Nickel-metal hydride battery charging method based on temperature proportion speed reduction

Abstract

The invention discloses a nickel-metal hydride battery charging method based on temperature proportion speed reduction, and the method comprises the following steps: S1, initializing hardware and parameters, and obtaining a current environment temperature, a battery temperature and a battery state; s2, setting charging parameters, wherein the charging parameters comprise an initial charging current, a temperature wall temperature and a current deceleration proportion parameter; s3, acquiring the battery temperature and the battery state in real time, and reducing the charging current for multiple times by adopting a proportional deceleration strategy until a charging cut-off judgment condition is triggered; and S4, finishing charging. In the charging process, the charging current in each stage is gradually reduced according to the set proportion until the battery charging is finished, so that the energy received by the battery is ensured to be saturated, and meanwhile, the influence of overhigh temperature on the service life of the battery is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of battery charging, and in particular to a nickel-hydrogen battery charging method based on temperature proportional speed reduction. Background Art

[0002] For the fast charging management of NiMH batteries, constant current charging is currently commonly used. Since the voltage of NiMH batteries does not change linearly with the amount of electricity, and is greatly affected by temperature and charging circuit and has no specific full-charge voltage, the temperature rise per unit time (dT / dt) and a slight drop in voltage when fully charged (-dV) are often used as the way to determine whether the battery is fully charged.

[0003] The above-mentioned methods for determining the charging of NiMH batteries all require a good heat dissipation environment, or there is no obvious heat source near the battery; NiMH batteries cannot be fully charged when charging is near the end, and the excess energy will be dissipated in the form of heat, causing temperature rise. In devices with poor heat dissipation, the battery temperature will rise rapidly due to the above-mentioned influence, resulting in a decrease in the battery charging efficiency, failure to fully charge the battery normally, or even damage to the battery, reducing the battery life. Summary of the invention

[0004] The purpose of the present invention is to provide a nickel-hydrogen battery charging method based on temperature proportional speed reduction to solve the problem of how to increase the battery life.

[0005] The present invention is implemented by adopting the following technical scheme: a nickel-hydrogen battery charging method based on temperature proportional speed reduction, comprising the following steps: S1: Initialize hardware and parameters, and obtain current ambient temperature, battery temperature, and battery status; S2: Setting charging parameters, which include initial charging current, temperature of the temperature wall and current deceleration ratio parameters; S3: Obtain the battery temperature and battery status in real time, adopt a proportional deceleration strategy, and reduce the charging current multiple times until the charging cut-off judgment condition is triggered; S4: End charging.

[0006] Furthermore, step S1 is specifically as follows: obtaining the ambient temperature and the battery temperature through the temperature acquisition device; and obtaining the battery status, including the battery voltage, through the power conversion device.

[0007] Furthermore, the initial charging current is set according to the ambient temperature. When the ambient temperature is lower than a preset value, charging is performed with a large current parameter; when the ambient temperature is higher than a preset value, charging is performed with a small current parameter.

[0008] Furthermore, the temperature wall temperature is a control trigger condition during the charging process, which is specifically set by ambient temperature or fixed temperature. The setting by ambient temperature is specifically as follows: setting according to the current ambient temperature, taking the current ambient temperature as a reference, and taking a preset fixed temperature rise temperature as a temperature rise condition as the temperature wall temperature; the setting by fixed temperature is specifically as follows: using a fixed temperature value as the temperature wall temperature based on battery parameters.

[0009] Furthermore, the current deceleration ratio parameter ranges from 0.5 to 0.9.

[0010] Furthermore, the proportional deceleration strategy is: in the first charging stage, the battery is quickly charged using the initial current. When the battery temperature reaches the temperature wall temperature, the charging current is reduced according to the current deceleration proportional parameter, and the second charging stage, the third charging stage, ..., the nth charging stage are entered in sequence.

[0011] Furthermore, in the first charging stage, the second charging stage, the third charging stage, ..., the nth charging stage, the charging current of each charging stage is a constant current, and the charging current of the next stage is the charging current of the previous stage multiplied by the current deceleration ratio parameter.

[0012] Furthermore, the current reduction ratio parameter in each charging stage is the same or different.

[0013] Furthermore, the charging cut-off judgment condition includes that the charging speed is lower than a preset value, or the energy charged into the battery reaches a set maximum charging capacity.

[0014] The beneficial effect of the present invention is that during charging, the charging current in each stage is gradually reduced according to a set ratio until the battery charging is completed, thereby ensuring that the energy received by the battery reaches saturation and preventing the impact of excessive temperature on the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0016] Figure 1 It is a flow chart of the present invention; Figure 2 It is the graph of charging current changing with charging time; Figure 3 This is a graph showing the battery temperature changing with charging time. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0018] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0019] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] See also Figure 1 , a method for charging a nickel-hydrogen battery based on temperature proportional speed reduction, comprising the following steps: In the initialization phase, the temperature acquisition device is started to obtain the ambient temperature and the battery temperature; the power conversion device is started to obtain the battery voltage.

[0021] Before charging, set the initial charging current according to the ambient temperature, battery temperature, battery voltage, and status of the charging device obtained during the initialization phase. Set the current according to the ambient temperature. When the ambient temperature is lower than a certain set value (such as 5°C), use a larger current parameter. When the ambient temperature is higher than a certain set value (such as 30°C), use a smaller current parameter.

[0022] The temperature wall temperature is set (the concept of a "temperature wall" is proposed. The temperature wall here is different from the safety measures in other charging methods, but a control trigger condition in the charging process). There are two ways to set the temperature wall temperature. The first is to set it according to the current ambient temperature, with the current ambient temperature as the benchmark and a fixed temperature rise temperature (such as 25°C) as the temperature rise condition as the temperature wall temperature; the second is to use a fixed temperature value as the temperature wall temperature based on battery parameters.

[0023] Set the current speed reduction ratio parameter (typical range: 0.5~0.9).

[0024] During the charging process, the battery temperature, voltage and current are monitored in real time. In the first charging stage, the initial current is used to quickly charge the battery. When the battery temperature touches the temperature wall temperature, the charging current is reduced according to the current reduction ratio parameter, and the second charging stage, the third charging stage, ..., the nth charging stage are entered in sequence. The above process is repeated until the cut-off judgment condition is triggered. The charging current changes with charging time as shown in the figure below: Figure 2As shown; the battery temperature changes with charging time as shown Figure 3 shown.

[0025] At the end of charging, when the charging speed is lower than a certain set value, the battery voltage drops to a threshold value, or reaches the set maximum charging capacity, it is the charging cut-off judgment condition; after the judgment condition is triggered, charging stops and enters the standby state, and charging ends.

[0026] The present invention also provides a charging system, the hardware architecture of which should at least be composed of a battery pack, a temperature acquisition device, a power conversion device, and a main controller. The battery pack is a battery combination composed of a single nickel-hydrogen battery or multiple nickel-hydrogen batteries connected in series, in parallel, etc. The temperature acquisition device includes a temperature-sensitive temperature-variable device, whose own characteristics change with temperature. The temperature-sensitive device has a relatively wide range of temperature perception capabilities and needs to have a good linear change relationship within the perception range. The device collects the voltage change output of the temperature-sensitive device according to the temperature change, and at the same time, the device performs preliminary processing on the collected data. The power conversion device is a power converter, and the topology has the ability of bidirectional power conversion, including boost conversion and buck conversion. The power converter can realize a constant current output with real-time adjustable current; in order to minimize the heating phenomenon of the battery during the charging process, the output of this power converter has a lower ripple. The main controller is a control system constructed by a single-chip microcomputer, an embedded system or other programmable system, which can read the temperature data collected by the temperature acquisition device and control the output power of the power conversion device in real time according to the collected temperature data.

[0027] The charging method of the charging system is: according to the initial state of the battery, the ambient temperature and the state of the charging device, the charging current of the battery in the first charging stage is set, and the battery is charged with a constant current in stages using a current based on a preset speed reduction ratio; wherein the charging process of the battery includes the first charging stage, the second charging stage, the third charging stage, the fourth charging stage... the nth stage in sequence, and the charging current of the first charging stage> the charging current of the second charging stage> the charging current of the third charging stage> the charging current of the fourth charging stage>...> the charging current of the nth charging stage. wherein the charging current of the nth charging stage=the charging current of the n-1th charging stage*the current speed reduction ratio parameter. The current reduction ratio parameter is a parameter for adjusting the charging current reduction rate after the battery temperature reaches the temperature wall temperature during the charging process (typical range: 0.5-0.9). For example, in each stage, the current reduction ratio parameter is set to 0.8; or the current reduction ratio parameter is set to 0.9 in the first charging stage, and the current reduction ratio parameter is set to 0.8 in the second charging stage, etc. Technical personnel in this field can set the current reduction ratio parameter for each charging stage according to actual conditions, and the present application may not limit the specific setting of the current reduction ratio parameter for each charging stage.

[0028] The present invention uses battery temperature as the main control parameter during the battery charging process to switch the battery charging stage according to the temperature of the charged battery; the charging stage has at least 3 stages, and the specific number of stages is adjusted and controlled according to the battery state and the speed reduction ratio parameter.

[0029] The charging current of the present invention is the current for charging the battery, and the energy is provided by the power conversion device; in the charging stage, the charging current of the battery is a constant current, and is regulated by closed-loop control; the current is regulated according to the speed reduction ratio parameter in each stage, that is, the current in the next stage is the current in the previous stage * the speed reduction ratio parameter; in each stage, the current is gradually reduced according to the set parameter ratio, and the charging current is constant in each stage. The charging current in each stage of the present invention is gradually reduced according to the set ratio until the battery charging is completed, so as to ensure that the energy received by the battery reaches saturation, and at the same time, prevent the influence of excessive temperature on the battery life.

[0030] For the aforementioned embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily required by the present application.

[0031] The above embodiments describe the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the changes and modifications made by those skilled in the art shall be within the scope of protection of the appended claims of the present invention without departing from the spirit and scope of the present invention.

Claims

1. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction, characterized in that: The steps include: S1: Initialize hardware and parameters, and obtain current ambient temperature, battery temperature, and battery status; S2: Setting charging parameters, which include initial charging current, temperature of the temperature wall and current deceleration ratio parameters; S3: Obtain the battery temperature and battery status in real time, adopt a proportional deceleration strategy, and reduce the charging current multiple times until the charging cut-off judgment condition is triggered; S4: End charging.

2. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction as claimed in claim 1, characterized in that: Step S1 specifically includes: obtaining the ambient temperature and the battery temperature through a temperature acquisition device; and obtaining the battery status, including the battery voltage, through a power conversion device.

3. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction as claimed in claim 2, characterized in that: The initial charging current is set according to the ambient temperature. When the ambient temperature is lower than a preset value, a large current parameter is used for charging; when the ambient temperature is higher than a preset value, a small current parameter is used for charging.

4. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction as claimed in claim 3, characterized in that: The temperature wall temperature is a control trigger condition during the charging process, which is specifically set by ambient temperature or fixed temperature. The setting by ambient temperature is specifically as follows: setting according to the current ambient temperature, taking the current ambient temperature as a reference, and taking a preset fixed temperature rise temperature as a temperature rise condition as the temperature wall temperature; the setting by fixed temperature is specifically as follows: using a fixed temperature value as the temperature wall temperature based on battery parameters.

5. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction as claimed in claim 4, characterized in that: The current deceleration ratio parameter ranges from 0.5 to 0.

9.

6. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction as claimed in claim 5, characterized in that: The proportional deceleration strategy is: in the first charging stage, the battery is quickly charged using the initial current. When the battery temperature reaches the temperature wall temperature, the charging current is reduced according to the current deceleration proportional parameter, and the second charging stage, the third charging stage, ..., and the nth charging stage are entered in sequence.

7. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction as claimed in claim 6, characterized in that: In the first charging stage, the second charging stage, the third charging stage, ..., and the nth charging stage, the charging current of each charging stage is a constant current, and the charging current of the next stage is the charging current of the previous stage multiplied by the current deceleration ratio parameter.

8. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction as claimed in claim 7, characterized in that: The current reduction ratio parameters in each charging stage are the same or different.

9. A method for charging a nickel-hydrogen battery based on temperature proportional speed reduction as claimed in claim 8, characterized in that: The charging cut-off judgment condition includes that the charging speed is lower than a preset value, or the energy charged into the battery reaches a set maximum charging capacity.

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