Method and circuit for dynamically equalizing battery management system

Abstract

The invention relates to a method and a circuit for dynamically equalizing a battery management system. The method comprises the following steps of: 1) detecting the voltage of each single battery in each group of battery packs sequentially connected in series by using embedded control software; 2) judging the location number of the single battery which needs to be charged or discharged separately and has excessively low or high voltage by using a central processing unit (CPU); 3) giving a control command out by using the CPU, controllably gating a corresponding polarity selecting switch block to perform polarity inversion on a collection bus, controllably gating a corresponding battery selecting switch block to perform polarity matching at the same time, controlling the working direction of a bidirectional isolation transformer and connecting the single battery which needs to be charged or discharged separately and has the excessively low or high voltage to the connection bus for charging or discharging so as to realize energy transfer; and 4) repeating the steps 1) to 3) until the voltage of each single battery in each group of battery packs sequentially connected in series is in a set allowable error range so as to realize dynamic equilibrium. The number of charging and discharging devices and circuit complexity of the battery management system can be reduced remarkably.

Description

technical field [0001] The invention relates to a battery management system, in particular to a dynamic equalization method and a dynamic equalization circuit for the battery management system. Background technique [0002] There are many solutions for the existing iron-lithium battery management system. The most commonly used is the use of figure 1 The energy balance circuit shown is simple and practical. Through the voltage regulator tubes D1, ... Dn or other control circuits of S1, ... Sn, which are switches respectively, when the voltage of a single battery BT1 or BTn is too high, it is automatically turned on. The bypass branch of a single battery BT1 or BTn provides a shunt to reduce the current flowing through the battery BT1 or BTn and avoid overvoltage of the battery BT1 or BTn. The disadvantage is that the energy loss is large, and the resistance needs to be dissipated. It can only be used for In low power circuits; such as figure 2 The energy-transfer balancin...

AI Technical Summary

Problems solved by technology

The most commonly used is to use such as figure 1 The energy balance circuit shown is simple and practical. Through the voltage regulator tubes D1, ... Dn or other control circuits of S1, ... Sn, which are switches respectively, when the voltage of a single battery BT1 or BTn is too high, it is automatically turned on. The bypass branch of a single battery BT1 or BTn provides a shunt to reduce the current flowing through the battery BT1 or BTn and avoid overvoltage of the battery BT1 or BTn. The disadvantage is that the energy loss is large, and the resistance needs to be dissipated. It can only be used for In low power circuits; such as figure 2 The energy-transfer balancing circuit shown can be used in large and medium power circuits. The low-voltage battery 2 can be charged separately through the conversion circuit, or the high-voltage battery 5 can be discharged separately through the conversion circuit, so that each single battery 1 ~6 The voltage is within the controllable range, and its defect is that it can only be used in a circuit with a small number of batteries connected in series. Otherwise, the conversion circuit uses too many bidirectional switches and its control circuit, the cost is too high, and the transformer taps of the conversion circuit are too many , it is difficult to implement and apply on a large scale

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