Multi-channel battery voltage detection circuit with equalization function

Abstract

The invention relates to battery voltage detection, in particular to a multichannel battery voltage detection circuit with an equalization function, which comprises a multiplexer module connected between a battery pack to be detected and an analog front end sampling chip AFE, and under the control of a controller MCU, a battery voltage signal is transmitted to the analog front end sampling chip AFE by selecting a corresponding channel; meanwhile, carrying out passive equalization and active equalization on the battery pack to be tested by selecting corresponding channels; the analog front-end sampling chip AFE is connected between the multiplexer module and the controller MCU, sends the battery voltage signal to the controller MCU to realize battery voltage detection, and realizes passive equalization of the battery pack to be detected by utilizing a discharge channel of the analog front-end sampling chip AFE under the control of the controller MCU; according to the technical scheme provided by the invention, the defects that the voltage of each lithium battery in the parallel battery module cannot be accurately and quickly detected and the function of the battery voltage detection circuit is single in the prior art can be effectively overcome.

Description

Technical Field

[0001] The present invention relates to battery voltage detection, and particularly to a multi-channel battery voltage detection circuit with an equalization function. Background Art

[0002] At present, for the voltage detection of parallel battery modules in a lithium battery pack, the corresponding circuits have problems such as complicated design, a large number of required components, and high costs. Moreover, in some working conditions, it is impossible to accurately and quickly detect the voltage of each lithium battery in the parallel battery module. In addition, the existing equalization methods for lithium battery packs are generally divided into passive equalization and active equalization. Passive equalization generally uses discharge resistors, resulting in waste of electric energy; active equalization often uses DC-DC modules, which have problems such as high costs and difficulties in miniaturization. Summary of the Invention

[0003] (1) Technical Problems to be Solved

[0004] In view of the above-mentioned disadvantages of the prior art, the present invention provides a multi-channel battery voltage detection circuit with an equalization function, which can effectively overcome the defects of the prior art that it is impossible to accurately and quickly detect the voltage of each lithium battery in the parallel battery module and the single function of the battery voltage detection circuit.

[0005] (2) Technical Solutions

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0007] A multi-channel battery voltage detection circuit with an equalization function includes a battery pack to be measured, a power supply selection module, a multiplexer module, an analog front-end sampling chip AFE, and a controller MCU;

[0008] The power supply selection module is connected to the battery pack to be measured and selects the power supply battery string in the power supply path under the control of the controller MCU;

[0009] The multiplexer module is connected between the battery pack to be measured and the analog front-end sampling chip AFE. Under the control of the controller MCU, it transmits the battery voltage signal to the analog front-end sampling chip AFE by selecting the corresponding channel, and at the same time performs passive equalization and active equalization on the battery pack to be measured by selecting the corresponding channel;

[0010] The analog front-end sampling chip AFE is connected between the multiplexer module and the controller MCU, sends the battery voltage signal to the controller MCU to realize battery voltage detection, and at the same time, under the control of the controller MCU, uses its own discharge channel to realize passive equalization of the battery pack to be measured.

[0011] Preferably, each of the power supply battery strings is connected to the power supply path through a power supply selection module. Each battery cell in each row of the battery pack to be tested is connected to the input ends of all the selectors in the corresponding row of the multiplexer module. The output ends of all the selectors in each row of the multiplexer module are connected together and connected to the input end of the analog front-end sampling chip AFE. The output end of the analog front-end sampling chip AFE is connected to the controller MCU;

[0012] The power supply selection module is connected to the controller MCU. All the selectors in the multiplexer module are connected to the controller MCU. The analog front-end sampling chip AFE is connected to the controller MCU;

[0013] Among them, the battery pack to be tested is formed by connecting multiple power supply battery strings in parallel. Each power supply battery string is formed by connecting multiple battery cells in series. The battery pack to be tested is formed by multiple battery cells in the form of a battery cell array. The multiplexer module is formed by multiple selectors in the form of a selector array.

[0014] Preferably, the battery pack to be tested is formed by connecting a first power supply battery string, a second power supply battery string, a third power supply battery string, and a fourth power supply battery string in parallel. The first power supply battery string is formed by connecting battery cells C11, C21, C31, and C41 in series. The second power supply battery string is formed by connecting battery cells C12, C22, C32, and C42 in series. The third power supply battery string is formed by connecting battery cells C13, C23, C33, and C43 in series. The fourth power supply battery string is formed by connecting battery cells C14, C24, C34, and C44 in series;

[0015] The power supply selection module includes switches M1, M2, M3, and M4. The gates of the switches M1, M2, M3, and M4 are all connected to the controller MCU. The drains of the switches M1, M2, M3, and M4 are all connected to the power supply path. The sources of the switches M1, M2, M3, and M4 are respectively connected to the positive electrodes of battery cells C41, C42, C43, and C44. The negative electrodes of battery cells C11, C12, C13, and C14 are all grounded.

[0016] Preferably, the multiplexer module includes selectors PC11, PC12, PC13, PC14, PC21, PC22, PC23, PC24, PC31, PC32, PC33, PC34, PC41, PC42, PC43, and PC44. All the selectors in the multiplexer module are connected to the controller MCU;

[0017] The input terminals of the selectors PC11, PC12, PC13, and PC14 are all connected to the batteries C11, C12, C13, and C14. The output terminals of the selectors PC11, PC12, PC13, and PC14 are connected together and connected to the input terminal of the analog front-end sampling chip AFE through the filter capacitor cap1;

[0018] The input terminals of the selectors PC21, PC22, PC23, and PC24 are all connected to the batteries C21, C22, C23, and C24. The output terminals of the selectors PC21, PC22, PC23, and PC24 are connected together and connected to the input terminal of the analog front-end sampling chip AFE through the filter capacitor cap2;

[0019] The input terminals of the selectors PC31, PC32, PC33, and PC34 are all connected to the batteries C31, C32, C33, and C34. The output terminals of the selectors PC31, PC32, PC33, and PC34 are connected together and connected to the input terminal of the analog front-end sampling chip AFE through the filter capacitor cap3;

[0020] The input terminals of the selectors PC41, PC42, PC43, and PC44 are all connected to the batteries C41, C42, C43, and C44. The output terminals of the selectors PC41, PC42, PC43, and PC44 are connected together and connected to the input terminal of the analog front-end sampling chip AFE through the filter capacitor cap4.

[0021] Preferably, each selector in the multiplexer module has four channels. When the selector receives the external signal 00 sent by the controller MCU, it selects the first channel. When the selector receives the external signal 01 sent by the controller MCU, it selects the second channel. When the selector receives the external signal 10 sent by the controller MCU, it selects the third channel. When the selector receives the external signal 11 sent by the controller MCU, it selects the fourth channel.

[0022] Preferably, communication between the analog front-end sampling chip AFE and the controller MCU is selected to be carried out through the SPI or CAN protocol according to the working characteristics. The controller MCU receives the battery voltage signal sent by the analog front-end sampling chip AFE and performs arithmetic processing to detect the battery voltage.

[0023] (III) Beneficial effects

[0024] Compared with the prior art, a multi-channel battery voltage detection circuit with an equalization function provided by the present invention can not only detect the battery voltage of each battery cell in the power supply battery string, but also simultaneously detect the battery voltages of multiple battery cells in different power supply battery strings. In addition, this circuit has a built-in battery pack equalization function, which can achieve effective equalization between different power supply battery strings. Moreover, this circuit has strong scalability, facilitating the expansion of the scale of the battery pack to be tested, compared with the traditional analog front-end test circuit. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 It is a circuit schematic diagram of the present invention. Detailed Embodiments

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0028] A multi-channel battery voltage detection circuit with an equalization function includes a battery pack to be tested, a power supply selection module, a multiplexer module, an analog front-end sampling chip AFE, and a controller MCU;

[0029] The power supply selection module is connected to the battery pack to be tested and selects the power supply battery string in the power supply path under the control of the controller MCU;

[0030] The multiplexer module is connected between the battery pack to be tested and the analog front-end sampling chip AFE. Under the control of the controller MCU, it transmits the battery voltage signal to the analog front-end sampling chip AFE by selecting the corresponding channel, and simultaneously performs passive equalization and active equalization on the battery pack to be tested by selecting the corresponding channel;

[0031] The analog front-end sampling chip AFE is connected between the multiplexer module and the controller MCU, sends the battery voltage signal to the controller MCU to achieve battery voltage detection, and at the same time, under the control of the controller MCU, uses its own discharge channel to achieve passive equalization of the battery pack to be tested.

[0032] Each power supply battery string is connected to the power supply path through a power supply selection module. Each battery cell in each row of the battery pack to be tested is connected to the input terminals of all the selectors in the corresponding row of the multiplexer module. The output terminals of all the selectors in each row of the multiplexer module are connected together and connected to the input terminal of the analog front-end sampling chip AFE. The output terminal of the analog front-end sampling chip AFE is connected to the controller MCU;

[0033] The power supply selection module is connected to the controller MCU. All the selectors in the multiplexer module are connected to the controller MCU. The analog front-end sampling chip AFE is connected to the controller MCU;

[0034] Among them, the battery pack to be tested is composed of multiple power supply battery strings connected in parallel. Each power supply battery string is composed of multiple battery cells connected in series. The battery pack to be tested is composed of multiple battery cells in the form of a battery cell array. The multiplexer module is composed of multiple selectors in the form of a selector array.

[0035] According to the working characteristics, communication between the analog front-end sampling chip AFE and the controller MCU is selected to be carried out through the SPI or CAN protocol. The controller MCU receives the battery voltage signal sent by the analog front-end sampling chip AFE and performs arithmetic processing to detect the battery voltage.

[0036] As Figure 1 shown, the battery pack to be tested is composed of the first power supply battery string, the second power supply battery string, the third power supply battery string, and the fourth power supply battery string connected in parallel. The first power supply battery string is composed of battery cells C11, C21, C31, and C41 connected in series. The second power supply battery string is composed of battery cells C12, C22, C32, and C42 connected in series. The third power supply battery string is composed of battery cells C13, C23, C33, and C43 connected in series. The fourth power supply battery string is composed of battery cells C14, C24, C34, and C44 connected in series;

[0037] The power supply selection module includes switches M1, M2, M3, and M4. The gates of switches M1, M2, M3, and M4 are all connected to the controller MCU. The drains of switches M1, M2, M3, and M4 are all connected to the power supply path. The sources of switches M1, M2, M3, and M4 are respectively connected to the positive electrodes of battery cells C41, C42, C43, and C44. The negative electrodes of battery cells C11, C12, C13, and C14 are all grounded.

[0038] The multiplexer module includes selectors PC11, PC12, PC13, PC14, PC21, PC22, PC23, PC24, PC31, PC32, PC33, PC34, PC41, PC42, PC43, and PC44. All the selectors in the multiplexer module are connected to the controller MCU;

[0039] The input ends of the selectors PC11, PC12, PC13, and PC14 are all connected to the batteries C11, C12, C13, and C14. The output ends of the selectors PC11, PC12, PC13, and PC14 are connected together and connected to the input end of the analog front-end sampling chip AFE through a filter capacitor cap1 (which has a filtering function to stabilize voltage fluctuations).

[0040] The input ends of the selectors PC21, PC22, PC23, and PC24 are all connected to the batteries C21, C22, C23, and C24. The output ends of the selectors PC21, PC22, PC23, and PC24 are connected together and connected to the input end of the analog front-end sampling chip AFE through a filter capacitor cap2 (which has a filtering function to stabilize voltage fluctuations).

[0041] The input ends of the selectors PC31, PC32, PC33, and PC34 are all connected to the batteries C31, C32, C33, and C34. The output ends of the selectors PC31, PC32, PC33, and PC34 are connected together and connected to the input end of the analog front-end sampling chip AFE through a filter capacitor cap3 (which has a filtering function to stabilize voltage fluctuations).

[0042] The input ends of the selectors PC41, PC42, PC43, and PC44 are all connected to the batteries C41, C42, C43, and C44. The output ends of the selectors PC41, PC42, PC43, and PC44 are connected together and connected to the input end of the analog front-end sampling chip AFE through a filter capacitor cap4 (which has a filtering function to stabilize voltage fluctuations).

[0043] Each selector in the multiplexer module has four channels. When the selector receives the external signal 00 sent by the controller MCU, it selects the first channel. When the selector receives the external signal 01 sent by the controller MCU, it selects the second channel. When the selector receives the external signal 10 sent by the controller MCU, it selects the third channel. When the selector receives the external signal 11 sent by the controller MCU, it selects the fourth channel.

[0044] It should be noted that Figure 1 only one circuit form that can achieve the technical purpose of this application is given, and the scale of the battery pack to be measured and the multiplexer module can also be adjusted according to needs. For example, the multiplexer module can be adjusted from a 4*4 selector array form to a 4*2 selector array form, etc.

[0045] To better illustrate the technical solution of this application, the working process of the technical solution of this application will be described in detail below in combination with several implemented functions:

[0046] 1) Perform battery voltage detection on the battery C41

[0047] The controller MCU sends the external signal X0X1 = 00 to the selector PC41, the external signal X8X9 = 00 to the selector PC42, the external signal X16X17 = 00 to the selector PC43, and the external signal X24X25 = 00 to the selector PC44, so that the selectors PC41 / PC42 / PC43 / PC44 select the first channel, and connect the positive and negative electrodes of the battery C41 to the voltage measurement endpoints of the analog front-end sampling chip AFE through B4+ and B4- respectively;

[0048] Since the voltage measurement endpoints of the analog front-end sampling chip AFE are in a high-impedance state, the resistance of the selector-selected channel is small (usually 0.1 - 1 Ω), and the input current in the measurement mode is extremely small (usually a few microamperes or even smaller), so the voltage error introduced by the resistance of the selector-selected channel can be ignored.

[0049] 2) Simultaneously perform battery voltage detection on the batteries C11, C22, C33, and C44

[0050] The controller MCU sends the external signals X0X1 / X8X9 / X16X17 / X24X25 = 11 to the selectors PC41, PC42, PC43, and PC44, so that the selectors PC41 / PC42 / PC43 / PC44 select the fourth channel, and connect the positive and negative electrodes of the battery C44 to the voltage measurement endpoints of the analog front-end sampling chip AFE through B4+ and B4- respectively;

[0051] The controller MCU sends the external signals X2X3 / X10X11 / X18X19 / X26X27 = 10 to the selectors PC31, PC32, PC33, and PC34, so that the selectors PC31 / PC32 / PC33 / PC34 select the third channel, and connect the positive and negative electrodes of the battery C33 to the voltage measurement endpoints of the analog front-end sampling chip AFE through B3+ and B3- respectively;

[0052] The controller MCU sends the external signals X4X5 / X12X13 / X20X21 / X28X29 = 01 to the selectors PC21, PC22, PC23, and PC24, so that the selectors PC21 / PC22 / PC23 / PC24 select the second channel, and connect the positive and negative electrodes of the battery C22 to the voltage measurement endpoints of the analog front-end sampling chip AFE through B2+ and B2- respectively;

[0053] The controller MCU sends the external signal X6X7 / X14X15 / X22X23 / X20X31 = 00 to the selectors PC11, PC12, PC13, PC14, so that the selectors PC11 / PC12 / PC13 / PC14 select the first channel, and connect the positive and negative electrodes of the battery C11 to the voltage measurement endpoints of the analog front-end sampling chip AFE through B1+ and B1- respectively;

[0054] In addition to the battery cell combinations mentioned above, battery voltage detection of many other complex battery cell combinations can also be achieved, so as to meet the complex and changeable battery test requirements.

[0055] 3) Perform passive equalization on the battery C44

[0056] When the voltage of the battery C44 is too high, voltage equalization can be achieved by discharging it. First, the controller MCU sends the external signal X0X1 / X8X9 / X16X17 / X24X25 = 11 to the selectors PC41, PC42, PC43, PC44, so that the selectors PC41 / PC42 / PC43 / PC44 select the fourth channel, and connect the positive and negative electrodes of the battery C44 to the analog front-end sampling chip AFE through B4+ and B4- respectively. Subsequently, the controller MCU controls the analog front-end sampling chip AFE to open the discharge channel between B4+ and B4- to perform passive equalization on the battery C44;

[0057] The discharge current is determined by the voltage of the battery C44 and the resistance of the discharge channel. Since the resistance of the channel selected by the selector is small (usually 0.1 - 1 Ω), the discharge current is mainly limited by the internal equalization ability in the analog front-end sampling chip AFE.

[0058] 4) Perform active equalization on the battery C42 using the battery C41

[0059] When the voltage of the battery C42 is 4.2V and the voltage of the battery C41 is 4.1V, voltage equalization can be achieved by charging the battery C41. First, the controller MCU sends the external signal X0X1 / X8X9 = 00 to the selectors PC41, PC42, so that the selectors PC41 / PC42 select the first channel, and connect the positive and negative electrodes of the battery C41 to B4+ and B4- respectively;

[0060] Subsequently, the controller MCU sends external signals X16X17 / X24X25 = 01 to the selectors PC43 and PC44, so that the selectors PC43 / PC44 select the second channel, connect the positive and negative electrodes of the battery C42 to B4+ and B4- respectively, so that the positive and negative electrodes of the battery C41 are respectively connected to the positive and negative electrodes of C42, forming a charging circuit, and the battery C42 charges the battery C41 to perform active equalization on the battery C42.

[0061] 5) Use the batteries C42, C43, and C44 to perform active equalization on the battery C41

[0062] When the voltage of the battery C41 is too high, voltage equalization can be achieved by charging the batteries C42, C43, and C44. The controller MCU sends external signals X0X1 = 00, X8X9 = 01, X16X17 = 10, and X24X25 = 11 to the selectors PC41, PC42, PC43, and PC44 respectively, so that the selectors PC41, PC42, PC43, and PC44 select the first channel, the second channel, the third channel, and the fourth channel respectively, so that the positive and negative electrodes of the batteries C41, C42, C43, and C44 are respectively connected to B4+ and B4-, forming a charging circuit, and the battery C41 charges the batteries C42, C43, and C44 to perform active equalization on the battery C41;

[0063] As the charging progresses, the voltage difference between the batteries continuously shrinks, and it has the characteristic of charging current attenuation. The charging current is determined by the voltage difference, the battery internal resistance, and the resistance of the selector-selected channel. The charging current can be changed by selecting different selectors;

[0064] In addition to the battery cell combinations mentioned above, charging active equalization of other various complex battery cell combinations can also be achieved. For example, single-cell to two-cell, two-cell to one-cell, two-cell to two-cell and other combination methods can be specifically achieved by the controller MCU configuring external signals X0~X31.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-channel battery voltage detection circuit with an equalization function, characterized in that: It includes a battery pack to be tested, a power supply selection module, a multiplexer module, an analog front-end sampling chip AFE, and a controller MCU; The power supply selection module is connected to the battery pack to be tested and selects the power supply battery string to be connected to the power supply path under the control of the controller MCU; The multiplexer module is connected between the battery pack to be tested and the analog front-end sampling chip AFE. Under the control of the controller MCU, it transmits the battery voltage signal to the analog front-end sampling chip AFE by selecting the corresponding channel, and at the same time performs passive equalization and active equalization on the battery pack to be tested by selecting the corresponding channel; The analog front-end sampling chip AFE is connected between the multiplexer module and the controller MCU, sends the battery voltage signal to the controller MCU to achieve battery voltage detection, and at the same time, under the control of the controller MCU, uses its own discharge channel to achieve passive equalization of the battery pack to be tested.

2. The multi-channel battery voltage detection circuit with an equalization function according to claim 1, characterized in that: Each of the power supply battery strings is connected to the power supply path through the power supply selection module. Each battery cell in each row of the battery pack to be tested is connected to the input ends of all selectors in the corresponding row of the multiplexer module. The output ends of all selectors in each row of the multiplexer module are connected together and connected to the input end of the analog front-end sampling chip AFE, and the output end of the analog front-end sampling chip AFE is connected to the controller MCU; The power supply selection module is connected to the controller MCU, all selectors in the multiplexer module are connected to the controller MCU, and the analog front-end sampling chip AFE is connected to the controller MCU; Among them, the battery pack to be tested is composed of multiple power supply battery strings connected in parallel. Each power supply battery string is composed of multiple battery cells connected in series. The battery pack to be tested is composed of multiple battery cells in the form of a battery cell array, and the multiplexer module is composed of multiple selectors in the form of a selector array.

3. The multi-channel battery voltage detection circuit with an equalization function according to claim 2, wherein: The battery pack to be tested is composed of the first power supply battery string, the second power supply battery string, the third power supply battery string, and the fourth power supply battery string connected in parallel. The first power supply battery string is composed of battery cells C11, C21, C31, and C41 connected in series. The second power supply battery string is composed of battery cells C12, C22, C32, and C42 connected in series. The third power supply battery string is composed of battery cells C13, C23, C33, and C43 connected in series. The fourth power supply battery string is composed of battery cells C14, C24, C34, and C44 connected in series; The power supply selection module includes switches M1, M2, M3, and M4. The gates of the switches M1, M2, M3, and M4 are all connected to the controller MCU. The drains of the switches M1, M2, M3, and M4 are all connected to the power supply path. The sources of the switches M1, M2, M3, and M4 are respectively connected to the positive electrodes of battery cells C41, C42, C43, and C44. The negative electrodes of battery cells C11, C12, C13, and C14 are all grounded.

4. The multi-channel battery voltage detection circuit with a balancing function according to claim 3, characterized in that: The multiplexer module includes selectors PC11, PC12, PC13, PC14, PC21, PC22, PC23, PC24, PC31, PC32, PC33, PC34, PC41, PC42, PC43, PC44. All selectors in the multiplexer module are connected to the controller MCU. The input terminals of selectors PC11, PC12, PC13, PC14 are connected to batteries C11, C12, C13, C14 respectively. The output terminals of selectors PC11, PC12, PC13, PC14 are connected together and connected to the input terminal of the analog front-end sampling chip AFE through a filter capacitor cap1. The input terminals of selectors PC21, PC22, PC23, PC24 are connected to batteries C21, C22, C23, C24 respectively. The output terminals of selectors PC21, PC22, PC23, PC24 are connected together and connected to the input terminal of the analog front-end sampling chip AFE through a filter capacitor cap2. The input terminals of selectors PC31, PC32, PC33, PC34 are connected to batteries C31, C32, C33, C34 respectively. The output terminals of selectors PC31, PC32, PC33, PC34 are connected together and connected to the input terminal of the analog front-end sampling chip AFE through a filter capacitor cap3. The input terminals of selectors PC41, PC42, PC43, PC44 are connected to batteries C41, C42, C43, C44 respectively. The output terminals of selectors PC41, PC42, PC43, PC44 are connected together and connected to the input terminal of the analog front-end sampling chip AFE through a filter capacitor cap4.

5. The multi-channel battery voltage detection circuit with a balancing function according to claim 4, wherein: Each selector in the multiplexer module has four channels. When the selector receives the external signal 00 sent by the controller MCU, it selects the first channel. When the selector receives the external signal 01 sent by the controller MCU, it selects the second channel. When the selector receives the external signal 10 sent by the controller MCU, it selects the third channel. When the selector receives the external signal 11 sent by the controller MCU, it selects the fourth channel.

6. The multi-channel battery voltage detection circuit with a balancing function according to claim 2, wherein: Communication between the analog front-end sampling chip AFE and the controller MCU is selected through the SPI or CAN protocol according to the working characteristics. The controller MCU receives the battery voltage signal sent by the analog front-end sampling chip AFE and performs arithmetic processing to detect the battery voltage.

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