1. Shunt resistance constant load balanced
Every single lithium-ion batteries in parallel on both a shunt resistor. As seen from the circuit, the shunt resistor current must exceed the battery discharge current to reach a balanced load effect. General lithium-ion battery discharge current C/20000 as such, it flows through the shunt resistor on the current use C/200 is more appropriate.
In addition, each effects bias shunt resistance are also important factors affecting the balance. After a number of load cycles of discharge, the difference of a single cell can be determined using the following formula:
V battery voltage shunt type = R × I self-discharge 2 × V × single cell polarization resistance K
If the shunt resistance to 20Ω ± 0.05%, while the gap voltage Laptop battery can be controlled to within 50mV range. The average power of each resistor 0.72W, but whatever the process of loading the battery or the process of discharging the battery, shunt resistor still consume energy.
2. Removed balance shunt resistor
Equilibrium Charge-off shunt resistor shunt with the difference in resistance between the equalizing charge is adding an on-off switch, this button switch can be achieved by the SCM system software can also be done by a simple logic circuit to achieve. Circuits using this control method only charge balanced type a constant voltage phase of work, other times on-off switch is always off, so the discharge of the battery needed, the shunt resistor does not consume valuable energy. In the period lighting, solar energy production, there is a surplus, when a balanced circuit consumes a certain energy to the system power supply to a certain degree of rationality. In the orbit of satellites in low orbit, such a balanced circuit only 10% of working time in order to obtain a balanced effect discussed above, the resistance value is necessary to reduce by 10 times, showing that the peak Thermal power is very large, it is such a circuit the main drawback. In addition, the effectiveness of on-off switch is a fatal failure, it is necessary that the redundancy of resources.
3 Switched-capacitor charge balances
one can see from the table, sequence switching circuit driver mainly by the clock circuits, which drive multi-channel change the order of closure, the The order of lithium-ion VGP-BPS10 battery access monomer transmission capacitor, by transmitting the imbalance between the energy of a single cell to achieve a balanced application of load. At the same time, by measuring the voltage on the capacitor sent to monitor every single cell voltages. If one cell short circuit fault occurs at low output voltage comparator to switch ban signals, prohibit access to short-circuit the battery to send a single capacitor, to avoid affecting the activities normal cell only alternative to both the constant current constant voltage converter in the battery low voltage alarm, so that constant current constant voltage converter in a single cell to short-circuit conditions to determine the constant voltage correct. The biggest advantage of this circuit is a balanced energy waste is very low, the drawback is that the circuit complex, multi-way switch on resistance state, the upper limit of common mode will affect the achievement a balanced load. On the other hand, the selection of parameters is difficult, a different configuration of power system, the circuit parameters required for detailed design and verification, which is detrimental to the development cycle.
4. step-down converter load equalization
Buck Converter is also a balance of low power charging solution for the rest of the program. It is very good idea, the main circuit is a standard male-type regulator in the inductor energy to add multiple sets of the same sub-windings, for single auxiliary VGP-BPS13 battery charge. Clearly, the low voltage single cell sub-windings more energy, a high voltage to be less energy, so that the aim of achieving a balanced load. To achieve a good balance of effects, sub-windings of the coherence of the need for strict control. However, the consistency of the inductor winding is very difficult to master, so it’s such a control method of a greater disadvantage. This study has just started to load, efficiency, balance of performance, reliability analysis, the need to continue in the study.
5. The average balance of tension load cells
The average balance of cell voltage charging principles as shown, 1 shows only a single cell balance circuit, the only other cell is also equipped with an identical balanced circuit, from which a single battery-powered amplifier.
Such a balanced load control circuit of thought is: single-cell voltage and medium voltage single cell compared to the control power switch to the battery voltage is above the average voltage of segregation unicellular. Therefore, all tension of the single cell balancing under the effect of the circuit tends to power the cell average.
At first glance, this circuit is the open loop control, in fact because of the role of the VGP-BPS11 battery internal resistance, a balanced circuit with negative feedback characteristics in the state closed loop. To prevent discharge circuit of the battery in a time of balanced work, you can reduce the power regulator switching diodes in series, so that the discharge of the battery, the battery voltage is low and the loss of shunt circuit.
The average balance of cell charging voltage circuit model has in-depth study is considered the result of a very good program. This circuit has been included in the LEO orbit lithium-ion battery applications, the preferred program, filed a patent application in France and Europe.