CN117748629A - Multi-parallel-serial battery equalization circuit and method - Google Patents
Multi-parallel-serial battery equalization circuit and method Download PDFInfo
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- CN117748629A CN117748629A CN202211119747.XA CN202211119747A CN117748629A CN 117748629 A CN117748629 A CN 117748629A CN 202211119747 A CN202211119747 A CN 202211119747A CN 117748629 A CN117748629 A CN 117748629A
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Abstract
The invention provides a multi-parallel-serial battery equalization circuit and an equalization method, wherein the equalization circuit comprises: a plurality of battery cells connected in series; the equalization discharging circuit is respectively connected with the positive electrode and the negative electrode of the battery cell and is used for charging and discharging the battery cell; the current sampling resistor is used for limiting the current in the battery cell serial loop; the sampling unit is used for collecting electric signal data of the battery cells in the equalization control process; and the micro-control unit is used for carrying out balanced management on the battery cells according to the electric signal data acquired by the sampling unit. The equalization circuit and the equalization method are relatively simple in implementation mode, and can enable the equalized average current to be set in a higher range so as to improve the equalization efficiency of the multi-parallel-serial battery management system.
Description
Technical Field
The invention relates to the field of battery management, in particular to a multi-parallel-serial battery equalization circuit and a multi-parallel-serial battery equalization method.
Background
In a multi-parallel-serial battery management system, the equalization is usually realized by passive equalization, and an analog front-end chip with a fixed equalization duty ratio is mostly adopted, so that the average current for equalization can be limited to a certain range, the equalization efficiency is affected to a certain extent, and the best equalization effect cannot be provided.
In the multi-parallel-serial battery management system, when a certain voltage difference exists among battery cells connected in series, the multi-parallel-serial battery has unbalanced batteries. In order to solve the battery imbalance phenomenon, passive equalization is adopted in most practical applications.
During battery equalization, the cell voltage is not sampled. Therefore, in the case where both equalization and sampling are required, equalization can only be performed in the form of a switch, with cell voltage sampling alternating with equalization, with a duty cycle that is typically measured to measure the time of equalization, e.g., 75% duty cycle represents that 750ms is being equalized during a 1 second period, and the other 250ms is being cell voltage sampling is being performed, but not. The larger the duty cycle, the longer the equalization time, and the larger the average current to be equalized.
In the analog front end solution, the duty cycle is fixed. Therefore, the average current for equalization is also fixed. In order to improve the balanced average current, only an external balancing circuit can be used, but the balanced duty ratio of the external balancing circuit is still controlled by the analog front end, and the maximization of the balanced efficiency cannot be realized.
Disclosure of Invention
The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a multi-parallel-serial battery equalization circuit and method that overcomes or at least partially solves the above-mentioned problems.
According to an aspect of the present invention, there is provided a multi-parallel-serial battery equalization circuit including:
a plurality of battery cells connected in series;
the equalization discharging circuit is respectively connected with the positive electrode and the negative electrode of the battery cell and is used for equalizing discharge of the battery cell;
the current sampling resistor is used for limiting the current in the battery cell serial loop;
the sampling unit is used for collecting electric signal data of the battery cells in the equalization control process;
and the micro-control unit is used for carrying out balanced management on the battery cells according to the electric signal data acquired by the sampling unit.
Optionally, the sampling unit specifically includes: the battery cell temperature sampling unit, the current sampling unit and the voltage sampling unit;
the input end of the current sampling unit is connected with the current sampling resistor in parallel, and the output end of the current sampling unit is connected with the micro-control unit and is used for collecting current signals in the equalization control process and sending the current signals to the micro-control unit;
the battery cell temperature sampling unit is connected with the micro control unit and is used for collecting temperature signals in the battery cell equalization control process and sending the temperature signals to the micro control unit;
the input end of the voltage sampling unit is connected with the battery cell in parallel, and the output end of the voltage sampling unit is connected with the micro-control unit and is used for collecting voltage signals of the battery cell in the equalization control process and sending the voltage signals to the micro-control unit.
Optionally, the negative electrode of the last battery cell is connected with one end of the current sampling resistor and the ground wire respectively.
Optionally, the equalizing discharge circuit specifically includes: MOS drive, field effect transistor and balanced discharge resistor;
one end of the MOS drive is connected with the grid electrode of the field effect transistor;
the other end of the MOS drive is connected with the micro control unit;
the drain electrode of the field effect transistor is connected with one end of the balanced discharge resistor;
the other end of the balanced discharge resistor is connected with the positive electrode of the battery cell;
and the cathode of the battery cell is connected with the source electrode of the field effect transistor.
The invention also discloses a multi-parallel-serial battery balancing method, which comprises the following steps:
setting an initial value of an equilibrium duty ratio;
simultaneously, the sampling unit collects voltage signals of a plurality of battery monomers;
the micro control unit determines the voltage signal and judges that the battery cells need to be balanced, and performs balanced control according to the initial value of the balanced duty ratio;
the sampling unit acquires a temperature signal and a current signal of the battery cell in the equalization control process;
the micro control unit determines that the equalization efficiency needs to be improved, adjusts the equalization duty ratio to 100%, and calculates the voltage of the battery cell.
Optionally, the determining the voltage signal and determining that the battery cell needs to be balanced by the micro control unit specifically includes:
collecting voltage signals of a plurality of battery monomers;
obtaining a maximum voltage value and a minimum voltage value from the voltage signal;
if the maximum voltage value is in a non-flat region of the OCV curve of the battery;
and determining that the voltage difference between the voltage signal of the battery cell and the minimum voltage value of the battery cell is larger than an equalization threshold value, and starting charge equalization of the battery cell.
Optionally, the performing the equalization control according to the initial value of the equalization duty cycle specifically includes:
determining a battery monomer channel which needs to be balanced currently according to an equalization algorithm;
and controlling the switch of the battery cell channel according to the initial value of the balanced duty ratio.
Optionally, the adjusting the balanced duty cycle to be 100% and calculating the voltage of the battery cell specifically includes:
adjusting the balance duty ratio to 100%;
calculating the depth of discharge DOD of the battery cell according to the temperature signal and the current signal;
searching a battery Open Circuit Voltage (OCV) -depth of discharge (DOD) table according to the depth of discharge (DOD) and the temperature to obtain the OCV;
obtaining impedance information R of the battery unit according to the battery open circuit voltage OCV and an impedance table;
and calculating the voltage of the current battery cell by adopting impedance compensation according to the impedance information R.
Optionally, the calculating the current voltage of the battery cell by adopting impedance compensation according to the impedance information R specifically includes:
voltage V of battery cell = battery open circuit voltage OCV-current signal I-impedance information R.
Optionally, the period of the signal collected by the sampling unit is set to 1 second.
The invention provides a multi-parallel-serial battery equalization circuit and an equalization method, wherein the equalization circuit comprises: a plurality of battery cells connected in series; the equalization discharging circuit is respectively connected with the positive electrode and the negative electrode of the battery cell and is used for charging and discharging the battery cell; the current sampling resistor is used for limiting the current in the battery cell serial loop; the sampling unit is used for collecting electric signal data of the battery cells in the equalization control process; and the micro-control unit is used for carrying out balanced management on the battery cells according to the electric signal data acquired by the sampling unit. The equalization circuit and the equalization method are relatively simple in implementation mode, and can enable the equalized average current to be set in a higher range so as to improve the equalization efficiency of the multi-parallel-serial battery management system.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present invention more readily apparent.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a multi-parallel-serial battery equalization circuit according to an embodiment of the present invention;
fig. 2 is a flowchart of a multi-parallel-serial battery balancing method according to an embodiment of the present invention;
fig. 3 is a flowchart of determining whether the battery cells need to be balanced according to the voltage signal according to the embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The terms "comprising" and "having" and any variations thereof in the description embodiments of the invention and in the claims and drawings are intended to cover a non-exclusive inclusion, such as a series of steps or elements.
The technical scheme of the invention is further described in detail below with reference to the accompanying drawings and the examples.
Example 1
As shown in fig. 1, a multi-parallel-serial battery equalization circuit includes: 4 equalization discharging circuits, 4 battery cells 4, 4 voltage sampling units 5, a micro control unit 6, a battery cell temperature sampling unit 7, a current sampling unit 8 and a current sampling resistor 9;
each equalization discharging circuit is respectively connected with the positive electrode and the negative electrode of the battery cell 4 to charge the battery cell 4;
the equalization discharging circuit specifically comprises: a MOS drive 1, a field effect transistor 2 and an equalizing discharge resistor 3; one end of the MOS driver 1 is connected with the grid electrode of the field effect transistor 2; the other end of the MOS drive 1 is connected with a micro control unit 6; the drain electrode of the field effect transistor 2 is connected with one end of the balanced discharge resistor 3; the other end of the balance discharge resistor 3 is connected with the anode of the battery cell 4; the negative electrode of the battery cell 4 is connected to the source of the field effect transistor 2.
The input end of the voltage sampling unit 7 is connected with the battery cell 4 in parallel, and the output end is connected with the micro control unit 6; the acquired voltage signal is sent to the micro control unit 6.
The 4 battery cells 4 are connected in series; the negative electrode of the last battery cell is respectively connected with one end of the current sampling resistor 9 and the ground wire.
The input end of the current sampling unit 8 is connected with the current sampling resistor 9 in parallel, and the output end is connected with the micro control unit 6; the acquired current signal is sent to the micro control unit 6.
The battery cell temperature sampling unit 7 is connected with the micro control unit 6, and sends the collected battery cell temperature signal to the micro control unit 6.
As shown in fig. 2, the present embodiment further provides a multi-parallel-serial battery equalization method, where the multi-parallel-serial battery equalization circuit is applied, and the equalization method includes:
step 100: setting an initial value of an equilibrium duty ratio to 75%;
step 200: collecting voltage signals of a plurality of battery monomers;
step 300: judging whether the battery monomers need to be balanced or not according to the voltage signals; if so, step 400: determining a battery monomer channel which needs to be balanced currently according to an equalization algorithm; controlling the switch of the battery monomer channel according to the initial value of the balanced duty ratio;
step 500: collecting the temperature and current of the battery monomer in the process of equalization control;
step 600: judging whether the equalization efficiency needs to be improved, if so, step 700: adjusting the balance duty ratio to 100%;
step 800: calculating the depth of discharge DOD of the battery cell according to the temperature and the current;
searching a battery open circuit voltage OCV-depth of discharge DOD table according to the depth of discharge DOD and the temperature to obtain a battery open circuit voltage OCV;
obtaining impedance information R of the battery unit according to the open-circuit voltage OCV of the battery and the impedance meter;
step 900: calculating the voltage of the current battery cell by adopting impedance compensation according to the impedance information R; otherwise, step 1000: continuously balancing according to 75% of the initial value of the balancing duty ratio;
otherwise, step 1100: stopping equalization;
and continuously and circularly collecting the voltage signals in the equalization process until the equalization is finished.
As shown in fig. 3, determining whether the battery cells need to be balanced according to the voltage signal specifically includes:
step S1: collecting voltage signals of a plurality of battery monomers;
step S2: obtaining a maximum voltage value and a minimum voltage value from the voltage signal;
step S3: if the maximum voltage value is in the non-flat region of the OCV curve of the battery;
step S4: judging whether the voltage difference between the voltage signal of the battery cell and the minimum voltage value of the battery cell is larger than an equilibrium threshold value or not; if yes, step S5: the battery monomers need to be balanced; otherwise, step S6: no equalization is required.
The starting judgment step of the charge balance is as follows:
obtaining the maximum voltage value and the minimum voltage value in a plurality of battery monomers;
whether the maximum voltage value is in the non-flat region of the OCV curve of the cell, e.g., the maximum voltage value is greater than 4000mV;
whether the voltage difference is greater than a set equalization threshold, such as 100mV; if the steps 2 and 3 are satisfied at the same time, charge equalization is started. The specific steps are as follows: the difference between the voltage of the battery cell and the minimum voltage value is greater than a set threshold, such as 10mV, and the battery cell is subjected to balanced discharge, i.e. the Mos of the corresponding channel is closed.
If it is found that the steps 2 and 3 are not satisfied simultaneously in the calculation of the cell voltage in the subsequent cycle (1 second cycle), the charge equalization is ended.
The beneficial effects are that: the voltage sampling process of each battery monomer can be replaced, so that the equalization efficiency of the battery monomer can be improved to 100%, and meanwhile, voltage signals of each battery monomer can be provided for the operation of a battery management system, and the normal operation of the system is ensured.
The equalization method and the circuit are relatively simple in implementation mode, and the equalization average current can be set in a higher range so as to improve the equalization efficiency of the multi-parallel-serial battery management system.
The foregoing detailed description of the invention has been presented for purposes of illustration and description, and it should be understood that the invention is not limited to the particular embodiments disclosed, but is intended to cover all modifications, equivalents, alternatives, and improvements within the spirit and principles of the invention.
Claims (10)
1. A multi-parallel-serial battery equalization circuit, the equalization circuit comprising:
a plurality of battery cells connected in series;
the equalization discharging circuit is respectively connected with the positive electrode and the negative electrode of the battery cell and is used for equalizing discharge of the battery cell;
the current sampling resistor is used for limiting the current in the battery cell serial loop;
the sampling unit is used for collecting electric signal data of the battery cells in the equalization control process;
and the micro-control unit is used for carrying out balanced management on the battery cells according to the electric signal data acquired by the sampling unit.
2. The multi-parallel-serial battery equalization circuit of claim 1, wherein said sampling unit specifically comprises: the battery cell temperature sampling unit, the current sampling unit and the voltage sampling unit;
the input end of the current sampling unit is connected with the current sampling resistor in parallel, and the output end of the current sampling unit is connected with the micro-control unit and is used for collecting current signals in the equalization control process and sending the current signals to the micro-control unit;
the battery cell temperature sampling unit is connected with the micro control unit and is used for collecting temperature signals in the battery cell equalization control process and sending the temperature signals to the micro control unit;
the input end of the voltage sampling unit is connected with the battery cell in parallel, and the output end of the voltage sampling unit is connected with the micro control unit and is used for collecting voltage signals of the battery cell in the equalization control process and transmitting the voltage signals to the micro control unit;
the micro control unit calculates the voltage of the battery cell according to the voltage signal.
3. The multi-parallel-serial battery equalization circuit of claim 1, wherein the negative electrode of the last battery cell is connected to one end of the current sampling resistor and a ground line, respectively.
4. The multi-parallel-serial battery equalization circuit of claim 1, wherein said equalization discharge circuit specifically comprises: MOS drive, field effect transistor and balanced discharge resistor;
one end of the MOS drive is connected with the grid electrode of the field effect transistor;
the other end of the MOS drive is connected with the micro control unit;
the drain electrode of the field effect transistor is connected with one end of the balanced discharge resistor;
the other end of the balanced discharge resistor is connected with the positive electrode of the battery cell;
the cathode of the battery monomer is connected with the source electrode of the field effect transistor;
and when the Mos drive is closed, the equalization discharge resistor performs passive equalization discharge on the battery cell.
5. A multi-parallel-serial battery equalization method, applying the multi-parallel-serial battery equalization circuit of any one of the above claims 1-4, characterized in that the equalization method comprises:
setting an initial value of an equilibrium duty ratio;
simultaneously, the sampling unit collects voltage signals of a plurality of battery monomers;
the micro control unit determines the voltage signal and judges that the battery cells need to be balanced, and performs balanced control according to the initial value of the balanced duty ratio;
the sampling unit acquires a temperature signal and a current signal of the battery cell in the equalization control process;
the micro control unit determines that the equalization efficiency needs to be improved, adjusts the equalization duty ratio to 100%, and calculates the voltage of the battery cell.
6. The method for balancing multiple parallel-serial batteries according to claim 5, wherein said determining the voltage signal and determining that the battery cells need to be balanced by the micro control unit comprises:
collecting voltage signals of a plurality of battery monomers;
obtaining a maximum voltage value and a minimum voltage value from the voltage signal;
if the maximum voltage value is in a non-flat region of the OCV curve of the battery;
and determining that the voltage difference between the voltage signal of the battery cell and the minimum voltage value of the battery cell is larger than an equalization threshold value, and starting charge equalization of the battery cell.
7. The method for equalizing a multiple parallel-serial battery according to claim 5, wherein said performing equalization control according to said initial value of the equalization duty ratio specifically comprises:
determining a battery monomer channel which needs to be balanced currently according to an equalization algorithm;
and controlling the switch of the battery cell channel according to the initial value of the balanced duty ratio.
8. The method for balancing multiple parallel-serial batteries according to claim 5, wherein said adjusting the balancing duty ratio to 100% and calculating the voltage of said battery cell comprises:
adjusting the balance duty ratio to 100%;
calculating the depth of discharge DOD of the battery cell according to the temperature signal and the current signal;
searching a battery Open Circuit Voltage (OCV) -depth of discharge (DOD) table according to the depth of discharge (DOD) and the temperature to obtain the OCV;
obtaining impedance information R of the battery unit according to the battery open circuit voltage OCV and an impedance table;
and calculating the voltage of the current battery cell by adopting impedance compensation according to the impedance information R.
9. The method for balancing multiple parallel-serial batteries according to claim 8, wherein said calculating the voltage of the current battery cell by using impedance compensation according to the impedance information R comprises:
voltage V of battery cell = battery open circuit voltage OCV-current signal I-impedance information R.
10. The multi-parallel-serial battery equalization method of claim 5, wherein a period of the sampling unit collecting signals is set to 1 second.
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| CN202211119747.XA CN117748629A (en) | 2022-09-15 | 2022-09-15 | Multi-parallel-serial battery equalization circuit and method |
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| CN202211119747.XA CN117748629A (en) | 2022-09-15 | 2022-09-15 | Multi-parallel-serial battery equalization circuit and method |
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| CN117748629A true CN117748629A (en) | 2024-03-22 |
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| CN202211119747.XA Pending CN117748629A (en) | 2022-09-15 | 2022-09-15 | Multi-parallel-serial battery equalization circuit and method |
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