Voltage sampling method and device for lead-acid battery

Abstract

The invention discloses a voltage sampling method and device of a lead-acid battery, applied to a to-be-sampled battery pack comprising a plurality of lead-acid batteries connected in series, and the method comprises the following steps: collecting a discharge current when the lead-acid battery releases electric quantity; according to the discharge current, sampling voltage of the lead-acid battery is collected; collecting the total voltage of the battery pack to be sampled; and calibrating the sampling voltage of the lead-acid battery according to the total voltage to obtain the actual voltage of the lead-acid battery. By collecting the sampling voltage and the total voltage of the battery pack during discharging of the lead-acid battery, the problem of precision error caused by a traditional divider resistance network is avoided, and the accuracy of sampling the actual voltage of the single lead-acid battery is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lead-acid actual voltage sampling, and in particular to a lead-acid battery voltage sampling method and device. Background Art

[0002] Actual voltage is one of the important parameters reflecting the battery status, and its voltage value plays a key role in estimating the various operating states of the battery. Although the relationship between actual voltage and the remaining capacity (SOC) of the battery is not linear, it also reflects the battery SOC to a large extent. The actual voltage of the battery in open circuit and load states is also an important parameter reflecting the battery health status.

[0003] In the prior art, a battery pack consisting of 4 to 6 lead-acid batteries connected in series typically uses the same reference point. A voltage divider resistor is connected in series with each battery in the series, and the actual voltage is measured by voltage division to indirectly obtain the voltage of each lead-acid battery. However, the different precision of each voltage divider resistor affects the voltage sampling accuracy.

[0004] Therefore, in the prior art, the voltage sampling accuracy of a single lead-acid battery in a battery pack is low. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention aims to provide a lead-acid battery voltage sampling method and device, which can collect the actual voltage of each lead-acid battery without a voltage divider resistor, thereby improving the voltage sampling accuracy.

[0006] In order to solve the above problems, the present invention is implemented according to the following scheme:

[0007] A lead-acid battery voltage sampling method is provided, which is applied to a battery pack to be sampled including multiple lead-acid batteries connected in series, comprising:

[0008] collecting the discharge current of the lead-acid battery when it releases electricity;

[0009] collecting a sample voltage of the lead-acid battery according to the discharge current;

[0010] Collecting the total voltage of the battery pack to be sampled;

[0011] The sampled voltage of the lead-acid battery is calibrated according to the total voltage to obtain the actual voltage of the lead-acid battery.

[0012] Compared with the prior art, the voltage sampling method of a lead-acid battery of the present invention has the following beneficial effects: by collecting the sampled voltage of the lead-acid battery during discharge and the total voltage of the battery pack, the accuracy error problem caused by the traditional voltage divider resistor network is avoided, and the accuracy of the actual voltage sampling of a single lead-acid battery is effectively improved.

[0013] Optionally, collecting a sample voltage of the lead-acid battery according to the discharge current includes:

[0014] When the discharge current reaches a preset current, the voltage value of the lead-acid battery is collected and used as the sampled voltage.

[0015] Optionally, collecting the total voltage of the battery pack to be sampled includes:

[0016] Controlling all lead-acid batteries in the battery group to be sampled to release electricity at the same time;

[0017] The total voltage of the battery group to be sampled is determined according to the amount of electricity released simultaneously by all the lead-acid batteries.

[0018] Optionally, calibrating the sampled voltage of the lead-acid battery according to the total voltage to obtain the actual voltage of the lead-acid battery includes:

[0019] Determining a total sampling voltage based on the sampling voltages of all lead-acid batteries in the battery group to be sampled;

[0020] The sampled voltage of the lead-acid battery is calibrated according to the total voltage and the total sampled voltage to obtain the actual voltage of the lead-acid battery.

[0021] Optionally, calibrating the sampled voltage of the lead-acid battery according to the total voltage and the total sampled voltage to obtain the actual voltage of the lead-acid battery includes:

[0022] Determining a voltage proportion corresponding to the sampled voltage of the lead-acid battery according to the sampled voltage of the lead-acid battery and the total sampled voltage;

[0023] The actual voltage of the lead-acid battery is obtained according to the voltage proportion and the total voltage.

[0024] A lead-acid battery voltage sampling device is also provided, which is applied to the above-mentioned lead-acid battery voltage sampling method, comprising: a control module, a switch module, a flyback transformer, and a sampling module; the control module is connected to the switch module, the flyback transformer, and the sampling module; the flyback transformer is connected to the switch module and the sampling module; the lead-acid battery is connected to the switch module;

[0025] The control module controls the switch module to close the connection between the lead-acid battery and the flyback transformer to store the electricity released by the lead-acid battery or the battery pack to be sampled in the flyback transformer, and collects the discharge current when the lead-acid battery releases the electricity. The control module controls the switch module to cut off the connection between the lead-acid battery and the flyback transformer based on the discharge current. The control module determines the actual voltage of the lead-acid battery based on the electricity stored in the flyback transformer.

[0026] Optionally, the flyback transformer includes a primary coil and secondary coils whose number is the same as the number of the lead-acid batteries; the primary coil is connected to the sampling module and the control module, and the secondary coil is connected to the switch module.

[0027] Optionally, the switch module includes a plurality of switch units with the same structure, and the number of the switch units is the same as the number of the lead-acid batteries; the switch units are connected to the lead-acid batteries, the control module, and the secondary coil.

[0028] Optionally, the switching unit includes a switching tube and a signal output circuit, the switching tube is connected to the lead-acid battery and the signal output circuit, and the signal output circuit is connected to the secondary coil.

[0029] Optionally, the control module includes a processor and a memory, the memory storing at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement the voltage sampling method of a lead-acid battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of the voltage sampling method of the present invention;

[0031] Figure 2 This is a structural block diagram of the voltage sampling device of the present invention;

[0032] Figure 3 is a schematic diagram of a signal amplifying circuit of the present invention;

[0033] Figure 4 This is a partial circuit diagram of the voltage sampling device of the present invention;

[0034] Figure 5 Schematic diagram of the control chip of the present invention;

[0035] Figure 6 This is a timing diagram of the present invention sampling the actual voltage of a single lead-acid cell;

[0036] Explanation of the accompanying symbols: 1. Control module; 101. Control chip; 102. Signal amplification circuit; 103. Transformer control unit; 2. Switch module; 201. Switch tube; 202. Signal output circuit; 3. Flyback transformer; 4. Sampling module; 5. Battery pack to be sampled. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0038] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0039] See also Figure 1 As shown, a lead-acid battery voltage sampling method of the present invention is applied to a battery pack to be sampled including multiple lead-acid batteries connected in series, comprising:

[0040] S1: Collects the discharge current of the lead-acid battery when it releases electricity. The lead-acid battery is connected in parallel with the secondary coil of the flyback transformer. When the lead-acid battery releases electricity to the secondary coil of the flyback transformer, the secondary coil voltage of the flyback transformer will gradually increase, and the discharge current of the lead-acid battery will gradually decrease. When the discharge current of the lead-acid battery is 0A, the secondary coil voltage of the flyback transformer is equal to the actual voltage of the lead-acid battery.

[0041] S2: Collecting the sampling voltage of the lead-acid battery according to the discharge current, including: when the discharge current reaches a preset current, the lead-acid battery stops releasing electricity. In one embodiment of the present invention, the preset current is 0A. When the discharge current reaches the preset current 0A, the secondary coil voltage of the flyback transformer is the same as the actual lead-acid voltage; determining the sampling voltage of the lead-acid battery according to the amount of electricity released by the lead-acid battery. In the flyback transformer, the amount of electricity released by the lead-acid battery to the secondary coil of the flyback transformer will be stored in the primary coil of the flyback transformer. The amount of electricity stored in the primary coil of the flyback transformer (the amount of electricity released by the lead-acid battery) is specifically the voltage value of the primary coil, and the sampling voltage of the lead-acid battery can be determined.

[0042] S3: Collecting the total voltage of the battery group to be sampled, including: controlling all lead-acid batteries in the battery group to be sampled to release electricity simultaneously, the flyback transformer includes multiple secondary coils, and each lead-acid battery in the battery group to be sampled is connected in parallel with a secondary coil; determining the total voltage of the battery group to be sampled based on the electricity released simultaneously by all lead-acid batteries, in the flyback transformer, all lead-acid batteries in the battery group to be sampled simultaneously release electricity to the secondary coils connected in parallel, which will be stored in the primary coil of the flyback transformer, and the total voltage of the battery group to be sampled is determined by the electricity stored in the primary coil of the flyback transformer (the electricity released simultaneously by all lead-acid batteries).

[0043] S4: Calibrating the sampling voltage of the lead-acid battery according to the total voltage to obtain the actual voltage of the lead-acid battery, including: determining the total sampling voltage according to the sampling voltages of all lead-acid batteries in the battery group to be sampled; and calibrating the sampling voltage of the lead-acid battery according to the total voltage and the total sampling voltage to obtain the actual voltage of the lead-acid battery.

[0044] In one embodiment of the present invention, the sampled voltage of the lead-acid battery is calibrated according to the total voltage and the total sampled voltage to obtain the actual voltage of the lead-acid battery, including: determining the voltage proportion corresponding to the sampled voltage of the lead-acid battery according to the sampled voltage and the total sampled voltage of the lead-acid battery; and determining the actual voltage of the lead-acid battery according to the voltage proportion and the total voltage.

[0045] See also Figure 2 As shown, a voltage sampling device for a lead-acid battery of the present invention includes: a control module 1, a switch module 2, a flyback transformer 3 and a sampling module 4; the control module 1 is connected to the switch module 2, the flyback transformer 3 and the sampling module 4, and the flyback transformer 3 is connected to the switch module 2 and the sampling module 4; the battery group 5 to be sampled includes multiple lead-acid batteries connected in series, and the lead-acid batteries are connected to the control module 1 and the flyback transformer 3.

[0046] The control module 1 controls the switch module 2 to close the connection between the lead-acid battery and the flyback transformer 3 to store the electricity released by the lead-acid battery or the battery pack 5 to be sampled in the flyback transformer 3, and collects the discharge current when the lead-acid battery releases the electricity. The control module 1 controls the switch module 2 to cut off the connection between the lead-acid battery and the flyback transformer 3 according to the discharge current. The control module 1 determines the sampling voltage of the lead-acid battery based on the electricity stored in the flyback transformer 3.

[0047] In one embodiment of the present invention, the flyback transformer 3 includes a primary coil and secondary coils having the same number as the lead-acid batteries. Taking the resistor to be controlled formed by 6 lead-acid batteries commonly connected in series on the market as an example, there are 6 secondary coils in total and 2 primary coils. The turns ratio of the primary coil to the secondary coil is 3:1. The primary coil is connected to the sampling module 4 and the control module 1, the first input end of the secondary coil is connected to the switch module 2, and the second input end of the secondary coil is connected to the lead-acid battery.

[0048] In one embodiment of the present invention, the switch module 2 includes multiple switch units with the same structure, and the number of the switch units is the same as the number of lead-acid batteries; each switch unit is connected to a lead-acid battery, the control module 1, and the first input end of the secondary coil; wherein the switch unit includes a switch tube 201 which is a MOS tube and a signal output circuit 202, the switch tube 201 is connected to the control module 1 and the signal output circuit 202, and the signal output circuit 202 is connected to the first input end of the secondary coil.

[0049] The control module 1 includes an STM32F103C8T6 control chip 101, a signal amplification circuit 102, and a transformer control unit 103. The control chip 101 is connected to the signal amplification circuit 102, the transformer control unit 103, the sampling module 4, and the battery pack 5 to be sampled. The signal amplification circuit 102 is connected to the switch 201, and the transformer control unit 103 is connected to the primary coil. The active balancing device of the present invention is described below using a battery pack 5 to be sampled, consisting of six lead-acid batteries connected in series, as an example.

[0050] See also Figure 3-5 As shown, the negative electrode of the lead-acid battery is connected to the signal amplifying circuit 102 to form a current loop of the positive electrode of the lead-acid battery - the second input terminal of the secondary coil - the first input terminal of the secondary coil - the switching unit - the signal amplifying circuit 102 - the negative electrode of the lead-acid battery. The initial signal output by the control chip 101 is amplified by the signal amplifying circuit 102 to obtain six control signals S1, S2, ..., S6. The control signals are used to control the switching state of the switch tube 201. When the signal amplifying circuit 102 has no output, the lead-acid battery will not self-discharge or charge, so as to avoid the lead-acid battery from self-consuming power when at rest, thereby extending the life of the lead-acid battery.

[0051] When the switch tube 201 is closed, the connection between the switch tube 201 and the first input end of the secondary coil is closed. At this time, the current loop between the switch tube 201-the first input end of the secondary coil-the second input end of the secondary coil-the lead-acid battery is closed, that is, the connection (current loop) between the lead-acid battery and the flyback transformer 3 is closed. At this time, the lead-acid battery releases electricity to the secondary coil, and the primary coil stores the electricity released by the lead-acid battery; when the switch tube 201 is disconnected, the connection between the switch tube 201 and the first input end of the secondary coil is disconnected. At this time, the current loop between the switch unit-the first input end of the secondary coil-the second input end of the secondary coil-the lead-acid battery is disconnected, that is, the connection (current loop) between the lead-acid battery and the flyback transformer 3 is disconnected, and at this time the primary coil releases electricity to the lead-acid battery.

[0052] The sampling module 4 feeds back the voltage of each lead-acid battery via the voltage signal Umux, thereby enabling the voltage sampling of six lead-acid batteries using only one I / O port (port PA1) of the control chip 101. Simultaneously, the total voltage of the batteries to be sampled is sampled via port PA3 of the control chip. Specifically, the control chip 101 is connected to the positive electrode of the lead-acid battery B6, and the ground wire is connected to the negative electrode of the lead-acid battery B1. The transformer control unit 103 includes a MOS transistor T7. The control signal Prim_L generated by the control chip 101 is used to switch the charge and discharge state of the primary coil of the flyback transformer 3, specifically to control the on / off state of the MOS transistor T7. When the MOS transistor T7 is on, the flyback transformer 3 is in the charging state, and when the MOS transistor T7 is closed, the flyback transformer 3 is in the discharging state.

[0053] See also Figure 6 The figure below shows the timing diagram for sampling the actual voltage of a single lead-acid battery. Next, we will take lead-acid battery B1 as an example to explain the working process of the voltage sampling device in detail:

[0054] When the sampling module 4 detects that the flyback transformer has no energy (i.e., 0V), it feeds back the signal DEGAUSS to the pin PA11 of the control chip 101. The control signal Prim_L of the pin PA10 outputs a high level to control the MOS tube T7 to be closed (conducted). The battery pack 5 to be sampled charges the primary coil and generates a charging current Iprim. Figure 6 Stages 2 to 3 in the process.

[0055] See also Figure 6 In stages 3 and 4, when the charging time reaches the set value, the control chip 101 outputs a low-level control signal Prim_L to control the MOS transistor T7 to turn on. Since the inductor current cannot change suddenly, the charging current gradually decreases to 0A. At the same time, the voltage signal Umux collected by the sampling module 4 gradually increases.

[0056] The control chip 101 outputs a control signal S1 for turning on the switch tube T8. When the lead-acid battery B1 discharges to its secondary coil connected in series and stores through the primary coil, the lead-acid battery B1 will generate a discharge current I S1 As the voltage of the secondary coil connected in parallel with the lead-acid battery B1 rises, the discharge current I S1 Also gradually decreases; when the voltage of the secondary coil is equal to the voltage of the lead-acid battery B1, the discharge current I S1 is 0A, at this time the voltage signal Umux collected by the sampling module 4 is equal to the voltage of the secondary coil*turns ratio.

[0057] In the flyback transformer 3, the turns ratio of the secondary coil to the primary coil is 3:1. Based on the turns ratio and the voltage signal Umux, the voltage of the lead-acid battery B1 is calculated as follows: U B1 =Umux / 3.

[0058] When the discharge current I S1 After zero-crossing sampling to Umux, the control chip 101 outputs a low-level control signal S1 to close the switch tube T8, and the discharge current I S1 Gradually drops to 0. At this time, the voltage signal Umux gradually drops until it reaches 0V. When the sampling module 4 monitors that the flyback transformer 3 has no energy (drops to 0V), it feeds back to the pin PA11 of the control chip 101 through the signal DEGAUSS.

[0059] Repeat the above steps for each lead-acid battery and collect the voltage value (sampling voltage) of each lead-acid battery.

[0060] After the sampling module 4 collects the voltage of each lead-acid battery and the total voltage of the battery group to be sampled 5, the total sampled voltage is determined based on the voltages of all lead-acid batteries in the battery group to be sampled. The voltage proportion corresponding to the sampled voltage is determined based on the sampled voltage of each lead-acid battery and the total sampled voltage. The actual voltage of the lead-acid battery is obtained based on the voltage proportion and the total voltage. The specific calculation formula is as follows:

[0061] U 实际 =U 总 ×U 采样 / U 总采样

[0062] Among them, U 电池 is the actual voltage of a single lead-acid battery, U 总 is the total voltage of the battery pack 5 to be sampled, U 采样 is the sampling voltage of a single lead-acid battery, U 总采样 is the total sampled voltage.

[0063] The present invention uses the primary coil and secondary coil of the flyback transformer to achieve the purpose of receiving the voltages of multiple lead-acid batteries with only one I / O port of the control chip. There is no need to connect a voltage divider resistor in series with each lead-acid battery, thereby indirectly measuring the actual voltage of the lead-acid battery and avoiding the influence of the accuracy of the voltage divider resistor. At the same time, there is no need to equip each lead-acid battery with an isolation element and an I / O port to receive the voltage, which effectively reduces costs.

[0064] In one embodiment of the present invention, the control module includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement the above-mentioned voltage sampling method.

[0065] The processor can be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0066] The memory can be used to store the computer program or module, and the processor implements the various functions of the voltage sampling method by running or executing the computer program or module stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required for a function, etc.; the data storage area can store data created based on the use of the mobile phone, etc. In addition, the memory can include a high-speed random access memory and can also include a non-volatile memory, such as a hard disk, internal memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0067] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A lead-acid battery voltage sampling method, applied to a battery pack to be sampled comprising a plurality of lead-acid batteries connected in series, characterized in that: include: collecting the discharge current of the lead-acid battery when it releases electricity; collecting a sample voltage of the lead-acid battery according to the discharge current; Collecting the total voltage of the battery pack to be sampled; The sampled voltage of the lead-acid battery is calibrated according to the total voltage to obtain the actual voltage of the lead-acid battery.

2. The voltage sampling method of a lead-acid battery according to claim 1, characterized in that: Collecting a sample voltage of the lead-acid battery according to the discharge current includes: When the discharge current reaches a preset current, the voltage value of the lead-acid battery is collected and used as the sampled voltage.

3. The voltage sampling method of a lead-acid battery according to claim 1, characterized in that: Collecting the total voltage of the battery pack to be sampled includes: Controlling all lead-acid batteries in the battery group to be sampled to release electricity at the same time; The total voltage of the battery group to be sampled is determined according to the amount of electricity released simultaneously by all the lead-acid batteries.

4. The voltage sampling method of a lead-acid battery according to claim 1, characterized in that: Calibrating the sampled voltage of the lead-acid battery according to the total voltage to obtain the actual voltage of the lead-acid battery includes: Determining a total sampling voltage based on the sampling voltages of all lead-acid batteries in the battery group to be sampled; The sampled voltage of the lead-acid battery is calibrated according to the total voltage and the total sampled voltage to obtain the actual voltage of the lead-acid battery.

5. The voltage sampling method of a lead-acid battery according to claim 4, characterized in that: Calibrating the sampled voltage of the lead-acid battery according to the total voltage and the total sampled voltage to obtain the actual voltage of the lead-acid battery includes: Determining a voltage proportion corresponding to the sampled voltage of the lead-acid battery according to the sampled voltage of the lead-acid battery and the total sampled voltage; The actual voltage of the lead-acid battery is obtained according to the voltage proportion and the total voltage.

6. A lead-acid battery voltage sampling device, applied to the lead-acid battery voltage sampling method according to claims 1-5, characterized in that: include: A control module, a switch module, a flyback transformer and a sampling module; the control module is connected to the switch module, the flyback transformer and the sampling module, the flyback transformer is connected to the switch module and the sampling module; the lead-acid battery is connected to the switch module; The control module controls the switch module to close the connection between the lead-acid battery and the flyback transformer to store the electricity released by the lead-acid battery or the battery pack to be sampled in the flyback transformer, and collects the discharge current when the lead-acid battery releases the electricity. The control module controls the switch module to cut off the connection between the lead-acid battery and the flyback transformer based on the discharge current. The control module determines the actual voltage of the lead-acid battery based on the electricity stored in the flyback transformer.

7. The voltage sampling device for a lead-acid battery according to claim 6, characterized in that: The flyback transformer includes a primary coil and secondary coils having the same number as the lead-acid batteries; the primary coil is connected to the sampling module and the control module, and the secondary coil is connected to the switch module.

8. The voltage sampling device for a lead-acid battery according to claim 7, characterized in that: The switch module includes a plurality of switch units with the same structure, and the number of the switch units is the same as the number of the lead-acid batteries; the switch units are connected to the lead-acid batteries, the control module, and the secondary coil.

9. The voltage sampling device for a lead-acid battery according to claim 8, characterized in that: The switch unit includes a switch tube and a signal output circuit. The switch tube is connected to the lead-acid battery and the signal output circuit. The signal output circuit is connected to the secondary coil.

10. The voltage sampling device for a lead-acid battery according to claim 9, characterized in that: The control module includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement a lead-acid battery voltage sampling method according to any one of claims 1 to 5.

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