A method for charging a battery

Abstract

The present invention discloses a method for charging a battery, which charges the battery through a standby energy storage system, including S0, presetting; S1, prohibiting charging; S2, floating charging or pulse charging; S3, step constant voltage charging; S4, pre-charging; This method uses three ways to charge the battery. When the battery voltage or capacity is extremely low, pre-charging is adopted; when the battery voltage is greater than set value 1, step constant voltage charging is started, and when the current is very small or there is no current, the constant voltage value is made greater than the current battery voltage by ΔV and charging continues, repeating like this until the battery voltage is greater than set value n; then floating charging or pulse charging is started. This makes the battery temperature not rise too high and also reduces the speed of battery life shortening.

Description

Technical Field

[0001] The present invention relates to a method for charging a battery, and is particularly applicable to a backup energy storage system. Background Art

[0002] Currently, with the increasing popularity of the new energy industry, the popularity of electric vehicles is also increasing, and energy storage devices are becoming more and more popular. Devices with energy storage modules can be used in places without mains power, temporarily getting rid of the constraints of the mains power. The most commonly used energy storage modules are mainly composed of lithium batteries, including ternary lithium batteries, lithium iron phosphate batteries, lithium titanate batteries, etc. Moreover, battery energy storage modules are widely used in many fields, such as automobiles, data centers, portable devices, etc.

[0003] For existing battery energy storage modules, the charging speed and charging temperature have always been contradictory technical points. With the increasing maturity of technology in the power supply industry, the power of battery energy storage modules is getting higher and higher, and the conditions restricting battery charging are more inclined to the battery itself. If the charging current is always too large, lithium plating will occur, which will affect the service life of the battery.

[0004] Currently, the strategies for charging batteries generally include the following several types:

[0005] 1. Adopt a three-stage charging form. As Figure 1 shown, when starting to charge, the battery capacity is low and the battery voltage is also low, and a constant current method is adopted, that is, a fixed current is used to charge the battery; when the battery voltage reaches a first set value, a constant voltage mode is adopted, that is, a fixed voltage is used to charge the battery; when the battery voltage reaches a second set value, a floating charge voltage is used to charge the battery, that is, the battery is charged in a constant voltage mode. However, in the early stage of this charging form, the battery is always charged with a constant current, which makes the heat of the battery rise rapidly, and there are also potential safety hazards in charging with a large current all the time.

[0006] 2. Adopt a pulse charging form. As Figure 2 shown, the charging process is mainly divided into three important stages: pre-charging, using a small current to raise the battery voltage or battery capacity to a first set value; charging in a constant current mode, the charging current is charged at a constant value until the voltage or battery capacity reaches a second set value; buffering, when the voltage reaches the second set value, charging stops, and when the voltage returns to a third set value, charging is carried out in a constant current mode; and so on in a cycle. However, although this charging form always uses a constant current mode for charging, it must be within the current range allowed by the battery cell. The premise is to ensure safety and stability.

[0007] To overcome the above technical defects, it is urgent to research and develop a new method for charging a battery. Summary of the Invention

[0008] In view of the above existing technical problems, the present invention provides a method for charging a battery to effectively control the temperature of the battery and increase the service life of the battery.

[0009] To achieve the above object, the present invention provides a method for charging a battery. The battery is charged through a standby energy storage system, and the specific steps are as follows:

[0010] S0. Preset:

[0011] Set the threshold value of the battery current, the set values 1, 2,..., n of the battery voltage, where n is an integer greater than or equal to 2, and the maximum value of the battery voltage > set value n >... > set value 2 > set value 1 > the minimum value of the battery voltage;

[0012] S1. Charge prohibition:

[0013] Judge whether the current battery voltage is greater than or equal to the maximum value of the battery voltage;

[0014] If so, prohibit battery charging, and then enter S1;

[0015] If not, enter S2;

[0016] S2. Float charge or pulse charge:

[0017] Judge whether the current battery voltage is greater than or equal to set value n;

[0018] If so, the battery performs float charge or pulse charge, and then enters S1;

[0019] If not, enter S3;

[0020] S3. Step constant voltage charge:

[0021] Judge whether the current battery voltage is greater than or equal to set value n - 1;

[0022] a. If so, the battery performs step constant voltage charge according to the constant voltage value, where the constant voltage value = battery voltage + △V, and △V > 0; then judge whether the current battery voltage is greater than or equal to the constant voltage value, and whether the current charging current is less than the current threshold value; if so, update the constant voltage value, and the battery continues to perform step constant voltage charge according to the new constant voltage value, and then enters S1; if not, enter S1;

[0023] b. If not, judge whether the current battery voltage is greater than or equal to set value n - 2; if so, repeat step a; if not, judge whether the current battery voltage is greater than or equal to set value n - 3; judge each set value in turn like this until it is judged whether the current battery voltage is greater than or equal to set value 1; if so, repeat step a, if not, enter S4;

[0024] S4. Precharge:

[0025] The battery is pre-charged and then enters S1.

[0026] In the above technical solution, the present invention uses the mains power to charge the battery through a standby energy storage system, and charges the battery in three stages:

[0027] 1. When the battery voltage or capacity is extremely low, the present invention uses a small constant current pre-charging method to charge the battery;

[0028] 2. When the battery voltage is greater than or equal to the set value 1, the present invention starts the step constant voltage charging method, that is, measures the current battery voltage, makes the constant voltage value larger than the current battery voltage by △V, and charges with this constant voltage value; when the current is very small or there is no current, makes the constant voltage value larger than the current battery voltage by △V and continues to charge, repeating this cycle until the battery voltage is greater than the set value n;

[0029] 3. When the battery voltage is greater than or equal to the set value n, the present invention starts the floating charge method or the pulse charge method to charge the battery.

[0030] Furthermore, the standby energy storage system includes a rectifier bridge, a PFC module, a DC / DC module, an energy storage module, and an MCU module;

[0031] The rectifier bridge converts the input alternating current into a bread wave;

[0032] The PFC module converts the bread wave into direct current of about 380V;

[0033] The DC / DC module converts the output voltage of the PFC module into the voltage required by the battery;

[0034] The MCU module is arranged in the DC / DC module and is used to control the battery charging method;

[0035] And the input mains power is 220V alternating current, and the load is the battery.

[0036] In the above technical solution, the mains power converts the alternating current into a DC bread wave signal through the rectifier bridge, then corrects the power factor of the system through the PFC module and converts the bread wave signal into a DC signal of about 400V, and finally converts the electric energy into the energy of the battery through the DC / DC module. The DC / DC module directly controls the charging form of the power supply.

[0037] Furthermore, the MCU module uses a DSP chip and includes a PFC control function and an LLC control function.

[0038] Furthermore, the rectifier bridge includes four diodes.

[0039] Furthermore, the PFC module includes two MOS transistors.

[0040] Furthermore, the DC / DC module includes four MOS transistors.

[0041] In summary, compared with the prior art, the method of the present invention has the following technical advantages:

[0042] 1. Charging the battery in three stages is not only flexible and efficient but also safe and stable;

[0043] 2. After charging with a large current, the battery has a rest time, preventing the battery temperature from rising too high;

[0044] 3. It gives the opportunity for the lithium plating phenomenon to be reversible, converting metallic lithium into lithium ions and reducing the rate of battery life shortening. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the charging curve of the battery using a three-stage charging form in the prior art;

[0046] Figure 2 It is a schematic diagram of the charging curve of the battery using a pulse charging form in the prior art;

[0047] Figure 3a It is a schematic block diagram of a standby energy storage system in the prior art;

[0048] Figure 3b It is a schematic electrical block diagram of the standby energy storage using mains power to charge the energy storage module in the prior art;

[0049] Figure 3c It is a circuit embodiment of charging the battery according to the present invention;

[0050] Figure 4a It is a flowchart of the charging method with the set value 2 as the final charging voltage;

[0051] Figure 4b For Figure 3c the flowchart of the method of charging the battery with the circuit shown;

[0052] Figure 5 It is a schematic diagram of the charging curve of charging the battery according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] The description of the specific structure and function of the embodiments of the present invention disclosed herein is for illustrative purposes only for the embodiments of the present invention. Without departing from the spirit and significant features of the present invention, the present invention can be implemented in many different forms. Therefore, the disclosed embodiments of the present invention are for illustrative purposes only and should not be construed as a limitation of the present invention.

[0054] First, as Figure 3a shown, the present invention uses a backup energy storage system as the circuit for charging the battery. This backup energy storage system, also known as a portable power device, a portable energy storage system, etc., includes an energy storage module, a DC / DC module, a DC / AC module, a DC interface module, an AC interface module, and other modules. Among them, the energy storage module can be a battery or other energy storage devices; the DC / DC module is a DC-to-DC topology structure, such as BUCK, BOOST, LLC, forward, flyback, etc.; the DC / AC module is a DC-to-AC or AC-to-DC module, such as full-wave rectification, half-wave rectification, push-pull, PFC, etc.; the DC interface module refers to the way for DC devices or DC sources to access, such as a DC socket, a USB interface, a cigarette lighter, etc.; the AC interface module refers to the way for AC devices or AC sources to access, such as a two-pin socket, a three-pin socket, etc.; other modules include remaining modules such as display, sound, keys, etc.

[0055] As Figure 3b shown, this backup energy storage system uses the mains power to charge the energy storage module. The mains power converts the alternating current into a DC sine wave signal through a rectifier bridge, and then corrects the power factor of the system through the PFC module, and converts the sine wave signal into a DC signal of about 400V. Finally, the DC / DC module converts the electrical energy into the energy of the energy storage module, that is, the charging form of the battery is directly controlled by the DC / DC module.

[0056] As Figure 3c shown, in implementation, the present invention can use the conventional circuit of the backup energy storage system to charge the battery. The input mains power of this circuit is 220V alternating current, and the load is the battery; the MCU module is set in the DC / DC module and is used to control the charging method of the battery, including PFC control function and LLC control function. Generally, a DSP chip is selected, such as tms320F280049; the rectifier bridge converts the input alternating current into a sine wave; the PFC module converts the sine wave into a DC of about 380V; the DC / DC module converts the output voltage of the PFC module into the voltage required by the battery. Among them, the rectifier bridge includes four diodes, and uses the one-way conduction property of the diodes to convert the alternating current into a direct current; the PFC module includes two MOS tubes, and by controlling the on and off of MOS tubes Q1 and Q2, the phase of the current is adjusted to be consistent with the phase of the voltage, and the output voltage of the PFC module is controlled at about 380V DC; the DC / DC module includes four MOS tubes, and by controlling the four MOS tubes, the output of the PFC module is converted into a voltage that can charge the battery.

[0057] Secondly, as Figure 5 shown, the method of the present invention presets a current threshold, set values 1, 2,..., n of the battery voltage, and n is a positive integer ≥ 2, and divides the charging of the battery into three stages:

[0058] The first stage: When the battery voltage or capacity is extremely low, the battery is charged in a small constant current pre-charge mode.

[0059] The second stage: When the battery voltage reaches the set value 1, a step constant voltage charging method is adopted, that is, the current battery voltage is measured, the constant voltage value is made larger than the current battery voltage by △V, and the battery is charged with this constant voltage value; when the current is very small or there is no current, the constant voltage value is made larger than the current battery voltage by △V to continue charging the battery, and so on in a loop until the battery voltage reaches the set value n.

[0060] The third stage: When the battery voltage reaches the set value n, the battery mode enters the floating charge or pulse charge mode.

[0061] Such as Figure 4a As shown, specifically, the method for charging the battery of the present invention includes the following specific steps:

[0062] S0. Preset the current threshold of the battery, the set value 1 and set value 2 of the battery voltage, and the maximum value of the battery voltage > set value 2 > set value 1 > the minimum value of the battery voltage, and charge the battery with the set value 2 as the final charging voltage.

[0063] S1. Determine whether the current battery voltage is greater than or equal to the maximum value of the battery voltage;

[0064] If so, prohibit charging the battery, and then enter S1;

[0065] If not, then enter S2.

[0066] S2. Determine whether the current battery voltage is greater than or equal to the set value 2;

[0067] If so, perform floating charge or pulse charge on the battery;

[0068] If not, then enter S3.

[0069] S3. Determine whether the battery voltage is greater than or equal to the set value 1;

[0070] a. If so, perform step constant voltage charging on the battery, that is, measure the current battery voltage, set the constant voltage value to be larger than the current battery voltage by △V, and △V > 0, and charge the battery with this constant voltage value for constant voltage charging;

[0071] Then, determine whether the current battery voltage is greater than or equal to the constant voltage value 1, and whether the current battery current is less than the current threshold; if so, update the constant voltage value, set the constant voltage value to be larger than the current battery voltage by △V, and then enter S1;

[0072] b. If not, then enter S4.

[0073] In addition, if there are more than two set values for the battery voltage, then, in the order from the largest to the smallest set value, it is successively determined whether the current battery voltage is greater than the set value. If so, step a is repeated. If not, then the next set value is judged until the set value 1 is reached.

[0074] S4. Pre-charge the battery, and then enter S1.

[0075] As Figure 4b shown, in implementation, the method of the present invention uses the Figure 3c circuit shown to charge the battery, including the following specific steps:

[0076] A0. If the selected battery cell is a ternary lithium battery (with a voltage range of 2.5V - 4.2V and a capacity of 3000mAh), a 14-series 2-parallel battery pack assembly method is used. The voltage range of the battery is 35V - 58.8V, the minimum value of the battery voltage is 35V, and the maximum value of the battery voltage is 58.8V. Preset the set value n of the battery voltage to 56V,..., the set value 2 to 42V, and the set value 1 to 40V.

[0077] A1. Determine whether the battery voltage is greater than or equal to the maximum value 58.1V of the battery voltage;

[0078] If so, charging is prohibited, and then return to A1;

[0079] If not, then enter A2.

[0080] A2. Charge the battery in a floating charge or pulse charge mode:

[0081] Determine whether the battery voltage is greater than or equal to 56V;

[0082] If so, charge the battery in a dual-loop competition mode, with a constant current value of 6A and a constant voltage value of 58V, and then return to A1;

[0083] If not, then enter A3.

[0084] A3. Charge the battery in a step constant voltage charge mode:

[0085] Determine whether the battery voltage is greater than or equal to 42V;

[0086] a. If so, charge the battery in a dual-loop competition mode, with a constant current value of 6A and a constant voltage value of 44V;

[0087] Then, determine whether the charging current is less than 1A. If so, charge the battery in a dual-loop competition mode, with a constant current value of 6A and a constant voltage value of 46V, and then return to A1. If not, then return to A1.

[0088] b. If not, then determine whether the battery voltage is greater than or equal to 40V;

[0089] If so, charge the battery in a dual-loop competition mode with a constant current value of 6A and a constant voltage value of 42V; then determine whether the charging current is less than 1A; if so, charge the battery in a dual-loop competition mode with a constant current value of 6A and a constant voltage value of 44V, and then return to A1; if not, return to A1.

[0090] If not, enter A4.

[0091] Moreover, multiple battery voltage setting values can be inserted between the set values of 56V and 42V. Similarly, steps a and b are repeatedly operated.

[0092] A4. Charge the battery in a pre-charging manner:

[0093] Charge the battery in a dual-loop competition mode with a constant current value of 2A and a constant voltage value of 40V; then return to A1.

[0094] As Figure 4b and Figure 5 shown, it can be seen from the above that when the battery voltage is less than 40V, the method of the present invention uses a current of 2A to perform constant voltage pre-charging on the battery; when the battery voltage is greater than 40V and less than 58V, the method of the present invention charges the battery in a stepwise constant voltage manner, that is, when the voltage is 40V, the constant voltage value is set to 42V and the constant current value is 6A; when the battery voltage has not reached 42V, the battery is continuously charged with a constant current of 6A; when the battery voltage rises to 42V, the battery is charged with a constant voltage of 42V, and at the same time the charging current will gradually decrease. When the current decreases to 1A, the constant voltage value is updated to 44V, and the charging mode changes back to charging the battery with a constant current of 6A... and so on until the battery voltage reaches the fully charged voltage of the battery. This is a new charging method that effectively controls the temperature of the battery and increases the life of the battery. It is not only flexible and efficient but also safe and stable.

[0095] Although the preferred embodiments described in the present invention are only for the purpose of exemplary illustration, those skilled in the art should understand that various modifications, additions, and substitutions can be made without departing from the scope and spirit of the present invention disclosed in the appended claims.

Claims

1. A method for charging a battery, characterized in that, Charge the battery through a backup energy storage system, where the backup energy storage system includes a rectifier bridge, a PFC module, a DC / DC module, an energy storage module, and an MCU module; The rectifier bridge converts the input alternating current into a sine wave; The PFC module converts the sine wave into direct current of about 380V; The DC / DC module converts the output voltage of the PFC module into the voltage required by the battery; The MCU module is arranged in the DC / DC module and is used to control the charging method of the battery; And the input mains power is 220V alternating current, and the load is the battery; The method includes the following specific steps: S0. Preset: Set the threshold of the battery current, the set values 1, 2,..., n of the battery voltage, where n is an integer greater than or equal to 2, and the maximum value of the battery voltage > set value n >... > set value 2 > set value 1 > the minimum value of the battery voltage; S1. Charge prohibition: Judge whether the current battery voltage is greater than or equal to the maximum value of the battery voltage; If so, prohibit charging the battery, and then enter S1; If not, enter S2; S2. Float charge or pulse charge: Judge whether the current battery voltage is greater than or equal to the set value n; If so, the battery is charged by floating charge or pulse charge, and then enter S1; If not, enter S3; S3. Step constant voltage charge: Judge whether the current battery voltage is greater than or equal to the set value n - 1; a. If so, the battery performs step constant voltage charge according to the constant voltage value, where the constant voltage value = battery voltage + △V, and △V > 0; then judge whether the current battery voltage is greater than or equal to the constant voltage value, and whether the current charging current is less than the current threshold; if so, update the constant voltage value, and the battery continues to perform step constant voltage charge according to the new constant voltage value, and then enter S1; if not, enter S1; b. If not, judge whether the current battery voltage is greater than or equal to the set value n - 2; if so, repeat step a; if not, judge whether the current battery voltage is greater than or equal to the set value n - 3; judge each set value in turn like this until judging whether the current battery voltage is greater than or equal to the set value 1; if so, repeat step a, if not, enter S4; S4. Pre-charge: The battery is pre-charged, and then enter S1.

2. The method for charging a battery according to claim 1, wherein The MCU module uses a DSP chip and includes a PFC control function and an LLC control function.

3. The method for charging a battery according to claim 1, characterized in that, The rectifier bridge includes four diodes.

4. A method for charging a battery according to claim 1, characterized in that, The PFC module includes two MOS transistors.

5. A method for charging a battery according to claim 1, characterized in that, The DC / DC module includes four MOS transistors.

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