A kind of protective circuit of power lithium-ion battery
Technical field
The utility model belongs to the electric components technical field, relates to a kind of protective circuit of power lithium-ion battery.
Background technology
When lithium ion battery uses as electrokinetic cell, often need the above lithium ion battery series connection of 5 joints be used, to reach the required voltage of motor.When it being charged with charger, because the quality of every batteries can not be just the same,, just possibly cause inter-electrode short-circuit in case there is a batteries to be in overcharge condition, influence battery capacity, in the life-span, cause battery explosion, peril generation such as on fire.Simultaneously, battery is in to the external loading power supply process, and its voltage can reduce along with power supply process gradually, crosses low even capacity when being given out light fully when cell voltage, possibly cause the permanent damage of battery.In addition, the powered battery electric current is excessive also safety problem can occur.
At present, for the protective circuit of the above lithium ion battery group of 5 joints, all be to adopt a cover to detect decision circuitry to every batteries, adopt a plurality of battery protection chips to be in series, cost is high, poor reliability.Therefore when studying the series connection of multi-section lithium ion battery and using, can be simultaneously to every batteries overcharge, the circuit of overdischarge, overcurrent, short-circuit protection is extremely important.
The utility model content
The utility model technical problem to be solved provides a kind of protective circuit of power lithium-ion battery; When the series connection of multi-section lithium ion battery is used; Can be simultaneously to every batteries overcharge, overdischarge, overcurrent, short-circuit protection, reduce production costs, enhance productivity.
The technical solution of utility model is following:
A kind of protective circuit of power lithium-ion battery comprises battery pack, first metal-oxide-semiconductor and second metal-oxide-semiconductor that microprocessor, 5 joint lithium ion batteries are in series; The positive pole of said battery pack connects the positive output end of power lithium-ion battery, and the negative pole of battery pack connects the source electrode of first metal-oxide-semiconductor, and the drain electrode of first metal-oxide-semiconductor connects the drain electrode of second metal-oxide-semiconductor, and the source electrode of second metal-oxide-semiconductor connects the negative output terminal of power lithium-ion battery; 10 IO ports of said microprocessor in twos one group through 5 cover capacitance-resistance filter branch roads respectively with battery pack in 5 single batteries be connected; The grid of first metal-oxide-semiconductor and second metal-oxide-semiconductor all is connected with microprocessor; First metal-oxide-semiconductor has first body diode, and second metal-oxide-semiconductor has second body diode; The positive pole of first body diode and negative pole connect the source electrode and the drain electrode of first metal-oxide-semiconductor respectively, and the positive pole of second body diode and negative pole connect the source electrode and the drain electrode of second metal-oxide-semiconductor respectively; The negative pole end of microprocessor and battery pack is connected with delay capacitor.
The span of resistance is 300~470 ohm in the said capacitance-resistance filter branch road.
Beneficial effect:
The protective circuit of the utility model power lithium-ion battery, when multi-section lithium ion battery series connection is used, can be simultaneously to every batteries overcharge, overdischarge, overcurrent, short-circuit protection, reduce production costs, enhance productivity.
Below in conjunction with accompanying drawing the utility model is done further to describe in detail.
Description of drawings
Fig. 1 is the protective circuit structured flowchart figure of the utility model power lithium-ion battery.
Embodiment
Below will combine accompanying drawing and specific embodiment that the utility model is explained further details:
As shown in Figure 1, a kind of protective circuit of power lithium-ion battery comprises battery pack, first metal-oxide-semiconductor and second metal-oxide-semiconductor that microprocessor, 5 joint lithium ion batteries are in series; The positive pole of said battery pack connects the positive output end of power lithium-ion battery, and the negative pole of battery pack connects the source electrode of first metal-oxide-semiconductor, and the drain electrode of first metal-oxide-semiconductor connects the drain electrode of second metal-oxide-semiconductor, and the source electrode of second metal-oxide-semiconductor connects the negative output terminal of power lithium-ion battery; 10 IO ports of said microprocessor in twos one group through 5 cover capacitance-resistance filter branch roads respectively with battery pack in 5 single batteries be connected; The grid of first metal-oxide-semiconductor and second metal-oxide-semiconductor all is connected with microprocessor; First metal-oxide-semiconductor has first body diode, and second metal-oxide-semiconductor has second body diode; The positive pole of first body diode and negative pole connect the source electrode and the drain electrode of first metal-oxide-semiconductor respectively, and the positive pole of second body diode and negative pole connect the source electrode and the drain electrode of second metal-oxide-semiconductor respectively; The negative pole end of microprocessor and battery pack is connected with delay capacitor C.
Microprocessor is set and is saved in the internal storage unit battery parameter according to the specifications and models of the battery pack that adopts.When battery was in normal operating conditions, two metal-oxide-semiconductors all were in conducting state, and each batteries in the battery pack can freely be charged and discharge.
Microprocessor uninterruptedly detects each monomer battery voltage; Data in detected data and the memory cell are compared; When microprocessor detects among VCC1~VCC5 one of them voltage and surpasses 4.25V~4.30V is overcharge condition, and 2 pin output low levels of microprocessor are closed second metal-oxide-semiconductor; Cut-out is to the charging of battery pack; Guaranteed that arbitrary joint cell can not damage because of overcharging, because the existence of the body diode VD2 that second metal-oxide-semiconductor carries, battery can discharge through this diode pair external loading.
Detect cell voltage at microprocessor and surpass 4.28V to sending between the shutoff second metal-oxide-semiconductor signal, also have one section delay time, the length of this delay time is determined by C, is made as usually about 1 second, to avoid causing erroneous judgement disconnected because of interference.
In battery discharge procedure; When microprocessor detects that one of them voltage is lower than 2.3V among VCC1~VCC5; Its 1 pin will change no-voltage into by high voltage, make first metal-oxide-semiconductor transfer shutoff to by conducting, thereby cut off discharge loop; Battery can't be discharged to load again, play the over effect.And this moment because the existence of the body diode VD1 that carries of first metal-oxide-semiconductor, charger can charge through this diode pair battery.Detect cell voltage at microprocessor and be lower than 2.3V to sending between the shutoff first metal-oxide-semiconductor signal, one section delay time is also arranged, the length of this delay time is determined by C, is made as usually about 100 milliseconds, to avoid causing erroneous judgement disconnected because of interference.
In addition microprocessor can detect battery pack to the load discharge process in, the loop current that each batteries is corresponding judges whether to take place overcurrent and protection phenomenon; In case take place; Can close end first metal-oxide-semiconductor rapidly, thereby cut off discharge loop, play overcurrent and protective effect.
This protective circuit also is suitable for the battery pack use that the above lithium ion battery of 5 joints is in series.
If require charge protection voltage to surpass 4.30V, the size of adjustable resistor R1~R5 reaches desired condition, and the span of resistance R 1~R5 is 300~470 ohm.