CN115800449A - Battery pack charging control method based on improved Buck-Boost equalization circuit - Google Patents
Battery pack charging control method based on improved Buck-Boost equalization circuit Download PDFInfo
- Publication number
- CN115800449A CN115800449A CN202211519544.XA CN202211519544A CN115800449A CN 115800449 A CN115800449 A CN 115800449A CN 202211519544 A CN202211519544 A CN 202211519544A CN 115800449 A CN115800449 A CN 115800449A
- Authority
- CN
- China
- Prior art keywords
- battery
- battery pack
- switch tube
- batteries
- switch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention relates to a battery pack charging control method based on an improved Buck-Boost equalizing circuit, wherein a battery pack consisting of 4 single batteries is used as a basic unit for balance control among groups, the battery pack is internally balanced in electric quantity by using an in-group equalizing circuit, and the balance and charging between every two battery packs are realized by adopting an inter-group equalizing circuit and a flyback transformer between the battery pack and any other battery pack. According to the invention, the electric quantity balance among any battery packs is realized, the flexibility of electric quantity balance of the battery pack is increased, the battery balance efficiency is improved, unnecessary middle batteries are prevented from participating in the electric quantity balance process, the loss of a switching tube and the loss of electric energy are reduced, and the battery balance time and the battery charging time are reduced; the method realizes the concurrent control of the inter-group balance and the battery pack charging, and improves the charging and balancing efficiency of the battery pack.
Description
Technical Field
The invention belongs to the field of battery charging and discharging control, and particularly relates to a battery pack charging control method based on an improved Buck-Boost equalizing circuit.
Background
With the rapid development of large-scale energy storage systems, the development of battery energy storage is also faster and faster. In order to meet the requirements of large capacity and high power, the single batteries are often used in a series-parallel combination mode, but due to the difference of the internal structures of the batteries and the difference of the environmental temperature, the charge-discharge rate, the self-discharge rate and the like in the using process, the existing inconsistency among the single batteries is larger in the using process. The inconsistency between batteries easily causes overcharge and overdischarge of the batteries, and long-time overcharge and overdischarge not only can cause the service life of the batteries to be reduced, but also can cause the damage and explosion of the batteries more seriously. Therefore, it is very important to have an excellent balancing technique to improve the capacity utilization rate and the use efficiency of the battery and ensure the safe and sustainable work of the battery pack.
The battery balancing technology mainly comprises two parts of battery balancing topology and balancing control strategy. The conventional Buck-Boost equalization circuit has some problems. On one hand, in the process of battery equalization, energy of a traditional equalization circuit must be sequentially transmitted among single batteries, so when the number of batteries needing equalization is large, the overall equalization efficiency is greatly reduced, and the use of the batteries is seriously influenced. On the other hand, because only adjacent cells can be equalized sequentially, when two cells that are not adjacent and have a large energy difference are to be equalized, the cells that do not need to be equalized are charged and discharged cumulatively, and extra power loss is generated.
The topological circuit for step-by-step balancing among the groups is researched, energy is transferred through an inductor by a Buck-Boost circuit in the groups, charging of different groups of batteries is achieved by a flyback converter among the groups, extra power loss caused by repeated charging and discharging of certain batteries is improved by the aid of the balanced topology, and balancing time and loss of a switching tube are greatly reduced.
Disclosure of Invention
The invention aims to solve the problems and provides a battery pack charging control method based on an improved Buck-Boost equalizing circuit, a battery pack consisting of 4 single batteries is used as a basic unit for inter-pack equalizing control, an intra-pack equalizing circuit is adopted in the battery pack to equalize the electric quantity, an inter-pack equalizing circuit and a flyback transformer are adopted between the battery pack and any other battery pack to realize the equalization and charging between every two battery packs, and the battery equalizing efficiency and flexibility are improved.
The technical scheme of the invention is a battery pack charging control method based on an improved Buck-Boost equalizing circuit, wherein the improved Buck-Boost equalizing circuit comprises n battery pairs, wherein the kth battery pair and k +1 battery pairs form an internal equalizing circuit, k =1,2 \8230, and n-1, n is more than or equal to 2; the group equalization circuit comprises a kth battery pair, namely a battery B connected in series 2k-1 、B 2k And the (k + 1) th cell pair, i.e. the cells B connected in series 2k+1 、B 2k+2 And a switching tube S 2k-1 、S 2k 、S 2k+1 、S 2k+2 And an inductance L k，1 、L k+1，1 Inductance L k,1 And battery B 2k-1 Is connected with the negative pole of the switch tube S, and the other end of the switch tube S is respectively connected with the negative pole of the switch tube S 2k-1 Source electrode and switch tube S 2k Is connected to the drain of the switching tube S 2k-1 Drain electrode of and battery B 2k-1 Is connected with the positive pole of the switching tube S 2k Source electrode of and battery B 2k Is connected with the negative pole of the anode; inductor L k+1,1 And battery B 2k+1 Is connected with the other end of the switch tube S 2k+1 Source electrode and switch tube S 2k+2 Is connected with the drain of the switch tube S 2k+1 Drain electrode of and battery B 2k+1 Is connected with the positive pole of the switching tube S 2k+2 Source electrode of (1) and battery B 2k+2 Is connected to the negative electrode of (1).
Battery B 2k-1 And a switch tube M for balancing the electric quantity of the battery k,2 Drain electrode connection of, cell B 2k+2 And a switch tube M for balancing the electric quantity of the battery k+1,1 Source connection of, inductor L k,2 One end of each of which is connected with the battery B 2k Negative electrode of (1), and battery B 2k+1 Positive electrode of (2) is connected with an inductor L k,2 The other end of the switch tube M is respectively connected with the switch tube M k,2 Source electrode and switch tube M k+1,1 Is connected to the drain of (1).
Furthermore, each switching tube is connected with a freewheeling diode in an anti-parallel mode;
when k is more than or equal to 2, the method is used for the battery to chargeBalanced switch tube M k,1 Drain of and switch tube M k-1,2 Is connected via an inductor L k-1,2 And battery B 2k-2 Is connected to the negative electrode of (1).
The kth battery pair can be subjected to intra-group power balance with the (k + 1) th battery pair or the (k-1) th battery pair according to the power balance requirement.
Further, the in-pack power equalization is performed by taking an in-pack equalization circuit formed by the batteries B1, B2, B3, and B4 as an example, and setting the power SOC of the single battery without loss of generality B1 >SOC B2 >SOC B3 >SOC B4 。
Firstly, the electric quantity of the batteries B1 and B2 is equalized, the electric quantity equalization of the batteries B1 and B2 comprises a discharging stage of the battery B1 and a charging stage of the battery B2,
battery B1 discharge phase: when t = t 0 The switching tube S is controlled by PWM signal 1 Is conducted through the battery B1 and the switch tube S 1 And an inductance L 1,1 A loop is formed to transfer the electric energy in the battery B1 to the inductor L 1,1 C, removing;
b2, charging stage: when t = t 1 Time, switch tube S 1 Turn off, at this time, the inductance L 1,1 Through battery B2 and switch tube S 2 The antiparallel freewheeling diode is conducted to form a loop, inductor L 1,1 The electric energy stored in the discharging stage of the battery B1 is released to the battery B2, and the battery B2 is charged.
The charge balance of the batteries B3, B4 is similar to the charge balance of the batteries B1, B2.
Then, the battery pair formed by the batteries B1 and B2 and the battery pair formed by the batteries B3 and B4 are respectively regarded as a unit, and the power balance is performed between the batteries B1 and B2 and the batteries B3 and B4, and the power balance of the adjacent battery pairs is similar to the power balance of the batteries B1 and B2.
Preferably, the improved Buck-Boost equalization circuit further comprises an inter-group equalization circuit, wherein the inter-group equalization circuit comprises switching tubes Q1 and Q2, an inductor L and a plurality of one-out-of-multiple switches; the improved Buck-Boost equalizing circuit takes a battery pack formed by adjacent battery pairs, namely 4 adjacent batteries, as a basic unit for equalizing the electric quantity between the groups, andthe other battery packs perform the electricity quantity equalization between the groups, taking the electricity quantity equalization between the kth and the k +1 th battery pairs and between the n-1 th and the n-th battery pairs as an example, the drain electrode of the switch tube Q1 for the electricity quantity equalization between the groups passes through the switch and the battery B of the kth battery pair 2k+1 The source electrode of the switching tube Q2 for the balance of the electricity quantity between the groups is connected with the battery B of the nth battery pair through the switch 2n Is connected with the negative pole of the anode; inductor L for electric quantity equalization among groups BG One end of the inductor is connected with the source electrode of the switching tube Q1 and the drain electrode of the switching tube Q2, and the inductor L BG The other end of the switch tube is respectively connected with the switch tube M through the switch k+1,1 Source electrode and switch tube M n-1,1 Is connected with the drain electrode of the transistor;
preferably, the improved Buck-Boost equalizing circuit further comprises an external charging circuit, wherein the external charging circuit comprises a transformer T, a switching tube Q3, an electrolytic capacitor C and a diode D; the dotted terminal H of the primary winding of the transformer T is connected with the anode of an external direct-current power supply, the other end of the primary winding of the transformer T is connected with the drain electrode of a switching tube Q3, and the source electrode of the switching tube Q3 is connected with the cathode of the external direct-current power supply; the switching tube Q3 is connected with a freewheeling diode in an anti-parallel mode; the dotted terminal H' of the secondary winding of the transformer T is connected with the negative electrode of the electrolytic capacitor C; the other end of the secondary winding of the transformer T is connected with the anode of a diode D, and the cathode of the diode D is connected with the anode of an electrolytic capacitor C; the negative electrode of the electrolytic capacitor C is used as the negative electrode of the external charging circuit, and the positive electrode of the electrolytic capacitor C is used as the positive electrode of the external charging circuit.
Preferably, the transformer T is a flyback transformer.
The electric quantity among the groups is balanced, and the specific process comprises the following steps:
1) Selecting and determining battery packs for balancing the electric quantity among the battery packs, and setting the selected battery packs to be balanced as a p-th battery pack and a q-th battery pack;
2) Respectively controlling a switch for selecting one more, and respectively connecting the p-th battery pack and the q-th battery pack with the inter-group equalizing circuit and the external charging circuit;
2.1 Control the one-out-of-many switch to make the drain electrode of the switch tube Q1 used for the electricity quantity balance between the groups connected with the positive electrode of the first battery of the p-th battery pack;
2.2 Control the one-out-of-multiple switch to make the source of the switch tube Q2 for the electricity balance between the groups connected with the negative pole of the fourth battery of the Q-th battery pack;
2.3 Control the one-out-of-multiple switch to make one end of the inductor L, which is used for the electricity quantity balance among the groups, far away from the switch tube Q1 respectively connected with the negative electrode of the fourth battery of the p-th battery pack and the positive electrode of the first battery of the Q-th battery pack;
2.4 Control a one-out-of-multiple switch to connect the positive electrode of the first battery of the p-th battery pack with the positive electrode of the external charging circuit;
2.5 Control a one-out-of-multiple switch to connect the negative electrode of the fourth battery of the qth battery pack with the negative electrode of the external charging circuit;
3) Controlling the switching tubes Q1 and Q2, and carrying out electric quantity equalization on the p-th battery pack and the Q-th battery pack by using the inductor L;
4) And controlling a switch tube Q3, and charging the p-th battery pack and the Q-th battery pack by different programs by using an external direct-current power supply and a transformer T until the p-th battery pack and the Q-th battery pack are fully charged.
The battery pack charging control method based on the improved Buck-Boost equalizing circuit comprises the following steps:
step 1: collecting the current and voltage of the single battery in real time;
step 2: estimating the SOC values of each single battery and the battery pack according to the acquired current and voltage;
and step 3: calculating the SOC average value epsilon of the battery pack and the electric quantity difference delta SOC between adjacent single batteries in the battery pack;
and 4, step 4: judging whether the epsilon is more than or equal to gamma, wherein the gamma represents an electric quantity threshold value;
step 4.1: if the epsilon is more than or equal to gamma, performing group equalization on the batteries in the battery pack, and executing the step 2;
and 4.2: if the epsilon is not more than or equal to the gamma, executing the step 5;
and 5: sampling the SOC value of each battery pack;
step 6: comparing the SOC values of the battery packs and sequencing;
and 7: determining the sequence of the balance among the battery pack groups according to the sequencing in the step 6;
the sequence of the balance among the battery pack groups is determined, the battery pack with the maximum SOC value and the battery pack with the minimum SOC value are taken out from the battery pack list to be balanced among the battery packs in sequence, and the balance among the battery packs is carried out for improving the efficiency and effect of electric quantity balance;
and 8: connecting the inter-group equalizing circuit and an external charging circuit for equalizing and charging;
and step 9: judging whether the electric quantity of the battery pack is full, and if so, ending; otherwise, step 8 is performed.
Compared with the prior art, the invention has the beneficial effects that:
1) The battery pack composed of 4 single batteries is used as a basic unit for the inter-group balance control, an intra-group balancing circuit is adopted in the battery pack for electric quantity balancing, an inter-group balancing circuit and a flyback transformer are adopted between the battery pack and other battery packs to realize the balance and charging between every two battery packs, the electric quantity balancing between any two battery packs is realized, the flexibility of the electric quantity balancing of the battery pack is improved, the battery balancing efficiency is improved, unnecessary middle batteries are prevented from participating in the electric quantity balancing process, the loss of a switching tube and the loss of electric energy are reduced, and the battery balancing time and the battery charging time are reduced;
2) The invention realizes the concurrent control of the inter-group balance and the battery pack charging, and improves the charging and balancing efficiency of the battery pack;
3) The invention realizes the balance and charging between the groups by pairing the battery pack with high electric quantity and the battery pack with low electric quantity, and further improves the electric quantity balance and charging efficiency.
Drawings
The invention is further illustrated by the following figures and examples.
Fig. 1 is a circuit diagram of an improved Buck-Boost equalization circuit according to an embodiment of the present invention.
Fig. 2 is a circuit diagram of an improved Buck-Boost equalization circuit including 8 batteries according to an embodiment of the present invention.
Fig. 3 is a schematic diagram illustrating a circuit simulation for performing inter-group equalization on battery packs p and q according to an embodiment of the present invention.
Fig. 4 is a diagram of an intra-pack balancing circuit including 4 batteries according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of inductive current waveforms for equalizing electric quantities of the batteries B1 and B2 according to the embodiment of the present invention.
Fig. 6 is a flowchart of a battery pack charging control method according to an embodiment of the present invention.
Detailed Description
As shown in FIG. 1, the improved Buck-Boost equalization circuit comprises n battery pairs, wherein the kth battery pair and k +1 battery pairs form an intra-group equalization circuit, k =1,2 \8230, and n-1, n is more than or equal to 2; the group equalization circuit comprises a kth battery pair, namely a battery B connected in series 2k-1 、B 2k And the (k + 1) th cell pair, i.e. the cells B connected in series 2k+1 、B 2k+2 And a switching tube S 2k-1 、S 2k 、S 2k+1 、S 2k+2 And an inductance L k,1 、L k+1,1 Inductance L k,1 And battery B 2k-1 Is connected with the negative pole of the switch tube S, and the other end of the switch tube S is respectively connected with the negative pole of the switch tube S 2k-1 Source electrode and switch tube S 2k Is connected with the drain of the switch tube S 2k-1 Drain electrode of and battery B 2k-1 Is connected with the positive pole of the switch tube S 2k Source electrode of (1) and battery B 2k The negative electrode of (1) is connected; inductor L k+1,1 And battery B 2k+1 Is connected with the other end of the switch tube S 2k+1 Source electrode and switch tube S 2k+2 Is connected to the drain of the switching tube S 2k+1 Drain electrode of and battery B 2k+1 Is connected with the positive pole of the switch tube S 2k+2 Source electrode of and battery B 2k+2 The negative electrode of (1) is connected; battery B 2k-1 And a switch tube M for balancing the electric quantity of the battery k,2 Drain electrode connection of, cell B 2k+2 And a switch tube M for balancing the electric quantity of the battery k+1,1 Source connection of, inductor L k,2 One end of each of which is connected with the battery B 2k Negative electrode of (1), and battery B 2k+1 Is connected to the positive pole of the inductor L k,2 The other end of the switch tube M is respectively connected with the switch tube M k,2 Source electrode and switch tube M k+1,1 Is connected with the drain electrode of the transistor; each switch tube is connected with a freewheeling diode in an anti-parallel mode.
As shown in fig. 2 and fig. 3, the improved Buck-Boost equalization circuit further includes an inter-group equalization circuit and an external charging circuit, wherein the inter-group equalization circuit includes switching tubes Q1 and Q2, an inductor L and a plurality of one-out-of-multiple switches; the external charging circuit comprises a transformer T, a switching tube Q3, an electrolytic capacitor C and a diode D.
The improved Buck-Boost equalization circuit takes a battery pack formed by adjacent battery pairs, namely 4 adjacent batteries, as a basic unit for inter-group electric quantity equalization, performs inter-group electric quantity equalization with other battery packs, takes inter-group electric quantity equalization between the kth and k +1 battery pairs and the (n-1) th and n battery pairs as an example, and uses the drain electrode of a switching tube Q1 for inter-group electric quantity equalization to pass through a switch and a battery B of the kth battery pair 2k+1 The source electrode of the switching tube Q2 for the balance of the electricity quantity between the groups is connected with the battery B of the nth battery pair through the switch 2n Is connected with the negative pole of the anode; inductor L for electric quantity equalization among groups BG One end of the inductor is connected with the source electrode of the switching tube Q1 and the drain electrode of the switching tube Q2, and the inductor L BG The other end of the switch is respectively connected with a switch tube M through a switch k+1,1 Source electrode and switch tube M n-1,1 Is connected to the drain of (c).
The dotted end of the primary winding of the transformer T is connected with the anode of an external direct-current power supply, the other end of the primary winding of the transformer T is connected with the drain electrode of a switching tube Q3, and the source electrode of the switching tube Q3 is connected with the cathode of the external direct-current power supply; the switching tube Q3 is connected with a freewheeling diode in an anti-parallel mode; the dotted end of the secondary winding of the transformer T is connected with the negative electrode of the electrolytic capacitor C; the other end of the secondary winding of the transformer T is connected with the anode of a diode D, and the cathode of the diode D is connected with the anode of an electrolytic capacitor C; the negative pole of the electrolytic capacitor C is connected with the switch tube M through the switch n,1 Is connected with the source electrode of the electrolytic capacitor C, the anode of the electrolytic capacitor C and the switch tube M k,2 Is connected to the drain of (1).
In an embodiment, the transformer T is a flyback transformer.
In one embodiment, the improved Buck-Boost equalization circuit comprises 8 single batteries, as shown in FIG. 2.
When k is more than or equal to 2, the switch tube M is used for balancing electric quantity of the battery k,1 Drain of (2) and switch tube M k-1,2 Is connected to the source of the first transistor,and via an inductor L k-1,2 And battery B 2k-2 Is connected with the negative pole of the anode;
the kth battery pair can be subjected to intra-group power equalization with the (k + 1) th battery pair or the (k-1) th battery pair according to the power equalization requirement.
Taking the intra-group equalization circuit composed of the batteries B1, B2, B3, and B4 as an example, as shown in fig. 4, the electric quantity SOC of the battery cell is set without loss of generality B1 ＞SOC B2 ＞SOC B3 ＞SOC B4 ，
Firstly, the batteries B1 and B2 are equalized, the equalization of the batteries B1 and B2 comprises a discharging stage of the battery B1 and a charging stage of the battery B2,
battery B1 discharge phase: when t = t 0 At the same time, the switch tube S1 is controlled to be conducted through the PWM signal, and the electric energy in the battery B1 is transferred to the inductor L through the loop (1) 1，1 In the above, without considering the internal resistance, the following equation holds:
wherein t is 0 Representing the inductance L 1，1 Starting charging time;
representing the inductance L 1，1 The voltage of (a) is set to be,
which represents the voltage of the battery B1,
representing the inductance L 1，1 The current of (a);
due to the fact that
Is a constant number of times, and is,so that the current of the inductor
Linear increase from 0, when t = t 1 When the inductance current reaches the maximum value
t 1 Representing the inductance L 1，1 The end of charging time;
in the formula T on Indicating switch tube S 1 On-time of (d); t is a unit of s Represents the switching period of the switching tube S1; d represents the conduction duty ratio of the switching tube S1;
battery B2 charging phase: when t = t 1 When the switch tube S1 is turned off, the inductor L is turned off 1，1 The battery B2 and the freewheeling diode connected with the switch tube S2 in inverse parallel are conducted to form a loop (2), and the inductor L 1，1 The electric energy stored in the discharging stage of the battery B1 is released to the battery B2, and the battery B2 is charged, and the following steps are performed:
in the formula t 2 Representing the inductance L 1，1 The discharge end time;
so that the inductor current decreases linearly from a maximum value when t = t 2 At this time, the inductor current is decreased to 0, and at this time, one cycle is ended, and the waveform is as shown in fig. 5;
the electric quantity balance of the batteries B3 and B4 is similar to that of the batteries B1 and B2;
then, the battery pair formed by the batteries B1 and B2 and the battery pair formed by the batteries B3 and B4 are respectively regarded as a unit, and the power balance is performed between the batteries B1 and B2 and the batteries B3 and B4, and the power balance of the adjacent battery pairs is similar to the power balance of the batteries B1 and B2.
The improved Buck-Boost equalization circuit also equalizes the electric quantity among the groups, and the specific process comprises the following steps:
1) Selecting and determining a battery pack for inter-group power balance, and setting the selected battery pack to be subjected to inter-group power balance as a p-th battery pack and a q-th battery pack;
2) Respectively controlling a multi-selection switch to connect the p-th battery pack and the q-th battery pack with the inter-group equalizing circuit and the external charging circuit;
2.1 Control the one-out-of-many switch to make the drain electrode of the switch tube Q1 used for the electricity quantity balance between the groups connected with the positive electrode of the first battery of the p-th battery pack;
2.2 Control the one-out-of-multiple switch to make the source of the switch tube Q2 for the electricity balance between the groups connected with the negative pole of the fourth battery of the Q-th battery pack;
2.3 Control the one-out-of-multiple switch to make one end of the inductor L, which is used for the electricity quantity balance among the groups, far away from the switch tube Q1 respectively connected with the negative electrode of the fourth battery of the p-th battery pack and the positive electrode of the first battery of the Q-th battery pack;
2.4 Control a one-out-of-many switch to connect the positive electrode of the first battery of the p-th battery pack with the positive electrode of the external charging circuit;
2.5 Control a one-out-of-multiple switch to connect a negative electrode of a fourth battery of the qth battery pack with a negative electrode of an external charging circuit;
3) Controlling the switching tubes Q1 and Q2, and carrying out electric quantity equalization on the p-th battery pack and the Q-th battery pack by using the inductor L;
4) And controlling a switching tube Q3, and charging the p-th battery pack and the Q-th battery pack by different programs by using an external direct-current power supply and a transformer T until the p-th battery pack and the Q-th battery pack are fully charged.
As shown in fig. 6, the method for controlling battery pack charging based on the improved Buck-Boost equalization circuit includes the following steps:
step 1: collecting the current and voltage of the single battery in real time;
and 2, step: estimating the SOC values of each single battery and the battery pack according to the acquired current and voltage;
and step 3: calculating the SOC average value epsilon of the battery pack and the electric quantity difference delta SOC between adjacent single batteries in the battery pack;
and 4, step 4: judging whether the electric quantity is greater than or equal to a threshold value, wherein the threshold value represents the electric quantity;
step 4.1: if the current battery pack is not less than the preset value, performing group equalization on the batteries in the battery pack, and executing the step 2;
step 4.2: if not, executing the step 5;
and 5: sampling the SOC value of each battery pack;
and 6: comparing the SOC values of the battery packs and sequencing;
and 7: determining the sequence of the balance among the battery pack groups according to the sequence of the step 6;
and 8: connecting the inter-group equalizing circuit and an external charging circuit for equalizing and charging;
and step 9: judging whether the electric quantity of the battery pack is full, and if so, ending; otherwise, step 8 is performed.
Claims (8)
1. The battery pack charging control method based on the improved Buck-Boost equalizing circuit is characterized in that the improved Buck-Boost equalizing circuit comprises n battery pairs, wherein the kth battery pair and k +1 battery pairs form an internal equalizing circuit, k =1,2 \8230, and n-1, n is more than or equal to 2; the group equalization circuit comprises a kth battery pair, namely a battery B connected in series 2k-1 、B 2k And the (k + 1) th cell pair, i.e. the cells B connected in series 2k+1 、B 2k+2 And a switching tube S 2k-1 、S 2k 、S 2k+1 、S 2k+2 And an inductance L k,1 、L k+1,1 Inductance L k,1 And battery B 2k-1 Is connected with the negative pole of the switch tube S, and the other end of the switch tube S is respectively connected with the negative pole of the switch tube S 2k-1 Source electrode and switch tube S 2k Is connected to the drain of the switching tube S 2k-1 Drain electrode of (1) and battery B 2k-1 Is connected with the positive pole of the switch tube S 2k Source electrode of (1) and battery B 2k The negative electrode of (1) is connected;
inductor L k+1,1 And battery B 2k+1 Is connected with the other end of the switch tube S 2k+1 Source electrode and switch tube S 2k+2 Is connected to the drain of the switching tube S 2k+1 Drain electrode of and battery B 2k+1 Is connected with the positive pole of the switch tube S 2k+2 Source electrode of and battery B 2k+2 The negative electrode of (1) is connected;
battery B 2k-1 The positive electrode of (2) and the switch tube M k,2 Drain electrode connection of, cell B 2k+2 And a switch tube M k+1,1 Source connection of (2), inductance L k,2 One end of each of which is connected with the battery B 2k Negative electrode of (1), and battery B 2k+1 Positive electrode of (2) is connected with an inductor L k,2 The other end of the switch tube M is respectively connected with the switch tube M k,2 Source electrode and switch tube M k+1,1 Is connected with the drain electrode of the transistor;
when k is greater than or equal to 2, the switch tube M k,1 Drain of and switch tube M k-1,2 Is connected via an inductor L k-1,2 And battery B 2k-2 The negative electrode of (1) is connected;
each switching tube is connected with a freewheeling diode in an anti-parallel mode;
the kth battery pair can be subjected to intra-group power balance with the (k + 1) th battery pair or the (k-1) th battery pair according to the power balance requirement.
2. The battery pack charge control method according to claim 1, wherein the intra-pack charge equalization is performed by using an intra-pack equalization circuit formed of batteries B1, B2, B3, and B4 as an example, and the charge SOC of the battery cells is set without loss of generality B1 >SOC B2 >SOC B3 >SOC B4 In which SOC is B1 、SOC B2 、SOC B3 、SOC B4 The electric quantities of the batteries B1, B2, B3 and B4 respectively;
firstly, the electric quantity of the batteries B1 and B2 is equalized, the electric quantity equalization of the batteries B1 and B2 comprises a discharging stage of the battery B1 and a charging stage of the battery B2,
battery B1 discharge phase: when t = t 0 The switching tube S is controlled by PWM signal 1 Is conducted through the battery B1 and the switch tube S 1 And an inductance L 1,1 A circuit is formed to convert the electric energy in the battery B1To the inductor L 1,1 In the above, without considering the internal resistance, the following equation holds:
wherein t is 0 Representing the inductance L 1,1 Starting charging time;
representing the inductance L 1,1 The voltage of (a) is set to be,
which represents the voltage of the battery B1,
representing the inductance L 1,1 The current of (a);
due to the fact that
Is constant, so that the current of the inductor is constant
Linear increase from 0, when t = t 1 When the inductor current reaches the maximum value
t 1 Representing inductance L 1,1 The end of charging time;
in the formula T on To representSwitch tube S 1 On-time of (d); t is S Represents the switching period of the switching tube S1; d represents the conducting duty ratio of the switching tube S1;
battery B2 charging phase: when t = t 1 Time, switch tube S 1 Turn off, at this time, the inductance L 1,1 Through battery B2 and switch tube S 2 The antiparallel freewheeling diode is conducted to form a loop, inductor L 1,1 The electric energy stored in the discharging stage of the battery B1 is released to the battery B2, and the battery B2 is charged, and the following steps are carried out:
in the formula t 2 Representing the inductance L 1,1 The discharge end time;
represents the voltage of battery B2;
the inductor current is linearly reduced from the maximum value at the moment when t = t 2 When the inductive current is reduced to 0, a balanced period between the batteries B1 and B2 is finished;
the electric quantity balance of the batteries B3 and B4 is similar to that of the batteries B1 and B2;
then, the battery pair formed by the batteries B1 and B2 and the battery pair formed by the batteries B3 and B4 are respectively regarded as a unit, and the power balance is performed between the batteries B1 and B2 and the batteries B3 and B4, and the power balance of the adjacent battery pairs is similar to the power balance of the batteries B1 and B2.
3. The battery pack charging control method according to claim 2, wherein the improved Buck-Boost equalization circuit further comprises an inter-group equalization circuit, the inter-group equalization circuit comprising switching tubes Q1, Q2 and an inductor L, and a plurality of one-out-of-multiple switches;
the improved Buck-Boost equalization circuit takes a battery pack formed by adjacent battery pairs, namely 4 adjacent batteries, as a basic unit for inter-group power equalization, performs inter-group power equalization with other battery packs, takes the inter-group power equalization between the kth and k +1 battery pairs and the (n-1) th and n battery pairs as an example, and uses the drain electrode of a switching tube Q1 for the inter-group power equalization to be switched with a battery B of the kth battery pair 2k+1 The source electrode of the switch tube Q2 used for the inter-group electric quantity equalization is connected with the battery B of the nth battery pair through the switch 2n Is connected with the negative pole of the anode; inductor L for equalizing electric quantity among groups BG One end of the inductor is connected with the source electrode of the switching tube Q1 and the drain electrode of the switching tube Q2, and the inductor L BG The other end of the switch is respectively connected with a switch tube M through a switch k+1,1 Source electrode and switch tube M n-1,1 Is connected to the drain of (1).
4. The battery pack charge control method according to claim 3, wherein the modified Buck-Boost equalizing circuit further comprises an external charging circuit including a transformer T, a switching tube Q3, an electrolytic capacitor C, and a diode D;
the dotted end of the primary winding of the transformer T is connected with the anode of an external direct-current power supply, the other end of the primary winding of the transformer T is connected with the drain electrode of a switching tube Q3, and the source electrode of the switching tube Q3 is connected with the cathode of the external direct-current power supply; the switching tube Q3 is connected with a freewheeling diode in an anti-parallel mode; the dotted end of the secondary winding of the transformer T is connected with the negative electrode of the electrolytic capacitor C; the other end of the secondary winding of the transformer T is connected with the anode of a diode D, and the cathode of the diode D is connected with the anode of an electrolytic capacitor C; the negative electrode of the electrolytic capacitor C is used as the negative electrode of the external charging circuit, and the positive electrode of the electrolytic capacitor C is used as the positive electrode of the external charging circuit.
5. The battery pack charging control method according to claim 4, wherein the transformer T is a flyback transformer.
6. The method of claim 5, wherein the balancing of the inter-group charge comprises:
1) Selecting and determining battery packs for balancing the electric quantity among the battery packs, and setting the selected battery packs to be balanced as a p-th battery pack and a q-th battery pack;
2) Respectively controlling a multi-selection switch to connect the p-th battery pack and the q-th battery pack with the inter-group equalizing circuit and the external charging circuit;
2.1 Control the one-out-of-many switch to make the drain electrode of the switch tube Q1 used for the electricity quantity balance between the groups connected with the positive electrode of the first battery of the p-th battery pack;
2.2 Control a one-out-of-multiple switch to enable a source electrode of a switch tube Q2 used for electricity quantity balance among the groups to be connected with a negative electrode of a fourth battery of the qth battery pack;
2.3 Control a one-out-of-multiple switch to enable one end of an inductor L used for inter-group electric quantity equalization, which is far away from a switch tube Q1, to be respectively connected with a negative electrode of a fourth battery of a p-th battery pack and a positive electrode of a first battery of the Q-th battery pack;
2.4 Control a one-out-of-multiple switch to connect the positive electrode of the first battery of the p-th battery pack with the positive electrode of the external charging circuit;
2.5 Control a one-out-of-multiple switch to connect a negative electrode of a fourth battery of the qth battery pack with a negative electrode of an external charging circuit;
3) Controlling the switching tubes Q1 and Q2, and carrying out electric quantity equalization on the p-th battery pack and the Q-th battery pack by using the inductor L;
4) And controlling a switching tube Q3, and charging the p-th battery pack and the Q-th battery pack by different programs by using an external direct-current power supply and a transformer T until the p-th battery pack and the Q-th battery pack are fully charged.
7. The battery pack charge control method according to claim 6, characterized by comprising the steps of:
step 1: collecting the current and voltage of the single battery in real time;
step 2: estimating the SOC values of each single battery and the battery pack according to the acquired current and voltage;
and step 3: calculating the SOC average value epsilon of the battery pack and the electric quantity difference delta SOC between adjacent single batteries in the battery pack;
and 4, step 4: judging whether the epsilon is more than or equal to gamma, wherein the gamma represents an electric quantity threshold value;
step 4.1: if the epsilon is more than or equal to gamma, performing group equalization on the batteries in the battery pack, and executing the step 2;
step 4.2: if the epsilon is not more than or equal to the gamma, executing the step 5;
and 5: sampling the SOC value of each battery pack;
step 6: comparing the SOC values of the battery packs and sequencing;
and 7: determining the sequence of the balance among the battery pack groups according to the sequence of the step 6;
and 8: connecting the inter-group equalizing circuit and an external charging circuit for equalizing and charging;
and step 9: judging whether the electric quantity of the battery pack is full, and if so, ending the process; otherwise, step 8 is performed.
8. The battery pack charging control method according to claim 7, wherein in step 7, the sequence of the balancing among the battery pack groups is determined, and the battery pack with the largest SOC value and the battery pack with the smallest SOC value are sequentially taken out from the battery pack list to be balanced among the battery packs to perform the balancing among the battery packs, so as to improve the efficiency and effect of the electric quantity balancing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211519544.XA CN115800449A (en) | 2022-11-30 | 2022-11-30 | Battery pack charging control method based on improved Buck-Boost equalization circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211519544.XA CN115800449A (en) | 2022-11-30 | 2022-11-30 | Battery pack charging control method based on improved Buck-Boost equalization circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115800449A true CN115800449A (en) | 2023-03-14 |
Family
ID=85443673
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211519544.XA Pending CN115800449A (en) | 2022-11-30 | 2022-11-30 | Battery pack charging control method based on improved Buck-Boost equalization circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115800449A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116154924A (en) * | 2023-04-14 | 2023-05-23 | 苏州大学 | Active equalization system and method for lithium battery based on double-layer topology |
-
2022
- 2022-11-30 CN CN202211519544.XA patent/CN115800449A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116154924A (en) * | 2023-04-14 | 2023-05-23 | 苏州大学 | Active equalization system and method for lithium battery based on double-layer topology |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106712191B (en) | Battery pack equalization circuit and method based on external energy storage unit and LC quasi-resonance | |
| CN106712211B (en) | Double-layer active equalization circuit based on multi-input transformation and implementation method | |
| CN104578288B (en) | A kind of efficient balanced device topological circuit of double-deck bridge arm series-connected batteries and its control method | |
| CN107134599B (en) | Voltage equalization circuit of series battery pack and working method thereof | |
| CN210123897U (en) | Battery equalization circuit | |
| CN112202218B (en) | Equalizing circuit based on bipolar T-shaped double-resonance switch capacitor converter and control method | |
| Moghaddam et al. | A battery equalization technique based on Ćuk converter balancing for lithium ion batteries | |
| Chen et al. | An any-cell (s)-to-cell (s) equalization method with a single magnetic component for Lithium-ion battery pack | |
| CN109066846B (en) | Modular inter-battery equalization circuit structure and method | |
| WO2023179732A1 (en) | Parallel battery cluster topology integrated with circulating current suppression and state-of-charge equalization circuit | |
| CN103023107A (en) | Novel lithium battery pack lossless equalization circuit | |
| Qi et al. | Optimization of centralized equalization systems based on an integrated cascade bidirectional DC–DC converter | |
| CN104868532A (en) | Cuk chopper circuit bidirectional arm-based series storage cell pack bidirectional energy equalizer and control method thereof | |
| CN203104011U (en) | Charge/discharge managing and equalizing system for storage battery or capacitor | |
| CN111555407A (en) | Series-parallel battery pack integrated active equalization method based on inductive energy storage | |
| CN115800449A (en) | Battery pack charging control method based on improved Buck-Boost equalization circuit | |
| CN110649337A (en) | Novel lithium ion battery Cell-to-Cell modular equalization circuit based on single inductor and control method | |
| CN113162159B (en) | Improved Cell-to-Cell battery equalization circuit based on LC resonance circuit and implementation method | |
| CN112234674B (en) | In-cluster equalization circuit and equalization control method | |
| CN110707780B (en) | Staggered battery equalization circuit structure based on transformer | |
| CN210607522U (en) | Novel lithium ion battery Cell-to-Cell modularized equalization circuit based on single inductor | |
| CN218958586U (en) | Dual-mode active equalization lithium ion battery circuit | |
| CN204376462U (en) | The efficient equalizer topological circuit of a kind of double-deck brachium pontis series-connected batteries | |
| CN210912093U (en) | Equalizing circuit based on switched capacitor and LC resonance unit | |
| Dai et al. | Analysis, design and implementation of flexible interlaced converter for lithium battery active balancing in electric vehicles |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |