CN210074845U - Voltage-sharing circuit of series lithium batteries - Google Patents
Voltage-sharing circuit of series lithium batteries Download PDFInfo
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- CN210074845U CN210074845U CN201921426056.8U CN201921426056U CN210074845U CN 210074845 U CN210074845 U CN 210074845U CN 201921426056 U CN201921426056 U CN 201921426056U CN 210074845 U CN210074845 U CN 210074845U
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Abstract
The utility model discloses a series lithium battery voltage-sharing circuit, which comprises a battery pack consisting of an even number of lithium batteries which are connected in series in sequence, a high-frequency multiport transformer, a primary side half-bridge circuit and a plurality of secondary side half-bridge circuits; the half-bridge circuit at the primary side comprises an N-type switch tube SAN-type switch tube SAThe drain electrode of the capacitor is respectively connected with the anode of the battery pack and one end of a capacitor C1; n-type switch tube SARespectively with the inductor LP1One end of (2) and N-type switch tube SBThe drain electrodes of the first and second transistors are connected; n-type switch tube SBThe source of the capacitor is respectively connected with the cathode of the battery pack and one end of a capacitor C2; the other end of the capacitor C1 is connected to the primary winding TPIs connected to the other end of the capacitor C2; primary side coil TPAnother end of (1) and an inductor LP1The other ends of the two are connected. The utility model discloses circuit structure is simple, and is with low costs, has avoided single cell's among the lithium cell group minimum voltage to influence group battery effective capacity.
Description
Technical Field
The utility model relates to a lithium cell voltage-sharing field, concretely relates to series connection lithium cell voltage-sharing circuit.
Background
With the progress of the related technology of the battery, the lithium battery has the advantages of high energy density, environmental protection, no memory effect and the like, and is more and more widely applied to the energy storage link of a new energy distributed micro power generation network, the vehicle-mounted battery of a new energy electric vehicle and other occasions.
Because the voltage of the single lithium ion battery is relatively low, the load requirement of a high-power grade cannot be met in practical application, and a certain number of batteries are required to be connected in series to form a battery pack to meet the actual battery voltage requirement. However, the lithium ion battery is limited by the manufacturing process at the present stage and the influence of environments such as working temperature, and the like, and the problem that parameters such as battery capacity, equivalent internal resistance and the like are inconsistent occurs in the actual work of the lithium ion battery.
The voltage and remaining capacity of each battery is affected by its battery parameters. The inconsistency of the cell parameters in the battery pack directly results in inconsistency of the cell voltages and inconsistency of the remaining capacities within the same battery pack. The effective capacity of the battery pack mainly depends on the single battery with the lowest voltage in the battery pack, so that the service life and the use efficiency of the battery pack are influenced by the overlarge voltage difference of the single batteries in the same battery pack.
SUMMERY OF THE UTILITY MODEL
The above-mentioned not enough to among the prior art, the utility model provides a pair of series connection lithium cell equalizer circuit has solved the problem that the minimum voltage of monomer battery influences group battery effective capacity among the lithium cell group.
In order to achieve the purpose of the invention, the utility model adopts the technical scheme that:
provide aA series lithium battery voltage-sharing circuit comprises a battery pack consisting of an even number of lithium batteries which are sequentially connected in series, a high-frequency multi-port transformer, a primary side half-bridge circuit and a plurality of secondary side half-bridge circuits; the half-bridge circuit at the primary side comprises an N-type switch tube SAN-type switch tube SAThe drain electrode of the capacitor is respectively connected with the anode of the battery pack and one end of a capacitor C1; n-type switch tube SARespectively with the inductor LP1One end of (2) and N-type switch tube SBThe drain electrodes of the first and second transistors are connected; n-type switch tube SBThe source of the capacitor is respectively connected with the cathode of the battery pack and one end of a capacitor C2; the other end of the capacitor C1 is connected to the primary winding TPIs connected to the other end of the capacitor C2; primary side coil TPAnother end of (1) and an inductor LP1The other ends of the two are connected;
every two adjacent lithium batteries form a battery pack and correspond to a secondary side half-bridge circuit, and the mth secondary side half-bridge circuit comprises an N-type switching tube S2m-1N-type switch tube S2m-1The drain electrode of the battery pack is connected with the anode of the battery pack corresponding to the drain electrode; n-type switch tube S2m-1The source electrodes of the N-type switching tubes are respectively connected with the N-type switching tubes S2mDrain electrode and inductor L ofsmOne end of (a); inductor LsmThe other end of (2) and the secondary side coil TsmOne end of the two ends are connected; secondary side coil TsmThe other end of the positive electrode is connected to the positive and negative electrode series connection lines of the two corresponding lithium batteries; n-type switch tube S2mIs connected with the cathode of the corresponding battery pack.
Further, a primary side coil TPAnd an inductance LP1One end connected with the other end is a homonymous end; secondary side coil TsmAnd an inductance LsmThe end connected is the end with the same name.
The utility model has the advantages that: the utility model discloses circuit structure is simple, and is with low costs, and control mode is convenient, can realize battery energy transfer in the group battery, battery pack energy transfer and former vice limit energy transfer, and it can carry out the voltage-sharing to complicated voltage distribution's group battery, has avoided single battery's among the lithium cell group minimum voltage to influence group battery effective capacity.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention;
fig. 2 is a schematic diagram of the operation of the present invention for transferring energy in the battery pack;
FIG. 3 is a schematic diagram illustrating the operation of the present invention in transferring energy between battery packs;
FIG. 4 is a schematic diagram of the primary and secondary energy transfer of the present invention;
FIG. 5 is an equivalent waveform diagram of the operation of the present invention;
fig. 6 is a schematic view of the current mode of the working mode 1 of the present invention;
fig. 7 is a schematic view of the current mode of the working mode 2 of the present invention;
fig. 8 is a schematic view of the current mode of the working mode 3 according to the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and various changes will be apparent to those skilled in the art as long as they are within the spirit and scope of the present invention as defined and defined by the appended claims, and all inventions contemplated by the present invention are protected.
As shown in fig. 1, the voltage-sharing circuit for series-connected lithium batteries comprises a battery pack consisting of an even number of lithium batteries connected in series in sequence, a high-frequency multi-port transformer, a primary side half-bridge circuit and a plurality of secondary side half-bridge circuits; the half-bridge circuit at the primary side comprises an N-type switch tube SAN-type switch tube SAThe drain electrode of the capacitor is respectively connected with the anode of the battery pack and one end of a capacitor C1; n-type switch tube SARespectively with the inductor LP1One end of (2) and N-type switch tube SBThe drain electrodes of the first and second transistors are connected; n-type switch tube SBThe source of the capacitor is respectively connected with the cathode of the battery pack and one end of a capacitor C2; the other end of the capacitor C1 is connected to the primary winding TPIs connected to the other end of the capacitor C2; primary side coil TPAnother end of (1) and an inductor LP1The other ends of the two are connected;
every two adjacent lithium batteries form a battery pack and correspond to a secondary side half-bridge circuit, and the mth secondary side half-bridge circuit comprises an N-type switching tube S2m-1N-type switch tube S2m-1The drain electrode of the battery pack is connected with the anode of the battery pack corresponding to the drain electrode; n-type switch tube S2m-1The source electrodes of the N-type switching tubes are respectively connected with the N-type switching tubes S2mDrain electrode and inductor L ofsmOne end of (a); inductor LsmThe other end of (2) and the secondary side coil TsmOne end of the two ends are connected; secondary side coil TsmThe other end of the positive electrode is connected to the positive and negative electrode series connection lines of the two corresponding lithium batteries; n-type switch tube S2mIs connected with the cathode of the corresponding battery pack.
Primary side coil TPAnd an inductance LP1One end connected with the other end is a homonymous end; secondary side coil TsmAnd an inductance LsmThe end connected is the end with the same name.
In the specific implementation process, the utility model discloses an equivalent oscillogram of work is shown in fig. 5, the utility model discloses a voltage-sharing circuit topology essence is single inductance voltage-sharing and multiport DC-DC converter transmission energy. In various working states, three different energy transmission modes are presented.
As shown in fig. 2, the first operating state is energy transfer in the battery pack, the voltage of the battery (or capacitor) is detected, if the voltage of the upper battery is higher than the voltage of the lower battery, the switch tube corresponding to the upper battery is opened during the duty cycle, at this time, the upper battery discharges through the inductor, the inductor accumulates energy, the inductor current freewheels after the duty cycle is over, and the energy is released to the lower battery with low voltage. The battery with the positive electrode of the single lithium battery in each battery pack as the positive electrode of the battery pack is an upper battery, and the battery with the negative electrode of the single lithium battery in each battery pack as the negative electrode of the battery pack is a lower battery. Taking a secondary side half-bridge circuit (Module 1) as an example, which is fully drawn in fig. 1, a battery B is shown1For charging the battery, the corresponding switch tube is the switch tube S1Battery B in the drawing2For the lower battery, the corresponding switch tube is the switch tubeS2。
As shown in fig. 3, the second operating state is energy transfer between battery packs, and the secondary side half-bridge circuit is connected by a high frequency multi-port transformer, which constitutes a ratio of 1: 1: …: 1 multiport DC-DC converter. At the same time, the battery pack with the battery voltage higher than the secondary side voltage of the transformer discharges to the transformer, and the transformer charges the battery pack with the battery voltage lower than the voltage of the transformer. After a plurality of cycles, the cell voltages of the respective battery packs tend to be equal.
As shown in fig. 4, the third operating state is energy balance between the single body and the whole body, the secondary side half-bridge circuit and the primary side half-bridge circuit are connected together through a high frequency multi-port transformer, and the ratio of the components is n: 1: …: 1, unlike the second approach. The current of the secondary side half-bridge circuit is still determined by the cell voltage of each battery pack and the voltage of the high-frequency multi-port transformer, and the primary side current is the same as the value of the sum of all the battery pack currents on the secondary side after the sum is converted by the high-frequency multi-port transformer. The current on the primary side charges and discharges the whole battery pack through the upper bus and the lower bus, and the energy of the whole battery pack is exchanged.
In one embodiment of the present invention, when the transformer voltage is lower than all the battery cell voltages, all the secondary side half-bridge circuits are discharged to the high frequency multi-port transformer, so that the current of the primary side half-bridge circuit is the sum of all the secondary side half-bridge circuits. In this mode, the current flowing direction of the whole topology is single and fixed, which is beneficial for analysis, so that the analysis is performed by taking this mode as an example and combining the voltage and current waveform and the circuit mode diagram. In the mode, in order to make all the batteries voltage-sharing to the average voltage, only the switch tube corresponding to the battery with the voltage higher than the average voltage is switched on.
As shown in fig. 6, the operation mode 1: detecting the upper battery in each battery pack at the secondary side at t0And (4) at the moment, opening secondary side switch tubes in the first j battery packs with the upper battery voltage higher than the average voltage. At this time, the corresponding opening switch tube S on the primary sideAEnergy flows from all upper cells in the first j cell groups to pass through eachSelf-corresponding switch tube gives inductance Ls1…LsjCharging ils1…ilsjLinearly rising while transferring energy to the primary side, i, through a high frequency multiport transformerLpLinearly rising through the switching tube SAEnergy is transferred to the integral battery pack. The rear k windings of the secondary side of the high-frequency multiport transformer are also provided with induced voltage VTSBut V is caused by the setting of the transformer transformation ratioTS<VBk1+VDSo that Sk1The body diode of (1) is not turned on. There is no current path. This stage enables the transfer of individual battery energies to the overall battery pack.
As shown in fig. 7, the operation mode 2: t is t1At the moment, the first j odd-numbered switching tubes S1…S2j-1And a switching tube SASimultaneously turning off, and respectively passing through S by the energy stored in the high-frequency multi-port transformer inductorAAnd j odd number switching tubes S1…S2j-1The primary side of the diode continues current through a switch tube SAThe diode is released to the whole battery pack, and the secondary side passes through the front j even-numbered switch tubes S1…S2j-1The diode of (a) discharges to the lower cell in the group corresponding to the upper cell discharged in the previous cycle. At this stage, the secondary side realizes single inductor voltage sharing in the secondary side half-bridge circuit, and the primary side realizes the transmission of inductor energy to the whole. Although the discharge speed of the inductor is high or low due to the difference of the battery voltages of the secondary side half-bridge circuits, the secondary side half-bridge circuits can slowly continue to flow in dead time along with the advance of time, and at t, the secondary side half-bridge circuits can slowly continue to flow in dead time2At the moment, all the secondary side half-bridge circuits complete follow current, and only the excitation current still exists in the circuit. The stage realizes the release of the stored energy of the inductor to the low-voltage battery, and is the next half stage of single inductor voltage sharing.
As shown in fig. 8, the operation mode 3: the stage is a follow current stage of the exciting current, and the exciting current can only pass through the capacitor C2 and the switch tube S because the high-frequency multiport transformer is already out of workBBody diode and primary side inductor LP1And then follow current. Will switch the tube SBIs clamped to zero, and the switching tube S is realized at the moment t3BThe soft switching of (1). The discharge of energy from the high voltage battery to the entire battery pack and the low voltage battery in the pack during the next half cycle is initiated.
To sum up, the utility model discloses circuit structure is simple, and is with low costs, and control mode is convenient, can realize battery energy transfer in the group battery, battery pack energy transfer and former vice limit energy transfer, and it can carry out the voltage-sharing to complicated voltage distribution's group battery, has avoided single cell's among the lithium cell group minimum voltage to influence group battery effective capacity.
Claims (2)
1. A series lithium battery voltage-sharing circuit is characterized by comprising a battery pack consisting of an even number of lithium batteries which are sequentially connected in series, a high-frequency multiport transformer, a primary side half-bridge circuit and a plurality of secondary side half-bridge circuits; the primary side half-bridge circuit comprises an N-type switch tube SAThe N-type switch tube SAThe drain electrode of the capacitor is respectively connected with the anode of the battery pack and one end of a capacitor C1; the N-type switch tube SARespectively with the inductor LP1One end of (2) and N-type switch tube SBThe drain electrodes of the first and second transistors are connected; the N-type switch tube SBThe source of the capacitor is respectively connected with the cathode of the battery pack and one end of a capacitor C2; the other end of the capacitor C1 is connected to the primary winding TPIs connected to the other end of the capacitor C2; the primary side coil TPAnother end of (1) and an inductor LP1The other ends of the two are connected;
every two adjacent lithium batteries form a battery pack and correspond to a secondary side half-bridge circuit, and the mth secondary side half-bridge circuit comprises an N-type switching tube S2m-1The N-type switch tube S2m-1The drain electrode of the battery pack is connected with the anode of the battery pack corresponding to the drain electrode; the N-type switch tube S2m-1The source electrodes of the N-type switching tubes are respectively connected with the N-type switching tubes S2mDrain electrode and inductor L ofsmOne end of (a); the inductance LsmThe other end of (2) and the secondary side coil TsmOne end of the two ends are connected; the secondary side coil TsmThe other end of the positive electrode is connected to the positive and negative electrode series connection lines of the two corresponding lithium batteries; the N-type switch tube S2mIs connected with the cathode of the corresponding battery pack。
2. A voltage equalizing circuit for series lithium batteries according to claim 1, wherein said primary winding T is formed of a metal materialPAnd an inductance LP1One end connected with the other end is a homonymous end; the secondary side coil TsmAnd an inductance LsmThe end connected is the end with the same name.
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| CN201921426056.8U CN210074845U (en) | 2019-08-29 | 2019-08-29 | Voltage-sharing circuit of series lithium batteries |
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| CN201921426056.8U CN210074845U (en) | 2019-08-29 | 2019-08-29 | Voltage-sharing circuit of series lithium batteries |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110380493A (en) * | 2019-08-29 | 2019-10-25 | 西南交通大学 | A kind of serial lithium battery equalizer circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110380493A (en) * | 2019-08-29 | 2019-10-25 | 西南交通大学 | A kind of serial lithium battery equalizer circuit |
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