Charger with battery heating protection function

Abstract

The invention relates to the technical field of chargers, and discloses a charger with a battery heating protection function, and the charger comprises a charging module which is used for charging a battery; the heating module is used for heating the battery; the temperature acquisition module is used for acquiring an environment temperature and a battery temperature; the heating control module is configured with a preheating strategy, and the heating control module calculates an environment heat dissipation coefficient according to the preheating strategy; the decision module judges a current charging heating mode based on the battery temperature and the battery temperature change rate, controls the charging current of the charging module and the heating power of the heating module based on the charging heating mode, and controls the heating and charging of the battery based on the battery temperature and the battery temperature change rate; and good heating and charging effects can be obtained while thermal runaway is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of chargers, and in particular to a charger with a battery heating protection function. Background Art

[0002] In today's transportation sector, electric bicycles have rapidly gained widespread popularity around the world due to their convenience and environmental friendliness. As one of the main power sources for electric bicycles, the performance of lead-acid batteries is directly related to the user experience and market development of electric bicycles. With the continuous growth in the number of electric bicycles, research on the performance optimization of lead-acid batteries has become increasingly in-depth. The charging and discharging performance of lead-acid batteries is extremely sensitive to the ambient temperature of use. Especially in cold winter, low temperature environments will significantly deteriorate the charging and discharging performance of the battery, thereby seriously shortening the mileage of electric bicycles. To solve this problem, designers proposed the idea of ​​installing a heating device inside the battery to heat the battery. This idea attempts to improve the performance of the battery in low temperature environments to a certain extent, but it exposes many disadvantages in actual applications. Generally, chargers with battery heating functions do not have a relatively complete heating overload function, which will cause the following problems: 1) Heating short circuit protection uses a fuse for protection, which can easily cause the fuse to blow, thus losing the heating function of the battery; 2) Heating protection uses a fuse resistor. To ensure that the resistor is not easily damaged, the power is often relatively large. When a short circuit occurs in the heating part, the fuse resistor cannot be disconnected, which may easily burn the charger or cause a fire. 3) When a short circuit occurs in the heating part, the heating MOS switch is damaged due to excessive current, and the heating cannot be turned off, causing the heating circuit to continue heating the battery, which may cause thermal runaway or over-discharge of the battery. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a charger with a battery heating protection function, which controls the heating and charging of the battery based on the battery temperature and the rate of change of the battery temperature, thereby avoiding thermal runaway and achieving better heating and charging effects.

[0004] To achieve the above object, the present invention provides the following technical solutions: A charger with battery heating protection function, comprising: A charging module, wherein the charging module is used to charge the battery; A heating module, wherein the heating module is used to heat the battery; A temperature acquisition module, which is used to collect ambient temperature and battery temperature; A heating control module, wherein the heating control module is configured with a preheating strategy, and the heating control module calculates an environmental heat dissipation coefficient according to the preheating strategy; A decision module is provided, wherein the decision module determines a current charging and heating mode based on the battery temperature and the battery temperature change rate, and controls a charging current of the charging module and a heating power of the heating module based on the charging and heating mode.

[0005] Furthermore, the decision module is pre-configured with a first critical condition and a second critical condition. When the first critical condition is met, the charger switches from the normal operation mode to the early warning operation mode. When the second critical condition is met, the charger switches from the early warning mode to the critical operation mode. When in normal operation mode, the charger operates at a preset charging current and heating power; When in the early warning operation mode, the charger adjusts the charging current based on a preset charging power dynamic adjustment formula and adjusts the heating power based on a preset heating power dynamic adjustment formula; When in critical operating mode, the charger stops heating and charging.

[0006] Furthermore, the first critical condition is specifically: , The second critical condition is specifically: , Where T represents the current battery temperature, Indicates the preset warning temperature threshold. Indicates the preset critical temperature threshold, represents the rate of temperature change, Indicates the safe temperature change rate threshold.

[0007] Furthermore, the charging power dynamic adjustment formula is specifically: , , in Indicates the actual charging current, Indicates the maximum allowable charging current, Indicates the minimum allowable charging current, Indicates the charging current derating ratio, represents the warning temperature threshold, max() is the maximum value function, , is the preset weight coefficient, The dynamic adjustment formula of heating power is specifically: , , in Indicates the actual heating power, Indicates the heating power derating ratio, P indicates the maximum allowable heating power, represents the minimum allowable heating power, max() is the maximum value function, , is the preset weight coefficient, Indicates the warning temperature threshold.

[0008] Furthermore, the calculation formula of the safe temperature change rate threshold is specifically: , in, Indicates the safe temperature change rate threshold, Indicates the preset warning temperature threshold. Indicates the preset critical temperature threshold, Indicates the preset time allowed for heating up.

[0009] Furthermore, the decision module is configured with a weight coefficient correction strategy, which includes calculating the estimated temperature based on the temperature estimation formula, obtaining the variance of the difference between the actual battery temperature and the estimated temperature, and calculating the difference , , The corresponding variance under the combination, select the group with the smallest variance value as the selected weight coefficient.

[0010] Furthermore, the temperature estimation formula is specifically: , = + *t, in, Represents the thermal capacity of the battery, represents the battery resistance, represents the ambient heat dissipation coefficient, Indicates the ambient temperature, represents the estimated temperature of the battery at time n, represents the estimated temperature of the battery at time n+1, and t represents the unit time.

[0011] Furthermore, the decision module is configured with a dynamic security threshold adjustment strategy, and the dynamic security threshold adjustment strategy includes , in represents the updated safe temperature change rate threshold, c represents the preset temperature weight parameter, Indicates the preset critical temperature threshold, Indicates the preset temperature reference value.

[0012] Furthermore, the preheating strategy includes obtaining the current ambient temperature, heating the battery to a preset reference temperature and then stopping the heating, and collecting the correlation between the cooling temperature and time of the battery to obtain the ambient heat dissipation coefficient.

[0013] Beneficial effects of the present invention: The battery heating protection charger described in the present invention solves the technical defects of traditional chargers through multi-module collaborative control and hierarchical decision-making strategies, and specifically sets three operation control modes. In the normal operation mode, it runs at full power to maximize the charging and heating efficiency. In the early warning mode, the temperature increase is suppressed to balance the charging speed and safety. In the critical operation mode, the charging path is immediately cut off to avoid thermal runaway. At the same time, the battery temperature and the rate of change of the battery temperature are used to control the battery heating and charging. The weight coefficient can be optimized after comparing the measured temperature data with the estimated data to ensure that the error between the model prediction and the measured temperature is minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the system architecture of the present invention; Figure 2 It is a structural schematic diagram of a power conversion unit in the present invention; Figure 3 It is a structural schematic diagram of the battery heating and protection unit in the present invention; Figure 4 It is a structural schematic diagram of the constant current and constant voltage control unit in the present invention; Figure 5 It is a structural schematic diagram of the MCU control unit in the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0018] like Figure 1 As shown, a charger with a battery heating protection function in this embodiment includes A charging module, wherein the charging module is used to charge the battery; A heating module, wherein the heating module is used to heat the battery; A temperature acquisition module, which is used to collect ambient temperature and battery temperature; A heating control module, wherein the heating control module is configured with a preheating strategy, and the heating control module calculates an environmental heat dissipation coefficient according to the preheating strategy; A decision module is provided, wherein the decision module determines a current charging and heating mode based on the battery temperature and the battery temperature change rate, and controls a charging current of the charging module and a heating power of the heating module based on the charging and heating mode.

[0019] First of all, before each charging, the environmental heat dissipation coefficient must be determined. In this application, the environmental heat dissipation coefficient is obtained based on the preheating strategy: the preheating strategy includes obtaining the current ambient temperature. If the current ambient temperature is greater than a certain temperature, the battery temperature can be maintained in a suitable range without heating; if the current ambient temperature is less than or equal to a certain temperature, the battery temperature will be at risk of being too low, and the battery is preheated, which can also be used to obtain the environmental heat dissipation coefficient. After heating the battery to the preset reference temperature, stop heating, and collect the correlation between the battery's cooling temperature and time to obtain the environmental heat dissipation coefficient.

[0020] In the present application, three operating modes are provided for heating and charging the battery, including a normal operating mode, a warning operating mode, and a critical operating mode.

[0021] Furthermore, the decision module is pre-configured with a first critical condition and a second critical condition. When the first critical condition is met, the charger switches from the normal operation mode to the early warning operation mode. When the second critical condition is met, the charger switches from the early warning mode to the critical operation mode. When in normal operation mode, the charger operates at a preset charging current and heating power; When in the early warning operation mode, the charger adjusts the charging current based on a preset charging power dynamic adjustment formula and adjusts the heating power based on a preset heating power dynamic adjustment formula; When in critical operating mode, the charger stops heating and charging.

[0022] Furthermore, the first critical condition is specifically: , The second critical condition is specifically: , Where T represents the current battery temperature, Indicates the preset warning temperature threshold. Indicates the preset critical temperature threshold, represents the rate of temperature change, Indicates the safe temperature change rate threshold.

[0023] when The charger operates in normal operation mode. , .

[0024] Furthermore, the charging power dynamic adjustment formula is specifically: , , in Indicates the actual charging current, Indicates the maximum allowable charging current, Indicates the minimum allowable charging current, Indicates the charging current derating ratio, represents the warning temperature threshold, max() is the maximum value function, , is the preset weight coefficient.

[0025] The dynamic adjustment formula of heating power is specifically: , , in Indicates the actual heating power, Indicates the heating power derating ratio, P indicates the maximum allowable heating power, represents the minimum allowable heating power, max() is the maximum value function, , is the preset weight coefficient, Indicates the warning temperature threshold.

[0026] Here , , , The weights can be confirmed through experiments, and the weight parameters can all be set to 0.5, and then gradually adjusted according to the collected data.

[0027] Furthermore, the decision module is configured with a weight coefficient correction strategy, which includes calculating the estimated temperature based on the temperature estimation formula, obtaining the variance of the difference between the actual battery temperature and the estimated temperature, and calculating the difference , , The corresponding variance under the combination, select the group with the smallest variance value as the selected weight coefficient.

[0028] Furthermore, the temperature estimation formula is specifically: , = + *t, in, Represents the thermal capacity of the battery, represents the battery resistance, represents the ambient heat dissipation coefficient, Indicates the ambient temperature, represents the estimated temperature of the battery at time n, represents the estimated temperature of the battery at time n+1, and t represents the unit time.

[0029] Furthermore, the calculation formula of the safe temperature change rate threshold is specifically: , in, Indicates the safe temperature change rate threshold, Indicates the preset warning temperature threshold. Indicates the preset critical temperature threshold, Indicates the preset time allowed for heating up.

[0030] Furthermore, the decision module is configured with a dynamic security threshold adjustment strategy, and the dynamic security threshold adjustment strategy includes , in represents the updated safe temperature change rate threshold, c represents the preset temperature weight parameter, Indicates the preset critical temperature threshold, Indicates the preset temperature reference value.

[0031] Working principle: For circuit diagram, please refer to Figures 2 to 5The voltage DC+ converted by the power conversion circuit is stabilized by the constant current and constant voltage control unit, and one path is connected through QA1, RA1 and GND to charge the battery, and the other path is connected through QA2, R33, battery heating component and GND to heat the battery. The conduction of QA1 is controlled by Q3, Q4, Q5, PC3 and MCU pin 8.

[0032] Under normal circumstances, the MCU detects the battery temperature through the signal transmitted by J1 pin 3 to control the opening and closing of the heating switch MOS tube QA2. When heating is required, the MCU pin 8 outputs a low-level signal, which turns off Q5 through R14, and Q4 is forward-biased through R36, R38 and R40. It pulls down the gate voltage of QA2 through R39, thereby turning on QA2 and turning on the heating switch. Otherwise, it is different. This is the normal operating mode mentioned above.

[0033] When it is detected that the first critical condition is met, the early warning operation mode is entered, and the heating component and the charging component need to be controlled. The control process is as above.

[0034] When it is detected that the second critical condition is met, the critical operation mode is entered, and heating and charging are stopped. In addition, the charger is also provided with an anti-short circuit structure to prevent the short circuit of the heating component from damaging the charger. When the heating component is short-circuited, due to the large short-circuit current, the voltage drop generated on R33 turns on the light-emitting diode inside PC3 through R32, thereby turning on PC3 pin 4 to pin 3, and the 12V voltage turns on Q5 through D6 and R41, and then turns off Q4 through D5 and R38, so that QA2 loses the lower bias and turns off, stopping the heating output. After Q5 is turned on, the base of Q3 is turned on by R37. This turned-on voltage speeds up the closing time of QA2, avoiding QA2 from being damaged due to long high current conduction time, thereby realizing the function of heating short-circuit protection. After the PC3 pin 4 to pin 3 is turned on, the 12V voltage is sent to the MCU pin 3 through R5. This voltage triggers the MCU's internal ELVD protection function, so that its pin 8 outputs a high level, further turning off the heating switch QA2, thereby achieving the purpose of self-locking heating protection. R15 is the MCU pin 3 voltage divider resistor and C12 is its filter capacitor. After the MCU self-locks the heating function, the heating switch is turned on every 2 seconds. If the ELVD protection is triggered 6 times in a row, the heating function will not be started again during this charging, and the indicator light will flash to remind the user that there is a problem with the battery heating component and it needs to be handled in time.

[0035] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A charger with battery heating protection function, characterized in that: include A charging module, wherein the charging module is used to charge the battery; A heating module, wherein the heating module is used to heat the battery; A temperature acquisition module, which is used to collect ambient temperature and battery temperature; A heating control module, wherein the heating control module is configured with a preheating strategy, and the heating control module calculates an environmental heat dissipation coefficient according to the preheating strategy; A decision module is provided, wherein the decision module determines a current charging and heating mode based on the battery temperature and the battery temperature change rate, and controls a charging current of the charging module and a heating power of the heating module based on the charging and heating mode.

2. The charger with battery heating protection function according to claim 1, characterized in that: The decision module is pre-configured with a first critical condition and a second critical condition. When the first critical condition is met, the charger switches from the normal operation mode to the early warning operation mode. When the second critical condition is met, the charger switches from the early warning mode to the critical operation mode. When in normal operation mode, the charger operates at a preset charging current and heating power; When in the early warning operation mode, the charger adjusts the charging current based on a preset charging power dynamic adjustment formula and adjusts the heating power based on a preset heating power dynamic adjustment formula; When in critical operating mode, the charger stops heating and charging.

3. The charger with battery heating protection function according to claim 2, characterized in that: The first critical condition is specifically: , The second critical condition is specifically: , Where T represents the current battery temperature, Indicates the preset warning temperature threshold. Indicates the preset critical temperature threshold, represents the rate of temperature change, Indicates the safe temperature change rate threshold.

4. The charger with battery heating protection function according to claim 2, characterized in that: The charging power dynamic adjustment formula is specifically: ， ， in Indicates the actual charging current, Indicates the maximum allowable charging current, Indicates the minimum allowable charging current, Indicates the charging current derating ratio, represents the warning temperature threshold, max() is the maximum value function, , is the preset weight coefficient, The dynamic adjustment formula of heating power is specifically: ， ， in Indicates the actual heating power, Indicates the heating power derating ratio, P indicates the maximum allowable heating power, represents the minimum allowable heating power, max() is the maximum value function, , is the preset weight coefficient, Indicates the warning temperature threshold.

5. The charger with battery heating protection function according to claim 2, characterized in that: The calculation formula of the safe temperature change rate threshold is specifically: ， in, Indicates the safe temperature change rate threshold, Indicates the preset warning temperature threshold. Indicates the preset critical temperature threshold, Indicates the preset time allowed for heating up.

6. The charger with battery heating protection function according to claim 4, characterized in that: The decision module is configured with a weight coefficient correction strategy, which includes calculating the estimated temperature based on the temperature estimation formula, obtaining the variance of the difference between the actual battery temperature and the estimated temperature, and calculating the difference , , The corresponding variance under the combination, select the group with the smallest variance value as the selected weight coefficient.

7. The charger with battery heating protection function according to claim 6, characterized in that: The temperature estimation formula is specifically: ， = + *t， in, Represents the thermal capacity of the battery, represents the battery resistance, represents the ambient heat dissipation coefficient, Indicates the ambient temperature, represents the estimated temperature of the battery at time n, represents the estimated temperature of the battery at time n+1, and t represents the unit time.

8. The charger with battery heating protection function according to claim 2, characterized in that: The decision module is configured with a dynamic security threshold adjustment strategy, and the dynamic security threshold adjustment strategy includes , in represents the updated safe temperature change rate threshold, c represents the preset temperature weight parameter, Indicates the preset critical temperature threshold, Indicates the preset temperature reference value.

9. The charger with battery heating protection function according to claim 2, characterized in that: The preheating strategy includes obtaining the current ambient temperature, heating the battery to a preset reference temperature and then stopping the heating, and collecting the correlation between the cooling temperature and time of the battery to obtain the ambient heat dissipation coefficient.

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