BMS charging method at low temperature

Abstract

The invention discloses a BMS (Battery Management System) charging method at low temperature. The method comprises the following steps: calibrating a pulse backlash current value of a battery cell at low temperature; at a low temperature, when the BMS starts to charge, only the heating film is started for heating; in the heating process of the heating film, the BMS intermittently sends a pulse large-current charging request to the quick charging pile; and in response to the pulse large-current request, the fast charging pile starts to charge. According to the BMS charging method at the low temperature, when part of vehicles start to be charged in winter Tmin smaller than or equal to 0 DEG C, only the heating film is started for heating, in the fast charging mode, the pulse large-current charging request is intermittently sent to the fast charging pile, and after the fast charging pile detects the large-current request, safety risks are not caused to a battery, and the charging time is shortened. And the rapid charging pile does not detect continuous low-current charging, so that the charging is automatically stopped.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle charging, and more specifically, to a BMS charging method at low temperature. Background Art

[0002] At present, in new energy commercial vehicles, considering the requirements of cost control, lithium iron phosphate battery packs basically use heating film heating and natural cooling mode. The heating rate of the heating film is generally 15℃-25℃ per hour. When the minimum explosion temperature of the battery Tmin≤0℃, lithium iron phosphate batteries are generally not allowed to be continuously charged to prevent safety risks caused by lithium precipitation. When some vehicles reach -10℃ in winter and go to public charging piles to charge, because only the heating film heating is started at Tmin≤0℃ at the beginning, some social fast charging piles will automatically stop charging when continuous low current charging is detected, causing trouble to customers.

[0003] Therefore, a BMS charging method at low temperatures is urgently needed. Summary of the invention

[0004] The object of the present invention is to provide a BMS charging method at low temperature to solve the above-mentioned problems in the prior art. It can intermittently send pulse high-current charging requests to the fast charging pile. After the fast charging pile detects the high-current request, it will not stop charging.

[0005] The present invention provides a BMS charging method at low temperature, which includes:

[0006] Calibrate the pulse re-rush current value of the battery cell at low temperature;

[0007] At low temperatures, when the BMS starts charging, only the heating film is activated for heating;

[0008] During the heating process of the heating film, the BMS intermittently sends pulsed high-current charging requests to the fast charging pile;

[0009] In response to the pulse high current request, the fast charging pile starts charging.

[0010] In the BMS charging method at low temperature as described above, preferably, the calibrating the pulse backrush current value of the battery cell at low temperature specifically includes:

[0011] Calibrate the maximum charging current value of the battery cell at low temperature for 30 seconds, obtain the Map table, and store the calibration result in the BMS software.

[0012] In the BMS charging method at low temperature as described above, preferably, the Map table is used to indicate the corresponding relationship between the battery temperature, the battery SOC and the maximum charging current value lasting for 30 seconds.

[0013] As described above, the BMS charging method at low temperature, wherein, preferably, in the Map table, the minimum value of the battery temperature is -10°C, the maximum value is 35°C, and the calibration interval is 5°C; the minimum value of the battery SOC is 0%, the maximum value is 100%, and the calibration interval is 5%.

[0014] The BMS charging method at low temperature as described above, wherein preferably, when the BMS starts charging at low temperature, only the heating film is started for heating, specifically comprising:

[0015] When Tmin≤0℃, when BMS starts charging, only the heating film is started for heating.

[0016] In the BMS charging method at low temperature as described above, preferably, during the heating process of the heating film, the BMS intermittently sends a pulse high current charging request to the fast charging pile, specifically including:

[0017] During the heating process of the heating film, the BMS intermittently sends pulse high-current charging requests to the fast charging pile based on the calibration results of the pulse rebound current value of the battery cell at low temperature.

[0018] In the BMS charging method at low temperature as described above, preferably, during the heating process of the heating film, the BMS intermittently sends a pulse high current charging request to the fast charging pile according to the calibration result of the pulse backwash current value of the battery cell at low temperature, specifically including:

[0019] When Tmin≤0℃, BMS uses closed-loop 0A current for charging;

[0020] After the duration of the BMS charging with a closed-loop 0A current exceeds a first preset time threshold, determining whether Tmin is still less than or equal to 0° C.;

[0021] If yes, then according to the calibration result of the pulse backrush current value of the battery cell at low temperature, the maximum pulse current is obtained by looking up the table;

[0022] BMS uses the maximum pulse current obtained by table lookup for charging;

[0023] After the time for charging using the maximum pulse current obtained by the BMS table exceeds the second preset time threshold, it is determined whether Tmin is still less than or equal to 0°C;

[0024] If yes, return to the step of charging with closed-loop 0A current.

[0025] The BMS charging method at low temperature as described above, wherein preferably, during the heating process of the heating film, the BMS intermittently sends a pulse high current charging request to the fast charging pile according to the calibration result of the pulse backwash current value of the battery cell at low temperature, and further includes:

[0026] After the duration of the BMS charging with a closed-loop current of 0 A exceeds a first preset time threshold, if Tmin>0° C., the BMS charges with a closed-loop current of 20 A.

[0027] In the BMS charging method at low temperature as described above, preferably, the first time threshold is 5 minutes and the second time threshold is 30 seconds.

[0028] The present invention provides a BMS charging method under low temperature. When some vehicles start charging in winter when Tmin≤0℃, only the heating film is started for heating. In the fast charging mode, pulsed high-current charging requests are intermittently sent to the fast charging pile. After the fast charging pile detects the high-current request, it neither causes safety risks to the battery nor causes the fast charging pile to detect continuous low-current charging, thereby causing automatic stopping of charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described below with reference to the accompanying drawings, in which:

[0030] Figure 1 A flow chart of an embodiment of a BMS charging method at low temperature provided by the present invention;

[0031] Figure 2 It is a schematic diagram of the calibration results of the pulse re-rush current value of the battery cell at low temperature;

[0032] Figure 3 A logic diagram of the fast charging strategy of an embodiment of the BMS charging method at low temperature provided by the present invention. DETAILED DESCRIPTION

[0033] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the present disclosure and its application or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the components and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary and not as limiting.

[0034] The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. The words "include" or "comprises" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements. "Up", "down" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] In the present disclosure, when a specific component is described as being located between a first component and a second component, there may or may not be an intermediate component between the specific component and the first component or the second component. When a specific component is described as being connected to other components, the specific component may be directly connected to the other components without an intermediate component, or may not be directly connected to the other components but have an intermediate component.

[0036] All terms (including technical terms or scientific terms) used in the present disclosure have the same meanings as those understood by ordinary technicians in the field to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, such as general dictionaries, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0037] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0038] With the current charging scheme, when Tmin≤0℃, only the heating film heating is started. When the heating film is heated to above Tmin>0℃, the charging current is gradually increased as the temperature rises. When Tmin≥15℃, the heating film heating is stopped.

[0039] Since only the heating film is started when Tmin≤0℃, the heating current of the heating film is generally 8-12A, which is very small, equivalent to the charging current of slow charging. When some social fast charging piles detect continuous low current charging, they will automatically stop charging, causing trouble to customers.

[0040] like Figure 1 As shown, the BMS charging method at low temperature provided by this embodiment includes the following steps in actual implementation:

[0041] Step S1, calibrating the pulse recharge current value of the battery cell at low temperature.

[0042] Specifically, Figure 2As shown, the maximum charging current value of the battery cell at low temperature for 30 seconds is calibrated to obtain a Map table, and the calibration result is stored in the BMS software. The Map table is used to indicate the corresponding relationship between the battery temperature, the battery SOC and the maximum charging current value for 30 seconds.

[0043] In one embodiment of the present invention, Figure 2 As shown in the Map table, the minimum value of the battery temperature is -10°C, the maximum value is 35°C, and the calibration interval is 5°C; the minimum value of the battery SOC is 0%, the maximum value is 100%, and the calibration interval is 5%. It should be noted that the present invention does not specifically limit the calibrated minimum battery temperature, maximum battery temperature, battery temperature interval, minimum battery SOC, maximum battery SOC, SOC calibration interval, etc.

[0044] Step S2: At low temperatures, when the BMS starts charging, only the heating film is activated for heating.

[0045] Specifically, when Tmin≤0°C and the BMS starts charging, only the heating film is started for heating.

[0046] Step S3: During the heating process of the heating film, the BMS intermittently sends pulsed high-current charging requests to the fast charging pile.

[0047] Although lithium iron phosphate batteries are not allowed to be continuously charged when Tmin≤0℃, they support pulse charging at a low rate of 30s. When Tmin≤0℃, in fast charging mode, intermittent pulse high current charging requests will neither cause safety risks to the battery nor cause the fast charging pile to detect continuous low current charging, thereby automatically stopping charging. Specifically, during the heating process of the heating film, the BMS intermittently sends pulse high current charging requests to the fast charging pile based on the calibration results of the pulse backwash current value of the battery cell at low temperature.

[0048] like Figure 3 As shown, in one embodiment of the BMS charging method at low temperature of the present invention, the step S3 may specifically include:

[0049] Step S31: When Tmin≤0°C, the BMS uses a closed-loop 0A current for charging.

[0050] Step S32: after the duration of the BMS charging with the closed-loop 0A current exceeds the first preset time threshold, determine whether Tmin is still less than or equal to 0°C.

[0051] Exemplarily, the first time threshold is 5 minutes.

[0052] Step S33: If yes, then according to the calibration result of the pulse backrush current value of the battery cell at low temperature, the maximum pulse current is obtained by looking up the table.

[0053] Step S34: The BMS uses the maximum pulse current obtained by looking up the table to charge.

[0054] BMS uses maximum pulse current for charging, which is very large, equivalent to fast charging.

[0055] Step S35: After the time for charging with the maximum pulse current obtained by table lookup by the BMS exceeds the second preset time threshold, it is determined whether Tmin is still less than or equal to 0°C.

[0056] Exemplarily, the second time threshold is 30 seconds. It should be noted that the present invention does not specifically limit the values ​​of the first time threshold and the second time threshold.

[0057] Step S36: If yes, return to the step of charging with a closed-loop 0A current.

[0058] Further, in one embodiment of the BMS charging method at low temperature of the present invention, the step S3 may also include:

[0059] Step S37: After the duration of the BMS charging with a closed-loop current of 0 A exceeds a first preset time threshold, if Tmin>0° C., the BMS charges with a closed-loop current of 20 A.

[0060] Step S4: In response to the pulse high current request, the fast charging pile starts charging.

[0061] Once the fast charging pile detects a pulse high current request, it will not stop charging.

[0062] The BMS charging method at low temperature provided by the embodiment of the present invention, when some vehicles start charging in winter when Tmin≤0℃, only starts the heating film heating. In the fast charging mode, by intermittently sending pulsed high-current charging requests to the fast charging pile, after the fast charging pile detects the high-current request, it will neither cause safety risks to the battery nor cause the fast charging pile to detect continuous low-current charging, thereby causing automatic stopping of charging.

[0063] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0064] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A BMS charging method at low temperature, characterized in that: include: Calibrate the pulse re-rush current value of the battery cell at low temperature; At low temperatures, when the BMS starts charging, only the heating film is activated for heating; During the heating process of the heating film, the BMS intermittently sends pulsed high-current charging requests to the fast charging pile; In response to the pulse high current request, the fast charging pile starts charging.

2. The BMS charging method at low temperature according to claim 1, characterized in that: The calibrating pulse backrush current value of the battery cell at low temperature specifically includes: Calibrate the maximum charging current value of the battery cell at low temperature for 30 seconds, obtain the Map table, and store the calibration result in the BMS software.

3. The BMS charging method at low temperature according to claim 2, characterized in that: The Map table is used to indicate the corresponding relationship between the battery temperature, the battery SOC and the maximum charging current value lasting for 30 seconds.

4. The BMS charging method at low temperature according to claim 1, characterized in that: In the Map table, the minimum value of the battery temperature is -10°C, the maximum value is 35°C, and the calibration interval is 5°C; the minimum value of the battery SOC is 0%, the maximum value is 100%, and the calibration interval is 5%.

5. The BMS charging method at low temperature according to claim 1, characterized in that: When the BMS starts charging at low temperature, only the heating film is started for heating, specifically including: When Tmin≤0℃, when BMS starts charging, only the heating film is started for heating.

6. The BMS charging method at low temperature according to claim 1, characterized in that: During the heating process of the heating film, the BMS intermittently sends a pulse high current charging request to the fast charging pile, specifically including: During the heating process of the heating film, the BMS intermittently sends pulse high-current charging requests to the fast charging pile based on the calibration results of the pulse rebound current value of the battery cell at low temperature.

7. The BMS charging method at low temperature according to claim 6, characterized in that: During the heating process of the heating film, the BMS intermittently sends a pulse high current charging request to the fast charging pile according to the calibration result of the pulse backrush current value of the battery cell at low temperature, specifically including: When Tmin≤0℃, BMS uses closed-loop 0A current for charging; After the duration of the BMS charging with a closed-loop 0A current exceeds a first preset time threshold, determining whether Tmin is still less than or equal to 0° C.; If yes, then according to the calibration result of the pulse backrush current value of the battery cell at low temperature, the maximum pulse current is obtained by looking up the table; BMS uses the maximum pulse current obtained by table lookup for charging; After the time for charging using the maximum pulse current obtained by the BMS table exceeds the second preset time threshold, it is determined whether Tmin is still less than or equal to 0°C; If yes, return to the step of charging with closed-loop 0A current.

8. The BMS charging method at low temperature according to claim 7, characterized in that: During the heating process of the heating film, the BMS intermittently sends a pulse high current charging request to the fast charging pile according to the calibration result of the pulse backrush current value of the battery cell at low temperature, and also includes: After the duration of the BMS charging with a closed-loop current of 0 A exceeds a first preset time threshold, if Tmin>0° C., the BMS charges with a closed-loop current of 20 A.

9. The BMS charging method at low temperature according to claim 7, characterized in that: The first time threshold is 5 minutes, and the second time threshold is 30 seconds.

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