A battery charging method and system

Abstract

This invention relates to a battery charging method and system, belonging to the field of battery charging technology. It includes a constant current charging stage and a constant voltage charging stage. The battery charging method includes: obtaining the highest temperature T1 during the constant current charging stage; calculating the target control temperature T2 of the battery during the constant voltage charging stage, the calculation formula for the target control temperature being: [formula missing], where [value missing] is a trade-off parameter between charging speed and cell temperature, 0 < [value missing], and [value missing] is the current charging ambient temperature; when the battery is in the constant voltage charging stage, the temperature of the cell is controlled so that the cell temperature T satisfies the following relationship: T2 ≤ T ≤ T1. This invention increases the average temperature of the cell during the constant voltage charging stage by heating the cell, reduces cell polarization, increases the charging current during the constant voltage charging stage, and improves the charging speed.

Description

Technical Field

[0001] This invention relates to the field of battery charging technology, and in particular to a battery charging method and system. Background Technology

[0002] Currently, most lithium battery-powered mobile devices on the market use fast charging as one of their main selling points, as faster charging speeds can improve the user experience. Existing fast charging solutions primarily use charging current and cutoff voltage as control variables, with lithium plating and temperature rise as constraints. Among these, constant current / constant voltage (DC / DC) / multi-step DC / DC charging methods can ensure no lithium plating and no overheating during the constant current phase, resulting in rapid charging. The current during the constant current phase can also be adjusted according to ambient temperature changes, fully utilizing the temperature and maintaining a safe, permissible range to charge the battery cell as quickly as possible. Once the full battery voltage reaches the set upper voltage limit, charging enters the constant voltage charging phase, where the cell terminal voltage remains constant, and the current and temperature decrease rapidly. However, there is a lack of effective strategies to further improve charging speed during the constant voltage phase. Therefore, how to improve the charging speed during the constant voltage charging stage of lithium batteries is a technical problem that urgently needs to be solved. Summary of the Invention

[0003] The purpose of this invention is to provide a battery charging method and system to improve the charging speed of the battery during the constant voltage charging stage. To achieve the above objectives, the present invention provides the following solution: A battery charging method includes a constant current charging stage and a constant voltage charging stage, wherein the battery charging method includes: Obtain the highest temperature T1 during the constant current charging phase. The target control temperature T2 of the battery during the constant voltage charging phase is calculated using the following formula: , This is a trade-off parameter between charging speed and cell temperature, where 0 < < , The current charging ambient temperature; When the battery is in the constant voltage charging stage, the temperature of the cell is controlled so that the temperature T of the cell satisfies the following relationship: T2≤T≤T1. Optionally, the constant current charging stage is the stage in which the battery cell begins charging at any state of charge. Optionally, the temperature of the battery cell can be controlled, specifically by heating the battery cell. Optionally, the battery charging method further includes: Charging stops when the battery charging current drops to the first preset value. Optionally, the battery charging method further includes: Charging stops when the battery cell's charging capacity reaches a second preset value. A battery charging system includes a constant current charging stage and a constant voltage charging stage, wherein the battery charging system comprises: The acquisition module is used to acquire the highest temperature T1 during the constant current charging stage; The calculation module is used to calculate the target control temperature T2 of the battery during the constant voltage charging phase. The formula for calculating the target control temperature is as follows: , This is a trade-off parameter between charging speed and cell temperature, where 0 < < , The current charging ambient temperature; The control module is used to control the temperature of the battery cell when the battery is in the constant voltage charging stage, so that the temperature T of the battery cell satisfies the following relationship: T2≤T≤T1. Optionally, the control module includes: A control unit is used to heat the battery cell. Optionally, the battery charging system further includes: The first charging control module is used to control the charging system to stop charging the battery when the battery charging current drops to a first preset value. Optionally, the battery charging system further includes: The second charging control module is used to control the charging system to stop charging the battery when the charging capacity of the battery cell reaches a second preset value. According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: This invention discloses a battery charging method and system, including a constant current charging stage and a constant voltage charging stage. The battery charging method includes: obtaining the highest temperature T1 during the constant current charging stage; and calculating the target control temperature T2 of the battery during the constant voltage charging stage, wherein the calculation formula for the target control temperature is: , This is a trade-off parameter between charging speed and cell temperature, where 0 < < , The ambient temperature is the current charging temperature. When the battery is in the constant voltage charging stage, the temperature of the battery cell is controlled so that the temperature T of the battery cell satisfies the following relationship: T2≤T≤T1. This invention increases the average temperature of the battery cell in the constant voltage charging stage by heating the battery cell, thereby reducing cell polarization, increasing the charging current in the constant voltage charging stage, and improving the charging speed. Attached Figure Description

[0004] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 A flowchart of a battery charging method provided in an embodiment of the present invention; Figure 2 This is a comparison chart of cell temperatures under the constant pressure heating method and the constant pressure no heating method provided in this embodiment; Figure 3 A comparison diagram of charging current and charging speed under the constant pressure heating method and the constant pressure no heating method provided in this embodiment; Figure 4 This is a comparison chart of charging time under the constant pressure heating method and the constant pressure no heating method provided in this embodiment; Figure 5 This is a comparison chart of the charging capacity under the constant pressure heating method and the constant pressure non-heating method provided in this embodiment. Detailed Implementation

[0005] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The terms "first," "second," "third," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the objects described in this way can be used interchangeably where appropriate. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. In this invention, the accompanying drawings and embodiments used to describe the principles of the invention are for illustrative purposes only and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that the principles of the invention can be implemented in any suitably arranged system. Exemplary embodiments will be described in detail, examples of which are illustrated in the accompanying drawings. Furthermore, a terminal according to an exemplary embodiment will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings refer to like elements. The terminology used in this specification is for describing particular embodiments only and is not intended to represent the concept of the invention. Unless the context clearly distinguishes them, singular expressions encompass plural expressions. In this specification, it should be understood that terms such as “comprising,” “having,” and “containing” are intended to describe the possibility of the presence of the features, numbers, steps, actions, or combinations thereof disclosed in this specification, and are not intended to exclude the possibility of the presence or addition of one or more other features, numbers, steps, actions, or combinations thereof. Like reference numerals in the drawings refer to like parts. The purpose of this invention is to provide a battery charging method and system that can improve the charging speed without affecting the maximum charging temperature or causing lithium plating. To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment discloses a battery charging method, including a constant current charging stage and a constant voltage charging stage. The battery charging method includes: Step 1: Obtain the highest temperature T1 during the constant current charging phase. In this embodiment, the state of charge at the start of charging can be any value, meaning that the battery cell can start charging at any state of charge. In this embodiment, the highest temperature T1 can be measured by a temperature sensor or obtained from the storage unit of the charging system. Further explanation of the battery cell and battery of the present invention: A battery cell refers to a single cell consisting only of a positive electrode, a negative electrode, a separator, and an electrolyte, without a battery management and protection unit. A battery refers to a battery unit in which a battery cell, after being equipped with a battery protection unit, can normally monitor battery parameters and battery status, and perform control and management. In this embodiment, the battery may be a lithium battery. Step 2: Calculate the target control temperature T2 of the battery during the constant voltage charging phase. The formula for calculating the target control temperature is: , This is a trade-off parameter between charging speed and cell temperature, where 0 < < , This refers to the current charging ambient temperature. Step 3: When the battery is in the constant voltage charging stage, the temperature of the cell is controlled so that the cell temperature T satisfies the following relationship: T2≤T≤T1. The highest temperature during actual charging typically occurs in the constant current phase. This is because during high-rate charging, the heat generated by the battery cell is primarily irreversible heat, also known as ohmic heat, which is proportional to the square of the current. In the constant current phase, the current is relatively high, but after entering the constant voltage phase, the current rapidly decreases, and heat generation also decreases rapidly. Therefore, the highest battery cell temperature occurs during the high-current constant current phase or at the end of the constant current phase. Thus, step three only requires controlling the battery cell temperature to be greater than or equal to the target control temperature. Furthermore, temperature control of the battery cell is implemented, specifically by heating the battery cell. In one specific embodiment, an external current can be used to energize a heating element, which generates Joule heat to heat the battery cell. The heating element can be placed in the battery compartment. It is understood that heat generated by the device containing the battery can also be conducted to the battery cell for heating, such as in a mobile phone. Furthermore, the battery charging method also includes: stopping charging when the battery charging current drops to a first preset value; or stopping charging when the charging capacity of the battery cell reaches a second preset value. Further explanation of the principles of the present invention: The charging method of this invention is identical to the traditional constant current and constant voltage charging method during the constant current charging process. Without heating the battery cell, a constant current is used to charge the battery cell until the terminal voltage reaches a preset value. When the battery cell enters the constant voltage charging stage, the highest temperature of the battery cell at the time of switching to the constant voltage stage is recorded, and the temperature of the battery cell is simultaneously controlled. By controlling the heating current, the temperature of the battery cell is controlled to be near the target temperature value, or between the highest temperature of the battery cell during the constant voltage stage and the target temperature value. Once the battery cell's charging capacity or current drops to a level sufficient for full charging, charging and heating of the battery cell should cease. For example... Figure 2-5 As shown, compared with traditional constant current and constant voltage charging, this charging method results in higher cell temperature, reduced polarization, increased charging current and charging speed, shorter constant voltage charging time, and unchanged charging capacity during the constant voltage charging stage. Since this method does not intervene in the constant current charging stage, it can be used in conjunction with existing constant current / constant voltage / multi-step constant current plus constant voltage methods. It fully utilizes the charging potential of the cell during the constant current stage by employing multi-step constant current charging, and maintains a suitable cell temperature during the constant voltage charging stage to further maximize the cell's charging potential. Because the greatest risk of lithium plating occurs at the end of the constant current charging process, and the cell is not heated at this point, it does not affect the cell's lithium plating performance. This embodiment also discloses a battery charging system, including a constant current charging stage and a constant voltage charging stage. The battery charging system includes: The acquisition module is used to acquire the highest temperature T1 during the constant current charging phase. The calculation module is used to calculate the target control temperature T2 of the battery during the constant voltage charging phase. The formula for calculating the target control temperature is: , This is a trade-off parameter between charging speed and cell temperature, where 0 < < , This refers to the current charging ambient temperature. The control module is used to control the temperature of the battery cell when the battery is in the constant voltage charging stage, so that the temperature T of the battery cell satisfies the following relationship: T2≤T≤T1. In this embodiment, the control module includes: The control unit is used to heat the battery cells. Furthermore, the battery charging system also includes: The first charging control module is used to control the charging system to stop charging the battery when the battery charging current drops to a first preset value. Furthermore, the battery charging system also includes: The second charging control module is used to control the charging system to stop charging the battery when the charging capacity of the battery cell reaches a second preset value. The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other. This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A battery charging method, comprising a constant current charging stage and a constant voltage charging stage, characterized in that, The battery charging method includes: Obtain the highest temperature during the constant current charging phase. ; Calculate the target control temperature of the battery during the constant voltage charging phase. The formula for calculating the target control temperature is: , This is a trade-off parameter between charging speed and cell temperature, where 0 < < , The current charging ambient temperature; When the battery is in the constant voltage charging stage, the temperature of the battery cell is controlled so that the temperature T of the battery cell satisfies the following relationship: ≤ ≤ .

2. The battery charging method according to claim 1, characterized in that, The constant current charging stage is the stage in which the battery cell begins charging at any state of charge.

3. The battery charging method according to claim 1, characterized in that, Temperature control of the battery cell is specifically achieved by heating the battery cell.

4. The battery charging method according to claim 1, characterized in that, The battery charging method further includes: Charging stops when the battery charging current drops to the first preset value.

5. The battery charging method according to claim 1, characterized in that, The battery charging method further includes: Charging stops when the battery cell's charging capacity reaches a second preset value.

6. A battery charging system, comprising a constant current charging stage and a constant voltage charging stage, characterized in that, The battery charging system includes: The acquisition module is used to acquire the highest temperature during the constant current charging phase. ; The calculation module is used to calculate the target control temperature of the battery during the constant voltage charging phase. The formula for calculating the target control temperature is: , This is a trade-off parameter between charging speed and cell temperature, where 0 < < , The current charging ambient temperature; The control module is used to control the temperature of the battery cell when the battery is in the constant voltage charging stage, so that the temperature T of the battery cell satisfies the following relationship: ≤ ≤ .

7. The battery charging system according to claim 6, characterized in that, The control module includes: A control unit is used to heat the battery cell.

8. The battery charging system according to claim 6, characterized in that, The battery charging system also includes: The first charging control module is used to control the charging system to stop charging the battery when the battery charging current drops to a first preset value.

9. The battery charging system according to claim 6, characterized in that, The battery charging system also includes: The second charging control module is used to control the charging system to stop charging the battery when the charging capacity of the battery cell reaches a second preset value.

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