Power System

Abstract

This invention provides a power supply system in which unintended discharge from a second energy storage device can be suppressed in a voltage converter that connects a high-voltage first energy storage device to a low-voltage second energy storage device. The power supply system includes: a first power circuit having a first battery and a first power line; a second power circuit having a second battery and a second power line; a voltage converter that converts voltage; a power converter that converts power; a first voltage acquisition member that acquires a first closed-circuit voltage lower limit CCVmin1 of the first battery; a second voltage acquisition member that acquires a second closed-circuit voltage lower limit CCVmin2 of the second battery; and a power control member that operates the second power circuit, etc., based on power demand; and, when the second battery is subject to an output limitation requirement, if the voltage difference between the first closed-circuit voltage lower limit CCVmin1 and the second closed-circuit voltage lower limit CCVmin2 does not reach a first voltage difference threshold A, the power control member disconnects the second battery from the second power line.

Description

Technical Field

[0001] This invention relates to a power supply system. More specifically, it relates to a power supply system for an electric vehicle having two energy storage devices. Background Technology

[0002] In recent years, there has been a surge in the development of electric vehicles, such as electric conveyors powered by a drive motor and hybrid vehicles powered by both a drive motor and an internal combustion engine. These electric vehicles also incorporate power supply units such as energy storage devices (batteries and capacitors) or fuel cells to supply electrical energy to the drive motor. Furthermore, in recent years, electric vehicles equipped with multiple power supply units exhibiting different characteristics have also been developed.

[0003] Patent Document 1 discloses a power supply system for an electric vehicle, comprising: a power circuit that connects a drive unit, consisting of a drive motor or inverter, to a first energy storage device; a second energy storage device connected to the power circuit via a voltage converter; and a control device that performs switching control on the voltage converter. The control device sets a target current corresponding to the current flowing through the voltage converter based on a request from the driver, and performs switching control on the voltage converter to achieve the target current. It then combines the power output from the first energy storage device and the power output from the second energy storage device and supplies it to the drive motor.

[0004] [Existing technical documents]

[0005] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-169311 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] In a power system like this one, where two energy storage devices are connected by a voltage converter, the power output from the second energy storage device can generally be controlled by switching the voltage converter. However, when the drive motor requires a large amount of power, such as during acceleration, the current flowing in the first energy storage device increases, and the closed-circuit voltage of the first energy storage device becomes lower than the static voltage of the second energy storage device. At this time, the second energy storage device starts discharging, and an unexpected current flows from the second energy storage device side to the first energy storage device side in the voltage converter.

[0009] The purpose of this invention is to provide a power supply system that can suppress unintended discharge from the second energy storage device in a voltage converter that connects a high-voltage first energy storage device and a low-voltage second energy storage device.

[0010] [Technical means to solve the problem]

[0011] (1) The power supply system of the present invention (e.g., power supply system 1 below) comprises: a first power circuit (e.g., first power circuit 2 below), having a first energy storage device (e.g., first battery B1 below) and a first power line (e.g., first power line 21p, 21n below) to which the first energy storage device is connected; a second power circuit (e.g., second power circuit 3 below), having a second energy storage device (e.g., second battery B2 below) and a second power line (e.g., second power line 31p, 31n below) to which the second energy storage device is connected, wherein the operating voltage range of the second energy storage device for closed-circuit voltage overlaps with that of the first energy storage device and the static voltage is lower than that of the first energy storage device; a voltage converter (e.g., voltage converter 5 below), which converts voltage between the first power line and the second power line; a power converter (e.g., power converter 43 below), which converts power between the first power line and a rotary motor (e.g., drive motor M below); and a first voltage acquisition member (e.g., electronic control below). The power system comprises: a unit group 7 and a first battery sensor unit 81, which acquires a first voltage of the first energy storage device (e.g., the first closed-circuit voltage lower limit CCVmin1 described below); a second voltage acquisition member (e.g., the electronic control unit group 7 and the second battery sensor unit 82 described below), which acquires a second voltage of the second energy storage device (e.g., the second closed-circuit voltage lower limit CCVmin2 described below); a power demand acquisition member (e.g., the pedal type P and the management ECU 71 described below), which acquires the power demand of the rotary motor; and a power control member (e.g., the electronic control unit group 7 described below), which operates the power converter, the voltage converter and the second power circuit according to the power demand; the power system is characterized in that: when the second energy storage device is subject to an output limiting requirement, if the voltage difference between the first voltage and the second voltage does not reach a first voltage difference threshold (e.g., the first voltage difference threshold A described below), the power control member disconnects the second energy storage device from the second power line.

[0012] (2) Preferably, when the voltage difference does not reach the first voltage difference threshold during the period when the second energy storage device is subject to an output limitation requirement, the power control component operates the voltage converter to make the absolute value of the input and output power of the second energy storage device reach below the power threshold (e.g., power threshold B below), and when the input and output power of the second energy storage device reaches below the power threshold, the second energy storage device is disconnected from the second power line.

[0013] (3) In this case, it is preferable that the power control component connects the second energy storage device to the second power line when the output limitation of the second energy storage device is released after the second energy storage device is disconnected from the second power line, or when the voltage difference reaches or exceeds the second voltage difference threshold (e.g., the second voltage difference threshold C below).

[0014] (4) In this case, it is preferable that the first and second voltage acquisition components acquire the lower limit of the closed-circuit voltage of the first and second energy storage devices respectively, and use it as the first and second voltages.

[0015] (The effect of the invention)

[0016] (1) In the power supply system of the present invention, a first power circuit and a second power circuit are connected by a voltage converter, and the first power circuit is connected to a rotating motor by a power converter. The first power circuit has a first energy storage device, and the second power circuit has a second energy storage device. The operating voltage range of the second energy storage device for closed-circuit voltage overlaps with that of the first energy storage device, and its static voltage is lower than that of the first energy storage device. The power control component operates the power converter, the voltage converter, and the second power circuit based on the power demand of the rotating motor. In such a power supply system, for example, when the power demand increases according to acceleration requirements, the power control component operates the power converter or the voltage converter and combines the power output from the first energy storage device with the power output from the second energy storage device to supply the output power corresponding to the power demand from the power converter to the rotating motor. Here, if it is desired to suppress (including prohibit) the discharge from the second energy storage device for some reason, the power control component operates the voltage converter or the power converter to provide all or most of the power demand through the power output from the first energy storage device. However, when the current flowing in the first energy storage device increases, the closed-circuit voltage of the first energy storage device becomes lower than the static voltage of the second energy storage device, resulting in unexpected power output from the second energy storage device. To address this, in this invention, during periods when the second energy storage device is subject to output limitation requirements, if the voltage difference between the first voltage of the first energy storage device and the second voltage of the second energy storage device does not reach a first voltage difference threshold, the second energy storage device is disconnected from the second power line of the second power circuit. Therefore, according to this invention, the second energy storage device can be reliably disconnected from the second power line and even the first power circuit, thus reliably suppressing unexpected discharge from the second energy storage device.

[0017] Furthermore, Japanese Patent Application Publication No. 2020-162251 disclosed a technique that suppresses unintended discharges from the second energy storage device by operating a power converter to ensure that the output power of the first energy storage device does not exceed a limit calculated based on the state of the second energy storage device. Therefore, according to the technique disclosed in Japanese Patent Application Publication No. 2020-162251, it is necessary to limit the output power of the first energy storage device, which may result in a situation where the required power cannot be supplied to the rotating motor. In contrast, according to the present invention, it is not necessary to suppress the output power of the first energy storage device; therefore, not only can unintended discharges from the second energy storage device be suppressed, but the required power can also be continuously supplied to the rotating motor.

[0018] (2) In this invention, when the voltage difference does not reach the first voltage difference threshold during the period when the second energy storage device is subject to an output limitation requirement, the power control component operates the voltage converter to bring the absolute value of the input and output power of the second energy storage device below the power threshold. Once the input and output power of the second energy storage device falls below the power threshold, the second energy storage device is disconnected from the second power line. Thus, by disconnecting the second energy storage device from the second power line while a discharge current or a charging current is flowing in the second energy storage device, the impact on vehicle behavior can be suppressed.

[0019] (3) In this invention, the power control component connects the second energy storage device to the second power line when the output limitation of the second energy storage device is released after the second energy storage device is disconnected from the second power line, or when the voltage difference reaches or exceeds the second voltage difference threshold. This allows for rapid power supply from the second energy storage device to the first power circuit when needed.

[0020] (4) In this invention, the first and second voltage acquisition members acquire the lower limits of the closed-circuit voltages of the first and second energy storage devices, respectively, as the first and second voltages. This allows the second energy storage device to be disconnected from the second power line at an appropriate time, thereby effectively suppressing unintended discharges from the second energy storage device. Attached Figure Description

[0021] Figure 1 A diagram illustrating the configuration of a vehicle equipped with a power supply system according to an embodiment of the present invention.

[0022] Figure 2 This is a comparison chart of the operating voltage ranges of the first and second batteries.

[0023] Figure 3 This diagram illustrates an example of the circuit configuration of a voltage converter.

[0024] Figure 4 A flowchart illustrating the specific procedures for power management processing.

[0025] Figure 5 This is a flowchart illustrating the procedure for calculating the target power in a voltage converter.

[0026] Figure 6 A flowchart illustrating the specific procedure for blocking determination and processing is provided.

[0027] Figure 7 A flowchart illustrating the procedure for calculating the lower limit of the first closed-circuit voltage of the first cell.

[0028] Figure 8 A flowchart illustrating the procedure for calculating the lower limit of the second closed-circuit voltage of the second battery.

[0029] Figure 9 A flowchart illustrating the specific procedure for blocking determination and processing is provided. Detailed Implementation

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0031] Figure 1 The diagram illustrates the configuration of an electric vehicle V (hereinafter referred to as "vehicle") equipped with the power system 1 of this embodiment.

[0032] The vehicle V includes: a drive wheel W; a drive motor M connected to the drive wheel W as a rotary motor; and a power system 1 that supplies and receives power between the drive motor M and the first battery B1 and the second battery B2 described below. In this embodiment, the vehicle V is primarily described as a vehicle that accelerates and decelerates using the power generated by the drive motor M, but the invention is not limited to this. The vehicle V can also be a so-called hybrid vehicle equipped with a drive motor M and an engine as power sources.

[0033] The drive motor M is connected to the drive wheel W via a power transmission mechanism (not shown). The torque generated by the drive motor M, supplied with three-phase AC power from the power system 1, is transmitted to the drive wheel W via the power transmission mechanism (not shown), causing the drive wheel W to rotate and propelling the vehicle V. Furthermore, when the vehicle V decelerates, the drive motor M functions as a generator, producing regenerative power and applying a regenerative braking torque corresponding to the magnitude of this regenerative power to the drive wheel W. The regenerative power generated by the drive motor M appropriately charges the batteries B1 and B2 of the power system 1.

[0034] The power supply system 1 includes: a first power circuit 2 having a first battery B1; a second power circuit 3 having a second battery B2; a voltage converter 5 connecting the first power circuit 2 and the second power circuit 3; a load circuit 4 having various electrical loads including a drive motor M; and an electronic control unit group 7 as a power control component, which controls the flow of power in the power circuits 2, 3, and 4 by operating the power circuits 2, 3, and 4 and the voltage converter 5. The electronic control unit group 7 includes a management ECU 71, a motor ECU 72, a converter ECU 73, a first battery ECU 74, and a second battery ECU 75, which are respectively used as a computer.

[0035] The first battery B1 is a secondary battery capable of simultaneously converting chemical energy into electrical energy through discharge and electrical energy into chemical energy through charging. The following description will use a so-called lithium-ion battery, which charges and discharges by the movement of lithium ions between electrodes, as this first battery B1; however, the present invention is not limited thereto.

[0036] In the first battery B1, a first battery sensor unit 81 is provided for inferring the internal state of the first battery B1. The first battery sensor unit 81 is composed of multiple sensors that detect physical quantities such as the charge rate (expressed as a percentage of battery capacity) or temperature of the first battery B1, which are then acquired in the first battery ECU 74, and send signals corresponding to the detected values ​​to the first battery ECU 74. More specifically, the first battery sensor unit 81 is composed of a voltage sensor for detecting the terminal voltage of the first battery B1, a current sensor for detecting the current flowing in the first battery B1, and a temperature sensor for detecting the temperature of the first battery B1.

[0037] The second battery B2 is a secondary battery capable of both discharging (converting chemical energy into electrical energy) and charging (converting electrical energy into chemical energy). Hereinafter, a lithium-ion battery, which charges and discharges by the movement of lithium ions between electrodes, will be used as the second battery B2; however, the present invention is not limited thereto. For example, a capacitor may also be used as the second battery B2.

[0038] In the second battery B2, a second battery sensor unit 82 is provided for inferring the internal state of the second battery B2. The second battery sensor unit 82 consists of multiple sensors that detect physical quantities such as the charging rate or temperature of the second battery B2, which are then acquired in the second battery ECU 75, and send signals corresponding to the detected values ​​to the second battery ECU 75. More specifically, the second battery sensor unit 82 consists of a voltage sensor for detecting the terminal voltage of the second battery B2, a current sensor for detecting the current flowing through the second battery B2, and a temperature sensor for detecting the temperature of the second battery B2.

[0039] Here, the characteristics of the first battery B1 are compared with those of the second battery B2.

[0040] Compared to battery B2, battery B1 has a lower output weight density and a higher energy weight density. Furthermore, battery B1 has a larger capacity than battery B2. In other words, battery B1 is superior to battery B2 in terms of energy weight density. Energy weight density refers to the amount of electricity per unit weight [Wh / kg], while output weight density refers to the amount of electricity per unit weight [W / kg]. Therefore, battery B1, with its superior energy weight density, is a capacitor-type energy storage device primarily designed for high capacitance, while battery B2, with its superior output weight density, is an output-type energy storage device primarily designed for high output. Therefore, in power system 1, battery B1 is used as the main power source, and battery B2 is used as an auxiliary power source to assist battery B1.

[0041] Figure 2 This is a comparison diagram of the operating voltage ranges of the first battery B1 and the second battery B2 in power system 1. Figure 2 In the diagram, the left side shows the operating voltage range of the first battery B1, and the right side shows the operating voltage range of the second battery B2. Figure 2 In the diagram, the horizontal axis represents the current flowing in the battery, and the vertical axis represents the battery voltage.

[0042] like Figure 2 As shown, the static voltage (i.e., the voltage when no current flows through the battery, also known as the open-circuit voltage) of batteries B1 and B2 increases with the charging rate. Therefore, the upper limit of the operating voltage range for the static voltage of batteries B1 and B2 is the static voltage at the maximum charging rate (e.g., 100%), and the lower limit is the static voltage at the minimum charging rate (e.g., 0%). Figure 2 As shown, the upper limit of the operating voltage range of the second battery B2 relative to the static voltage is lower than the upper limit of the operating voltage range of the first battery B1 relative to the static voltage. Therefore, during the operation of the vehicle V, the static voltage of the second battery B2 is essentially maintained at a lower level than that of the first battery B1.

[0043] like Figure 2As shown, the closed-circuit voltage (i.e., the voltage when current flows through the battery) of batteries B1 and B2 also exhibits the characteristic that it increases with the higher the charging rate. Furthermore, batteries B1 and B2 possess internal resistance, therefore their closed-circuit voltages have the following characteristics: the larger the discharge current, the lower the voltage from the static state; conversely, the larger the charging current, the higher the voltage from the static state. Therefore, the upper limit of the operating voltage range for closed-circuit voltage of 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 closed-circuit voltage of batteries B1 and B2 encompasses the operating voltage range for each static voltage. Figure 2 As shown, the operating voltage range of the first battery B1 for closed-circuit voltage overlaps with that of the second battery B2 for closed-circuit voltage.

[0044] Furthermore, excessive charging current will accelerate the degradation of batteries B1 and B2. Therefore, the upper limit of the operating voltage range for closed-circuit voltage of batteries B1 and B2 is set based on their condition to prevent degradation. This upper limit of the operating voltage range for closed-circuit voltage of batteries B1 and B2 will be referred to as the degradation upper limit voltage.

[0045] Furthermore, if the discharge current is too high, it will accelerate the degradation of batteries B1 and B2. Therefore, the lower limit of the operating voltage range of batteries B1 and B2 relative to the closed-circuit voltage is set based on the state of batteries B1 and B2 to prevent degradation of batteries B1 and B2. Hereinafter, the lower limit of the operating voltage range of batteries B1 and B2 relative to the closed-circuit voltage will also be referred to as the degradation lower limit voltage.

[0046] Return to Figure 1 The first power circuit 2 includes: a first battery B1; first power lines 21p and 21n, which connect the positive and negative terminals of the first battery B1 to the positive and negative terminals of the high-voltage side of the voltage converter 5; and a first positive contactor 22p and a first negative contactor 22n, which are disposed on the first power lines 21p and 21n.

[0047] The first contactors 22p and 22n are normally open. They open when there is no external command signal input, thus cutting off the connection between the two electrodes of the first battery B1 and the first power lines 21p and 21n. They close when a command signal is input, thus connecting the first battery B1 to the first power lines 21p and 21n. The first contactors 22p and 22n open and close according to the command signal sent from the first battery ECU 74. Additionally, the first positive contactor 22p is a pre-charge contactor, which has a pre-charge resistor to mitigate the inrush current from the multiple smoothing capacitors installed in the first power circuit 2 or load circuit 4, etc.

[0048] The second power circuit 3 includes: a second battery B2; second power lines 31p and 31n, which connect the positive and negative terminals of the second battery B2 to the positive and negative terminals of the low-voltage side of the voltage converter 5; a second positive contactor 32p and a second negative contactor 32n, which are disposed on the second power lines 31p and 31n; and a current sensor 33, which is disposed on the second power line 31p.

[0049] The second contactors 32p and 32n are normally open. They open when there is no external command signal input, thereby cutting off the conduction between the two electrodes of the second battery B2 and the second power lines 31p and 31n (i.e., disconnecting the second battery B2 from the second power lines 31p and 32n). They close when a command signal is input, thereby connecting the second battery B2 to the second power lines 31p and 31n. The second contactors 32p and 32n open and close according to the command signal sent from the second battery ECU 75. Additionally, the second positive contactor 32p is a pre-charge contactor with a pre-charge resistor, used to mitigate the inrush current from the multiple smoothing capacitors installed in the first power circuit 2 or load circuit 4, etc.

[0050] The current sensor 33 sends a detection signal corresponding to the current flowing through it to the converter ECU 73. The current flowing through it is the current flowing in the second power line 31p, i.e., the current flowing in the voltage converter 5. In addition, in this embodiment, the direction of the current flowing through it is set to positive from the side of the second power circuit 3 to the side of the first power circuit 2, and negative from the side of the first power circuit 2 to the side of the second power circuit 3.

[0051] The load circuit 4 includes: a vehicle auxiliary machine 42; a power converter 43 connected to the drive motor M; and load power lines 41p and 41n that connect the vehicle auxiliary machine 42 and the power converter 43 to the first power circuit 2.

[0052] The vehicle auxiliary unit 42 consists of multiple electrical loads, including a battery heater, an air compressor, a DC-DC converter, and an on-board charger. The vehicle auxiliary unit 42 is connected to the first power lines 21p and 21n of the first power circuit 2 via load power lines 41p and 41n, and operates by consuming power from the first power lines 21p and 21n. Information related to the operating status of the various electrical loads constituting the vehicle auxiliary unit 42 is sent, for example, to the management ECU 71.

[0053] The power converter 43 is connected to the first power lines 21p and 21n in parallel with the vehicle auxiliary equipment 42 via load power lines 41p and 41n. The power converter 43 converts power between the first power lines 21p and 21n and the drive motor M. The power converter 43 is, for example, a pulse width modulation (PWM) inverter that uses a pulse width modulation method and has a bridging circuit composed of multiple switching elements (e.g., insulated gate bipolar transistors, IGBTs) to convert DC power to AC power. The power converter 43 has its DC input and output sides connected to the first power lines 21p and 21n, and its AC input and output sides connected to the coils of the U-phase, V-phase, and W-phase of the drive motor M. The power converter 43 converts the DC power of the first power lines 21p and 21n into three-phase AC power and supplies it to the drive motor M by turning on / off the switching elements of each phase according to the gate drive signal generated from the gate drive circuit (not shown) of the motor ECU 72 at a predetermined time, or converts the three-phase AC power supplied from the drive motor M into DC power and supplies it to the first power lines 21p and 21n.

[0054] Voltage converter 5 connects the first power circuit 2 and the second power circuit 3, and converts the voltage between the two circuits 2 and 3. This voltage converter 5 uses a known boost circuit.

[0055] Figure 3 This diagram illustrates an example of the circuit configuration of voltage converter 5. Voltage converter 5 connects the first power lines 21p and 21n connected to the first battery B1 with the second power lines 31p and 31n connected to the second battery B2, and converts the voltage between the first power lines 21p and 21n and the second power lines 31p and 31n. Voltage converter 5 is a full-bridge DC-DC converter, constructed 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 and 56n, high-voltage side terminals 57p and 57n, and a smoothing capacitor (not shown).

[0056] Low-voltage side terminals 56p and 56n are connected to the second power line 31p and 31n, and high-voltage side terminals 57p and 57n are connected to the first power line 21p and 21n. Negative busbar 55 is the wiring that connects the low-voltage side terminal 56n to the high-voltage side terminal 57n.

[0057] One end of the first reactor L1 is connected to the low-voltage side terminal 56p, and the other end is connected to the 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 possess a known power switching element such as an IGBT or a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), and a return-current diode connected to this power switching element. The high-arm element 53H and the low-arm element 53L are connected in series between the high-voltage side terminal 57p and the negative bus 55 in the aforementioned order.

[0058] The collector of the power switching element in the first high-arm element 53H is connected to the high-voltage side terminal 57p, and its emitter is connected to the collector of the first low-arm element 53L. The emitter of the power switching element in the first low-arm element 53L is connected to the negative bus 55. The forward direction of the return diode in the first high-arm element 53H is from the first reactor L1 toward the high-voltage side terminal 57p. Similarly, the forward direction of the return diode in the first low-arm element 53L is from the negative bus 55 toward the first reactor L1.

[0059] One end of the second reactor L2 is connected to the low-voltage side terminal 56p, and the other end is connected to the 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 possess a known power switching element such as an IGBT or a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), and a return-current diode connected to this 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 the aforementioned order.

[0060] The collector of the power switching element in the second high-arm element 54H is connected to the high-voltage side terminal 57p, and its emitter is connected to the collector of the second low-arm element 54L. The emitter of the power switching element in the second low-arm element 54L is connected to the negative bus 55. The forward direction of the return diode in the second high-arm element 54H is from the second reactor L2 toward the high-voltage side terminal 57p. Similarly, the forward direction of the return diode in the second low-arm element 54L is from the negative bus 55 toward the second reactor L2.

[0061] The voltage converter 5 drives the first high arm element 53H and the second low arm element 54L, and alternately turns on / off the first low arm element 53L and the second high arm element 54H, according to the gate drive signal generated from the gate drive circuit (not shown) of the converter ECU73 at a predetermined time, thereby converting the voltage between the first power lines 21p, 21n and the second power lines 31p, 31n.

[0062] For reference Figure 2 As explained, during the operation of vehicle V, the static voltage of the second battery B2 is maintained at a level lower than that of the first battery B1. Therefore, the voltage of the first power lines 21p and 21n is generally higher than that of the second power lines 31p and 31n. Therefore, when using both the power output from the first battery B1 and the power output from the second battery B2 to drive the drive motor M, the converter ECU 73 operates the voltage converter 5 to perform a boost function. The boost function refers to boosting the power of the second power lines 31p and 31n connected to the low-voltage side terminals 56p and 56n and outputting it to the first power lines 21p and 21n connected to the high-voltage side terminals 57p and 57n, thereby allowing positive current to flow from the second power lines 31p and 31n side to the first power lines 21p and 21n side. Furthermore, when suppressing the discharge of the second battery B2 and using only the power output from the first battery B1 to drive the drive motor M, the converter ECU73 disconnects the voltage converter 5 to prevent current from flowing from the first power lines 21p and 21n to the second power lines 31p and 31n. However, in this case, when the voltage of the second power lines 31p and 31n is higher than the voltage of the first power lines 21p and 21n, the second battery B2 sometimes starts to discharge, and positive current flows from the second power lines 31p and 31n to the first power lines 21p and 21n via the return diodes of the high-arm elements 53H and 54H.

[0063] Additionally, when charging the first battery B1 or the second battery B2 using regenerative power output from the drive motor M to the first power lines 21p and 21n during deceleration, the converter ECU73 operates the voltage converter 5 to perform a step-down function. The step-down function refers to reducing the voltage of the first power lines 21p and 21n connected to the high-voltage side terminals 57p and 57n, and outputting it to the second power lines 31p and 31n connected to the low-voltage side terminals 56p and 56n. This causes a negative current to flow from the first power line 21p and 21n side to the second power line 31p and 31n side.

[0064] Return to Figure 1The first battery ECU 74 is a computer primarily responsible for monitoring the state of the first battery B1 and controlling the opening and closing operations of contactors 22p and 22n in the first power circuit 2. Based on a known algorithm using detection values ​​sent from the first battery sensor unit 81, the first battery ECU 74 calculates various parameters representing the internal state of the first battery B1. More specifically, it calculates the cell voltage of each cell constituting the first battery B1, the temperature of the first battery B1, the internal resistance of the first battery B1, the closed-circuit voltage of the first battery B1, the upper limit voltage of the first battery B1's degradation, the lower limit voltage of the first battery B1's degradation, the current of the first battery B1, the first output limit (which is the upper limit of the power that can be output from the first battery B1), and the charging rate of the first battery B1, etc. Information related to the parameters representing the internal state of the first battery B1 obtained in the first battery ECU 74 is, for example, sent to the management ECU 71.

[0065] The second battery ECU 75 is a computer primarily responsible for monitoring the state of the second battery B2 and controlling the opening and closing of contactors 32p and 32n in the second power circuit 3. Based on a known algorithm using detection values ​​sent from the second battery sensor unit 82, the second battery ECU 75 calculates various parameters representing the internal state of the second battery B2. More specifically, it calculates the cell voltage of each cell constituting the second battery B2, the temperature of the second battery B2, the internal resistance of the second battery B2, the closed-circuit voltage of the second battery B2, the upper limit voltage of the second battery B2's degradation, the lower limit voltage of the second battery B2's degradation, the current of the second battery B2, the second output upper limit (which is the upper limit of the power that can be output from the second battery B2), and the charging rate of the second battery B2, etc. Information related to the parameters representing the internal state of the second battery B2 obtained in the second battery ECU 75 is, for example, sent to the management ECU 71.

[0066] The management ECU 71 is the computer that primarily manages the power flow of the entire power system 1. The management ECU 71 performs operations as described below. Figure 4 The described power management process generates a torque command signal and a power transmission command signal. The torque command signal is equivalent to a command for the torque generated by the drive motor M, and the power transmission command signal is equivalent to a command for the power transmitted through the voltage converter 5.

[0067] The motor ECU 72 is a computer that primarily manages the flow of power from the first power circuit 2 to the drive motor M. The motor ECU 72 operates the power converter 43 based on torque command signals sent from the management ECU 71 to generate torque in the drive motor M corresponding to this command.

[0068] The converter ECU 73 is a computer that primarily manages the flow of power through the voltage converter 5. The converter ECU 73 operates the voltage converter 5 according to power flow command signals sent from the management ECU 71, so that the power flow corresponding to the command passes through the voltage converter 5. More specifically, based on the power flow command, the converter ECU 73 calculates the target current of the signal voltage converter 5 as a target for the current flow, and operates the voltage converter 5 according to a known feedback control algorithm so that the current flow detected by the current sensor 33 (hereinafter also referred to as the "actual current flow") reaches the target current.

[0069] Figure 4 A flowchart illustrating the specific procedures of the power management process is provided. This power management process is repeatedly executed in the management ECU71 at a predetermined cycle.

[0070] First, in S1, the management ECU 71 calculates the required auxiliary power Paux as the power demanded in the vehicle auxiliary equipment 42 and proceeds to S2. The management ECU 71 calculates the required auxiliary power Paux based on information related to the operating status of various electrical loads sent from the vehicle auxiliary equipment 42.

[0071] Next, in S2, the management ECU 71 calculates the required drive power Pmot_d as the power demanded in the drive motor M, and then proceeds to S3. The management ECU 71 calculates the required drive power Pmot_d based on the driver's input to pedals such as the accelerator or brake pedal (see reference). Figure 1 The system calculates the required driving torque by measuring the amount of input from the pedal (P) and converts this required driving torque into electrical power, thereby calculating the required driving power Pmot_d. Therefore, in this embodiment, the required power acquisition component consists of the pedal type P and the management ECU 71.

[0072] Next, in S3, the management ECU71 calculates the total demand power Ptotal by adding the demand auxiliary power Paux and the demand drive power Pmot_d, and then proceeds to S4.

[0073] Next, in S4, the management ECU71 calculates the target power Pcnv_cmd in the voltage converter 5, which corresponds to the power supplied to the target (i.e., the input / output power of the second battery B2), and proceeds to S5. The specific procedure for calculating this target power Pcnv_cmd will be described below. Figure 5 Please provide an explanation.

[0074] Next, in S5, the management ECU71 obtains the first output limit P1_lim, which is equivalent to the upper limit of the power that can be output from the first battery B1, and proceeds to S6.

[0075] Next, in S6, the management ECU 71 determines whether the power obtained by subtracting the target power through voltage Pcnv_cmd from the total power demand Ptotal is below the first output limit P1_lim. Here, the power obtained by subtracting the target power through voltage Pcnv_cmd from the total power demand Ptotal corresponds to the power demand for the first battery B1. Therefore, the determination in S6 is equivalent to determining whether the output power of the first battery B1 can meet the driver's needs without exceeding the first output limit P1_lim. If the determination result of S6 is yes (YES), the management ECU 71 proceeds to S7; if it is no (NO), it proceeds to S8.

[0076] In S7, the management ECU 71 calculates the target drive power Pmot_cmd and proceeds to S9. The target drive power Pmot_cmd corresponds to the target power supplied from the first power circuit 2 to the drive motor M via the power converter 43. As described above, if the determination result in S6 is yes, the output power of the first battery B1 can meet the driver's needs without exceeding the first output limit P1_lim. Therefore, the management ECU 71 uses the required drive power Pmot_d calculated in S2 as the target drive power Pmot_cmd.

[0077] In S8, the management ECU 71 calculates the target drive power Pmot_cmd and proceeds to S9. As described above, if the determination result in S6 is negative, to meet the driver's needs, the output power of the first battery B1 will exceed the first output limit P1_lim. Therefore, the management ECU 71 calculates the target drive power Pmot_cmd in a way that the output power of the first battery B1 does not exceed the first output limit P1_lim. More specifically, the management ECU 71 calculates the target drive power Pmot_cmd, for example, by subtracting the required auxiliary power Paux from the sum of the first output limit P1_lim and the target drive power Pcnv_cmd. Thus, the output power of the first battery B1 is the first output limit P1_lim, and does not exceed this first output limit P1_lim.

[0078] Next, in S9, the management ECU 71 generates a power command signal corresponding to the target power Pcnv_cmd calculated in S4 and sends it to the converter ECU 73, proceeding to S10. The converter ECU 73 operates the voltage converter 5 based on this power command signal. Thus, the power corresponding to the target power Pcnv_cmd is output from the second battery B2 to the first power circuit 2.

[0079] Next, in S10, the management ECU 71 generates a torque command signal based on the target drive power Pmot_cmd and sends it to the motor ECU 72, ending the power management process. More specifically, the management ECU 71 calculates the target drive torque by converting the target drive power Pmot_cmd into torque and generates a torque command signal corresponding to this target drive torque. The motor ECU 72 operates the power converter 43 based on this torque command signal. Thus, the power corresponding to the target drive power Pmot_cmd is output from the first power circuit 2 to the drive motor M. In this way, in the management ECU 71, by generating the torque command signal based on the target drive power Pmot_cmd calculated through processing in S7 or S8, the power output from the first battery B1 will not exceed the first output limit P1_lim.

[0080] Figure 5 This is a flowchart illustrating the procedure in the voltage converter 5, which calculates the target power Pcnv_cmd for the power through the management ECU71.

[0081] First, in S21, the management ECU 71 determines whether the value of the output limit requirement flag for the second battery B2 is "1". This output limit requirement flag for the second battery B2 is a flag indicating a state where the output power requirement of the second battery B2 is limited, and it is updated through a process (not shown) of the second battery ECU 75. If a regular battery discharges at excessively high temperatures, it may accelerate degradation. Therefore, if the temperature of the second battery B2 is higher than the degradation suppression temperature, the second battery ECU 75 should limit the output of the second battery B2 and set the value of the output limit requirement flag to "1" to prevent degradation. Conversely, if the temperature of the second battery B2 is lower than the degradation suppression temperature, the second battery ECU 75 should release the output limit of the second battery B2 and reset the value of the output limit requirement flag to "0". If the determination result in S21 is negative, the process proceeds to S22; if it is positive, the process proceeds to S25.

[0082] In step S22, the management ECU 71 determines whether the second contactors 32p and 32n are open, i.e., whether the second battery B2 is blocked from the second power lines 31p and 31n. If the determination result of S22 is yes, the management ECU 71 proceeds to S23, whereby the second contactors 32p and 32n should be connected. After sending a command to the second battery ECU 75 to connect the second contactors 32p and 32n, the process proceeds to S24. Conversely, if the determination result of S22 is no, the management ECU 71 keeps the second contactors 32p and 32n connected and proceeds to S24.

[0083] In S24, the management ECU71 calculates the target power Pcnv_cmd based on the prescribed algorithm and then returns to... Figure 4 S5. More specifically, the management ECU 71 calculates the target power Pcnv_cmd based on information related to parameters indicating the internal state of the first battery B1 sent from the first battery ECU 74, information related to parameters indicating the internal state of the second battery B2 sent from the second battery ECU 75, and the demand-driven power Pmot_d, etc. That is, when the management ECU 71 requires power output from the second battery B2, for example, during acceleration and the second battery B2 has a sufficient charge rate, it sets the target power Pcnv_cmd to a positive predetermined value and outputs power from the second battery B2. On the other hand, when the management ECU 71 requires power output from the second battery B2, for example, during acceleration and the second battery B2 has a sufficient charge rate, it sets the target power Pcnv_cmd to a negative predetermined value and supplies a portion of the power from the first power circuit 2 to the second battery B2.

[0084] In S25, the management ECU 71 determines whether the second contactors 32p and 32n are disconnected. If the determination result in S25 is negative, the management ECU 71 performs a blocking determination process (refer to S26), that is, disconnects the second contactors 32p and 32n at an appropriate time corresponding to the state of the first battery B1 or the second battery B2, and then returns to the previous state. Figure 4 S5. Additionally, if the determination result of S25 is yes, the management ECU 71 performs a reset determination process (refer to S27), that is, at the appropriate time corresponding to the state of the first battery B1 or the second battery B2, etc., the second contactor 32p, 32n is activated, and then returns to... Figure 4 S5.

[0085] Figure 6 A flowchart illustrating the specific procedure for blocking determination and processing is provided.

[0086] First, in S31, the management ECU 71 calculates the first closed-circuit voltage lower limit CCVmin1, which corresponds to the closed-circuit voltage lower limit of the first battery B1, based on various parameters representing the internal state of the first battery B1 sent from the first battery ECU 74, and then proceeds to S32. More specifically, the management ECU 71 follows the procedure described below. Figure 7 The procedure described calculates the lower limit of the first closed-circuit voltage, CCVmin1.

[0087] Next, in S32, the management ECU 71 calculates the second closed-circuit voltage lower limit CCVmin2, which corresponds to the lower limit of the closed-circuit voltage of the second battery B2, based on various parameters representing the internal state of the second battery B2 sent from the second battery ECU 75, and proceeds to S33. More specifically, the management ECU 71 follows the procedure described below. Figure 8The procedure described calculates the lower limit of the second closed-circuit voltage, CCVmin2.

[0088] Next, in S33, the management ECU71 determines whether the voltage difference obtained by subtracting the second closed-circuit voltage lower limit CCVmin2 from the first closed-circuit voltage lower limit CCVmin1 is above the first voltage difference threshold A, which is positive.

[0089] If the decision result in S33 is yes, the management ECU 71 determines that the first closed-circuit voltage lower limit CCVmin1 is sufficiently higher than the second closed-circuit voltage lower limit CCVmin2. Even without disconnecting the second contactors 32p and 32n, no unexpected current will flow from the second power circuit 3 to the first power circuit 2, and then proceeds to S34. In S34, the management ECU 71 calculates the target power supply Pcnv_cmd within the output limit required for the second battery B2 and returns to... Figure 4 S5.

[0090] If the decision result of the management ECU71 in S33 is negative, that is, if the voltage difference between the first closed-circuit voltage lower limit CCVmin1 and the second closed-circuit voltage lower limit CCVmin2 does not reach the first voltage difference threshold A, it is determined that if the second contactors 32p and 32n are not disconnected, there is a possibility that an unexpected current will flow from the second power circuit 3 to the first power circuit 2, and the process proceeds to S35.

[0091] In S35, before disconnecting the second contactors 32p and 32n, the management ECU 71 should reduce the power of the voltage converter 5 to near 0, set the target power Pcnv_cmd to 0, and proceed to step S36.

[0092] In step S36, the management ECU 71 calculates the actual power Pwp of the voltage converter 5, which corresponds to the input / output power of the second battery B2, based on the detection signal from the current sensor 33, and proceeds to step S37. In step S37, the management ECU 71 determines whether the absolute value of the actual power Pwp is below a power threshold B that is set to be slightly greater than 0.

[0093] If the decision result of management ECU71 in S36 is negative, that is, even though the target power Pcnv_cmd is set to 0 in S35, but the absolute value of the actual power Pwp has not decreased below the power threshold B, it should wait for the absolute value of the actual power Pwp to decrease below the power threshold B, maintain the second contactor 32p and 32n connected, and return to the previous state. Figure 4 S5.

[0094] If the determination result of management ECU 71 in S36 is yes, that is, if the absolute value of the actual power Pwp has decreased below the power threshold B, then proceed to S38. In S38, management ECU 71 should disconnect the second contactors 32p and 32n. After sending the command to disconnect the second contactors 32p and 32n to the second battery ECU 75, return to... Figure 4 S5.

[0095] Figure 7 The flowchart shows the procedure for calculating the first closed-circuit voltage lower limit CCVmin1 of the first battery B1.

[0096] After the management ECU71 obtains the internal resistance R1 of the first battery B1 (refer to S41), the closed-circuit voltage CCV1 of the first battery B1 (refer to S42), and the current I1 of the first battery B1 (refer to S43) from the first battery ECU74, it calculates the static voltage OCV1 of the first battery B1 based on the following formula (1) (refer to S44).

[0097] [Formula 1]

[0098] OCV1=CCV1-I1·R1 (1)

[0099] Next, the management ECU71 obtains the first output upper limit P1_lim of the first battery B1 (refer to S45) and the lowest value of the multiple cell voltages of the first battery B1, i.e., the lowest cell voltage VCmin1 (refer to S46), from the first battery ECU74, and then calculates the first high output voltage CCVlim1 of the first battery B1 based on the following formula (2) (refer to S47). In addition, the first high output voltage CCVlim1 is equivalent to the closed-circuit voltage of the first battery B1 when the output of the first battery B1 is used as the first output upper limit P1_lim.

[0100] [Formula 2]

[0101]

[0102] Next, as shown in equation (3), the management ECU71 takes the smaller of the voltage obtained by multiplying the minimum cell voltage VCmin1 by the number of cells NC1 of the first battery B1 and the voltage CCVlim1 at the first high output as the first closed-circuit voltage lower limit CCVmin1. Figure 7 The processing shown is now complete (see S48).

[0103] [Formula 3]

[0104] CCVmin1=min(VCmin1.NC1.CCVIimI)(3)

[0105] Figure 8The flowchart shows the procedure for calculating the second closed-circuit voltage lower limit CCVmin2 of the second battery B2.

[0106] After the management ECU71 obtains the internal resistance R2 of the second battery B2 (refer to S51), the closed-circuit voltage CCV2 of the second battery B2 (refer to S52), and the current I2 of the second battery B2 (refer to S53) from the second battery ECU75, it calculates the static voltage OCV2 of the second battery B2 based on the following formula (4) (refer to S54).

[0107] [Formula 4]

[0108] OCV2=CCV2-I2·R2 (4)

[0109] Next, the management ECU 71 obtains the second output upper limit P2_lim of the second battery B2 (refer to S55) and the lowest value of the multiple cell voltages of the second battery B2, i.e., the lowest cell voltage VCmin2 (refer to S56), from the second battery ECU 75, and then calculates the second highest output voltage CCVlim2 of the second battery B2 based on the following formula (5) (refer to S57). In addition, the second highest output voltage CCVlim2 is equivalent to the closed-circuit voltage of the second battery B2 when the output of the second battery B2 is used as the second output upper limit P2_lim.

[0110] [Formula 5]

[0111]

[0112] Next, as shown in equation (6), the management ECU71 takes the smaller of the voltage obtained by multiplying the minimum cell voltage VCmin2 by the number of cells NC2 of the second battery B2 and the voltage CCVlim2 at the second high output as the lower limit of the second closed-circuit voltage CCVmin2. Figure 8 The processing shown is now complete (see S58).

[0113] [Formula 6]

[0114] CCVmin2=min(VCmin2·NC2,CCVlim2) (6)

[0115] Figure 9 The flowchart illustrates the specific procedure for the reset determination process.

[0116] First, in S61, ECU71 is managed according to reference... Figure 7 The procedure described above calculates the first closed-circuit voltage lower limit CCVmin1 of the first battery B1 and proceeds to S61. Then, in S62, the management ECU 71 follows the reference... Figure 8The procedure described calculates the second closed-circuit voltage lower limit CCVmin2 of the second battery B2 and then proceeds to S63.

[0117] Next, in S63, the management ECU71 determines whether the voltage difference obtained by subtracting the second closed-circuit voltage lower limit CCVmin2 from the first closed-circuit voltage lower limit CCVmin1 is above the positive second voltage difference threshold C. In addition, in order to prevent the second contactors 32p and 32n from oscillating, the second voltage difference threshold C is set to be slightly greater than the first voltage difference threshold A.

[0118] If the determination result of the management ECU 71 in S63 is negative, that is, if the voltage difference between the first closed-circuit voltage lower limit CCVmin1 and the second closed-circuit voltage lower limit CCVmin2 does not reach the second voltage difference threshold C, it is determined that: if the second contactors 32p and 32n are connected, there is a possibility that an unexpected current will flow from the second power circuit 3 to the first power circuit 2, and the process proceeds to S64. In S64, the management ECU 71 keeps the second contactors 32p and 32n open and sets the target power supply Pcnv_cmd to 0, then returns to... Figure 4 S5.

[0119] If the determination result in S63 is yes, the management ECU 71 determines that the first closed-circuit voltage lower limit CCVmin1 is sufficiently higher than the second closed-circuit voltage lower limit CCVmin2. Even if the second contactors 32p and 32n are closed, no unexpected current will flow from the second power circuit 3 to the first power circuit 2, and then proceeds to S65. In S65, the management ECU 71 should close the second contactors 32p and 32n. After sending the instruction to the second battery ECU 75 to close the second contactors 32p and 32n, it proceeds to S66. In S66, the management ECU 71 calculates the target power Pcnv_cmd within the output limit required by the second battery B2 and returns to... Figure 4 S5.

[0120] As mentioned above, in Figures 5-9 In the process shown, the management ECU 71 is in operation during the period when the second battery B2 is subject to an output limitation requirement (refer to...). Figure 5 (S21) When the voltage difference between the first closed-circuit voltage lower limit CCVmin1 and the second closed-circuit voltage lower limit CCVmin2 does not reach the first voltage difference threshold A (refer to S21) Figure 6 (S33), the operating voltage converter 5 makes the absolute value of the actual power Pwp below the power threshold B (refer to S33). Figure 6 (S35~S37) When the absolute value of the actual power Pwp reaches below the power threshold B, the second battery B2 is disconnected from the second power lines 31p and 31n (refer to S35~S37). Figure 6(S38). Additionally, after the management ECU 71 disconnects the second battery B2 from the second power lines 31p and 31n via the above procedure, and the output limit of the second battery B2 is released (refer to...). Figure 5 S21), or when the voltage difference between the first closed-circuit voltage lower limit CCVmin1 and the second closed-circuit voltage lower limit CCVmin2 reaches or exceeds the second voltage difference threshold C (refer to S21). Figure 9 (S63) Connect the second battery B2 to the second power lines 31p and 31n (refer to S63) Figure 5 S23 and Figure 9 (S64).

[0121] The power supply system 1 according to this embodiment has the following effects.

[0122] (1) In power supply system 1, a first power circuit 2 and a second power circuit 3 are connected by a voltage converter 5, and the first power circuit 2 is connected to a drive motor M by a power converter 43. The first power circuit 2 has a first battery B1, and the second power circuit 3 has a second battery B2. The operating voltage range of the second battery B2 for closed-circuit voltage overlaps with that of the first battery B1, and its static voltage is lower than that of the first battery B1. The electronic control unit group 7 operates the power converter 43, the voltage converter 5, and the second power circuit 3 based on the required drive power Pmot_d of the drive motor M. In this power supply system 1, for example, when the required drive power Pmot_d increases according to acceleration requirements, the electronic control unit group 7 operates the power converter 43 or the voltage converter 5 and combines the power output from the first battery B1 with the power output from the second battery B2 to supply the output power corresponding to the required drive power Pmot_d from the power converter 43 to the drive motor M. Here, if it is desired to suppress (including prohibit) the discharge from the second battery B2 for some reason, the electronic control unit group 7 operates the voltage converter 5 or the power converter 43 to provide all or most of the required driving power Pmot_d by means of the power output from the first battery B1. However, when the current flowing in the first battery B1 increases, there is a situation where the closed-circuit voltage of the first battery B1 becomes lower than the static voltage of the second battery B2, resulting in the unintended output of power from the second battery B2. In this regard, in the present invention, when the second battery B2 is subject to an output restriction requirement, if the voltage difference between the first closed-circuit voltage lower limit CCVmin1 of the first battery B1 and the second closed-circuit voltage lower limit CCVmin2 of the second battery B2 does not reach the first voltage difference threshold A, the second battery B2 is blocked from the second power lines 31p and 31n of the second power circuit 3. Therefore, according to power system 1, the second battery B2 can be reliably disconnected from the second power lines 31p, 31n, and even the first power circuit 2, thus reliably suppressing unintended discharge from the second battery B2. Furthermore, according to power system 1, unlike the power system described in Japanese Patent Application Publication No. 2020-162251, it is not necessary to suppress the output power of the first battery B1. Therefore, not only can unintended discharge from the second battery B2 be suppressed, but the required drive power Pmot_d can also be continuously supplied to the drive motor M.

[0123] (2) In the power supply system 1, when the second battery B2 is subject to an output limitation requirement, if the voltage difference does not reach the first voltage difference threshold A, the electronic control unit group 7 operates the voltage converter 5 to make the absolute value of the actual power Pwp passing through the voltage converter 5 reach below the power threshold B. When the actual power Pwp reaches below the power threshold B, the second battery B2 is disconnected from the second power lines 31p and 31n. Thus, by disconnecting the second battery B2 from the second power lines 31p and 31n while a discharge current or a charging current is flowing in the second battery B2, the impact on vehicle behavior can be suppressed.

[0124] (3) In the power supply system 1, the electronic control unit group 7 connects the second battery B2 to the second power lines 31p and 31n after disconnecting the second battery B2 from the second power lines 31p and 31n, when the output limit of the second battery B2 is released, or when the voltage difference reaches or exceeds the second voltage difference threshold C. This allows for rapid power supply from the second battery B2 to the first power circuit 2 when needed.

[0125] (4) In the power system 1, the management ECU 71 calculates the lower limits of the closed-circuit voltage of the first battery B1 and the second battery B2 as the first closed-circuit voltage lower limit CCVmin1 and the second closed-circuit voltage lower limit CCVmin2. This allows the second battery B2 to be disconnected from the second power lines 31p and 31n at the appropriate time, so as to effectively suppress the unexpected discharge from the second battery B2.

[0126] The above description illustrates one embodiment of the present invention, but the invention is not limited thereto. Appropriate modifications to the details can be made within the scope of the invention's intent.

[0127] Figure Labels

[0128] V: Vehicle

[0129] M: Drive motor (rotary electric motor)

[0130] P: Pedal type (electricity demand acquisition component)

[0131] 1: Power System

[0132] 2: First power circuit

[0133] 21p, 21n: First electric line

[0134] 22p, 22n: First contactor

[0135] B1: First battery (first energy storage device)

[0136] 3: Second power circuit (Second power circuit)

[0137] 31p, 31n: Second power line

[0138] 32p, 32n: Second contactor

[0139] 33: Current sensor

[0140] B2: Second battery (second energy storage device)

[0141] 43: Power Converter

[0142] 5: Voltage converter

[0143] 7: Electronic control unit group (power control component, first voltage acquisition component, second voltage acquisition component)

[0144] 71: Managing the ECU (Electronic Control Unit for Demand Power Acquisition)

[0145] 72: Motor ECU

[0146] 73: Converter ECU

[0147] 74: Battery 1 ECU

[0148] 75: Second Battery ECU

[0149] 81: First battery sensor unit (first voltage acquisition component)

[0150] 82: Second battery sensor unit (second voltage acquisition component)

Claims

1. A power supply system, comprising: The first power circuit has a first energy storage device and a first power line to which the first energy storage device is connected; The second power circuit has a second energy storage device, a second power line to which the second energy storage device is connected, and a second contactor disposed on the second power line. The operating voltage range of the second energy storage device for closed-circuit voltage is the same as that of the first energy storage device, and the static voltage is lower than that of the first energy storage device. A voltage converter that converts voltage between the first power line and the second power line; A power converter that converts power between the first power line and the rotating motor; The first voltage acquisition component acquires the first voltage of the first energy storage device; The second voltage acquisition component acquires the second voltage of the second energy storage device; A power demand acquisition component that acquires the power demand of the rotating motor; as well as An electrical control component that operates the power converter, the voltage converter, and the second electrical circuit based on the required power. The power supply system is characterized by: When the second energy storage device is subject to an output limitation requirement, and the voltage difference between the first voltage and the second voltage does not reach a first voltage difference threshold, the power control component disconnects the second energy storage device from the second power line by disconnecting the second contactor.

2. The power supply system according to claim 1, characterized in that: When the second energy storage device is subject to an output limitation requirement, and the voltage difference does not reach the first voltage difference threshold, the power control component operates the voltage converter to bring the absolute value of the input and output power of the second energy storage device below the power threshold. When the input and output power of the second energy storage device reaches below the power threshold, the second energy storage device is disconnected from the second power line.

3. The power supply system according to claim 1 or 2, characterized in that: When the power control component disconnects the second energy storage device from the second power line, and the output limitation of the second energy storage device is released, or when the voltage difference reaches or exceeds the second voltage difference threshold, the second energy storage device is connected to the second power line.

4. The power supply system according to claim 1 or 2, characterized in that: The first and second voltage acquisition components respectively acquire the lower limits of the closed-circuit voltage of the first and second energy storage devices, and use them as the first and second voltages.

5. The power supply system according to claim 3, characterized in that: The first and second voltage acquisition components respectively acquire the lower limits of the closed-circuit voltage of the first and second energy storage devices, and use them as the first and second voltages.

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