 transmits a detection signal corresponding to the current flowing through second power line 31p, i.e., the passing current which is the current flowing through voltage converter 5, to converter ECU 73. Note that in this embodiment, the direction of the passing current is positive from the second power circuit 3 side to the first power circuit 2 side, and negative from the first power circuit 2 side to the second power circuit 3 side. In other words, the passing current of voltage converter 5 is positive when second battery B2 is discharging, and is negative when second battery B2 is charging.

[0041] The load circuit 4 includes a vehicle accessory 42, a power converter 43 to which a drive motor M is connected, and load power lines 41p, 41n that connect the vehicle accessory 42 and the power converter 43 to the first power circuit 2.

[0042] The vehicle auxiliary 42 is composed of a plurality of electric loads such as a battery heater, an air compressor, a DC-DC converter, and an on-board charger. The vehicle auxiliary 42 is connected to the first power lines 21p, 21n of the first power circuit 2 by load power lines 41p, 41n, and operates by consuming power on the first power lines 21p, 21n. Information on the operating states of the various electric loads constituting the vehicle auxiliary 42 is transmitted to, for example, the management ECU 71.

[0043] The power converter 43 is connected to the first power lines 21p, 21n by the load power lines 41p, 41n so as to be in parallel with the vehicle auxiliary machine 42. The power converter 43 converts power between the first power lines 21p, 21n and the drive motor M. The power converter 43 is, for example, a PWM inverter using pulse width modulation, which includes a bridge circuit configured by connecting a plurality of switching elements (for example, IGBTs) in a bridge configuration, and has a function of converting DC power and AC power. The power converter 43 is connected to the first power lines 21p, 21n on its DC input / output side, and is connected to each of the U-phase, V-phase, and W-phase coils of the drive motor M on its AC input / output side. The power converter 43 drives the switching elements of each phase on / off in accordance with a gate drive signal generated at a predetermined timing from a gate drive circuit (not shown) of the motor ECU 72, thereby converting the DC power in the first power lines 21p, 21n into three-phase AC power and supplying it to the drive motor M, or converting the three-phase AC power supplied from the drive motor M into DC power and supplying it to the first power lines 21p, 21n.

[0044] The voltage converter 5 connects the first power circuit 2 and the second power circuit 3, and converts the voltage between these two circuits 2, 3. For this voltage converter 5, a known boost circuit is used.

[0045] 3 is a diagram showing an example of a circuit configuration of the voltage converter 5. The voltage converter 5 connects the first power lines 21p, 21n to which the first battery B1 is connected and the second power lines 31p, 31n to which the second battery B2 is connected, and converts the voltage between the first power lines 21p, 21n and the second power lines 31p, 31n. The voltage converter 5 is a full-bridge type DC-DC converter configured by combining a first reactor L1, a second reactor L2, a first high arm element 53H, a first low arm element 53L, a second high arm element 54H, a second low arm element 54L, a negative bus 55, low voltage side terminals 56p, 56n, high voltage side terminals 57p, 57n, and a smoothing capacitor (not shown).

[0046] The low voltage side terminals 56p, 56n are connected to the second power lines 31p, 31n, and the high voltage side terminals 57p, 57n are connected to the first power lines 21p, 21n. The negative bus 55 is a wiring that connects the low voltage side terminal 56n and the high voltage side terminal 57n.

[0047] One end of the first reactor L1 is connected to the low-voltage side terminal 56p, and the other end is connected to a connection node 53 between the first high arm element 53H and the first low arm element 53L. The first high arm element 53H and the first low arm element 53L each include a known power switching element such as an IGBT or a MOSFET, and a free wheel diode connected to the power switching element. The high arm element 53H and the low arm element 53L are connected in series in this order between the high-voltage side terminal 57p and the negative bus 55.

[0048] The collector of the power switching element of the first high arm element 53H is connected to the high voltage side terminal 57p, and the emitter is connected to the collector of the first low arm element 53L. The emitter of the power switching element of the first low arm element 53L is connected to the negative bus 55. The forward direction of the free wheel diode provided in the first high arm element 53H is from the first reactor L1 to the high voltage side terminal 57p. The forward direction of the free wheel diode provided in the first low arm element 53L is from the negative bus 55 to the first reactor L1.

[0049] One end of the second reactor L2 is connected to the low-voltage side terminal 56p, and the other end is connected to a connection node 54 between the second high arm element 54H and the second low arm element 54L. The second high arm element 54H and the second low arm element 54L each include a known power switching element such as an IGBT or a MOSFET, and a free wheel diode connected to the power switching element. The high arm element 54H and the low arm element 54L are connected in series between the high-voltage side terminal 57p and the negative bus 55 in this order.

[0050] The collector of the power switching element of the second high arm element 54H is connected to the high voltage side terminal 57p, and the emitter is connected to the collector of the second low arm element 54L. The emitter of the power switching element of the second low arm element 54L is connected to the negative bus 55. The forward direction of the free wheel diode provided in the second high arm element 54H is from the second reactor L2 to the high voltage side terminal 57p. The forward direction of the free wheel diode provided in the second low arm element 54L is from the negative bus 55 to the second reactor L2.

[0051] The voltage converter 5 converts the voltage between the first power lines 21p, 21n and the second power lines 31p, 31n by alternately driving on / off the first high arm element 53H and the second low arm element 54L, and the first low arm element 53L and the second high arm element 54H in accordance with a gate drive signal generated at a predetermined timing from a gate drive circuit (not shown) of the converter ECU 73.

[0052] The static voltage of the second battery B2 is basically maintained lower than the static voltage of the first battery B1. Therefore, the voltage of the first power lines 21p, 21n is basically higher than the voltage of the second power lines 31p, 31n. When the drive motor M is driven using both the power output from the first battery B1 and the power output from the second battery B2, the converter ECU 73 operates the voltage converter 5 so that a boost function is exerted in the voltage converter 5. The boost function refers to a function of boosting the power in the second power lines 31p, 31n to which the low-voltage side terminals 56p, 56n are connected, and outputting the power to the first power lines 21p, 21n to which the high-voltage side terminals 57p, 57n are connected, thereby causing a positive passing current to flow from the second power lines 31p, 31n side to the first power lines 21p, 21n side. In addition, when discharging of the second battery B2 is suppressed and the drive motor M is driven only by the power output from the first battery B1, the converter ECU 73 stops the voltage converter 5 to prevent current from flowing from the first power lines 21p, 21n to the second power lines 31p, 31n.

[0053] Furthermore, when the first battery B1 or the second battery B2 is charged by regenerative power output from the drive motor M to the first power lines 21p, 21n during deceleration, the converter ECU 73 operates the voltage converter 5 so that a step-down function is performed in the voltage converter 5. The step-down function refers to a function of stepping down the power in the first power lines 21p, 21n to which the high-voltage side terminals 57p, 57n are connected, and outputting it to the second power lines 31p, 31n to which the low-voltage side terminals 56p, 56n are connected, whereby a negative passing current flows from the first power lines 21p, 21n side to the second power lines 31p, 31n side.

[0054] Returning to FIG. 1, the first battery ECU 74 is a computer that mainly monitors the state of the first battery B1 and opens and closes the contactors 22p, 22n of the first power circuit 2. Based on a known algorithm using detection values ​​transmitted from the first battery sensor unit 81, the first battery ECU 74 calculates various parameters that represent the internal state of the first battery B1, more specifically, the temperature of the first battery B1 (hereinafter also referred to as the "first battery temperature"), the internal resistance of the first battery B1, the static voltage of the first battery B1, the closed circuit voltage of the first battery B1, a first output upper limit corresponding to the upper limit of the power that can be output from the first battery B1, a first SOC corresponding to the charging rate of the first battery B1, and a first temperature margin of the first battery B1. Information regarding the parameters that represent the internal state of the first battery B1 acquired by the first battery ECU 74 is transmitted to, for example, the management ECU 71.

[0055] Here, the first temperature margin is a parameter indicating a margin regarding the temperature of the first battery B1. More specifically, the first temperature margin is defined as a parameter that increases or decreases according to the difference between the first battery temperature and a first battery upper limit temperature, which is the upper limit of the operating temperature range of the first battery B1. The first battery ECU 74 calculates the first temperature margin by subtracting the first battery temperature from a predetermined first battery upper limit temperature. Therefore, the first temperature margin decreases as the first battery temperature increases and approaches the first battery upper limit temperature.

[0056] The second battery ECU 75 is a computer that mainly monitors the state of the second battery B2 and opens and closes the contactors 32p, 32n of the second power circuit 3. Based on a known algorithm using the detection values ​​transmitted from the second battery sensor unit 82, the second battery ECU 75 calculates various parameters that represent the internal state of the second battery B2, more specifically, the temperature of the second battery B2 (hereinafter also referred to as the "second battery temperature"), the internal resistance of the second battery B2, the static voltage of the second battery B2, the closed circuit voltage of the second battery B2, a second output upper limit corresponding to the upper limit of the power that can be output from the second battery B2, a second SOC corresponding to the charging rate of the second battery B2, and a second temperature margin of the second battery B2. Information regarding the parameters that represent the internal state of the second battery B2 acquired by the second battery ECU 75 is transmitted to, for example, the management ECU 71.

[0057] Here, the second temperature margin is a parameter indicating a margin regarding the temperature of the second battery B2. More specifically, the second temperature margin is defined as a parameter that increases or decreases according to the difference between the second battery temperature and the second battery upper limit temperature, which is the upper limit of the operating temperature range of the second battery B2. The second battery ECU 75 calculates the second temperature margin by subtracting the second battery temperature from the predetermined second battery upper limit temperature. Therefore, the second temperature margin decreases as the second battery temperature increases and approaches the second battery upper limit temperature.

[0058] Furthermore, charging and discharging a battery in a high temperature state may accelerate its deterioration. For this reason, the first output upper limit of the first battery B1 and the second output upper limit of the second battery B2 are set to be smaller as their respective temperatures increase.

[0059] The management ECU 71 is a computer that mainly manages the flow of power in the entire power supply system 1. The management ECU 71 executes a power management process, which will be described later with reference to Fig. 5, to generate an inverter passing power command signal corresponding to a command for inverter passing power, which is power passing through power converter 43, and a converter passing power command signal corresponding to a command for converter passing power, which is power passing through voltage converter 5.

[0060] The motor ECU 72 is a computer that mainly operates the power converter 43 and controls the flow of power between the first power circuit 2 and the drive motor M, i.e., the flow of inverter passing power. In the following, the inverter passing power is taken to be positive when power flows from the first power circuit 2 to the drive motor M, i.e., when the drive motor M is in power running operation. The inverter passing power is taken to be negative when power flows from the drive motor M to the first power circuit 2, i.e., when the drive motor M is in regenerative operation. The motor ECU 72 operates the power converter 43 in response to an inverter passing power command signal transmitted from the management ECU 71 so that the inverter passing power corresponding to the command passes through the power converter 43, in other words, so that a torque corresponding to the inverter passing power is generated in the drive motor M.

[0061] The converter ECU 73 is a computer that mainly operates the voltage converter 5 and controls the flow of power between the first power circuit 2 and the second power circuit 3, i.e., the flow of converter passing power. In the following, the converter passing power is positive when power flows from the second power circuit 3 to the first power circuit 2, i.e., when power is discharged from the second battery B2 and supplied to the first power circuit 2. The converter passing power is negative when power flows from the first power circuit 2 to the second power circuit 3, i.e., when the second battery B2 is charged with the power in the first power circuit 2. In response to a converter passing power command signal transmitted from the management ECU 71, the converter ECU 73 operates the voltage converter 5 so that the converter passing power according to the command passes through the voltage converter 5. More specifically, the converter ECU 73 calculates a target current, which is a target for the passing current in the voltage converter 5, based on the converter passing power command signal, and operates the voltage converter 5 according to a known feedback control algorithm so that the passing current detected by the current sensor 33 (hereinafter also referred to as the "actual passing current") becomes the target current.

[0062] As described above, in the power supply system 1, the management ECU 71, the motor ECU 72, and the converter ECU 73 operate the voltage converter 5 and the power converter 43, and the charging and discharging of the first battery B1 and the second battery B2 can be controlled by controlling the passing power of the voltage converter 5 and the power converter 43. Therefore, in this embodiment, a power control means for controlling the charging and discharging of the first battery B1 and the second battery B2 is composed of the management ECU 71, the motor ECU 72, and the converter ECU 73. More specifically, the power control means controls the converter passing power to P2 and the inverter passing power to P1+P2, thereby controlling the input / output power of the first battery B1 and the input / output power of the second battery B2 to P1 and P2, respectively.

[0063] FIG. 4 is a diagram showing the circuit configuration of the cooling circuit 9. The cooling circuit 9 includes a first cooling device 91 that cools the first battery B1, a second cooling device 92 that cools the second battery B2, and a third cooling device 93 that cools the voltage converter 5 and the power converter 43.

[0064] The first cooling device 91 includes a first cooling water circulation path 911 including a cooling water flow path formed in a battery case that houses the first battery B1, a first heat exchanger 912 and a first cooling water pump 913 provided in the first cooling water circulation path 911, and a heating device 94 connected to the first cooling water circulation path 911.

[0065] The first coolant pump 913 rotates in response to a command input from the cooling circuit ECU 76, and circulates the coolant in the first coolant circulation path 911. The first heat exchanger 912 promotes heat exchange between the coolant circulating in the first coolant circulation path 911 and the outside air, thereby cooling the coolant whose temperature has been increased by heat exchange with the first battery B1. The first heat exchanger 912 includes a radiator fan that rotates in response to a command input from the cooling circuit ECU 76.

[0066] The heating device 94 includes a bypass path 941 that connects the inlet and outlet of the first heat exchanger 912 in the first cooling water circulation path 911 and bypasses the first heat exchanger 912, a heater 942 and a heating pump 943 provided in the bypass path 941, and three-way valves 944, 945 provided at the connection between both ends of the bypass path 941 and the first cooling water circulation path 911.

[0067] The heating pump 943 rotates in response to a command input from the cooling circuit ECU 76, and circulates the cooling water in the first cooling water circulation path 911 and the bypass path 941. The heater 942 generates heat by consuming power supplied from a battery (not shown), and increases the temperature of the cooling water flowing through the bypass path 941.

[0068] The three-way valves 944, 945 open and close in response to commands from the cooling circuit ECU 76, switching the flow path of the coolant between the first heat exchanger 912 side and the heater 942 side. Therefore, the first cooling device 91 has two functions: a cooling function of cooling the first battery B1 by circulating the coolant cooled by the first heat exchanger 912, and a heating function of heating the first battery B1 by circulating the coolant heated by the heater 942.

[0069] The cooling circuit ECU 76 controls the first cooling output of the first battery B1 by the first cooling device 91 by operating the first heat exchanger 912, the first cooling water pump 913, the heater 942, the heating pump 943, and the three-way valves 944, 945 based on the first battery temperature transmitted from the first battery ECU 74, the detection value of a first cooling water temperature sensor (not shown) that detects the temperature of the cooling water flowing through the first cooling water circulation path 911, the detection value of an outside air temperature sensor (not shown), and commands from the management ECU 71, etc. Here, the first cooling output is a parameter that increases or decreases according to the cooling performance of the first battery B1 by the first cooling device 91, and is, for example, the rotation speed of a radiator fan provided in the first heat exchanger 912.

[0070] The cooling circuit ECU 76 also calculates a first cooling margin corresponding to the margin of cooling of the first battery B1 by the first cooling device 91, and transmits this first cooling margin to the management ECU 71. More specifically, the cooling circuit ECU 76 calculates the first cooling margin by subtracting the current first cooling output from a first maximum cooling output (e.g., the maximum rotation speed of the radiator fan) corresponding to the maximum value of the first cooling output of the first cooling device 91. That is, this first cooling margin increases or decreases according to the difference between the first maximum cooling output and the first cooling output. Note that a specific procedure for controlling the first cooling output in the cooling circuit ECU 76 will be described later.

[0071] The second cooling device 92 includes, for example, a cooling fan that supplies outside air into a battery case that accommodates the second battery B2. The second cooling device 92 rotates in response to a command from the cooling circuit ECU 76, and cools the second battery B2 by supplying outside air into the battery case of the second battery B2.

[0072] The cooling circuit ECU 76 controls the second cooling output of the second battery B2 by the second cooling device 92 by operating the second cooling device 92 based on the second battery temperature transmitted from the second battery ECU 75, the detection value of the outside air temperature sensor, and commands from the management ECU 71. Here, the second cooling output is a parameter that increases or decreases according to the cooling performance of the second battery B2 by the second cooling device 92, and is, for example, the rotation speed of the cooling fan of the second cooling device 92.

[0073] The cooling circuit ECU 76 also calculates a second cooling margin corresponding to the margin of cooling of the second battery B2 by the second cooling device 92, and transmits this second cooling margin to the management ECU 71. More specifically, the cooling circuit ECU 76 calculates the second cooling margin by subtracting the current second cooling output from a second maximum cooling output (e.g., the maximum rotation speed of the cooling fan) corresponding to the maximum value of the second cooling output of the second cooling device 92. That is, this second cooling margin increases or decreases according to the difference between the second maximum cooling output and the second cooling output. Note that a specific procedure for controlling the second cooling output in the cooling circuit ECU 76 will be described later.

[0074] The third cooling device 93 includes a third cooling water circulation path 931 including a cooling water flow path formed in a housing in which the voltage converter 5 and the power converter 43 are installed, and a third heat exchanger 932 and a third cooling water pump 933 provided in this third cooling water circulation path 931.

[0075] The third coolant pump 933 rotates in response to a command input from the cooling circuit ECU 76, and circulates the coolant in the third coolant circulation path 931. The third heat exchanger 932 promotes heat exchange between the coolant circulating in the third coolant circulation path 931 and the outside air, thereby cooling the coolant whose temperature has been raised by heat exchange with the voltage converter 5 and the power converter 43. The third heat exchanger 932 is equipped with a radiator fan that rotates in response to a command input from the cooling circuit ECU 76.

[0076] The cooling circuit ECU 76 controls the third cooling output, which corresponds to the cooling performance of the voltage converter 5 and the power converter 43 by the third cooling device 93, by operating the third heat exchanger 932 and the third cooling water pump 933 based on the detection value of a cooling water temperature sensor (not shown) and commands from the management ECU 71.

[0077] As described above, in this embodiment, the first cooling device 91 for cooling the first battery B1 and the third cooling device 93 for cooling the voltage converter 5 and the like are water-cooled by heat exchange with cooling water, and the second cooling device 92 for cooling the second battery B2, which has a smaller heat capacity than the first battery B1, is air-cooled by heat exchange with outside air, but the present invention is not limited to this. The first cooling device 91 may be air-cooled, the second cooling device 92 may be water-cooled, or the third cooling device 93 may be air-cooled. In this embodiment, the circulation flow path of the cooling water for cooling the first battery B1 and the circulation flow path of the cooling water for cooling the voltage converter 5 and the power converter 43 are separate systems, but the present invention is not limited to this. Both or either of the voltage converter 5 and the power converter 43 may be cooled by the cooling water for cooling the first battery B1.

[0078] 5 is a flowchart showing a specific procedure of the power management process. This power management process is repeatedly executed in the management ECU 71 at a predetermined cycle from when the driver turns on a start switch (not shown) to start the vehicle V and the power supply system 1 until the driver turns off the start switch again to stop the vehicle V and the power supply system 1.

[0079] First, in step S1, the management ECU 71 calculates the driving torque required by the driver based on the amount of operation of the accelerator pedal, brake pedal, etc. (see Figure 1) by the driver, and converts this required driving torque into power to calculate the request for inverter passing power in the power converter 43, i.e., the required inverter passing power Pmot_d, which corresponds to the required output of the drive motor M, and then proceeds to step S2.

[0080] Next, in step S2, the management ECU 71 determines whether the required inverter passing power Pmot_d calculated in step S1 is equal to or greater than the high output threshold Phigh. If the determination result in step S2 is NO, the management ECU 71 proceeds to step S3, and if the determination result is YES, the management ECU 71 proceeds to step S4.

[0081] Next, in step S3, the management ECU 71 calculates a target converter passing power Pcnv_cmd corresponding to a target for the converter passing power and a target inverter passing power Pmot_cmd corresponding to a target for the inverter passing power under normal mode, and proceeds to step S7. Here, under normal mode, the management ECU 71 calculates the target converter passing power Pcnv_cmd and the target inverter passing power Pmot_cmd so that power is input / output from the first battery B1 and the second battery B2 under a target ratio calculated based on a predetermined algorithm. Also, under normal mode, the management ECU 71 limits the target inverter passing power Pmot_cmd to be equal to or lower than the above-mentioned high output threshold Phigh.

[0082] Next, in step S7, the management ECU 71 generates a converter passing power command signal corresponding to the target converter passing power Pcnv_cmd, transmits this to the converter ECU 73, and proceeds to step S8. As a result, power corresponding to the target converter passing power Pcnv_cmd is charged to or discharged from the second battery B2.

[0083] Next, in step S8, the management ECU 71 generates an inverter passing power command signal corresponding to the target inverter passing power Pmot_cmd, transmits this to the motor ECU 72, and ends the processing in Fig. 5. As a result, power corresponding to the target inverter passing power Pmot_cmd flows between the first power circuit 2 and the drive motor M. Also, as a result, power obtained by subtracting the target converter passing power Pcnv_cmd from the target inverter passing power Pmot_cmd is charged to and discharged from the first battery B1.

[0084] Next, in step S4, the management ECU 71 determines whether or not a fuel efficiency priority button (not shown) has been pressed by the driver, in other words, whether or not the driver has issued an instruction to permit execution of an output priority mode (described later). If the determination result in step S4 is YES, the management ECU 71 proceeds to step S5, where it executes limiting processing to limit the required inverter passing power Pmot_d calculated in step S1 to less than a predetermined value, and then proceeds to step S3. Here, in the limiting processing in step S5, the management ECU 71 limits the required inverter passing power Pmot_d, for example, by setting a high output threshold value Phigh as the required inverter passing power Pmot_d.

[0085] If the determination result in step S4 is NO, the management ECU 71 proceeds to step S6. In step S6, the management ECU 71 calculates the target converter passing power Pcnv_cmd and the target inverter passing power Pmot_cmd in an output priority mode that allows a larger inverter passing power than in the above-mentioned normal mode, as will be described with reference to Figures 6A and 6B, and proceeds to step S7.

[0086] 6A, 6B, 6C, and 6D are flowcharts showing procedures for calculating the target converter passing power Pcnv_cmd and the target inverter passing power Pmot_cmd in the output priority mode.

[0087] First, in step S11, the management ECU 71 acquires the first temperature margin T1_mar and the second temperature margin T2_mar from the first battery ECU 74 and the second battery ECU 75, respectively, and then proceeds to step S12.

[0088] Next, in step S12, the management ECU 71 acquires the first cooling margin PC1_mar and the second cooling margin PC2_mar from the cooling circuit ECU 76, and proceeds to step S13.

[0089] Next, in step S13, the management ECU 71 acquires the first output upper limit P1_max and the second output upper limit P2_max from the first battery ECU 74 and the second battery ECU 75, respectively, and proceeds to step S14.

[0090] Next, in step S14, the management ECU 71 obtains the closed circuit voltage CCV1 of the first battery B1 and the static voltage OCV2 of the second battery B2 from the first battery ECU 74 and the second battery ECU 75, respectively, and calculates the potential difference ΔV by subtracting the static voltage OCV2 of the second battery B2 from the closed circuit voltage CCV1 of the first battery B1, and then proceeds to step S15.

[0091] Next, in step S15, the management ECU 71 searches the operation table shown in FIG. 7 based on the acquired first temperature margin T1_mar, second temperature margin T2_mar, first cooling margin PC1_mar, and second cooling margin PC2_mar to obtain information regarding the prioritized output battery, output upper limit correction information, and charge / discharge stop information for the second battery B2, and proceeds to step S16.

[0092] FIG. 7 is a diagram showing an example of an operation table for determining the output and cooling mode of the battery based on the temperature margin and the cooling margin.

[0093] In FIG. 7, "temperature margin available" indicates that the first temperature margin T1_mar is equal to or greater than a predetermined first temperature margin threshold, or the second temperature margin T2_mar is equal to or greater than a predetermined second temperature margin threshold. "temperature margin unavailable" indicates that the first temperature margin T1_mar is less than the first temperature margin threshold, or the second temperature margin T2_mar is less than the second temperature margin threshold. "cooling margin available" indicates that the first cooling margin PC1_mar is equal to or greater than a predetermined first cooling margin threshold, or the second cooling margin PC2_mar is equal to or greater than a predetermined second cooling margin threshold. "cooling margin unavailable" indicates that the first cooling margin PC1_mar is less than the first cooling margin threshold, or the second cooling margin PC2_mar is less than the second cooling margin threshold.

[0094] Hereinafter, when the first temperature margin T1_mar is equal to or greater than the first temperature margin threshold, it is also referred to as a case where the first battery B1 has a temperature margin, and when the first temperature margin T1_mar is less than the first temperature margin threshold, it is also referred to as a case where the first battery B1 does not have a temperature margin. When the second temperature margin T2_mar is equal to or greater than the second temperature margin threshold, it is also referred to as a case where the second battery B2 has a temperature margin, and when the second temperature margin T2_mar is less than the second temperature margin threshold, it is also referred to as a case where the second battery B2 does not have a temperature margin. When the first cooling margin PC1_mar is equal to or greater than the first cooling margin threshold, it is also referred to as a case where the first battery B1 has a cooling margin, and when the first cooling margin PC1_mar is less than the first cooling margin threshold, it is also referred to as a case where the first battery B1 does not have a cooling margin. In addition, when the second cooling margin PC2_mar is equal to or greater than the second cooling margin threshold, this is also referred to as the second battery B2 having cooling margin, and when the second cooling margin PC2_mar is less than the second cooling margin threshold, this is also referred to as the second battery B2 having no cooling margin.

[0095] In the operation table shown in Fig. 7, "Charge / discharge stop: second battery" indicates that charging / discharging of the second battery B2 is temporarily stopped. Therefore, according to the example of the operation table shown in Fig. 7, when the second battery B2 has no temperature margin or cooling margin, charging / discharging of the second battery B2 is stopped.

[0096] The priority output battery refers to a battery that is given priority in outputting power up to its output upper limit. As described below, when the priority output battery is the first battery B1, the first battery B1 is given priority in outputting power up to its first output upper limit P1_max, and when the priority output battery is the second battery B2, the second battery B2 is given priority in outputting power up to its second output upper limit P2_max.

[0097] According to the example of the operation table shown in Fig. 7, when the first battery B1 has temperature margin and cooling margin, the first battery B1 is determined as the prioritized output battery, and when the second battery B2 has temperature margin and cooling margin, the second battery B2 is basically determined as the prioritized output battery. When both the first battery B1 and the second battery B2 have temperature margin and cooling margin, the first battery B1, which has a large heat capacity and is less likely to increase in temperature, is determined as the prioritized output battery. When the second battery B2 does not have at least either the temperature margin or the cooling margin, that is, when charging / discharging of the second battery B2 is stopped as described above, the first battery B1 is also determined as the prioritized output battery.

[0098] In the operation table shown in Fig. 7, "first output upper limit: DOWN" indicates that the first output upper limit P1_max of the first battery B1 is corrected downward. Therefore, according to the example of the operation table shown in Fig. 7, when the first battery B1 has neither temperature margin nor cooling margin, the first output upper limit P1_max is corrected downward.

[0099] Returning to FIG. 6A, in step S16, the management ECU 71 corrects the first output upper limit P1_max based on the output upper limit correction information acquired in step S15, and then proceeds to step S17.

[0100] In step S17, the management ECU 71 determines whether or not charging and discharging of the second battery B2 is stopped based on the charge / discharge stop information of the second battery B2 acquired in step S15. If the determination result in S17 is NO, the management ECU 71 proceeds to step S18, and if the determination result is YES, the management ECU 71 proceeds to step S31.

[0101] In step S18, the management ECU 71 determines whether or not the contactors 32p, 32n of the second battery B2 are currently on, i.e., whether or not the second battery B2 is connected to the second power circuit 3. If the determination result in S18 is NO, the management ECU 71 proceeds to step S19, and if the determination result is YES, the management ECU 71 proceeds to step S38.

[0102] Next, in step S19, the management ECU 71 judges whether the required inverter passing power Pmot_d acquired in step S1 is greater than the sum of the first output upper limit P1_max and the second output upper limit P2_max. If the judgment result in step S19 is YES, the management ECU 71 proceeds to step S20, executes limit processing to limit the required inverter passing power Pmot_d to less than a predetermined value, and then proceeds to step S21. Here, in the limit processing in step S20, the management ECU 71 limits the required inverter passing power Pmot_d by setting, for example, the sum of the first output upper limit P1_max and the second output upper limit P2_max as the required inverter passing power Pmot_d. If the judgment result in step S19 is NO, the management ECU 71 proceeds to step S21 without executing the limit processing as described above.

[0103] Next, in step S21, the management ECU 71 sets the required inverter passing power Pmot_d as the target inverter passing power Pmot_cmd, and proceeds to step S22.

[0104] Next, in step S22, the management ECU 71 determines whether or not the prioritized output battery acquired in step S15 is the first battery B1. If the determination result in step S22 is YES, the management ECU 71 proceeds to step S23, and if the determination result is NO, the management ECU 71 proceeds to step S26.

[0105] Next, in step S23, the management ECU 71 judges whether the required inverter passing power Pmot_d is greater than the first output upper limit P1_max. If the judgment result in step S23 is YES, the management ECU 71 proceeds to step S24, sets a value obtained by subtracting the first output upper limit P1_max from the required inverter passing power Pmot_d as the target converter passing power Pcnv_cmd, and proceeds to step S7 in Fig. 5. If the judgment result in step S23 is NO, the management ECU 71 proceeds to step S25, sets the value 0 as the target converter passing power Pcnv_cmd, and proceeds to step S7 in Fig. 5. As described above, when the first battery B1 is set as the priority output battery, the first battery B1 is given priority over the second battery B2, and power is output up to the first output upper limit P1_max.

[0106] Next, in step S26, the management ECU 71 determines whether the required inverter passing power Pmot_d is greater than the second output upper limit P2_max. If the determination result in step S26 is YES, the management ECU 71 proceeds to step S27, sets the second output upper limit P2_max as the target converter passing power Pcnv_cmd, and proceeds to step S7 in Fig. 5. If the determination result in step S26 is NO, the management ECU 71 proceeds to step S28, sets the required inverter passing power Pmot_d as the target converter passing power Pcnv_cmd, and proceeds to step S7 in Fig. 5. As described above, when the second battery B2 is set as the priority output battery, the second battery B2 is given priority over the first battery B1, and power is output up to the second output upper limit P2_max.

[0107] If the determination result in step S17 is YES, the management ECU 71 proceeds to step S31 and determines whether the potential difference ΔV between the first battery B1 and the second battery B2 calculated in step S14 is equal to or greater than a predetermined potential difference threshold ΔVth.

[0108] If the determination result in step S31 is YES, that is, if the second battery B2 has no temperature margin or cooling margin and the potential difference ΔV is equal to or greater than the potential difference threshold ΔVth, the management ECU 71 proceeds to step S32. In step S32, the management ECU 71 sets the target converter passing power Pcnv_cmd to a value of 0, that is, stops the voltage converter 5, and then proceeds to step S35. This stops the charging and discharging of the second battery B2. Furthermore, by stopping the charging and discharging of the second battery B2, the cooling of the second battery B2 is promoted, so that both the second temperature margin T2_mar and the second cooling margin PC2_mar gradually increase. After stopping the voltage converter 5 in step S35, when the second temperature margin T2_mar becomes equal to or greater than the second temperature margin threshold and the second cooling margin PC2_mar becomes equal to or greater than the second cooling margin threshold, the management ECU 71 sets a value other than 0 as the target converter passing power Pcnv_mot to restart driving of the voltage converter 5 (see steps S24, S27, and S28).

[0109] Next, in step S35, the management ECU 71 determines whether the required inverter passing power Pmot_d is greater than the first output upper limit P1_max of the first battery B1. If the determination result in step S35 is YES, the management ECU 71 proceeds to step S36, where it sets the first output upper limit P1_max as the target inverter passing power Pmot_cmd, and then proceeds to step S7 in Fig. 5. If the determination result in step S35 is NO, the management ECU 71 sets the required inverter passing power Pmot_d as the target inverter passing power Pmot_cmd, and then proceeds to step S7 in Fig. 5.

[0110] If the determination result of step S31 is NO, that is, the second battery B2 does not have at least one of the temperature margin and the cooling margin, and the potential difference ΔV is less than the potential difference threshold ΔVth, the management ECU 71 proceeds to step S33. In step S33, the management ECU 71 determines whether the contactors 32p, 32n of the second battery B2 are currently off, that is, whether the second battery B2 is connected to the second power circuit 3. If the determination result of step S33 is YES, that is, the second battery B2 has already been disconnected from the second power circuit 3, the management ECU 71 proceeds to step S32. If the determination result of step S33 is NO, that is, the second battery B2 has not yet been disconnected from the second power circuit 3, the management ECU 71 proceeds to step S34, where it transmits a command to the second battery ECU 75 to turn off the contactors 32p, 32n of the second battery B2, and then proceeds to step S32. In response to receiving this command, the second battery ECU 75 turns off the contactors 32p, 32n to disconnect the second battery B2 from the second power circuit 3. This stops the charging and discharging of the second battery B2. Furthermore, by stopping the charging and discharging of the second battery B2, the charging and discharging of the second battery B2 is stopped. Furthermore, by stopping the charging and discharging of the second battery B2, the cooling of the second battery B2 is promoted, so that both the second temperature reserve T2_mar and the second cooling reserve PC2_mar gradually increase.

[0111] In step S38, the management ECU 71 transmits a command to the second battery ECU 75 to turn on the contactors 32p, 32n of the second battery B2, and then proceeds to step S32. That is, after disconnecting the second battery B2 from the second power circuit 3 based on the command in step S34, the management ECU 71 turns on the contactors 32p, 32n and connects the second battery B2 to the second power circuit 3 in response to the second temperature margin T2_mar becoming equal to or greater than the second temperature margin threshold and the second cooling margin PC2_mar becoming equal to or greater than the second cooling margin threshold. Note that after transmitting the command to the second battery ECU 75 to turn on the contactors 32p, 32n in step S38, the vehicle runs only on the output power from the first battery B1 until the contactors 32p, 32n are actually turned on (i.e., until the determination result in step S18 is YES) (see steps S35 to S37).

[0112] As described above, when the operating mode is the output priority mode, the management ECU 71 controls the output power of the first battery B1 and the output power of the second battery B2 based on the required inverter passing power Pmot_d, the first cooling margin PC1_mar, the second cooling margin PC2_mar, the first temperature margin T1_mar, and the second temperature margin T2_mar.

[0113] Returning to FIG. 4, a procedure for controlling the first cooling output and the second cooling output by the cooling circuit ECU 76 will be described.

[0114] As described with reference to Fig. 5, when the operation mode in the power management process is the output priority mode (see step S6 in Fig. 5), a larger inverter passing power is permitted than when the operation mode is the normal mode (see step S3 in Fig. 5). Therefore, the heat generation amounts of the first battery B1 and the second battery B2 tend to be larger when the operation mode is the output priority mode than when the operation mode is the normal mode. Therefore, the cooling circuit ECU 76 changes the control algorithm for the first cooling output and the second cooling output depending on the operation mode in the power management process.

[0115] First, a case where the operation mode is the normal mode will be described. When the operating mode is the normal mode, the cooling circuit ECU 76 calculates a first control input (e.g., the duty ratio of the motor that drives the radiator fan) for the first cooling device 91 based on a known first basic cooling algorithm using the first battery temperature transmitted from the first battery ECU 74, the detection value of the first coolant temperature sensor, and the detection value of the outside air temperature sensor, so that the first battery temperature becomes a predetermined first target temperature, and controls the first cooling output by inputting this first control input to the first cooling device 91.

[0116] Furthermore, when the operating mode is the normal mode, the cooling circuit ECU 76 calculates a second control input (e.g., the duty ratio of the motor that drives the cooling fan) for the second cooling device 92 based on a known second basic cooling algorithm using the second battery temperature transmitted from the second battery ECU 75 and the detection value of the outside air temperature sensor so that the second battery temperature becomes a predetermined second target temperature, and controls the second cooling output by inputting this second control input to the second cooling device 92.

[0117] Next, a case where the operation mode is the output priority mode will be described. When the operation mode is the output priority mode, the cooling circuit ECU 76 controls the first cooling output based on the above-mentioned first basic cooling algorithm, the first temperature margin T1_mar, and the first cooling margin PC1_mar. More specifically, the cooling circuit ECU 76 first obtains information on the first cooling mode of the first battery B1 by searching the operation map shown in FIG. 7 based on the first temperature margin T1_mar and the first cooling margin PC1_mar. According to the example of the operation map in FIG. 7, when the first battery B1 has a cooling margin, the first cooling mode is "active cooling". When the first battery B1 does not have a cooling margin, the first cooling mode is "max cooling".

[0118] Next, the cooling circuit ECU 76 corrects the first control input calculated based on the above-mentioned first basic cooling algorithm according to the first cooling mode information acquired from the operation map of FIG. 7, and controls the first cooling output by inputting the corrected first control input to the first cooling device 91. When the first cooling mode is "active cooling", the cooling circuit ECU 76 corrects the first control input to the cooling performance improvement side by adding a correction value calculated based on the first temperature margin T1_mar to the first control input calculated based on the first basic cooling algorithm. Therefore, when the operation mode is the output priority mode and the first cooling mode is "active cooling", the cooling circuit ECU 76 increases the first cooling output compared to when the operation mode is the normal mode. Moreover, when the first cooling mode is "cooling max", the cooling circuit ECU 76 sets the first control input to the maximum value regardless of the calculation result of the first control input based on the first basic cooling algorithm. Therefore, when the operating mode is the output priority mode and the first cooling mode is "cooling max", the cooling circuit ECU 76 increases the first cooling output to the first maximum cooling output.

[0119] Also, when the operation mode is the output priority mode, the cooling circuit ECU 76 controls the second cooling output based on the above-mentioned second basic cooling algorithm, the second temperature margin T2_mar, and the second cooling margin PC2_mar. More specifically, the cooling circuit ECU 76 first obtains information on the second cooling mode of the second battery B2 by searching the operation map shown in FIG. 7 based on the second temperature margin T2_mar and the second cooling margin PC2_mar. According to the example of the operation map in FIG. 7, when the second battery B2 has a cooling margin, the second cooling mode is "active cooling". When the second battery B2 does not have a cooling margin, the second cooling mode is "max cooling".

[0120] Next, the cooling circuit ECU 76 corrects the second control input calculated based on the above-mentioned second basic cooling algorithm according to the second cooling mode information acquired from the operation map of FIG. 7, and controls the second cooling output by inputting the corrected second control input to the second cooling device 92. When the second cooling mode is "active cooling", the cooling circuit ECU 76 corrects the second control input to the cooling performance improvement side by adding a correction value calculated based on the second temperature margin T2_mar to the second control input calculated based on the second basic cooling algorithm. Therefore, when the operation mode is the output priority mode and the second cooling mode is "active cooling", the cooling circuit ECU 76 increases the second cooling output compared to when the operation mode is the normal mode. Moreover, when the second cooling mode is "cooling max", the cooling circuit ECU 76 sets the second control input to the maximum value regardless of the calculation result of the second control input based on the second basic cooling algorithm. Therefore, when the operating mode is the output priority mode and the second cooling mode is "cooling max", the cooling circuit ECU 76 increases the second cooling output to the second maximum cooling output.

[0121] The power supply system 1 according to this embodiment provides the following advantages. (1) In the power supply system 1, a first power circuit 2 having a first battery B1 is connected to a second power circuit 3 having a second battery B2 whose operating voltage range for the closed circuit voltage overlaps with that of the first battery B1 and whose static voltage is lower than that of the first battery B1 by a voltage converter 5, and the first power circuit 2 is connected to a drive motor M by a power converter 43. The management ECU 71 acquires a potential difference ΔV between the closed circuit voltage CCV1 of the first battery B1 and the static voltage OCV2 of the second battery B2, a second temperature margin T2_mar of the second battery B2, and a second cooling margin PC2_mar of the second battery B2. The management ECU 71 also stops the voltage converter 5 when at least one of the second temperature margin T2_mar and the second cooling margin PC2_mar is less than the respective thresholds and the potential difference ΔV is equal to or greater than the potential difference threshold ΔVth. If the voltage converter 5 is stopped here, it is possible to prevent at least a current from flowing to the second battery B2, and therefore the temperature of the second battery B2 can be reduced thereafter. Thus, the power supply system 1 can prevent unintended charging and discharging from the second battery B2 in a high temperature state. In particular, the power supply system 1 determines the timing to stop the voltage converter 5 in consideration of not only the second temperature margin T2_mar but also the second cooling margin PC2_mar, and thereby can stop the voltage converter 5 at an appropriate timing in consideration of the cooling performance of the second battery B2 by the second cooling device 92. Furthermore, in the power supply system 1, when the potential difference ΔV is equal to or greater than the potential difference threshold ΔVth, by only stopping the voltage converter 5, the second battery B2 can be charged and discharged promptly thereafter as necessary.

[0122] (2) After stopping the voltage converter 5, the management ECU 71 restarts driving the voltage converter 5 in response to both the second temperature margin T2_mar and the second cooling margin PC2_mar reaching or exceeding their respective thresholds. This makes it possible to more reliably prevent unintended charging and discharging from the second battery B2 in a high temperature state.

[0123] (3) The management ECU 71 disconnects the second battery B2 from the second power circuit 3 when at least one of the second temperature margin T2_mar and the second cooling margin PC2_mar is less than the corresponding threshold and the potential difference ΔV is less than the potential difference threshold ΔVth. Here, by disconnecting the second battery B2 from the second power circuit 3, charging and discharging of the second battery B2 can be reliably prevented, and the temperature of the second battery B2 can be reduced thereafter. Thus, the power supply system 1 can prevent unintended charging and discharging from the second battery B2 in a high temperature state. In particular, the power supply system 1 determines the timing to disconnect the second battery B2 from the second power circuit 3 taking into account not only the second temperature margin T2_mar but also the second cooling margin PC2_mar, and can disconnect the second battery B2 from the second power circuit 3 at an appropriate timing taking into account the cooling performance of the second battery B2 by the second cooling device 92.

[0124] (4) After disconnecting the second battery B2 from the second power circuit 3, the management ECU 71 connects the second battery B2 to the second power circuit 3 in response to both the second temperature margin T2_mar and the second cooling margin PC2_mar reaching or exceeding their respective thresholds. This makes it possible to more reliably prevent unintended charging and discharging from the second battery B2 in a high temperature state.

[0125] (5) When the operation mode in the management process is the power priority mode and the second cooling reserve capacity PC2_mar is equal to or greater than the second cooling reserve capacity threshold, the cooling circuit ECU 76 increases the second cooling output more than when the operation mode is the normal mode. This allows the second temperature reserve capacity T2_mar to be increased quickly, thereby increasing the opportunities to charge and discharge the second battery B2 in the power priority mode.

[0126] Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment. The detailed configuration may be appropriately changed within the scope of the spirit of the present invention. [Explanation of symbols]

[0127] V…Vehicle M: Drive motor (rotating electric machine) 1. Power supply system 2...1st power circuit B1: First battery (first power storage device) 3…Second power circuit B2: Second battery (second power storage device) 4...Load circuit 43...Power converter 5…Voltage converter 9…Cooling circuit 7...Electronic control units 71...Management ECU (power control means, potential difference acquisition means) 72...Motor ECU (power control means) 73...Converter ECU (power control means) 74...First battery ECU (potential difference acquisition means) 75...Second battery ECU (potential difference acquisition means, temperature acquisition means, temperature margin acquisition means) 76...Cooling circuit ECU (cooling output control means, cooling margin acquisition means) 81...first battery sensor unit (potential difference acquiring means) 82...second battery sensor unit (potential difference acquisition means, temperature acquisition means, temperature margin acquisition means) 91...1st cooling device 92…Second cooling device (cooling device)

Claims

1. a first power circuit having a first power storage device; a second power circuit including a second storage device whose working voltage range for a closed circuit voltage overlaps with that of the first storage device and whose static voltage is lower than that of the first storage device; a voltage converter that converts a voltage between the first power circuit and the second power circuit; a power converter that converts power between the first power circuit and a rotating electric machine; a power control unit that controls charging and discharging of the first and second power storage devices by operating the voltage converter and the power converter; a potential difference acquiring unit that acquires a potential difference between the first power storage device and the second power storage device; A cooling device that cools the second power storage device; A cooling output control means for controlling a cooling output by the cooling device; a temperature acquisition means for acquiring a temperature of the second power storage device, a temperature margin acquiring means for acquiring a temperature margin that increases or decreases according to a difference between an upper limit temperature of the second power storage device and a temperature of the power storage device; a cooling margin acquisition means for acquiring a cooling margin that increases or decreases according to a difference between a maximum cooling output of the cooling device and the cooling output of the cooling device, A power supply system characterized in that the power control means stops the voltage converter when at least one of the temperature margin and the cooling margin is less than a respective threshold value and the potential difference is equal to or greater than a potential difference threshold value.

2. 2. The power supply system according to claim 1, wherein the power control means starts driving the voltage converter after stopping the voltage converter in response to both the temperature margin and the cooling margin becoming equal to or greater than the corresponding threshold value.

3. 3. The power supply system according to claim 1, wherein the power control means disconnects the second storage device from the second power circuit when at least one of the temperature margin and the cooling margin is less than the corresponding threshold value and the potential difference is less than the potential difference threshold value.

4. a first power circuit having a first power storage device; a second power circuit including a second storage device whose working voltage range for a closed circuit voltage overlaps with that of the first storage device and whose static voltage is lower than that of the first storage device; a voltage converter that converts a voltage between the first power circuit and the second power circuit; a power converter that converts power between the first power circuit and a rotating electric machine that generates a propulsive force; a power control unit that controls charging and discharging of the first and second power storage devices by operating the voltage converter and the power converter; a potential difference acquiring unit that acquires a potential difference between the first power storage device and the second power storage device; A cooling device that cools the second power storage device; A cooling output control means for controlling a cooling output by the cooling device; a temperature acquisition means for acquiring a temperature of the second power storage device, a temperature margin acquiring means for acquiring a temperature margin that increases or decreases according to a difference between an upper limit temperature of the second power storage device and a temperature of the power storage device; a cooling margin acquisition means for acquiring a cooling margin that increases or decreases according to a difference between a maximum cooling output of the cooling device and the cooling output of the cooling device, The power supply system is characterized in that the power control means disconnects the second storage device from the second power circuit when at least one of the temperature margin and the cooling margin is less than a threshold value for each and the potential difference is less than a potential difference threshold.

5. 5. The power supply system according to claim 4, wherein the power control means, after disconnecting the second storage device from the second power circuit, connects the second storage device to the second power circuit in response to both the temperature margin and the cooling margin becoming equal to or greater than the respective threshold values.

6. 6. The power supply system according to claim 4, wherein the power control means stops the voltage converter when at least one of the temperature margin and the cooling margin is less than the threshold value for each and the potential difference is equal to or greater than the potential difference threshold.

7. the power control means controls charging and discharging of the first and second power storage devices in a normal mode or an output priority mode that allows a larger output from the first power circuit to the rotating electric machine than in the normal mode, 7. The power supply system according to claim 1, wherein when the operation mode of the power control means is the output priority mode and the cooling margin is equal to or greater than a cooling margin threshold, the cooling output control means increases the cooling output compared to when the operation mode is the normal mode.

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