Lithium-ion battery charging key technology
Lithium battery storage devices ion energy on behalf of the development orientation of the spacecraft is the third generation storage device power spacecraft. It has a lightweight, small, no memory effect, to adjust to the temperature scale, etc., the main use of Ni-Cd, Ni-MH battery replacement. Lithium-ion batteries for the ratio of weight aerospace energy of 90 ~ 110Wh/kg compared to Ni-MH Laptop battery ~ 45 indicators 60Wh/kg have obvious advantages. However, the electrochemical properties of lithium-ion batteries that require charging process must be strictly controlled, therefore, to design a special circuit to monitor the management of lithium-ion battery ship loading process.
The lithium-Key-ion battery charger
Lithium-ion batteries replaced nickel-cadmium, Ni-MH battery can not be applied a “plug and play” approach, because the lithium-ion battery and Ni-Cd, Ni-MH battery has a very big difference: Lithium-overcharging ion is strictly prohibited. Therefore, we must combine the features of the design of new lithium-ion battery charging circuit for battery management. Lithium-ion battery circuit management charge of key points (with Ni-Cd, Ni-MH battery charge management circuitry main differences between points) is two main aspects: the mode of charging and load balanced.
In engineering applications, lithium-ion VGP-BPS10 battery monomer or from a single cell in parallel to form a battery module is held in tandem with the battery, it must take into account the process of charging the battery or a stack imbalance monomer unit, but as time passes, these imbalances will become increasingly serious, serious impact on battery life and reliability, equalization charge is also the key technologies for lithium - ion battery.
A constant voltage constant current - (TAPER) Charge Control Model
The introduction of nickel-cadmium, nickel-hydrogen battery power system by satellite, using essentially the current mode of constant load, when the curve reached VT, power electronics, pressure, the third electrode method command such as checkpoints to stop charging the completion of a charging process. Lithium battery ion control is not suitable for application of these methods, because the charge does not guarantee the lithium rechargeable ion batteries is always limited to the final pressure within limits, although the load is guaranteed final pressure is often pressure to reach the final load immediately after the termination of charging, lithium batteries, ion batteries to reach the final after fracturing must add about 30% of electricity. From the perspective of developing lithium-ion batteries for many years, a constant current - constant voltage charge command is the most common and most appropriate mode of load control. In this mode, the charger first lithium-ion batteries for charging at constant current when the VGP-BPS13 battery voltage is raised gradually when the battery voltage reaches the value set to a constant voltage charging, where the load current decreases approximately exponentially, so that kind of load, also known as TYPE-based load control.
2 load-balanced technologies
Aerospace lithium-ion battery charging technology must be balanced, this view has been fully recognized at home and abroad. A balanced technology is primarily responsible for resolving the long-term single lithium-ion battery charging process in the electrochemical properties of bias and, therefore, the merits of a balanced pricing will take some time, capital and investments are made to be effectively checked.
Lithium-ion battery equalization charging civilians in the product has not yet received widespread attention and application, because the multi-cell section is only rarely applied in series, reliability, durability and non - not ask for much. Lithium-ion batteries in electric vehicle system, the single cell series of other sessions, has adopted a balanced charging technology, the general system of microcomputer control is used in a single cell on a shunt resistor on the application running well-off and control the amount of a single battery charge. Such methods to control the complexity, low efficiency, heat consumption of large, balanced for a long period in the early program of aerospace products in the transplantation of this approach, the technical personnel at home and abroad studying now even more perfect.
The importance of a balanced load is to make lithium-ion battery voltage difference monomer remain in the expected range, thus ensuring the life of every cell in the satellite during the shocks are not subjected to stress too much damage. Without a balanced control costs, with the increase in charge-discharge cycle, the voltage of a single cell differentiated gradually.
Under normal circumstances, when the lithium-ion battery voltage difference load monomer within 50mV is perfectly acceptable. We believe that the main reason for discrepancies caused by an effective single battery charge, self-discharge rate is different. On the other hand, single cell in the circuit measuring the current consumption should also seriously consider the effects, sometimes consumed circuit current measurement has reached the size of the VGP-BPS11 battery discharge current. Experience life Lithium-Ion battery make, and some technical staff to reflect the first round of the battery is often only the first or last is damaged; it is often consumed as a result of the measurement circuit.