Charging control method and charging control device

Abstract

A charge control method according to one embodiment of the present invention controls the charging of an in-vehicle battery that comprises a lithium ion battery. According to this charge control method, a long-term chargeable power that is capable of charging a battery for a long period of time is calculated; a short-term chargeable power that is higher than the long-term chargeable power and is capable of charging the battery for a short period of time is calculated; a continuous chargeable power that is capable of continuously charging the battery is calculated on the basis of the long-term chargeable power and the short-term chargeable power; and the upper limit of the charging power for a battery 1 is set to the continuous chargeable power.

Description

[Technical Field]

[0001] The present invention relates to a charging control method and a charging control device for a battery including a lithium ion battery. [Background technology]

[0002] A method for controlling the charging and discharging of a secondary battery is known (see, for example, Patent Document 1), in which the charging power upper limit value Pin-s and the discharging power upper limit value Pout-s are set to be smaller than those at room temperature when the battery temperature is below a predetermined temperature or above a predetermined temperature, the battery temperature is detected, and the charging power and discharging power are set to be equal to or less than the charging and discharging power upper limit values Pin-s and Pout-s at the detected temperature, thereby controlling the charging of the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-219510 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the charging of a vehicle battery is controlled using the control method of the conventional charging control device, the upper limit of the chargeable power set when the battery temperature is low becomes low, which causes a problem that it is difficult for the battery to absorb the power generated depending on the vehicle's driving situation.

[0005] The problem to be solved by the present invention is to provide a charge control method and a charge control device that can absorb, by a battery, the electric power generated depending on the driving situation of a vehicle. [Means for solving the problem]

[0006] The present invention solves the above problem by calculating the long-term chargeable power, calculating the short-term chargeable power that is greater than the long-term chargeable power, calculating the continuous chargeable power based on the short-term chargeable power and the long-term chargeable power, and limiting the upper limit of the battery's charging power to the continuous chargeable power. [Effects of the Invention]

[0007] According to the present invention, the battery can absorb the electric power generated depending on the driving situation of the vehicle. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a drive system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a graph showing the voltage characteristics (a) and charging power characteristics (b) of the battery. [Figure 3] FIG. 3 is a graph showing the response characteristics of short-term chargeable power, medium-term chargeable power, and long-term chargeable power. [Figure 4] FIG. 4 is a block diagram showing functional blocks of the chargeable power calculation unit. [Figure 5] FIG. 5 is a graph showing the characteristics of short-term / long-term chargeable power, target maintenance power, actual charge power, and continuous chargeable power. [Figure 6] FIG. 6 is a flowchart of the charge control method according to this embodiment. [Figure 7] FIG. 7 is a block diagram showing a drive system according to another embodiment of the present invention. [Figure 8] FIG. 8 is a table for explaining the correlation between battery temperature (cell temperature), SOC, short-term chargeable power, and target maintenance power. [Figure 9] FIG. 9 is a conceptual diagram of a map stored in the upper limit SOC calculation unit. [Figure 10] FIG. 10 is a block diagram showing a control flow of a method for calculating the upper limit SOC by the upper limit SOC calculation unit. [Figure 11]FIG. 11 is a flowchart of a charge control method according to another embodiment of the present invention. [Figure 12] FIG. 12 is a block diagram showing a drive system according to another embodiment of the present invention. [Figure 13] FIG. 13 is a block diagram showing a control flow of a warm-up determination method performed by the warm-up determination unit. [Figure 14] FIG. 14 is a time chart of various parameters related to warm-up determination and the warm-up determination results, where (a) shows the time chart at extremely low temperatures, and (b) shows the time chart at low temperatures. [Figure 15] FIG. 15 is a flowchart of a charge control method according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment An embodiment of a charge control system according to the present invention will now be described with reference to the drawings. Fig. 1 is a block diagram showing a drive system according to the embodiment of the present invention. The drive system is a drive system for a hybrid vehicle and includes a battery 1, an engine 30, a generator 40, a motor / inverter 50, and a charge control device 100. A battery charge / discharge control system according to this embodiment is part of the drive system and controls the discharge power supplied from the battery 1 to the motor 50 and the charge power used to charge the battery 1 with power generated by the generator 40. Note that the charge control method and charge control device according to this embodiment mainly relate to control during charging of the battery 1, and the following description will mainly focus on the charge control of the battery 1.

[0010] Battery 1 is a power source provided in a hybrid vehicle and includes multiple lithium-ion batteries. Lithium-ion batteries are charged and discharged by the movement of lithium ions between positive and negative electrodes. Engine 30, generator 40, and motor 50 constitute a series hybrid drive system, with engine 30 used to drive generator 40, and power generated by generator 40 supplied to battery 1 to charge it. At this time, charge control device 100 controls the rotation speed of generator 40 to control the charging power supplied from generator 40 to battery 1. Motor / inverter 50 includes an inverter that converts the voltage output from battery 1 from direct current to alternating current, and a motor that is driven by the converted alternating current voltage.

[0011] The charge control device 100 is a controller (processor) that controls the charging power of the battery 1 while managing the SOC (State of Charge) of the battery 1. The charge control device 100 has a voltage detection unit 2, a current detection unit 3, a temperature detection unit 4, an SOC estimation unit 5, a short-term chargeable power calculation unit 6, a long-term chargeable power calculation unit 7, a chargeable power calculation unit 8, and a vehicle controller 20.

[0012] The voltage detection unit 2, current detection unit 3, and temperature detection unit 4 are units that detect the internal state of the battery 1, and the voltage sensor, current sensor, and temperature sensor of the battery 1 detect the voltage of each cell included in the battery 1, the current flowing through each cell, and the temperature inside the battery pack.

[0013] The SOC estimation unit 5 estimates the SOC of the battery 1 based on the battery voltage detected by the voltage detection unit 2 and / or the battery current detected by the current detection unit 3. The SOC estimation unit 5 has an SOC-OCV map that associates the OCV and SOC of the battery 1. When the vehicle is started, the SOC estimation unit 5 acquires the no-load voltage (OCV) of the battery 1 from the voltage detection unit 2 and sets an initial SOC by referring to the SOC-OCV map. After the vehicle is started, the SOC estimation unit 5 integrates the current and adds the integrated current value to the initial SOC to estimate the SOC after start-up.

[0014] The short-term chargeable power calculation unit 6 calculates the short-term chargeable power based on the SOC of the battery 1 and the temperature (battery temperature) of the battery 1. The short-term chargeable power is the power that can be used to charge the battery 1 for a short period of time. The short-term chargeable power corresponds to the power generated by an increase in engine speed after the engine 30 is started, or the power that can absorb regenerative charging power while the vehicle is traveling (particularly at high speed). The time period that determines the short-term chargeable power ranges from several seconds to several tens of seconds, and is determined by the time from the engine start to the increase in engine speed and / or the time it takes the battery 1 to absorb the large regenerative power that occurs when the vehicle decelerates, and is at least shorter than the range of time that determines the long-term chargeable power, which will be described later.

[0015] The short-term chargeable power calculation unit 6 calculates an upper limit current that will not cause lithium deposition based on the temperature of the battery 1 and the SOC estimated by the SOC estimation unit 5. The upper limit current indicates the upper limit current value at which lithium deposition will not occur when the battery 1 is charged for a short period of time. The short period corresponds to the short period of short-term chargeable power. The upper limit current is a value determined from the temperature and SOC of the battery 1, and the lower the battery temperature or the higher the SOC, the smaller the upper limit current. The upper limit current is a value experimentally determined depending on the characteristics of the battery 1, etc. The short-term chargeable power calculation unit 6 has a map that associates the temperature, SOC, and upper limit current of the battery 1, and calculates the upper limit current by map calculation using the temperature and SOC of the battery 1 as input.

[0016] Next, the short-term chargeable power calculation unit 6 calculates the internal resistance of the battery 1. The short-term chargeable power calculation unit 6 receives the temperature and SOC of the battery 1 as input and calculates the internal resistance by referring to a map. Alternatively, the short-term chargeable power calculation unit 6 may calculate the internal resistance from the voltage and charge / discharge current of the battery 1 while the vehicle is running and the voltage of the battery 1 is stable. Note that the calculation method for the internal resistance may be other well-known methods.

[0017] The short-term chargeable power calculation unit 6 calculates the voltage that rises due to the internal resistance when an upper limit current is passed through the battery 1 (upper limit current × internal resistance). Furthermore, the short-term chargeable power calculation unit 6 calculates the voltage when the battery 1 is charged with the upper limit current (voltage during upper limit current charging) by adding the calculated voltage (upper limit current × internal resistance) to the OCV corresponding to the SOC of the battery 1. Then, the short-term chargeable power calculation unit 6 multiplies the voltage during upper limit current charging by the upper limit current to calculate the short-term chargeable power (P s1 ) based on the upper limit current. s1 ) is calculated.

[0018] The short-term chargeable power calculation unit 6 calculates the short-term chargeable power (P s1 ), as well as the short-term chargeable power (P s2 ) is calculated. s1 ) is the short-term chargeable power based on the upper limit current that does not cause lithium deposition, and the short-term chargeable power (P s2 ) is the short-term chargeable power based on the upper limit voltage of the battery usable voltage range. The usable voltage of the battery 1 is predetermined to avoid overcharging and overdischarging, and the charge control device 100 controls the charging and discharging of the battery 1 so that the voltage of the battery 1 falls within the usable voltage range.

[0019] Figure 2 is a graph showing the voltage (cell voltage) characteristics (a) and charging power characteristics (b) of battery 1. The horizontal axis of Figure 2 represents time, and the vertical axes represent cell voltage and charging power. When battery 1 is charged, the voltage of battery 1 rises from the OCV due to internal resistance, and follows the characteristics of Figure 2(a).

[0020] The short-term chargeable power calculation unit 6 calculates the short-term chargeable power when the voltage of the battery 1 coincides with the upper limit voltage of the usable voltage range. short term Rechargeable power (P s2) is calculated using the following formula (1). In formula (1), the internal resistance is a short-term internal resistance value and may be calculated based on, for example, the temperature and / or deterioration rate of the battery. The OCV may be calculated from an SOC-OCV map.

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[0021] As a result, the short-term chargeable power calculation unit 6 calculates the short-term chargeable power [P s2 ] is calculated.

[0022] The short-term chargeable power calculation unit 6 calculates the short-term chargeable power (P s1 ) and short-term chargeable power (P s2 ), the smaller power is finally calculated as the short-term chargeable power. As a result, the charge control device 100 according to this embodiment can control the charging of the battery 1 so that the upper limit voltage of the battery usable voltage range is not exceeded while preventing lithium deposition. Note that the short-term chargeable power calculation unit 6 does not necessarily calculate the short-term chargeable power (P s1 ) and short-term chargeable power (P s2 ) is not necessary to be calculated, and either one of the short-term chargeable powers may be calculated. For example, if lithium deposition can be prevented as long as the battery 1 is used at a cell voltage within the usable voltage range due to the setting range of the usable voltage range or the usage environment of the battery 1, the short-term chargeable power calculation unit 6 can calculate at least the short-term chargeable power (P s2 ) can be calculated.

[0023] The long-term chargeable power calculation unit 7 calculates the long-term chargeable power based on the SOC of the battery 1 and the temperature of the battery 1. long term The chargeable power is calculated. The long-term chargeable power is the power that can be used to charge the battery 1 for a long period of time. The long-term chargeable power corresponds to the chargeable power required to complete the warm-up of the battery 1 by charging. The time period for determining the long-term chargeable power is within the range of several hundred seconds to several tens of minutes.

[0024] The long-term chargeable power calculation unit 7 calculates an upper limit current that does not cause lithium deposition based on the temperature of the battery 1 and the SOC estimated by the SOC estimation unit 5, and calculates a long-term chargeable power (P L1 ) is calculated. L1 ) is calculated by the short-term chargeable power calculation unit 6. L1 ) is calculated in the same way. However, the upper limit current is the upper limit current at which lithium does not precipitate when the battery 1 is charged for a long period of time. The internal resistance of the battery 1 is an internal resistance value for a long period of time, and is calculated by referring to a map.

[0025] Next, the long-term chargeable power calculation unit 7 calculates the long-term chargeable power (P L1 ), as well as the long-term chargeable power (P L2 ) is calculated. L1 ) is the long-term chargeable power based on the upper limit current that does not cause lithium deposition, and the long-term chargeable power (P L2 ) is the long-term chargeable power based on the upper limit voltage of the battery's usable voltage range. L2 ) is calculated by the short-term chargeable power calculation unit 6. S2 ) and the calculation formula is the same as formula (1). However, the internal resistance of the battery 1 is a long-term internal resistance value, and may be calculated based on the temperature and / or deterioration rate of the battery, for example. Also, the OCV may be calculated from the SOC-OCV map. This allows the long-term chargeable power calculation unit 7 does not exceed the upper limit voltage based on the temperature and SOC of battery 1 long term Rechargeable power (P L2 ) is calculated.

[0026] The long-term chargeable power calculation unit 7 calculates the long-term chargeable power (P L1 ) and long-term chargeable power (P L2), the smaller power is finally calculated as the long-term chargeable power. As a result, the charge control device 100 according to this embodiment can control the charging of the battery 1 so that the upper limit voltage of the battery usable voltage range is not exceeded while preventing lithium deposition. Note that the long-term chargeable power calculation unit 7, like the short-term chargeable power calculation unit 6, does not necessarily calculate the long-term chargeable power (P L1 ) and long-term chargeable power (P L2 ) is not necessary to calculate the power of both, and the long-term chargeable power of either one may be calculated.

[0027] Figure 3 is a graph showing the response characteristics of short-term chargeable power, medium-term chargeable power, and long-term chargeable power. The graph in Figure 3 shows the change in chargeable power over time when battery 1 is charged with each of the short-term chargeable power, medium-term chargeable power, and long-term chargeable power. The relationship between short-term / long-term chargeable power and battery charging will be explained with reference to the graph in Figure 3.

[0028] Short-term chargeable power (P S1 or P S2 ) is the power that can be charged in the range of several seconds to several tens of seconds or less so that it can absorb the power generated by the increase in engine speed after the start of the engine 30 or the regenerative charging power while the vehicle is running (especially at high speed). On the other hand, the long-term chargeable power (P L1 or P L2 ) is the power that can be charged within a range of several hundred seconds to several tens of minutes so that the charging power required to complete the warm-up of the battery 1 can be secured by charging. Therefore, the short-term chargeable power is greater than the long-term chargeable power. Furthermore, the long-term chargeable power is the power that can be charged over a long period of time, and the short-term chargeable power is the power that can be charged in a shorter period of time than the long period of time.

[0029] When battery 1 is charged with short-term chargeable power, the charging time is short, and when battery 1 is charged with long-term chargeable power, the charging time is long. On the other hand, when short-term chargeable power is used, the chargeable power drops in a short period of time, so charging becomes impossible when it is necessary to absorb regenerative power, for example. Also, when battery 1 is charged with long-term chargeable power, the charging power is small. Although the charging power has a margin compared to the short-term chargeable power, it takes a long time to warm up battery 1 when charging.

[0030] In other words, when the charging of Battery 1 is controlled using only the short-term chargeable power or the long-term chargeable power, charging It is difficult to achieve both a sufficient chargeable power and a long warm-up time. Therefore, the charge control device 100 according to this embodiment calculates the chargeable power by combining the short-term chargeable power and the long-term chargeable power, and controls the charging of the battery 1 based on the calculated chargeable power.

[0031] Referring to FIG. 1 , the chargeable power calculation unit 8 calculates the continuously chargeable power capable of continuously charging the battery 1 based on the short-term chargeable power calculated by the short-term chargeable power calculation unit 6 and the long-term chargeable power calculated by the long-term chargeable power calculation unit 7. FIG. 4 is a block diagram showing functional blocks of the chargeable power calculation unit 8. The chargeable power calculation unit 8 has a target maintenance power calculation unit 81 and a calculation unit 82. The target maintenance power calculation unit 81 calculates the target maintenance power according to the vehicle conditions. The target maintenance power indicates a target value of the chargeable power required to maintain the vehicle's running. The vehicle conditions include the ON / OFF state of the engine 30, the vehicle speed, etc. When the engine 30 is off, the target maintenance power calculation unit 81 calculates the chargeable power prepared for starting the engine 30 as the target maintenance power. When the vehicle speed is high, the target maintenance power calculation unit 81 calculates the chargeable power to be secured in preparation for subsequent regenerative deceleration as the target maintenance power. The target maintenance power calculated according to the vehicle speed increases as the vehicle speed increases. In other words, the target maintenance power is a target value for maintaining short-term chargeable power, and is chargeable power that can absorb regenerative charging power while the vehicle is running and charging power generated by the increase in engine speed after starting the engine of a series hybrid vehicle.

[0032] The calculation unit 82 calculates the continuously chargeable power based on the target maintenance power, the short-term chargeable power, and the long-term chargeable power. First, the calculation unit 82 calculates the power difference (ΔP) by subtracting the target maintenance power from the short-term chargeable power. The calculation unit 82 has a ratio table that defines the usage rate between the short-term chargeable power and the long-term chargeable power. As shown in FIG. 4, the ratio table corresponds the power difference (ΔP) to the usage rate (rate). For example, when the power difference (ΔP) is 5 kW, the usage rate (rate) is 100%. As the power difference (ΔP) decreases, the usage rate (rate) decreases; when the power difference (ΔP) is 1 kW, the usage rate (rate) is 0%. In the example of the ratio table in FIG. 4, the usage rate (rate) decreases by 25% as the power difference (ΔP) decreases by 1 kW from 5 kW. For example, if the battery 1 deteriorates so much that the short-term chargeable power becomes smaller than the target maintenance power and the power difference (ΔP) becomes zero or negative, the usage rate (rate) becomes 0%.

[0033] Next, the calculation unit 82 calculates the continuous chargeable power using the following formula (2).

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[0034] As a result, the chargeable power calculation unit 8 calculates the target maintenance power, and calculates the short-term chargeable power and the target maintenance power. Power and The ratio between the short-term chargeable power and the long-term chargeable power is calculated based on the difference between the short-term chargeable power and the long-term chargeable power, and the continuous chargeable power is calculated based on the calculated ratio.

[0035] Figure 5 shows the response of chargeable power in a time chart. Figure 5 is a graph showing the characteristics of short-term / long-term chargeable power, target maintenance power, actual charging power, and continuously chargeable power. As shown in Figure 5, when the short-term chargeable power has a margin relative to the target maintenance power, that is, when the power difference (ΔP) is large, the proportion of short-term chargeable power is increased to achieve continuous charging. electric powerIn FIG. 5, when the difference between the short-term chargeable power and the target maintenance power is large (ΔP≧5kW), the usage rate of the short-term chargeable power is 100% for the continuous chargeable power. When the short-term chargeable power decreases and the power difference (ΔP) becomes smaller (1kW<ΔP<5kW), the smaller the power difference (ΔP), the lower the usage rate of the short-term chargeable power. Therefore, in the time chart shown in FIG. 5, when the short-term chargeable power becomes smaller, the continuous chargeable power becomes Rechargeable The power decreases at a greater rate than the short-term chargeable power. When the short-term chargeable power becomes even smaller and the power difference (ΔP) becomes smaller (ΔP≦1kW), the usage rate of the short-term chargeable power becomes 0%, and the short-term chargeable power becomes 0%. Rechargeable The power is consistent with the long-term chargeable power.

[0036] In this way, when the short-term chargeable power has a margin relative to the target maintenance power, the chargeable power calculation unit 8 calculates the continuous chargeable power so that the proportion of the short-term chargeable power is higher. On the other hand, when the short-term chargeable power does not have a margin relative to the target maintenance power, the chargeable power calculation unit 8 calculates the continuous chargeable power so that the proportion of the long-term chargeable power is higher. This allows charging when there is a margin between the short-term chargeable power and the target maintenance power, thereby facilitating battery warm-up. When there is not enough margin, charging power is suppressed, thereby maintaining the short-term chargeable power at or above the target maintenance power.

[0037] 1, vehicle controller 20 has a function to control the charging and discharging of battery 1 while managing the state of battery 1, and a function to control the drive system. Vehicle controller 20 generates power by sending a torque command to engine 30 and a rotation speed command to generator 40, and charges battery 1. Vehicle controller 20 also generates the driving force required for running the vehicle by sending a torque command to motor / inverter 50. When charging battery 1, vehicle controller 20 charges battery 1 by limiting the upper limit of the charging power of battery 1 to the continuously chargeable power calculated by chargeable power calculation unit 8.

[0038] Next, with reference to FIG. 6, a control flow of a charging control method executed by a processor included in the charging control device 100 will be described. FIG. 6 is a flowchart of the charging control method. Note that the steps do not necessarily have to be executed in the order shown in FIG. 6, and the order may be changed as appropriate. In step S1, the voltage detection unit 2 detects the voltage of the battery 1. In step S2, the current detection unit 3 detects the current of the battery 1. In step S3, the temperature detection unit 4 detects the temperature of the battery 1. In step S4, the SOC estimation unit 5 estimates the SOC based on the voltage and current of the battery 1. For example, the SOC estimation unit 5 estimates the SOC of the battery 1 by integrating the current flowing through the battery 1, using the SOC calculated from the average voltage of the battery 1 at the time of vehicle startup as an initial value.

[0039] In step S5, short-term chargeable power calculation unit 6 calculates short-term chargeable power based on the temperature and SOC of battery 1. In step S6, long-term chargeable power calculation unit 7 calculates long-term chargeable power based on the temperature and SOC of battery 1. In step S7, chargeable power calculation unit 8 calculates continuous chargeable power based on the short-term chargeable power, long-term chargeable power, and target maintenance power. In step S8, vehicle controller 20 controls charging of battery 1 by limiting the upper limit of charging power to battery 1 to the continuous chargeable power.

[0040] As described above, the charge control method and charge control device according to this embodiment calculate the long-term chargeable power, calculate the short-term chargeable power that is greater than the long-term chargeable power, calculate the continuous chargeable power based on the short-term chargeable power and the long-term chargeable power, and limit the upper limit of the charging power of the battery 1 to the continuous chargeable power. This allows the battery to absorb the power generated depending on the vehicle's driving situation. It also prevents a shortage of chargeable power at extremely low temperatures, enables regenerative charging when the vehicle decelerates, and allows the vehicle to continue driving.

[0041] A characteristic of lithium-ion batteries is that the chargeable power decreases when the battery temperature is low. Therefore, a conventional method for controlling the charging of battery 1 is to reduce the chargeable power as the battery temperature decreases. However, this method of limiting the chargeable power based solely on battery temperature poses the problem that the chargeable power becomes extremely small at low temperatures, making it difficult for the battery to absorb power generated by regenerative power while the vehicle is running or by the increase in engine speed after starting the engine of a series hybrid vehicle. This problem becomes even more pronounced when the low-temperature performance of battery 1 is poor due to deterioration, as the chargeable power at low temperatures decreases even further.

[0042] In the charging control according to this embodiment, the short-term chargeable power is calculated, the long-term chargeable power is calculated, the short-term chargeable power and the long-term chargeable power are combined to calculate the continuous chargeable power, and the upper limit of the battery charging power is limited to the continuous chargeable power, thereby controlling the battery charging in the vehicle drive system. This allows the battery to absorb the power generated depending on the driving situation of the vehicle.

[0043] The charge control method and charge control device according to the present embodiment calculate the target maintaining power, and calculate the short-term chargeable power and the target maintaining power. and The ratio between the short-term chargeable power and the long-term chargeable power is calculated according to the difference, and the continuous chargeable power is calculated according to the ratio. short term When there is a surplus of chargeable power, short term By calculating the continuous chargeable power so that the ratio of chargeable power is increased, a large amount of charging power can be secured and the warm-up of the battery can be promoted. short term When there is not enough chargeable power, long term By calculating the continuously chargeable power so that the proportion of chargeable power is increased, it is possible to prevent the chargeable power from running out and to maintain the running of the vehicle. short term The chargeable power can be maintained at or above the target power, and the engine speed at the start of a series hybrid vehicle can be ofThe battery can absorb the power generated by the engine revving up, allowing the vehicle to continue running.

[0044] Furthermore, the charge control method and charge control device according to this embodiment calculate the short-term chargeable power and the long-term chargeable power based on the upper limit current that prevents lithium deposition. This prevents battery degradation and performance degradation and extends the battery's lifespan. By limiting the upper limit of the battery 1's charging power to the continuous chargeable power, the charging current of the battery 1 is kept below the upper limit current, preventing lithium deposition in the battery.

[0045] Furthermore, the charge control method and charge control device according to this embodiment calculate the short-term chargeable power and the long-term chargeable power based on the upper limit voltage that can be used by the battery 1. This makes it possible to suppress deterioration and performance degradation of the battery and extend its lifespan. By limiting the upper limit of the charging power of the battery 1 to the continuously chargeable power, the charging voltage of the battery 1 is kept below the upper limit voltage, thereby preventing overcharging of the battery.

[0046] Furthermore, the charge control method and charge control device according to this embodiment detect the temperature of the battery 1, calculate the SOC of the battery 1, and calculate the upper limit current based on the temperature and SOC, thereby suppressing deterioration and performance degradation of the battery and extending its lifespan.

[0047] The charge control method and charge control device according to this embodiment detect the temperature of the battery 1, calculate the SOC of the battery 1, and calculate the short-term chargeable power and long-term chargeable power that do not exceed the upper limit voltage based on the temperature and SOC. This makes it possible to suppress deterioration and performance degradation of the battery and extend its lifespan.

[0048] Second Embodiment Next, a charge control device and a charge control method according to a second embodiment will be described. The second embodiment differs from the first embodiment in that it has a deterioration rate estimation unit 9 and an upper limit SOC calculation unit 10. Except for the differences from the charge control device and charge control method according to the first embodiment in the points described below, the second embodiment has the same configuration as the first embodiment and operates or functions in the same way as the first embodiment, and the description of the first embodiment will be incorporated as appropriate. In this embodiment, an upper limit SOC is set in addition to the chargeable power condition, which limits the upper limit of the charging power of the battery 1 to the continuously chargeable power, and if the SOC reaches the upper limit SOC during charging of the battery 1, charging of the battery 1 is controlled.

[0049] 7 is a block diagram showing a drive system according to another embodiment of the present invention. In addition to a voltage detection unit 2 and the like, the charge control device 100 includes a deterioration rate estimation unit 9 and an upper limit SOC calculation unit 10. The deterioration rate estimation unit 9 estimates the deterioration rate of the battery 1 by dividing the current value of the internal resistance of the battery 1 by the initial value of the internal resistance of the battery 1. The initial value of the internal resistance is the internal resistance of the battery when it is new.

[0050] The upper limit SOC calculation unit 10 calculates the upper limit SOC based on the temperature and deterioration rate of the battery 1. The upper limit SOC indicates the upper limit value of the SOC at which the battery 1 can be charged. The upper limit SOC calculation unit 10 calculates the upper limit SOC so that the short-term chargeable power is equal to or greater than the target maintenance power.

[0051] A method for calculating the upper limit SOC will be described with reference to Figures 8 and 9. Figure 8 is a table for explaining the correlation between battery temperature, SOC, short-term chargeable power, and target maintenance power. Figure 9 is a conceptual diagram of a map stored in the upper limit SOC calculation unit 10.

[0052] As a characteristic of the battery 1, the lower the temperature of the battery 1, the smaller the short-term chargeable power, and the higher the SOC, the smaller the short-term chargeable power. Therefore, when the SOC is high in the low temperature range of the battery 1, the short-term chargeable power falls below the target maintenance power. For example, as shown in FIG. 8, when the temperature of the battery 1 is −30°C and the SOC is higher than 60%, the short-term chargeable power falls below the target maintenance power. In this way, if the engine needs to be started when the SOC is high and the short-term chargeable power is lower than the target maintenance power, or if regenerative deceleration is required while driving at high speed, the battery 1 may not be able to charge the power generated by the increase in engine speed or the regenerative power during regenerative deceleration.

[0053] In this embodiment, within a range where the short-term chargeable power falls below the target maintenance power based on the temperature and SOC conditions of the battery 1, an upper limit SOC is set to limit charging so that the short-term chargeable power does not fall below the target maintenance power. Specifically, the upper limit SOC calculation unit 10 has a map (upper limit SOC calculation map) as shown in FIG. 9 that correlates the temperature, deterioration rate, and upper limit SOC of the battery 1, and calculates the upper limit SOC using the map. The upper limit SOC calculation map is a map for calculating the upper limit SOC using the temperature and deterioration rate of the battery 1 as input. In the SOC calculation map, in the low temperature region of the battery 1 (for example, a region where the deterioration rate is 100% (like-new condition) and the temperature is less than 0 deg. C), the lower the battery temperature, the smaller the upper limit SOC. The upper limit SOC in the portion enclosed by the dotted line in FIG. 9 corresponds to the target maintenance power in FIG. 8. That is, when the deterioration rate is 100% and the temperature of the battery 1 is −30° C., the upper limit SOC is limited to 60%, thereby preventing the short-term chargeable power from falling below the target charge power.

[0054] Furthermore, the temperature range in which the upper limit SOC is limited to less than 100% depending on the battery temperature gradually expands toward higher temperatures as the battery 1 deteriorates, further lowering the upper limit SOC. As the battery 1 deteriorates, its internal resistance increases and the chargeable power decreases, so the relationship between the battery temperature and the upper limit SOC is set on a map in accordance with each deterioration rate. As a result, the upper limit SOC is set in the upper limit SOC calculation map so that the short-term chargeable power is equal to or greater than the target maintenance power. Note that the values in FIG. 9 are merely examples and can be changed as appropriate depending on the characteristics of the battery 1, etc.

[0055] In addition to the above calculation method using the upper limit SOC calculation map, upper limit SOC calculation unit 10 may calculate the upper limit SOC in the following manner: Figure 10 is a block diagram showing the control flow of the method of calculating the upper limit SOC by upper limit SOC calculation unit 10.

[0056] As shown in formula (1) of the first embodiment, the target sustained power is calculated from the upper limit voltage, the internal resistance, and the OCV. When the OCV is replaced with the upper limit OCV in formula (1), the following formula (3) is derived.

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[0057] Furthermore, by expanding equation (3), the following equation (4) for determining the upper limit SOC is derived.

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[0058] The target maintenance power is determined by the vehicle conditions. The upper limit voltage is determined in advance by the usable voltage range according to the characteristics of battery 1. The internal resistance is calculated from the current / voltage of battery 1. Therefore, by substituting these parameters into equation (4), the upper limit OCV can be calculated. inFurthermore, as shown in Fig. 10, upper limit SOC calculation unit 10 refers to a relationship table between OCV and SOC, and calculates the SOC corresponding to the calculated upper limit OCV as the upper limit SOC. As a result, upper limit SOC calculation unit 10 calculates the upper limit OCV at which the short-term chargeable power is equal to or greater than a predetermined power based on the upper limit voltage, target maintenance power, and internal resistance, and calculates the upper limit SOC corresponding to the upper limit OCV.

[0059] Referring to FIG. 7, the vehicle controller 20 acquires the upper limit SOC from the upper limit SOC calculation unit 10, and charges the battery 1 by limiting the upper limit of the SOC of the battery 1 to the upper limit SOC.

[0060] Next, the control flow of the charge control method by the charge control device 100 will be described with reference to Fig. 11. Fig. 11 is a flowchart of the charge control method. Note that the steps do not necessarily have to be executed in the order shown in Fig. 11, and the order may be changed as appropriate. The control flow of steps S11 to S17 is the same as steps S1 to S7 in the first embodiment, and therefore description thereof will be omitted.

[0061] In step S18, the deterioration rate estimation unit 9 estimates the deterioration rate of the battery from the average voltage and current of the battery 1. In step S19, the upper limit SOC calculation unit 10 calculates the upper limit SOC based on the temperature and deterioration rate of the battery 1 so that the short-term chargeable power is equal to or greater than the target maintenance power. In step S20, the vehicle controller 20 controls the charging of the battery 1 by limiting the upper limit of the charging power to the battery 1 to the continuously chargeable power and limiting the SOC of the battery 1 to the upper limit SOC.

[0062] As described above, the charge control method and charge control device according to this embodiment detect the temperature of battery 1, calculate the deterioration rate of battery 1, calculate the upper limit SOC of battery 1 based on the temperature and deterioration rate, limit the SOC of battery 1 to the upper limit SOC, and charge battery 1. In this way, by setting the upper limit SOC, it is possible to ensure chargeable power and maintain vehicle running. Furthermore, since battery 1 has a characteristic in which chargeable power decreases as the SOC increases, it is possible to ensure chargeable power while taking battery 1 deterioration into consideration by setting the upper limit SOC when charging in accordance with the battery temperature and deterioration rate.

[0063] The charge control method and charge control device according to this embodiment have a map that correlates the temperature, degradation rate, and upper limit SOC of the battery 1, and calculates the upper limit SOC using the map. The upper limit SOC is set in the map so that the short-term chargeable power is equal to or greater than the target maintenance power. This makes it possible to secure the chargeable power by setting the upper limit of the SOC, and to maintain the vehicle's running.

[0064] Furthermore, the charge control method and charge control device according to this embodiment estimate the internal resistance of the battery, calculate an upper limit OCV at which the short-term chargeable power is equal to or greater than a predetermined power (corresponding to the target maintenance power) based on the usable upper limit voltage, target maintenance power, and internal resistance of the battery 1, calculate an upper limit SOC corresponding to the upper limit OCV, and limit the SOC of the battery to the upper limit SOC before charging the battery. In this way, by setting an upper limit for the SOC, chargeable power can be secured and vehicle operation can be maintained.

[0065] Third Embodiment Next, a charge control device and a charge control method according to a third embodiment will be described. The third embodiment includes a warm-up determination unit 11, in contrast to the first embodiment. Note that, except for the differences from the charge control device and charge control method according to the first embodiment in the points described below, the third embodiment has the same configuration as the first embodiment and operates or functions in the same way as the first embodiment, and the descriptions of the first and / or second embodiments are incorporated as appropriate. Note that a deterioration rate estimation unit 9 and an upper limit SOC calculation unit 10 may be added to this embodiment, and the battery 1 may be controlled under the control described in the second embodiment.

[0066] 12 is a block diagram showing a drive system according to another embodiment of the present invention. The charge control device 100 includes a warm-up determination unit 11 in addition to a voltage detection unit 2, etc. The warm-up determination unit 11 determines whether warm-up of the battery 1 is complete based on the temperature of the battery 1 detected by the temperature detection unit 4 and the chargeable power calculated by the chargeable power calculation unit 8, and outputs the warm-up determination result to the vehicle controller 20.

[0067] The warm-up determination method will be described with reference to Fig. 13. Fig. 13 is a block diagram showing the control flow of the warm-up determination method by the warm-up determination unit 11. The warm-up determination unit 11 performs warm-up determination using a chargeable power condition and a temperature condition. The warm-up determination unit 11 determines that warm-up is complete when the two conditions are met. The warm-up determination unit 11 determines that warm-up is not complete when the two conditions are not met. The warm-up determination unit 11 determines whether warm-up is complete after warm-up by charging the battery 1 has started.

[0068] The warm-up determination power threshold is a threshold that indicates whether the chargeable power required for warming up the battery 1 can be secured when warming up the battery 1 by charging the battery 1. The warm-up determination power threshold is a preset threshold that is set to a power higher than the target maintenance power. The warm-up determination power threshold is a threshold that is set so that the short-term chargeable power does not fall below the target maintenance power again after warm-up completion determination is made.

[0069] The warm-up determination unit 11 measures the state in which the continuous chargeable power is higher than the warm-up determination power threshold using a timer, and determines that the chargeable power condition is met when the measurement time (counter) reaches a predetermined time. On the other hand, the warm-up determination unit 11 determines that the chargeable power condition is not met when the continuous chargeable power is lower than the warm-up determination power threshold or when the duration (measurement time) of the state in which the continuous chargeable power is higher than the warm-up determination power threshold is less than a predetermined time.

[0070] The warm-up determination unit 11 has temperature thresholds with hysteresis, including a first temperature threshold and a second temperature threshold, as temperature conditions. The second temperature threshold is higher than the first temperature threshold. The warm-up determination unit 11 compares the temperature of the battery 1 with the first and second temperature thresholds. If the temperature of the battery 1 is equal to or lower than the first temperature threshold, the warm-up determination unit 11 sets a flag indicating that the battery is being warmed up. If the temperature of the battery 1 is equal to or higher than the first temperature threshold but lower than the second temperature threshold, the flag is set. Then, if the temperature of the battery 1 is equal to or higher than the second temperature threshold, the flag is cleared. The warm-up determination unit 11 performs a NOT operation on the state of the flag, and if the flag is not set, determines that the temperature condition for determining whether warm-up is complete is met. If the flag is set, the warm-up determination unit 11 determines that the battery is being warmed up and that the temperature condition for determining whether warm-up is complete is not met.

[0071] FIG. 14 shows various parameters related to the warm-up determination and a time chart of the warm-up determination result. (a) shows the time chart at extremely low temperatures, and (b) shows the time chart at low temperatures. Referring to FIG. 14(a), at extremely low temperatures, the temperature of the battery 1 starts from a state below the first temperature threshold, and the battery is warming up. to As a result, the temperature of the battery 1 gradually rises. When the continuously chargeable power increases and exceeds the warm-up determination power threshold, a timer starts counting. When the temperature of the battery 1 exceeds the second temperature threshold and the counter reaches a predetermined time, the warm-up determination unit 11 determines that warm-up is complete.

[0072] At low temperatures, the temperature of the battery 1 starts from a state where the temperature is equal to or higher than the first temperature threshold, and warm-up has not yet started. When the temperature of the battery 1 drops below the first temperature threshold, the vehicle controller 20 starts warm-up. The warm-up determination unit 11 determines that the battery is being warmed up. During warm-up, continuous charging The available power is reduced and the warm-up is judged electric power When the temperature becomes lower than the threshold value, the warm-up determination unit 11 resets the counter by the timer. charging Available power determines warm-up Power Threshold 14(b), the counter reaches the predetermined time before the temperature of the battery 1 reaches the second temperature threshold, and the warm-up determination unit 11 determines that the chargeable power condition is satisfied. Thereafter, when the temperature of the battery 1 rises and reaches the second temperature threshold, the warm-up determination unit 11 determines that the temperature condition is satisfied in addition to the chargeable power condition, and therefore determines that warm-up is complete.

[0073] 12, when the warm-up determination unit 11 determines that the battery 1 is being warmed up, the vehicle controller 20 limits the upper limit of the charging power of the battery 1 to the continuously chargeable power. When the warm-up determination unit 11 determines that the warm-up is complete, the vehicle controller 20 limits the upper limit of the charging power to the normal chargeable power, for example, the short-term chargeable power or the medium-term chargeable power. The medium-term chargeable power is the power that can be charged in the time between the short term and the long term (corresponding to the "medium-term chargeable power" in FIG. 3).

[0074] Next, the control flow of the charge control method by the charge control device 100 will be described with reference to Fig. 15. Fig. 15 is a flowchart of the charge control method. The control flow in Fig. 15 is a flow executed during warm-up of the battery 1. Note that the steps do not necessarily have to be executed in the order shown in Fig. 15, and the order may be changed as appropriate. The control flow of steps S21 to S27 is the same as steps S1 to S7 in the first embodiment, and therefore description thereof will be omitted.

[0075] In step S28, the warm-up determination unit 11 determines whether or not the warm-up of the battery 1 has been completed based on the temperature of the battery 1 detected by the temperature detection unit 4 and the chargeable power calculated by the chargeable power calculation unit 8. If it is determined that the warm-up has not been completed, in step S29, the vehicle controller 20 limits the upper limit of the charging power to the battery 1 to the continuously chargeable power, and controls the charging of the battery 1. If it is determined that the warm-up has been completed, the vehicle controller 20 limits the upper limit of the charging power to the battery 1 to the normally chargeable power, and controls the charging of the battery 1. (S30) .

[0076] As described above, the charge control method and charge control device according to this embodiment determine whether warming up of the battery 1 is complete based on the temperature and continuous chargeable power of the battery 1. In this way, by determining that warming up of the battery is complete, it is possible to switch to normal chargeable power calculation.

[0077] It should be noted that the above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments are intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Explanation of symbols]

[0078] 1 battery 2 Voltage detection section 3 Current detection section 4 Temperature detection unit 5 SOC estimation section 6 Short-term chargeable power calculation section 7 Long-term rechargeable power calculation section 8 Rechargeable power calculation section 9 Deterioration rate estimation section 10 Upper limit SOC calculation section 11 Warm-up determination section 20 Vehicle Controller 30 Engine 40 Generator 50 Motor / Inverter 100 Charging control device

Claims

1. A charge control method for controlling charging of a battery including a lithium ion battery provided in a vehicle, the method being executed by a processor, comprising: The processor: calculating a long-term chargeable power that is the power capable of charging the battery for a long period of time; calculating a short-term chargeable power that is a power capable of charging the battery for a short period of time and is greater than the long-term chargeable power; calculating a continuously chargeable power capable of continuously charging the battery based on the short-term chargeable power and the long-term chargeable power; A charging control method for limiting the upper limit of the charging power of the battery to the continuously chargeable power.

2. 2. The charge control method according to claim 1, The processor: calculating a target maintenance power indicating a target value of chargeable power required to maintain running of the vehicle; calculating a ratio of the short-term chargeable power to the long-term chargeable power according to a difference between the short-term chargeable power and the target maintenance power; A charging control method for calculating the continuously chargeable power in accordance with the ratio.

3. 3. The charge control method according to claim 1, The processor: A charging control method for calculating the short-term chargeable power and the long-term chargeable power based on an upper limit current that does not cause lithium deposition.

4. The charge control method according to any one of claims 1 to 3, The processor: A charging control method for calculating the short-term chargeable power and the long-term chargeable power based on an upper limit voltage usable by the battery.

5. 4. The charge control method according to claim 3, The processor: Detecting the temperature of the battery; Calculating the SOC of the battery; A charging control method for calculating the upper limit current based on the temperature and the SOC.

6. 5. The charge control method according to claim 4, The processor: Detecting the temperature of the battery; Calculating the SOC of the battery; A charging control method for calculating the short-term chargeable power and the long-term chargeable power based on the temperature and the SOC, the short-term chargeable power and the long-term chargeable power not exceeding the upper limit voltage.

7. The charge control method according to any one of claims 1 to 4, The processor: Detecting the temperature of the battery; Calculating a deterioration rate of the battery; calculating an upper limit SOC at which the battery can be charged based on the temperature and the deterioration rate; A charge control method for charging the battery by limiting the SOC of the battery to the upper limit SOC.

8. 8. The charge control method according to claim 7, The processor: a map in which the temperature, the deterioration rate, and the upper limit SOC correspond to each other; Calculating the upper limit SOC using the map; the upper limit SOC is set in the map so that the short-term chargeable power is equal to or greater than a target maintenance power; The target maintenance power indicates a target value of chargeable power required to maintain the vehicle's running.

9. The charge control method according to any one of claims 1 to 4, The processor: Estimating an internal resistance of the battery; calculating an upper limit OCV at which the short-term chargeable power is equal to or greater than a predetermined power based on a usable upper limit voltage of the battery, a target maintenance power indicating a target value of chargeable power required to maintain running of a vehicle equipped with the battery, and the internal resistance; Calculating an upper limit SOC corresponding to the upper limit OCV; A charge control method for charging the battery by limiting the SOC of the battery to the upper limit SOC.

10. The charge control method according to any one of claims 1 to 4, The processor: Detecting the temperature of the battery; A charging control method for determining whether warm-up of the battery has been completed based on the temperature and the continuously chargeable power.

11. a controller that controls charging of a battery provided in a vehicle, the battery including a lithium ion battery; The controller calculating a long-term chargeable power that is the power capable of charging the battery for a long period of time; calculating a short-term chargeable power that is a power capable of charging the battery for a short period of time and is greater than the long-term chargeable power; calculating a continuously chargeable power capable of continuously charging the battery based on the short-term chargeable power and the long-term chargeable power; a charge control device that limits the upper limit of the charging power of the battery to the continuously chargeable power;

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