A battery balancing circuit and its control method

Abstract

The invention discloses a battery balancing circuit and a control method thereof. The battery balancing circuit includes a first balancing circuit, second balancing circuits, freewheel loops, first sampling circuits and a timer. The first balancing circuit is used for transmitting power of a charging circuit and a battery set to the second balancing circuits. The second balancing circuits are used for transmitting the power, transmitted from the first balancing circuit, to batteries connected with the same; the freewheel loops are used for freewheeling currents of inductors in the second freewheel circuits. The first sampling circuits are used for constantly sampling current voltages of the batteries connected with the same. The timer is used for timely sending signals to the first balancing circuit to allow periodic on-off of the first balancing circuit. The first balancing circuit is parallelly connected with the battery set. The first sampling circuits are connected with the batteries respectively. After parallelly connected to two ends of each battery, each second balancing circuit is electrically connected with the first balancing circuit. The freewheel loops are connected with the second balancing circuits and the batteries respectively, wherein, the second balancing circuits are connected with the batteries. The timer is electrically connected with the first balancing circuit.

Description

technical field [0001] The invention relates to a battery protection system, in particular to a battery balancing circuit and a control method thereof. Background technique [0002] For a battery pack containing multiple batteries, each battery has a different aging rate, different temperature, and uneven charge and discharge capacity, which often leads to a mismatch between the capacity of some battery cells and other battery cells in the battery pack in series, which in turn leads to the failure of the entire battery pack. capacity mismatch. When charging, other battery cells in series have not been fully charged yet, and the aging battery cell has been fully charged. When discharging, other battery cells have not been fully discharged, and the rapidly aging battery has been discharged, forming a barrel effect and restricting the performance of the entire battery pack. If a battery system is left to operate under these conditions and is not managed, the service life of t...

AI Technical Summary

Problems solved by technology

Due to the small voltage difference between the battery cells, the transfer speed is very slow, which cannot meet the real-time requirements of large current discharge, and the charge can only be transferred between adjacent battery cells, which reduces the transfer efficiency.

[0005] like figure 2 As shown, the switch of another equalization circuit generally adopts semiconductor MOSFET or relay switch, for example figure 1 , figure 2 Among them, the switch S is generally acted by a MOSFET or a relay. The main problem of the relay is that the switching speed is too slow, generally about 5ms, which makes the power transfer speed slow, and the MOSFET needs a driving circuit, and the driving circuit needs a source that is better than the driven MOSFET. The extremely high voltage is 7~10V. If this voltage is taken from the battery unit through the converter, it will not only increase the complexity, but also reduce the efficiency.

As the number of battery cells in series increases, the problem becomes more prominent. In addition, the circuit also has the problem that energy can only be transferred between adjacent cells. When the capacities of non-adjacent battery cells do not match, multiple transfers are required to Passing from a high-capacity battery to a low-capacity battery reduces transfer efficiency

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