CN104201735A - Small electric vehicle power battery pack monitoring and equalization device - Google Patents

Abstract

The invention discloses a power battery pack monitoring and balancing device for a small electric vehicle. The device comprises an intelligent battery module and a control system, wherein the intelligent battery module comprises a battery string and a battery monitoring and balancing system; the control system comprises an MCU module, an LCD unit, a storage unit and a protection alarm unit. The intelligent battery module can be superimposed in proper order on control system in order to enlarge or reduce driving system's capacity, the intelligent battery module of removable damage, and control system calculates battery state information display and storage according to the information of intelligent battery module conveying, produces the protection action of reporting to the police when necessary. And selecting to cut in or cut out a certain intelligent battery module according to the imbalance degree of the intelligent battery modules, and determining the online or offline balance mode of the intelligent battery modules.

Description

Small electric vehicle power battery pack monitoring and equalization device

technical field

The invention belongs to the application field of power batteries, and in particular relates to the monitoring and balancing technology of power battery packs.

Background technique

Power batteries are widely used in electric vehicles because of their high power and high energy density, which can achieve the best balance between efficiency and environmental impact. However, the limitation that the higher the energy is, the more unstable it is, so that the application of power batteries cannot fully guarantee the safety of operation for the time being. The performance and safety performance of a single battery can basically meet the needs of power applications, but the group application is easy to reduce the capacity of the battery pack, reduce the service life of the battery pack, cause fire, explosion and other safety problems, mainly due to the unbalanced performance of the single batteries Therefore, in the field of power battery applications, multiple batteries must be used in groups to meet capacity and power requirements. Therefore, power battery applications require good balancing and protection technologies to improve and improve the performance of battery packs.

The battery pack monitoring and equalization device is to ensure the safety and advantages of the battery pack in operation, that is, the battery pack monitoring and equalization device can accurately estimate the internal state of the battery by collecting external information of the battery; The battery is quickly balanced to maintain a high consistency between the performance of the battery cells; the battery protection command is generated to prevent possible damage to the battery to maximize the life of the battery pack; the historical information is recorded to facilitate the search for faulty batteries.

Considering the system cost and integration level, most of the battery pack monitoring and balancing devices currently use dedicated battery management chips, such as Linear Technology's LTC6801, LTC6802, LTC6803, LTC6804; O2 Micro's OZ890, OZ8920, OZ8940; TI's BQ76pl536, EM1451 ; Other companies such as AD7280, DS2438, BM3318, BM3328, etc. A monitoring and balancing device based on integrated chips For example: Chinese patent ZL201010162444.7 discloses a battery monitoring and balancing system for electric vehicles, which can accurately monitor voltage, temperature, current and calculate SOC, while monitoring insulation status and fault status, and The energy consumption balance of the battery pack can be judged from the text based on a dedicated battery management chip of Linear Technology; Chinese patent ZL201010140237 discloses a power battery monitoring based on the OZ8920 of the O-Convex company for dual control of lithium battery charging and discharging and equalization system; Chinese patent ZL201110335313 discloses a distributed monitoring and equalization control circuit, which can overcome the two-layer control management system with low linearity of ordinary optocouplers; Chinese patent CN201110098028 discloses an online equalization system for battery packs, which can On-line equalization of voltage, internal resistance and capacity of the battery pack; Chinese patent CN200720059575 discloses an online battery equalizer, which can selectively charge and discharge unbalanced single cells to improve the performance of the online running battery pack.

However, the existing technologies for monitoring and equalizing devices for small electric vehicle power battery packs generally have some imperfections: the monitoring and equalizing devices are only suitable for specific battery packs, and when the battery packs reach the end of their service life, the monitoring and equalizing devices will also Then the historical mission is completed; it is inconvenient to expand the capacity or replace the damaged battery, the structure is complex and the cost is high; only the online equalization method is not ideal.

Contents of the invention

In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a power battery pack monitoring and equalization device applied to small electric vehicles, which can increase or decrease intelligent battery modules through port settings, that is, change the capacity application Vehicles with different power requirements; the intelligent battery module can be replaced to increase the service life of the control system; the online and offline equalization methods can be selected according to the unbalanced degree of the intelligent battery module, and the offline equalized method can be used to remedy the unbalanced degree exceeding Smart battery module with maximum threshold.

The object of the present invention is achieved by the following means.

A small electric vehicle power battery pack monitoring and balancing device, comprising a control system 100 and at least two intelligent battery modules: the first intelligent battery module 200 and the second intelligent battery module (300); the control system 100 and the second intelligent battery module (300); The first intelligent battery module 200 is connected, and all the intelligent battery modules (200, 300) are serially connected through the signal bus (230, 330) at the connection port of the battery monitoring and balancing system (220, 320), and the intelligent battery modules The set of serial connections is as follows: the bottom connection port 228 of the first intelligent battery module 200 is connected to the control system 100, the bottom connection port of the second intelligent battery module 300 is connected to the top connection port 229 of the first intelligent battery module 200, And so on. Each bottom connection port is connected with the top connection port to form a serial signal bus (230, 330), and completes the transmission of voltage, current, temperature signals and balance control signals between the smart battery modules; the battery in the smart battery module 200 The string 210 is connected in parallel with the battery string 310 in the smart battery module 300 on the power bus 500 to provide the required power for the vehicle 400 .

The control system 100 in the monitoring and equalizing device of the power battery pack of the small electric vehicle is composed of an MCU module 110, a protection alarm unit 120, a storage unit 130, and an LCD unit 140, wherein the protection alarm unit 120, the storage unit 130, and the LCD unit 140 are respectively It is connected with the MCU module 110 .

The first intelligent battery module 200 includes a battery string 210, a battery monitoring and balancing system 220, and a signal bus 230. The battery string 210 is composed of 12 single cells connected in series. The battery monitoring and balancing system 220 includes a thermistor 221, a voltage Acquisition bus 222, temperature acquisition bus 223, protection switch 224, current sensor 225, voltage monitoring unit 226, setting port 227, bottom connection port 228, top connection port 229, battery string 210 is connected with battery monitoring and balancing system 220, battery The monitoring and balancing system 220 is connected to the control system 100 or the battery monitoring and balancing system 320 is connected to the next intelligent battery module 200 .

A plurality of the second intelligent battery modules can be arranged in parallel.

Thus, the device of the present invention includes an intelligent battery module and a control system. The intelligent battery module includes a battery string and a battery monitoring and balancing system. The battery string is composed of 12 single cells in series. The battery monitoring and balancing system includes a thermistor, a voltage acquisition bus, a temperature acquisition bus, a protection switch, a current sensor, The voltage monitoring unit, the setting port, the bottom connection port, the top connection port, the battery string and the battery monitoring and balancing system are connected, the battery monitoring and balancing system is connected to the control system or the battery monitoring and balancing system is connected to the next intelligent battery module. The thermistor collects 4 channels of temperature information; the voltage monitoring unit collects the voltage of 12 single cells in the battery string, and performs equalization control and undervoltage and overvoltage protection actions according to the voltage of the single cells; the current sensor Collect the current of the smart battery module.

The control system includes MCU module, storage unit, LCD unit, protection and alarm unit. The MCU module receives the voltage information sent by the voltage monitoring unit, receives the temperature information sent by the thermistor, receives the current information sent by the current sensor, and according to the voltage, temperature, current, etc. External electrical information, estimate the battery SOC, and realize a series of protection functions for the battery, decide the allowed and prohibited operations for different battery states, choose the offline or online equalization mode of the intelligent battery module, and send the above information to the Displayed on the LCD unit; the storage unit can record battery usage history, including cycle times, voltage, current, temperature and other information; the protection alarm unit performs undervoltage, overvoltage, overcurrent, overtemperature Wait for protection and alarm.

The smart battery module includes a setting port, a bottom connection port, and a top connection port. The setting port can set the smart module at the bottom, middle and top of the power system. The control system judges the number of smart battery modules through the detection port settings to obtain the total capacity of the power system, and uses formula 1 to estimate the SOC. At the same time, the control system notifies the smart battery module according to the port settings whether it needs to accept the data transmitted from the previous smart battery module and whether to send the data collected by itself to the next smart battery module or to the control system.

$\mathrm{<span\; class="notranslate">\; SOC</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; SOC</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>\frac{{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; t</span>}}\mathrm{<span\; class="notranslate">\; \&eta;Idt</span>}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

SOC-the current state of charge of the battery pack

SOC ₀ - initial state of charge of the battery pack

η – Charge and discharge coulombic efficiency of the battery pack

I- The total operating current of the battery pack

C _N - rated capacity of the battery pack

When it is necessary to increase the capacity, connect the bottom connection port of the newly added intelligent battery module to the top connection port of the original top intelligent battery module, and set the newly added module to the top position, and set the original top intelligent battery module to the top position. is the middle position; when the capacity needs to be reduced, the top intelligent battery module is separated from the power system, and the second top intelligent battery module is set to the top position; when a module is damaged, replace the intelligent battery module through the connection port and Make the corresponding location settings. The control system calculates the unbalanced degree of each smart battery module by monitoring the voltage of the single cells in each smart battery module, and controls the corresponding protection switching switch to determine whether the smart battery module adopts an online or offline balancing method. Offline equalization is not affected by the rapidly changing current during the operation of the vehicle, so the equalization effect is better than online equalization. The equalization circuit can adopt a passive equalization method with simple control and low cost, or an active equalization method with high efficiency.

As an improvement of the present invention applied to the monitoring and equalizing device of a power battery pack of a small electric vehicle: off-line equalization is used as a remedial method for the unbalanced degree of the battery pack exceeding a set maximum threshold. Compared with the power demand of the vehicle, the intelligent battery module should be connected in parallel with one intelligent battery module as a backup intelligent battery module for off-line equalization. The output and backup smart battery modules are cut in, so as to choose the offline or online equalization method. By default, the topmost smart battery module is used as a backup smart battery module. When the system detects that the imbalance of a certain smart battery module exceeds the set maximum threshold, the smart battery module is cut out and used as a backup smart battery module. Offline equalization, cut in the top intelligent battery module, and then monitor the imbalance degree of each intelligent battery module in real time. When the backup intelligent battery When the group imbalance exceeds the maximum threshold, the smart battery module exceeding the maximum threshold is cut out as a backup smart battery module for offline balancing, and the smart battery module that has completed offline balancing is cut in.

As an improvement of the application of the present invention to the monitoring and equalizing device for power battery packs of small electric vehicles: through port settings, intelligent battery modules with different numbers of parallel connections can be monitored and controlled, and can be applied to power systems with different capacities and powers. It is convenient to increase or decrease the number of intelligent battery modules, increase the application range of the monitoring and equalizing device, and facilitate the replacement of faulty intelligent battery modules, avoiding that when a certain intelligent battery module fails, the entire monitoring and equalizing device must also be replaced. The service life of the monitoring and equalizing device is extended.

As an improvement of the present invention applied to the monitoring and balancing device of the power battery pack of small electric vehicles: the protection switching switch in the intelligent battery module can be used as over-current, over-temperature protection, etc., or as an offline and online Toggle switch for equalization mode selection.

Compared with the prior art, the present invention has the following advantages: 1. It can switch between online equalization and offline equalization, and the equalization effect is better; 2. There are preset connection ports between intelligent battery modules, which can be easily expanded The capacity of the power system can also facilitate the replacement of faulty smart battery modules.

Description of drawings:

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings, wherein:

Figure 1 is an overall schematic diagram of the monitoring and equalization device for the power battery pack of a small electric vehicle

FIG. 2 is a detailed schematic diagram of the smart battery module 200 in FIG. 1

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings: It should be understood that the specific embodiments described in detail are only for illustrating the present invention, rather than limiting the protection scope of the present invention.

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

The present invention provides a small electric vehicle power battery pack monitoring and balancing device, including a control system 100 and several intelligent battery modules (200, 300), the control system 100 is connected with the first intelligent battery module 200, and all intelligent battery modules The modules (200, 300) are sequentially connected in series through the signal bus (230, 330) at the connection port of the battery monitoring and balancing system (220, 320), and the serial connection of the several intelligent battery modules is as follows: first The bottom connection port 228 of the smart battery module 200 is connected to the control system 100 , the bottom connection port of the second smart battery module 300 is connected to the top connection port 229 of the first smart battery module 200 , and so on. Each bottom connection port is connected with the top connection port to form a serial signal bus (230, 330), which completes the transmission of voltage, current, temperature signals and balance control signals between intelligent battery modules.

The intelligent battery modules are connected in parallel on the power bus, and the parallel connection of the intelligent battery modules is as follows: the batteries in all the intelligent battery modules are connected in series and parallel on the power bus to provide the required power for the vehicle. As shown in FIG. 1 , the battery string 210 in the smart battery module 200 and the battery string 310 in the smart battery module 300 are connected in parallel on the power bus 500 to provide the required power for the vehicle 400 .

The control system 100 in the monitoring and equalizing device of the power battery pack of the small electric vehicle is composed of an MCU module 110, a protection alarm unit 120, a storage unit 130, and an LCD unit 140, wherein the protection alarm unit 120, the storage unit 130, and the LCD unit 140 are respectively It is connected with the MCU module 110 .

The smart battery module 200 in the power battery pack monitoring and balancing device for small electric vehicles includes a battery string 210, a battery monitoring and balancing system 220, and a signal bus 230. The battery string 210 is composed of 12 single cells connected in series. The balance system 220 includes a thermistor 221, a voltage acquisition bus 222, a temperature acquisition bus 223, a protection switch 224, a current sensor 225, a voltage monitoring unit 226, a setting port 227, a bottom connection port 228, a top connection port 229, and a battery string 210 It is connected with the battery monitoring and balancing system 220 , and the battery monitoring and balancing system 220 is connected with the control system 100 or the battery monitoring and balancing system 320 is connected with the next intelligent battery module 200 .

The battery monitoring and balancing system 220 in the intelligent battery module 200 collects the current of the battery string, the voltage of 12 single cells, and 4 channels of temperature information, and transmits them to the control system 100 through the signal bus 230 at the connection port, and the control system 100 estimates the remaining power of the power system based on the above information, and determines whether an alarm or protection is required, and whether switching in and out is required for balanced mode switching, and simultaneously displays the information on the LCD unit 140 and stores it in the storage unit 130 .

The protection switching switch 224 is used as a switch for selecting a balanced mode for protection and cut-in and cut-out, and here it is recommended to use a high-current relay. When the intelligent battery module has overvoltage, overcurrent, or overtemperature, disconnect 224 to protect the intelligent battery module. When the online balance cannot meet the balance requirements, disconnect 224 to enable the intelligent battery module to select the offline balance mode, and at the same time turn on the standby mode. The protection switching switch 224 of the intelligent battery module performs online equalization and provides power for the system. For example: in a power system with only two intelligent battery modules, the default intelligent battery module 300 is in the off-line balancing mode, and when the unbalanced degree of the intelligent battery module 200 exceeds the set maximum threshold, its protection switching switch 224 is disconnected to enable The smart battery module 200 enters the offline balancing mode until the unbalanced degree is below the minimum threshold, and at the same time, the protection switching switch of the smart battery module 300 is turned on to perform online balancing and provide the required power for the vehicle.

The alarm and protection refers to setting the temperature, current, and voltage thresholds for reasonably opening the protection in the control system 100 according to the working condition test and the battery characteristics, and comparing it with the corresponding information collected by the battery monitoring and balancing system in real time. When the value is close to the threshold, the alarm will be activated, and when the value exceeds the threshold, the protection switching switch will be disconnected to turn off the output of the intelligent battery module, so that the intelligent battery module can work within the range of not damaging battery performance and protecting user safety.

The smart battery module setting port 227 can be used to set the serial connection position of the smart battery module in the entire power system, and different settings can be made at the bottom, middle and top respectively. The present invention proposes to use a three-terminal switch, and the three terminals can be set to indicate that the intelligent battery module is at the bottom, middle, and top respectively. The control system 100 judges the number of intelligent battery modules in the power system by setting the detection port to obtain the power system The total capacity of each intelligent battery module is notified whether it needs to receive the data transmitted from the previous intelligent battery module and whether to send the data collected by itself to the next intelligent battery module or to the control system, so as to ensure that the control system has full control over all intelligent battery modules. Effective management of battery modules; when a smart battery module is damaged, replace the smart battery module through the connection port and set the corresponding position, such as when the smart battery module to be replaced is located at the top of the power system, replace the smart battery After the module, the port of the new smart battery module should be set to the top position; when the capacity needs to be increased, connect the bottom connection port of the newly added smart battery module to the top connection port of the original top smart battery module, and connect the new The added intelligent battery module is set to the top position, and the original top intelligent battery module is set to the middle position; when the capacity needs to be reduced, the top intelligent battery module is separated from the power system, and the second top intelligent battery module is set to the top Location.

Although some embodiments of the present invention have been illustrated and described, it is clear that the present invention is not limited thereto, and those skilled in the art can understand that these embodiments can be modified without departing from the principle and purpose of the present invention. Variations, modifications, substitutions and variations, the scope of the present invention is defined by the claims and their equivalents.

Claims (4)

1. A small electric vehicle power battery pack monitoring and balancing device, comprising a control system (100) and at least two smart battery modules: a first smart battery module (200) and a second smart battery module (300) ; The control system is connected to the first intelligent battery module, and all the intelligent battery modules (200 and 300) are serially connected through the signal bus (230 and 330) at the connection port on the battery monitoring and balancing system, and the intelligent battery modules are connected in series. The row connections are: the bottom connection port (228) of the first intelligent battery module (200) is connected to the control system (100), the bottom connection port of the second intelligent battery module (300) is connected to the first intelligent battery module (200 ) connected to the top-level connection port (229), and so on; each bottom-level connection port is connected to the top-level connection port to form a serial signal bus (230 and 330), to complete the voltage, current, temperature signal and balance between the smart battery modules transmission of control signals; the battery strings (210) in the smart battery module (200) and the battery strings (310) in the smart battery module (300) are connected in parallel on the power bus (500) to provide the vehicles (400) with Power required. the 2. The small electric vehicle power battery pack monitoring and balancing device according to claim 1, characterized in that the control system (100) in the small electric vehicle power battery pack monitoring and balancing device consists of an MCU module (110) , a protection alarm unit (120), a storage unit (130), and an LCD unit (140), wherein the protection alarm unit (120), the storage unit (130), and the LCD unit (140) are connected to the MCU module (110) respectively. the 3. The small electric vehicle power battery pack monitoring and balancing device according to claim 1, characterized in that the first intelligent battery module (200) includes a battery string (210), a battery monitoring and balancing system (220 ), the signal bus (230), the battery string (210) is composed of 12 single cells connected in series, the battery monitoring and balancing system (220) includes thermistor (221), voltage acquisition bus (222), temperature acquisition bus (223 ), protection switch (224), current sensor (225), voltage monitoring unit (226), setting port (227), bottom connection port (228), top connection port (229), battery string (210) and battery monitoring Connected with the balancing system (220), the battery monitoring and balancing system (220) is connected with the control system (100) or the battery monitoring and balancing system (320) is connected with the next intelligent battery module (200). the 4. The device for monitoring and equalizing the power battery pack of a small electric vehicle according to claim 1, wherein a plurality of the second intelligent battery modules can be arranged in parallel. the