Constant-temperature charging control method for nickel-metal hydride battery

Abstract

The invention discloses a nickel-metal hydride battery constant-temperature charging control method, which comprises the following steps of S1, initializing hardware and parameters, and acquiring a current environment temperature, a battery temperature and a battery state; s2, setting an initial charging current and a temperature wall temperature by adopting a multi-stage setting strategy; s3, acquiring the battery temperature and the battery state in real time, and realizing constant-current charging and variable-current charging control of the battery by adopting a multi-stage control method; and S4, finishing charging. According to the invention, the battery is charged at a constant temperature, and the temperature of the battery is controlled within the set temperature range of the temperature wall, so that the thermal failure of the battery is avoided, the charging efficiency of the battery in closed equipment and equipment with poor heat dissipation is ensured, and the service life of the battery is prolonged at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of battery charging, and in particular to a constant temperature charging control method for a nickel-hydrogen battery. 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.

[0004] For devices with poor heat dissipation, a new method is needed to ensure that the battery is quickly charged and the battery temperature is controlled to increase the battery life. Summary of the invention

[0005] The purpose of the present invention is to provide a constant temperature charging control method for a nickel-hydrogen battery, so as to solve the problem of rapid charging of the battery under poor heat dissipation conditions.

[0006] The present invention is implemented by adopting the following technical scheme: a constant temperature charging control method for a nickel-hydrogen battery, comprising the following steps: S1: Initialize hardware and parameters, and obtain current ambient temperature, battery temperature, and battery status; S2: Use a multi-stage setting strategy to set the initial charging current and temperature wall temperature; S3: Real-time acquisition of battery temperature and battery status, and use of a multi-stage control method to achieve constant current charging and variable current charging control of the battery; S4: End charging.

[0007] Furthermore, step S1 is specifically as follows: 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.

[0008] Furthermore, the multi-stage setting strategy includes an initial charging current setting and a temperature wall temperature setting, wherein: Initial charging current setting: Set the initial charging current according to the ambient temperature. When the ambient temperature is lower than the preset value, use high current parameters for charging; when the ambient temperature is higher than the preset value, use low current parameters for charging; Temperature wall temperature setting: The temperature wall temperature is the control trigger condition during the charging process. Specifically, the temperature wall temperature is set by ambient temperature or fixed temperature.

[0009] Furthermore, the temperature wall temperature setting includes two methods: first, setting it according to the current ambient temperature, taking the current ambient temperature as the reference and the preset fixed temperature rise as the temperature rise condition as the temperature wall temperature; second, using a fixed temperature value as the temperature wall temperature based on battery parameters.

[0010] Furthermore, the multi-stage control method includes two-stage control. In the first stage, charging is performed by a constant current charging method; in the second stage, charging is performed by a variable current charging method.

[0011] Furthermore, the first stage refers to when the battery temperature has not reached the set temperature wall temperature, constant current charging is performed according to the charging current set by the initial charging current to make the battery temperature reach the temperature wall temperature.

[0012] Furthermore, the second stage refers to when the battery temperature reaches the temperature wall temperature, the charging current is adjusted in real time through the control algorithm to stabilize the battery temperature within a preset range of the temperature wall temperature.

[0013] Furthermore, step S4 is specifically as follows: when the charging speed is lower than a preset value, or the energy charged into the battery reaches a set maximum charging capacity, charging is determined to be terminated, charging is stopped, and the device enters a standby state to complete charging.

[0014] The beneficial effects of the present invention are as follows: the present invention adopts constant temperature charging of the battery to control the temperature of the battery within the set temperature range of the temperature wall, thereby avoiding thermal failure of the battery, ensuring the efficiency of battery charging in closed equipment and equipment with poor heat dissipation, and extending the life of the battery. 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 actual battery temperature changing with charging time; Figure 4 This is a graph showing the change in theoretical battery temperature over 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 constant temperature charging control method for a nickel-hydrogen battery, comprising the following steps: During the initialization phase, the temperature acquisition device is started to obtain the ambient temperature and battery temperature; the power conversion device is started to obtain the battery voltage and the status of the charging device.

[0021] Before charging, set the initial charging current according to the ambient temperature and battery temperature, battery voltage, and the status of the charging device obtained during the initialization phase. Set it according to the ambient temperature. When the ambient temperature is lower than a certain set value, use a larger current parameter. When the ambient temperature is higher than a certain set value, use a smaller current parameter. It can be imagined that the set value of the ambient temperature here can be adjusted according to actual conditions, such as a low temperature threshold of 5°C and a high temperature threshold of 30°C. The present invention does not limit the ambient temperature set value.

[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 certain fixed temperature rise (such as 25°C) as the temperature rise condition as the temperature wall temperature; the second is to use a fixed temperature value (such as 25°C) as the temperature wall temperature based on battery parameters.

[0023] During the charging process, the battery temperature, voltage and current are monitored in real time. In the first stage, the battery temperature has not reached the temperature wall temperature, and constant current charging is used to make the battery temperature reach the temperature wall temperature. In the second stage, when the battery temperature reaches the temperature wall temperature, the control algorithm is used to adjust the charging current in real time to stabilize the battery temperature near the temperature wall temperature, such as adjusting it within 5% of the temperature wall temperature value. This range can be set according to actual conditions and is not limited by the present invention. The change trend of charging current with charging time is shown in the figure below. Figure 2 As shown in the figure, the trend of the actual battery temperature changing with charging time is as follows Figure 3 As shown in Figure 2, the theoretical battery temperature changes with charging time. Figure 4 shown.

[0024] At the end of charging, when the charging speed is lower than a certain set value, or the charged energy 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.

[0025] 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 or in parallel. 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 voltage changes based on the output of the temperature-sensitive device for temperature changes, 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 achieve 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. The system 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.

[0026] It should be pointed out that the charging current in the present invention is the current for charging the battery, which is the energy provided by the power conversion device; in the constant temperature charging stage, the charging current of the battery is a variable current charging method, and the temperature closed loop control is adopted to adjust the battery to keep the battery in a constant temperature state. When the battery temperature does not reach the temperature wall temperature, the charging current is a constant current, and when the battery temperature reaches the temperature wall temperature, it enters the variable current charging state.

[0027] It should also be noted that the constant temperature in the present invention refers to the temperature of the charged battery, including but not limited to the battery surface temperature, the battery radiation temperature, and the battery charging equipment temperature.

[0028] The charging system includes two charging stages, namely stage one and stage two. Stage one uses constant current charging, and the current is mainly set by the battery's own characteristics, ambient temperature, and the state of the charging equipment. In this stage, the battery temperature has not reached the temperature wall temperature. In the later stage of this stage, the energy that can be charged into the battery per unit time decreases, and the excess energy is dissipated in the form of heat energy, causing the battery temperature to rise. When the battery temperature reaches the temperature wall temperature, the battery charging is converted to stage two. By controlling the charging current, the battery is kept in a constant temperature state, that is, in the charging stage, the battery charging current is reduced and fine-tuned in real time through the PID algorithm, so that the battery temperature fluctuates around the preset temperature wall temperature.

[0029] Based on the above embodiments, the present invention has at least the following technical effects: The present invention adopts constant temperature charging of the battery to control the temperature of the battery within a set temperature range of the temperature wall, thereby avoiding thermal failure of the battery, ensuring the efficiency of battery charging in closed equipment and equipment with poor heat dissipation, and extending the life of the battery.

[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 constant temperature charging control method for a nickel-hydrogen battery, characterized in that: The steps include: S1: Initialize hardware and parameters, and obtain current ambient temperature, battery temperature, and battery status; S2: Use a multi-stage setting strategy to set the initial charging current and temperature wall temperature; S3: Real-time acquisition of battery temperature and battery status, and use of a multi-stage control method to achieve constant current charging and variable current charging control of the battery; S4: End charging.

2. A constant temperature charging control method for a nickel-hydrogen battery 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 constant temperature charging control method for a nickel-hydrogen battery as claimed in claim 2, characterized in that: The multi-stage setting strategy includes initial charging current setting and temperature wall temperature setting, wherein: Initial charging current setting: Set the initial charging current according to the ambient temperature. When the ambient temperature is lower than the preset value, use high current parameters for charging; when the ambient temperature is higher than the preset value, use low current parameters for charging; Temperature wall temperature setting: The temperature wall temperature is the control trigger condition during the charging process. Specifically, the temperature wall temperature is set by ambient temperature or fixed temperature.

4. A constant temperature charging control method for a nickel-hydrogen battery as claimed in claim 3, characterized in that: The temperature wall temperature setting includes two methods: first, setting according to the current ambient temperature, taking the current ambient temperature as the reference and the preset fixed temperature rise as the temperature rise condition as the temperature wall temperature; Second, a fixed temperature value is used as the temperature wall temperature based on the battery parameters.

5. A constant temperature charging control method for a nickel-hydrogen battery as claimed in claim 4, characterized in that: The multi-stage control method includes two-stage control. In the first stage, charging is performed by a constant current charging method; in the second stage, charging is performed by a variable current charging method.

6. A constant temperature charging control method for a nickel-hydrogen battery as claimed in claim 5, characterized in that: The first stage refers to when the battery temperature has not reached the set temperature wall temperature, constant current charging is performed according to the charging current set by the initial charging current to make the battery temperature reach the temperature wall temperature.

7. A constant temperature charging control method for a nickel-hydrogen battery as claimed in claim 6, characterized in that: The second stage refers to when the battery temperature reaches the temperature wall temperature, the charging current is adjusted in real time through the control algorithm to stabilize the battery temperature within the preset range of the temperature wall temperature.

8. A constant temperature charging control method for a nickel-hydrogen battery as claimed in claim 7, characterized in that: Step S4 is specifically as follows: when the charging speed is lower than a preset value, or the energy charged into the battery reaches a set maximum charging capacity, charging is determined to be terminated, charging is stopped, and the device enters a standby state to complete charging.

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