CN106451686A - Battery pack equalization circuit - Google Patents

Abstract

The invention belongs to the technical field of battery pack management systems, and specifically relates to a battery pack equalization circuit, which includes a multi-winding transformer and a battery pack connected in series by batteries. The multi-winding transformer includes a first side coil and a second side coil. The first The number of side coils is consistent with the number of batteries, and a first side coil is connected in parallel with a battery after being connected in series with a semiconductor switch, and a second side coil is connected in parallel with a battery pack after being connected in series with a diode. Through the multi-winding transformer, the energy of the battery pack is transferred from the high-voltage battery to the low-voltage battery, so that the battery pack can be quickly and evenly charged and discharged, and the energy consumption in the equalization process can be reduced. The structure is simple and easy to implement.

Description

Battery Pack Balancing Circuit

technical field

The invention belongs to the technical field of battery pack management systems, and in particular relates to a battery pack equalization circuit.

Background technique

The consistency of lithium-ion batteries is very important to the management system of lithium-ion battery packs. If the lithium-ion batteries are not balanced, the battery with the highest voltage will be fully protected first when charging, resulting in the other batteries in the entire battery pack not being fully charged, and the battery with the lowest power when discharging. Empty first, resulting in remaining power of other batteries, and finally the actual available power of the battery pack is much less than the sum of the single and parallel batteries. The capacity of the battery pack is not fully utilized.

The current advanced battery management system will have a battery balancing circuit to make up for the above shortcomings. The current technology is mainly divided into two categories: passive equalization and active equalization. The first type of passive equalization, energy dissipation equalization, uses the method of parallel connection of resistors to a single parallel battery to discharge the battery that consumes excess power, a large amount of energy is lost, heat is generated, and Heat further deteriorates the battery working environment. The equalizing current is small and cannot quickly balance the battery.

The second type is active equalization technology, which mainly uses transformer energy conversion, and there are only two energy conversion directions. The first type is to transfer energy from single-parallel batteries to battery packs, and the second is to transfer energy from battery packs to single-parallel batteries. And accurate sampling data and strategies are needed to control the transfer direction. If there is a deviation in the balance of the acquisition, there will be confusion.

Contents of the invention

The purpose of the present invention is to address the shortcomings of the prior art, to realize fast equalization of the battery pack, and to reduce the energy loss of the battery pack.

In order to achieve the above object, the present invention adopts the following technical solutions:

The battery pack balancing circuit includes a multi-winding transformer and a battery pack connected in series by batteries, the multi-winding transformer includes a first side coil and a second side coil, the number of the first side coils is consistent with the number of batteries, and a first The side coil is connected in series with the semiconductor switch and then connected in parallel with a battery, and the second side coil is connected in series with the diode and connected in parallel with the battery pack.

As an improvement of the battery pack balancing circuit of the present invention, the number of turns of each of the first side coils is the same.

As an improvement of the battery pack balancing circuit of the present invention, the winding ratio of the first side coil and the second side coil is 1:5.

As an improvement to the battery pack balancing circuit of the present invention, the multi-winding transformer is a flyback transformer.

The beneficial effects of the present invention are: to provide a battery pack balancing circuit, including a multi-winding transformer and a battery pack formed by batteries connected in series, the multi-winding transformer includes a first side coil and a second side coil, and the number of the first side coils is the same as that of the second side coil The number of batteries is the same, and a first side coil is connected in parallel with a battery after being connected in series with a semiconductor switch, and a second side coil is connected in parallel with a battery pack after being connected in series with a diode. Through the multi-winding transformer, the energy of the battery pack is transferred from the high-voltage battery to the low-voltage battery, so that the battery pack can be quickly and evenly charged and discharged, and the energy consumption in the equalization process can be reduced. The structure is simple and easy to implement.

Description of drawings

FIG. 1 is a schematic diagram of the circuit structure of the present invention.

detailed description

The present invention and its beneficial effects will be further described in detail below in conjunction with specific embodiments, however, the specific embodiments of the present invention are not limited thereto.

As shown in Figure 1, the battery pack equalization circuit includes a multi-winding transformer and a battery pack formed by batteries connected in series. There are n batteries, which are respectively batteries B1-Bn. The second side coils, the number of the first side coils is the same as the number of batteries, which are respectively the first side coils C1~Cn, and the first side coils C1~Cn are respectively connected to the batteries B1~Bn after being connected in series with semiconductor switches K1~Kn In parallel connection, the second side coil is Cn+1, and the second side coil Cn+1 is connected in parallel with the battery pack after being connected in series with the diode D1.

The equalization process is as follows, assuming that the battery B1 is a battery unit with a higher voltage, and the battery B3 is a battery unit with a lower voltage. At the same time, the semiconductor switches K1 and K3 are closed, the battery B1 is connected to the first side coil C1, and the battery B3 is connected to the first side coil C3. The battery B1 magnetizes the transformer through the first side coil C1, and the magnetic field generates an induced voltage on the first side coil C3 equal to the voltage of the battery B1. Therefore, the first side coil C3 will charge the battery B3, and this process completes the energy transfer from the battery B1 to the battery B3 at one time. Then the semiconductor switches K1 and K3 are turned off, and the magnetic field is reset through the diode D1 and the second side coil Cn+1. Then continue to repeat the previous steps to continuously complete the energy transfer from battery B1 to B3. In the same way, energy transfer between arbitrary batteries can be realized. And the transmission direction is fixed as high voltage transmission to low voltage. If the semiconductor switches K1 to Kn are all turned on at the same time, the energy can also be transferred in the whole battery pack at the same time, and the energy is transferred from the high-voltage battery to the low-voltage battery, so as to achieve the self-balancing convergence function.

As an improvement of the battery pack balancing circuit of the present invention, the number of turns of each of the first side coils is the same.

As an improvement of the battery pack balancing circuit of the present invention, the winding ratio of the first side coil and the second side coil is 1:5.

As an improvement to the battery pack balancing circuit of the present invention, the multi-winding transformer is a flyback transformer.

According to the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also change and modify the above embodiment. Therefore, the present invention is not limited to the above-mentioned specific implementation manners, and any obvious improvement, substitution or modification made by those skilled in the art on the basis of the present invention shall fall within the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (4)

1. circuit of battery pack balancing it is characterised in that：The set of cells be connected into including multiwinding transformer and by battery, described Multiwinding transformer includes the first lateral coil and the second lateral coil, and described first lateral coil quantity is consistent with number of batteries, and one First lateral coil connect with semiconductor switch after with a cell parallel, the second lateral coil and Diode series after with set of cells simultaneously Connection.

2. circuit of battery pack balancing according to claim 1 it is characterised in that：The winding number of turn of each described first lateral coil Identical.

3. circuit of battery pack balancing according to claim 1 it is characterised in that：Described first lateral coil and described second side The winding turn ratio of coil is 1：5.

4. circuit of battery pack balancing according to claim 1 it is characterised in that：Described multiwinding transformer becomes for inverse-excitation type Depressor.