Battery management system and method for agricultural electric vehicle

Abstract

The present invention relates to a battery management technology for an agricultural electric vehicle. A battery management system for an agricultural electric vehicle according to the present invention may identify the voltage of a low-voltage battery when charging a high-voltage battery, and activate or deactivate a voltage converter on the basis of the identified voltage value, thereby increasing the charging speed of the high-voltage battery.

Description

Battery management system and management method for agricultural electric vehicles

[0001] The present invention relates to a battery management technology for an agricultural electric vehicle.

[0002] Agricultural work vehicles are vehicles developed for agricultural work.

[0003] Agricultural work vehicles include tractors, combines, and rice transplanters.

[0004] Agricultural work vehicles are continuously being developed and evolved to make farming easier.

[0005] Recently, advances in battery technology have led to the development of electric agricultural vehicles.

[0006] Agricultural electric vehicles have both high-voltage and low-voltage batteries. For example, high-voltage batteries provide 350 V of power, while low-voltage batteries provide 12 V.

[0007] High-voltage batteries replace the internal combustion engines of the past.

[0008] High-voltage batteries are mainly used to secure driving power for power-intensive driving or agricultural work.

[0009] The power of the high-voltage battery is discharged to drive high-voltage electrical loads such as drive motors and hydraulic pumps.

[0010] The power of the low-voltage battery is discharged to drive low-voltage electrical loads such as lights and various control devices.

[0011] Discharged high-voltage batteries and low-voltage batteries require charging.

[0012] High-voltage batteries are charged by external power.

[0013] Charging of low-voltage batteries is done by power from high-voltage batteries or external power.

[0014] In a situation where external power is not connected, charging of the low-voltage battery (120) depends on the power of the high-voltage battery (110), as shown in the reference diagram of Fig. 1.

[0015] As shown in Fig. 1, when charging of a low-voltage battery (120) is performed using the power of a high-voltage battery (110), discharging of the high-voltage battery (110) is accompanied.

[0016] In a situation where an external power source is connected and a high-voltage battery (110) is being charged, the charging of the low-voltage battery (120) depends on the external power source, as shown in the reference diagram of FIG. 2.

[0017] As shown in Fig. 2, the external power provided through the charger (FM) is divided in the power relay (140). Some of the divided external power is used to charge the high-voltage battery (110), and the remaining external power is used to charge the low-voltage battery (120).

[0018] As shown in FIGS. 1 and 2, a voltage converter (130) is provided to charge a low-voltage battery (120) with power from a high-voltage battery (110) or external power.

[0019] A voltage converter (130) is installed between a power relay (140) and a voltage battery (120).

[0020] The voltage converter (130) is called a so-called LDC (Low Voltage DC-DC Converter).

[0021] Previously, lead-acid batteries were used as low-voltage batteries for 12V.

[0022] Lead-acid batteries have the advantage of being rechargeable even after over-discharge, but they are heavy and have a low charge density. Lead acid is also an environmental pollutant.

[0023] For various reasons, there is a recent trend towards using lithium-ion batteries as 12V low-voltage batteries.

[0024] Lithium-ion batteries have a critical weakness: they cannot be recharged if over-discharged. When lithium-ion batteries are used, the power output from the voltage converter (130) must be designed to charge the low-voltage battery (120), thereby maintaining the stability of the low-voltage battery (120).

[0025] When charging a high-voltage battery (110), the voltage converter (130) is implemented to be constantly operated to ensure stabilization of the low-voltage battery (120).

[0026] While research and development of agricultural electric vehicles (EVs) is accelerating in line with the trend toward eco-friendliness, widespread adoption remains limited. One of the many reasons for this slow adoption is the excessive charging time of the high-voltage batteries used in agricultural EVs. Slow charging, rather than rapid charging, requires charging times exceeding six hours. This explains why various research efforts are actively underway to increase the charging speed of agricultural EVs.

[0027] [Prior Art Literature]

[0028] [Patent Document]

[0029] (Patent Document 1) Republic of Korea Publication No. 10-2022-0073891

[0030] (Patent Document 2) Republic of Korea Publication No. 10-2018-0063571

[0031] (Patent Document 3) Republic of Korea Publication No. 10-2022-0117033

[0032] Battery management technologies that can improve charging speeds in agricultural electric vehicles need to continue to be proposed.

[0033] A battery management system for an agricultural electric vehicle according to the present invention comprises: a high-voltage battery that provides high-voltage power and can be charged with external power; a low-voltage battery that provides low-voltage power lower than that of the high-voltage battery and can be charged with the power of the high-voltage battery or external power; a voltage converter that converts the power of the high-voltage battery to low voltage and supplies the power to the low-voltage battery and low-voltage electrical loads; and a controller that, when charging of the high-voltage battery begins, checks the voltage of the low-voltage battery and controls the voltage converter to be activated or deactivated.

[0034] The controller controls the voltage converter to be deactivated when the voltage of the low-voltage battery is higher than a first set value in a charging mode in which the high-voltage battery is charged, and after deactivating the voltage converter, controls the voltage converter to be activated when the voltage of the low-voltage battery is lower than a second set value that is lower than the first set value so that the low-voltage battery is charged.

[0035] The above controller controls the low-voltage electric loads to operate by power from the low-voltage battery when the voltage converter is disabled in the charging mode.

[0036] Charging of the above low-voltage battery is performed in a state where the power of the above low-voltage battery is not supplied to the low-voltage electrical loads.

[0037] The above controller activates the voltage converter in charging mode and then controls the voltage converter to be deactivated when the storage capacity of the low-voltage battery is greater than or equal to a third set value.

[0038] The first set value is a voltage value at which the low-voltage electric loads operating in the charging mode can be operated with the power of the low-voltage battery, and the second set value is a voltage value at which charging of the low-voltage battery can be started without causing damage to the low-voltage battery.

[0039] A battery management method for an agricultural electric vehicle according to the present invention comprises: a first confirmation step of confirming whether the voltage of a low-voltage battery is higher than a first set value when charging of a high-voltage battery starts; a deactivation step of deactivating a voltage converter if the voltage of the low-voltage battery is confirmed to be higher than the first set value in the first confirmation step; and, after the deactivation step, a second confirmation step of confirming whether the voltage of the low-voltage battery is lower than a second set value; and an activation step of activating the voltage converter if the voltage of the low-voltage battery is confirmed to be lower than the first set value in the first confirmation step or lower than the second set value in the second confirmation step; wherein the first confirmation step, the deactivation step, the second confirmation step, and the activation step are performed in a charging mode in which a high-voltage battery is charged, and the second set value is a voltage value lower than the first set value.

[0040] After the above activation step, a third confirmation step is further included to confirm whether the storage capacity of the low-voltage battery is equal to or greater than a third set value; and if the storage capacity of the low-voltage battery is equal to or greater than the third set value in the third confirmation step, the system enters the deactivation step.

[0041] According to the present invention, there is an effect of improving the charging speed of a high-voltage battery while maintaining the stability of a low-voltage battery.

[0042] Figures 1 and 2 are reference drawings for explaining the prior art.

[0043] Figure 3 is a configuration diagram of a battery management system for an agricultural electric vehicle according to one embodiment of the present invention.

[0044] Figure 4 is a reference diagram for explaining a power distributor applied to the management system of Figure 1.

[0045] Figures 5 and 6 are reference drawings for explaining the operating status of the management system of Figure 3.

[0046] Figure 7 is a flowchart for explaining a battery management method performed in the management system of Figure 3.

[0047] A preferred embodiment according to the present invention is described with reference to the attached drawings, but for the sake of brevity, descriptions of well-known components are omitted or compressed as much as possible.

[0048] FIG. 3 is a configuration diagram of a battery management system (200, hereinafter abbreviated as “management system”) for an agricultural electric vehicle according to one embodiment of the present invention.

[0049] The management system (200) of FIG. 3 includes a high-voltage battery (210), a low-voltage battery (220), a voltage converter (230), a power relay (240), and a controller (250).

[0050] The high-voltage battery (210) provides high-voltage (DC 360 V) power used as driving power for agricultural electric vehicles or for agricultural work.

[0051] The low voltage battery (220) provides power at a lower voltage (DC 12 V) than the high voltage battery (210).

[0052] The operation of turning on / off the starter of an agricultural electric vehicle, operating various lights, and controlling various operations is performed using the power of a low-voltage battery (220).

[0053] The present invention primarily considers the application of a lithium-ion battery as a low-voltage battery (220). However, the present invention does not exclude the application of a lead-acid battery as a low-voltage battery (220).

[0054] The voltage converter (230) converts the high voltage power of the high voltage battery (210) into low voltage power.

[0055] A voltage converter (230) is placed between a high-voltage battery (210) and a low-voltage battery (220).

[0056] A voltage converter (230) is placed between a power relay (240) and a low-voltage battery (220).

[0057] A voltage converter (230) is placed between the high-voltage battery (210) and the low-voltage electric loads (LL).

[0058] A voltage converter (230) is placed between a power relay (240) and low-voltage electrical loads (LL).

[0059] The low-voltage power output from the voltage converter (230) is provided to low-voltage electric loads (LL) including a low-voltage battery (220) or a controller (250).

[0060] The voltage converter (230) can be activated or deactivated under the control of the controller (250).

[0061] The power relay (240) relays high voltage power provided from a high voltage battery (210) or charger (FM) to a voltage converter (230).

[0062] The power relay (240) is a power distributor or includes a power distributor.

[0063] The power relay (240) can distribute the power of the high-voltage battery (210) to high-voltage electrical loads.

[0064] Referring to Fig. 4, the power relay (240) distributes power to an electric motor (M), a hydraulic motor (P), a heater (H), a fan motor (F), a compressor (C), and a voltage converter (230).

[0065] The controller (250) may be the highest level control means among many control means applied to agricultural electric vehicles.

[0066] The controller (250) manages all other control means applied to the agricultural electric vehicle.

[0067] The top-level controller (250) in an agricultural electric vehicle is commonly called an EVCU (Electric Vehicle Controller Unit).

[0068] The controller (250) can ultimately control the operation of all controllable electric loads by controlling the control means of the lower stages.

[0069] However, the controller (250) may be a separate control means provided to comprehensively direct the charging process according to the needs of the present invention.

[0070] The controller (250) can control the voltage converter (230) to activate or deactivate.

[0071] The controller (250) checks the voltage of the low-voltage battery (120) and controls the voltage converter (230) to be activated or deactivated.

[0072] For example, when charging of a high-voltage battery (210) begins, if the voltage of the low-voltage battery (220) is higher than the first set value (e.g., '11 V'), the controller (250) controls the voltage converter (230) to be deactivated.

[0073] When the voltage converter (230) is deactivated, power from the low-voltage battery (220) is supplied to the low-voltage electric loads (LL).

[0074] For example, when charging of a high-voltage battery (210) begins, if the voltage of the low-voltage battery (120) is lower than the second set value (e.g., '10.5 V'), the controller (250) controls the voltage converter (230) to be activated.

[0075] When the voltage converter (230) is activated, the low-voltage battery (220) is charged and the power output from the voltage converter (230) is supplied to the low-voltage electric loads (LL).

[0076] The controller (250) can check the storage capacity of the low-voltage battery (220) during the charging process.

[0077] The storage capacity can be calculated as a ratio.

[0078] When the total possible storage capacity is 100%, the storage amount confirmed by the controller (250) theoretically has a value between 0 and 100%.

[0079] The controller (250) controls the voltage converter (230) to be deactivated according to the storage amount of the low-voltage battery (220) during the charging process.

[0080] For example, if the storage capacity of the low-voltage battery (220) is greater than the third set value (e.g., '90%'), the controller (250) controls the voltage converter (230) to be deactivated.

[0081] The controller (250) controls the control means related to the control of high-voltage electric loads to be switched to a dormant state.

[0082] High voltage electrical loads may be electric motors (M) or hydraulic motors (P).

[0083] The power generated by the electric motor (M) is mainly used for driving agricultural electric vehicles and for farm work.

[0084] The power produced by the hydraulic motor (P) is mainly used for agricultural work.

[0085] For reference, let's look at the high voltage loads and low voltage loads (LL) mentioned above.

[0086] Electrical loads refer to electrical components that discharge a high-voltage battery (210) or a low-voltage battery (220) by consuming power.

[0087] The electrical loads are divided into high-voltage electrical loads and low-voltage electrical loads (LL).

[0088] High voltage electrical loads consume power from the high voltage battery (210).

[0089] Low voltage loads (LL) consume power from the low voltage battery (220).

[0090] High voltage electrical loads may include electric motors (M), hydraulic motors (P), and compressors (C).

[0091] Low voltage loads (LL) may include various lights, ignition on / off keys, on board charges (OBC), and various control devices.

[0092] The OB-C is a voltage converter. The OB-C converts AC power from an electric vehicle charging device (EVSE: Electric Vehicle Supply Equipment) into DC power and supplies it to a high-voltage battery (210).

[0093] Various control means include a controller (250).

[0094] Various control means also include a BMS (Battery Management System), an EVCC (Electric Vehicle Communication Controller), a TCU (Transmission Control Unit), and a hydraulic control means located at the lower end of the controller (250).

[0095] BMS performs the functions of battery voltage monitoring, battery temperature monitoring, current control, battery error diagnosis and protection.

[0096] BMS can monitor the charging process and manage it with an optimal charging algorithm to ensure safe and efficient charging.

[0097] The electric vehicle communication controller checks whether the BMS and OBC are ready for charging and communicates this information to the electric vehicle charging device.

[0098] The TCU controls the electronically operated transmission.

[0099] The hydraulic control means controls the hydraulic pressure.

[0100] According to the management system (200) according to the present invention, the voltage converter (130) may not be continuously operated after charging begins. Instead, the voltage converter (130) may be activated or deactivated.

[0101] Figure 5 illustrates a state in which the voltage converter (230) is activated after charging has started.

[0102] Referring to Fig. 5, external power coming from the charger (FM) is divided in the power relay (240), some of which is supplied to the high-voltage battery (210), and the remaining part is supplied to the voltage converter (230).

[0103] The low-voltage power output from the voltage converter (230) is supplied to the low-voltage battery (220) and low-voltage electric loads (LL).

[0104] In the state of Fig. 5, as in the past, the external power from the charger (FM) cannot be fully used to charge the high-voltage battery (210).

[0105] In general, the electric energy conversion efficiency of the voltage converter (230) is less than 90%.

[0106] Among the power coming from the charger (FM), only the remaining power, after subtracting the portion for charging the low-voltage battery (220) and the portion for operating the low-voltage electric loads (LL) and the portion for loss due to the conversion efficiency of the voltage converter (230), is used to charge the high-voltage battery (210).

[0107] When the controller (250) deactivates the voltage converter (230), the state changes to that of Fig. 6.

[0108] In the state of Fig. 6, no power is output from the voltage converter (230).

[0109] The controller (250) controls the low-voltage electric loads (LL) to operate using the power of the low-voltage battery (220).

[0110] The state of Fig. 5 and the state of Fig. 6 can be appropriately switched according to the control of the controller (250).

[0111] The controller (250) selectively activates or deactivates the voltage converter (230) depending on whether a specific condition is satisfied.

[0112] The management system (200) according to the present invention can contribute to increasing the charging speed of a high-voltage battery (210), especially in the charging mode for the high-voltage battery (210).

[0113] In charging mode, the controller (250) activates or deactivates the voltage converter (230) while checking the status of the low-voltage battery (220).

[0114] As shown in Fig. 6, when the voltage converter (230) is deactivated, the power from the charger (FM) is not used to charge the low-voltage battery (220) or operate the low-voltage electrical loads (LL). Instead, all power from the charger (FM) is used entirely to charge the high-voltage battery (210). Accordingly, the charging speed of the high-voltage battery (210) increases.

[0115] Below, a preferred example of a battery management method performed in an agricultural electric vehicle equipped with the management system (200) of FIG. 3 is examined together with the flow chart of FIG. 7.

[0116] Figure 7 is a flowchart of a battery management method performed in charging mode. For convenience, the sequence is explained with reference to Figure 7.

[0117] 1. Some control measures are dormant. <s11>

[0118] When charging of the high-voltage battery (210) begins, the controller (250) deactivates the lower-level control means related to controlling high-voltage electrical loads operated by high-voltage power, thereby switching to a dormant state. This is to prevent unnecessary power leakage in the charging mode.

[0119] In charging mode, operation of the controller (250), electric vehicle communication controller, BMS and OBC is required.

[0120] Charging mode does not allow for driving or agricultural work on electric agricultural vehicles. Charging mode does not require TCU or hydraulic control.

[0121] The controller (250) controls the TCU or hydraulic control means, which do not require a role, to be switched to a dormant state.

[0122] When various control means not directly related to charging are switched to a dormant state, the charging speed of the high-voltage battery (210) can be increased because there is no waste of power.

[0123] It is most desirable to implement step S11 so that it is performed first when charging starts after switching to charging mode.

[0124] However, step S11 may be implemented to be performed at any point in the process in which steps S12 to S15 described below are performed.

[0125] For reference, when charging of the high-voltage battery (210) begins, some high-voltage electrical loads that are not related to charging of the high-voltage battery (210) or low-voltage battery (220) also enter a dormant state.

[0126] 2. First confirmation <s12>

[0127] The controller (250) checks whether the voltage of the low-voltage battery (220) is higher than a first set value. The first set value is a voltage value preset in the controller (150).

[0128] It is preferable that the first setting value be a voltage value that allows the operation of low-voltage electric loads (LL) operating in charging mode with the power of the low-voltage battery (220) to be performed properly.

[0129] As an example, the first setting value in a low voltage battery (120) for 12 V may be 11 V.

[0130] 3. Disable the voltage converter <s13>

[0131] If the voltage of the low voltage battery (220) is higher than the first set value in step S12, the controller (150) deactivates the voltage converter (230) to switch to the state of FIG. 6.

[0132] When the voltage converter (230) is deactivated, the controller (250) controls the low-voltage electric loads (LL) to operate by the power of the low-voltage battery (220).

[0133] After step S13, the controller (250), electric vehicle communication controller, BMS and OBC operate on power from the low voltage battery (220).

[0134] When step S13 is performed, the power supplied from the charger (FM) to the low-voltage battery (220) or the low-voltage electronic loads (LL) via the voltage converter (130) is eliminated. All power from the charger (FM) is used to charge the high-voltage battery (210), and the charging speed of the high-voltage battery (210) increases accordingly.

[0135] 4. Second confirmation <s14>

[0136] With the voltage converter (230) disabled, the controller (250) continuously checks whether the voltage of the low-voltage battery (220) is below the second set value.

[0137] The second setting value is also a voltage value preset in the controller (250).

[0138] It is desirable that the second setting value be a voltage value at which charging can begin appropriately while the low-voltage battery (220) is discharged to a level that does not cause damage.

[0139] The second setting value is lower than the first setting value.

[0140] As an example, the second setting value in a low voltage battery (220) for 12 V may be 10.5 V.

[0141] Since the voltage of the low-voltage battery (120) is continuously checked through step S14 while the voltage converter (230) is disabled, it is possible to immediately respond to maintaining the stability of the low-voltage battery (120) while utilizing the power of the low-voltage battery (120) during the charging process.

[0142] 5. Activate the voltage converter <s15>

[0143] In step S12, if the voltage of the low-voltage battery (220) is lower than the first set value, the controller (250) activates the voltage converter (230) to switch to the state of FIG. 5.

[0144] Also, if the voltage of the low voltage battery (220) is lower than the second set value in step S14, the controller (250) activates the voltage converter (230) to switch to the state of FIG. 5.

[0145] In the state of Fig. 5, the voltage converter (230) operates, so a portion of the power coming from the charger (FM) is charged to the low-voltage battery (220).

[0146] The low-voltage electric loads (LL) controller (250), electric vehicle communication controller, BMS and OBC also operate on power output from the voltage converter (230).

[0147] The meaning of activation in step S15 also includes the meaning of maintaining the state of the voltage converter (230) that was previously activated.

[0148] The activation of the voltage converter (230) immediately after step S12 means that the activated state of the voltage converter (230) that is already activated is maintained.

[0149] The activation of the voltage converter (230) that is performed sequentially after going through steps S13 and S14 in step S12 means activating the voltage converter (230) that was deactivated.

[0150] 6. Third confirmation <s16>

[0151] The controller (250) checks whether the storage capacity of the low-voltage battery (220) is equal to or greater than the third set value after the voltage converter (230) is activated by step S15.

[0152] The third setting value is a value preset in the controller (250).

[0153] As an example, the third set value may be a percentage value of the total storage capacity of the low voltage battery (220). For example, the third set value may be a percentage value of 90% of the total storage capacity of the low voltage battery (120).

[0154] If the storage capacity is greater than the third set value, the controller (250) determines that the low-voltage battery (220) is sufficiently stable and controls the process to proceed to step S13. Accordingly, the management system (200) transitions to the state of FIG. 6, and the charging speed of the high-voltage battery (210) increases.

[0155] According to the present invention, the activation and deactivation of the voltage converter (230) is determined based on the voltage value of the low-voltage battery (220). This can be particularly well combined with the special situation of charging mode.

[0156] Charging can be started and stopped at will by the administrator. The charging time can be adjusted by the administrator at any time. Therefore, it is more desirable to determine the activation or deactivation of the voltage converter (230) based on the voltage value of the low-voltage battery (220) rather than the battery capacity of the low-voltage battery (220).

[0157] On the other hand, it is more desirable that the condition for entering step S13 from step S16 be based on the storage capacity of the low-voltage battery (220).

[0158] The voltage value can also be used as a reference when transitioning from step S16 to step S13. For example, in the case of a low-voltage battery with an output voltage of 12 V, the third setting value can be set to 12 V.

[0159] If the storage capacity of the low-voltage battery (220) is above a certain value, the output voltage of the low-voltage battery (220) is constant at 12 V. In this case, the detection of the third set value is performed at the lowest storage capacity that can output 12 V. If implemented in this way, the cyclic flow that passes through S16, S13, S14, and S15 and then returns to S16 can be repeated many times during the charging process for the high-voltage battery (210).

[0160] The numerous repetitions of the cyclic flow require power consumption due to frequent control, which reduces the charging speed of the high-voltage battery (210).

[0161] Since the present invention is for stabilizing a low-voltage battery (220), it is also necessary to charge the low-voltage battery (220) so that the low-voltage battery (220) has a sufficiently stable storage capacity.

[0162] For that reason, it is preferable that the condition for entering S13 from step S16 be based on the storage capacity rather than the voltage of the low-voltage battery (120).

[0163] The cyclic flow consisting of steps S13, S14, S15, and S16 can be performed as needed throughout the charging time.

[0164] However, in the case of rapid charging, the power required for the operation of the controller (250) and the like during the charging time can be sufficiently handled by the storage capacity of the low-voltage battery (220). In this case, all power from the charger (FM) can be used to charge the high-voltage battery (210) throughout the charging time.

[0165] <Difference between the first and second settings>

[0166] In one example, the first setting value is 11 V and the second setting value is 10.5 V. The reason for making a difference between the first and second setting values ​​is to reduce the operating time of the voltage converter (230) as much as possible.

[0167] For example, even if the voltage of the low-voltage battery reaches 10.7 V, the voltage converter (230) remains inactive. This allows the voltage converter (230) to remain inactive for a longer period of time.

[0168] Therefore, there is an advantage in that the time for which only the high-voltage battery (210) can be charged can be increased. This contributes to improving the charging speed of the high-voltage battery (210).

[0169] Additionally, there is an advantage in that the operating time of the voltage converter (230) can be reduced, thereby reducing the heat generation time. Since the total heat generation amount is reduced, the power consumption resulting from the need to cool the voltage converter (230) using a thermal management device can be reduced.

[0170] Ultimately, the charging speed of the high-voltage battery (210) is improved by making the second setting value as low as possible compared to the first setting value.

[0171] The above-described embodiments merely illustrate preferred examples of the present invention, and it may have various applications. Therefore, the present invention should not be construed as limited to the above-described content. Instead, the scope of the present invention should be construed within the scope of the separately described claims and their equivalents.

Claims

1. A high-voltage battery (210) that provides high-voltage power and can be charged with external power; A low-voltage battery (220) that provides low-voltage power lower than that of the high-voltage battery (210) and can be charged with power from the high-voltage battery (210) or external power; A voltage converter (230) that converts the power of the high-voltage battery (210) into low voltage and supplies it to the low-voltage battery (220) and low-voltage electrical loads (LL); and When charging of the high-voltage battery (210) starts, a controller (250) is included that checks the voltage of the low-voltage battery (220) and controls the voltage converter (230) to be activated or deactivated; Battery management system for agricultural electric vehicles (200).

2. In paragraph 1, The above controller (250) controls the voltage converter (230) to be deactivated when the voltage of the low voltage battery (220) is higher than the first set value in the charging mode in which the high voltage battery (210) is charged, and after deactivating the voltage converter (230), controls the voltage converter (230) to be activated when the voltage of the low voltage battery (220) is lower than the second set value which is lower than the first set value so that the low voltage battery (220) is charged. Battery management system for agricultural electric vehicles (200).

3. In paragraph 2, The above controller (250) controls the low-voltage electric loads (LL) to operate by the power of the low-voltage battery (220) when the voltage converter (230) is deactivated in the charging mode. Battery management system for agricultural electric vehicles (200).

4. In paragraph 2, Charging of the above low voltage battery (220) is performed in a state where the power of the above low voltage battery (220) is not supplied to the low voltage electric loads (LL). Battery management system for agricultural electric vehicles (200) 5. In paragraph 2, The above controller (150) activates the voltage converter (130) in the charging mode and then controls the voltage converter (130) to be deactivated when the storage amount of the low voltage battery (120) is greater than the third set value. Battery management system for agricultural electric vehicles (200).

6. In paragraph 2, The above first set value is a voltage value at which the operation of the low-voltage electric loads (LL) operating in the charging mode can be performed with the power of the low-voltage battery (220). The above second setting value is a voltage value that can start charging the low voltage battery (220) without causing damage to the low voltage battery (220). Battery management system for agricultural electric vehicles (200).

7. When charging of the high-voltage battery (210) begins, the first confirmation step is performed to check whether the voltage of the low-voltage battery (220) is higher than the first set value. <s12> ;< / s12> The first verification step above <s12>When the voltage of the low voltage battery (220) is confirmed to be higher than the first set value, a deactivation step is performed to deactivate the voltage converter (230). <s13> ; and< / s13> The above deactivation step <s13>Afterwards, a second verification step is performed to check whether the voltage of the low-voltage battery (220) is less than the second set value. <s14> ; and< / s14> The first verification step above <s12>In the above low voltage battery (220), the voltage is confirmed to be below the first set value or the second confirmation step <s14>When the voltage of the low voltage battery (220) is confirmed to be less than the second set value, an activation step for activating the voltage converter (230) <s15> ; including,< / s15> The first verification step above <s12>, the above deactivation step <s13>, the second verification step above <s14>and the above activation step <s15> It is carried out in charging mode where a high-voltage battery (110) is charged.< / s15> The above second setting value is a lower voltage value than the above first setting value. Battery management method for agricultural electric vehicles.

8. In paragraph 7, The above activation step <s15>Afterwards, a third confirmation step is performed to check whether the storage capacity of the low-voltage battery (220) is greater than or equal to the third set value. <s16> ; including more,< / s16> The third verification step above <s16>If the storage capacity of the low voltage battery (220) is greater than the third set value, the deactivation step <s13> Entering into< / s13> Battery management method for agricultural electric vehicles.

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