Charging control device
The charging control device estimates and limits the charging current to prevent lithium deposition in lithium-ion batteries by deriving protective charging currents and limit values, addressing the issue of excess current flow during load current fluctuations.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-12-26
- Publication Date
- 2026-06-02
Smart Images
Figure 0007868608000001 
Figure 0007868608000002
Abstract
Description
Technical Field
[0001] The present disclosure relates to a charging control device for controlling the charging of a lithium-ion battery.
Background Art
[0002] Patent Document 1 discloses a charge-discharge control device capable of improving the controllability of charge-discharge operations while sufficiently protecting the performance of a lithium-ion battery. In this charge-discharge control device, it is described that feedforward control for performing stable control using the input-output map of the battery and feedback control for performing limitation based on limit values when feedforward control is difficult are used in combination.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the charge-discharge control device described in Patent Document 1, in order not to cause lithium precipitation in the lithium-ion battery, feedback control is performed so as not to exceed the upper limit current obtained from the charging current, and the charge-discharge of the lithium-ion battery is controlled.
[0005] However, in a system in which charging from a generator to a lithium-ion battery and power supply to a load can be executed in parallel, the consumption current on the load side may significantly decrease (such as the operation of the load stopping) during charging of the lithium-ion battery. In this case, the current portion (surplus current) that is no longer consumed by the load flows into the lithium-ion battery. If the surplus current is large, the feedback control may not be in time, and there is a possibility of exceeding the upper limit current that does not cause lithium precipitation.
[0006] This disclosure has been made in view of the above-mentioned problems, and aims to provide a charging control device that can control the charging of a lithium-ion battery without exceeding the upper limit current that does not cause lithium deposition, even when an increase in charging current occurs due to a decrease in current consumption on the load side while the lithium-ion battery is being charged. [Means for solving the problem]
[0007] To solve the above problems, one aspect of the disclosed technology is a charge control device for controlling the charging of a lithium-ion battery, comprising: a first processing unit that estimates the inflow current that flows into the lithium-ion battery when the current flowing to the load is gone; a second processing unit that derives a protective charging current, which is the maximum value of the charging current that does not cause lithium deposition in the lithium-ion battery; a third processing unit that calculates a charging limit current, which is the upper limit of the current used to charge the lithium-ion battery, based on the protective charging current and the inflow current; and a fourth processing unit that controls the charging of the lithium-ion battery based on a limiting power calculated from the charging limit current and the voltage of the lithium-ion battery. [Effects of the Invention]
[0008] According to the charging control device of the present disclosure, even if the current consumption of the load stops while the lithium-ion battery is being charged and the charging current of the lithium-ion battery increases, the charging of the lithium-ion battery can be controlled without exceeding the upper limit current that does not cause lithium deposition. [Brief explanation of the drawing]
[0009] [Figure 1] Functional block diagram of a charging control device and its peripheral parts according to one embodiment of the present disclosure. [Figure 2] Flowchart of the charging control process for lithium-ion batteries performed by the charging control device. [Modes for carrying out the invention]
[0010] The charging control device of this disclosure, when charging a lithium-ion battery and supplying power to a load using a power source, anticipates a scenario in which the current flowing into the lithium-ion battery increases due to the cessation of current consumption by the load. It pre-determines the maximum charging current for such a scenario and controls the charging of the lithium-ion battery. This makes it possible to avoid the occurrence of lithium deposition in the lithium-ion battery. The embodiments of this disclosure will be described in detail below with reference to the drawings.
[0011] <Embodiment> [composition] Figure 1 is a functional block diagram of a charging control device 100 and its surrounding components according to one embodiment of the present disclosure. Figure 1 shows an example in which a lithium-ion battery 41 mounted on a vehicle is controlled by the charging control device 100. The functional block illustrated in Figure 1 includes an engine 10, a motor generator (MG) 20, an electronic load 30, a Li battery module 40, an auxiliary battery 50, and a charging control device 100.
[0012] Engine 10 is an internal combustion engine that serves as the power source for the vehicle. This engine 10 is started by a motor generator (MG) 20 or the like.
[0013] The motor generator (MG) 20 is an electric generator that combines an electric function for starting the engine 10 and a power generation function that generates electricity driven by the power or regenerative operation of the engine 10. This motor generator (MG) 20 performs its electric function using electricity supplied from the Li battery module 40.
[0014] The electronic load 30 consists of various power-consuming devices and systems mounted on the vehicle. This electronic load 30 is configured to operate using at least one of the following power sources: power generated by the motor generator (MG) 20, power supplied from the Li battery module 40 via the charge control device 100, and power stored in the auxiliary battery 50. Examples of the electronic load 30 include auxiliary equipment other than those used to drive the vehicle (such as air conditioning equipment and lighting equipment).
[0015] The Li-battery module 40 is a unit that includes a rechargeable secondary battery. This Li-battery module 40 includes a lithium-ion battery 41 and a sensor 42. The lithium-ion battery 41 is a rechargeable secondary battery and, for example, takes the form of a stack configuration in which multiple lithium-ion battery cells are connected in series. The sensor 42 is configured to detect the state of the lithium-ion battery 41. Various sensors are used in this sensor 42, such as a voltage sensor to monitor the voltage of the lithium-ion battery 41, a current sensor to monitor the current flowing into and out of the lithium-ion battery 41, and a temperature sensor to monitor the temperature of the lithium-ion battery 41.
[0016] This Li-cell battery module 40 stores the power output by the motor generator (MG) 20 and outputs the power it has stored to the charge control device 100. An example of this Li-cell battery module 40 is a battery module with a rated voltage of 48V used in so-called mild hybrid systems.
[0017] The auxiliary battery 50 is a rechargeable secondary battery, such as a lead-acid battery or a lithium-ion battery. This auxiliary battery 50 stores power output from the charge control device 100 and supplies the power it has stored to the electronic load 30. An example of this auxiliary battery 50 is a battery with a rated voltage of 12V.
[0018] The charging control device 100 is a configuration for controlling the charging of the lithium-ion battery 41 of the Li battery module 40. This charging control device 100 includes a DDC circuit 101 and a control processing unit 102.
[0019] The DDC circuit 101 is a step-down DCDC converter that converts the input power into a predetermined voltage and outputs it. This DDC circuit 101 is arranged between the motor generator (MG) 20 and the Li battery module 40 and the electronic load 30 and the accessory battery 50, and steps down the 48V system power input from the motor generator (MG) 20 and the Li battery module 40 to 12V system power and outputs it to the electronic load 30 and the accessory battery 50. The operation of the DDC circuit 101 is controlled by the control processing unit 102.
[0020] The control processing unit 102 acquires the state (voltage, current, temperature) of the lithium-ion battery 41 from the sensor 42 of the Li battery module 40. Also, the control processing unit 102 acquires the value of the current flowing from the DDC circuit 101 to the electronic load 30 (and the accessory battery 50) (hereinafter referred to as "12V current"). This 12V current can be acquired using a current sensor (not shown) provided at the output stage of the DDC circuit 101. Then, the control processing unit 102 controls the charging of the lithium-ion battery 41 based on the state of the lithium-ion battery 41 and the 12V current. The charging control of this lithium-ion battery 41 will be described later.
[0021] Note that part or all of the above-described charging control device 100 can typically be constituted by an electronic control device (ECU: Electronic Control Unit) including a processor such as a microcomputer, a memory, and an input / output interface. This electronic control device can realize part or all of the above-described functions by the processor reading and executing a program stored in the memory.
[0022] [Control] Next, referring further to FIG. 2, the control performed by the charging control device 100 according to the present embodiment will be described. FIG. 2 is a flowchart for explaining the processing procedure of charging control of the lithium-ion battery 41 executed by the control processing unit 102 of the charging control device 100.
[0023] The charging control of the lithium-ion battery 41 illustrated in FIG. 2 is started, for example, when the vehicle system is started, and is repeatedly performed at a predetermined timing (such as a fixed cycle) until the vehicle system stops.
[0024] (Step S201) Based on the 12V current output from the DDC circuit 101, the control processing unit 102 of the charging control device 100 estimates the inflow current to the lithium-ion battery 41 that is expected to increase when the electronic load 30 stops (first process). This inflow current (hereinafter referred to as "estimated inflow current") can be estimated by the following equation [1] using a current conversion coefficient and a DDC efficiency coefficient. Estimated inflow current = 12V current × current conversion coefficient × DDC efficiency coefficient …[1]
[0025] Here, the current conversion coefficient is a coefficient (48V / 12V) for converting the value of the 12V current into the value of the current flowing from the motor generator (MG) 20 to the DDC circuit 101 (hereinafter referred to as "48V current"). The DDC efficiency coefficient is a coefficient corresponding to the conversion efficiency in the DDC circuit 101. When the DDC circuit 101 is a system that does not perform a step-down operation, the current conversion coefficient may be omitted.
[0026] When the inflow current to the lithium-ion battery 41 is estimated by the control processing unit 102, the process proceeds to step S202.
[0027] (Step S202) The control processing unit 102 of the charging control device 100 derives the lithium-ion battery 41 lithium deposition protection charging current (second process). This lithium deposition protection charging current is the maximum charging current that can charge the lithium-ion battery 41 without causing lithium deposition. The lithium deposition protection charging current is derived based on the voltage, current, and temperature of the lithium-ion battery 41 at the time of derivation, as well as the amount of stored energy (SOC: State of Charge) calculated from this information. Various well-known methods can be used to derive the lithium deposition protection charging current.
[0028] Once the control processing unit 102 derives the Li deposition protection charging current for the lithium-ion battery 41, the process proceeds to step S203.
[0029] (Step S203) The control processing unit 102 of the charge control device 100 derives the maximum charge current for the lithium-ion battery 41 (third process). This maximum charge current is the upper limit of the charge current that can charge the lithium-ion battery 41 without causing lithium deposition, taking into account the increase in current directed to the lithium-ion battery 41 when the operation of the electronic load 30 stops and current consumption ceases. The maximum charge current is derived by the following equation [2] based on the estimated inflow current estimated in step S201 and the Li deposition protection charge current derived in step S202. Charging upper limit current = Li deposition protection charging current - estimated inflow current …[2]
[0030] Once the control processing unit 102 derives the maximum charging current for the lithium-ion battery 41, the process proceeds to step S204.
[0031] (Step S204) The control processing unit 102 of the charging control device 100 derives the limiting power of the lithium-ion battery 41 (fourth process). This limiting power represents the charging power that allows the lithium-ion battery 41 to be charged without causing lithium deposition, taking into account the shutdown of the electronic load 30 and other factors. The limiting power is derived from the upper limit charging current derived in step S203 and the voltage of the lithium-ion battery 41 (battery voltage) by the following equation [3]. Power limit = maximum charging current × battery voltage …[3]
[0032] Once the control processing unit 102 derives the limiting power of the lithium-ion battery 41, the process proceeds to step S205.
[0033] (Step S205) The control processing unit 102 of the charging control device 100 controls the charging of the lithium-ion battery 41 based on the limited power derived in step S204 (fourth process). Once the control processing unit 102 controls the charging of the lithium-ion battery 41 based on the limited power, the process proceeds to step S201.
[0034] <Effects and Actions> As described above, according to the charging control device 100 of one embodiment of the present disclosure, the charging of the lithium-ion battery 41 is controlled (feedforward control) using a preset charging power within a range in which lithium deposition does not occur in the lithium-ion battery 41, based on a charging current that assumes the current consumed by the electronic load 30 flows into the lithium-ion battery 41.
[0035] This control allows the lithium-ion battery 41 to continue charging without causing lithium deposition, even if, for example, the current consumption of the electronic load 30 suddenly increases due to the current consumption of the electronic load 30 being eliminated or significantly reduced while the motor generator (MG) 20 is generating power to charge the lithium-ion battery 41 and supply power to the electronic load 30.
[0036] Although one embodiment of the present disclosure has been described above, the present disclosure can be understood not only as a charging control device, but also as a method executed by a charging control device equipped with a processor, memory, etc., a program for executing this method, a computer-readable non-temporary storage medium storing the program, and a vehicle equipped with the charging control device. [Industrial applicability]
[0037] The charging control device of this disclosure can be used when it is desired to control the charging of a lithium-ion battery without causing lithium deposition. [Explanation of symbols]
[0038] 10 Engines 20 Motor Generator (MG) 30 electronic load 40 Li-cell battery module 41 Lithium-ion battery 42 sensors 50 Auxiliary Battery 100 Charging control device 101 DDC circuit 102 Control Processing Unit
Claims
1. A charge control device for controlling the charging of a lithium-ion battery, A first processing unit that estimates the incoming current that flows into the lithium-ion battery when the current flowing through the load is cut off, A second processing unit that derives a protective charging current, which is the maximum value of the charging current that does not cause lithium deposition in the lithium-ion battery, A third processing unit calculates a charging limit current, which is the upper limit of the current used to charge the lithium-ion battery, based on the protective charging current and the inflow current. A charging control device comprising: a fourth processing unit that controls the charging of the lithium-ion battery based on a limiting power calculated from the charging limit current and the voltage of the lithium-ion battery.
2. The charging control device according to claim 1, wherein the second processing unit derives the protective charging current based on at least one of the voltage, current, temperature, and amount of charge of the lithium-ion battery.
3. The lithium-ion battery and the load are connected by a DC-DC converter. The charging control device according to claim 1 or 2, wherein the first processing unit estimates the incoming current based on the current flowing through the load and the conversion efficiency of the DC-DC converter.
4. The DCDC converter is of the step-down type, The charging control device according to claim 3, wherein the first processing unit further estimates the incoming current based on a current conversion coefficient.