A battery pack single cell voltage sampling and correction circuit and method

Abstract

The present invention discloses a voltage sampling and correction circuit for a battery pack single cell. The battery pack is provided with a plurality of battery groups connected in sequence. The battery group is provided with a plurality of single cells connected in sequence. The circuit includes an ADC sampling chip, a signal processing circuit, a control unit and a plurality of battery sampling chips. The single cells are electrically connected to the battery sampling chip. At least one of the single cells is electrically connected to the signal processing circuit. The signal processing circuit, the ADC sampling chip and the control unit are electrically connected in sequence. At least one of the battery sampling chips is electrically connected to the signal processing circuit. The plurality of battery sampling chips are electrically connected to the control unit respectively. The battery sampling chip and the ADC sampling chip simultaneously collect the voltage of the same single cell. The voltage collected by the ADC sampling chip is used as a voltage reference value. The voltage reference value is compared with the voltage measurement value collected by the battery sampling chip to obtain the sampling error of the battery sampling chip, so as to improve the sampling accuracy of the voltage sampling and correction circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of single cell voltage sampling, and in particular to a single cell voltage sampling and correction circuit and method for a battery pack. Background Art

[0002] At present, the voltage sampling of single cells in the battery management system is usually implemented by multiple integrated chips. Since the voltage error of the single cell collected by the integrated chip is large, and there are also errors between different integrated chips, the error will gradually accumulate when the integrated chip collects the voltage of dozens or even hundreds of single cells, resulting in poor voltage measurement accuracy, which cannot meet the application scenarios of remaining capacity (SOC), health status (SOH), battery balancing and other complex algorithms and high-precision requirements in the fields of automobiles and energy storage. The sampling accuracy of some industrial-grade sampling chips cannot meet the application requirements of iron-lithium batteries, and the cost of use is also high. Summary of the invention

[0003] The present invention provides a battery pack single cell voltage sampling and correction circuit and method to solve the problem of large voltage error of single cell voltages collected between integrated chips.

[0004] In order to solve the above technical defects, the technical solution adopted by the present invention is to provide a battery pack single cell voltage sampling and correction circuit, wherein the battery pack is provided with a plurality of battery groups connected in sequence, and the battery group is provided with a plurality of single cells connected in sequence, including an ADC sampling chip, a signal processing circuit, a control unit and a plurality of battery sampling chips, the single cells are electrically connected to the battery sampling chip, at least one of the single cells is electrically connected to the signal processing circuit, the signal processing circuit, the ADC sampling chip and the control unit are electrically connected in sequence, at least one of the battery sampling chips is electrically connected to the signal processing circuit, and a plurality of the battery sampling chips are electrically connected to the control unit respectively.

[0005] Furthermore, every two of the battery sampling chips are electrically connected to the same single battery.

[0006] Furthermore, a plurality of the single cells are electrically connected to a corresponding battery sampling chip.

[0007] Furthermore, the signal processing circuit is correspondingly connected to a single battery and a battery sampling chip.

[0008] Furthermore, the ADC sampling chip is AD4696.

[0009] Furthermore, a plurality of the single cells are connected in series with each other, and a plurality of the battery packs are connected in series with each other.

[0010] The present invention also provides a method for sampling and correcting the voltage of a single cell of a battery pack, comprising the following steps:

[0011] Setting at least one single battery in the battery pack as a reference battery;

[0012] The voltage of the reference battery is collected through the ADC sampling chip as the voltage reference value;

[0013] The voltage of all single cells in the battery pack is collected through the battery sampling chip as the voltage measurement value;

[0014] Compare the voltage measurement value of the reference battery with the voltage reference value to obtain the voltage deviation value of the battery sampling chip;

[0015] The voltage measurement value corresponding to each single battery is corrected by the voltage deviation value.

[0016] Furthermore, the method further comprises the following steps:

[0017] When there are multiple single cells and battery sampling chips, at least one battery sampling chip collects the voltage of the reference battery, and every two battery sampling chips in the remaining battery sampling chips collect the voltage of the same single cell at the same time;

[0018] Compare the voltage measurement value of the single cell collected by the calibrated battery sampling chip with the voltage measurement value of the same single cell collected by the battery sampling chip to be calibrated to obtain a voltage deviation value U2;

[0019] The other single cells sampled by the battery sampling chip to be calibrated are calibrated by using the voltage deviation value U1 and the voltage deviation value U2.

[0020] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0021] The present invention provides a battery pack single cell voltage sampling and correction circuit and method. The battery sampling chip and the ADC sampling chip are used to simultaneously collect the voltage of the same single cell. The voltage collected by the ADC sampling chip is used as a voltage reference value. The voltage reference value is compared with the voltage measurement value collected by the battery sampling chip to obtain the sampling error of the battery sampling chip. The voltage measurement values ​​of other single cells collected by the current battery sampling chip are corrected according to the sampling error of the current battery sampling chip to improve the accuracy of single cell voltage collection in the entire circuit, thereby improving the sampling accuracy of the voltage sampling and correction circuit. Redundancy design can be performed on software and hardware to make the calculation between the open circuit voltage and the remaining capacity of the battery more accurate in the application of the battery management system on lithium iron phosphate, thereby improving the remaining capacity (SOC) accuracy. The use cost is low and the method can be applied to the sampling needs of the single cell voltage in the battery management system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is a schematic diagram of a battery pack single cell voltage sampling and correction circuit provided by an embodiment of the present invention;

[0024] Figure 2 It is a flow chart of a method for sampling and correcting the voltage of a single cell of a battery pack provided in an embodiment of the present invention.

[0025] The reference numerals are as follows:

[0026] 1. Battery pack, 2. Battery group, 3. Single battery, 4. ADC sampling chip, 5. Signal processing circuit, 6. Control unit, 7. Battery sampling chip, 8. Communication cable. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] See also Figure 1 As shown, the present invention provides a battery pack single cell voltage sampling and correction circuit, wherein a battery pack 1 is provided with a plurality of battery packs 2 connected in sequence, a plurality of single cells 3 connected in sequence are provided in the battery pack 2, an ADC sampling chip 4, a signal processing circuit 5, a control unit 6 and a plurality of battery sampling chips 7, the single cells 3 are electrically connected to the battery sampling chip 7, at least one of the single cells 3 is electrically connected to the signal processing circuit 5, the signal processing circuit 5, the ADC sampling chip 4 and the control unit 6 are electrically connected in sequence, at least one of the battery sampling chips 7 is electrically connected to the signal processing circuit 5, and a plurality of battery sampling chips 7 are electrically connected to the control unit 6 respectively. Among them, the sampling accuracy of the ADC sampling chip 4 is greater than the sampling accuracy of the battery sampling chip 7, so as to improve the acquisition accuracy of the reference voltage value. The number of battery packs 2, single cells 3 and battery sampling chips 7 is greater than or equal to 2.

[0030] The ADC sampling chip 4 performs error correction on the battery sampling chip 7 that collects the voltage value of the same single battery 3 , so as to correct the voltage value of each single battery 3 collected by the battery sampling chip 7 .

[0031] Specifically, a plurality of battery sampling chips 7 are electrically connected to the control unit 6 via a communication cable 8 .

[0032] Specifically, a plurality of single cells 3 are connected in series with each other, and a plurality of battery packs 2 are connected in series with each other.

[0033] Preferably, the ADC sampling chip 4 is AD4696, the control unit 6 is STM32F103, and the battery sampling chip 7 is BQ76952.

[0034] Preferably, every two battery sampling chips 7 are electrically connected to the same single battery 3 .

[0035] The battery sampling chip 7 to be corrected is used to perform error correction on the battery sampling chip 7 to be corrected, so as to correct the sampling errors of the voltages collected between the battery sampling chips 7 and the battery sampling chip 7 itself, thereby reducing the complexity of the circuit structure and improving the correction efficiency.

[0036] As another embodiment, several battery sampling chips 7 may be electrically connected to the signal processing circuit 5, and the voltage of the same single battery 3 may not be collected between the several battery sampling chips 7. By setting multiple reference batteries, the ADC sampling chip 4 reads the voltage reference value of each reference battery respectively, compares the voltage measurement value of each reference battery collected by the battery sampling chip 7 with the voltage reference value, obtains the voltage deviation value of each battery sampling chip 7, and corrects the voltage measurement values ​​of all single batteries 3 collected by each battery sampling chip 7.

[0037] Preferably, a plurality of single cells 3 are electrically connected to one battery sampling chip 7 to reduce the use cost.

[0038] Specifically, each battery pack 2 corresponds to the battery sampling chip 7 one by one, and at this time, the number of single batteries 3 in each battery pack 2 should be limited.

[0039] The positive electrode and the negative electrode of each single battery 3 are electrically connected to the corresponding battery sampling chip 7 .

[0040] When actually connecting the circuit, the two adjacent battery sampling chips 7 jointly collect the voltage values ​​of the adjacent single batteries 3 between the two corresponding battery groups 2, so as to shorten the wiring length and reduce the wiring difficulty.

[0041] Preferably, the signal processing circuit 5 is connected to one single battery 3 and one battery sampling chip 7 correspondingly, so as to avoid increasing the complexity of the circuit structure due to setting multiple reference batteries.

[0042] Since temperature has little effect on the voltage value collected by the high-precision ADC sampling chip 4, the effect of temperature on voltage collection is ignored here.

[0043] Taking the single cell sampled by the ADC sampling chip 4 and the same single cell sampled by any two battery sampling chips 7 as examples, the working principle is further explained.

[0044] The ADC sampling chip 4 sends the collected voltage value of the battery to the control unit 6, and the control unit 6 uses the read voltage value as the voltage reference value, and then the control unit 6 reads the voltage value of each single battery 3 collected by the two battery sampling chips 7 through the communication cable 8. The control unit 6 first compares the voltage reference value of the single battery 3 collected by the ADC sampling chip 4 with the voltage measurement value of the same single battery 3 collected by the battery sampling chip 7 to be corrected, calculates the voltage deviation value U1 of the battery sampling chip 7 to be corrected, and calculates the actual voltage value of each single battery 3 measured by the battery sampling chip 7, and corrects the voltage measurement value of the battery sampling chip 7 to be corrected.

[0045] Then the control unit 6 compares the voltage value of the single battery 3 collected by the corrected battery sampling chip 7 and the next battery sampling chip 7 to be corrected, and calculates the voltage deviation value U2. By combining the voltage deviation value U2 and the voltage deviation value U1, the control unit 6 calculates the actual voltage value of each single battery 3 measured by the next battery sampling chip 7 to be corrected. Similarly, the voltage deviation value U3 between another battery sampling chip 7 to be corrected and the last corrected battery sampling chip 7 is calculated, and the voltage measurement value of the current battery sampling chip 7 to be corrected is corrected by combining the voltage deviation values ​​U3, U2, and U1.

[0046] like Figure 2 As shown, the present invention also provides a battery pack single cell voltage sampling and correction method, comprising the following steps:

[0047] Setting at least one single battery 3 in the battery pack 1 as a reference battery;

[0048] The voltage of the reference battery is collected by the ADC sampling chip 4 as a voltage reference value;

[0049] The voltage of all the single cells 3 in the battery pack 1 is collected by the battery sampling chip 7 as a voltage measurement value;

[0050] Compare the voltage measurement value of the reference battery with the voltage reference value to obtain the voltage deviation value U1 of the battery sampling chip 7;

[0051] The voltage measurement value corresponding to each single cell 3 is corrected by the voltage deviation value U1, and is applied to the correction control of the single cell voltage sampling and correction circuit of the battery pack provided above.

[0052] Preferably, the method further comprises the following steps:

[0053] When there are multiple single cells 3 and battery sampling chips 7, at least one battery sampling chip 7 collects the voltage of the reference battery, and every two battery sampling chips 7 of the remaining battery sampling chips 7 collect the voltage of the same single cell 3 at the same time;

[0054] Compare the voltage measurement value of the single battery 3 collected by the calibrated battery sampling chip 7 with the voltage measurement value of the same single battery 3 collected by the battery sampling chip 7 to be calibrated to obtain a voltage deviation value U2;

[0055] The voltage deviation value U1 and the voltage deviation value U2 are used to calibrate other single cells 3 sampled by the battery sampling chip 7 to be calibrated.

[0056] Each battery sampling chip 7 uses the voltage value of the reference battery collected by the same ADC sampling chip 4 as the reference voltage to calculate the voltage deviation of each battery sampling chip 7. In this way, the voltage sampling errors between the battery sampling chips 7 and the battery sampling chip 7 itself can be eliminated to the greatest extent through mutual correction between two adjacent battery sampling chips 7, thereby greatly improving the voltage collection accuracy of the single battery 3 in the entire voltage sampling correction circuit.

[0057] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A battery pack single cell voltage sampling and correction method, implemented by a battery pack single cell voltage sampling and correction circuit, characterized in that: The battery pack (1) is provided with a plurality of battery groups (2) connected in sequence, the battery group (2) is provided with a plurality of single cells (3) connected in sequence, including an ADC sampling chip (4), a signal processing circuit (5), a control unit (6) and a plurality of battery sampling chips (7), the single cells (3) are electrically connected to the battery sampling chip (7), at least one of the single cells (3) is electrically connected to the signal processing circuit (5), the signal processing circuit (5), the ADC sampling chip (4) and the control unit (6) are electrically connected in sequence, at least one of the battery sampling chips (7) is electrically connected to the signal processing circuit (5), and a plurality of the battery sampling chips (7) are electrically connected to the control unit (6) respectively; The method comprises the following steps: Setting at least one single battery (3) in the battery pack (1) as a reference battery; The voltage of the reference battery is collected by an ADC sampling chip (4) as a voltage reference value; The voltages of all the single cells (3) in the battery pack (1) are collected by means of a battery sampling chip (7) as voltage measurement values; Compare the voltage measurement value of the reference battery with the voltage reference value to obtain a voltage deviation value U1 of the battery sampling chip (7); Correcting the voltage measurement value corresponding to each single cell (3) by using the voltage deviation value U1; The following steps are also included: When there are multiple single cells (3) and battery sampling chips (7), at least one battery sampling chip (7) collects the voltage of a reference battery, and every two battery sampling chips (7) in the remaining battery sampling chips (7) collect the voltage of the same single cell (3) at the same time; Comparing the voltage measurement value of the single cell (3) collected by the calibrated battery sampling chip (7) with the voltage measurement value of the same single cell (3) collected by the battery sampling chip (7) to be calibrated, to obtain a voltage deviation value U2; The voltage deviation value U1 and the voltage deviation value U2 are used to calibrate other single cells (3) collected by the battery sampling chip (7) to be calibrated.

2. The method for sampling and correcting the voltage of a single cell of a battery pack according to claim 1, characterized in that: Every two of the battery sampling chips (7) are electrically connected to the same single battery (3).

3. The method for sampling and correcting the voltage of a single cell of a battery pack according to claim 2, characterized in that: The plurality of single cells (3) are electrically connected to a corresponding battery sampling chip (7).

4. The method for sampling and correcting the voltage of a single cell of a battery pack according to any one of claims 1 to 3, characterized in that: The signal processing circuit (5) is correspondingly connected to a single battery (3) and a battery sampling chip (7).

5. The method for sampling and correcting the voltage of a single cell of a battery pack according to any one of claims 1 to 3, characterized in that: The ADC sampling chip (4) is AD4696.

6. The method for sampling and correcting the voltage of a single cell of a battery pack according to any one of claims 1 to 3, characterized in that: A plurality of the single cells (3) are connected in series with each other, and a plurality of the battery packs (2) are connected in series with each other.

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