A lithium battery pack charging device

Abstract

The present invention provides a lithium battery pack charging device, which belongs to the field of charging devices. The lithium battery pack charging device provided by the present invention has a single-chip computer system, a controllable constant current source, a voltage limiting control circuit and a voltage limiting detection circuit. The single-chip computer reads the voltage value range of the current charged battery, and then converts it into a controllable constant current source circuit module for voltage limiting control through a timer interrupt. When the voltage is too high, the voltage limiting control circuit will automatically limit the maximum voltage and current. The third resistor in the voltage limiting control circuit needs to control the resistance value through the single-chip computer control relay to adjust the voltage limiting value, thereby adjusting and stabilizing the current of the charged battery. Therefore, the lithium battery pack charging device provided by the present invention can charge lithium batteries of different models, and has a simple structure, convenient manufacturing and low cost.

Description

Technical Field

[0001] The invention belongs to the field of charging devices, and in particular relates to a lithium battery pack charging device. Background Art

[0002] As electronic products play an increasingly important role in our lives, their power source - batteries - has also come in a variety of models. For example, the batteries in campus laboratories have a variety of models ranging from 3.7V to 11.1V, of which the largest number is 3.7V lithium batteries. However, different batteries require different battery chargers to charge, and stacking a large number of chargers not only takes up a lot of space but also causes errors. Using the wrong charger to charge a lithium battery pack can easily damage the battery and cause the battery to be scrapped prematurely. However, the prior art does not have a charging device that can charge multiple different models of lithium batteries at the same time. Summary of the invention

[0003] The present invention is made to solve the above-mentioned problem, and its purpose is to provide a lithium battery pack charging device capable of charging lithium batteries of various types.

[0004] The present invention provides a lithium battery pack charging device having the following characteristics, including: a controllable constant current source, having at least one voltage detection point, electrically connected to a charging power supply and a lithium battery pack respectively; a voltage limiting control circuit, electrically connected to the controllable constant current source through the voltage detection point; a single-chip computer system, electrically connected to the controllable constant current source and the voltage limiting control circuit respectively; and a voltage limiting monitoring circuit, electrically connected to the controllable constant current source and the single-chip computer system respectively, wherein the voltage limiting detection circuit is used to detect the voltage of a connection line between the controllable constant current source and the lithium battery pack and to generate a voltage feedback signal and send it to the single-sided machine minimum system, the single-chip computer system sends an output voltage control signal to the voltage limiting control circuit and an output current control signal to the controllable constant current source according to the voltage feedback signal, the voltage limiting control circuit controls the output maximum voltage value of the controllable constant current source according to the output voltage control signal, and the controllable constant current source controls the output current according to the output current control signal.

[0005] The lithium battery pack charging device provided by the present invention may also have the following feature: wherein the controllable constant current source and the voltage limiting control circuit constitute a controllable constant current source circuit module with voltage limiting control.

[0006] In the lithium battery pack charging device provided by the present invention, it can also have the following characteristics: wherein, the controllable constant current source circuit module of the voltage limiting control includes a first triode, a second triode, a field effect tube, a second resistor, a third resistor, a fourth resistor, a voltage input terminal before voltage regulation, a control port, a comparison detection port, a positive electrode interface of the lithium battery pack and a negative electrode interface of the lithium battery pack, the base electrode of the first triode is connected to the control port through the fourth resistor, the base electrode is electrically connected to the gate of the field effect tube, the emitter electrode is connected to the negative electrode interface of the lithium battery pack, the collector of the second triode is connected to the voltage input terminal before voltage regulation through the second resistor, the base electrode is connected to the positive electrode interface of the lithium battery pack through the third resistor, the emitter electrode is connected to the positive electrode interface of the lithium battery pack, the source of the field effect tube is connected to the voltage input terminal before voltage regulation, the drain is connected to the positive electrode interface of the lithium battery pack through the third resistor, a ground terminal is provided on the connecting line between the emitter electrode of the first triode and the negative electrode interface of the lithium battery pack, and a comparison detection port is provided on the connecting line between the emitter electrode of the second triode and the positive electrode interface of the lithium battery pack.

[0007] The lithium battery pack charging device provided by the present invention may also have the following feature: wherein the first transistor and the second transistor are both PNP transistors.

[0008] The lithium battery pack charging device provided by the present invention may also have the following features: wherein the single-chip microcomputer system includes: a single-chip microcomputer; a first resistor, one end of which is connected to the EA / VPP interface of the single-chip microcomputer, and the other end of which is connected to the power supply voltage; a reset circuit, which is respectively connected to the XT1 interface and the XT2 interface of the single-chip microcomputer; and a crystal oscillator circuit, which is connected to the RST interface of the single-chip microcomputer.

[0009] The lithium battery pack charging device provided by the present invention may also have the following features: wherein the reset circuit includes: a first capacitor, a second capacitor and a crystal oscillator, the first capacitor and the second capacitor are connected in series, the crystal oscillator and the first capacitor and the second capacitor are connected in parallel, the two ends of the crystal oscillator are respectively connected to the XT1 interface and the XT2 interface of the microcontroller, and a grounding interface is provided between the first capacitor and the second capacitor.

[0010] The lithium battery pack charging device provided by the present invention may also have the following features: wherein the crystal oscillator circuit includes: an electrolytic capacitor, a tenth resistor and a reset button; the positive electrode of the electrolytic capacitor is connected to the reset button, and the negative electrode is respectively connected to the RST interface of the single-chip microcomputer and the tenth resistor; one side of the reset button is connected to the electrolytic capacitor, and the other side is connected to the tenth resistor and the RST interface of the single-chip microcomputer; one end of the tenth resistor is respectively connected to the reset button and the negative electrode of the electrolytic capacitor, and the other end is grounded; a power supply voltage interface is provided between the electrolytic capacitor and the reset button.

[0011] The lithium battery pack charging device provided by the present invention may also have the following feature: wherein the single chip microcomputer is an Atmel89C51 single chip microcomputer.

[0012] The lithium battery pack charging device provided by the present invention may also have the following feature: wherein the voltage limit detection circuit includes two identical quad-comparators.

[0013] The lithium battery pack charging device provided by the present invention may also have the following feature: wherein the four comparators are LM339 type four comparators.

[0014] Functions and Effects of the Invention

[0015] According to the lithium battery pack charging device involved in the present invention, because it has a single-chip computer system, a controllable constant current source, a voltage limiting control circuit and a voltage limiting detection circuit, the single-chip computer reads the voltage value range of the current charged battery, and then converts it into a controllable constant current source circuit module for PWM output control voltage limiting control through a timer interrupt, and when the voltage is too high, the voltage limiting control circuit will automatically limit the maximum voltage and current. The third resistor in the voltage limiting control circuit needs to control the resistance value through the single-chip computer control relay to adjust the voltage limiting value, thereby adjusting and stabilizing the current of the charged battery. Therefore, the lithium battery pack charging device provided by the present invention can charge lithium batteries of different models, and has a simple structure, is easy to manufacture, and is low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of a lithium battery pack charging device in an embodiment of the present invention;

[0017] Figure 2 is a circuit diagram of a single chip computer system in an embodiment of the present invention;

[0018] Figure 3 is a circuit diagram of a controllable constant current source and a voltage limiting control circuit in an embodiment of the present invention; and

[0019] Figure 4 4 is a hardware pin diagram of the voltage limiting detection circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below in conjunction with embodiments and drawings.

[0021] <Example>

[0022] Figure 1 It is a schematic diagram of the structure of a lithium battery pack charging device in an embodiment of the present invention.

[0023] like Figure 1As shown, the lithium battery pack charging device provided in this embodiment includes: a single chip computer system 100 (ie, MCU), a controllable constant current source 200 , a voltage limiting control circuit 201 and a voltage limiting detection circuit 300 .

[0024] Figure 2 It is a circuit diagram of a single chip computer system in an embodiment of the present invention.

[0025] like Figure 2 As shown, the single-chip computer system 300 includes: a single-chip computer 108, a first resistor 107, a reset circuit and a crystal oscillator circuit.

[0026] In this embodiment, the single-chip microcomputer 108 adopts the MCU-Atmel89C51 type single-chip microcomputer, which is responsible for receiving the voltage range comparison signal transmitted by the voltage limiting detection circuit 300, and outputting a control signal to the voltage limiting control circuit 201, thereby setting the charging cut-off voltage for the controllable constant current source 200. The single-chip microcomputer system 100 is also responsible for setting the output current size of the controllable constant current source 200.

[0027] One end of the first resistor 107 is connected to the EA / VPP interface of the single chip computer 108, and the other end is connected to the power supply voltage. In this embodiment, the resistance value of the first resistor 107 is 4.7 kΩ.

[0028] The reset circuit includes: a first capacitor 101, a second capacitor 102 and a crystal oscillator 103. The first capacitor 101 and the second capacitor 102 are connected in series, the crystal oscillator 103 is connected in parallel with the first capacitor 101 and the second capacitor 102, the two ends of the crystal oscillator 103 are respectively connected to the XT1 interface and the XT2 interface of the single-chip computer 108, and a grounding interface is provided between the first capacitor 101 and the second capacitor 102.

[0029] The crystal oscillator circuit includes: an electrolytic capacitor 104, a tenth resistor 105 and a reset button 106. The positive electrode of the electrolytic capacitor 104 is connected to the reset button 106, and the negative electrode is respectively connected to the RST interface of the single-chip microcomputer 108 and the tenth resistor 105. One side of the reset button 106 is connected to the electrolytic capacitor 104, and the other side is connected to the tenth resistor 105 and the RST interface of the single-chip microcomputer 108. One end of the tenth resistor 105 is respectively connected to the reset button 106 and the negative electrode of the electrolytic capacitor 104, and the other end is grounded. A power supply voltage interface is provided between the electrolytic capacitor 104 and the reset button 106. In the present embodiment, the capacitance value of the electrolytic capacitor 104 is 10μF, and the resistance value of the tenth resistor 105 is 10kΩ.

[0030] Figure 3 It is a circuit diagram of a controllable constant current source and a voltage limiting control circuit in an embodiment of the present invention.

[0031] like Figure 3As shown, in this embodiment, the controllable constant current source 200 and the voltage limiting control circuit 201 are designed in the same circuit module, that is, the controllable constant current source circuit module of voltage limiting control. In other embodiments, the controllable constant current source 200 and the voltage limiting control circuit 201 can also be designed as two relatively independent circuit modules.

[0032] Specifically, the controllable constant current source circuit module of voltage limiting control includes a first transistor 205, a second transistor 206, a field effect transistor 207, a second resistor 202, a third resistor 203, a fourth resistor 204, a control port 208, a comparison detection port 209, a lithium battery pack positive electrode interface 210 and a lithium battery pack negative electrode interface 211.

[0033] The base electrode of the first transistor 205 is connected to the control port 208 through the fourth resistor 204, the base electrode is electrically connected to the gate of the field effect transistor 207, and the emitter electrode is connected to the lithium battery pack negative electrode interface 211. In this embodiment, the first transistor 205 is a PNP transistor.

[0034] The collector of the second transistor 206 is connected to the pre-stabilization voltage input terminal VIN through the second resistor 202, the base electrode is connected to the lithium battery pack positive electrode interface 210 through the third resistor 203, and the emitter electrode is connected to the lithium battery pack positive electrode interface 210. In this embodiment, the second transistor 206 is a PNP transistor.

[0035] The source of the field effect tube 207 is connected to the pre-stabilized voltage input terminal VIN, and the drain is connected to the positive electrode interface 210 of the lithium battery pack through the third resistor 203.

[0036] A ground terminal GND is provided on the connection line between the emitter electrode of the first transistor 205 and the negative electrode interface 211 of the lithium battery pack.

[0037] A comparison detection port 209 is provided on the connection line between the emitter electrode of the second triode 206 and the positive electrode interface 210 of the lithium battery pack.

[0038] The control port 208 is connected to the I / O port P3.4 (timing interrupt T0) of the single-chip microcomputer 108.

[0039] In this embodiment, the resistance values ​​of the second resistor 202 and the tenth resistor 204 are both 10 kΩ.

[0040] Figure 4 4 is a hardware pin diagram of the voltage limiting detection circuit in an embodiment of the present invention.

[0041] like Figure 4 As shown, the voltage limit detection circuit 300 is composed of two identical four comparators, which are used to compare with the set voltage interval threshold and output to the single chip computer system 100 for feedback through on-off output. In this embodiment, two LM339 four comparators are used.

[0042] Pins 5, 7, 9, and 11 of one of the LM339 quad comparators are connected to the corresponding voltage reference values ​​(3V, 4.2V, 6V, and 8.4V) obtained by power supply and resistor voltage division, pins 4, 6, 8, and 10 are connected to the comparison detection port 209 of the voltage limiting control circuit, and pins 1, 2, 3, and 4 are connected to the I / O ports P0.0 to P0.3 of the 89C51 single chip computer (108) respectively;

[0043] Pins 5 and 7 of another LM339 quad comparator are respectively connected to the corresponding voltage reference values ​​(9V, 12.6V) obtained by power supply and resistor voltage division, pins 4 and 6 are connected to the comparison detection port 209 of the controllable constant current source circuit module 200 of voltage limiting control, and pins 1 and 2 are respectively connected to the I / O ports P0.4 and P0.5 of the microcontroller 108.

[0044] The main operating principle of the lithium battery pack charging device provided in this embodiment is: the single-chip microcomputer 108 reads the current voltage value range of the charged battery through the I / O port P0.0~0.5 (read in through the voltage limiting detection circuit 300), and then converts it into a controllable constant current source circuit module 200 for PWM output control voltage limiting control through a timer interrupt, and when the voltage is too high, the voltage limiting control circuit 201 will automatically limit the maximum voltage and current, and the third resistor 203 in the voltage limiting control circuit 203 needs to control the relay through the single-chip microcomputer 108 to control the resistance value, adjust the voltage limiting value, and thus adjust and stabilize the current of the charged battery.

[0045] The method for using the lithium battery pack charging device provided in this embodiment is as follows: when charging, first use a trickle charge of 0.1C (C is the total capacity of the battery) for 30 minutes, and then use a current of 0.75-1C to charge for 15 minutes, and detect the current voltage value range from both ends of the battery through the voltage limit detection circuit 300 and return it to the single-chip computer system (100). If it is greater than 3V and less than 4.2V, the full charging voltage is 4.2V, if it is greater than 6V and less than 8.4V, the full charging voltage is 8.4V, if it is greater than 9V and less than 12.6V, the full charging voltage is 12.6V, and so on. When the voltage selection of any of the above items is met, the single-chip computer MCU100 determines the charging mode and the corresponding battery pack combination information, so as to charge according to the corresponding charging mode (give the corresponding control signal to the control port 208 of the controllable constant current source circuit module 200 of the voltage limit control). Then, the controllable constant current source circuit module 200 with voltage limiting control is used to charge at 0.75-1C in a pulsating manner for half an hour, and finally charged at 0.5C until the calibrated voltage value is reached. The single-chip microcomputer system 100 controls the current to gradually decrease, and finally reaches the calibrated voltage value, shuts off the circuit, and ends charging.

[0046] For example, to charge a battery pack consisting of two 18650 batteries (one with a capacity of 1500mAh) connected in series, charge at a current of 0.3A for 30 minutes, and then charge at a current of 2.5A for 15 minutes. At this time, the battery voltage has entered the corresponding voltage range (6V~8.4V). Start charging with a pulsating current of 2.5A for 30 minutes (to activate the battery and slow down the aging of the lithium battery), and finally charge with a current of 1.5A, and then gradually reduce it to zero before the end.

[0047] Functions and Effects of the Embodiments

[0048] According to the lithium battery pack charging device involved in this embodiment, because it has a single-chip microcomputer system, a controllable constant current source, a voltage limiting control circuit and a voltage limiting detection circuit, the single-chip microcomputer reads the voltage value range of the current charged battery, and then converts it into a PWM output control voltage limiting control control control control constant current source circuit module through a timer interrupt, and when the voltage is too high, the voltage limiting control circuit will automatically limit the maximum voltage and current. The third resistor in the voltage limiting control circuit needs to control the resistance value through the single-chip microcomputer control relay to adjust the voltage limiting value, thereby adjusting and stabilizing the current of the charged battery. Therefore, the lithium battery pack charging device provided in this embodiment can charge lithium batteries of different models, and has a simple structure, is easy to manufacture, and is low in cost.

[0049] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

Claims

1. A lithium battery pack charging device, used for charging lithium battery packs of various types, characterized in that: include: A controllable constant current source having at least one voltage detection point, electrically connected to a charging power source and the lithium battery pack respectively; A voltage limiting control circuit, electrically connected to the controllable constant current source through the voltage detection point; A single chip microcomputer system is electrically connected to the controllable constant current source and the voltage limiting control circuit respectively; as well as The voltage limiting monitoring circuit is electrically connected to the controllable constant current source and the single chip computer system respectively. The voltage limiting monitoring circuit is used to detect the voltage of the connection line between the controllable constant current source and the lithium battery pack and generate a voltage feedback signal to send to the single chip computer system. The single chip computer system sends an output voltage control signal to the voltage limiting control circuit and sends an output current control signal to the controllable constant current source according to the voltage feedback signal. The voltage limiting control circuit controls the maximum output voltage value of the controllable constant current source according to the output voltage control signal. The controllable constant current source controls the output current according to the output current control signal, The controllable constant current source and the voltage limiting control circuit form a controllable constant current source circuit module with voltage limiting control. The controllable constant current source circuit module of the voltage limiting control includes a first triode, a second triode, a field effect tube, a second resistor, a third resistor, a fourth resistor, a voltage input terminal before voltage stabilization, a control port, a comparison detection port, a positive electrode interface of a lithium battery pack, and a negative electrode interface of a lithium battery pack. The base electrode of the first triode is connected to the control port through the fourth resistor, the base electrode is electrically connected to the gate of the field effect tube, and the emitter electrode is connected to the negative electrode interface of the lithium battery pack. The collector of the second triode is connected to the pre-stabilized voltage input terminal through the second resistor, the base electrode is connected to the positive electrode interface of the lithium battery pack through the third resistor, and the emitter electrode is connected to the positive electrode interface of the lithium battery pack. The source of the field effect tube is connected to the pre-stabilization voltage input terminal, and the drain is connected to the positive electrode interface of the lithium battery pack through the third resistor. A ground terminal is provided on the connection line between the emitter electrode of the first triode and the negative electrode interface of the lithium battery pack. A comparison detection port is provided on the connection line between the emission electrode of the second triode and the positive electrode interface of the lithium battery pack. When charging, first use 0.1C trickle charge for 30 minutes, then use 0.75~1C current to charge for 15 minutes, and detect the current voltage value range from both ends of the battery through the voltage limit detection circuit and return it to the single-chip microcomputer system. The single-chip microcomputer determines the charging method and the corresponding battery pack combination information according to the current voltage value range of the charged battery, and converts it into a PWM output control voltage limit control control control constant current source circuit module through a timer interrupt. The controllable constant current source circuit module of the voltage limit control is charged at 0.75~1C for half an hour in a pulsating manner, and finally charged at 0.5C until the calibrated voltage value is reached. The single-chip microcomputer system controls the current to gradually decrease, and finally reaches the calibrated voltage value, shuts down the circuit, and the charging ends. When the voltage is too high, the voltage limiting control circuit automatically limits the maximum voltage and current. The third resistor controls the relay through the single chip microcomputer to control the resistance value, adjust the voltage limiting value, and thus adjust and stabilize the current of the charged battery.

2. The lithium battery pack charging device according to claim 1, characterized in that: in, The first transistor and the second transistor are both PNP transistors.

3. The lithium battery pack charging device according to claim 1, Features: Wherein, the single chip microcomputer system comprises: Single chip microcomputer; A first resistor, one end of which is connected to the EA / VPP interface of the single chip microcomputer, and the other end of which is connected to the power supply voltage; A reset circuit is connected to the XT1 interface and the XT2 interface of the single chip microcomputer respectively; and The crystal oscillator circuit is connected to the RST interface of the single chip microcomputer.

4. The lithium battery pack charging device according to claim 3, characterized in that: in, The reset circuit includes: a first capacitor, a second capacitor and a crystal oscillator. The first capacitor is connected in series with the second capacitor, the crystal oscillator is connected in parallel with the first capacitor and the second capacitor, two ends of the crystal oscillator are respectively connected to the XT1 interface and the XT2 interface of the single-chip computer, and a grounding interface is provided between the first capacitor and the second capacitor.

5. The lithium battery pack charging device according to claim 3, characterized in that: in, The crystal oscillator circuit includes: an electrolytic capacitor, a tenth resistor and a reset button. The positive electrode of the electrolytic capacitor is connected to the reset button, and the negative electrode is connected to the RST interface of the single-chip microcomputer and the tenth resistor respectively. One side of the reset button is connected to the electrolytic capacitor, and the other side is connected to the tenth resistor and the RST interface of the single chip microcomputer. One end of the tenth resistor is connected to the reset button and the negative electrode of the electrolytic capacitor respectively, and the other end is grounded. A power supply voltage interface is provided between the electrolytic capacitor and the reset button.

6. The lithium battery pack charging device according to claim 1, characterized in that: in, The single chip microcomputer is an Atmel89C51 single chip microcomputer.

7. The lithium battery pack charging device according to claim 1, characterized in that: in, The voltage limit detection circuit includes two identical quad comparators.

8. The lithium battery pack charging device according to claim 7, characterized in that: in, The four comparators are LM339 type four comparators.

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