CN102231551A - Battery charger combining charging time and service life of battery - Google Patents

Abstract

The invention relates to a battery charger that takes both charging time and battery life into account, including a main controller, a charging control circuit, a voltage acquisition module, a current acquisition module, a temperature detection module, a protection circuit module, a working state indication module, a display module, and a power supply Conversion module, the main controller is respectively connected with the charging control circuit, voltage acquisition module, current acquisition module, temperature detection module, protection circuit module, working status indication module, display module, the charging control circuit, voltage acquisition module , a current acquisition module, and a temperature detection module are respectively connected to the battery to be charged, and a human-computer interaction module connected to the main controller is also included. Compared with the prior art, the present invention has the advantages that the user can customize the charging time and can reduce battery aging and prolong the battery life by adjusting the charging rate under the condition of a long charging time.

Description

A battery charger that balances charge time and battery life

technical field

The invention relates to a battery charger, in particular to a battery charger which takes both charging time and battery life into consideration.

Background technique

With the rapid development of science and technology, secondary batteries are widely used in various fields. The ability of a battery to actually store power is an important parameter to measure battery performance. For the same battery (group), there is a great correlation between the power that can be released and the power that can be charged, so the power charged is a measure of battery life. An important indicator, in order to ensure the normal operation of the device for a long time, the battery needs to store enough power, which requires charging as much power as possible within the time allowed by charging; secondly, the service life of the battery is also a crucial It is of great significance to reduce the cost of equipment and protect the environment to maximize battery life. Under the same environmental conditions, the charging speed of the battery is determined by the charging rate. The larger the charging rate, the faster the charging speed, that is, the shorter the charging time, but there is a great negative correlation between the battery life and the charging rate. The larger the charging rate, the shorter the battery life, and vice versa, the longer the battery life.

The charger is a special device for supplementing battery energy, but the chargers currently on the market can only charge according to the default setting mode. The shortcomings of this type of charger can be summarized as follows: (1) Users cannot set The charging time, the charging process cannot be controlled, and the charging speed cannot be adjusted; (2) The charger charges according to a fixed charging rate, and the effect of the charging rate on battery aging is a fixed value. The controller cannot achieve the function of reducing battery aging and prolonging battery life by adjusting the charging rate. Therefore, a battery charger that takes both charging time and battery life into account has good practical value and broad market prospects.

Contents of the invention

The object of the present invention is to provide a battery charger that takes both charging time and battery life into account in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

A battery charger that takes both charging time and battery life into account, including a main controller, a charging control circuit, a voltage acquisition module, a current acquisition module, a temperature detection module, a protection circuit module, a working status indication module, a display module, and a power conversion module. The main controller is respectively connected with the charging control circuit, the voltage acquisition module, the current acquisition module, the temperature detection module, the protection circuit module, the working status indication module, and the display module. The charging control circuit, the voltage acquisition module, the current acquisition module The module and the temperature detection module are respectively connected to the battery to be charged, and it is characterized in that it also includes a human-computer interaction module connected to the main controller;

The main controller confirms whether the working mode is the user-defined charging time mode or the system default mode according to the input of the human-computer interaction module;

If it is a user-defined charging time mode, the human-computer interaction module sends the charging time information input by the user to the main controller, and the main controller combines the voltage acquisition module, current acquisition module and temperature detection module according to the received charging time information. Dynamically collected battery parameters, determine the charging state of the battery, calculate the appropriate charging rate, and then charge the battery through the charging control circuit;

If it is the system default mode, the charging task will be completed according to the default mode, and in this mode, the user can set the charging time at any time through the human-computer interaction module. After the user-defined charging time is set, the main controller will set The working mode is switched from the system default mode to the user-defined charging time mode.

The voltage collection module collects the battery voltage, the current collection module collects the charging current, the temperature detection module collects the battery temperature, and the main controller controls the sampling frequency of voltage, current and temperature to detect the battery state in real time.

The human-computer interaction module includes a keyboard, and the input of the set time is realized through the keyboard.

The steps for calculating the appropriate charging rate are as follows:

(1) First calculate the actual rated capacity of the battery;

(2) Then calculate the power stored in the battery at present;

(3) According to the actual rated capacity, calculate the amount of electricity that needs to be charged in the pre-charging stage, constant current stage, and constant voltage stage;

(4) Finally, calculate and determine the constant current charging rate.

Compared with the prior art, the present invention has the ability to realize the user-defined setting of the charging time, that is, to charge as much electricity as possible within the time required by the user under the condition of ensuring the safety of the battery, or to adjust the charging time as time permits. The charging rate realizes the function of reducing battery aging and prolonging battery life.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the general flowchart of the present invention;

Fig. 3 is a flow chart of the charging process of the present invention;

Fig. 4 is a flow chart of the user-defined charging time mode program of the present invention;

Fig. 5 is a schematic diagram of the relationship between voltage, capacity and temperate zone stored in the charger according to the present invention;

Fig. 6 is a calculation flow of the charging rate in the user-defined charging time mode of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example

As shown in Figure 1, a battery charger that takes into account charging time and battery life includes a main controller 1, a charging control circuit 2, a voltage acquisition module 3, a current acquisition module 4, a temperature detection module 5, a protection circuit module 6, Working state indication module 7, display module 8, power conversion module 9, described main controller 1 and charging control circuit 2, voltage acquisition module 3, current acquisition module 4, temperature detection module 5, protection circuit module 6, working The state indication module 7 and the display module 8 are connected, and the charging control circuit 2, the voltage acquisition module 3, the current acquisition module 4, and the temperature detection module 5 are respectively connected with the battery to be charged, and also include the human-computer interaction connected with the main controller Module 10;

The main controller 1 confirms whether the working mode is the user-defined charging time mode or the system default mode according to the input of the human-computer interaction module 10;

If it is a user-defined charging time mode, the human-computer interaction module 10 sends the charging time information input by the user to the main controller 1, and the main controller 1 combines the voltage acquisition module 3 and the current acquisition module according to the received charging time information. 4 and the battery parameters dynamically collected by the temperature detection module 5, determine the charging state of the battery, calculate a suitable charging rate, and then charge the battery through the charging control circuit 2;

If it is the system default mode, the charging task will be completed according to the default mode, and in this mode, the user can set the charging time through the human-computer interaction module at any time. After the user-defined charging time is set, the main controller 1 will Switch the working mode from the system default mode to the user-defined charging time mode.

The charger also has the functions of battery performance detection, battery failure prompt, dynamic adjustment of charging current according to battery temperature, and automatic power-off protection.

The main controller 1 of the charger can choose single-chip microcomputer/DSP/MCU/MPU etc. to realize the control, and according to the difference of the selected controller, the corresponding hardware circuit needs to be changed correspondingly.

The voltage acquisition module 3 and the current acquisition module 4 can be realized by an AD converter or a microprocessor with an AD function. According to different sampling accuracy requirements, it is necessary to select a suitable AD converter or microprocessor. The sampling frequency can be controlled by the charger. Main controller 1 setting.

The temperature detection module 5 can be composed of a temperature sensor or a thermistor and a corresponding circuit, and the temperature sampling frequency is set by the charger main controller 1 to realize real-time monitoring of the battery temperature.

The human-computer interaction module 10 can be composed of circuits such as buttons or a touch screen, and the function of setting time by the user can be realized through this module.

The main controller 1 determines the state of the battery through the charging time value set by the user, combined with the dynamic data collected by the voltage acquisition module 3, current acquisition module 4, and temperature detection module 5, and calculates an appropriate charging rate. According to the charging control The circuit realizes the controllable control of the charging voltage and charging current of the battery, that is, different charging voltages and corresponding changes of the charging current can be realized according to different charging modes of the battery. The countdown function of the charging time of the battery is realized through the timing module, and then the information is dynamically presented through the display module 8 .

This embodiment takes lithium-ion batteries as an example for detailed description, but the present invention is not limited to lithium-ion batteries. Personnel in the relevant technical field can easily refer to this embodiment to make corresponding modifications and optimizations according to different types of battery characteristics. .

The overall process of the present invention is shown in Figure 2. After the system is powered on and initialized, the working state of the charger is first judged. There are four working states (which can be increased or simplified according to specific actual needs): the connected battery needs to be charged, connected The battery is fully charged, the battery is faulty, and the battery is not connected, the system automatically selects different working modes according to different battery states:

(1) If the battery needs to be charged, first judge the initial charging mode of the battery according to the battery voltage, that is, start charging by pre-charging, constant current, or constant voltage, and complete the charging task according to the set charging sequence. After charging, the system automatically Disconnect the charging circuit to prevent battery damage caused by overcharging.

(2) If the battery is fully charged, it will display the message that the battery is fully charged, and automatically disconnect the charging circuit.

(3) If the battery is faulty, the battery fault information will be displayed and the charging circuit will be automatically disconnected.

(4) If no battery is connected, no information will be displayed, and all circuits will be automatically disconnected to save energy.

Figure 3 is a flow chart of the complete charging process. The complete charging process is divided into three consecutive stages, namely trickle pre-charging mode, constant current charging mode, and constant voltage charging mode. Firstly, the current battery voltage V _BAT is detected, and when it is lower than the low voltage threshold V _MIN , trickle precharging starts with a small current I _YC (generally about 1% of the constant current I _HL ). After the battery voltage rises to V _MIN , the charging mode is converted to constant current charging, and the current is I _HL . At this time, the current is relatively large, which is the main stage of charging. In the constant current charging stage, the battery voltage increases with a relatively large slope. When the battery voltage reaches the charging limit voltage V _MAX , it turns into a constant voltage charging mode (charging voltage is V _MAX ), and the charging current I _BAT keeps decreasing. When it drops to a lower limit value I _FULL (generally about 1% of I _HL ), the charging is terminated, and the battery voltage remains basically unchanged during this process. Among them, V _MIN , I _HL , V _MAX , I _YC , and I _FULL parameters can be adjusted and changed according to different batteries.

Depending on the power status of the connected battery, the charging mode may only include the second and third stages (constant current and constant voltage stages) or only the third stage (constant voltage stage). The specific judgment conditions are as follows:

(1) To start battery charging, the following conditions must be met: the battery temperature detection value satisfies T _MIN ≤ T _BAT ≤ T _MAX (T _MIN and T _MAX are the minimum temperature and maximum temperature of the battery charging state, respectively).

(2) When V _BAT < V _MIN , start trickle pre-charging and use a small charging current (for example, I _YC =0.01×I _HL is preferable).

(3) When V _MIN ≤ V _BAT < V _MAX , start constant current charging.

(4) When V _BAT ≥ V _MAX , start constant voltage charging, the charging current I _BAT will gradually decrease, and when it decreases to I _FULL , the charging circuit will be automatically disconnected to prevent damage to the battery due to overcharging, and realize energy saving accordingly energy purpose.

Fig. 4 is a program flow chart of the user-defined charging time mode of the present invention. The charger of the present invention can work in two modes: user-defined charging time charging mode and system default charging mode.

(1) If the user does not set the charging time, the charger will charge the battery according to the system's default charging process and charging rate, and in this mode, the user can set the charging time at any time, and then the charger will work at the user's In custom charging time mode;

(2) After the user sets the charging time, the system calculates the appropriate charging rate by combining the set time value with the currently collected dynamic battery parameters, and then adjusts the battery charging mode to charge the battery.

Figure 5 is a schematic diagram of the relationship between battery capacity, voltage, and temperature. This relationship diagram is stored in the chip of the charger in the form of a numerical table. The main controller of the charger obtains the open circuit voltage (OCV) of the battery through the voltage detection module and the temperature detection module respectively. ) and the current temperature, and then obtain the matching battery capacity information by looking up the table, and calculate the required information in combination with the time and other parameters set by the user.

The relationship between battery capacity, voltage, and temperature can be determined by experiment: take a certain type of battery as a sample body (the more samples, the higher the accuracy of the result), and charge the selected battery repeatedly at different temperatures Discharge, measure the capacity, voltage and temperature relationship curve of each battery, and then get the capacity, voltage and temperature relationship curve of this type of battery through the average value. For users with different display accuracy requirements, the density of test points can be adjusted appropriately (for example, the accuracy can be selected as 1%, 5%, or 10% of the battery capacity, etc.), and the temperature interval value also needs to be divided according to different accuracy requirements. In the schematic diagram, only Data at T1, T2 temperatures are given.

FIG. 6 is a flow chart of charging rate calculation in the user-defined charging time mode of the present invention. The steps of calculating the appropriate charging rate according to the set charging time are as follows:

(1) First calculate the actual rated capacity of the battery;

The detection method of the actual battery capacity is: after the system connects the battery, firstly, test whether the current voltage is the calibrated voltage value, if so, write down the voltage value, if not, charge or discharge the battery (if the connected The battery has been fully charged, then the measured capacity needs to be calculated by discharging), and continue to monitor the battery voltage until a calibrated voltage value, set the voltage value as V1, and this time is t1. The same method is used to find the second voltage calibration point V2, the time is t2, and the battery capacity percentage P1 when the battery voltage is V1 and the capacity percentage P2 when the battery voltage is V2 are obtained by looking up the table. The charging/discharging capacity C _bd during this period is the product of the current and time during this period, then the actual capacity of the battery is:

C＝C _bd /(P2-P1)

in:

When the battery is in precharge or constant current charge mode:

C _bd ＝I*t ＝I*(t2-t1) I is the charging current

When the battery is in constant voltage charging mode:

$C_{\mathrm{bd}}={\&Integral;}_0^{t}f\left(t\right)\mathrm{Idt}={\&Integral;}_{t_1}^{t_2}f\left(t\right)\mathrm{Idt}$ f(t) is the charging coefficient

(2) Then calculate the electric quantity Ce stored in the current battery;

The calculation method of Ce is: after charging starts, first test whether the current voltage is the calibrated voltage value, if so, write down the voltage value, if not, charge the battery, and continue to monitor the battery voltage until a calibrated voltage value, set This voltage value is V1 at time t1. The same method finds the second voltage calibration point V2, time t2, and obtains the battery capacity percentage P1 when the battery voltage is V1, and the capacity percentage P2 when the battery voltage is V2 by looking up the table. The charging/discharging capacity C _bd during this period is the product of the current and time during this period, then the current capacity of the battery is:

Ce＝C _bd *P1/(P2-P1)

Where: when the battery is in precharge or constant current charging mode:

C _bd ＝I*t ＝I*(t2-t1) I is the charging current

When the battery is in constant voltage charging mode:

$C_{\mathrm{bd}}={\&Integral;}_0^{t}f\left(t\right)\mathrm{Idt}={\&Integral;}_{t_1}^{t_2}f\left(t\right)\mathrm{Idt}$ f(t) is the charging coefficient

The current value in the trickle pre-charging stage and the constant-current charging stage is constant, and it is very convenient to calculate the charged power C _bd , which is the product of the charging current I and the charging time t. In the constant voltage charging stage, the battery current gradually decreases as the charging time increases. To estimate a more accurate charging capacity, the integral method can be used. During the period from the start of charging to the end of charging, each time point The current value above can be integrated with time to get a very accurate charging capacity. Therefore, the charging capacity of the battery at this stage can be calculated according to the following formula:

$\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; Idt</span>}$

Where:, f(t) is the charging coefficient, and t3 is the charging time.

This method requires the hardware system to have an integral function. In order to simplify the hardware design of the charger, the charger can also omit the integral circuit and use a discrete mathematical calculation method to estimate the charging power, so the above formula can be recorded as:

$\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; )</span>$

In the formula: I is the charging instantaneous current, Δt is the sampling interval, n is the number of samples, the greater the number of samples, the higher the accuracy of the estimated value.

So the charge into the battery can be expressed as:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ch</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; Idt</span>}$

or: $C_{\mathrm{ch}}=I1*t1+I2*t2+\underset{0}{\overset{\mathrm{no}}{\mathrm{\&Sigma;}}}(I*\mathrm{\&Delta;t})$

(3) According to the actual rated capacity, calculate the amount of electricity that needs to be charged in the pre-charging stage, constant current stage, and constant voltage stage:

Assume that the maximum capacity percentages of the battery corresponding to the pre-charging stage, constant-current stage, and constant-voltage stage set by the system are P _YC , P _HL , and P _HY . , the capacity percentage of the battery at the beginning of charging is P, and the actual capacity of the battery is C, then

If P≤P _YC , then:

C1=C*(P _YC -P)

C2＝C*(P _HL -P _YC )

C3＝C*(P _HY -P _HL )

If P _YC <P≤P _HL , then:

C1=0

C2=C*(P _HL -P)

C3＝C*(P _HY -P _HL )

If P _HL <P≤P _HY , then:

C1=0

C2=0

C3＝C*(P _HY -P)

(4) Final calculation to determine the charging rate

Assuming that the charging time set by the user is T, the charging time required for the three stages of the battery charging process, the trickle precharge stage, the constant current stage, and the constant voltage stage, are respectively t1, t2, and t3, then:

T=t1+t2+t3

in:

t1=C1/I1 (C1: the amount of electricity to be charged in the trickle pre-charging stage, I1: the trickle charging current, take I1 as a fixed small current or the current of I2*1%, this value must be less than the maximum pre-charging current I _yc );

t2=C2/I2 (C2: the amount of electricity to be charged in the constant current stage, I2: the constant current charging current, which should be less than or equal to the maximum value I _MAX of the safe constant current charging current of the battery);

t3=C3/I3 (C3: the amount of electricity to be charged in the constant voltage stage, I3: the average current for constant voltage charging).

Then the constant current charging double current I2 can be obtained:

I2=C2/(T-C1/I1-C3/I3)

The current value is constant in the trickle pre-charging stage and the constant-current charging stage, and the charging time is equal to the charging capacity C divided by the charging current I. However, in the constant voltage charging stage, the battery current gradually decreases as the charging time increases, and the charging process meets the following conditions:

$\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; Idt</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; I</span>}{<span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}$

dF(t)=f(t)dt

The charging time t3 in the constant voltage stage can be calculated from the above formula, and the battery charging current in each stage can be calculated from it. The designed and calculated charging current is I _CH , and the maximum safe charging current is I _MAX :

If I _CH ≤ I _MAX , then take the constant current charging current as I _CH ;

If I _CH >I _MAX , then take the constant current charging current as I _MAX .

The foregoing is only a specific embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications can also be made without departing from the principle of the present invention. It should be regarded as the protection scope of the present invention.

Claims (4)

1. battery charger of taking into account charging interval and battery life, comprise master controller, charging control circuit, voltage acquisition module, the current acquisition module, temperature detecting module, the protective circuit module, the operating state indicating module, display module, power transfer module, described main controller respectively with charging control circuit, voltage acquisition module, the current acquisition module, temperature detecting module, the protective circuit module, the operating state indicating module, display module connects, described charging control circuit, voltage acquisition module, the current acquisition module, temperature detecting module is connected with pond to be charged respectively, it is characterized in that, also comprise the human-computer interaction module that is connected with main controller;

Described master controller is User Defined charging interval pattern or system default pattern according to the input validation mode of operation of human-computer interaction module;

If User Defined charging interval pattern, human-computer interaction module sends to master controller with the charging interval information of user's input, master controller is according to the charging interval information of receiving, in conjunction with battery parameter by voltage acquisition module, current acquisition module and temperature detecting module dynamic acquisition, determine the charged state of battery, calculate suitable rate of charge, by charging control circuit battery is charged then;

If system default pattern, then finish the charging task according to the pattern of acquiescence, and the user can set the charging interval by human-computer interaction module at any time under this pattern, after the User Defined charging interval, setting was finished, master controller can be a User Defined charging interval pattern by the system default mode switch with mode of operation.

2. a kind of battery charger of taking into account charging interval and battery life according to claim 1, it is characterized in that, described voltage acquisition module is gathered cell voltage, the current acquisition module is gathered charging current, temperature detecting module is gathered battery temperature, main controller controls voltage, electric current, temperature sampling frequency play the effect of real-time detection battery status.

3. a kind of battery charger of taking into account charging interval and battery life according to claim 1 is characterized in that described human-computer interaction module comprises keyboard, realizes the input of setting-up time by keyboard.

4. a kind of battery charger of taking into account charging interval and battery life according to claim 1 is characterized in that, described to calculate suitable rate of charge step as follows:

(1) the real account constant volume of counting cell at first;

(2) calculate the electric weight that current battery is stored then;

(3) calculate the electric weight that the needs of preliminary filling stage, constant-current phase, constant-voltage phase charge into respectively according to the real account constant volume;

(4) calculate definite constant current charge multiplying power at last.

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