Digital battery

4 single cells linear charge voltage limit advanced control

single cell have been sampled by the voltage control circuit of each cell, through or remove a single cell maximum gate voltage after the signal conversion circuit in the control circuit of the limited pressure circuit control limits of power management voltage by dynamically adjusting the impedance control of lithium-ion battery voltage of the single cell. If neither a single cell voltage reaches the value set, the solar panel to the relatively stable current through the pressure limiting control circuit in the power management of the lithium-ion battery charging, management Food of the impedance is close to zero, when everything just a single battery voltage reaches the set value, increases the impedance of the power transistor, battery charge current decreases with decreasing load current by laws characteristics of lithium-ion decision (approximately exponential). This circuit has the advantage of a constant voltage charging phase of the continuous flow decreases, essentially exponentially, compared to adapt lithium-ion battery charging habits, the load circuit power as well. Dell Vostro 1220 battery Dell Vostro 1220n battery

 

Several load equalization technology

 

A shunt resistance constant load balanced

 

All Lithium-ion single time on a shunt resistor in parallel. As can be seen on the circuit, the current shunt resistor must be greater than the battery self-discharge current to reach the equilibrium charge effects. General lithium-ion battery self-discharge current C/20000, it is flowing through the shunt resistor on the current catch C/200 is more appropriate.

 

In addition, the difference of each resistor shunt is also an important factor affecting equalization. After a number of charge cycles and discharge gap of a single cell can be determined using the following formula:

gap V battery voltage = I × R shunt one battery discharge gap 2 × V × K resistance

If the shunt resistor to 20Ω ± 0.05%, the bias voltage of the battery to control the range 50mV. Mean power of each resistor 0.72W, but whatever the battery charge or discharge the battery, always consume power shunt resistor. Dell Inspiron 1470 battery Dell Inspiron 1470n battery

 

Level 2 charging off-balance sheet resistance shunt

 

resistance segregation of charge balance and exceptional charge the difference between equilibrium segregation resistance is increased by a switch off, the switch can be controlled by a software system computer to achieve, but also a simple logic circuit can be achieved. This control method uses a balanced circuit in the perception of constant tension working TYPE section, other times switch broke, it needs to discharge the battery, the shunt resistor does not consume valuable energy. In the phase of light, the solar power generation, there is a surplus, and consume little energy for the balancing system of the supply circuit for a certain rationality. In the orbit of satellites in low orbit, the circuit balanced only 10% of working time in order to obtain a balanced effect discussed above, the value of resistance must be reduced by 10 times, shows the peak power thermal is very high, this circuit is the main drawback. In addition, the effectiveness of extinguishing a fatal failure, redundancy means must be used. Dell Inspiron 14z battery Dell Inspiron 1570 battery

 

Switched-capacitor charge balance 3

 

principle switched capacitor charge balance in Figure 7, we can see from the figure, the order of the circuit control switch is composed of clock circuits, causing a closure order multi-switch, the order to send a capacitor of the lithium-ion single entry by sending imbalance between the energy of a single cell to achieve the goal of equalizing charge. At the same time, by measuring the voltage on the capacitor voltage sent to monitor every single cell. If one cell short-circuit failure, low voltage output of the comparator switching prohibition to prohibit access to short-circuit transfer capacitor cell to eliminate the influence of the work of bodies unicellular others in the same time for constant voltage converter in a constant current battery low voltage alarm, so that constant current constant voltage converter circuit according to the situation of a single cell to determine the correct constant voltage. The biggest advantage of this symmetrical circuit is very low energy loss, a disadvantage is that circuit complexity, multi-switch on resistance, high common-mode limit will affect the achievement of a balanced load. On the other hand, the selection of parameters is difficult to configure different power system, the circuit parameters of the detailed design and verification requirements, which is detrimental to the development cycle. Dell Inspiron 1570n battery Dell Inspiron 15z battery

 

4 buck converter load equalization

 

Buck converter is also a balanced load of a balanced program of low consumption. It is a very clear idea of the main circuit is a standard buck regulator, the inductor energy to increase the subgroups of the same winding, the auxiliary monomer to charge the battery. Clearly, low voltage single cell will get more energy second winding, the high voltage energy to get less, if the goal of achieving a balanced load. To get a good balance of effects, sub-winding consistency requires strict control. However, the consistency of the inductor winding is very difficult to control, if it is one of the biggest weaknesses of control like. This study has just started charging, the charging efficiency, balanced results, reliability analysis requires further study.

 

The average balance of cell charging voltage 5

 

The average cell voltage balance charging principle illustrated in figure 9, the figure only shows a single cell in a symmetrical circuit, the other single cell is also equipped with the same balanced circuit, which, starting from a single amplifier cell. dell latitude d810 battery dell latitude d820 battery

 

The control circuit of load balancing of thought is as follows: single cell voltage and average voltage of a single cell from the control switch to the battery voltage is higher than the average single cell voltage of the shunt. Therefore, all voltages unicellular symmetrization of the average voltage of a cell under trend.

 

At first glance, this circuit is the open loop control, in fact, the internal resistance of the battery as the role of balanced circuits work in a negative feedback loop characteristic states. Balanced to avoid work-circuit the battery discharge, the power switch in the bottom of the diode series regulator, so that the discharge of the battery, the battery voltage is low and the loss branch circuit. dell latitude d620 battery dell latitude d800 battery

 

The model of the average cell voltage balance charging circuit is a comprehensive study, is considered a highly effective program. This circuit has been included in the orbit of LEO satellites of choice for applications in lithium-ion program, has filed patents in France and Europe.

 

Conclusion

 

Discussed above, the lithium-ion battery charging circuit management key technologies: constant current - constant voltage (cone) the method of load and load-balanced technology. In comparison, our point of view, the “single-cell linear voltage peak” limiting load control programs more compatible with the use of small satellites, can avoid the pass-type control consumption of significant heat, “Split”, a huge pulse of current load control, “subtype” constant voltage charging phase of the load current reduces the gap discontinuity, the average cell voltage balance charging circuit adaptable all indicators are ideal. dell latitude d600 battery dell latitude d610 battery