CN115549280A - Direct current power supply switching circuit based on lithium battery charging and discharging - Google Patents
Direct current power supply switching circuit based on lithium battery charging and discharging Download PDFInfo
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- CN115549280A CN115549280A CN202211211072.1A CN202211211072A CN115549280A CN 115549280 A CN115549280 A CN 115549280A CN 202211211072 A CN202211211072 A CN 202211211072A CN 115549280 A CN115549280 A CN 115549280A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/061—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for DC powered loads
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
- H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
- H02J7/0049—Detection of fully charged condition
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
- H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention discloses a direct current power supply switching circuit based on lithium battery charging and discharging, which comprises: the device comprises a DC-DC buck-boost module, a battery charging management module, a lithium battery, a first diode and a second diode; the DC-DC voltage boosting and reducing module is used for regulating output voltage and is connected with the DC power adapter, the battery charging management module and the battery charging interface of the lithium battery; a battery power supply interface of the lithium battery is connected with the anode of the second diode; the cathode of the first diode is connected with the cathode of the second diode and the load; the battery charging management module is used for adjusting charging current and outputting a second preset voltage, wherein the second preset voltage is smaller than the first preset voltage. By adopting the embodiment of the invention, the power supply range is expanded by the DC-DC buck-boost module, and meanwhile, the automatic switching of the power supply source can be realized after the power failure of the DC power supply.
Description
Technical Field
The invention relates to the technical field of power supplies, in particular to a direct-current power supply switching circuit based on lithium battery charging and discharging.
Background
The existing rechargeable batteries mainly comprise lead-acid batteries, lithium batteries, nickel-hydrogen batteries and nickel-cadmium batteries. The charging process of the lithium battery is divided into the processes of pre-charging or trickle charging, constant-current charging, constant-voltage charging and the like. In general, in application, a lithium battery is charged first, and then a load is connected to the lithium battery to discharge after the lithium battery is disconnected from the charging. However, in some applications of short-time uninterruptible power supply devices, on one hand, a direct-current power supply is required to be used for supplying power to a load when direct-current power supply exists, and the direct-current power supply is automatically switched to lithium battery power supply when no direct-current power supply exists; on the other hand, when the direct current power supply exists, the lithium battery is charged by the direct current power supply, and when the direct current power supply does not exist, the lithium battery supplies power to the load. However, most lithium battery charging circuits do not support the input end and the output end to supply power, so that direct current power supply and simultaneous connection of lithium batteries to a load cannot be realized, and a dual-power supply function and a power supply mode automatic switching function cannot be realized; in addition, the charging management chips of these lithium battery charging circuits are basically voltage-dropping chips, so that the input voltage of the charging module needs to be higher than the charging voltage, and the practical use process has great limitations and inconvenience.
Disclosure of Invention
The invention provides a direct-current power supply switching circuit based on lithium battery charging and discharging, and aims to solve the technical problems that a multi-direct-current power supply circuit with a lithium battery is difficult to automatically switch power supply modes and the power supply range is limited.
In order to solve the above technical problem, an embodiment of the present invention provides a dc power switching circuit based on charging and discharging of a lithium battery, including: the device comprises a DC-DC buck-boost module, a battery charging management module, a lithium battery, a first diode and a second diode;
the input end of the DC-DC buck-boost module is connected with a DC power adapter;
the output end of the DC-DC buck-boost module is connected with the input end of the battery charging management module and the anode of the first diode;
the output end of the battery charging management module is connected with a battery charging interface of the lithium battery;
the battery power supply interface of the lithium battery is connected with the anode of the second diode;
the cathode of the first diode is connected with the cathode of the second diode and a load;
the DC-DC voltage boosting and reducing module is used for boosting or reducing the input voltage provided by the DC power adapter and outputting a first preset voltage;
the battery charging management module is used for adjusting the magnitude of constant current charging current and the magnitude of charging ending current; the second preset voltage is less than the first preset voltage;
the lithium battery is used for outputting a second preset voltage through the battery power supply interface; and the battery charging management module is used for charging according to the battery charging management module.
The DC-DC buck-boost module is connected with a load through a first diode, converts input voltage into first preset voltage, and expands the power supply range while supplying power to the load through the first diode; the battery charging management module converts the first preset voltage into a second preset voltage and charges the lithium battery, and the second preset voltage is smaller than the first preset voltage, so that the direct-current power supply preferentially supplies power to the load; and when the direct current power supply is in power failure, the lithium battery outputs a second preset voltage and supplies power to the load through the second diode, so that automatic switching is realized.
Further, the DC-DC buck-boost module includes: the circuit comprises a first chip, a first inductor, a third diode, a first resistor and a second resistor;
the input pin of the first chip is connected with the input end of the DC-DC buck-boost module, the enable pin of the first chip and the first inductor;
a switch pin of the first chip is connected with the second end of the first inductor and the anode of the third diode;
a feedback pin of the first chip is connected with a first end of the first resistor and a first end of the second resistor;
the second end of the first resistor is connected with the cathode of the third diode and the output end of the DC-DC buck-boost module;
and the second end of the second resistor is connected with the circuit ground.
The conversion of the input voltage is realized through the first chip, wherein the first inductor and the third diode are connected in series to form a divider resistor while filtering and rectifying are performed, the first resistor and the second resistor are connected in series, and the first chip adjusts the input voltage to be the first preset voltage through a feedback pin connected with the divider resistor, so that the power supply range is expanded, and the stability of the circuit is improved.
Further, the DC-DC buck-boost module further comprises: a first electrolytic capacitor and a first ceramic patch capacitor;
the positive electrode of the first electrolytic capacitor is connected with the input end of the DC-DC buck-boost module, the first end of the first ceramic patch capacitor, the input pin of the first chip, the enable pin of the first chip and the first end of the first inductor;
the negative electrode of the first electrolytic capacitor is connected with the circuit ground;
the second end of the first ceramic patch capacitor is connected to circuit ground.
The first electrolytic capacitor and the first ceramic patch capacitor are arranged at the input end, and play a role in filtering and storing energy of input voltage at high and low frequencies, so that the working stability of the circuit is improved.
Further, the DC-DC buck-boost module further comprises: a second electrolytic capacitor and a second ceramic patch capacitor;
the anode of the second electrolytic capacitor is connected with the first end of the second ceramic patch capacitor, the second end of the first resistor and the cathode of the third diode;
the negative electrode of the second electrolytic capacitor is connected with the circuit ground;
and the negative electrode of the second ceramic patch capacitor is connected with the circuit ground.
The second electrolytic capacitor and the second ceramic patch capacitor are arranged at the input end, and play a role in filtering and storing energy of input voltage at high and low frequencies, so that the working stability of the circuit is improved.
Further, the battery charging management module includes: the second chip, the PMOS tube, the fourth diode, the fifth diode, the second inductor, the first adjustable resistor and the second adjustable resistor;
the driving pin of the second chip is connected with the grid electrode of the PMOS tube;
the drain electrode of the PMOS tube is connected with the anode of the fourth diode;
the source electrode of the PMOS tube is connected with the input end of the battery charging management module;
the negative electrode of the fourth diode is connected with the negative electrode of the fifth diode and the first end of the second inductor;
the anode of the fifth diode is connected with the circuit ground;
a second end of the second inductor is connected to a charging current detection positive input pin of the second chip and a first end of the first adjustable resistor;
the second end of the first adjustable resistor is connected with the output end of the battery charging management module and the charging current detection negative input pin of the second chip;
the first end of the second adjustable resistor is connected with a finishing current setting pin of the second chip;
and the second end of the second adjustable resistor is connected with the circuit ground.
According to the invention, charging current is output through the connection of the second chip, the PMOS tube, the fourth diode, the fifth diode and the first inductor L1; the first adjustable resistor can adjust the output constant current charging current, and the second adjustable resistor is connected with the end current setting pin of the second chip to adjust the charging end current so as to meet the charging requirement of the lithium battery.
Further, the battery charging management module further includes: the LED lamp comprises a third resistor, a fourth resistor, a first LED lamp and a second LED lamp;
the first end of the third resistor is connected with the input end of the battery charging management module, the first end of the fourth resistor and the source electrode of the PMOS tube;
the second end of the third resistor is connected with the anode of the first LED lamp;
the negative electrode of the first LED lamp and the first drain electrode of the second chip are in open circuit and output pins are arranged;
a second end of the fourth resistor is connected with the anode of the second LED lamp;
and the negative electrode of the second LED lamp and the second drain electrode of the second chip are in open circuit and output pins.
According to the invention, the first LED lamp and the second LED lamp are respectively limited by the third resistor and the fourth resistor and are connected with the open-drain output pin of the second chip, so that the charging state can be indicated.
Further, the battery charging management module further includes: a third electrolytic capacitor and a third ceramic patch capacitor;
the anode of the third electrolytic capacitor is connected with the third ceramic chip capacitor, the input end of the battery charging management module and the grid electrode of the PMOS tube;
the negative electrode of the third electrolytic capacitor is connected with the circuit ground;
and the negative electrode of the third ceramic patch capacitor is connected with the circuit ground.
The third electrolytic capacitor and the third ceramic patch capacitor are arranged at the input end, and play a role in filtering and storing energy of input voltage at high and low frequencies, so that the working stability of the circuit is improved.
Further, the battery charging management module further includes: a fourth electrolytic capacitor and a fourth ceramic patch capacitor;
the positive electrode of the fourth electrolytic capacitor is connected with the fourth ceramic chip capacitor, the output end of the battery charging management module and the second end of the first adjustable resistor;
the negative electrode of the fourth electrolytic capacitor is connected with the circuit ground;
and the negative electrode of the fourth ceramic patch capacitor is connected with the circuit ground.
The fourth electrolytic capacitor and the fourth ceramic patch capacitor are arranged at the input end, and play a role in filtering and storing energy of input voltage at high and low frequencies, so that the working stability of the circuit is improved.
Further, the first adjustable resistor is used for adjusting the magnitude of the constant current charging current so as to adjust the constant current charging current to a first preset current; wherein the first preset current is:
wherein RP01 is the resistance of the first adjustable resistor.
The first adjustable resistor adjusts the constant current charging current, and meets the charging requirement of the lithium battery while realizing free switching of the circuit and expanding the power supply range.
Further, the second adjustable resistor is used for adjusting the magnitude of the charging end current so as to adjust the charging end current to a second preset current; wherein the second preset current is:
I EOC ＝(0.0916965+6.39*RP02)*I CH ；
wherein RP02 is the resistance of the second adjustable resistor, I CH A constant current charging current.
The second adjustable resistor adjusts the charging end current, and meets the charging requirement of the lithium battery while freely switching the circuit and expanding the power supply range.
Drawings
Fig. 1 is a schematic connection diagram of an embodiment of a dc power switching circuit based on charging and discharging of a lithium battery according to the present invention;
fig. 2 is a schematic connection diagram of an embodiment of a DC-DC buck-boost module provided in the present invention;
FIG. 3 is a schematic diagram illustrating a connection relationship of the first chip U1 according to an embodiment of the present invention;
fig. 4 is a schematic connection diagram of a battery charging management module according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a lithium battery charging process provided by the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example one
Referring to fig. 1, a schematic connection relationship diagram of an embodiment of a dc power switching circuit based on charging and discharging of a lithium battery provided by the present invention includes: the DC-DC buck-boost module, the battery charging management module, the lithium battery, the first diode D22 and the second diode D32;
the input end of the DC-DC buck-boost module is connected with a DC power adapter;
the output end of the DC-DC voltage boosting and reducing module is connected with the input end of the battery charging management module and the positive electrode of the first diode D22;
the output end of the battery charging management module is connected with a battery charging interface of the lithium battery;
the battery power supply interface of the lithium battery is connected with the anode of the second diode D32;
the cathode of the first diode D22 is connected with the cathode of the second diode D32 and a load;
the DC-DC voltage boosting and reducing module is used for boosting or reducing the input voltage provided by the DC power adapter and outputting a first preset voltage;
the battery charging management module is used for adjusting the magnitude of constant current charging current and the magnitude of charging ending current; the power supply is used for outputting a second preset voltage, wherein the second preset voltage is smaller than the first preset voltage;
the lithium battery is used for outputting a second preset voltage through the battery power supply interface; and the battery charging management module is used for charging according to the battery charging management module.
In this embodiment, both the DC power supply and the lithium battery can supply power to the load, the DC power supply adjusts the input voltage to a first preset voltage, for example, 13.5V, the output voltage of the lithium battery is adjusted to a second preset voltage, for example, 12.6V, by the battery charging management module, and the second preset voltage is smaller than the first preset voltage, so as to ensure that when both the DC power supplies can supply power to the load, the DC power supply is preferentially supplied by the first diode D22; when the direct current power supply is powered off or does not exist, the voltage of the cathode of the first diode D22 is always smaller than the voltage output by the second diode D32, so that the lithium battery is automatically switched to supply power for the load. In addition, the first and second diodes D22 and D32 may also prevent a reverse flow phenomenon when the power supply is switched.
In the present embodiment, the first diode D22 and the second diode D32 are schottky diodes, and the model may be SK54, and the voltage drop is 0.55V; when the first preset voltage is 13.5V, a voltage of 12.95V is applied to the load through the first diode D22; when the second preset voltage is 12.6V, a voltage of 12.05V is applied to the load through the second diode D32.
The lithium battery may be a three-lithium battery in this embodiment.
Referring to fig. 2, a schematic connection relationship diagram of an embodiment of a DC-DC buck-boost module provided in the present invention is shown, where the DC-DC buck-boost module includes: the circuit comprises a first chip U1, a first inductor L1, a third diode D1, a first resistor R1 and a second resistor R2;
an input pin of the first chip U1 is connected with an input end of the DC-DC buck-boost module, an enable pin of the first chip U1 and the first inductor L1;
a switch pin of the first chip U1 is connected to the second end of the first inductor L1 and the anode of the third diode D1;
a feedback pin of the first chip U1 is connected to a first end of the first resistor R1 and a first end of the second resistor R2;
the second end of the first resistor R1 is connected with the cathode of the third diode D1 and the output end of the DC-DC buck-boost module;
the second end of the second resistor R2 is connected to circuit ground.
In this embodiment, the inductance of the first inductor L1 may be 3.3uH-22uH, an inductor with a small dc resistance (DCR) may be selected to ensure high efficiency, and the third diode D1 may be a schottky diode, model SS54, and support a 5A high current capability. A feedback pin of the first chip U1 adjusts input voltage through a divider resistor formed by connecting the first resistor R1 and the second resistor R2, so that the second chip U2 outputs first preset voltage through a switch pin; wherein, the first preset voltage is:
Vout＝0.6*(1+R1/R2)；
wherein, R1 is the resistance of the first resistor R1, and R2 is the resistance of the second resistor R2.
Referring to fig. 3, a schematic diagram of a connection relationship of an embodiment of a first chip U1 according to the present invention is shown, wherein the first chip U1 can select an LN2220 chip to adjust an input voltage to output a first preset voltage, and the LN2220 is a miniature, high-efficiency, boost DC-DC regulator. The power supply supports the input of a 2-24V direct-current voltage range, can work efficiently and stably in a wider load range, and is internally provided with a 4A power switch and a soft start protection circuit. The conversion efficiency is up to 93%, and the output voltage can be set to 13.5V by adjusting two external resistors.
In this embodiment, the components for regulating the output voltage in LN2220 include: the device comprises an error amplifier, a pulse width regulator, a ramp compensation circuit and a power tube; when the input voltage or the load of the direct current power supply changes, the voltage at the switch pin of the DC-DC buck-boost module slowly changes, the change is detected by the feedback pin and is input to the inverting terminal of the error amplifier through the feedback pin, and then the voltage is compared with the reference voltage of the non-inverting terminal, such as 0.6V, and the error amplifier forms an output variable quantity; the output variable quantity is input to one end of the PWM regulator, and forms a recalibrated duty ratio with slope compensation, so that the power tube switch is controlled, and the circuit automatically regulates the output voltage to reach a first preset voltage.
According to the invention, the conversion of the input voltage is realized through the first chip U1, wherein the first inductor L1 and the third diode D1 are connected in series to form a divider resistor while filtering and rectifying, the first resistor R1 and the second resistor R2 are connected in series to form a divider resistor, and the first chip U1 adjusts the input voltage into a first preset voltage through a feedback pin connected with the divider resistor, so that the power supply range is expanded, and the stability of the circuit is improved.
Further, the DC-DC buck-boost module further comprises: a first electrolytic capacitor E2 and a first ceramic chip capacitor C2;
the positive electrode of the first electrolytic capacitor E2 is connected with the input end of the DC-DC buck-boost module, the first end of the first ceramic chip capacitor C2, the input pin of the first chip U1, the enable pin of the first chip U1 and the first end of the first inductor L1;
the negative electrode of the first electrolytic capacitor E2 is connected with the circuit ground;
and the second end of the first ceramic chip capacitor C2 is connected with the circuit ground.
Further, the DC-DC buck-boost module further comprises: a second electrolytic capacitor E1 and a second ceramic chip capacitor C1;
the anode of the second electrolytic capacitor E1 is connected with the first end of the second ceramic chip capacitor C1, the second end of the first resistor R1 and the cathode of the third diode D1;
the negative electrode of the second electrolytic capacitor E1 is connected with the circuit ground;
and the negative electrode of the second ceramic chip capacitor C1 is connected with the circuit ground.
In this embodiment, the electrolytic capacitor is used for low-frequency filtering and energy storage, and the ceramic chip capacitor is used for high-frequency filtering and energy storage; the requirements of instantaneous high load and low ripple inside the second chip U2 are met. The capacitance values of the first electrolytic capacitor E2 and the second electrolytic capacitor E1 can be selected from 47uf to 100uf, and the voltage resistance is 25V; the capacitance values of the first ceramic patch capacitor C2 and the second ceramic patch capacitor C1 can be selected to be 100nf, and 50V withstand voltage.
Referring to fig. 4, a schematic connection relationship diagram of an embodiment of a battery charging management module according to the present invention is shown, where the battery charging management module includes: the power supply circuit comprises a second chip U2, a PMOS (P-channel metal oxide semiconductor) tube M1, a fourth diode D4, a fifth diode D5, a second inductor L2, a first adjustable resistor RP1 and a second adjustable resistor RP2;
a driving pin of the second chip U2 is connected with a grid electrode of the PMOS tube M1;
the drain electrode of the PMOS tube M1 is connected with the anode of the fourth diode D4;
the source electrode of the PMOS tube M1 is connected with the input end of the battery charging management module;
the cathode of the fourth diode D4 is connected to the cathode of the fifth diode D5 and the first end of the second inductor L2;
the anode of the fifth diode D5 is connected to circuit ground;
a second end of the second inductor L2 is connected to a positive input pin of a charging current detection of the second chip U2 and a first end of the first adjustable resistor RP 1;
the second end of the first adjustable resistor RP1 is connected with the output end of the battery charging management module and the charging current detection negative input pin of the second chip U2;
the first end of the second adjustable resistor RP2 is connected with the ending current setting pin of the second chip U2;
and the second end of the second adjustable resistor RP2 is connected with the circuit ground.
In this embodiment, the model of the second chip U2 may be CN3703, the model of the PMOS transistor M1 may be AO4459 or AP4435GM, the model of the fourth diode D4 and the fifth diode D5 may be SSS54, the inductance of the second inductor L2 is 47uf to 100uf, and the second inductor L2 has a withstand voltage of 25V.
According to the invention, charging current is output through the connection of the second chip U2, the PMOS tube M1, the fourth diode D4, the fifth diode D5 and the first inductor L1; the first adjustable resistor RP1 can adjust the output constant-current charging current, and the second adjustable resistor RP2 is connected with the end current setting pin of the second chip U2 to adjust the charging end current so as to meet the charging requirement of the lithium battery.
Further, the battery charging management module further comprises: the LED lamp comprises a third resistor R4, a fourth resistor R5, a first LED lamp LED1 and a second LED lamp LED2;
the first end of the third resistor R4 is connected to the input end of the battery charging management module, the first end of the fourth resistor R5 and the source of the PMOS transistor M1;
the second end of the third resistor R4 is connected with the anode of the first LED lamp LED 1;
the negative electrode of the first LED lamp LED1 and a first drain electrode of the second chip U2 are in open circuit and output pins;
a second end of the fourth resistor R5 is connected to the anode of the second LED lamp LED2;
and the negative electrode of the second LED lamp LED2 and the second drain electrode of the second chip U2 are in open circuit and output pins.
In the present embodiment, when the first LED lamp LED1 is turned on and the second LED lamp LED2 is turned off, it indicates that the lithium battery is being charged; when the first LED lamp LED1 is turned off and the second LED lamp LED2 is turned on, the charging of the lithium battery is finished; when the first LED lamp LED1 and the second LED lamp LED2 both display a pulse signal, it indicates that the lithium battery is not connected.
According to the invention, the first LED lamp LED1 and the second LED lamp LED2 are respectively limited by the third resistor R4 and the fourth resistor R5 and are connected with the drain open-circuit output pin of the second chip U2, so that the charging state can be indicated.
Further, the battery charging management module further includes: a third electrolytic capacitor E4 and a third ceramic chip capacitor C5;
the positive electrode of the third electrolytic capacitor E4 is connected with the third ceramic chip capacitor C5, the input end of the battery charging management module and the grid electrode of the PMOS tube;
the negative electrode of the third electrolytic capacitor E4 is connected with the circuit ground;
and the negative electrode of the third ceramic chip capacitor C5 is connected with the circuit ground.
Further, the battery charging management module further includes: a fourth electrolytic capacitor E3 and a fourth ceramic chip capacitor C3;
the positive electrode of the fourth electrolytic capacitor E3 is connected with the fourth ceramic chip capacitor C3, the output end of the battery charging management module and the second end of the first adjustable resistor RP 1;
the negative electrode of the fourth electrolytic capacitor E3 is connected with the circuit ground;
and the negative electrode of the fourth ceramic chip capacitor C3 is connected with the circuit ground.
In the embodiment, the capacitance values of the third electrolytic capacitor E4 and the fourth electrolytic capacitor E3 can be selected from 47uf to 100uf, and the voltage resistance is 25V; the capacitance values of the third ceramic chip capacitor C5 and the fourth ceramic chip capacitor C3 can be selected to be 100nf, and the voltage resistance is 50V; the inductance of the second capacitor may be 8-47uH.
The first ceramic chip capacitor, the second ceramic chip capacitor, the third ceramic chip capacitor and the four-ceramic chip capacitor are arranged at the input end, so that the high-low frequency filtering and energy storage effects on input voltage are achieved, and the working stability of the circuit is improved.
In this embodiment, the battery temperature monitoring input pin of the second chip U2 is connected to a first end of a fifth resistor, and a second end of the fifth resistor is connected to circuit ground; wherein, the fifth resistor is a thermistor with a negative temperature coefficient.
In this embodiment, a capacitor with a capacitance value of 470pF is connected between the first loop compensation input pin of the second chip U2 and the circuit ground; a sixth resistor with a series resistance value of 120 Ω and a capacitor with a capacitance value of 220nF are connected to the second loop compensation input pin of the second chip U2; the third loop compensation input pin of the second chip U2 is connected to a capacitor with a capacitance value of 100nF to circuit ground.
Referring to fig. 5, which is a schematic diagram of a charging process of a lithium battery provided in the present invention, a battery charging management module is used to perform trickle charging first when charging a deep-discharge lithium battery or three lithium batteries; and when the charging voltage reaches a voltage threshold value, entering a constant current charging state.
Further, the first adjustable resistor RP1 is configured to adjust a magnitude of a constant current charging current, so that the constant current charging current is adjusted to a first preset current; wherein the first preset current is:
wherein RP01 is the resistance of the first adjustable resistor RP 1.
The first adjustable resistor RP1 of the invention adjusts the constant current charging current, and meets the charging requirement of the lithium battery while realizing free switching of the circuit and expanding the power supply range.
In this embodiment, after the charging state enters the constant voltage charging state from the constant current charging state, the current is gradually decreased to the charging end current, where the second adjustable resistor RP2 is used to adjust the magnitude of the charging end current, so that the charging end current is adjusted to the second preset current; wherein the second preset current is:
I EOC ＝(0.0916965+6.39*RP02)*I CH ；
wherein RP02 is the resistance of the second adjustable resistor RP2, I CH A constant current is charged.
In the embodiment, the charging current is adjustable from 0.1A to 5A through an adjustable resistor, so as to meet different charging current requirements; the control of the charging end current is realized through the potentiometer, the charging end current can be set to be 10% -70% of the constant-current charging current, and the function of controlling the full charge quantity is realized.
The DC-DC buck-boost module is connected with a load through a first diode D22, converts input voltage into first preset voltage, and expands the power supply range while supplying power to the load through the first diode D22; the battery charging management module converts the first preset voltage into a second preset voltage and charges the lithium battery, and the second preset voltage is smaller than the first preset voltage, so that the direct-current power supply preferentially supplies power to the load; and when the direct current power supply is powered off, the lithium battery outputs a second preset voltage and supplies power to the load through a second diode D32, so that automatic switching is realized.
The above-mentioned embodiments are provided to further explain the objects, technical solutions and advantages of the present invention in detail, and it should be understood that the above-mentioned embodiments are only examples of the present invention and are not intended to limit the scope of the present invention. It should be understood that any modifications, equivalents, improvements and the like, which come within the spirit and principle of the invention, may occur to those skilled in the art and are intended to be included within the scope of the invention.
Claims (10)
1. A direct current power supply switching circuit based on lithium battery charging and discharging is characterized by comprising: the device comprises a DC-DC buck-boost module, a battery charging management module, a lithium battery, a first diode and a second diode;
the input end of the DC-DC buck-boost module is connected with a DC power adapter;
the output end of the DC-DC buck-boost module is connected with the input end of the battery charging management module and the anode of the first diode;
the output end of the battery charging management module is connected with a battery charging interface of the lithium battery;
a battery power supply interface of the lithium battery is connected with the anode of the second diode;
the cathode of the first diode is connected with the cathode of the second diode and a load;
the DC-DC voltage boosting and reducing module is used for boosting or reducing the input voltage provided by the DC power adapter and outputting a first preset voltage;
the battery charging management module is used for adjusting the magnitude of constant current charging current and the magnitude of charging finishing current; the power supply is used for outputting a second preset voltage, wherein the second preset voltage is smaller than the first preset voltage;
the lithium battery is used for outputting a second preset voltage through the battery power supply interface; and the battery charging management module is used for charging according to the battery charging management module.
2. The lithium battery charging and discharging-based direct-current power supply switching circuit according to claim 1, wherein the DC-DC buck-boost module comprises: the circuit comprises a first chip, a first inductor, a third diode, a first resistor and a second resistor;
the input pin of the first chip is connected with the input end of the DC-DC buck-boost module, the enable pin of the first chip and the first inductor;
a switch pin of the first chip is connected with the second end of the first inductor and the anode of the third diode;
a feedback pin of the first chip is connected with a first end of the first resistor and a first end of the second resistor;
the second end of the first resistor is connected with the cathode of the third diode and the output end of the DC-DC buck-boost module;
the second end of the second resistor is connected with circuit ground.
3. The lithium battery charging and discharging-based direct-current power supply switching circuit according to claim 2, wherein the DC-DC buck-boost module further comprises: a first electrolytic capacitor and a first ceramic patch capacitor;
the positive electrode of the first electrolytic capacitor is connected with the input end of the DC-DC buck-boost module, the first end of the first ceramic patch capacitor, the input pin of the first chip, the enable pin of the first chip and the first end of the first inductor;
the negative electrode of the first electrolytic capacitor is connected with the circuit ground;
the second end of the first ceramic patch capacitor is connected with circuit ground.
4. The lithium battery charging and discharging-based direct current power supply switching circuit according to claim 2, wherein the DC-DC buck-boost module further comprises: a second electrolytic capacitor and a second ceramic patch capacitor;
the anode of the second electrolytic capacitor is connected with the first end of the second ceramic patch capacitor, the second end of the first resistor and the cathode of the third diode;
the negative electrode of the second electrolytic capacitor is connected with the circuit ground;
and the negative electrode of the second ceramic patch capacitor is connected with the circuit ground.
5. The lithium battery charging and discharging-based direct current power supply switching circuit according to claim 1, wherein the battery charging management module comprises: the second chip, the PMOS tube, the fourth diode, the fifth diode, the second inductor, the first adjustable resistor and the second adjustable resistor;
the driving pin of the second chip is connected with the grid electrode of the PMOS tube;
the drain electrode of the PMOS tube is connected with the anode of the fourth diode;
the source electrode of the PMOS tube is connected with the input end of the battery charging management module;
the cathode of the fourth diode is connected with the cathode of the fifth diode and the first end of the second inductor;
the anode of the fifth diode is connected with circuit ground;
a second end of the second inductor is connected with a charging current detection positive input pin of the second chip and a first end of the first adjustable resistor;
the second end of the first adjustable resistor is connected with the output end of the battery charging management module and the charging current detection negative input pin of the second chip;
the first end of the second adjustable resistor is connected with a finishing current setting pin of the second chip;
and the second end of the second adjustable resistor is connected with the circuit ground.
6. The lithium battery charging and discharging-based direct-current power supply switching circuit according to claim 5, wherein the battery charging management module further comprises: the LED lamp comprises a third resistor, a fourth resistor, a first LED lamp and a second LED lamp;
the first end of the third resistor is connected with the input end of the battery charging management module, the first end of the fourth resistor and the source electrode of the PMOS tube;
the second end of the third resistor is connected with the anode of the first LED lamp;
the negative electrode of the first LED lamp and the first drain electrode of the second chip are in open circuit and output pins are arranged;
a second end of the fourth resistor is connected with the anode of the second LED lamp;
and the cathode of the second LED lamp and the second drain electrode of the second chip are in open circuit and output pins.
7. The lithium battery charging and discharging-based direct-current power supply switching circuit according to claim 5, wherein the battery charging management module further comprises: a third electrolytic capacitor and a third ceramic patch capacitor;
the positive electrode of the third electrolytic capacitor is connected with the third ceramic chip capacitor, the input end of the battery charging management module and the grid electrode of the PMOS tube;
the negative electrode of the third electrolytic capacitor is connected with the circuit ground;
and the negative electrode of the third ceramic patch capacitor is connected with the circuit ground.
8. The lithium battery charging and discharging-based direct current power supply switching circuit according to claim 5, wherein the battery charging management module further comprises: a fourth electrolytic capacitor and a fourth ceramic patch capacitor;
the positive electrode of the fourth electrolytic capacitor is connected with the fourth ceramic chip capacitor, the output end of the battery charging management module and the second end of the first adjustable resistor;
the negative electrode of the fourth electrolytic capacitor is connected with the circuit ground;
and the negative electrode of the fourth ceramic patch capacitor is connected with the circuit ground.
9. The lithium battery charging and discharging-based direct current power supply switching circuit according to any one of claims 5-8, wherein the first adjustable resistor is used for adjusting the magnitude of a constant current charging current so that the constant current charging current is adjusted to a first preset current; wherein the first preset current is:
wherein RP01 is the resistance of the first adjustable resistor.
10. The lithium battery charging and discharging-based direct current power supply switching circuit according to any one of claims 5-8, wherein the second adjustable resistor is used for adjusting the magnitude of the charging end current so as to adjust the charging end current to a second preset current; wherein the second preset current is:
I EOC ＝(0.0916965+6.39*RP02)*I CH ；
wherein RP02 is the resistance of the second adjustable resistor, I CH A constant current charging current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211211072.1A CN115549280A (en) | 2022-09-30 | 2022-09-30 | Direct current power supply switching circuit based on lithium battery charging and discharging |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211211072.1A CN115549280A (en) | 2022-09-30 | 2022-09-30 | Direct current power supply switching circuit based on lithium battery charging and discharging |
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| CN115549280A true CN115549280A (en) | 2022-12-30 |
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| CN202211211072.1A Pending CN115549280A (en) | 2022-09-30 | 2022-09-30 | Direct current power supply switching circuit based on lithium battery charging and discharging |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116404738A (en) * | 2023-02-21 | 2023-07-07 | 南京汉科明德医疗科技有限公司 | UPS module based on high-voltage battery pack |
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2022
- 2022-09-30 CN CN202211211072.1A patent/CN115549280A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116404738A (en) * | 2023-02-21 | 2023-07-07 | 南京汉科明德医疗科技有限公司 | UPS module based on high-voltage battery pack |
| CN116404738B (en) * | 2023-02-21 | 2024-05-17 | 南京汉科明德医疗科技有限公司 | UPS module based on high-voltage battery pack |
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