Battery charging abnormity intelligent early warning system and early warning method

Abstract

The invention belongs to the technical field of battery charging, and relates to a battery charging abnormity intelligent early warning system and early warning method. The early warning method comprises the following steps: respectively acquiring a first real-time voltage Vin of a P1 point and a second real-time voltage Vout of a P2 point; and then calculating a real-time charging current i based on the first real-time voltage Vin and the second real-time voltage Vout, calculating a derivative # imgabs0 # of i to time, and finally judging whether charging is completed or not according to a value change rate of # imgabs1 #: if charging is completed, taking a current average value in a current time period as IMi and storing the IMi in the MCU chip as a current initial value for next charging, and meanwhile, the MCU chip controls the alarm device to charge to complete alarm. The early warning system provided by the invention can monitor the charging duration and the charging current in real time, judges the charging state in real time according to the values, and can automatically cut off the charging loop and end the charging process when the temperature is too high.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery charging, and relates to an intelligent early warning system and method for abnormal battery charging. Background Art

[0002] With the continuous progress of science and technology, electronic products using rechargeable batteries such as electric vehicles and mobile phones have been widely used. However, reports of fires caused by charging rechargeable batteries occur from time to time and result in heavy losses.

[0003] Currently, most existing chargers lack a charging abnormality detection and control section. Chargers only have a charging function without detection and power-off functions. Therefore, how to overcome the above disadvantages and alarm when charging abnormalities occur in the initial stage before a fire breaks out is an urgent need for current chargers.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art, and provide an intelligent early warning system and method for abnormal battery charging, which have the advantages of low cost and strong functions, and can be widely applied to chargers of other electronic products such as electric vehicles and mobile phones.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] On the one hand, the present invention provides an intelligent early warning system for abnormal battery charging, including an MCU chip and a charging circuit. The charging circuit includes a triode T1.

[0008] The emitter of the triode T1 is connected to one end of a first capacitor C1 and grounded, and the other end of the first capacitor C1 is connected to the device to be charged; the base of the triode T1 is connected to the MCU chip through a first resistor R1, and the collector of the triode T1 is connected to an input power supply through a fifth resistor R5 and a MOS power transistor M1; the gate of the MOS power transistor M1 is connected to the fifth resistor R5, the source is connected to the input power supply, and the drain is connected to the device to be charged. A second resistor R2 is also connected between the source of the MOS power transistor M1 and the collector of the triode T1.

[0009] The first real-time voltage V at point P1 in the charging circuit in is input into the first input terminal of the MCU chip through a first sampling circuit, and the second real-time voltage V at point P2 in the charging circuit out is input into the second input terminal of the MCU chip through a second sampling circuit. The third input terminal of the MCU chip also collects the real-time temperature information T of the MOS power transistor M1 through a third sampling circuit. The output terminal of the MCU chip is connected to an alarm device.

[0010] Specifically, the first sampling circuit includes a third resistor R3 and a first analog-to-digital conversion chip ADC1 that are sequentially connected between point P1 and the first input terminal of the MCU chip. One end of the third resistor R3 is connected to point P1, and the other end is grounded through a fourth resistor R4.

[0011] Specifically, the second sampling circuit includes a sixth resistor R6 and a second analog-to-digital conversion chip ADC2 that are sequentially connected between point P2 and the second input terminal of the MCU chip. One end of the sixth resistor R6 is connected to point P2, and the other end is grounded through a seventh resistor R7.

[0012] Specifically, the third sampling circuit includes a temperature sensor S1 and a third analog-to-digital conversion chip ADC3 connected in series. The temperature sensor S1 is used to monitor the real-time temperature information T of the MOS power transistor M1.

[0013] Specifically, the alarm device includes a sound alarm and a light alarm. The alarm sound is stored in advance in the storage unit of the MCU chip and is directly called and sent to the alarm device during an alarm. The alarm device contains a digital-to-analog conversion chip MS4344 for sound, which converts the digital sound transmitted from the MCU chip into an analog sound, and then plays the sound through an operational amplifier LM358 and a speaker; the light alarm of the alarm device is completed by a red LED and is directly controlled by the MCU chip to complete the alarm.

[0014] Further, the temperature sensor S1 is located within a circular area with the position of the MOS power transistor M1 as the center and a radius of 1 cm. For example, the distance between the temperature sensor S1 and the connection point of the heat sink and the copper skin at the bottom of the MOS power transistor is within 5 mm.

[0015] Before the entire early warning system is used, the relationship curve between the on-resistance R of the MOS power transistor M1 and the real-time temperature information T is stored in the storage unit of the MCU chip. The MCU chip can retrieve the corresponding on-resistance R according to the real-time temperature information T, which can effectively overcome the calculation error caused by the change of the on-resistance R with temperature. Then, according to the formula i = (V out - V in ) / R, the real-time current i is calculated to ensure the accuracy of the calculation result.

[0016] It should be supplemented that in this early warning system, the sampling frequencies of the first analog-to-digital conversion chip ADC1 and the second analog-to-digital conversion chip ADC2 are both not lower than 100 MHz. The third resistor R3, the fourth resistor R4, the sixth resistor R6, and the seventh resistor R7 all use high-precision resistors (error value < 10%). This design is beneficial to obtaining more accurate first real-time voltage V in and second real-time voltage V outIn addition, the outputs of the first analog-to-digital conversion chip ADC1, the second analog-to-digital conversion chip ADC2, and the third analog-to-digital conversion chip ADC3 are all 16-bit digital signals. This design can provide higher precision and achieve accurate measurement.

[0017] On the other hand, the present invention also provides an early warning method for applying the battery charging anomaly intelligent early warning system as described above. On the premise that the charging circuit is turned on, first obtain the first real-time voltage V at point P1 in and the second real-time voltage V at point P2 out respectively; then calculate the real-time charging current i based on the first real-time voltage V in and the second real-time voltage V out , and calculate the derivative of i with respect to time Finally, determine whether the charging is completed according to the value change rate: If the charging is completed, take the average current within the current time period as I Mi and store it in the MCU chip as the initial current value for the next charging. At the same time, the MCU chip controls the alarm device to give an alarm for the completion of charging.

[0018] During the entire charging process, when the temperature information T of the MOS power transistor M1 received by the MCU chip is greater than the preset threshold T h , it is determined that the charging is abnormal. The MCU chip disconnects the MOS power transistor M1, stops charging and starts the alarm device to give an alarm for charging anomaly; where is defined as the average value of all temperature information T in the past 5 days. The charging anomaly alarm sound is "charging anomaly", and at the same time, the red light-emitting diode in the alarm device flashes once every 0.2 s to prompt the user to disconnect the power supply.

[0019] In the initial stage of charging, if the real-time charging current i ≥ 0.1I Mi , it indicates that there is an electrical device connected, and the MOS power transistor M1 remains conducting; otherwise, the MCU chip disconnects the MOS power transistor M1 through the triode T1 and stops charging.

[0020] Furthermore, the early warning method specifically includes the following steps:

[0021] Step 1: On the premise that the charging circuit is turned on, the MCU chip turns on the MOS power transistor M1 to connect the input power supply through the triode T1, and obtains the first real-time voltage V at point P1 in and the second real-time voltage V at point P2 out respectively;

[0022] Step 2: Based on the first real-time voltage V in and the second real-time voltage V outCalculate the real-time charging current i;

[0023] Step 3: Calculate the derivative of the real-time charging current i with respect to time

[0024] Step 4: Determine whether the charging is completed according to the value change rate:

[0025] Step 4.1: If the value change rate < 3% and lasts for 30 min to 40 min, it is determined that the charging is completed, calculate the average current within this 30 min to 40 min, and use the average current as I Mi and store it as the initial current value for the next charging; where the value change rate is equal to the absolute value after taking the derivative with respect to t;

[0026] Step 4.2: The MCU chip controls the alarm device to broadcast the sound of "charging completed, please disconnect the power supply", and at the same time, the red light-emitting diode in the alarm device flashes once every specified time t1 to prompt the user to disconnect the power supply; if the MCU chip receives the first real-time voltage V at point P1 in is zero, it is determined that the input power supply has been disconnected by the user, otherwise, after continuously charging for 1 min to 10 min, the MCU automatically controls the MOS power transistor M1 to disconnect and stop charging.

[0027] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0028] 1) After the MCU chip controls the MOS power transistor to conduct, if the calculated real-time current value i ≥ 0.1I Mi , it indicates that there is an electrical device connected, and the MOS power transistor remains conducting; otherwise, the MCU chip controls the MOS power transistor M1 to disconnect and stop charging. Moreover, the storage unit of the MCU chip stores the curve relationship between the on-resistance R and the real-time temperature information T of the MOS power transistor M1. The real-time temperature information T of the MOS power transistor M1 is monitored in real time by the temperature sensor S1 disposed near the MOS power transistor M1. The real-time temperature information T is input into the MCU chip through the third analog-to-digital conversion chip ADC3. The MCU chip retrieves the corresponding on-resistance R of the MOS power transistor M1 according to the real-time temperature information T. By using this method, the calculation error caused by the change of the on-resistance R with temperature can be effectively overcome.

[0029] 2) The warning system provided by the present invention, the first analog-to-digital conversion chip, the second analog-to-digital conversion chip, and the third analog-to-digital conversion chip all output 16-bit digital signals, and the sampling frequencies of the first analog-to-digital conversion chip and the second analog-to-digital conversion chip are both not less than 100 MHz. The input of the first analog-to-digital conversion chip is the first real-time voltage at point P1, and the input of the second analog-to-digital conversion chip is the second real-time voltage at point P2. The first real-time voltage is the input voltage, and the second real-time voltage is the output voltage. The MCU chip controls the on / off of the MOS power transistor through a bipolar NPN transistor.

[0030] 3) The warning system provided by the present invention, the alarm device is used to provide acoustic and optical alarms. The alarm sound is stored in the MCU chip in advance and directly called and sent to the alarm device during alarm. The sound alarm of the alarm device includes a digital-to-analog conversion chip MS4344, which converts the digital sound transmitted by the MCU chip into an analog sound, and then plays the sound through an operational amplifier LM358 and a speaker. The optical alarm of the alarm device is completed by a red LED and is directly controlled by the MCU chip to achieve alarm.

[0031] 4) The warning system provided by the present invention can monitor the charging duration and the magnitude of the charging current in real time, and judge the charging state in real time according to the above values, and can automatically cut off the charging circuit and end the charging process when the temperature is too high. Brief Description of the Drawings

[0032] The drawings here are incorporated into the specification and form a part of this specification, and are used together with the specification to explain the principles of the present invention.

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1 is the principle block diagram of the battery charging anomaly intelligent warning system provided by the present invention;

[0035] Figure 2 is the flow chart of the battery charging anomaly intelligent warning method provided by the present invention.

[0036] Wherein: T1, triode; C1, first capacitor; R, on-resistance of MOS power transistor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; M1, MOS power transistor; V in , the first real-time voltage at point P1; V out, the second real-time voltage at point P2; S1, temperature sensor; T, real-time temperature information of the MOS power transistor; ADC1, the first analog-to-digital conversion chip; ADC2, the second analog-to-digital conversion chip; ADC3, the third analog-to-digital conversion chip. Detailed implementation mode

[0037] Here, the exemplary embodiments will be described in detail. The implementation modes described in the following exemplary embodiments do not represent all implementation modes consistent with the present invention. On the contrary, they are merely examples consistent with some aspects of the present invention detailed in the appended claims.

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the drawings and embodiments.

[0039] Embodiment

[0040] This embodiment provides an intelligent early warning system for abnormal battery charging. Its principle block diagram is as Figure 1 shown, including an MCU chip and a charging circuit. The charging circuit includes: a triode T1, a first capacitor C1, a fifth resistor R5, and a MOS power transistor M1;

[0041] The emitter of the triode T1 is connected to one end of the first capacitor C1 and grounded. The other end of the first capacitor C1 is connected to the device to be charged; the base of the triode T1 is connected to the MCU chip via a first resistor R1, and the collector of the triode T1 is connected to the input power supply via a fifth resistor R5 and the MOS power transistor M1; the gate of the MOS power transistor M1 is connected to the fifth resistor R5, the source is connected to the input power supply, and the drain is connected to the device to be charged. A second resistor R2 is also connected between the source of the MOS power transistor M1 and the collector of the triode T1;

[0042] The first real-time voltage V at point P1 in the charging circuit in is input into the first input terminal of the MCU chip through the first sampling circuit. The second real-time voltage V at point P2 in the charging circuit out is input into the second input terminal of the MCU chip through the second sampling circuit. The third input terminal of the MCU chip also collects the real-time temperature information T of the MOS power transistor M1 through the third sampling circuit. The output terminal of the MCU chip is connected to an alarm device.

[0043] Further, the first sampling circuit includes a third resistor R3 and a first analog-to-digital conversion chip ADC1 that are sequentially connected between point P1 and the first input terminal of the MCU chip. One end of the third resistor R3 is connected to point P1, and the other end is grounded through a fourth resistor R4.

[0044] Further, the second sampling circuit includes a sixth resistor R6 and a second analog-to-digital conversion chip ADC2 that are sequentially connected between point P2 and the second input terminal of the MCU chip. One end of the sixth resistor R6 is connected to point P2, and the other end is grounded through a seventh resistor R7.

[0045] Further, the third sampling circuit includes a temperature sensor S1 and a third analog-to-digital conversion chip ADC3 that are connected in series. The temperature sensor S1 is used to monitor the real-time temperature information T of the MOS power transistor M1.

[0046] Preferably, the alarm device includes a sound alarm and a light alarm. Among them, the sound alarm includes a digital-to-analog conversion chip MS4344 for sound, which can convert the digital sound transmitted by the MCU chip into an analog sound, and then play the sound through an operational amplifier LM358 and a speaker. The light alarm of the alarm device is completed by a red light LED and is directly controlled by the MCU chip to achieve an alarm.

[0047] In this early warning system, the temperature sensor S1 is located near the MOS power transistor. Specifically, it can be located within a circular area with the position of the MOS power transistor M1 as the center and a radius of 1 cm. For example, the distance between the temperature sensor S1 and the connection point of the heat sink and the copper skin at the bottom of the MOS power transistor is within 5 mm.

[0048] Before the entire early warning system is used, a relationship curve between the on-resistance R and the real-time temperature information T of the MOS power transistor M1 is stored in the storage unit of the MCU chip. The MCU chip can retrieve the corresponding on-resistance R according to the real-time temperature information T, effectively overcoming the calculation error caused by the change of the on-resistance R with temperature, and then calculate the real-time current i according to the formula i = (V out -V in ) / R to ensure the accuracy of the calculation result.

[0049] It should be added that in this early warning system, the sampling frequencies of the first analog-to-digital conversion chip ADC1 and the second analog-to-digital conversion chip ADC2 are both not lower than 100 MHz. The third resistor R3, the fourth resistor R4, the sixth resistor R6, and the seventh resistor R7 all use high-precision resistors (error value < 10%). This design is conducive to obtaining more accurate first real-time voltage and second real-time voltage. In addition, the outputs of the first analog-to-digital conversion chip ADC1, the second analog-to-digital conversion chip ADC2, and the third analog-to-digital conversion chip ADC3 are all 16-bit digital signals, which can provide higher precision and achieve accurate measurement.

[0050] In addition, this embodiment also provides an early warning method for applying the above battery charging abnormal intelligent early warning system. First, obtain the first real-time voltage V at point P1 respectively inand the second real-time voltage V at point P2 out ; then based on the first real-time voltage V in and the second real-time voltage V out calculate the real-time charging current i, and calculate the derivative of i with respect to time Finally, according to the rate of change of the value, determine whether the charging is completed: if the charging is completed, then take the average current within the current time period as I Mi and store it in the MCU chip as the initial current value for the next charging. At the same time, the MCU chip controls the alarm device to give a charging completion alarm.

[0051] It should be noted that during the entire charging process, when the temperature information T of the MOS power transistor M1 received by the MCU chip is greater than the preset threshold T h , it is determined that the charging is abnormal. The MCU chip disconnects the MOS power transistor M1, stops charging and starts the alarm device to give a charging abnormality alarm; where, define as the average value of all temperature information T in the past 5 days. The charging abnormality alarm sound is "charging abnormality", and at the same time, the red light-emitting diode in the alarm device flashes once every 0.2 s to prompt the user to disconnect the power supply.

[0052] See Figure 2 , the early warning method specifically includes the following steps:

[0053] Step 1, set the initial value of I Mi to 0.003 A. If the real-time charging current i ≥ 0.1I Mi , it indicates that an electrical device is connected. The MCU chip makes the MOS power transistor M1 conduct to connect the input power supply through the triode T1, and respectively obtains the first real-time voltage V at point P1 in and the second real-time voltage V at point P2 out ;

[0054] Step 2, calculate the real-time charging current i based on the first real-time voltage V in and the second real-time voltage V out ; set the on-resistance of the MOS power transistor M1 as R, then the real-time charging current is i = (V out - V in ) / R;

[0055] If i ≥ I MiIf it is 10 or less, it indicates that there is an electrical facility connected to the charging terminal, and the MOS power transistor M1 remains conducting. Otherwise, the MCU chip turns off the MOS power transistor M1 through the triode T1. The curve of the on-resistance R of the MOS power transistor M1 versus temperature is in the chip data of the MOS power transistor M1 and is stored in the storage unit of the MCU chip before the system is normally used. Figure 1 In Figure 1 , S1 is a temperature sensor disposed near the MOS power transistor M1 for measuring the real-time temperature information T of M1. T is input into the MCU chip through the third analog-to-digital conversion chip ADC3. The MCU chip retrieves the corresponding on-resistance R of the MOS power transistor M1 according to the real-time temperature information T, thus effectively overcoming the calculation error caused by the change of the on-resistance R with temperature.

[0056] Step 3: Calculate the derivative of the real-time charging current i with respect to time

[0057] Step 4: Determine whether the charging is completed according to the rate of change of the value:

[0058] Step 4.1: If the rate of change of the value < 3% and lasts for 30 min, it is determined that the charging is completed. Calculate the average current within these 30 min and use the average current as I Mi and store it as the initial current value for the next charging. Wherein, the rate of change of the value is equal to the absolute value after taking the derivative of

[0059] Step 4.2: The MCU chip controls the alarm device to broadcast the sound of "charging completed, please disconnect the power supply". At the same time, the red light-emitting diode in the alarm device flashes once every 1 s to prompt the user to disconnect the power supply. If the MCU chip receives the first real-time voltage V at point P1 in is zero, it is determined that the input power supply has been disconnected by the user. Otherwise, after continuously charging for 5 min, the MCU automatically controls the MOS power transistor M1 to turn off and stops charging.

[0060] It should be added that if the rate of change of the value < 3%, to ensure that the device to be charged can be fully charged and safely, the charging can last for 30 min to 40 min. When it is determined that the input power supply has not been disconnected by the user, the charging can last for 1 min to 10 min and then the MCU chip turns off the MOS power transistor M1 to stop charging.

[0061] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0062] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. An intelligent early warning system for abnormal battery charging, comprising an MCU chip and a charging circuit, characterized in that: The charging circuit comprises a transistor (T1), The emitter of the transistor (T1) is connected to one end of the first capacitor (C1) and is grounded, and the other end of the first capacitor (C1) is connected to the device to be charged; the base of the transistor (T1) is connected to the MCU chip via the first resistor (R1), and the collector of the transistor (T1) is connected to the input power supply via the fifth resistor (R5) and the MOS power transistor (M1); the gate of the MOS power transistor (M1) is connected to the fifth resistor (R5), the source is connected to the input power supply, and the drain is connected to the device to be charged, and a second resistor (R2) is also connected between the source of the MOS power transistor (M1) and the collector of the transistor (T1); The first real-time voltage (V in ) is input into the first input terminal of the MCU chip through the first sampling circuit, and the second real-time voltage (V out ) is input into the second input end of the MCU chip through the second sampling circuit, the third input end of the MCU chip also collects the real-time temperature information (T) of the MOS power transistor (M1) through the third sampling circuit, and the output end of the MCU chip is connected to the alarm device.

2. The battery charging abnormality intelligent early warning system according to claim 1 is characterized in that: The first sampling circuit comprises a third resistor (R3) and a first analog-to-digital conversion chip (ADC1) which are located between point P1 and a first input terminal of an MCU chip and are connected in sequence, one end of the third resistor (R3) is connected to point P1, and the other end is grounded via a fourth resistor (R4).

3. The battery charging abnormality intelligent early warning system according to claim 1 is characterized in that: The second sampling circuit comprises a sixth resistor (R6) and a second analog-to-digital conversion chip (ADC2) which are located between point P2 and the second input terminal of the MCU chip and are connected in sequence, one end of the sixth resistor (R6) is connected to point P2, and the other end is grounded via a seventh resistor (R7).

4. The battery charging abnormality intelligent early warning system according to claim 1 is characterized in that: The third sampling circuit comprises a temperature sensor (S1) and a third analog-to-digital conversion chip (ADC3) connected in series, and the temperature sensor (S1) is used to monitor real-time temperature information (T) of the MOS power transistor (M1).

5. The battery charging abnormality intelligent early warning system according to claim 4 is characterized in that: The temperature sensor (S1) is located in a circular area with a position of the MOS power transistor (M1) as the center and a radius of 1 cm.

6. The battery charging abnormality intelligent early warning system according to claim 1 is characterized in that: The storage unit of the MCU chip stores a relationship curve between the on-resistance (R) of the MOS power transistor (M1) and the real-time temperature information (T). The MCU chip can retrieve the corresponding on-resistance (R) according to the real-time temperature information (T), thereby ensuring the accuracy of the real-time current i.

7. An early warning method using the intelligent early warning system for abnormal battery charging as claimed in any one of claims 1 to 6, characterized in that: Under the premise that the charging circuit is turned on, first obtain the first real-time voltage (V in ) and the second real-time voltage (V out ); then based on the first real-time voltage (V in ) and the second real-time voltage (V out ) Calculate the real-time charging current i and the derivative of i with respect to time Finally, according to The rate of change of the value determines whether the charging is completed: If the charging is completed, the average current value in the current time period is taken as I Mi The current is stored in the MCU chip and used as the initial current value for the next charging. At the same time, the MCU chip controls the alarm device to sound an alarm when charging is completed.

8. The early warning method of the battery charging abnormality intelligent early warning system according to claim 7 is characterized in that: During the entire charging process, when the temperature information T of the MOS power transistor (M1) received by the MCU chip is greater than the preset threshold T h When the charging is abnormal, the MCU chip disconnects the MOS power transistor (M1), stops charging and starts the alarm device to alarm for abnormal charging; It is the average value of all temperature information T in the past 5 days.

9. The early warning method of the battery charging abnormality intelligent early warning system according to claim 7, characterized in that: In the initial stage of charging, if the real-time charging current i≥0.1I Mi , it indicates that there is a useful device connected and the MOS power transistor (M1) remains turned on; otherwise, the MCU chip disconnects the MOS power transistor (M1) through the transistor (T1) and stops charging.

10. The early warning method of the battery charging abnormality intelligent early warning system according to claim 7, characterized in that: The specific steps include: Step 1: Under the premise that the charging circuit is turned on, the MCU chip turns on the MOS power transistor (M1) through the transistor (T1) to connect to the input power supply, and obtains the first real-time voltage (V in ) and the second real-time voltage (V out ); Step 2: Based on the first real-time voltage (V in ) and the second real-time voltage (V out ) Calculate the real-time charging current i; Step 3: Calculate the derivative of the real-time charging current i with respect to time Step 4: According to The rate of change of the value determines whether charging is complete: Step 4.1: If If the value change rate is less than 3% and lasts for 30min to 40min, it is determined that the charging is completed, and the current average value within the 30min to 40min is calculated and the current average value is taken as I Mi And store it as the initial current value for the next charge; The rate of change of the value is equal to Take the derivative of t and then take the absolute value; Step 4.2, the MCU chip controls the alarm device to broadcast the sound "Charging is complete, please disconnect the power supply", and the red LED in the alarm device flashes once every specified time t1, prompting the user to disconnect the power supply; if the MCU chip receives the first real-time voltage (V in ) is zero, it is determined that the input power has been disconnected by the user. Otherwise, after charging continues for 1min to 10min, the MCU automatically controls the MOS power transistor (M1) to disconnect and stop charging.

Images