A kind of battery pack balancing protection system
Technical field
The utility model relates to power safety technique field, particularly relates to a kind of battery pack balancing protection system.
Background technology
Inconsistency is there is between each cell in battery pack, the difference that continuous print charge and discharge cycles causes, to the capacity of some cell be made to accelerate decay, the capacity of series battery be determined by the minimum capacity of cell, and therefore these differences shorten making the useful life of battery pack.Cause this unbalanced main cause to have: in cell fabrication processes, due to reasons such as techniques, capacity, internal resistance etc. with batch battery there are differences; The difference of battery self discharge rate, accumulates for a long time, causes the difference of battery capacity; In battery use procedure, environment for use, as the difference of temperature, circuit board, causes the imbalance of battery capacity; Before battery combination, owing to screening the imperfection of principle, the imbalance between the battery cell caused.Conventional balance charge/discharge technology has constant shunt resistance balance charge/discharge, break-make shunt resistance balance charge/discharge, average battery voltage balance charge/discharge, switching capacity balance charge/discharge, buck convertor balance charge/discharge, inductance balance charge/discharge etc.And existing single lithium battery protect IC is not all containing balance charge/discharge controlling functions; Multisection lithium battery protect IC equalizing charge controlling functions needs cpu peripheral; by realizing with the serial communication (as I2C bus) of protect IC, increasing complexity and design difficulty, the efficiency reducing system and the reliability of protective circuit, adding power consumption.
Summary of the invention
For correlative technology field document and above the deficiencies in the prior art, in a large amount of existing literature research with for a long time on the basis of association area Development Practice, the utility model proposes " a kind of battery pack balancing protection system ", overcome in prior art and " use in groups for ternary lithium battery, each joint lithium battery all requires overvoltage of charging, electric discharge under voltage, overcurrent, the protection of short circuit, the problem of whole Battery pack balance charge/discharge will be realized in charge and discharge process " etc. technical barrier, devise the battery pack protective circuit containing balanced charge-discharge function adopting the in groups lithium battery of single lithium battery protect IC to any serial number to protect, realize that " performance difference between effectively avoiding because of battery pack causes overcharging to cell or the phenomenon of over-discharge can, improve reliability and the energy conversion efficiency of system to greatest extent " beneficial effect.
For achieving the above object; the utility model is achieved through the following technical solutions: a kind of battery pack balancing protection system; this system lithium battery group, control circuit, main circuit and shunting discharge paths; described main circuit is connected with control circuit with discharge control switch device by charging control switch device; shunting discharge paths is connected to control circuit, and the single lithium battery of lithium battery group is connected in series.Described shunting discharge paths comprises the shunting discharge paths control switching device of charging overvoltage shunting discharge paths resistance and series connection with it.Described control circuit comprises over-current detection protective resistance, Li battery protection IC, charging control metal-oxide-semiconductor and control of discharge metal-oxide-semiconductor; the CO pin of each Li battery protection IC of described lithium battery group is connected respectively to charging control metal-oxide-semiconductor; the DO pin of each Li battery protection IC is connected respectively to control of discharge metal-oxide-semiconductor; be connected on main circuit after the VM pin series connection over-current detection protective resistance of each battery protection chip, between the VDD pin that the shunting discharge paths of each lithium battery is connected in series to corresponding Li battery protection IC and VSS pin.Described Li battery protection IC is connected in series by bus, protects respectively to the discharge and recharge of corresponding single lithium battery, overcurrent, short-circuit condition.Described Li battery protection IC controls the break-make of shunting discharge paths switching device.Charging voltage protecting control signal Parallel opertation after light-coupled isolation of described single lithium battery protect IC, for the charge switch break-over of device of main circuit provides grid step voltage.Discharge voltage protecting control signal Parallel opertation after light-coupled isolation of described single lithium battery protect IC, for the discharge switch break-over of device of main circuit provides grid step voltage.
A kind of battery pack balancing guard method comprises the following steps: step one, when part single lithium battery is in charging process, reach overvoltage protection state, be connected in parallel on the shunting discharge paths electric discharge at single lithium battery battery plus-negative plate two ends by overvoltage protection signal controlling, the corresponding single lithium battery dialysis be connected in charge circuit gone out charge circuit simultaneously; When all single lithium battery bulk charges enter overvoltage protection state, whole single lithium battery voltage swing is completely equal in error range, the equal step-down of each joint Li battery protection IC charge protection control signal, grid bias cannot be provided for the charging control switch device in main circuit, make it turn off, major loop disconnects, and namely realize equalizing charge, charging process completes; Step 2, when part single lithium battery under voltage or overcurrent and short circuit; corresponding single lithium battery discharge prevention control signal step-down, cannot provide grid bias for the discharge control switch device in main circuit, make it turn off; major loop disconnects, and namely terminates use procedure of discharging.
The beneficial effects of the utility model: single lithium battery protect IC uses according to ternary lithium battery cell number tandem, respectively to the discharge and recharge of corresponding single lithium battery, overcurrent, short-circuit condition is protected, controlled the break-make of shunting discharge paths switching device by protect IC simultaneously, and then realize the balance charge/discharge of BMS lithium electricity intelligent management unit, performance difference between this kind of cell equalizing protecting circuit effectively avoids because of battery pack causes overcharging to cell or the phenomenon of over-discharge can, improve reliability and the energy conversion efficiency of system to greatest extent.
Accompanying drawing explanation
Fig. 1 is the lithium battery group baffle schematic diagram possessing balance protection of the utility model specific embodiment;
Fig. 2 is the charging process schematic diagram of the utility model specific embodiment;
Fig. 3 is that the loading sharing of the utility model specific embodiment crosses schematic diagram;
Fig. 4 is the discharge process schematic diagram of the utility model specific embodiment.
Embodiment
Contrast accompanying drawing below, by the description to embodiment, to embodiment of the present utility model as involved control system, mutual annexation, and implementation method, be described in further detail, have more complete, accurate and deep understanding to help those skilled in the art to inventive concept of the present utility model, technical scheme.
A kind of battery pack balancing protection system; this system lithium battery group, control circuit, main circuit and shunting discharge paths; described main circuit is connected with control circuit with discharge control switch device by charging control switch device; shunting discharge paths is connected to control circuit, and the single lithium battery of lithium battery group is connected in series.Described shunting discharge paths comprises the shunting discharge paths control switching device of charging overvoltage shunting discharge paths resistance and series connection with it.Described control circuit comprises over-current detection protective resistance, Li battery protection IC, charging control metal-oxide-semiconductor and control of discharge metal-oxide-semiconductor; the CO pin of each Li battery protection IC of described lithium battery group is connected respectively to charging control metal-oxide-semiconductor; the DO pin of each Li battery protection IC is connected respectively to control of discharge metal-oxide-semiconductor; be connected on main circuit after the VM pin series connection over-current detection protective resistance of each battery protection chip, between the VDD pin that the shunting discharge paths of each lithium battery is connected in series to corresponding Li battery protection IC and VSS pin.Described Li battery protection IC is connected in series by bus, protects respectively to the discharge and recharge of corresponding single lithium battery, overcurrent, short-circuit condition.Described Li battery protection IC controls the break-make of shunting discharge paths switching device.Charging voltage protecting control signal Parallel opertation after light-coupled isolation of described single lithium battery protect IC, for the charge switch break-over of device of main circuit provides grid step voltage.Discharge voltage protecting control signal Parallel opertation after light-coupled isolation of described single lithium battery protect IC, for the discharge switch break-over of device of main circuit provides grid step voltage.
Use in groups for ternary lithium battery; each joint lithium battery all requires the protection of charging overvoltage, electric discharge under voltage, overcurrent, short circuit; the problem of whole Battery pack balance charge/discharge to be realized in charge and discharge process, devise the battery pack protective circuit containing balanced charge-discharge function adopting the in groups lithium battery of single lithium battery protect IC to any serial number to protect.
Lithium battery group cell equalizing protecting circuit basic functional principle as shown in Figure 1.Wherein: 1 is single-unit lithium ion battery; 2 is charging overvoltage shunting discharge paths resistance; 3 is shunting discharge paths control switching device; 4 is over-current detection protective resistance; 5 divide for abridged Li battery protection IC and circuit connecting section; 6 is single lithium battery protect IC (generally comprise charging and control pin CO, control of discharge pin DO, discharge over-current and short-circuit detecting pin VM, battery positive VDD, battery negative terminal VSS etc.); 7 drive in main circuit for charging overvoltage protection signal forms parallel relationship after light-coupled isolation the control metal-oxide-semiconductor grid that charges; 8 be electric discharge under voltage, overcurrent, short-circuit protection signal form series relationship and drive control of discharge metal-oxide-semiconductor grid in main circuit after light-coupled isolation; 9 is charging control switch device; 10 is discharge control switch device; 11 is control circuit; 12 is main circuit; 13 is shunting discharge paths.Single lithium battery protect IC number is determined according to lithium battery cell number, and series connection uses, and protects respectively to the discharge and recharge of corresponding single lithium battery, overcurrent, short-circuit condition.This system is while charge protection, and the break-make being controlled shunting discharge paths switching device by protect IC realizes balance charge/discharge.When lithium battery group is charged, external power supply both positive and negative polarity connects battery pack both positive and negative polarity BAT+ and BAT-two ends respectively, charging current flows through single lithium battery 1 ~ N in battery anode BAT+, battery pack, discharge control switch device, charging control switch device, battery electrode BAT-, and current direction as shown in Figure 2.
Charging overvoltage protection control signal Parallel opertation after light-coupled isolation of control circuit part single lithium battery protect IC in system, in main circuit, the conducting of charge switch device provides grid voltage; As a certain joint or a few joint lithium battery are introduced into overvoltage protection state in charging process; then be connected in parallel on the shunting discharge paths electric discharge of single lithium battery positive and negative end by overvoltage protection signal controlling, the corresponding single lithium battery dialysis be serially connected in charge circuit gone out charge circuit simultaneously.
During lithium battery group serial connection charge, ignore other impact of single battery capacity difference, the less battery of general internal resistance is first full of.Now, the switching device of corresponding overvoltage protection signal controlling shunting discharge paths closes, a shunt resistance in the parallel connection of primary cell two ends.According to the PNGV equivalent-circuit model of battery, now diverter branch resistance is equivalent to the load of the single lithium battery be first full of, and this battery, by its electric discharge, makes battery terminal voltage maintain near full state in a minimum scope.Suppose the first charging complete of Section 1 lithium battery, enter overvoltage protection state, then in main circuit and shunting discharge paths, current direction is as shown in Figure 3.When all single battery bulk charges enter overvoltage protection state; whole single lithium battery voltage swing is completely equal in error range; the equal step-down of each joint protect IC charge protection control signal; grid bias cannot be provided for the charging control switch device in main circuit; make it turn off; major loop disconnects, and namely realize equalizing charge, charging process completes.
When battery power discharge, external load connects battery pack both positive and negative polarity BAT+ and BAT-two ends respectively, discharging current flows through single lithium battery N ~ 1 and battery anode BAT+ in battery electrode BAT-, charging control switch device, discharge control switch device, battery pack, and current direction as shown in Figure 3.The electric discharge under voltage protection of control circuit part single lithium battery protect IC in system, overcurrent and short-circuit protection control signal are connected output after light-coupled isolation, in main circuit, the conducting of discharge switch device provides grid voltage; Once battery pack runs into single lithium battery under voltage or the special circumstances such as overcurrent and short circuit in discharge process; corresponding single lithium battery discharge prevention control signal step-down; grid bias cannot be provided for the discharge control switch device in main circuit; make it turn off; major loop disconnects, and namely terminates use procedure of discharging.
Single lithium battery protect IC uses according to ternary lithium battery cell number tandem; respectively the discharge and recharge of corresponding single lithium battery, overcurrent, short-circuit condition are protected; controlled the break-make of shunting discharge paths switching device by protect IC simultaneously; and then realize the balance charge/discharge of BMS lithium electricity intelligent management unit; performance difference between this kind of cell equalizing protecting circuit effectively avoids because of battery pack causes overcharging to cell or the phenomenon of over-discharge can, improves reliability and the energy conversion efficiency of system to greatest extent.
The utility model is not limited to above-mentioned specific embodiment; do not departing under the utility model spirit and real situation thereof; those of ordinary skill in the art can make various corresponding change and distortion according to the utility model; these are tackled amendment that the utility model carries out mutually or equivalently to replace, and it all should be encompassed in the middle of the scope of claim of the present utility model protection.