A power battery maintenance device

Abstract

This application provides a power battery maintenance device, which includes an on-board charger, a DC-DC converter, a controller, and a slow-charging socket for connecting to an AC charging station. The power battery, maintenance device, and AC charging station can form a high-voltage circuit and a low-voltage circuit. Specifically: the high-voltage interface of the slow-charging socket and the on-board charger are interconnected; the high-voltage interface of the on-board charger, the DC-DC converter, and the power battery are interconnected to form a high-voltage circuit. The low-voltage interface of the slow-charging socket and the on-board charger are interconnected; the low-voltage interface of the on-board charger, the controller, the DC-DC converter, and the power battery are interconnected to form a low-voltage circuit. Since only operators need to connect the device, the power battery, and the AC charging station, the operation is very simple. It eliminates the need for professional personnel to perform charging, discharging, and equalization maintenance on the power battery, and also eliminates the need for maintenance at the power battery supplier, making it highly suitable for widespread use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy vehicles, in particular to a power battery maintenance device. BACKGROUND

[0002] The power battery of a new energy vehicle usually adopts a lithium ion battery, which inevitably causes self-discharge. Therefore, the power battery that has been stored for a long time needs to be charged and maintained to prevent over-discharge and thus cause the power battery to be scrapped. Moreover, the power battery is composed of a plurality of battery cells, and the number of battery cells is dozens to hundreds or even thousands. The self-discharge rates of the battery cells are inconsistent, and thus the power battery needs to be regularly balanced and maintained.

[0003] The current situation is as follows:

[0004] (1) The power battery is charged and discharged and balanced and maintained by professional charging and discharging equipment and by professional personnel, and the maintenance is usually performed at the power battery supplier. Since the professional charging and discharging equipment is expensive and requires high site and personnel, the promotion of the use is limited, and thus it is not conducive to the promotion of the use by manufacturers, 4S stores, repair service stores, etc.

[0005] (2) The power battery is mounted on a vehicle, and the vehicle is used to charge and discharge the power battery, such as charging and balancing when the balancing condition is met. The power battery needs to be replaced each time, and since the power battery is heavy, usually several hundred kilograms, professional disassembly tools are required, which is time-consuming and laborious.

[0006] (3) The power battery is charged and maintained by a direct current fast charging pile. The coverage range of the direct current fast charging pile is relatively small compared with that of the alternating current charging pile, and thus the applicability is poor. SUMMARY

[0007] In view of at least one of the above defects or deficiencies in the prior art, the present application aims to provide a power battery maintenance device.

[0008] According to the first aspect, the power battery maintenance device comprises a vehicle-mounted charger, a DC-DC converter, a controller and a slow charging socket for connecting an alternating current charging pile, and a high-voltage loop and a low-voltage loop can be formed between the power battery and the maintenance device, wherein:

[0009] The slow charging socket and the high-voltage interface of the vehicle-mounted charger are interconnected, and the vehicle-mounted charger, the DC-DC converter and the high-voltage interface of the power battery are interconnected to form the high-voltage loop; the slow charging socket and the low-voltage interface of the vehicle-mounted charger are interconnected, and the vehicle-mounted charger, the controller, the DC-DC converter and the low-voltage interface of the power battery are interconnected to form the low-voltage loop;

[0010] In the high-voltage circuit, the on-board charger is configured to convert the high-voltage AC power source from the AC charging pile through the slow charging socket into a high-voltage DC power source, and supply the high-voltage DC power source to the DC-DC converter and the power battery; in the low-voltage circuit, the DC-DC converter is configured to convert the high-voltage DC power source into a low-voltage DC power source, so that the low-voltage DC power source powers the DC-DC converter, the controller, the on-board charger and the power battery.

[0011] The AC charging pile charges and maintains the power battery through the high-voltage circuit, and the low-voltage circuit is configured to control and monitor the charging and maintaining process of the power battery.

[0012] In summary, the power battery maintenance device provided by the present application can form a low-voltage circuit and a high-voltage circuit after being connected with a power battery and an AC battery. The device uses the high-voltage circuit to charge, uses the DC-DC converter in the low-voltage circuit to generate a low-voltage DC power source, and provides low-voltage power for the controller, the on-board charger and the power battery. Each module in the low-voltage circuit controls and monitors the charging process to ensure the safety of the charging and maintaining process. Since only the operator needs to connect the device, the power battery and the AC charging pile, the operation is very simple, and professional personnel are not required to charge, discharge and balance the power battery for maintenance, nor is it necessary to maintain the power battery at the supplier. Therefore, the device is suitable for popularization and use. Moreover, since the device can form a low-voltage circuit to provide low-voltage power for the power battery, the power battery can be mounted on a vehicle or not, unlike the prior art which requires the power battery to be mounted for maintenance. Therefore, the maintenance work is very simple and easy to implement. In addition, the device is suitable for AC charging piles, and therefore has strong applicability due to the wide coverage of AC charging piles. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A schematic diagram of a high-voltage circuit formed by the power battery maintenance device and the power battery according to an embodiment of the present application is provided;

[0014] Figure 2 A schematic diagram of a low-voltage circuit formed by the power battery maintenance device and the power battery according to an embodiment of the present application is provided;

[0015] Figure 3 A specific connection schematic diagram of a low-voltage circuit formed by the power battery maintenance device and the power battery according to an embodiment of the present application is provided. DETAILED DESCRIPTION

[0016] The application will be described in further detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that only parts related to the application are shown in the drawings for ease of description.

[0017] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and embodiments.

[0018] In a first aspect, the embodiments of the present application provide a power battery maintenance device.

[0019] Referring to Figure 1 and Figure 2 , the maintenance device includes an on-board charger, a DC-DC converter, a controller, and a slow charging socket for connecting an alternating current charging pile, and a high-voltage loop and a low-voltage loop can be formed between the power battery and the maintenance device, wherein:

[0020] The slow charging socket and the high-voltage interface of the on-board charger are interconnected, and the on-board charger, the DC-DC converter, and the high-voltage interface of the power battery are interconnected to form the high-voltage loop; the slow charging socket and the low-voltage interface of the on-board charger are interconnected, and the on-board charger, the controller, the DC-DC converter, and the low-voltage interface of the power battery are interconnected to form the low-voltage loop;

[0021] In the high-voltage loop, the on-board charger is configured to convert the high-voltage alternating current source delivered by the alternating current charging pile through the slow charging socket into a high-voltage direct current source, and supply the high-voltage direct current source to the DC-DC converter and the power battery; in the low-voltage loop, the DC-DC converter is configured to convert the high-voltage direct current source into a low-voltage direct current source, so that the low-voltage direct current source powers the DC-DC converter, the controller, the on-board charger, and the power battery;

[0022] The alternating current charging pile charges and maintains the power battery through the high-voltage loop, and the low-voltage loop is used for controlling and monitoring the charging and maintaining process of the power battery.

[0023] It can be understood that the function of the slow charging socket is to connect the alternating current charging pile and receive the high-voltage alternating current source output by the alternating current charging pile.

[0024] (1) For the high-voltage loop:

[0025] Referring to Figure 1, OBC is a vehicle charger, DC / DC is a DC-DC converter, three high-voltage interfaces L1, L2, and L3 of the slow charging socket and three high-voltage interfaces L1, L2, and L3 of the vehicle charger are connected one by one, specifically through a high-voltage wire harness. L1, L2, and L3 refer to the ports of three-phase alternating current, that is, three-phase alternating current output by the charging pile is input to the three high-voltage interfaces L1, L2, and L3 of the vehicle charger through the three high-voltage interfaces L1, L2, and L3 of the slow charging socket. The vehicle charger converts the three-phase alternating current into a high-voltage direct current source, and then inputs a part of the high-voltage direct current source to the high-voltage interface of the DC-DC converter, and inputs the remaining part to the high-voltage interfaces of the power battery, that is, the DC+ interface and the DC- interface, to charge the power battery. Among them, the high-voltage interfaces between the vehicle charger and the power battery are connected through a high-voltage wire harness, and the high-voltage interface of the DC-DC converter is connected on the high-voltage wire harness between the vehicle charger and the power battery through a high-voltage wire harness, thereby realizing the high-voltage interconnection between the power battery, the vehicle charger, and the DC-DC converter. The above part forms the high-voltage loop.

[0026] (2) For the low-voltage loop:

[0027] Referring to Figure 2 and 3 , the low-voltage interfaces of the slow charging socket, that is, the CC interface, the CP interface, and the PE interface, are connected one by one with the low-voltage interfaces of the vehicle charger, that is, the CC interface, the CP interface, and the PE interface, through a low-voltage wire harness. The CC interface refers to the vehicle connection confirmation interface, and the vehicle connection confirmation signal is transmitted through the interface. The CP interface refers to the charging pile connection confirmation interface, and the charging pile connection confirmation signal is transmitted through the interface. PE is the full name of protective earthing conductor port in English, so the PE interface can also be called the protective conductor interface, which is an interface for protection, grounding, and discharge.

[0028] Moreover, the multiple low-voltage interfaces of the vehicle charger and the respective low-voltage interfaces of the power battery are connected one by one through a low-voltage wire harness, and the multiple low-voltage interfaces of the DC-DC converter are connected one by one on the corresponding low-voltage wire harness between the vehicle charger and the power battery through a low-voltage wire harness, and the multiple low-voltage interfaces of the controller are connected one by one on the corresponding low-voltage wire harness between the vehicle charger and the power battery through a low-voltage wire harness, thereby realizing the low-voltage interconnection between the vehicle charger, the controller, the DC-DC converter, and the power battery.

[0029] The plurality of low-voltage interfaces interconnecting between the on-board charger and the power battery include a CAN_H interface, a CAN_L interface, a constant power + interface, a constant power - interface, and a hard-wire wake-up interface; and the CAN_H interface, the CAN_L interface, the constant power + interface, the constant power - interface, and the hard-wire wake-up interface of the DC-DC converter and the controller are respectively connected to the corresponding low-voltage harness between the on-board charger and the power battery. The CAN_H interface and the CAN_L interface are transmission interfaces for interactive information, the constant power + interface and the constant power - interface are low-voltage electrical interfaces, and low-voltage electricity is transmitted through the constant power + interface and the constant power - interface after power-on. During the charging process, each module needs to be in a continuous wake-up state, and the hard-wire signal for continuously waking up each module is transmitted through the hard-wire wake-up interface.

[0030] In addition, referring to Figure 3 , after the on-board charger is woken up by the CC signal or the CP signal or other signals, the on-board charger will first wake up the controller, and the controller wakes up the power battery, the DC-DC converter, etc. through the hard-wire wake-up interface. The on-board charger also has a hard-wire wake-up controller interface, and the controller also has an OBC hard-wire wake-up interface. The signal for waking up the controller by the on-board charger is transmitted to the OBC hard-wire wake-up interface through the hard-wire wake-up controller interface, and then the controller is woken up.

[0031] Through the connection of the above-mentioned low-voltage interfaces, the low-voltage loop is formed.

[0032] The DC-DC converter converts the high-voltage direct current source into a low-voltage direct current source, and then supplies power to the controller, the on-board charger, and the power battery. The power supply here is low-voltage power supply. First, each module is powered on at low voltage, then some logical judgment is performed, and high-voltage power-on is performed after meeting the requirements of high-voltage power-on, and then charging is performed. The low-voltage direct current source can be 12V.

[0033] It can be seen that the AC charging pile can charge and maintain the power battery through the high-voltage loop, and the functions of each module in the low-voltage loop are to control and monitor before and during charging to ensure smooth charging and safety during charging, thereby providing protection for charging and maintenance.

[0034] In one embodiment, the maintenance device can further include:

[0035] A low-voltage direct current battery is connected in the low-voltage loop and is used to supply power to the DC-DC converter, the controller, the on-board charger, and the power battery before the low-voltage direct current source supplies power to the controller, the on-board charger, and the power battery.

[0036] It can be understood that the on-board charger converts the high-voltage alternating current source into a high-voltage direct current source, and then provides the high-voltage direct current source to the DC-DC converter, and the DC-DC converter converts the high-voltage direct current source into a low-voltage direct current source to supply power to the on-board charger, the controller and the power battery. However, before this, the on-board charger, the controller and the power battery need to be powered by a low-voltage direct current battery, at this time, the low-voltage direct current battery is discharged. Referring to Figure 3 , the low-voltage direct current battery is a 12V battery to ensure that the on-board charger, the controller and the power battery are always powered by low-voltage. After the DC-DC converter outputs a low-voltage direct current source to supply power to the on-board charger, the controller and the power battery, the low-voltage direct current battery is charged.

[0037] In an embodiment, in the low-voltage loop, the on-board charger can be configured to: after receiving a wake-up signal, initialize, after initialization, determine whether a vehicle connection confirmation signal is valid and whether a charging pile connection confirmation signal is valid; if the vehicle connection confirmation signal is valid and the charging pile connection confirmation signal is valid, send a hard-wire signal to the controller, and control a first switch to be closed to make the alternating current charging pile know that the new energy vehicle is ready;

[0038] The controller is configured to: after receiving the hard-wire signal sent by the on-board charger, initialize to wake up the controller; after initialization, send a hard-wire signal to the power battery and the DC-DC converter, respectively;

[0039] The power battery is configured to: after receiving the hard-wire signal sent by the controller, initialize to wake up the power battery;

[0040] The DC-DC converter is configured to: after receiving the hard-wire signal sent by the controller, initialize to wake up the DC-DC converter.

[0041] For example, in an actual scenario, an operator connects the maintenance device, the power battery and the alternating current charging pile provided by the embodiment of the application to form the high-voltage loop and the low-voltage loop. Then, the switch of the 12V battery is closed, and the 12V battery provides low-voltage power.

[0042] Then, the operator completes the plug-in action through the slow charging gun of the alternating current charging pile, at this time, the vehicle-mounted controller can receive the CC signal, i.e., the vehicle connection confirmation signal from the slow charging socket. After receiving the CC signal, the vehicle-mounted controller is initialized, the initialization process is the wake-up process, and after the initialization is completed, the vehicle-mounted controller is woken up. Then, it is judged whether the CC signal is valid, and after the CC signal is valid, the CP signal is received. When the operator swipes the card, the vehicle-mounted charger can receive the CP signal, i.e., the charging pile connection confirmation signal. If the CP signal is received within five minutes of receiving the CC signal, and the duty cycle of the CP signal is within 8% to 97%, the voltage of the CP signal is greater than 3.3V, and the frequency of the CP signal is within the range of 500HZ to 1500HZ, then the CP signal is valid. It can be seen that at this time, both the CP signal and the CC signal are valid, so the vehicle-mounted charger sends a hard-wire signal to the controller, which is used to wake up the controller, and then the vehicle-mounted controller controls the first switch to be closed. After the first switch is closed, the voltage detected by the alternating current charging pile decreases from 9V to 6V, so that the alternating current charging pile knows that the new energy vehicle is ready. The vehicle-mounted charger sends the hard-wire signal to the OBC hard-wire wake-up interface of the controller through the hard-wire wake-up controller interface.

[0043] Of course, if the CC signal is invalid, the vehicle-mounted controller enters sleep and will not perform subsequent steps. If the CP signal is invalid, the vehicle-mounted controller enters sleep and will not perform subsequent steps.

[0044] Then, after the controller receives the hard-wire signal sent by the vehicle-mounted controller, it is initialized, i.e., woken up, and after the initialization is completed, the wake-up of the controller is realized. Then, the controller sends a hard-wire signal to the power battery and the DC-DC converter. After the power battery receives the hard-wire signal, it is initialized, and after the initialization is completed, the power battery is woken up. After the DC-DC converter receives the hard-wire signal, it is initialized, and after the initialization is completed, the DC-DC converter is woken up.

[0045] It can be seen that through the above process, the wake-up of the vehicle-mounted charger, the controller and the DC-DC converter in the device, and the wake-up of the power battery can be realized.

[0046] After the wake-up of each module, some preparations are needed before charging, such as the judgment of the high-voltage power-on condition by the controller, the judgment of the maintenance condition by the power battery, the judgment of the start condition by the DC-DC converter, etc.

[0047] In an embodiment, the vehicle-mounted charger can also be used to send a signal to the controller that the working state is waiting.

[0048] The controller can also be used to send a signal to the power battery that the battery maintenance mode is alternating current charging after the initialization is completed.

[0049] The power battery can be configured to: if a signal of a battery maintenance mode being AC charging sent by the controller is received, judge whether the power battery meets a maintenance condition after initialization is completed; and if the maintenance condition is met, send a signal of a high-voltage power-on request being requested to the controller.

[0050] The DC-DC converter can be configured to: send a signal of a working state being waiting to the controller after initialization is completed.

[0051] The controller can be further configured to: after receiving a signal of a working state being waiting sent by the on-board charger, a signal of a working state being waiting sent by the DC-DC converter and a signal of a high-voltage power-on request being requested sent by the power battery, send an instruction of starting high-voltage power-on to the power battery.

[0052] The power battery can be further configured to: perform a high-voltage power-on operation after receiving the instruction of starting high-voltage power-on sent by the controller, and send a signal of high-voltage power-on completion to the controller after the high-voltage power-on operation is completed.

[0053] The maintenance condition can include that the power battery has no high-voltage power-on fault, a minimum temperature of the power battery is greater than a preset low temperature value, a maximum temperature of the power battery is less than a preset high temperature value and a remaining capacity of the power battery is less than a preset capacity. For example, the preset low temperature value is -20°, the preset high temperature value is 55° and the preset capacity is 97%.

[0054] That is to say, after the controller is initialized, in addition to sending a hard-wired signal to the power battery and the DC-DC converter, the controller also sends a signal of a battery maintenance mode being AC charging to the power battery, so as to inform the power battery to use AC charging for charging maintenance. When the power battery receives the signal of the battery maintenance mode being AC charging, the power battery judges the maintenance condition. If the power battery meets the maintenance condition at this time, the power battery sends a signal of a high-voltage power-on request being requested to the controller.

[0055] Further, the on-board charger will send a signal of working state as standby to the controller after closing the first switch. The DC-DC converter will also send a signal of working state as standby to the controller after initialization. Thus, the controller will receive the signal of working state as standby from the on-board charger, the signal of working state as standby from the DC-DC converter and the signal of high voltage power-up request as request from the power battery. When the controller receives the three signals, it will consider that the high voltage power-up condition is met, and thus send an instruction of opening high voltage power-up to the power battery. When the power battery receives the instruction of opening high voltage power-up, it will perform high voltage power-up operation, for example, close the pre-charging relay, the main negative relay and the main positive relay in sequence, and open the pre-charging relay when the voltage meets the requirement. When the power battery completes the high voltage power-up operation, it will send a signal of high voltage power-up completion to the controller, so that the controller knows that the high voltage power-up has been completed, and a very important preparation work is completed.

[0056] In the signal of working state as standby, the standby means standby. In the instruction of opening high voltage power-up, the high voltage power-up instruction = ON.

[0057] Of course, if the controller can send the hard-wired signal and the signal of battery maintenance mode as AC charging for multiple times within 5 minutes until it receives the signal of working state as standby from the on-board charger, the signal of working state as standby from the DC-DC converter and the signal of high voltage power-up request as request from the power battery. If the three signals are not received after 5 minutes, it will be considered that the high voltage power-up condition is not met, and thus stop maintaining wake-up by the hard-wired signal and enter sleep.

[0058] After the controller knows that the high voltage power-up is completed, it can control the DC-DC converter to enter working state. The DC-DC converter in working state can convert the high voltage direct current source into low voltage direct current source, of course, on the premise that the on-board charger outputs current and voltage, but at this time, the on-board charger has not output power and voltage, i.e. has not output high voltage direct current source.

[0059] In an embodiment, the controller can also be configured to send an enable signal of opening working to the DC-DC converter after receiving the signal of high voltage power-up completion fed back by the power battery. Correspondingly, the DC-DC converter can also be configured to enter working state and feed back a signal of working state as working to the controller if the DC-DC converter has no fault after receiving the enable signal of opening working sent by the controller.

[0060] That is, the controller sends an enable signal to the DC-DC converter after learning that the high-voltage power-on is completed, i.e., the working enable signal = ON. When the DC-DC converter receives the enable signal, it judges whether there is a fault. If there is no fault, the DC-DC converter enters the working state and sends a signal to the controller that the working state = working.

[0061] It can be seen that the condition for the DC-DC converter to enter the working state is that the DC-DC converter receives the enable signal and has no fault.

[0062] When the controller receives the signal that the working state = working from the DC-DC converter, it is learned that the DC-DC converter enters the working state. The controller can send the enable signal multiple times within 5 seconds until it receives the signal that the working state = working. However, if the signal that the working state = working is not received within 5 seconds after the first sending of the enable signal, the controller sends an disable signal to the DC-DC converter, i.e., the working enable signal = OFF, so that the DC-DC converter does not need to enter the working state.

[0063] It can be seen that the DC-DC converter enters the working state through the above process.

[0064] In addition to making the DC-DC converter enter the working state, the power battery and the on-board charger also need to enter the working state.

[0065] In an embodiment, the power battery can also be configured to send an enable signal and charging demand information to the on-board charger. The enable signal is in a constant current mode or a constant voltage mode, and the charging demand information includes a charging demand current and a charging demand voltage.

[0066] The on-board charger can also be configured to, when receiving the enable signal and the charging demand information, calculate an output current and an output voltage of the on-board charger according to the charging demand information, perform the output of the output current and the output voltage according to the enable signal, charge the power battery, and feed back a signal that the working state = working to the power battery.

[0067] The power battery can also be used to detect whether the actual charging current of the power battery is less than 0, and if so, receive the charging of the vehicle charger; when the power battery is charged to a remaining capacity reaching a preset value, the voltages of each cell are obtained, the cell with a higher voltage is selected, the charging current of the power battery is reduced to below a preset current value, and the equalization state is started, and in the equalization state, the cell with a higher voltage is connected to a parallel resistor so as to make the cell with a higher voltage not be charged, and the remaining cells continue to be charged.

[0068] The output current and output voltage of the vehicle charger supply the remaining current and remaining voltage of the DC-DC converter, and the remaining current and remaining voltage supply the charging current and charging voltage to the power battery.

[0069] That is, when the power battery sends a high-voltage power-on completion signal to the controller, an enable signal and charging demand information are also sent to the vehicle charger. The enable signal is a constant current mode or a constant voltage mode, that is, the vehicle charger is informed by the enable signal to adopt which mode for charging. The charging demand information includes a charging demand current and a charging demand voltage.

[0070] When the vehicle charger receives the enable signal and the charging demand information, the output current and the output voltage of the vehicle charger are calculated according to the charging demand information, and the output of the output current and the output voltage is performed according to the enable signal, so as to charge the power battery and feed back a signal of a working state to the power battery.

[0071] Specifically, the vehicle charger selects the smallest current value as the output current from a plurality of current values, the plurality of current values including the charging demand current, a power value obtained by looking up a table according to the current temperature and the current remaining capacity of the power battery, and the maximum bearing current (usually 20A) of the external cable, wherein the table refers to a data table reflecting the charging capacity of the power battery, and the data table includes current values corresponding to different temperatures and different remaining capacities. The output voltage is the charging demand voltage in the charging demand information. When the equalization is started, the maximum current (usually 3A) of the equalization start needs to be considered in determining the output current.

[0072] When the vehicle charger calculates the output current and the output voltage, if the received enable signal is the constant current mode, the output of the high-voltage direct current source is performed according to the output current. If the received enable signal is the constant voltage mode, the output of the high-voltage direct current source is performed according to the output voltage.

[0073] The high-voltage DC source output by the on-board charger is first supplied to the DC-DC converter. Since the DC-DC converter is already in working state at this time, the received high-voltage DC source can be converted into a low-voltage DC source, which in turn powers the controller, the power battery and the on-board controller, i.e. the 12V battery is no longer needed to supply power and is converted from a discharging state to a charging state.

[0074] Then, the remaining high-voltage DC source after the high-voltage DC source output by the on-board charger is supplied to the DC-DC converter is supplied to the power battery, and the on-board charger also sends a signal to the power battery indicating that the working state is in working, so as to inform the power battery that the on-board charger has currently provided a high-voltage DC source. The power battery determines whether the actual charging current is valid. Since the charging current is negative, the actual charging current is valid if it is less than 0. Therefore, the high-voltage interface of the power battery receives the above-mentioned remaining high-voltage DC source and charges.

[0075] Since there are differences in the voltages of the individual cells of the power battery, the equalization state can be started when charging to a certain extent. For example, when the power battery is charged to 98%, there is still 2% of the remaining capacity to be full. At this time, the power battery obtains the voltages of the individual cells, so as to know which cells have higher voltages and which cells have lower voltages. A resistor is connected in parallel in advance on each cell, and a switch is arranged in the branch where the parallel resistor is located, and the switch is used to control whether the parallel resistor is connected to the circuit. When the equalization state is not started, the switch on the cell is open, and the cell is not connected to the parallel resistor, and at this time the cell can be normally charged.

[0076] When the power battery is charged to 98%, the charging current is reduced to below the preset current value, so that the charging current meets the equalization starting condition. Then the equalization state is started for the cells with higher voltages, i.e. the switch of the cell with higher voltage is closed, so that the cell with higher voltage is connected to the parallel resistor, so that the charging current enters the parallel resistor and does not charge the cell with higher voltage. The switch of the cell with lower voltage is still open and is not connected to the parallel resistor, so that the cell with lower voltage is normally charged. In this way, the voltage difference between the individual cells gradually decreases. When the power battery is charged to 100%, the voltage difference between the individual cells is balanced.

[0077] The charging mode can change, for example, the enable signal is in constant current mode at the beginning, and changes to constant voltage mode when charging to a certain stage.

[0078] If the whole charging process is in constant current mode, when charging to 98%, the voltage of each battery cell is obtained to know which battery cell has higher voltage and which battery cell has lower voltage. Then the charging current is reduced to below 3A, and the battery cell with higher voltage is started in the equalization state. After 10 minutes of equalization, the charging is completed. Through the 10 minutes of equalization, the voltage difference between the battery cells is reduced.

[0079] If the constant current mode is started, when charging to 98%, the charging current is reduced to below 3A, and the constant voltage mode is changed. Since the voltage is constant in the constant voltage mode, the charging current gradually decreases during the charging process, for example, to 2A, 1.5A, 1A. The charging is slow, and therefore it may take 30 minutes to be fully charged. Therefore, the equalization state is started for 30 minutes, and the voltage difference between the battery cells is smaller.

[0080] It can be seen that during the charging process, not only the charging maintenance is realized, but also the equalization maintenance is realized.

[0081] In an embodiment, the controller can be further configured to determine whether a first end condition is reached, and if the first end condition is reached, send an enable signal for stopping working to the DC-DC converter.

[0082] The DC-DC converter can be further configured to stop working if the enable signal for stopping working sent by the controller is received or a fault occurs in the DC-DC converter, send a signal for working state being error waiting to the controller, and enter hibernation.

[0083] The controller can be further configured to send an instruction for stopping high-voltage power-on to the power battery when the signal for working state being error waiting sent by the DC-DC converter is received, stop sending a hard-wire signal for maintaining wake-up to the power battery, the DC-DC converter and the on-board charger after a signal for high-voltage power-off completion fed back by the power battery is received, and enter hibernation.

[0084] That is, the controller determines whether a first end condition is reached. If the first end condition is reached, the controller sends an enable signal for stopping working to the DC-DC converter, i.e., the working enable signal = OFF. When the DC-DC converter receives the enable signal for stopping working, it stops working, sends a signal for working state being error waiting to the controller, i.e., the signal for working state = standby / fault, and then enters hibernation. Of course, if a fault occurs in the DC-DC converter during working, the DC-DC converter stops working, sends a signal for working state being error waiting to the controller, and then enters hibernation.

[0085] As can be seen, there are two conditions for the DC-DC converter to end the work: one is that the DC-DC converter fails, and the other is that the controller receives the signal of the work state being error waiting sent by the DC-DC converter. The two conditions are in an "or" relationship.

[0086] In practice, the controller can send the enable signal of the work being closed to the DC-DC converter for multiple times within a certain time (for example, 5 seconds) until the signal of the work state being error waiting sent by the DC-DC converter is received. However, if the signal of the work state being error waiting sent by the DC-DC converter is not received within a certain time after the enable signal of the work being closed is sent for the first time, the controller will send the instruction of the high-voltage power-on being closed to the power battery.

[0087] When the controller receives the signal of the work state being error waiting sent by the DC-DC converter, the instruction of the high-voltage power-on being closed is sent to the power battery, that is, the high-voltage power-on instruction = OFF. When the power battery receives the instruction of the high-voltage power-on being closed sent by the controller, the low-voltage operation is performed, and the signal of the high-voltage power-off completion is sent to the controller after the low-voltage operation is completed. If the controller receives the signal of the high-voltage power-off completion within a certain time, the hard-wire signal of maintaining the wake-up is stopped from being sent to the power battery, the DC-DC converter and the on-board charger, that is, the power battery, the DC-DC converter and the on-board charger are continuously woken up, and finally the controller enters the sleep state.

[0088] Of course, if the controller does not receive the signal of the high-voltage power-off completion sent by the power battery within a certain time (for example, within 30 seconds) after the instruction of the high-voltage power-on being closed is sent, it may be because the power battery has completed a series of actions and entered the sleep state, or it may be because the signal transmission is wrong. At this time, the controller also stops sending the hard-wire signal of maintaining the wake-up to the power battery, the DC-DC converter and the on-board charger, and enters the sleep state. As can be seen, by setting a time limit, the controller is prevented from waiting endlessly.

[0089] In an embodiment, the first end condition can include at least one of the following: communication timeout, the hard-wire signal of maintaining the wake-up sent by the on-board charger being invalid, and the high-voltage power-on request sent by the power battery being no request. The four conditions are in an "or" relationship.

[0090] As can be seen, when the communication timeout, the hard-wire signal of maintaining the wake-up sent by the on-board charger being invalid, or the high-voltage power-on request sent by the power battery being no request occurs, the first end condition is met.

[0091] At this time, the controller and the DC-DC converter end the work and enter the sleep state.

[0092] In one embodiment, the power battery can also be used to determine whether a second end condition is reached, and if the second end condition is reached, send a signal of 0 to the vehicle-mounted charger for enabling signal of closing work and charging demand information, and send a signal of no request to the controller for high voltage power-on request; after receiving the instruction of closing high voltage power-on sent by the controller, perform a low voltage operation, send a signal of low voltage power-off completion to the controller after the low voltage operation is completed, and enter hibernation;

[0093] The second end condition includes at least one of the following:

[0094] The instruction of closing high voltage power-on sent by the controller, reaching a charging cutoff condition, the power battery having a low voltage power-off fault, the minimum temperature of the power battery being less than or equal to a preset low temperature value, the maximum temperature of the power battery being greater than or equal to a preset high temperature value, and communication timeout.

[0095] That is, when the power battery determines that the second end condition is reached, it also sends a signal of enabling signal of closing work, i.e., work enabling signal = OFF, to the vehicle-mounted charger, and sends a signal of charging demand information of 0, i.e., charging demand current and charging demand voltage of 0, to the vehicle-mounted charger, and sends a signal of no request for high voltage power-on request to the controller. The signal of enabling signal of closing work and the signal of charging demand information of 0 can both be used as a judgment condition for the vehicle-mounted charger to end work. The signal of no request for high voltage power-on request can be used as a judgment condition for the controller to end work.

[0096] When the power battery receives the instruction of closing high voltage power-on, it performs a low voltage operation, for example, sequentially disconnects the main positive relay and the main negative relay. After the low voltage operation is completed, a signal of low voltage power-off completion is sent to the controller, and then hibernation can be entered.

[0097] In the second end condition, the instruction of closing high voltage power-on sent by the controller, i.e., high voltage power-on instruction = OFF, the charging cutoff condition, i.e., charging reaching 100%, the power battery having a low voltage power-off fault, the minimum temperature of the power battery being less than or equal to a preset low temperature value, the maximum temperature of the power battery being greater than or equal to a preset high temperature value, and communication timeout, have an “or” relationship.

[0098] At this point, the power battery ends work and enters hibernation.

[0099] In one embodiment, the vehicle-mounted charger can also be used to determine whether a third end condition is reached, and if the third end condition is reached, stop outputting the output current and the output voltage, control the first switch to be closed, and stop sending a hard-wire signal for maintaining wake-up to the controller. The third end condition includes at least one of the following:

[0100] The vehicle connection confirmation signal is invalid, the charging pile connection confirmation signal is invalid, the enable signal sent by the power battery to close the work, the charging demand information sent by the power battery is 0, communication timeout and the vehicle charger occurs an unchargeable fault.

[0101] That is, when the vehicle charger judges to meet the third ending condition, it stops outputting current and voltage, that is, stops charging the power battery, and disconnects the first switch, so that the AC charging pile knows that the new energy vehicle has stopped charging, and also sends a hard line signal to the controller to stop maintaining wake-up. This makes the hard line signal sent by the vehicle charger to the controller to maintain the wake-up of the controller invalid, thus meeting one of the above first ending conditions.

[0102] Of course, in addition to stopping sending the hard line signal to maintain wake-up to the controller, a signal with a working state of waiting for an error can also be sent to the controller to inform the controller to end work.

[0103] Among them, the vehicle connection confirmation signal is invalid, the charging pile connection confirmation signal is invalid, the enable signal sent by the power battery to close the work, the charging demand information sent by the power battery is 0, communication timeout and the vehicle charger occurs an unchargeable fault, and the six third ending conditions are in an "or" relationship.

[0104] At this point, the vehicle charger ends work and enters sleep.

[0105] It can be understood that there is no sequence between the judgment of the first ending condition by the controller, the judgment of the second ending condition by the power battery and the judgment of the third ending condition by the vehicle charger. When any one of the three modules meets one of the ending conditions, it will enter the work ending process, thereby affecting the other modules to also end work, and finally all the modules enter sleep.

[0106] Among them, the 12V battery can also be replaced with a 24V battery, but at this time the low-voltage DC source required by other modules such as the vehicle charger, the power battery, the controller and the DC-DC converter also needs to be adapted to 24V.

[0107] It can be understood that the power battery is mainly responsible for performing high-voltage on / off actions, controlling the vehicle-mounted charger to work, high-voltage safety detection, self-charging / maintenance requirement detection, active / passive balancing functions, etc. The controller is mainly responsible for controlling the high-voltage on / off, controlling the DC-DC converter to work, receiving the hard-wired signal of the vehicle-mounted charger to be woken up, and controlling the hard-wired wake-up of other modules. The DC-DC converter is mainly responsible for converting the high-voltage DC source into a low-voltage DC source. The vehicle-mounted charger is mainly responsible for converting the high-voltage AC source into a high-voltage DC source, calculating and controlling the output current and output voltage.

[0108] In summary, the power battery maintenance device proposed in the present application can form a low-voltage loop and a high-voltage loop after being connected with the power battery and the alternating current battery, charges using the high-voltage loop, generates a low-voltage DC source using the DC-DC converter in the low-voltage loop, and provides low-voltage power for the controller, the vehicle-mounted charger, and the power battery. Each module in the low-voltage loop controls and monitors the charging process to ensure the safety of the charging maintenance process. Since only the operator needs to connect the device, the power battery, and the alternating current charging pile, the operation is very simple, and professional personnel are not required to charge and discharge and balance the power battery for maintenance, nor is it necessary to maintain at the power battery supplier. It can be seen that it is very suitable for popularization and use. Moreover, since the device can form a low-voltage loop to provide low-voltage power for the power battery, the power battery can be mounted on the whole vehicle or not mounted on the whole vehicle, and it is not necessary to mount the power battery for maintenance as in the prior art. It can be seen that the maintenance work is very simple and easy to implement. In addition, the device is suitable for alternating current charging piles, and since the coverage of alternating current charging piles is wide, the device has strong applicability.

[0109] The principles and implementation modes of the present application are described by applying specific examples in this paper, and the above examples are only used to help understand the method and its core idea. The above description is only the preferred embodiment of the present application. It should be noted that due to the limited nature of the language expression, there are objectively infinite specific structures, and for ordinary technical personnel in this technical field, some improvements, refinements, or changes can be made without departing from the principles of the present application, and the above technical features can be combined in an appropriate manner. These improvements, refinements, changes, or combinations, or the application of the inventive concept and technical solution to other occasions without improvement, shall be regarded as the protection scope of the present application.

Claims

1. A power cell maintenance device, characterized by, The maintenance device comprises an on-board charger, a DC-DC converter, a controller and a slow charging socket for connecting an alternating current charging pile, and a high-voltage loop and a low-voltage loop can be formed between the power battery and the maintenance device, wherein: The slow charging socket and the high-voltage interface of the on-board charger are interconnected, and the high-voltage interfaces of the on-board charger, the DC-DC converter and the power battery are interconnected to form the high-voltage loop; the slow charging socket and the low-voltage interface of the on-board charger are interconnected, and the low-voltage interfaces of the on-board charger, the controller, the DC-DC converter and the power battery are interconnected to form the low-voltage loop; In the high-voltage loop, the on-board charger is configured to convert a high-voltage alternating current source delivered by the alternating current charging pile through the slow charging socket into a high-voltage direct current source and supply the high-voltage direct current source to the DC-DC converter and the power battery; in the low-voltage loop, the DC-DC converter is configured to convert the high-voltage direct current source into a low-voltage direct current source to supply the low-voltage direct current source to the DC-DC converter, the controller, the on-board charger and the power battery; The alternating current charging pile charges and maintains the power battery through the high-voltage loop, and the low-voltage loop is configured to control and monitor the charging and maintaining process of the power battery; whether the actual charging current of the power battery is less than 0 is detected, and if so, the charging of the on-board charger is received; when the power battery is charged to a remaining capacity reaching a preset value, the voltages of each cell are obtained, the cell with a higher voltage is selected, the charging current of the power battery is reduced to below a preset current value, and an equalization state is started, in which the cell with a higher voltage is connected to a parallel resistor so as to not be charged, and the remaining cells continue to be charged; The output current and output voltage of the on-board charger supply the remaining current and remaining voltage of the DC-DC converter, and the remaining current and remaining voltage supply the power battery as charging current and charging voltage.

2. The apparatus of claim 1, wherein, The maintenance device further comprises: A low-voltage direct current battery connected in the low-voltage loop and configured to supply the DC-DC converter, the controller, the on-board charger and the power battery before the low-voltage direct current source supplies the controller, the on-board charger and the power battery.

3. The device of claim 1, wherein In the low-voltage loop, the on-board charger is configured to initialize after receiving a wake-up signal, and to determine whether a vehicle connection confirmation signal and a charging pile connection confirmation signal are valid after the initialization is completed; if the vehicle connection confirmation signal is valid and the charging pile connection confirmation signal is valid, the on-board charger is configured to send a hard-wire signal to the controller and control a first switch to be closed so that the alternating current charging pile knows that the new energy vehicle is ready. The controller is configured to: initialize after receiving the hard-wire signal sent by the on-board charger to realize wake-up of the controller; and send a hard-wire signal to the power battery and the DC-DC converter respectively after initialization is completed; The power battery is configured to: initialize after receiving the hard-wire signal sent by the controller to realize wake-up of the power battery; The DC-DC converter is configured to: initialize after receiving the hard-wire signal sent by the controller to realize wake-up of the DC-DC converter.

4. The apparatus of claim 3, wherein The on-board charger is further configured to: send a signal of a working state being standby to the controller; The controller is further configured to: send a signal of a battery maintenance mode being AC charging to the power battery after initialization is completed; The power battery is configured to: if the signal of the battery maintenance mode being AC charging sent by the controller is received, judge whether the power battery meets a maintenance condition after initialization is completed; and if the maintenance condition is met, send a signal of a high-voltage power-on request being a request to the controller; The DC-DC converter is configured to: send a signal of a working state being standby to the controller after initialization is completed; The controller is further configured to: send an instruction of starting high-voltage power-on to the power battery after receiving the signal of the working state being standby sent by the on-board charger, the signal of the working state being standby sent by the DC-DC converter and the signal of the high-voltage power-on request being a request sent by the power battery; The power battery is further configured to: perform a high-voltage power-on operation after receiving the instruction of starting high-voltage power-on sent by the controller, and send a signal of high-voltage power-on completion to the controller after the high-voltage power-on operation is completed; The maintenance condition includes that the power battery has no high-voltage power-on fault, a minimum temperature of the power battery is greater than a preset low temperature value, a maximum temperature of the power battery is less than a preset high temperature value and a remaining capacity of the power battery is less than a preset capacity.

5. The apparatus of claim 4, wherein The controller is further configured to: send an enable signal of starting work to the DC-DC converter after receiving the signal of high-voltage power-on completion fed back by the power battery; The DC-DC converter is configured to: if the DC-DC converter has no fault after receiving the enable signal of starting work sent by the controller, enter a working state and feed back a signal of a working state being working to the controller.

6. The apparatus of claim 5, wherein The power battery can be further configured to: send an enable signal and charging demand information to the on-board charger; wherein the enable signal is a constant current mode or a constant voltage mode, and the charging demand information includes a charging demand current and a charging demand voltage. The vehicle-mounted charger is further configured to: calculate an output current and an output voltage of the vehicle-mounted charger according to the charging demand information when the enable signal and the charging demand information are received; perform output of the output current and the output voltage according to the enable signal to charge the power battery; and feed back a signal of an operating state of the power battery as working to the power battery.

7. The apparatus of claim 6, wherein, the controller is further configured to: determine whether a first end condition is reached, and if the first end condition is reached, send an enable signal of shutting down the operation to the DC-DC converter; the DC-DC converter is configured to: if the enable signal of shutting down the operation sent by the controller is received or a fault occurs in the DC-DC converter, stop the operation, send a signal of an operating state of the DC-DC converter as error waiting to the controller, and enter hibernation; the controller is configured to: when the signal of the operating state of the DC-DC converter as error waiting is received, send an instruction of shutting down high-voltage power-on to the power battery, and after a signal of high-voltage power-off completion fed back by the power battery is received, stop sending the hard-wire signal of maintaining wake-up to the power battery, the DC-DC converter and the vehicle-mounted charger, and enter hibernation.

8. The apparatus of claim 7, wherein, The first end condition includes at least one of the following: communication timeout, the hard-wire signal of maintaining wake-up of the vehicle-mounted charger being invalid, and the high-voltage power-on request sent by the power battery being no request.

9. The apparatus of claim 7, wherein, the power battery is further configured to: determine whether a second end condition is reached, and if the second end condition is reached, send a signal of the enable signal of shutting down the operation and the charging demand information being 0 to the vehicle-mounted charger, and send a signal of the high-voltage power-on request being no request to the controller; after the instruction of shutting down high-voltage power-on sent by the controller is received, perform a high-voltage operation, and after the high-voltage operation is completed, send a signal of high-voltage power-off completion to the controller, and enter hibernation; The second end condition includes at least one of the following: the instruction of shutting down high-voltage power-on sent by the controller, a charging cutoff condition being reached, a low-voltage power-off fault occurring in the power battery, a minimum temperature of the power battery being less than or equal to a preset low temperature value, a maximum temperature of the power battery being greater than or equal to a preset high temperature value, and communication timeout.

10. The apparatus of claim 9, wherein, the vehicle-mounted charger is further configured to: determine whether a third end condition is reached, and if the third end condition is reached, stop the output of the output current and the output voltage, control the first switch to be closed, stop sending the hard-wire signal of maintaining wake-up to the controller, and enter hibernation; The third end condition includes at least one of the following: the vehicle connection confirmation signal being invalid, the charging pile connection confirmation signal being invalid, the enable signal of shutting down the operation sent by the power battery, the charging demand information sent by the power battery being 0, communication timeout, and an unchargeable fault occurring in the vehicle-mounted charger.

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