A BMS control method for low-speed vehicles

Abstract

The present invention discloses a BMS control method for low-speed vehicles, comprising the following steps: (1) power-on mode allocation; (2) if there is a charging wake-up signal, then enter the charging mode, wherein the charging mode includes a pure heating mode, a pure charging mode, a charging and adding mode, and a heat preservation mode. If there is no charging wake-up signal, then determine whether there is a key signal wake-up, if so, enter the discharge mode, if there is no key signal wake-up, enter the abnormal wake-up fault. The present invention modularizes the complex BMS control strategy; the logical relationship between the modules is clear; the modular control allocation greatly improves the scalability of the strategy; and the whole function of the low-speed vehicle BMS control including heating is satisfied.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery management systems for low-speed vehicles, and in particular to a BMS control method for low-speed vehicles. Background Art

[0002] At present, low-speed electric vehicles are developing rapidly and the market demand is huge. The trend of using lithium batteries is getting bigger and bigger. BMS, as the core controller of lithium batteries, plays a role in battery management and control.

[0003] In winter, the temperature is low and the low-temperature performance of power batteries is poor. In order to ensure the performance of the power batteries, a heating system is usually introduced during charging. However, traditional charging heating cannot keep the battery temperature within the appropriate range after full charging. Therefore, a control method that is safe, stable and heat-insulating is needed. Summary of the invention

[0004] The purpose of the present invention is to provide a BMS control method for low-speed vehicles. Under the premise of ensuring safety and reliability, the design is optimized, and the state boundaries of the BMS control are distinguished by using the classic state machine control method, and the process under each mode is optimized to achieve the stability and scalability of the control method. At the same time, a heat preservation function is added to enable the battery to continuously maintain a good working temperature and starting temperature in a low-temperature charging environment.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A BMS control method for a low-speed vehicle comprises the following steps:

[0007] (1) Power-on mode allocation: When the BMS is awakened by a hard-wired signal, it first performs a self-test. After the self-test is completed, it determines whether there is a charging wake-up signal;

[0008] (2) If there is a charging wake-up signal, the charging mode is entered, where the charging modes include pure heating mode, pure charging mode, charging and adding mode, and insulation mode. If there is no charging wake-up signal, it is determined whether there is a key signal wake-up. If so, the discharge mode is entered. If there is no key signal wake-up, the abnormal wake-up fault is entered;

[0009] (2a) After entering the charging mode, first determine whether the SOC is 100%. If so, reset it to 99%. Then determine whether the temperature is greater than 0 degrees. If it is greater than 0 degrees, enter the single cell temperature judgment I. If it is greater than the value of single cell temperature judgment I, enter the pure charging mode. Otherwise, enter the charging and adding mode. If it is less than 0 degrees, enter the single cell temperature judgment II. If it is greater than the value of single cell temperature judgment II, enter the pure heating mode. Otherwise, report a low temperature fault.

[0010] (3) Switching between charging and discharging modes: After entering charging mode, if the charging hard-line wake-up signal is detected to disappear, the charging power-down mode is entered. After the power-down state is completed, it is determined whether there is a key wake-up signal. If there is, the discharge mode is entered. If not, the sleep mode is entered.

[0011] (4) After entering the discharge mode, if the key signal disappears or the charging signal appears, the system enters the discharge power-down mode. After the discharge power-down mode is completed, it is determined whether the charging signal still exists. If it exists, the system enters the charging mode. If not, the system enters the sleep mode.

[0012] In step (2a), the value of temperature judgment I is 5 degrees, and the value of temperature judgment II is -35 degrees;

[0013] In pure heating mode, when the temperature of a single cell is heated to more than 5 degrees, it enters charging and heating mode;

[0014] When the temperature of the charging and heating mode is higher than 15 degrees, the pure charging mode is entered. When the SOC reaches 100 during heating, the heat preservation mode is entered.

[0015] In pure charging mode, when the temperature drops below 5 degrees during charging, it enters the charging and charging mode. When the SOC reaches 100 during charging, it enters the warm-keeping mode.

[0016] After entering the pure heating mode, first determine whether the main positive relay is closed. If not, proceed with the pre-charging process. If closed, directly send the charging request voltage, current and related status information defined in the pure heating mode. After sending, close the heating relay, delay 100ms to disconnect the main positive relay, start pure heating, and continue to determine whether the cell temperature is greater than 5 degrees. If it is greater than 5 degrees, enter the charging and adding mode. Otherwise, continue heating until the heating timeout fault is triggered.

[0017] Furthermore, after entering the charge-while-charging mode, first determine whether the main positive relay is closed. If not, go through the pre-charging process. If closed, directly send the charging request voltage, current and related status information defined in the charge-while-charging mode. After sending, close the heating relay, and send the changed charging request voltage and current defined in the mode again. Then continue to determine whether the single cell voltage reaches 3.65V. If it reaches 3.65V, set the SOC to 100, and then enter the insulation mode. Continue to determine whether the single cell minimum temperature is greater than 15 degrees. If it is greater than 15 degrees, disconnect the heating relay and enter the pure charging mode.

[0018] Furthermore, after entering the pure charging mode, first determine whether the main positive relay is closed. If not, go through the pre-charging process. If closed, directly send the voltage, current information and related status information requested by the pure charging mode. During this period, continue to determine whether the single cell voltage reaches 3.65V and the post-SOC is 100, and enter the insulation mode. Continue to determine whether the single cell temperature is less than 5 degrees. If it is less than 5 degrees, enter the charging and adding mode until either of the two triggers exit from the pure charging mode.

[0019] Furthermore, after entering the insulation mode, the charging request voltage, current and related status information defined in the insulation mode are directly sent, where the requested current is 0. At this time, it is determined whether the cell temperature is less than 15 degrees. If it is less than 15 degrees, the heating relay is closed, and the charging request voltage and current required for heating are requested. Then the main positive relay is disconnected and heating is started until the temperature is greater than 25 degrees. The requested current is restored to 0, the heating relay is disconnected, and pre-charging and power-on are started.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The complex BMS control strategy is modularly allocated; the logical relationship between the modules is clear; the modular control allocation greatly improves the scalability of the strategy; it meets all the functions of low-speed vehicle BMS control including heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A power-on mode allocation diagram of the present invention;

[0023] Figure 2 A charging mode allocation diagram of the present invention;

[0024] Figure 3 This is a pure charging mode diagram of the present invention;

[0025] Figure 4 This is a pure heating mode diagram of the present invention;

[0026] Figure 5 This is a diagram of a charging and adding mode of the present invention;

[0027] Figure 6 It is the heat preservation mode diagram of the present invention;

[0028] Figure 7 This is a diagram of the charging and discharging mode of the present invention;

[0029] Figure 8 This is a fault handling diagram of the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0031] Example 1, please refer to Figure 1 :

[0032] Power-on mode assignment:

[0033] 1. Power-on mode allocation: After the BMS is awakened by a hard-wire signal, it first performs a self-test. After the self-test is completed, it first determines whether there is a charging wake-up signal. If so, it enters the charging mode. If not, it then determines whether there is a key signal awakening. If so, it enters the discharge mode. If not, it enters the abnormal awakening fault;

[0034] 1.1 Switching between charging and discharging modes: After entering charging mode, if the charging hard line wake-up signal disappears, the charging power-off mode is entered. After the power-off state is completed, it is determined whether there is a key wake-up signal. If there is, the discharge mode is entered. If not, the sleep mode is entered. After entering discharging mode, if the key signal disappears or the charging signal appears, the discharge power-off mode is entered. After the discharge power-off mode is completed, it is determined whether the charging signal still exists. If it exists, the charging mode is entered. If not, the sleep mode is entered.

[0035] like Figure 2-8 As shown:

[0036] Charging mode allocation and sub-mode jump and process:

[0037] 2. Charging mode initialization allocation: Charging mode includes heating mode, pure charging mode, charging and adding mode, and warming mode. When entering the charging mode, first determine whether the SOC is 100%. If so, reset it to 99%, and then determine whether the temperature is greater than 0 degrees. If it is greater than 0 degrees, enter 2.1, if it is less than 0 degrees, enter 2.2;

[0038] 2.1 Continue to determine whether the cell temperature is greater than 5 degrees. If it is greater than 5 degrees, enter the pure charging mode. If it is less than 5 degrees, enter the charging and adding mode.

[0039] 2.2 Continue to determine whether the monomer temperature is greater than -35 degrees. If it is greater than -35 degrees, enter the line heating mode. If it is less than -35 degrees, report a low temperature fault.

[0040] 2.3 After initialization is completed, the jump method of the four sub-modes is as follows:

[0041] 2.3.1 Pure heating mode (2.4) When the temperature of a single cell is heated to more than 5 degrees, it enters the charging and heating mode (2.5);

[0042] 2.3.2 Charging and heating mode: when the temperature is heated to more than 15 degrees, it enters the pure charging mode (2.6). When the SOC becomes 100 during heating, it enters the warm-keeping mode (2.7);

[0043] 2.3.3 Pure charging mode During the charging process, when the temperature drops below 5 degrees, it enters the charging and adding mode. After the SOC becomes 100 during the charging process, it enters the insulation mode.

[0044] 2.4 Pure heating mode: After entering the pure heating mode, first determine whether the main positive relay is closed. If not, proceed with the pre-charging process. If closed, directly send the charging request voltage, current and related status information defined in the pure heating mode. After sending, close the heating relay, delay 100ms to disconnect the main positive relay, start pure heating, and continue to determine whether the cell temperature is greater than 5 degrees. If it is greater than 5 degrees, enter the charging and adding mode. Otherwise, continue heating until the heating timeout fault is triggered.

[0045] 2.5 Charge while adding mode: After entering the charge while adding mode, first determine whether the main positive relay is energized. If it is not closed, the pre-charging process will be carried out. If it is closed, directly send the charging request voltage, current and related status information defined in the charge while adding mode. After sending, close the heating relay and send the changed charging request voltage and current defined in the mode again. (After closing the heating relay, the voltage and current of the charging request are different from when it is not closed, so the requested voltage and current must be changed again). At this time, continue to determine whether the single cell voltage reaches 3.65V. If it reaches 3.65V, set the SOC to 100, and then enter the insulation mode. Continue to determine whether the single low minimum temperature is greater than 15 degrees. If it is greater than 15 degrees, disconnect the heating relay and enter the pure charging mode.

[0046] 2.6 Pure charging mode: After entering the pure charging mode, first determine whether the main positive relay is closed. If not, go through the pre-charging process. If closed, directly send the voltage, current information and related status information defined in the pure charging mode. During this period, continue to determine whether the single cell voltage reaches 3.65V and the post-SOC is 100, and enter the insulation mode. Continue to determine whether the single cell temperature is less than 5 degrees. If it is less than 5 degrees, enter the charging and adding mode until either of the two triggers exit from the pure charging mode.

[0047] 2.7 Insulation mode: After entering the insulation mode, the charging request voltage, current and related status information defined in the insulation mode are directly sent (the request current is 0). At this time, it is determined whether the monomer temperature is less than 15 degrees. If it is less than, the heating relay is closed, and the charging request voltage and current required for heating are requested. Then the main positive relay is disconnected and heating begins. Until the temperature is greater than 25 degrees, the request current is restored to 0, the heating relay is disconnected, and pre-charging and power-on begins.

[0048] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A BMS control method for low-speed vehicles, It is characterized in that The following steps are involved: (1) Power-on mode allocation: When the BMS is awakened by a hard-wired signal, it first performs a self-test. After the self-test is completed, it determines whether there is a charging wake-up signal; (2) If there is a charging wake-up signal, the charging mode is entered, where the charging modes include pure heating mode, pure charging mode, charging and adding mode, and insulation mode. If there is no charging wake-up signal, it is determined whether there is a key signal wake-up. If so, the discharge mode is entered. If there is no key signal wake-up, the abnormal wake-up fault is entered; (2a) After entering the charging mode, first determine whether the SOC is 100%. If so, reset it to 99%. Then determine whether the temperature is greater than 0 degrees. If it is greater than 0 degrees, enter the single cell temperature judgment I. If it is greater than the value of single cell temperature judgment I, enter the pure charging mode. Otherwise, enter the charging and adding mode. If it is less than 0 degrees, enter the single cell temperature judgment II. If it is greater than the value of single cell temperature judgment II, enter the pure heating mode. Otherwise, report a low temperature fault. (3) Switching between charging and discharging modes: After entering charging mode, if the charging hard-line wake-up signal is detected to disappear, the charging power-down mode is entered. After the power-down state is completed, it is determined whether there is a key wake-up signal. If there is, the discharge mode is entered. If not, the sleep mode is entered. (4) After entering the discharge mode, if the key signal disappears or the charging signal appears, the system enters the discharge power-down mode. After the discharge power-down mode is completed, it is determined whether the charging signal still exists. If it exists, the system enters the charging mode. If not, the system enters the sleep mode. In step (2a), the value of temperature judgment I is 5 degrees, and the value of temperature judgment II is -35 degrees; In pure heating mode, when the temperature of a single cell is heated to more than 5 degrees, it enters charging and heating mode; When the temperature of the charging and heating mode is higher than 15 degrees, the pure charging mode is entered. When the SOC reaches 100 during heating, the heat preservation mode is entered. In pure charging mode, when the temperature drops below 5 degrees during charging, it enters the charging and charging mode. When the SOC reaches 100 during charging, it enters the warm-keeping mode. After entering the pure heating mode, first determine whether the main positive relay is closed. If not, proceed with the pre-charging process. If closed, directly send the charging request voltage, current and related status information defined in the pure heating mode. After sending, close the heating relay, delay 100ms to disconnect the main positive relay, start pure heating, and continue to determine whether the cell temperature is greater than 5 degrees. If it is greater than 5 degrees, enter the charging and adding mode. Otherwise, continue heating until the heating timeout fault is triggered.

2. A BMS control method for a low-speed vehicle as claimed in claim 1, It is characterized in that After entering the charge-while-charge mode, first determine whether the main positive relay is closed. If not, go through the pre-charging process. If closed, directly send the charging request voltage, current and related status information defined in the charge-while-charge mode. After sending, close the heating relay, and send the changed charging request voltage and current defined in the mode again. Then continue to determine whether the single cell voltage reaches 3.65V. If it reaches 3.65V, set the SOC to 100, and then enter the insulation mode. Continue to determine whether the single cell minimum temperature is greater than 15 degrees. If it is greater than 15 degrees, disconnect the heating relay and enter the pure charging mode.

3. A BMS control method for a low-speed vehicle as claimed in claim 1, It is characterized in that After entering the pure charging mode, first determine whether the main positive relay is closed. If not, go through the pre-charging process. If closed, directly send the voltage, current information and related status information requested by the pure charging mode. During this period, continue to determine whether the single cell voltage reaches 3.65V and the post-SOC is 100, and enter the insulation mode. Continue to determine whether the single cell temperature is less than 5 degrees. If it is less than 5 degrees, enter the charging and adding mode until either of the two triggers exit from the pure charging mode.

4. A BMS control method for a low-speed vehicle as claimed in claim 1, It is characterized in that After entering the insulation mode, the charging request voltage, current and related status information defined in the insulation mode are directly sent, where the requested current is 0. At this time, it is determined whether the cell temperature is less than 15 degrees. If it is less than 15 degrees, the heating relay is closed, and the charging request voltage and current required for heating are requested. Then the main positive relay is disconnected and heating is started. Until the temperature is greater than 25 degrees, the requested current is restored to 0, the heating relay is disconnected, and pre-charging and power-on are started.

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