CN217469473U

CN217469473U - Double-modular parallel equalizer for series storage battery system

Info

Publication number: CN217469473U
Application number: CN202123053778.3U
Authority: CN
Inventors: 刘红锐; 韦向阳; 李海瑞
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2021-12-07
Filing date: 2021-12-07
Publication date: 2022-09-20
Anticipated expiration: 2031-12-07

Abstract

The utility model discloses a double modular parallel equalizer of a series battery system, which comprises a first equalizing module LBM, a second equalizing module FBM, a battery system and an equalizing voltage source BE; the battery system is composed of series-connected battery units BU, each of which is composed of two series-connected single batteries. The utility model discloses possess four big advantages at least: the method has the advantages that firstly, the equalizer can realize parallel equalization when performing first and second equalization, the equalization speed is high, and the equalizer is not easily influenced by the number of single batteries; secondly, the components in the whole equalization circuit are few and easy to control; thirdly, a modular design is adopted, the parameters of the switch device are unchanged, the expansion is easy, and the voltage stress of each switch tube is small; and fourthly, the driving voltage of the switches in all the equalizing modules is provided by the battery unit or the equalizing voltage source, and an additional driving power supply is not needed.

Description

Double-modular parallel equalizer for series storage battery system

Technical Field

The utility model relates to a parallel equalizer of dual modularization of series connection battery system belongs to power electronic technology and the balanced management technical field of battery energy.

Background

With the increasing severity of environmental pollution and energy crisis, in order to solve these problems, the global power grid industry, manufacturing industry, transportation industry and other industries begin to move towards low energy consumption, low pollution and low carbonization, and a double-carbon strategy is also put forward in China. The energy storage battery technology is a key technology for solving the problems, so that the rapid development of the electric automobile can be promoted, and the intellectualization of a large-scale distributed power grid is promoted. The lithium ion battery has the characteristics of high energy density, low self-charging and discharging rate, long cycle life, flexible grouping mode and the like, and is widely applied to the fields of electric automobiles, intelligent power grids, communication equipment and the like.

The nominal voltage of the lithium ion single battery is about 3.6v, and in order to meet the voltage requirement of the storage battery system, a plurality of single batteries are connected in series to form the battery system. The overcharge or overdischarge of the single battery will affect the service life of the battery and the battery system, even an explosion accident occurs, so that when a plurality of single batteries are used in series, the overdischarge and overcharge states of any single battery are not allowed. Due to the performance difference of the single batteries, the energy of the single batteries is inconsistent in the use process, the single battery with high energy limits the charging capacity of the whole battery system, the single battery with low energy limits the discharging capacity of the whole battery system, the charging capacity and the discharging capacity of the battery system are gradually reduced along with the increase of the charging and discharging cycle times of the battery system, and finally the battery system is scrapped in advance. In order to increase the charge and discharge capacity of the battery system and prolong the service life of the battery, active and effective balancing measures must be taken for the series single storage batteries.

In order to solve the problem of inconsistent energy among single batteries in a battery system, a storage battery equalization circuit is developed. The equalization circuit mainly comprises an active equalization circuit and a passive equalization circuit. The active equalization circuit transfers energy through an inductor, a capacitor, a transformer and other energy storage elements. The passive equalization circuit consumes the redundant energy of the single battery with high energy through energy consumption elements such as resistors. From the perspective of energy conservation and emission reduction, active equalization has great advantages, and meanwhile, the equalization mode of active equalization is more flexible and the equalization effectiveness is better.

The existing active equalization generally has the following main problems:

1. the equalization speed is limited by the number of cells in series. The larger the number of the single batteries connected in series is, the lower the equalizing speed is;

2. the energy transfer loop is long, and the balance efficiency is low. The single battery is used as a balance object, when the single battery has arbitrary selectivity and energy bidirectionality, the lithium ion single battery with the nominal voltage of 3.6v has more switching devices in an energy loop, and the balance efficiency is low;

3. the modularization degree is weak, when the number of the series-connected batteries needs to be increased, the voltage stress of the switching device in the equalizer is changed, and the parameters of the switching device are reselected.

Disclosure of Invention

The utility model provides a parallel equalizer of two-fold modularization of series connection battery system to be used for constructing the parallel equalizer of two-fold modularization of series connection battery system through modular two-fold balanced module, and further realize the energy balance between the inside two battery cells of all battery units through two-fold equilibrium, realize the energy balance between each series connection battery unit through three kinds of mode.

The technical scheme of the utility model is that: a dual modular parallel equalizer for a series battery system comprises a first equalizing module LBM, a second equalizing module FBM, a battery system and an equalizing voltage source BE; the battery system is composed of battery units BU connected in series, and each battery unit is composed of two single batteries connected in series;

the port 1 and the port 3 of the ith first balancing module LBMi are respectively connected with the positive electrode and the negative electrode of the ith battery unit BUi, and the port 2 of the LBMi is simultaneously connected with the negative electrode of the single battery B (2i-1) and the positive electrode of the single battery B (2i) in the battery unit BUi;

the port A and the port B of the ith second equalization module FBMi are respectively connected with the port 1 and the port 3 of the ith first equalization module LBMi, and the port C and the port D of the FBMi are respectively connected with the anode and the cathode of an equalization voltage source BE; wherein i is 1,2,3, …, n; and n is the number of the battery units connected in series in the battery system, so that the number of the single batteries connected in series in the battery system is 2 n.

The first balancing module LBM consists of two power switches M1 and M2 with anti-parallel diodes and an inductor L, one end of the inductor L is used as a port 2 of the first balancing module LBM, and the other end of the inductor L is connected with the drain electrode of the power switch M1 and the drain electrode of the power switch M2; the source of the power switch M1 is set as port 1 of the first balancing module LBM, and the source of the power switch M2 is set as port 3 of the first balancing module LBM.

The second balancing module FBM consists of a flyback transformer FT, two power switches M3 with anti-parallel diodes and M4; the dotted terminal of the primary winding of the flyback transformer FT is used as the port a of the second balancing module FBM, the non-dotted terminal of the primary winding of the flyback transformer FT is connected to the drain of the power switch M3, the source of the power switch M3 is used as the port B of the second balancing module FBM, the non-dotted terminal of the secondary winding of the flyback transformer FT is used as the port C of the second balancing module FBM, the dotted terminal of the secondary winding of the flyback transformer FT is connected to the drain of the power switch M4, and the source of the power switch M4 is used as the port D of the second balancing module FBM.

The power switch M1 is a P-channel MOSFET, and its driving voltage is provided by the corresponding battery unit BU; power switch M2 is an N-channel MOSFET whose driving voltage is provided by the corresponding battery unit BU.

The power switches M3 and M4 are both N-channel MOSFETs, wherein the driving voltage of the power switch M3 is provided by the corresponding battery unit BU, and the driving voltage of the power switch M4 is provided by the balanced voltage source BE.

The utility model has the advantages that: the utility model discloses constructed duplicate equilibrium, first duplicate equilibrium is carried out with first equalization module, because every first equalization module is mutually independent, so each first equalization module can be parallel work simultaneously when carrying out the first duplicate equilibrium, the equilibrium is fast, the energy loop is short simultaneously, and adopt the complementary PWM control with the blind spot, the equilibrium is efficient, the first duplicate equalization circuit is simple, easy to control, easy to realize; the second equalization is performed by using the second equalization modules, and each second equalization module is independent, so that the equalization modules can simultaneously and parallelly work, the equalization speed is high, and the influence of the number of the batteries connected in series is basically avoided. The first re-equalization and the second re-equalization are both in modular design, the voltage stress of a switching device is low, and when the number of the series single batteries is increased, the parameters of the switching device are not changed, and only corresponding equalization modules are needed to be added; the whole equalizer circuit is simple and easy to control, and the driving voltage of the switching element in the equalization module is from a voltage source in the equalization system, so that the equalizer is easy to realize; therefore, the equalizer has the advantages of high equalization speed, high equalization efficiency, strong modularization, easy expansion, simple equalizer circuit, easy control and easy realization.

To sum up, the utility model discloses possess four big advantages at least: the method has the advantages that firstly, the equalizer can realize parallel equalization when performing first and second equalization, the equalization speed is high, and the equalizer is not easily influenced by the number of single batteries; secondly, the components in the whole equalization circuit are few and easy to control; thirdly, a modular design is adopted, the parameters of the switch device are unchanged, the expansion is easy, and the voltage stress of each switch tube is small; and fourthly, the driving voltage of the switches in all the equalizing modules is provided by the battery unit or the equalizing voltage source, and an additional driving power supply is not needed.

Drawings

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

FIG. 2 is a diagram of an equalization circuit for transferring energy from cell B (2i-1) to cell B (2i) in a first cell for heavy energy equalization;

FIG. 3 is a diagram of an equalization circuit for transferring energy from cell B (2i) to cell B (2i-1) in a first cell of a first gravimetric equalization;

FIG. 4 is a diagram of an equalization circuit during parallel equalization discharge of a plurality of high-energy battery cells for a second energy equalization; indicating that energy flows from battery units BU1 and BU2 to flyback transformers FT1 and FT 2;

fig. 5 is a diagram of an equalizing circuit when a plurality of high-energy battery cells of the second energy equalization are discharged in parallel in an equalizing manner; indicating that energy is flowing from flyback transformers FT1 and FT2 to balanced voltage source BE;

fig. 6 is an equalizing circuit diagram of a second energy equalization when a plurality of high-energy battery cells are discharged in parallel; a PWM timing signal diagram representing the power switches 1M3, 1M4, 2M3, 2M 4;

FIG. 7 is a diagram of an equalizing circuit for a second energy equalization in which a plurality of low-energy cells are equalized in parallel; indicating that energy is flowing from the balanced voltage source BE to the flyback transformers FT1 and FT 2;

FIG. 8 is a diagram of an equalizing circuit for a second energy equalization in which a plurality of low-energy cells are equalized in parallel; indicating the transfer of energy from flyback transformers FT1 and FT2 to battery units BU1 and BU 2;

fig. 9 is an equalizing circuit diagram of a second energy equalization when a plurality of low-energy battery cells are equalized and charged in parallel; a PWM timing signal diagram representing the power switches 1M3, 1M4, 2M3, 2M 4;

fig. 10 is a diagram of an equalizing circuit when a plurality of high-energy battery cells of the second energy equalization are discharged in parallel and equalized while a plurality of low-energy battery cells are charged in parallel and equalized; indicating that energy flows from battery units BU1 and BU2 to flyback transformers FT1 and FT2, and energy flows from balanced voltage source BE to flyback transformers FT3 and FT 4;

fig. 11 is a diagram of an equalizing circuit in the case of parallel equalizing discharge of a plurality of high-energy battery cells while parallel equalizing charge of a plurality of low-energy battery cells in the second energy equalization; indicating that energy flows from flyback transformers FT1 and FT2 to balanced voltage source BE, energy is transferred from flyback transformers FT3 and FT4 to battery units BU3 and BU 4;

fig. 12 is a diagram of an equalizing circuit in the case where a plurality of high-energy battery cells are discharged in parallel and equalized while a plurality of low-energy battery cells are charged in parallel and equalized in the second energy equalization; a PWM timing signal diagram of power switches 1M3, 1M4, 2M3, 2M4, 3M3, 3M4, 4M3, and 4M4 is shown.

(in FIGS. 1 to 12, black indicates an ON state and gray indicates an OFF state)

Detailed Description

The invention will be further described with reference to the following drawings and examples, but the scope of the invention is not limited thereto.

Example 1: as shown in fig. 1 to 12, a dual modular parallel equalizer for a series battery system includes a first equalizing module LBM, a second equalizing module FBM, a battery system, and an equalizing voltage source BE; the battery system is composed of battery units BU connected in series, and each battery unit is composed of two single batteries connected in series;

Further, the first balancing module LBM may be configured to include two power switches M1 and M2 with anti-parallel diodes, and an inductor L, where one end of the inductor L is used as the port 2 of the first balancing module LBM, and the other end of the inductor L is connected to the drain of the power switch M1 and the drain of the power switch M2; the source of the power switch M1 is set as port 1 of the first balancing module LBM, and the source of the power switch M2 is set as port 3 of the first balancing module LBM.

Further, the second balancing module FBM may be configured to be composed of a flyback transformer FT, two power switches M3 and M4 with anti-parallel diodes; the dotted terminal of the primary winding of the flyback transformer FT is used as the port a of the second balancing module FBM, the non-dotted terminal of the primary winding of the flyback transformer FT is connected to the drain of the power switch M3, the source of the power switch M3 is used as the port B of the second balancing module FBM, the non-dotted terminal of the secondary winding of the flyback transformer FT is used as the port C of the second balancing module FBM, the dotted terminal of the secondary winding of the flyback transformer FT is connected to the drain of the power switch M4, and the source of the power switch M4 is used as the port D of the second balancing module FBM.

Further, the power switch M1 and the power switch M2 in the first balancing module LBM may be both enhancement type power MOSFETs.

Further, the power switch M3 and the power switch M4 in the second balancing module FBM may be enhancement power MOSFETs.

Further, the equalizing voltage source BE may BE provided by the battery system via DC/DC or by a battery pack other than the battery system.

Further, the power switch M1 may be configured as a P-channel MOSFET, and its driving voltage is provided by the corresponding battery unit BU; power switch M2 is an N-channel MOSFET whose driving voltage is provided by the corresponding battery unit BU. The power switch M1 adopts a P-channel MOSFET, and the power switch M2 is an N-channel MOSFET, so that the driving voltage of the P-channel MOS tube and the driving voltage of the N-channel MOS tube are both provided by the battery unit conveniently by matching the P-channel MOSFET and the N-channel MOSFET, and the complementary PWM control is facilitated

Further, the power switch M3 and the power switch M4 may BE both N-channel MOSFETs, where the driving voltage of the power switch M3 is provided by the corresponding battery unit BU, and the driving voltage of the power switch M4 is provided by the balanced voltage source BE. The power switch M3 and the power switch M4 adopt N-channel MOSFETs, and the power switches and the MOSFET are switched by adopting specific MOSFETs, so that energy transfer between the battery unit and the balanced voltage source can be conveniently realized.

The utility model discloses an equalizer can adopt following control mode to carry out the equilibrium: the equalization process is divided into two equalization processes, wherein the first equalization process is realized by a first equalization module, the second equalization process is realized by a second equalization module on the premise of finishing the first equalization process.

The first rebalancing specifically includes:

all the first balancing modules can work simultaneously to realize energy balance between two single batteries in all the battery units: when the energy between the two single batteries B (2i-1) and B (2i) inside the ith battery unit BUi is unbalanced, the energy balance between the single batteries B (2i-1) and B (2i) is realized through the first balancing module LBMi; when the energy of the single battery B (2i-1) is high and the energy of the single battery B (2i) is low: performing PWM control on the power switch iM1, and simultaneously performing PWM control with dead zone complementation on the power switch iM2, wherein energy is transferred from the single battery B (2i-1) to the single battery B (2 i); when the energy of the cell B (2i) is high and the energy of the cell B (2i-1) is low: the power switch iM2 is PWM controlled, and meanwhile, the power switch iM1 is PWM controlled with dead zone complementation, and energy is transferred from the single battery B (2i) to the single battery B (2 i-1). That is, all the first balancing modules can work simultaneously, and all the battery units can be balanced by adopting the above method, and when the first balancing modules work, the power switches in the second balancing modules are in an off state.

The PWM control of the power switch iM1 and the PWM control with dead-zone complementation of the power switch iM2 are specifically: in the continuous current mode of the inductor Li, in any PWM control period, when the power switch iM1 is in the on state, the power switch iM2 is in the off state; when the power switch iM1 is in an off state, the power switch iM2 is turned on after passing through a dead zone until the next on time of the power switch iM1 is advanced by a dead zone to make the iM2 in an off state; the PWM control is performed on the power switch iM2, and the same PWM control with the dead zone complementary is performed on the power switch iM 1. That is, the time when the power switch iM1 is in the off state needs to satisfy that the power switch iM2 can be turned on after passing through a dead zone, and the power switch iM1 is turned on until the next turn-on time of the power switch iM1 is advanced by a dead zone so that the iM2 is in the off state.

By adopting a PWM control mode with dead zone complementation to iM1 and iM2, the problem of inaccurate signal control caused by action delay in the control process of a switching element can be solved, and short circuit in the process of transferring energy from one single battery to another single battery is avoided, so that the energy can be effectively transferred and is more practical, and meanwhile, the energy loss can be reduced; furthermore, energy recirculation can be avoided.

The second rebalancing specifically comprises:

the second balancing module realizes the energy balance among the series battery units through the mutually independent second balancing modules; the second equalization has three operation modes: the method comprises the following steps that a plurality of high-energy battery units are in parallel equalizing discharge, a plurality of low-energy battery units are in parallel equalizing charge, and a plurality of high-energy battery units are in parallel equalizing discharge and a plurality of low-energy battery units are in parallel equalizing charge; one of the three working modes is selected arbitrarily according to the energy difference between the series-connected battery units; the second equalization is carried out on the premise of finishing the first equalization, the second equalization is realized by a second equalization module, and when the second equalization module works, a power switch in the first equalization module is in a turn-off state;

a plurality of high-energy battery units are in parallel and are discharged in an equalizing way: a plurality of battery units with high energy in the battery system are subjected to parallel balanced discharge through respective second balancing modules; when the power switch iM3 in the second balancing module FBMi is PWM controlled, iM4 is always in an off state, and energy is transferred from the battery unit BUi to the balancing voltage source BE; (if the average voltage of cell BUi (i.e., half of the sum of the two cell voltages) is higher than the average voltage of the entire battery system, then the cell is considered to be a high energy cell);

a plurality of battery units with low energy are equalized and charged in parallel: a plurality of battery units with low energy in the battery system are subjected to parallel equalizing charging through respective second equalizing modules; when the power switch iM4 in the second balancing module FBMi is PWM controlled, iM3 is always in an off state, and energy is transferred from the balancing voltage source BE to the battery unit BUi; (if the average voltage of cell BUi is lower than the average voltage of the entire battery system, then the cell is considered a low energy cell);

the method comprises the following steps of (1) carrying out parallel equalizing discharge on a plurality of high-energy battery units and simultaneously carrying out parallel equalizing charge on a plurality of low-energy battery units: the battery system comprises a plurality of battery units with high energy, a plurality of battery units with low energy, a plurality of balancing modules and a plurality of balancing modules, wherein the plurality of battery units with high energy in the battery system are in parallel balanced charging through the second balancing modules; the power switch iM3 in the second balancing module FBMi is PWM controlled, and at the same time, the power switch jM4 in the second balancing module FBMj is PWM controlled, and the power switch iM4 and the power switch jM3 are always in an off state, and at the same time, energy is transferred from the battery cell BUi to the balancing voltage source BE, and energy is transferred from the balancing voltage source BE to the battery cell BUj.

Still further, the present invention provides the following:

regarding the first re-equalization:

as shown in fig. 2, when the energy of the cell B (2i-1) is high and the energy of the cell B (2i) is low: the switch iM1 is PWM controlled while energy flows from the battery cell B (2i-1) to the inductor Li, while the switch iM2 is PWM controlled with dead band compensation while energy is transferred from the inductor Li to the battery cell B (2 i).

As shown in fig. 3, when the energy of the cell B (2i) is high and the energy of the cell B (2i-1) is low: the switch iM2 is PWM controlled, where energy flows from the battery cell B (2i) to the inductor Li, while the switch iM1 is PWM controlled with dead band compensation, where energy is transferred from the inductor Li to the battery cell B (2 i-1).

Regarding the second re-equalization:

a plurality of high-energy battery units are in parallel balanced discharge: as shown in fig. 4-6, assuming high energy of battery units BU1 and BU2, parallel equalization discharge by respective second equalization modules is required. PWM controlling the power switches 1M3 and 2M3 in the second equalization modules FBM1 and FBM 2; as shown in fig. 4, energy is stored by the battery units BU1 and BU2 flowing to the corresponding flyback transformers FT1 and FT 2; as shown in fig. 5, energy flows from flyback transformers FT1 and FT2 to the balanced voltage source BE; fig. 6 shows PWM timing diagrams of power switches 1M3, 1M4, 2M3, and 2M 4.

Parallel equalizing charge of a plurality of battery units with low energy: as shown in fig. 7-9, assuming that the battery units BU1 and BU2 are low in energy, parallel equalization charging by respective second equalization modules is required. When the power switches 1M4 and 2M4 in the second equalization modules FBM1 and FBM2 are PWM controlled; as shown in fig. 7, energy is stored in the flyback transformers FT1 and FT2 by the balanced voltage source BE; as shown in fig. 8, energy is transferred from flyback transformers FT1 and FT2 to battery units BU1 and BU 2; as shown in fig. 9, PWM timing signal diagrams of the power switches 1M3, 1M4, 2M3, 2M 4.

The method comprises the following steps of (1) carrying out parallel equalizing discharge on a plurality of high-energy battery units and simultaneously carrying out parallel equalizing charge on a plurality of low-energy battery units: as shown in fig. 10-12, assuming that the energy of the battery units BU1 and BU2 is high, and the energy of the battery units BU3 and BU4 is low, the battery units BU1 and BU2 are required to be equally discharged in parallel through respective second equalizing modules, and the battery units BU3 and BU4 are required to be equally charged in parallel through respective second equalizing modules. While PWM-controlling the power switches 1M3 and 2M3 in the second equalization modules FBM1 and FBM2, PWM-controlling the power switches 3M4 and 4M4 in the second equalization modules FBM3 and FBM 4; as shown in fig. 10, energy is stored in the flyback transformers FT1 and FT2 by the battery units BU1 and BU2, and energy is stored in the flyback transformers FT3 and FT4 by the balanced voltage source BE; as shown in fig. 11, energy flows from the flyback transformers FT1 and FT2 to the balancing voltage source BE at the same time, and energy is transferred from the flyback transformers FT3 and FT4 to the battery units BU3 and BU 4; as shown in fig. 12, PWM timing signal diagrams of power switches 1M3, 1M4, 2M3, 2M4, 3M3, 3M4, 4M3, and 4M 4.

The present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit and scope of the present invention.

Claims

1. A dual modular parallel equalizer for series battery systems, comprising: the system comprises a first balancing module LBM, a second balancing module FBM, a battery system and a balancing voltage source BE; the battery system is composed of battery units BU connected in series, and each battery unit is composed of two single batteries connected in series;

2. The dual modular parallel equalizer for series battery systems of claim 1, wherein: the first balancing module LBM consists of two power switches M1 and M2 with anti-parallel diodes and an inductor L, wherein one end of the inductor L is used as a port 2 of the first balancing module LBM, and the other end of the inductor L is connected with the drain electrode of the power switch M1 and the drain electrode of the power switch M2; the source of the power switch M1 is set as port 1 of the first balancing module LBM, and the source of the power switch M2 is set as port 3 of the first balancing module LBM.

3. The dual modular parallel equalizer for series battery systems of claim 1, wherein: the second balancing module FBM consists of a flyback transformer FT, two power switches M3 with anti-parallel diodes and M4; the dotted terminal of the primary winding of the flyback transformer FT is used as the port a of the second balancing module FBM, the non-dotted terminal of the primary winding of the flyback transformer FT is connected to the drain of the power switch M3, the source of the power switch M3 is used as the port B of the second balancing module FBM, the non-dotted terminal of the secondary winding of the flyback transformer FT is used as the port C of the second balancing module FBM, the dotted terminal of the secondary winding of the flyback transformer FT is connected to the drain of the power switch M4, and the source of the power switch M4 is used as the port D of the second balancing module FBM.

4. The dual modular parallel equalizer of series battery systems as in claim 2, wherein: the power switch M1 is a P-channel MOSFET, and its driving voltage is provided by the corresponding battery unit BU; power switch M2 is an N-channel MOSFET whose driving voltage is provided by the corresponding battery unit BU.

5. The dual modular parallel equalizer for series battery systems of claim 3, wherein: the power switch M3 and the power switch M4 are both N-channel MOSFETs, wherein the driving voltage of the power switch M3 is provided by the corresponding battery unit BU, and the driving voltage of the power switch M4 is provided by the balanced voltage source BE.