CN102928789A - Distributed detection method with vibration and temperature and humidity detection for lithium battery pack - Google Patents

Abstract

The invention discloses a distributed detection method for a lithium battery pack with vibration and temperature and humidity detection. The method adopts a group detection method and uses 16 lithium batteries as a group for measurement. Each detection unit includes: a relay gating array, Decoder gating unit, precision reference voltage source circuit, signal conditioning unit, DIP switch, microprocessor MCU, vibration sensor module and temperature and humidity sensor module. The microcontroller MCU of the present invention carries out cyclic detection to the battery cell through the relay gating array, the decoder gating unit, the precision reference voltage source circuit, and the signal conditioning unit, and the information collected by the sensor module and the temperature and humidity sensor module passes through the I ² The C bus and I/O port are sent to the microcontroller MCU respectively, and the detection unit sends the collected lithium battery single-chip voltage information, vibration level information, temperature and humidity information to the lithium battery pack main control unit through the CAN bus. The invention is simple and clear, has high reliability, and can realize high-precision detection of the single-chip voltage signal of the lithium battery, the vibration signal of the battery pack, and the temperature and humidity signals.

Description

A distributed detection method for lithium battery packs with vibration and temperature and humidity detection

technical field

The invention belongs to a distributed detection method for a lithium battery pack, in particular to a distributed detection method for a lithium battery pack with vibration and temperature and humidity detection.

Background technique

Due to its high energy density, long life, low self-discharge rate, and no pollution, lithium batteries have rapidly become a hot spot in the research and development of modern hybrid vehicles. The battery voltage requirements of hybrid power are mostly between 300 and 400V, and some electric vehicles will make the total battery voltage reach more than 500 volts due to the power demand. Generally, the full charge of a single-chip lithium battery is above 3.32V. To achieve a power source of hundreds of volts, more than one hundred lithium batteries need to be connected in series. Due to various internal or external reasons during the operation of the lithium battery system, the lithium battery may be damaged. Abnormal operation of a single chip will affect the performance and safety of the entire lithium battery system. In order to ensure the normal operation of the lithium battery and evaluate its performance, the operating parameters should be monitored in real time. In the process of applying to the hybrid power system, many common factors will affect the work of the lithium battery, such as the vibration of the lithium battery in the car body caused by rough roads, crashes, rollovers, etc., may affect the performance of the battery system; the lithium battery pack is working During the process, a certain temperature gradient will be formed in the battery box due to heat generation. When the temperature is too high, the performance of the battery will be severely degraded, and the battery will even be burned; the presence of moisture in the lithium battery can not only lead to the decomposition of lithium salt in the lithium battery electrolyte And it has a certain corrosion and damage effect on the positive and negative electrode materials and current collectors, and it also leads to a decrease in battery cycle performance and safety performance. Excessive water molecules will also cause battery capacity attenuation. Therefore, the detection of vibration conditions and temperature and humidity information is also a very important part of the detection of lithium batteries.

A distributed detection method for lithium battery packs with vibration and temperature and humidity detection As a new detection method for lithium battery packs, not only the extremely important detection of vibration and temperature and humidity is added to the traditional detection method, but also the detection of voltage Improvements have been made. In the traditional detection method, multiple battery cells are used as a group to form a battery module, and the voltage of the module is measured. Generally, the voltage of the module is about 20 volts (taking five battery cells as an example), and the voltage is relatively high. High, generally needs to be isolated to output to the next level, this method not only cannot know the performance of each single battery (only the performance of the battery module), but also makes the detection unit more complicated.

Contents of the invention

The purpose of the present invention is to provide a simple, reliable, scalable lithium battery pack distributed detection method with vibration and temperature and humidity detection to overcome the shortcomings of the prior art.

In order to achieve the above object, the technical solution adopted in the present invention is:

A distributed detection method for lithium battery packs with vibration and temperature and humidity detection. The method uses n (n<=16) lithium battery cells connected in series as a detection unit for measurement, and each detection unit measures each lithium The battery cell is detected, and it is characterized in that: each detection unit includes: a relay gating array, a decoder gating unit, a precision reference voltage source circuit, a signal conditioning unit, a dial switch, a microprocessor MCU and a vibrating The sensor module and the temperature and humidity sensor module, the detection method of the detection unit is: the microcontroller MCU controls only one relay in the relay array to be gated at any time through the decoder, and the single-chip voltage signal of the gated lithium battery is sent into the The input terminal Vin of the signal conditioning unit performs voltage conditioning, and the output terminal Vout of the signal conditioning unit is converted through the internal A ^/ D module of the microcontroller MCU. Sensors and temperature and humidity sensor information, and send these information to the main control unit of the lithium battery pack through the CAN bus, each detection unit is exactly the same, set an ID number for each detection unit through the dial switch for CAN communication The identifier, so that the main control unit of the lithium battery pack can distinguish which detection unit the information received on the CAN comes from.

The detection unit adopts a self-powered mode, and its power supply is supplied by eight lithium batteries connected in series, and then converted into several required voltage levels by the power module.

Each detection unit measures n=16 lithium battery cells connected in series, and N=m/16 detection units are used when detecting a lithium battery pack composed of m single cells connected in series.

The input terminals of the decoder are respectively controlled by the I/O ports of the microprocessor MCU. When the decoder performs 16 state switches, the output terminals of the decoder are sequentially output as low levels, driving the corresponding relays in the array. The relay switch is closed.

The detection of the single-chip voltage of the lithium battery in each detection unit uses a relay to realize the cyclic detection of the battery cell, and only collects the voltage of a lithium battery at any time. Each detection unit consists of 16 relays to form a relay array. Each battery corresponds to a relay, each relay contains two single relays, the two single relays respectively control the positive and negative poles of the lithium battery, when the relay is gated, the corresponding two single relay switches are closed , connect the positive pole of the single lithium battery to the input terminal of the conditioning unit, and connect the negative pole of the single lithium battery to the ground.

The positive and negative poles of each lithium battery mentioned above are controlled by a relay AQW214EHAZ containing two single relays inside. The microcontroller MCU controls the decoder so that there is only one relay J _i in the relay array at any time (i=1, 2... 16) When strobed, the input terminals A0, A1, A2 and A3 of the decoder are respectively controlled by the I/O port of the microprocessor MCU. When A0, A1, A2 and A3 switch from 0000 to 1111 in 16 states, The output terminals Y0~Y15 of the decoder are sequentially output at low level, the positive pole of the light-emitting diode in the relay is connected to +5V, and the negative pole is connected to the output terminal of the decoder, which is driven by low level, and the output of Y0～Y15 is driven at low level in sequence The switches K (2i-1) and K2i (i=1, 2...32) in the corresponding relay J _i (i=1, 2...16) are closed, so that the negative pole of the gated lithium battery is grounded, and the positive pole is grounded. Connect to the input terminal of the signal conditioning unit. The input terminal signal Vin is connected to the positive input terminal of the operational amplifier U4 in the differential proportional amplification circuit through a voltage follower, and on the other side, the 4.096V voltage output by the +4.096V reference voltage source is connected to the differential proportional amplification circuit through an inverter The negative input terminal of the operational amplifier U4 is used to increase the potential of the input voltage signal in order to measure the negative voltage signal. The output signal Vout of the output terminal of the signal conditioning unit passes through the limiting output protection circuit composed of a capacitor and a voltage regulator tube. It is connected with the internal A/D conversion module of the microcontroller MCU, and the internal A/D conversion module of the MCU provides a precise reference voltage by a +4.096V reference voltage source.

The signal conditioning unit includes a voltage follower composed of a precision rail-to-rail operational amplifier, a voltage inverter, a differential proportional amplifier circuit, precision resistors R1~R6, capacitors C1~C2, and voltage regulator tubes. The input of the single-chip voltage signal terminal is connected to the same-phase terminal of the differential proportional amplifier circuit, and the precision reference voltage source is connected to the inverting terminal of the differential proportional amplifier circuit through a voltage inverter. Its function is to raise the input voltage signal potential, and the output terminal of the signal conditioning unit is set A limiter output protection circuit composed of a capacitor and a voltage regulator tube, the precision reference voltage source used to raise the input voltage signal in the signal conditioning unit is from the reference voltage source used for A/D conversion.

Compared with many modern battery detection systems, the present invention introduces the detection of vibration signals and temperature and humidity signals, which enhances the reliability of battery system applications. In order to achieve the purpose, the acceleration sensor MMA7455L of freescale company is used to collect the vibration signal at first. MMA7455L provides I ² C and SPI digital interface, which enables the microcontroller MCU to connect with the peripheral modules through the main control synchronous serial port. After the micro-control MCU of the detection unit obtains the vibration signal through the I ² C bus, it judges and grades the vibration signal (divided into severe vibration and slight vibration). Secondly, for the collection of temperature and humidity, AM2303 of Aosong Company is used. This is a digital integrated temperature and humidity sensor with high precision and does not require an A/D converter. Send message.

In addition, compared with the traditional detection system, this detection method adopts a self-power supply mode, and does not need a switching power supply to supply power to the detection board. The detection unit uses 24V power supply, and eight lithium batteries are connected in series as the power supply. Then use the power supply module to convert the 24V voltage into various levels of voltage required.

Since there are many detection boards, and each detection board is connected to the CAN network in a similar parallel manner to send the collected information to the main control unit of the lithium battery pack, the main control unit of the lithium battery pack will receive information from each detection board through the CAN network. information collected by the board. In order to enable the main control unit of the lithium battery to distinguish which detection board the information collected on the CAN network comes from, a 5-digit DIP switch is added to each detection board, and each detection board is numbered through the DIP switch. This number is used as The identifier of the detection board during CAN communication. The dialing codes of the dialing switch are sequentially from 00001 to 11111 to mark the 31 fast detection board. When the lithium battery main control unit communicates with CAN, it first judges the CAN network identifier of the sending end (detection board) to clarify which detection board the received signal comes from.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the present invention.

Fig. 2 is a schematic structural diagram of the self-powered power supply module of the detection unit of the present invention.

Fig. 3 is a working flow chart of the detection unit of the present invention.

Detailed ways

The present invention will be further elaborated below in conjunction with the accompanying drawings.

As shown in Figure 1, the detection system can be divided into two parts first: the lithium battery detection unit and the lithium battery main control unit. These two parts are connected through the CAN network. For the lithium battery main control unit.

The self-powered mode is adopted in the detection unit, as shown in Figure 2, eight lithium batteries are connected in series as a power supply, and the single-chip voltage of the phosphate lithium battery is about 3.3V during normal operation, and the range of voltage variation during charging and discharging is The voltage is 3.0V~3.4V, and the voltage of eight lithium batteries connected in series is 24~27.2V, which can be regarded as a power supply of about 24V, and then the power module is used to convert the 24V power supply to the required voltage level. The required voltage levels are plus or minus 12V and +5V, so the 24V to plus or minus 12V power module A2412S-1W and the 24V to +5V power module B2405-2W are used. Considering that the optically isolated power supply in the CAN interface circuit needs to be separated, two 24V to +5V power supply modules are used.

The present invention adopts a distributed detection method, using 16 lithium battery cells as a detection unit for measurement, and the i-th detection unit is for lithium battery cells C _(16t+1) ~ C _(16t+16) (where t= i-1) for detection, the structure of each detection unit is exactly the same, mainly including: relay gating array, decoder gating unit, precision reference voltage source circuit, signal conditioning unit, DIP switch, microprocessor MCU and vibration Sensor module and temperature and humidity sensor module. The only difference is that the ID numbers of each detection unit are different. The dial switches on the detection unit are 00001, 00010, 00011, 00100... to set IDs for detection units 1 to N respectively (N is generally less than 31). By judging the ID number, the lithium battery main control unit can judge which detection unit the data received on the CAN network comes from.

The single lithium battery in each detection unit of the present invention is connected to the output terminals (K1, K2...K32) of the corresponding relay gating array, and the input end of the relay gating array is connected to the output end of the decoder. . The input terminal of the decoder is controlled by the I/O port of the microcontroller MCU. When the input terminals A0, A1, A2, and A3 of the decoder perform 16 state switching from 0000 to 1111, the output terminal Y0～ The output of Y15 in turn is low-level driving corresponding switches K (2i-1) and K2i (i=1, 2...32) in the corresponding relay Ji (i=1, 2...16) are closed, so that the gated lithium The negative electrode of the single battery is grounded and the positive electrode is connected to the input terminal of the signal conditioning unit. Only one output of the decoder is low at any time, which ensures that only a single battery is detected online at any time. The voltage signal of the single-chip battery detected online is sent to the input terminal Vin of the signal conditioning unit for voltage conditioning. A 4.096V reference voltage source is introduced in the signal conditioning unit to raise the potential of the input signal in order to measure the negative voltage caused by the fault. value. The output terminal Vout of the signal conditioning unit is directly connected to the internal A/D module of the microcontroller MCU. The relay is AQW214EHAZ, and each AQW214EHAZ contains two single relays, which respectively control the positive and negative poles of lithium battery cells. Since each detection unit detects 16 battery cells, the selected decoder uses 4 —16-wire decoder 74HC154, the resistors in the signal conditioning unit are precision resistors to ensure the accuracy of the inverter and the proportional differential circuit. Considering that the input voltage of the signal conditioning power supply may exceed 5V, the selected operation The amplifier is a precision operational amplifier chip MAX479 with a power supply voltage greater than 5V. It contains 4 operational amplifiers, which just meet the needs of 4 operational amplifiers in the signal conditioning circuit. The limiter output protection circuit in the signal conditioning unit uses a 5.1V voltage regulator. The tube is enough, because the output of the signal conditioning unit will not exceed 5V. The voltage reference used in the internal A/D module is +4.096V, provided by the precise +4.096V voltage source X60008ES8-41.

The vibration sensor module of the present invention adopts the acceleration sensor MMA7455L of the freescale company to collect vibration signals, and the MMA7455L provides I ² C and SPI digital interfaces, which enables the microcontroller MCU to be connected to the peripheral modules through the main control synchronous serial port. The temperature and humidity sensor module adopts the AM2303 of Aosong Company. This is a digital integrated temperature and humidity sensor with high precision and does not require an A/D converter. It only needs to transmit information to the microcontroller MCU through a simple I/O port. .

The detection unit of the present invention sends the collected voltage signal, vibration signal, and temperature and humidity signal to the main control unit of the lithium battery pack through the CAN network. Before the CAN connection between the detection unit and the main control unit, a CAN interface circuit is required. This interface circuit Includes opto-isolation and CAN transceiver. The optical isolation used in the CAN interface circuit is a high-speed optical isolation 6N137, and the CAN transceiver uses PCA82C250, which is used in the high-speed field of automobiles. This is the most widely used CAN transceiver at present, and supports the ISO-11898 standard. It can be seen from Figure 1 that the microcontroller MCU needs rich I/O ports, with internal A/D converter, I ² C bus, and CAN bus, so the microcontroller MCU in the detection unit uses PIC18F258 from MICROCHIP Company.

The present invention has been described above in conjunction with the best embodiments, but the present invention is not limited to the above-disclosed embodiments, but should cover various modifications and equivalent combinations made according to the essence of the present invention.

Claims (9)

1. lithium battery distribution type detection method with vibration and humiture detection, described method is measured take the lithium battery monomer of n sheet series connection as a detecting unit, each detecting unit detects each lithium battery monomer, it is characterized in that: described each detecting unit comprises: relay gating array, the code translator gating unit, the accurate reference voltage circuit, the signal condition unit, toggle switch, Micro-processor MCV and vibration transducer module and Temperature Humidity Sensor module, the detection method of described detecting unit is: microcontroller only has 1 relay gating by any time in the code translator pilot relay array, the input end Vin that the lithium battery monolithic voltage signal that is strobed is sent into the signal condition unit carries out the voltage conditioning, the output end vo ut of signal condition unit changes by the inner A/D module of microcontroller, and microcontroller passes through respectively I simultaneously ²C bus and I/O mouth obtain the information from vibration transducer and Temperature Humidity Sensor, and these information exchanges are crossed the CAN bus send to lithium battery bag main control unit, described each detecting unit is identical, for each detecting unit an indications that is used for doing the CAN communication for ID number is set by toggle switch, comes from which detecting unit so that lithium battery bag main control unit can be distinguished the upper information of accepting of CAN.

2. as claimed in claim 1 a kind of with the lithium battery distribution type detection method of vibrating and humiture detects, it is characterized in that, detecting unit adopts the self-powered pattern, and its power supply is supplied with by the lithium battery of eight series connection, then utilizes power module to convert several required voltage grades to.

3. as claimed in claim 1 a kind of with the lithium battery distribution type detection method of vibrating and humiture detects, it is characterized in that, each detecting unit is measured the lithium battery monomer of n=16 sheet series connection, when detecting the lithium battery bag of being connected by m sheet monocell, adopts N=m/16 detecting unit.

4. such as claim 1 or 3 described a kind of lithium battery distribution type detection methods with vibration and humiture detection, it is characterized in that, the input end of described code translator is controlled by the I/O mouth of Micro-processor MCV respectively, when code translator carries out 16 kinds of states switchings, the output terminal of code translator is output as low level successively, and it is closed to drive relay switch corresponding in the relay array.

5. as claimed in claim 1 a kind of with the lithium battery distribution type detection method of vibrating and humiture detects, it is characterized in that, detection for lithium battery monolithic voltage in each detecting unit, use relay to realize battery cell is carried out cycle detection, only gather at any time a slice lithium battery voltage, each detecting unit forms a relay array by 16 relays, every corresponding relay of battery monomer, contain two single relays in each relay, two single relays are controlled respectively the both positive and negative polarity of lithium battery monolithic, when relay is strobed, two single relay switches of its correspondence are closed, make respectively the positive pole of lithium battery monolithic connect the conditioning unit input end, the minus earth of lithium battery monolithic.

6. as claimed in claim 1 a kind of with the lithium battery distribution type detection method of vibrating and humiture detects; it is characterized in that; the signal condition unit comprises the voltage follower that accurate rail-to-rail amplifier consists of; voltage inverter and difference ratio amplifying circuit and precision resistance R1～R6; capacitor C 1～C2 and stabilivolt; wherein the input end of monolithic voltage signal is connected with the in-phase end of difference ratio amplifying circuit; accurate reference voltage is connected with the end of oppisite phase of difference ratio amplifying circuit through voltage inverter; its effect is lifting input voltage signal current potential; the output terminal of signal condition unit is provided with the amplitude limit output protection circuit of electric capacity and stabilivolt composition, is used for the accurate reference voltage of lifting input voltage signal in the described signal condition unit from the reference voltage source that is used for the A/D conversion.

7. as claimed in claim 1 a kind of with the lithium battery distribution type detection method of vibrating and humiture detects, it is characterized in that: what the detection of the vibration state that lithium battery occurs in application process was adopted is that the MMA7455L of freescale company realizes that MMA7455L provides I ²C and SPI digital interface.

8. as claimed in claim 7 a kind of with the lithium battery distribution type detection method of vibrating and humiture detects, it is characterized in that, the vibration signal that the detecting unit microcontroller detects vibration transducer MMA7455L is analyzed and classification, when vibration is serious vibration, note vibration indications flag is 1, and when being slight vibration, note vibration indications flag is 0.

9. as claimed in claim 1 a kind of with the lithium battery distribution type detection method of vibrating and humiture detects, it is characterized in that, digital integrated Temperature Humidity Sensor AM2303 is adopted in the detection of lithium battery humiture, and its output signal is digital signal, directly links to each other with the I/O mouth of microcontroller.

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