CN202749879U

CN202749879U - Charging circuit for lithium battery

Info

Publication number: CN202749879U
Application number: CN201220486655.0U
Authority: CN
Inventors: 陈会甫
Original assignee: NINGBO HANPU TOOLS CO Ltd
Current assignee: NINGBO HANPU TOOLS CO Ltd
Priority date: 2012-09-24
Filing date: 2012-09-24
Publication date: 2013-02-20
Anticipated expiration: 2022-09-24

Abstract

The utility model discloses a charging circuit for a lithium battery. The charging circuit comprises a temperature sensor (1), an A/D conversion unit (2), an MCU (3), a PWM output unit (4), a comparison unit (5), a feedback unit (6), a PWM modulation unit (7) and a voltage output unit (8) which are sequentially in electrical connection. Data sampled by the temperature sensor (1) are used to control the PWM modulation unit (7), the output of the voltage output unit (8) is then adjusted, and the purpose of adjusting the value of charging current is achieved. The charging circuit for the lithium battery can automatically adjust the value of the charging current according to the temperature of the lithium battery.

Description

Lithium battery charging circuit

Technical field

The utility model relates to a kind of lithium battery charging circuit.

Background technology

As everyone knows, charging and discharging lithium battery characteristic temperature influence, generally speaking, battery is not allowing charging below 0 degree or more than 60 degree, battery does not allow discharge more than 70 degree, and in the situation that temperature exceeds and very lowly can not use large current charge very much, otherwise can shorten battery, the lithium battery charging circuit of prior art can't be adjusted charging current value automatically according to the temperature of lithium battery, the excessive situation of charging current value when easily the generation battery temperature is too high or too low, long-term in this case charging can be shortened the useful life of battery greatly.

The utility model content

Technical problem to be solved in the utility model is that the lithium battery charging circuit that can automatically adjust according to the temperature of lithium battery charging current value is provided.

For solving the problems of the technologies described above, the lithium battery charging circuit that the utility model provides, it comprises the temperature inductor that is electrically connected successively, the A/D converting unit, MCU, the PWM output unit, comparing unit, feedback unit, PWM modulating unit and voltage output unit, temperature inductor is located at the outer surface of lithium battery, the temperature value that is used for the sampling lithium battery, the A/D converting unit is used for the temperature value of sampling is converted to corresponding digital signal, MCU is used for the default charging current value corresponding with temperature value, the PWM output unit is used for digital signal is converted to the pwm signal of corresponding duty ratio, comparing unit is used for pwm signal and fiducial value are compared and export corresponding comparative result, fiducial value is directly proportional with current charging current value, feedback unit is used for comparative result is fed back, and pwm unit and voltage output unit are used for the charging current of control lithium battery.

After adopting above structure, the utility model compared with prior art has advantages of following:

The A/D converting unit is by the current temperature value of temperature inductor sampling lithium battery, MCU default when temperature be 0 ~ 10 when spending, charging current is 300 milliamperes; When temperature is 10 ~ 45 when spending, charging current be 300 milliamperes between 3 peaces, concrete numerical value can be selected according to actual needs; When temperature is 45 ~ 55 when spending, charging current is 300 milliamperes, the PWM output unit is exported the pwm signal of corresponding duty ratio to comparing unit, fiducial value with comparing unit, namely current corresponding charging current value compares, feed back to the PWM modulating unit relatively, the pulse control voltage output unit of PWM modulating unit output respective cycle and duty ratio, regulate the elementary current value of power supply, make charging current corresponding with Current Temperatures, make this lithium battery charging circuit automatically adjust charging current value according to the temperature of lithium battery, avoid that charging current value is excessive when too high or too low that shortened the useful life of lithium battery owing to battery temperature.

As improvement, described A/D converting unit, PWM output unit and MCU are integrated in a single-chip microcomputer, that is to say this single-chip microcomputer with A/D and PWM function, and single-chip microcomputer is provided with A/D input port, PWM output port, uses more convenient.

As further improvement, the model of described single-chip microcomputer is MC80F1504, and MC80F1504 is 8 single-chip microcomputers of CMOS of a kind of 4K of having byte FLASH ROM and 256 byte RAM, in addition, also have 10 ADC and PWM in the sheet, be applicable to the control function of analog signal.

Description of drawings

Fig. 1 is the structured flowchart of the utility model lithium battery charging circuit;

Fig. 2 is the circuit theory diagrams of the utility model lithium battery charging circuit.

Wherein, 1, temperature inductor; 2, A/D converting unit; 3, MCU; 4, PWM output unit; 5, comparing unit; 6, feedback unit; 7, PWM modulating unit; 8, voltage output unit.

Embodiment

Below in conjunction with the drawings and specific embodiments the utility model is described in more detail.

By Fig. 1, shown in Figure 2, the utility model lithium battery charging circuit comprises the temperature inductor 1 that is electrically connected successively, A/D converting unit 2, MCU3, PWM output unit 4, comparing unit 5, feedback unit 6, PWM modulating unit 7 and voltage output unit 8, the probe of temperature inductor 1 sticks at the outer surface of lithium battery, the temperature value that is used for the sampling lithium battery, A/D converting unit 2 is used for the temperature value of sampling is converted to corresponding digital signal, MCU3 is used for the default charging current value corresponding with temperature value, such as presetting 10～45 when spending, charging current is 2 peaces, 0～10 degree, 45～55 when spending, charging current is 300 milliamperes, PWM output unit 4 is used for digital signal is converted to the pwm signal of corresponding duty ratio, comparing unit 5 is used for pwm signal and fiducial value are compared and export corresponding comparative result, fiducial value is the as shown in Figure 2 pressure drop on the R9 namely, it is directly proportional with the voltage of lithium battery, feedback unit 6 is used for comparative result is fed back to PWM modulating unit 7, the pulse control voltage output unit 8 of PWM modulating unit 7 output respective cycle and duty ratio, regulate the elementary current value of power supply, the charging current of control lithium battery.

A/D converting unit 2 is by the current temperature value of temperature inductor 1 sampling lithium battery, MCU3 default when temperature be 0 ~ 10 when spending, charging current is 300 milliamperes; When temperature is 10 ~ 45 when spending, charging current be 300 milliamperes between 3 peaces, concrete numerical value can be selected according to actual needs; When temperature is 45 ~ 55 when spending, charging current is 300 milliamperes, the pwm signal of the corresponding duty ratio of PWM output unit 4 outputs is to comparing unit 5, fiducial value with comparing unit 5, namely current corresponding charging current value compares, and feeds back to relatively afterwards PWM modulating unit 7, the pulse control voltage output unit 8 of PWM modulating unit 7 output respective cycle and duty ratio, regulate the elementary current value of power supply, make charging current corresponding with Current Temperatures.

Described A/D converting unit 2, PWM output unit 4 and MCU3 are integrated in a single-chip microcomputer, and the single-chip microcomputer model is MC80F1504.

Temperature inductor 1, A/D converting unit 2, MCU3, PWM converting unit 4, comparing unit 5, feedback unit 6, PWM modulating unit 7 and voltage output unit 8 are prior art, concrete circuit structure are not done too much elaboration here.

Below only use better example with regard to the utility model and made explanation, but can not be interpreted as it is limitations on claims, structure of the present utility model can have other variations, is not limited to said structure.In a word, all various variations of doing in the protection range of independent claims of the present utility model are all in protection range of the present utility model.

Claims

1. lithium battery charging circuit, it is characterized in that: it comprises the temperature inductor (1) that is electrically connected successively, A/D converting unit (2), MCU(3), PWM output unit (4), comparing unit (5), feedback unit (6), PWM modulating unit (7) and voltage output unit (8), temperature inductor (1) is located at the outer surface of lithium battery, the temperature value that is used for the sampling lithium battery, A/D converting unit (2) is used for the temperature value of sampling is converted to corresponding digital signal, MCU(3) be used for the default charging current value corresponding with temperature value, PWM output unit (4) is used for digital signal is converted to the pwm signal of corresponding duty ratio, comparing unit (5) is used for pwm signal and fiducial value are compared and export corresponding comparative result, feedback unit (6) is used for comparative result is fed back, and PWM modulating unit (7) and voltage output unit (8) are used for the charging current of control lithium battery.

2. lithium battery charging circuit according to claim 1 is characterized in that: described A/D converting unit (2), PWM converting unit (4) and MCU(3) be integrated in a single-chip microcomputer.

3. lithium battery charging circuit according to claim 2, it is characterized in that: the model of described single-chip microcomputer is MC80F1504.