CN202817843U - Lithium battery charging circuit which can be charged while using and is used on laser surveying and mapping instrument - Google Patents

Abstract

The utility model discloses a lithium battery charging circuit which can be charged while using, wherein the lithium battery charging circuit can be placed in the battery box of a laser surveying and mapping instrument. The lithium battery charging circuit comprises an external power interface (1), a lithium battery charging management unit(2), a 8.4V lithium ion battery pack (3), a power switching circuit (4) and a surveying and mapping instrument interface (5). The lithium battery charging circuit has the following advantages: the lithium battery charging circuit can be charged while using, so the advantage of flexible and convenient utilization can be realized, and the lithium battery charging circuit is suitable for various occasions; compared with a dry battery, a nickel-hydrogen rechargeable battery and a nickel-cadmium rechargeable battery, for a lithium ion battery pack, importantly, under the condition of a same battery power, the size of the lithium ion battery pack is much smaller than the size of the dry battery, the size of the nickel-hydrogen rechargeable battery and the size of the nickel-cadmium rechargeable battery; the internal resistance of the lithium ion rechargeable battery is much smaller than the internal resistance of the nickel-hydrogen rechargeable battery and the internal resistance of the nickel-cadmium rechargeable battery, so the loss of the battery itself can be effectively reduced, and the energy conversion and utilization efficiency can be improved; compared with the nickel-hydrogen rechargeable battery and the nickel-cadmium rechargeable battery, the memory effect of the lithium ion battery is small or can be ignored completely; and the time of the surveying and mapping operation of the surveying and mapping instrument can be prolonged, and the working efficiency of the operation of the surveying and mapping instrument can be improved.

Description

A lithium battery charging circuit that can be used while charging for laser surveying and mapping instruments

technical field

The utility model relates to the technical field of laser surveying and mapping instruments, in particular to a lithium battery charging circuit used for laser surveying and mapping instruments which can be used while charging.

Background technique

Some existing surveying and mapping instruments are powered by nickel-metal hydride and nickel-cadmium rechargeable batteries, and some are powered by alkaline dry batteries. However, traditional nickel-hydrogen and nickel-cadmium rechargeable batteries have small capacity, large volume, and memory effect. Alkaline dry batteries have a smaller capacity and are consumables that need to be replaced for a long time. The replaced batteries cause serious pollution to the environment. Nowadays, surveying and mapping instruments are widely used in interior decoration, outdoor road construction, engineering installation, building construction, engineering supervision, etc., and even in special environments such as uninhabited remote mountainous areas. The complex and changeable application environment puts forward higher requirements for the power supply system of surveying and mapping instruments.

Contents of the invention

The purpose of this utility model is to overcome the many inconveniences of the power supply of the above-mentioned surveying and mapping instruments in practical applications, to provide an easy-to-use lithium battery charging circuit scheme that can be used while charging on the surveying and mapping instruments, and completely solve the problem of surveying and mapping instruments. In the complex and changeable application environment, the power supply of the instrument has a short service life and needs to be replaced or charged frequently. The indoor operation of the surveying and mapping instrument cannot use the external 220V AC mains, and the outdoor operation cannot use the external high-capacity battery. work efficiency. The utility model applies the power supply solutions of notebooks, mobile phones and other electronic products to surveying and mapping instruments, and uses the current high reliability, large capacity, and pollution-free lithium-ion battery packs for power supply, which can facilitate external connection of various power supplies, such as high-capacity Lead-acid storage battery, 220V AC mains power, etc. In addition, because the lithium battery has no memory effect, this utility model can also charge the instrument during the use of the instrument, prolonging the surveying and mapping operation time of the surveying and mapping instrument. It completely solves the problem that the surveying and mapping instrument supplies power to the instrument in various application occasions.

The technical scheme of the utility model is as follows:

A lithium battery charging circuit that can be used while charging includes: an external power supply interface 1, a lithium battery charging management unit 2, an 8.4V lithium ion battery pack 3, a power switching circuit 4, and a surveying and mapping instrument interface 5; the external power supply Interface 1 is connected to interface J1; the positive terminal interface of 8.4V lithium-ion battery pack 3 is connected to interface J3, the negative terminal interface of lithium-ion rechargeable battery pack is connected to interface J4, and the thermistor interface of lithium-ion rechargeable battery pack is connected to the interface J5 is connected; the positive power supply interface of surveying and mapping instrument interface 5 is connected with interface J2; the negative power supply interface of surveying and mapping instrument interface 5 is connected with interface J6.

The lithium battery charging management unit 2 includes: lithium ion battery pack charging management chip U1, power filter capacitors C1, C2, C3, C6, bootstrap capacitor C4, stop charging time programming capacitor C5, voltage loop compensation capacitor C7, Current loop compensation capacitor C8, anti-reverse power Schottky diode D1, common cathode double Schottky diode D3, rectifier diode D4, common anode two-color LED D5, LED current limiting resistors R3, R4, charging current setting resistor R5, temperature sampling voltage divider resistor R6, voltage loop compensation resistor R7, current loop compensation resistor R8, negative temperature coefficient thermistor RNTC, filter inductor L1, external power input connector J1, positive terminal interface of lithium-ion rechargeable battery pack J3, lithium ion rechargeable battery pack negative terminal interface J4, lithium ion rechargeable battery pack thermistor interface J5, instrument power supply negative terminal interface J6. in:

a. The first pin of the lithium-ion battery pack charging management chip U1 is connected to one end of the resistor R6, one end of the thermistor RNTC and the interface J5, the second pin is connected to one end of the resistor R3, and the third pin is connected to one end of the resistor R4 The 4th pin is connected to one end of the capacitor C3, the 6th pin is connected to the other end of the capacitor C3 and grounded, the 7th pin is connected to the 4th pin, the other end of the resistor R6 and the 2nd pin of the two-color light-emitting diode D5 , the 8th pin is connected to one end of resistor R7, the 9th pin is connected to one end of resistor R8, the 10th pin is connected to one end of resistor R5, one end of capacitor C6 and the interface J3, the 11th pin is connected to one end of inductor L1 and the other end of resistor R5 One end is connected, the 12th pin is connected to one end of capacitor C5 and grounded, the 13th pin is connected to the other end of capacitor C5, the 14th pin is connected to one end of capacitor C4, the 15th pin is connected to the other end of capacitor C4 and diode D3 The first pin and the third pin are connected, and the 16th pin is connected with one end of the capacitor C2 and the cathode of the diode D1.

b. The anode of the anti-power supply reverse connection Schottky diode D1 is connected to one end of the capacitor C1 and the first pin of the external power input connector J1; the other end of the capacitor C1 is connected to the second pin of the connector J1 and grounded; the other end of the resistor R3 is connected to the third pin of the two-color light-emitting diode D5; the other end of the resistor R4 is connected to the first pin of the two-color light-emitting diode D5; the other end of the resistor R7 is connected to one end of the capacitor C7; The other end of C7 is grounded; the other end of resistor R8 is connected to one end of capacitor C8; the other end of capacitor C8 is connected to interface J6 and grounded; the other end of inductor L1 is connected to the second leg of diode D3 and the cathode of rectifier diode D4 ; The cathode of the rectifier diode D4 is grounded; the other end of the capacitor C6 is connected to the interface J4; the other end of the capacitor C2 is grounded.

The power switching circuit 4 includes: anti-current backflow protection Schottky diode D2, voltage divider resistors R1, R2, P-MOS field effect transistor Q1, and instrument power supply positive terminal interface J2. The anode of the diode D2 is connected with one end of the resistor R1 and the first pin of the external power input connector J1; the cathode of the diode D2 is connected with the D end of the P-MOS field effect transistor Q1 and the positive interface J2 of the instrument power supply ; The S terminal of the P-MOS field effect transistor Q1 is connected to the positive terminal interface J3 of the lithium-ion rechargeable battery pack; the G terminal of the P-MOS field effect transistor Q1 is connected to the other end of the resistor R1 and one end of the resistor R2; The other end is grounded.

Wherein the external power supply 1 can be a 220V AC to 12V DC power adapter, or a 12V large-capacity lead-acid storage battery, etc., and its function is to provide energy for charging the lithium-ion battery; the lithium battery charging management unit 2 consists of an integrated It mainly completes the charging management of lithium-ion batteries, including charging current programming, charging status indication, battery temperature monitoring, charging current limiting, charging thermal switch management and programmable Stop charging time setting, etc.; 8.4V lithium-ion battery pack 3 is composed of two 3.7V/2200mAh 18650 batteries connected in series, and then connected in parallel with another group of 3.7V/2200mAh 18650 batteries. 8.4V/4400mAh high-power lithium-ion battery pack, which also includes a short-circuit protection circuit unit and an over-discharge protection circuit unit to prolong the service life of the lithium-ion battery pack; the power switching circuit 4 is composed of a low on-resistance P-MOS The field effect tube switch circuit is used to disconnect the original lithium battery to discharge the surveying and mapping instrument when using an external power supply to charge the lithium battery, and switch to the external power supply to supply power to the surveying and mapping instrument, so as to realize charging the lithium-ion battery pack while simultaneously charging the lithium-ion battery pack. The power supply function of the surveying and mapping instrument; the surveying and mapping instrument 5 contains a voltage regulation management chip, so that the surveying and mapping instrument can adapt to the power supply of 8.4V lithium-ion battery pack and 12V external DC power supply at the same time.

The basic working principle of the utility model: to supply power to the instrument power supply, the remaining power of lithium ions can be used to supply power to the instrument, and an external power supply can also be used to supply power to the instrument. When there is no external power supply at the J1 port, the G terminal of the P-MOS transistor Q1 is at a low level, Vgs is at a low level, the field effect transistor Q1 is turned on, and the output of the J2 interface is the lithium battery voltage. The P-MOS field effect transistor with very small conduction resistance Rgd is selected here, which reduces the power loss on the switch tube. When the J1 port is plugged into an external power supply, the voltage of the G terminal is about 12V, the voltage of the S terminal is the lithium battery output, the maximum output is 8.4V, Vgs is high, the field effect transistor Q1 is cut off, and the external power supply voltage passes through the diode D2 to the J2 port , at this time, the power supply of the instrument is the power of the external power supply. While plugging in the external power supply, the lithium battery charging management chip starts to charge the lithium battery pack. Since the lithium battery has no memory effect, it can be charged in time, and its charging times are limited, but note that the life of the charging times refers to the number of times of full charging and discharging. In other words, it has a life of 500 times of full charging. Just charge half of it, and it has a charging life of 1000 times. This charging method has been widely used in portable electronic products, such as mobile phones and notebook computers. This design is used in the process of charging the lithium battery, disconnecting the lithium battery for external discharge, avoiding the problem of redischarging the lithium battery pack during charging, and effectively prolonging the service life of the lithium battery pack.

In summary, the utility model has the following advantages: (1), it can be used while charging, flexible and convenient to use, and can be adapted to various occasions: a lithium battery charging circuit of the utility model that can be used while charging can be used indoors , Portable and mobile use anywhere outdoors; indoors can be connected to 220V AC mains for long-term convenient use, saving the trouble of frequent battery replacement; in special outdoor environments, it can also be equipped with large-capacity lead-acid batteries to extend the use time, saving The hassle of not being able to charge the battery. (2) Small size and high capacity: Compared with dry batteries, nickel-metal hydride and nickel-cadmium rechargeable batteries, and lithium-ion battery packs, the important thing is that under the same power condition, the volume of lithium-ion battery packs is larger than that of dry batteries and nickel-metal hydride and nickel-cadmium rechargeable batteries. The volume is much smaller. This advantage is particularly prominent, and it reflects the significant advantages of this portable product that is easy to carry and can be used for a longer period of time. (3) High efficiency: The internal resistance of lithium-ion rechargeable batteries is much smaller than that of nickel-metal hydride and nickel-cadmium rechargeable batteries, which can effectively reduce the loss of the battery itself. The efficiency of energy conversion and use is improved. (4) No memory effect: Compared with nickel-metal hydride and nickel-cadmium rechargeable batteries, the memory effect of lithium-ion batteries is smaller, which can be completely ignored. If the battery is a nickel-cadmium battery that is not fully charged and discharged for a long time, it is easy to leave traces in the battery due to the battery memory effect and reduce the battery capacity. Lithium-ion batteries do not have this effect. (5) The surveying and mapping operation time of the surveying and mapping instrument is extended, and the working efficiency of the surveying and mapping instrument is improved.

Description of drawings

Fig. 1 is a functional block diagram of the utility model for realizing charging while using.

Fig. 2 is a schematic diagram of the circuit for charging while using the utility model.

Detailed ways

As shown in Figure 1, a lithium battery charging circuit that can be used while charging, including an external power supply interface 1, a lithium battery charging management unit 2, an 8.4V lithium ion battery pack 3, a power switching circuit 4, and an interface for surveying and mapping instruments 5. The external power supply interface 1 is connected to the interface J1; the positive terminal interface of the 8.4V lithium-ion battery pack 3 is connected to the interface J3, the negative terminal interface of the lithium-ion rechargeable battery pack is connected to the interface J4, and the lithium-ion rechargeable battery pack The group thermistor interface is connected to interface J5; the positive power supply interface of surveying and mapping instrument interface 5 is connected to interface J2; the negative power supply interface of surveying and mapping instrument interface 5 is connected to interface J6.

As shown in Figure 2, the working process of a lithium battery charging circuit that can be used while charging is: U1 is used as the MP2610ER as the charging management chip of the lithium-ion battery pack. The diode D1 powers up the chip U1, and the chip first precharges the lithium battery pack, and the precharge adopts PWM mode to output a pulsating 8.4V level. When the voltage of the lithium battery rises after the pre-charging process, the chip enters the constant voltage charging mode, and the charging process is indicated by the two-color light-emitting diode D5. When the color of the light-emitting diode is orange, it means that it is charging; when the color of the light-emitting diode is green, it means Charging is completed; when the light-emitting diode is off, it means that the external power supply is under-voltage locked, or the thermal shutdown stops working, or the charging is stopped after the set time is exceeded, or the charging is disabled. The charging current can be determined by the resistor R5, the specific calculation method is 200mV/R5, and the maximum charging current should not exceed 2A. When the battery is almost full, it enters the trickle charging process. The trickle charging time and stop charging time are set by capacitor C5. Hour xC5)/0.1uF. During the charging process, the chip monitors the battery temperature through the negative temperature coefficient thermistor. When the charging environment temperature is too high, the chip will stop charging the battery.

When there is no external power supply at the J1 port, the G terminal of the P-MOS transistor Q1 is at a low level, Vgs is at a low level, the field effect transistor Q1 is turned on, and the output of the J2 interface is the lithium battery voltage. The P-MOS field effect transistor with very small conduction resistance Rgd is selected here, which reduces the power loss on the switch tube. When the J1 port is plugged into an external power supply, the voltage of the G terminal is about 12V, the voltage of the S terminal is the lithium battery output, the maximum output is 8.4V, Vgs is high, the field effect transistor Q1 is cut off, and the external power supply voltage passes through the diode D2 to the J2 port , at this time, the power supply of the instrument is the power of the external power supply. While plugging in the external power supply, the lithium battery charge management chip U1 starts to charge the lithium battery pack.

Claims (3)

1. but a lithium battery charging circuit of using while filling can be positioned in the laser mapping instrument battery case, and it comprises: external power interface (1), lithium cell charging administrative unit (2), 8.4V lithium ion battery group (3), power supply switch circuit (4), instrument of surveying and mapping instrumentation tap (5); Described external power interface (1) is connected with interface J1; 8.4V the positive end interface of lithium ion battery group (3) is connected with interface J3, Li-Ion rechargeable battery group negative terminal interface is connected with interface J4, and Li-Ion rechargeable battery group thermistor interface is connected with interface J5; The positive end interface of power supply of instrument of surveying and mapping instrumentation tap (5) is connected with interface J2; The power supply negative terminal interface of instrument of surveying and mapping instrument interface (5) is connected with interface J6.

2. but root a tree name a kind of lithium battery charging circuit of using while filling claimed in claim 1, it is characterized in that: described lithium cell charging administrative unit (2) comprising: lithium ion battery group charging management chip U1, power filtering capacitor C1, C2, C3, C6, bootstrap capacitor C4, stop charging interval programming capacitor C 5, voltage loop building-out capacitor C7, current loop building-out capacitor C8, anti-power supply reversal connection Schottky diode D1, the two Schottky diode D3 of common cathode, rectifier diode D4, common anode utmost point dichromatic LED D5, luminous tube current-limiting resistance R3, R4, charging current arranges resistance R 5, temperature sampling divider resistance R6, voltage loop compensating resistance R7, current loop compensating resistance R8, negative tempperature coefficient thermistor RNTC, filter inductance L1, external power source input connector J1, the positive end interface J3 of Li-Ion rechargeable battery group, Li-Ion rechargeable battery group negative terminal interface J4, Li-Ion rechargeable battery group thermistor interface J5, instrument power supply negative terminal interface J6, wherein:

A. the 1st pin of described lithium ion battery group charging management chip U1 and resistance R 6 one ends, thermistor RNTC one end and interface J5 are connected, the 2nd pin is connected with resistance R 3 one ends, the 3rd pin is connected with resistance R 4 one ends, the 4th pin is connected with capacitor C 3 one ends, the 6th pin is connected with capacitor C 3 other ends and ground connection, the 7th pin and the 4th pin, the 2nd pin of the other end of resistance R 6 and dichromatic LED D5 is connected, the 8th pin is connected with resistance R 7 one ends, the 9th pin is connected with resistance R 8 one ends, the 10th pin and resistance R 5 one ends, capacitor C 6 one ends and interface J3 are connected, the 11st pin is connected with the other end of inductance L 1 one ends and resistance R 5, the 12nd pin is connected with capacitor C 5 one ends and ground connection, the 13rd pin is connected with the other end of capacitor C 5, the 14th pin is connected with capacitor C 4 one ends, the 1st pin of the other end of the 15th pin and capacitor C 4 and diode D3, the 3rd pin is connected, and the 16th pin is connected with an end of capacitor C 2 and the negative pole of diode D1;

B. the positive pole of described anti-power supply reversal connection Schottky diode D1 is connected with an end of capacitor C 1 and the 1st pin of external power source input connector J1; The other end of capacitor C 1 is connected with the 2nd pin of connector J1 and ground connection; The other end of resistance R 3 is connected with the 3rd pin of dichromatic LED D5; The other end of resistance R 4 is connected with the 1st pin of dichromatic LED D5; The other end of resistance R 7 is connected with capacitor C 7 one ends; The other end ground connection of capacitor C 7; The other end of resistance R 8 is connected with capacitor C 8 one ends; The other end of capacitor C 8 is connected with interface J6 and ground connection; The other end of inductance L 1 is connected with the 2nd pin and the rectifier diode D4 negative pole of diode D3; Rectifier diode D4 minus earth; The other end of capacitor C 6 is connected with interface J4; The other end ground connection of capacitor C 2.

3. but root a tree name a kind of lithium battery charging circuit of using while filling claimed in claim 1, it is characterized in that: described power supply switch circuit (4) comprising: anti-electric current pours in down a chimney protection Schottky diode D2, divider resistance R1, R2, P-MOS field effect transistor Q1, the positive end interface J2 of instrument power supply; Wherein said diode D2 is anodal to be connected with an end of resistance R 1 and the 1st pin of external power source input connector J1; Diode D2 negative pole is connected with D end and the positive end interface J2 of instrument power supply of P-MOS field effect transistor Q1; The S end of P-MOS field effect transistor Q1 is connected with the positive end interface J3 of Li-Ion rechargeable battery group; The G end of P-MOS field effect transistor Q1 is connected with the other end of resistance R 1 and an end of resistance R 2; The other end ground connection of R2.

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