|
In recent years, lithium battery has been more and more universal attentionand use, however monomer of lithium battery output power is limited, so in needhigh power output, need the large number of single cells in series, in parallelcombination become power battery. But in the manufacturing process due to themanufacturing process, battery materials, internal resistance and environmentaltemperature difference will lead to battery internal monomer battery series appearbetween voltage imbalance phenomenon, in use process, can cause a monomerbattery charging and discharging phenomenon, serious influence the service lifeof the battery power. In order to ensure the battery performance and prolong thelife of the battery, power battery equalization control study is very necessary.Existing balance control method is used mostly switch capacitance, bypassresistor, transformation circuit directly to a single way of power battery monomerbattery for balance control, though the way is simple in structure, cost is low waitfor an advantage, but as a result of power battery is consists of a large amount ofmonomer battery after series and parallel combinations and become, the internalelectric property is very complicated, lead to equilibrium process havedegeneration, nonlinear and uncertainty characteristics, so the above method hasthe obvious flaw, that is unable to power battery accurately balanced control, alsocan not carry out equalization algorithm further optimization.In view of this, this paper proposes a fuzzy control based on the combinedcell equilibrium system, based on MOSFET as inverter power switch tube,choose half bridge inverter topology structure and Cuk since the equalizationcircuit, built combined cell equalizer. Adopting digital control technology, designwith C8051F020MCU as the core of the control system, the use of C8051F020MCU to sampling signal processing, the realization to the battery balance ofclosed loop control, and on the basis of the balance control algorithm design.Will power battery complicated equilibrium control problem is simplified basedon pulse width modulation mode of dual mode control model of fuzzy control problem. Fuzzy control with double input and single output control structure, themonomer battery series maximum unbalanced degree E and charging current I asa control input, will drive signal of the duty ratio D as control output, andseparately carried on the controller without load static equilibrium situation andloading dynamic equilibrium situation of simulation.The test results show that, in view of the arbitrary input error voltage signalvalue or load current value balance can determine the real-time control output,the proposed control algorithm can better solve the power battery equalizationprocess degeneration, nonlinear and uncertainty problems, and improve thecontrol accuracy.
|