A precise battery charging system and an efficient charging method based on the system

Abstract

The present invention relates to an accurate battery charging system and an efficient charging method based on the system, comprising an AC / DC conversion module, a power conversion module, a rectifier module, an output module, a voltage and current feedback module, an output control module and a temperature measurement module connected in series in sequence, wherein the voltage and current feedback module has two input ends and two output ends, the two input ends of the voltage and current feedback module are respectively connected to a positive output terminal of the output module and a positive output terminal of the rectifier module, the two output ends of the voltage and current feedback module are respectively connected to an output control module and a power conversion module, the output control module has two input ends and two output ends, the two input ends of the output control module are respectively connected to an output end of the voltage and current feedback module and a temperature measurement module, the two output ends of the output control module are respectively connected to the output module and the power conversion module, the input end of the AC / DC conversion module is connected to the mains, and the temperature measurement module is used to measure the battery temperature and feed it back to the output control module.

Description

Technical Field

[0001] The invention relates to an accurate battery charging system and a high-efficiency charging method based on the system. Background Art

[0002] The charging current accuracy of a lithium battery charger determines whether the battery can be fully charged safely and efficiently. The charging current of many chargers on the market is inaccurate. A charging current that is too large can easily cause the battery to overheat, swell, or even explode, causing impossible damage. A charging current that is too small can cause slow charging and incomplete charging. For lithium batteries used in power tools, due to frequent charging and discharging needs, an incomplete battery pack will shorten its service life after multiple charging and discharging uses. Therefore, it is necessary to provide a precise battery charging system that can safely and efficiently charge the battery pack with a precise charging current and ensure that the battery pack is fully charged, thereby extending the battery pack's service life. Summary of the invention

[0003] The first technical problem to be solved by the present invention is to provide a precise battery charging system, which can accurately calculate the actual voltage of the battery, and accurately calculate the optimal charging voltage and charging current based on the actual voltage and the rated voltage, so as to charge the battery efficiently and safely and ensure that the battery is fully charged.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a precise battery charging system, comprising an AC / DC conversion module, a power conversion module, a rectifier module and an output module connected in series in sequence, and also comprising a voltage and current feedback module, an output control module and a temperature measurement module, wherein the voltage and current feedback module has two input ends and two output ends, the two input ends of the voltage and current feedback module are respectively connected to the positive output terminal of the output module and the positive output terminal of the rectifier module, the two output ends of the voltage and current feedback module are respectively connected to the output control module and the power conversion module, the output control module has two input ends and two output ends, the two input ends of the output control module are respectively connected to the output end of the voltage and current feedback module and the temperature measurement module, the two output ends of the output control module are respectively connected to the output module and the power conversion module, the input end of the AC / DC conversion module is connected to the mains, and the temperature measurement module is used to measure the battery temperature and feed it back to the output control module.

[0005] As a preferred solution, the power conversion module includes a first inductor, a first MOS tube connected in series in the first inductor loop, a first single-chip microcomputer connected to the G pole of the first MOS tube, and a second inductor having mutual inductance with the first inductor, both ends of the second inductor are connected to a rectifier module, and a voltage and current feedback module is electrically connected to the first single-chip microcomputer of the power conversion module.

[0006] As a preferred solution, the output module includes a second MOS tube, which is a P-channel MOS tube. The G pole of the second MOS tube is electrically connected to the output control module, the D pole of the second MOS tube is used to connect to the positive pole of the battery, and the S pole of the second MOS tube is connected to the positive output end of the rectifier module.

[0007] As a preferred solution, the voltage and current feedback module includes a first sampling resistor and a second sampling resistor, the two ends of the first sampling resistor are respectively connected to the positive output end of the output module and an input end of the output control module, and the two ends of the second sampling resistor are respectively connected to the positive output end of the rectifier module and the first single-chip microcomputer of the power conversion module.

[0008] As a preferred solution, the temperature measurement module includes a thermistor, the thermistor is in contact with the battery, one end of the thermistor is connected to a positive voltage, and the other end is connected to an input end of the output control module.

[0009] As a preferred solution, the output control module includes a second single chip microcomputer.

[0010] A further technical problem to be solved by the present invention is to provide an efficient charging method based on the above-mentioned battery charging system, which can charge the battery efficiently and safely to ensure that the battery is fully charged.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is: based on the efficient charging method of the above battery charging system, firstly, the AC / DC conversion circuit is connected to the mains and the mains is converted into direct current, and the direct current is sent to the power conversion module and provides the voltage V+ required for operation to each module of the battery charging system. At this time, the first single-chip microcomputer of the power conversion module waits to receive the actual voltage value of the battery, the first MOS tube is disconnected, and the entire charging system is actually in a dormant state;

[0012] Then, the output module is connected to the battery, the positive electrode of the output module is connected to the positive electrode of the battery, and the negative electrode of the output module is connected to the negative electrode of the battery. At this time, the first sampling resistor of the voltage and current feedback module samples the positive electrode voltage of the battery and sends it to an input terminal of the second single-chip microcomputer of the output control module. The thermistor of the temperature measurement module detects the battery temperature and sends it to another input terminal of the second single-chip microcomputer of the output control module. The second single-chip microcomputer calculates the actual voltage value of the battery at room temperature according to the received battery voltage and battery temperature using a preset calculation formula, and the calculation formula is obtained by fitting the actual experimental data, and sends a signal representing the actual voltage value to the first single-chip microcomputer of the power conversion module; at the same time, the second single-chip microcomputer of the output control module calculates the current battery capacity according to the ratio of the preset battery rated voltage value to the actual voltage value, and when it is judged that the battery capacity is not full and the battery temperature is lower than the safe temperature, the second MOS tube of the output module is controlled to be turned on, and the battery charging system starts to work to charge the battery;

[0013] When charging starts, the first single-chip microcomputer of the power conversion module calculates the optimal charging power according to the received signal representing the actual voltage value, and outputs the optimal charging power to the rectifier module by controlling the opening and closing frequency of the first MOS tube. After the optimal charging power is rectified by the rectifier module, the charging current and charging voltage that meet the battery charging requirements are output, and the battery is charged through the output module;

[0014] After charging starts, the second sampling resistor of the voltage circuit feedback module samples the voltage value of the positive output end of the rectifier module, and after the sampling resistor steps down the voltage, sends it to the first single-chip microcomputer of the power conversion module. The first single-chip microcomputer U calculates the current size and the actual charging power according to the received voltage value and the resistance value of the sampling resistor, calculates the power loss according to the difference between the actual charging power and the aforementioned optimal charging power, and compensates for the optimal charging power until the actual charging power output by the rectifier module is equal to the optimal charging power;

[0015] During the charging process, the power conversion module obtains the required output power by switching the first MOS tube at a certain frequency. Each time the first MOS tube is disconnected, the voltage and current feedback module detects the current voltage value of the battery, calculates the actual voltage value of the battery at normal temperature in combination with the battery temperature, and sends it to the first single-chip microcomputer of the power conversion module. The first single-chip microcomputer calculates the new optimal output power again and overwrites the old optimal output power.

[0016] During the charging process, the thermistor of the temperature measurement module continuously monitors the battery temperature. When the battery temperature approaches a safe temperature, the output module is cut off and charging stops. When the temperature drops to a chargeable temperature, charging starts again.

[0017] The beneficial effects of the present invention are as follows: the present invention receives the voltage of the battery in the non-charging state sampled by the voltage and current feedback module through the output control module, and then combines it with the battery temperature detected by the temperature measurement module, and calculates the actual voltage of the battery at normal temperature according to the functional relationship between the temperature and the battery voltage, and then sends an electrical signal representing the actual voltage value to the first single-chip microcomputer of the power conversion module. The first single-chip microcomputer of the power conversion module controls the opening and closing frequency of the first MOS tube according to the received electrical signal, thereby adjusting the output power of the power conversion module so that the output power is more matched with the current battery capacity to obtain accurate charging current and high charging efficiency. At the same time, the output control module can control the on and off state of the output module according to the current battery capacity and battery temperature to avoid overheating and overcharging of the battery.

[0018] At the same time, the voltage and current feedback module also samples the current at the positive output end of the rectifier module and feeds it back to the power conversion module. The power conversion module calculates the output voltage and output power of the rectifier module based on the received current size and the resistance value of the sampling resistor, and further calculates the power loss of the output power of the power conversion module after rectification by the rectifier module, and compensates for it, so that the power output of the rectifier module better matches the current battery capacity, thereby further obtaining more efficient charging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein:

[0020] Figure 1 is a schematic diagram of the battery charging system of the present invention;

[0021] Figure 2 is a circuit diagram of the power conversion module of the present invention;

[0022] Figure 3 is a circuit diagram of the output module of the present invention;

[0023] Figure 4 is a circuit diagram of the voltage and current feedback module of the present invention;

[0024] Figure 5 is a circuit diagram of the temperature measurement module of the present invention;

[0025] Figure 6 It is a circuit diagram of the output control module of the present invention. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0027] like Figure 1 to Figure 6 As shown, the precise battery charging system of the present invention comprises an AC / DC conversion module, a power conversion module, a rectifier module and an output module connected in series, and also comprises a voltage and current feedback module, an output control module and a temperature measurement module, such as Figure 6As shown, the output control module is preferably a second single-chip computer U2. The voltage and current feedback module has two input terminals and two output terminals, the two input terminals of the voltage and current feedback module are respectively connected to the positive output terminal of the output module and the positive output terminal of the rectifier module, the two output terminals of the voltage and current feedback module are respectively connected to the output control module and the power conversion module, the output control module has two input terminals and two output terminals, the two input terminals of the output control module are respectively connected to the output terminal of the voltage and current feedback module and the temperature measurement module, the two output terminals of the output control module are respectively connected to the output module and the power conversion module, the input terminal of the AC / DC conversion module is connected to the mains, and the temperature measurement module is used to measure the battery temperature and feed it back to the output control module.

[0028] like Figure 2 As shown, in this embodiment, the power conversion module includes a first inductor L1, a first MOS tube Q1 connected in series in the loop of the first inductor L1, a first single-chip computer U1 connected to the G pole of the first MOS tube Q1, and a second inductor L2 having mutual inductance with the first inductor L1, two ends of the second inductor L2 are connected to the rectifier module, and the voltage and current feedback module is electrically connected to the first single-chip computer U1 of the power conversion module.

[0029] like Figure 3 As shown, in this embodiment, the output module includes a second MOS tube Q2, the second MOS tube Q2 is a P-channel MOS tube, the G pole of the second MOS tube is electrically connected to the output control module, the D pole of the second MOS tube is used to connect the positive electrode of the battery, and the S pole of the second MOS tube is connected to the positive output end of the rectifier module.

[0030] like Figure 4 As shown, the voltage and current feedback module includes a first sampling resistor R1 and a second sampling resistor R2, the two ends of the first sampling resistor R1 are respectively connected to the positive output end of the output module and an input end of the output control module, and the two ends of the second sampling resistor R2 are respectively connected to the positive output end of the rectifier module and the first single-chip computer U1 of the power conversion module.

[0031] like Figure 5 As shown, in this embodiment, the temperature measurement module includes a thermistor NTC, the thermistor NTC is in contact with the battery, one end of the thermistor NTC is connected to a positive voltage, and the other end is connected to an input end of the output control module.

[0032] The method of using the above battery charging system for efficient charging is: Figure 1 to Figure 6As shown, firstly, the AC / DC conversion circuit is connected to the mains and the mains is converted into direct current. The direct current is sent to the power conversion module and at the same time, the voltage V+ required for operation is provided to each module of the battery charging system. At this time, the first single-chip microcomputer U1 of the power conversion module waits to receive the actual voltage value of the battery, the first MOS tube Q1 is disconnected, and the entire charging system is actually in a dormant state.

[0033] Then, the output module is connected to the battery, the positive electrode of the output module is connected to the positive electrode of the battery, and the negative electrode of the output module is connected to the negative electrode of the battery. At this time, the first sampling resistor R1 of the voltage and current feedback module samples the positive electrode voltage of the battery and sends it to an input terminal of the second single-chip microcomputer U2 of the output control module. The thermistor NTC of the temperature measurement module detects the battery temperature and sends it to another input terminal of the second single-chip microcomputer U2 of the output control module. The second single-chip microcomputer U2 calculates the actual voltage value of the battery at room temperature according to the received battery voltage and battery temperature using a preset calculation formula. The calculation formula is obtained by fitting the actual experimental data, and a signal representing the actual voltage value is sent to the first single-chip microcomputer U1 of the power conversion module; at the same time, the second single-chip microcomputer U2 of the output control module calculates the current battery capacity according to the ratio of the preset battery rated voltage value to the actual voltage value. When it is determined that the battery capacity is not full and the battery temperature is lower than the safe temperature, the second MOS tube Q2 of the output module is controlled to be turned on, and the battery charging system starts to work to charge the battery.

[0034] When charging starts, the first single-chip microcomputer U1 of the power conversion module calculates the optimal charging power based on the received signal representing the actual voltage value, and outputs the optimal charging power to the rectifier module by controlling the opening and closing frequency of the first MOS tube Q1. After the optimal charging power is rectified by the rectifier module, the charging current and charging voltage that meet the battery charging requirements are output, and the battery is charged through the output module.

[0035] After charging starts, the second sampling resistor R2 of the voltage circuit feedback module samples the voltage value at the positive output end of the rectifier module, and after being stepped down by the sampling resistor R2, it is sent to the first single-chip computer U1 of the power conversion module. The first single-chip computer U1 calculates the current and the actual charging power based on the received voltage value and the resistance value of the sampling resistor R2, calculates the power loss based on the difference between the actual charging power and the aforementioned optimal charging power, and compensates for the optimal charging power until the actual charging power output by the rectifier module is equal to the optimal charging power.

[0036] During the charging process, since the power conversion module obtains the required output power by switching the first MOS tube Q1 at a certain frequency, from a microscopic point of view, the actual charging process of the battery is an intermittent process. Each time the first MOS tube Q1 is disconnected, the voltage and current feedback module can detect the current voltage value of the battery once, calculate the actual voltage value of the battery at normal temperature in combination with the battery temperature, and send it to the first single-chip microcomputer U1 of the power conversion module. The first single-chip microcomputer U1 calculates the new optimal output power again and overwrites the old optimal output power. Therefore, during the entire charging process, the battery charging system described in the present invention continuously corrects the optimal charging output power, thereby obtaining high charging efficiency and ensuring that the battery is fully charged.

[0037] During the charging process, the thermistor NTC of the temperature measurement module continuously monitors the battery temperature. When the battery temperature approaches the safe temperature, the output module is cut off and charging stops. When the temperature drops to the charging temperature, charging starts again, thus ensuring the safety of the charging process.

[0038] The above embodiments are only illustrative of the principles and effects of the invention, as well as some embodiments of its application, and are not intended to limit the invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the invention, and all of these belong to the protection scope of the invention.

Claims

1. A precise battery charging system, comprising an AC / DC conversion module, a power conversion module, a rectifier module and an output module connected in series, characterized in that: It also includes a voltage and current feedback module, an output control module and a temperature measurement module, wherein the voltage and current feedback module has two input ends and two output ends, the two input ends of the voltage and current feedback module are respectively connected to the positive output terminal of the output module and the positive output terminal of the rectifier module, the two output ends of the voltage and current feedback module are respectively connected to the output control module and the power conversion module, the output control module has two input ends and two output ends, the two input ends of the output control module are respectively connected to the output end of the voltage and current feedback module and the temperature measurement module, the two output ends of the output control module are respectively connected to the output module and the power conversion module, the input end of the AC / DC conversion module is connected to the mains, and the temperature measurement module is used to measure the battery temperature and feed it back to the output control module; The power conversion module includes a first inductor, a first MOS tube connected in series in the first inductor loop, a first single-chip microcomputer connected to the G pole of the first MOS tube, and a second inductor having mutual inductance with the first inductor, two ends of the second inductor are connected to a rectifier module, and a voltage and current feedback module is electrically connected to the first single-chip microcomputer of the power conversion module; The output module includes a second MOS tube, which is a P-channel MOS tube. The G pole of the second MOS tube is electrically connected to the output control module, the D pole of the second MOS tube is used to connect to the positive electrode of the battery, and the S pole of the second MOS tube is connected to the positive output end of the rectifier module; The output control module calculates the actual voltage value of the battery at room temperature based on the received battery voltage and battery temperature using a preset calculation formula, the calculation formula is obtained by fitting the actual experimental data, and sends a signal representing the actual voltage value to the power conversion module. At the same time, the output control module calculates the current battery capacity based on the ratio of the preset battery rated voltage value to the actual voltage value. When it is determined that the battery capacity is not full and the battery temperature is lower than the safe temperature, the second MOS tube of the output module is controlled to be turned on.

2. The battery charging system according to claim 1, characterized in that: The voltage and current feedback module includes a first sampling resistor and a second sampling resistor, wherein two ends of the first sampling resistor are respectively connected to the positive output end of the output module and an input end of the output control module, and two ends of the second sampling resistor are respectively connected to the positive output end of the rectifier module and the first single-chip microcomputer of the power conversion module.

3. The battery charging system according to claim 2, characterized in that: The temperature measurement module includes a thermistor, which is in contact with the battery. One end of the thermistor is connected to a positive voltage, and the other end is connected to an input end of the output control module.

4. The battery charging system according to claim 3, characterized in that: The output control module includes a second single chip microcomputer.

5. The high-efficiency charging method of the battery charging system according to claim 4, characterized in that: First, the AC / DC conversion circuit is connected to the mains and converted into direct current. The direct current is sent to the power conversion module and provides the voltage V+ required for operation to each module of the battery charging system. At this time, the first single-chip microcomputer of the power conversion module waits to receive the actual voltage value of the battery, the first MOS tube is disconnected, and the entire charging system is actually in a dormant state; Then, the output module is connected to the battery, the positive electrode of the output module is connected to the positive electrode of the battery, and the negative electrode of the output module is connected to the negative electrode of the battery. At this time, the first sampling resistor of the voltage and current feedback module samples the positive electrode voltage of the battery and sends it to an input terminal of the second single-chip microcomputer of the output control module. The thermistor of the temperature measurement module detects the battery temperature and sends it to another input terminal of the second single-chip microcomputer of the output control module. The second single-chip microcomputer calculates the actual voltage value of the battery at room temperature according to the received battery voltage and battery temperature using a preset calculation formula, and the calculation formula is obtained by fitting the actual experimental data, and sends a signal representing the actual voltage value to the first single-chip microcomputer of the power conversion module; at the same time, the second single-chip microcomputer of the output control module calculates the current battery capacity according to the ratio of the preset battery rated voltage value to the actual voltage value, and when it is judged that the battery capacity is not full and the battery temperature is lower than the safe temperature, the second MOS tube of the output module is controlled to be turned on, and the battery charging system starts to work to charge the battery; When charging starts, the first single-chip microcomputer of the power conversion module calculates the optimal charging power according to the received signal representing the actual voltage value, and outputs the optimal charging power to the rectifier module by controlling the opening and closing frequency of the first MOS tube. After the optimal charging power is rectified by the rectifier module, the charging current and charging voltage that meet the battery charging requirements are output, and the battery is charged through the output module; After charging starts, the second sampling resistor of the voltage circuit feedback module samples the voltage value of the positive output end of the rectifier module, and after the sampling resistor steps down the voltage, sends it to the first single-chip microcomputer of the power conversion module. The first single-chip microcomputer calculates the current and the actual charging power according to the received voltage value and the resistance value of the sampling resistor, calculates the power loss according to the difference between the actual charging power and the aforementioned optimal charging power, and compensates for the optimal charging power until the actual charging power output by the rectifier module is equal to the optimal charging power; During the charging process, the power conversion module obtains the required output power by switching the first MOS tube at a certain frequency. Each time the first MOS tube is disconnected, the voltage and current feedback module detects the current voltage value of the battery, calculates the actual voltage value of the battery at normal temperature in combination with the battery temperature, and sends it to the first single-chip microcomputer of the power conversion module. The first single-chip microcomputer calculates the new optimal output power again and overwrites the old optimal output power. During the charging process, the thermistor of the temperature measurement module continuously monitors the battery temperature. When the battery temperature approaches a safe temperature, the output module is cut off and charging stops. When the temperature drops to a chargeable temperature, charging starts again.

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