TWM506414U - Large electric vehicle battery supply system capable of replacing battery cell at site and formed by having buffer battery and battery pack - Google Patents

Description

Large electric vehicle battery supply system that can be replaced in the field and has a buffer battery and a battery pack

This creation is about a battery supply system, especially a large electric vehicle battery supply system that can replace a single battery in the field and has a buffer battery and a battery pack.

The basic structure of the traditional large-scale electric vehicle lithium battery system is composed of single cells. Since the voltage of the single lithium battery is generally between 3.2V and 4.2V, the large electric vehicle needs a high voltage driving motor, and its voltage is 576V. A large number of series connections are required between ~600V. And the single lithium battery has low energy, so it needs a lot of parallel connection. Based on the above situation, a large-capacity large-scale electric lithium battery is formed by a complicated and large number of series-parallel connection. Due to the high energy density ratio, the single lithium battery has the following characteristics: 1. Based on the factory manufacturing process, material properties, and environmental conditions, the chemical reactions of the single cells are not completely the same. 2. In actual use, due to the difference in installation position temperature, the charge/discharge current is quickly charged, resulting in a change in the characteristics of the battery substrate. 3. The isolation of the single cell separator due to external forces causes different leakage conditions.

Therefore, after a period of use of the single cell, the voltage and the stored energy will gradually differ. After the battery cells are connected in parallel to form a battery module, when a single When the battery voltage and stored energy are lower or higher than other batteries. The inside of the battery module will form a reflow and a voltage imbalance will occur. If this phenomenon is not improved (voltage consistency), when the cell voltage of a battery string is too high, it will cause its own battery string to be fully charged but the other battery strings cannot be fully charged. When the cell voltage of a battery string is too low, the battery string will be over-discharged when the entire system is discharged, resulting in deterioration of the cell and possible formation of load heat, which causes the battery to burn.

At present, lithium battery factories, in order to meet the user's habits, mostly in accordance with the customer's voltage and capacity requirements, first with a single battery string into a 24V/48V@50AH/100AH battery module. The battery module is connected in series to a high voltage battery string. In accordance with the demand for the capacity of the electric vehicle, a plurality of battery strings are connected in parallel by a DC bus, and a motor directly supplied to the electric vehicle is formed. The system is equipped with a battery monitoring system to monitor the voltage of the battery module, to detect the consistency of the battery module voltage at any time, and to avoid the disaster caused by the characteristics of the battery module. This design has the following advantages and disadvantages:

Advantages: 1. The series-parallel process is simple. 2. The battery monitor uses the battery module as the monitoring unit, the number of monitoring is greatly reduced, and the cost of the battery monitor is saved.

Disadvantages: 1. The inside of the battery module is made up of a series of parallel cells, and the battery monitor cannot monitor the condition of the single battery. 2. The abnormality of the single battery causes the battery module to be abnormal. Although the battery monitor is abnormally monitored and reminded to replace it, since the battery has been subjected to a large number of series and parallel connection and a huge amount of energy is formed, the battery string is to be Battery module replacement is not easy and dangerous. 3. If the battery module is updated or repaired abnormally, after the battery string is formed, since the voltage of the battery string and the voltage of the DC bus are not equal, it is not possible to directly connect in parallel, and it is necessary to discharge the voltage of the two terminals through resistance discharge or other means. The process of paralleling is very cumbersome. 4. When a certain battery is replaced, because the new battery has good characteristics, it is easy to form a battery string voltage during charging, but since the battery string is connected in parallel to the DC bus, the battery string voltage cannot be increased, except for forming a battery string reflow. In addition, in this battery string, the battery with poor characteristics will continue to be affected, and a vicious cycle will be formed for a long time, which will indirectly affect the life of the battery pack. 5. The battery system is directly connected to the motor through the bus bar. When the vehicle starts and brakes, there will be an instantaneous large discharge current and an instantaneous large return current flow. The inrush current is not good for the long-term life of the lithium battery. 6. After detecting the abnormality of the battery module, the battery monitor sends it back to the battery factory. The battery factory must disassemble the battery module into a battery unit and then check one by one. After replacing the abnormal single battery, it is combined back to the battery module. However, the old and new single battery String, characteristics can not be controlled, battery module performance is not easy to maintain. 7. The busbar voltage will drop one by one as the battery system discharges, and its voltage variation can be as high as 25%.

Therefore, the present invention hopes to propose a new battery supply system for replacing a single battery in the field and having a large electric vehicle formed by a buffer power pool and a battery pack to solve the defects of the prior art.

Therefore, the purpose of this creation is to solve the above-mentioned problems in the prior art, and propose a battery cell that can be replaced in the field and has a buffer battery and a battery pack. The large electric vehicle battery supply system has the advantages of using the buffer battery string to be responsible for the instantaneous high current of the vehicle starting and braking, protecting other battery strings (lithium batteries), and prolonging the life of other battery strings; each battery cell of the battery string is Monitor and balance the circuit to ensure the balance of the cells in the battery string at any time; the battery string is connected to the main bus through the DC bidirectional DC to DC voltage converter, and each battery string can be adjusted according to the needs of its own equalization circuit. String voltage (does not affect other battery strings).

In order to achieve the above object, a large electric vehicle battery supply system formed by replacing a single battery in the field and having a buffer battery and a battery pack is provided in the present invention, comprising: a battery pack comprising: a total bus bar comprising two rows The wires are respectively the first row wire and the second row wire, and the first row wire and the second row wire have opposite polarities, and the two wire wires may additionally connect or serially connect at least one load to provide power of the battery pack. At the load; at least one battery string, the battery strings are connected in parallel between the two rows of wires. The battery string is composed of a plurality of battery modules connected in series, wherein the battery modules are formed by a plurality of single cells in series or in parallel; at least one DC to DC voltage converter each of the DCs (direct current , DC) to DC voltage converter is connected between the corresponding first line and the battery string, for converting the unspecified voltage on the battery string side into the fixed system voltage on the first line side; by turning off the DC to The DC voltage converter can make the battery string out of the total busbar for the repair of the battery string; in the charging and discharging operation, the DC to DC voltage converter can independently perform the battery string Charge and discharge, so different battery strings do not interfere with each other.

The case also contains four novel features: 1. With a buffer battery string, responsible for the instantaneous high current of the vehicle start and brake. 2. With voltage balance control system, can balance the voltage of each battery string. 3. There are several DC to DC voltage converters for adjusting the output voltage of each battery string to maintain a fixed system voltage. 4. It has a single battery detection system, which can detect the status of each single battery and send out an abnormal signal.

The features of the present invention and its advantages can be further understood from the description below, and please refer to the attached drawings when reading.

10‧‧‧Battery string

11‧‧‧Battery module

12‧‧‧ single battery

13‧‧‧Voltage/current measuring device

14‧‧‧Voltage/current measurement processor

15‧‧‧ memory

16‧‧‧Logical unit

17‧‧‧Alarms and displays

20‧‧‧Battery battery string

21‧‧‧Buffered battery module

22‧‧‧Single buffer battery

30‧‧‧Balance circuit bus

31‧‧‧ positive line

32‧‧‧negative cable

40‧‧‧balancer

50‧‧‧Battery string controller

60‧‧‧Communication bus

100‧‧‧ total bus

111‧‧‧Battery Module Controller

200‧‧‧Sub-bus

300‧‧‧load

311‧‧‧ positive secondary line

312‧‧‧Actual relay

321‧‧‧negative secondary line

322‧‧‧Negative relay

400‧‧‧DC to DC voltage converter

Figure 1 shows a block diagram of the components of the present invention.

Figure 2 shows another block diagram of the components of the present invention, which also includes a voltage balance control system.

Figure 3 shows a schematic diagram of the voltage balance control system of the present case.

FIG. 4 shows a single cell detection system of the present invention, which is applied to a schematic diagram of a single cell.

FIG. 5 shows a single buffer battery detection system of the present invention, which is applied to a schematic diagram of a single buffer battery.

I would like to discuss the structure of the case and the functions and advantages that can be produced. In conjunction with the drawings, a preferred embodiment of the present invention is described in detail below.

Referring to FIG. 1 to FIG. 5, a large electric vehicle battery supply system formed by replacing a single battery in the field and having a buffer battery and a battery pack can be displayed, and the battery system can output a high volt voltage to For large electric vehicles (such as electric buses), the current high voltage can be 300V (volts), 440V, 576V, 600V. The battery system of this case contains the following components: a battery pack, which contains: The flow row 100 includes two rows of wires, which are respectively a first row wire and a second row wire. The first row wire and the second row wire have opposite polarities, and the two row wires may additionally connect or serially connect at least one load 300. To provide power of the battery pack to the load 300. In this paper, a parallel motor is used as the load 300, but this is not intended to limit the scope of the present case.

At least one battery string 10, these battery strings 10 are connected in parallel between the two rows of wires. The battery string 10 is constructed by connecting a plurality of battery modules 11 in series. The battery module 11 is constructed by connecting a plurality of unit cells 12 in series or in parallel.

The case has the following four novel characteristics:

(1) with buffer battery string 20

The at least one battery string 10 includes at least one buffer battery string 20 connected in parallel to the total bus bar 100. The buffer battery string 20 is configured by a plurality of buffer battery modules 21 in series. The buffer battery module 21 is composed of a plurality of single buffer batteries 22 connected in series or in parallel. The single buffer battery 22 is one of a lead acid battery, a lithium titanate battery or a super capacitor.

The buffer battery string 20 is suitable for applications of inrush current (instantaneous large capacity charging/discharging), and the instantaneous inrush current does not drastically affect the buffer battery string 20. Therefore, when the load 300 of the entire power supply system suddenly rises (such as when the vehicle starts or brakes) and the current increases sharply, the buffer battery string 20 can quickly increase the supplied current to meet the needs of the system.

Other battery strings 10 (generally a battery string 10 formed by a lithium battery, hereinafter described with a lithium battery) are connected in parallel to the total bus bar 100; the lithium battery is suitable for deep cycle charge and discharge characteristics and high energy density ratio due to lithium battery The pool is not suitable for applications with inrush current (instantaneous large capacity charging/discharging). Instantaneous inrush current affects the life of the lithium battery, so the system uses a lithium battery as the power supply for steady-state current, which can extend the life of the entire system.

In operation, when the load 300 of the system suddenly rises (such as when the vehicle is started or braked), the buffer battery string 20 can quickly provide the required instantaneous inrush current and be supplied to the load 300 together with the other battery strings 10. When the current supply of the total bus bar 100 reaches a stable value, the other battery strings 10 are used as the main supply current source, and the current supply ratio of the buffer battery string 20 is lowered.

(2) Voltage balance control system

The present invention further includes at least one voltage balance control system, in combination with the at least one battery string 10, comprising: a sub-bus bar 200, wherein the plurality of battery modules 11 are connected in series to the sub-bus bar 200, the sub-current stream The row 200 is connected to the total busbar 100.

A balancer 40 having a voltage balancing function is connected to the sub-bus bar 200 for balancing the voltages of the respective battery modules 11 in the battery string 10 to prevent voltages of certain battery modules 11 from being opposite to voltages of other battery modules 11. Too high or too low.

A balancing circuit bus 30 includes a positive line 31 and a negative line 32. One end of the positive electrode cable 31 is connected to the positive input end of the balancer 40, and the other end is divided into a plurality of parallel positive secondary line 311. The ends of the respective positive secondary lines 311 are connected to the positive output terminals of the respective corresponding battery modules 11. In the corresponding battery module 11, each of the positive secondary lines 311 includes a corresponding positive relay 312, which can be used to control the current flowing through the positive secondary line 311.

One end of the negative electrode cable 32 is connected to the negative input of the balancer 40. The other end is divided into a plurality of parallel negative sub-lines 321 . The ends of the respective negative secondary lines 321 are connected to the negative output terminals of the respective corresponding battery modules 11. In the corresponding battery module 11, each of the negative secondary lines 321 includes a corresponding negative relay 322, which can be used to control the current flowing through the negative secondary line 321.

a plurality of battery module controllers 111, wherein each of the battery module controllers 111 is connected to a corresponding battery module 11 for detecting voltages of the respective battery modules 11 at the ends of the series bus bar 200; and the battery The module 11 controller can be used to control the negative relay 322 of the negative secondary line 321 and the positive relay 312 of the positive secondary line 311. The battery module controller 111 can also be used to measure the temperature of each of the battery modules 11.

A battery string controller 50 can be used to control the current of the entire battery string 10 to achieve a balanced voltage of each of the battery modules 11. The battery string controller 50 is connected to the battery module 11 controller of each of the battery modules 11 through a communication bus 60 (such as RS-485, RJ-45, and the like). The battery string controller 50 is still connected to the balancer 40 through another communication bus 60; the battery string controller 50 still controls that only one battery module 11 of the positive relay 312 and the negative relay 322 will be turned on each time, and the rest Will close.

During operation, each of the battery module controllers 111 measures the voltage of each of the battery modules 11 and transmits the voltage back to the battery string controller 50. The battery string controller 50 determines the voltage to deviate from the average voltage according to a predetermined logic. The battery module 11 is too large to balance the current via the balancer 40. The default logic is such that after averaging the voltages of all the battery modules 11, the difference between the voltage and the voltage average of the battery module 11 exceeds a predetermined ratio (for example, 20%), that is, the enthalpy is too large, so the voltage must be performed. balance.

At this time, the battery string controller 50 reports the balancer 40 to the battery module 11 to be subjected to voltage balancing, and notifies the battery module controller 111 of the battery module 11 to communicate with the negative relay 322 of the negative secondary line 321 and the positive electrode. The positive relay 312 of the sub-line 311. The battery module 11 and the balancer 40 form a current loop for communication.

(C) several DC to DC voltage converters 400

The case also includes several DC to DC voltage converters 400: each DC (direct current) to DC voltage conversion The device 400 is connected between the corresponding first cable and the battery string 10. The buffer battery string 20 is not connected in series with the DC to DC voltage converter 400. The DC to DC voltage converter 400 has a balance of the battery. The voltage output function of the string 10 is used to convert an unspecified voltage on the battery string 10 side into a fixed system voltage on the first line side.

The function of the DC to DC voltage converter 400 is that the voltages across the battery strings 10 are not equal when the system is in operation, so that during operation, the battery string 10 with a lower voltage will become the load 300 and will absorb the remaining high. The energy of the voltage battery string 10 makes the overall battery output unable to reach the expected target value, and the battery life will be shortened in the long run. The DC to DC voltage converter 400 will cause the voltage of each battery string 10 to be a fixed system voltage, so that the above-described load 300 effect will not occur.

By turning off the DC to DC voltage converter 400, the battery string 10 can be detached from the main busbar 100 to perform the refurbishment work of the battery string 10. When the total busbar 100 is short-circuited, the battery string 10 has DC to DC voltage. The isolation protection of the converter 400 is therefore safer to apply.

During the charging and discharging operation, the DC to DC voltage converter 400 can independently charge and discharge the battery string 10, so that different battery strings 10 do not interfere with each other, each The battery string 10 is independently charged and discharged.

(4) Single cell detection system

The present invention further includes a single battery detection system, each of which is connected to each of the battery modules 11, the single battery detection system includes: a plurality of voltage/current measuring devices 13, and each voltage/current measuring device 13 is used for the amount The output voltage/current values of the connected one or several unit cells 12 are measured, and the voltage/current values are transmitted outward.

A voltage/current measuring processor 14 receives the measured values from the plurality of voltage/current measuring devices 13 and performs a summation process; a memory 15 is built in the voltage/current measuring processor 14, The voltage/current measurement processor 14 is configured to store a value of the voltage/current measurement processor 14; the voltage/current measurement processor 14 includes a logic unit 16 having a logic judgment and operation function, and the logic unit 16 can determine each according to a predetermined logic. Whether the unit cell 12 is operating normally or not, when the logic unit 16 determines that the voltage/current of the unit cell 12 is abnormal, the abnormality information of the unit cell 12 is output to remind the maintenance personnel to replace the unit cell 12.

An alarm device and a display unit 17 are connected to the logic unit 16 to receive abnormal information of the unit battery 12 and displayed in the display The alarm will sound a warning to alert the operator or maintenance personnel.

The single cell detecting system can independently detect the power supply state of each of the single cells 12, so that the faulty single cells 12 can be quickly found for replacement, and the entire battery module 11 does not need to be disassembled, and then the faulty ones are checked one by one. The unit cell 12, and since there is a voltage balance control system in the present case, the voltage value of the battery module 11 can be balanced, so that the problem that the voltage of the battery unit 11 is higher after replacing the new unit cell 12 can be minimized.

The above single cell detection system can be applied to the buffer battery string 20, which is called a single buffer battery detection system, except that the battery module 11 is a buffer battery module 21, and the single battery 12 It is a single buffer battery 22, and the rest of the application methods are the same.

The advantages of this case are as follows: 1. Use the buffer battery string to be responsible for the instantaneous high current of the vehicle starting and braking, protect other battery strings (lithium batteries), and extend the life of other battery strings. Since the buffer battery string may have a long life due to a large amount of instantaneous charging and discharging current, the buffer battery string can be replaced separately, and the cost is far more than the entire battery system replacement, which has a reduced cost. 2. Each cell of the battery string is monitored and a balancing circuit is implemented to ensure the uniformity of the cells in the battery string at any time. 3. The battery string is connected to the total busbar through a DC bidirectional DC to DC voltage converter, and each battery string can be adjusted according to the needs of its own equalization circuit. String voltage (does not affect other battery strings). 4. When detecting the abnormality of the single battery, as long as the DC bidirectional DC to DC voltage converter is turned off, the total busbar can be disconnected and the battery string can be repaired in the field. When the battery string is repaired or updated, although the battery string voltage is different from the others, it can be easily isolated by DC to DC voltage converter, integrated into the bus bar and On-Line, safe and easy to maintain. 5. Each battery string is self-balanced and controlled, and is not affected by the total busbar voltage, and the balance is easy. 6. During charging, the DC to DC voltage converter can be used to fully charge the battery string according to the required voltage and current. It is not possible to continue charging because the voltage string of the other group has reached the high limit after all the parallel connections. During discharge, the battery string energy can be continuously converted to the total bus through the DC to DC voltage converter to ensure the capacity of the battery discharge. 7. When the total busbar is short-circuited, since the battery strings are isolated by DC to DC voltage converters, the short-circuit energy is small and the application is safer. 8. Due to the isolation and conversion of the DC to DC voltage converter, the total bus voltage variation rate is low, which is suitable for the use of motors and appliances on the vehicle. 9. Large-scale electric vehicles can adapt to different types of charger voltages through DC to DC voltage converters because the charging voltage level varies according to the regulations of each country or region. The large electric vehicle adopts the battery system, and it is not necessary to replace the battery system design in response to the demand of the voltage or capacity of the chargers in various places.

In summary, the innovative design of this case is quite in line with actual needs. The specific improvement of the existing defects is obviously a breakthrough improvement advantage compared with the prior art, and it has an improvement in efficacy and is not easy to achieve. The case has not been disclosed or It has been in compliance with the patent law in the literature and market exposed at home and abroad.

The detailed description above is a detailed description of one of the possible embodiments of the present invention, and the embodiment is not intended to limit the scope of the patents, and the equivalent implementations or modifications that are not included in the spirit of the present invention should be included in The patent scope of this case.

10‧‧‧Battery string

11‧‧‧Battery module

20‧‧‧Battery battery string

21‧‧‧Buffered battery module

100‧‧‧ total bus

300‧‧‧load

400‧‧‧DC to DC voltage converter

Claims (7)

A large electric vehicle battery supply system capable of replacing a single battery in the field and having a buffer battery and a battery pack, comprising: a battery pack comprising: a total bus bar comprising two rows of wires, respectively being the first row of wires And the second row of wires, the first row of wires and the second row of wires have opposite polarities, and the two rows of wires may additionally or in series connect at least one load to provide power of the battery pack to the load; at least one battery string The battery strings are connected in parallel between the two rows of wires. The battery string is composed of a plurality of battery modules connected in series, wherein the battery modules are connected in series or in parallel by a plurality of single cells. The method comprises: at least one DC to DC voltage converter, each DC (direct current) to DC voltage converter is connected between the corresponding first cable and the battery string, and is used for unspecifying the battery string side The voltage is converted into a fixed system voltage on the first line side; by turning off the DC to DC voltage converter, the battery string can be disengaged from the total bus bar for battery string refurbishment; during charge and discharge operation, the DC To DC Of the converter may be charged and discharged independent of the cell strings, and therefore different cell string where no mutual interference occurs between each other. A large electric vehicle battery supply system formed by replacing a single battery in the field and having a buffer battery and a battery pack, wherein the at least one battery string further includes at least one buffer battery string connected in parallel to the total current. Row, the buffer battery string is constructed by a series of buffer battery modules in series The buffer battery module is composed of a plurality of single buffer batteries in series or in parallel, and the single buffer battery is one of a lead acid battery, a lithium titanate battery or a super capacitor; The load of the system suddenly rises, the buffer battery string can quickly provide the required instantaneous inrush current, and is supplied with the other battery strings to the load; when the current supply of the total bus bar reaches a stable value, other battery strings are used. In order to supply the current source mainly, the current supply ratio of the buffer battery string is lowered. A large electric vehicle battery supply system formed by replacing a single battery in the field and having a buffer battery and a battery pack, as in claim 1, further comprising at least one voltage balance control system, combined with the at least one battery string, The method includes: a sub-bus bar, wherein the plurality of battery modules are connected in series to the sub-bus bar, the sub-bus bar is connected to the main bus bar; a balancer having a voltage balancing function, connecting the sub-bus a bus bar for balancing the voltage of each battery module in the battery string to prevent the voltage of some battery modules from being too high or too low relative to the voltage of other battery modules; a balance circuit bus bar comprising a positive circuit cable and a Negative cable. Wherein one end of the positive electrode cable is connected to the positive input end of the balancer, and the other end is divided into a plurality of parallel positive secondary line; the end of each positive secondary line is connected to the positive output end of each corresponding battery module; In the corresponding battery module, each The positive secondary line includes a corresponding positive relay that can be used to control current flowing through the positive secondary line; one end of the negative line is connected to the negative input of the balancer, and the other end is divided into a plurality of a parallel negative secondary line, the end of each negative secondary line is connected to a negative output end of each corresponding battery module; in the corresponding battery module, each negative secondary line includes a corresponding negative relay, the negative relay The utility model can be used for controlling a current flowing through the negative secondary line; a plurality of battery module controllers, wherein each of the battery module controllers is respectively connected to a corresponding one of the battery modules, and can be used for detecting the corresponding battery modules in the serial connection The voltage at both ends of the row; and the battery module controller can be used to control the negative relay of the negative secondary line and the positive relay of the positive secondary line, and the battery module controller can also be used to measure the temperature of each battery module; A string controller can be used to control the current of the entire battery string to achieve a balance of voltages of the battery modules. The battery string controller is connected to the battery module controller of each of the battery modules through a communication bus, wherein the battery string controller is connected to the balancer through another communication bus; the battery string controller controls each operation Only the positive and negative relays of one battery module will be turned on, and the rest will be turned off. As for the large electric vehicle battery supply system formed by replacing the single battery in the field and having the buffer battery and the battery pack, the single battery detection system is also included in each of the battery modules. monomer The battery detection system comprises: a plurality of voltage/current measuring devices, each voltage/current measuring device is used for measuring the output voltage/current value of the connected one or several single cells, and the voltage/current is The value is transmitted outward; a voltage/current measuring processor receives the measured values from the plurality of voltage/current measuring devices and summarizes the processing; a memory is used to store the value of the voltage/current measuring processor The voltage/current measurement processor includes a logic unit having a logic judgment and calculation function, and the logic unit can determine whether each of the single cells operates normally according to a predetermined logic, and when the logic unit determines a certain monomer When the voltage/current of the battery is abnormal, the abnormal information of the single battery is output to remind the maintenance personnel to replace the single battery. For example, in the second application of the patent scope, a large electric vehicle battery supply system formed by replacing a single battery in the field and having a buffer battery and a battery pack includes a single buffer battery detection system, each of which is connected to each of the buffer battery modules. The single buffer battery detection system comprises: a plurality of voltage/current measuring devices, wherein each voltage/current measuring device is used for measuring the output voltage/current value of the corresponding one or several single buffer batteries connected And transmitting the voltage/current value outward; a voltage/current measuring processor receiving the measured values from the plurality of voltage/current measuring devices and summing them; a memory for storing the value of the voltage/current measurement processor; the voltage/current measurement processor includes a logic unit having a logic judgment and operation function, and the logic unit can determine each of the singles according to a predetermined logic Whether the body buffer battery is in normal operation, when the logic unit determines that the voltage/current of a single buffer battery is abnormal, the abnormal information of the single buffer battery is output to remind the maintenance personnel to replace the single buffer battery. A large electric vehicle battery supply system formed by replacing a single battery in the field and having a buffer battery and a battery pack, as in claim 4, further includes an alarm device and a display connected to the logic unit to receive the single battery The abnormal information is displayed on the display, and the alarm sounds a warning to alert the operation or maintenance personnel. A large electric vehicle battery supply system formed by replacing a single battery in the field and having a buffer battery and a battery pack, as in claim 5, includes an alarm device and a display connected to the logic unit to receive the unit buffer Abnormal information about the battery and displayed on the display, and the alarm will sound a warning to alert the operation or maintenance personnel.