A portable battery connection harness reliability detection device

Abstract

The utility model discloses a portable battery connection harness reliability detection device, wherein the battery connection harness of the battery pack to be tested is connected through a connector, and then input to a sampler through a low-pass filter; the output voltage of the isolated DC / DC is connected to a single battery in the battery pack to be tested after passing through a switch matrix; the output of the isolated DC / DC is suspended, and the potential is switched to different single battery potentials as the switch matrix switches; the current detector detects and amplifies its output current, and outputs a voltage based on a reference ground to the sampler; the switch matrix can only select the positive and negative two branches of a battery to be turned on as output at a time, or all of them are turned off, and the input of the switch matrix is ​​connected to the output of the isolated DC / DC to receive the charging current. The utility model draws power from the battery pack, does not require external power supply, is portable, and is easy to use; the charging current is large, and even small connection abnormalities can show large voltage changes, and the detection coverage is high; automatic detection, no manual judgment is required, high efficiency, and low error rate.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery management, and in particular relates to a portable battery connection harness reliability detection device. Background Art

[0002] Single battery has small capacity and low voltage at both ends. Practical application systems such as electric vehicles and energy storage power stations require multiple batteries to be connected in series or parallel to form a high-voltage system before they can be used. However, the nonlinearity, consistency differences and safe use range of batteries make the battery management system (BMS) a must-have device for electric vehicles. The most basic function of BMS is to monitor the working status of the battery (battery voltage, current and temperature), predict the state of charge (SOC) of the power battery and the corresponding remaining mileage, and manage the battery to avoid overcharging, over-discharging, overcurrent, overheating and serious voltage imbalance between single batteries, so as to maximize the use of battery storage capacity and cycle life.

[0003] The prerequisite for the normal operation of BMS is that the battery connection harness is reliably connected. If there is a problem with the connection wire, such as broken wire, excessive contact resistance, etc., the detected data will be inaccurate and inconsistent with the actual situation, and then make wrong actions, affecting normal use.

[0004] During the production and installation of the wiring harness, a lot of manual work is required, and it is inevitable that some connections will be unreliable or even broken. Figure 1 As shown in the figure, the Bat4 connection is unreliable, and a relatively large connection impedance appears. The input end of the analog front end AFE is not an ideal high impedance, and there is a leakage current. When the Bat4 connection is unreliable, the VC4 voltage is equal to VB4 minus the synthetic leakage current i B4 The voltage drop across the Bat4 connection resistor, VC5 voltage equals VB5 plus the synthetic leakage current i B4 The voltage drop on the Bat4 connection resistor causes the VC4 and VC5 voltages sampled by the AFE to be too low or too high. B4 The composite leakage current itself is a non-ideal parameter, and its direction and magnitude are difficult to quantify. Moreover, it changes with the environment and time, which brings great difficulties to the analysis.

[0005] Prior art 1: After the wiring harness is installed, a multimeter is used to measure the voltage Vbn of each pair of adjacent terminals on the female connector J1-F on the wiring harness and the voltage VBn between the actual positive and negative electrodes of the battery. If Vbn is equal to VBn, the wiring harness connection is considered normal; if Vbn is not equal to VBn, the connection is considered abnormal.

[0006] Disadvantages of prior art 1:

[0007] 1) The distance between adjacent terminals of the female connector is very small, and it is easy to short-circuit when connecting the multimeter, causing safety accidents;

[0008] 2) The female terminals of the connector are all wrapped in plastic, the jack is very small, and it is difficult to insert the multimeter head, which is inefficient;

[0009] 3) There are many wiring harnesses, and it is difficult to match the terminals on the female connector with the actual nodes of the battery, which can easily lead to errors and misjudgment.

[0010] Existing technology 2: After the wiring harness is installed, it is connected to the BMS and powered on. The battery voltage sampled by the BMS is read by the host computer. If the battery voltage is within the normal range, it means that the battery connection is reliable. If the battery voltage exceeds the normal range, it means that the wiring harness connection is unreliable.

[0011] Disadvantages of prior art 2:

[0012] 1) For large battery systems, the BMS is distributed and consists of slave control, master control, master control, LCD screen and other components. It is inconvenient to make the BMS work and then read the voltage data, and it is impossible to find problems in each battery box in time;

[0013] 2) The battery voltage itself has a range, and the AFE leakage current is small, and the voltage drop generated on the contact resistance is small, that is, the VC voltage change seen by the AFE is small. It can only be judged in extreme abnormalities such as disconnection. When the contact resistance is not particularly large, it is easy to miss the judgment;

[0014] The prior art also has the following common shortcomings:

[0015] 1) The judgment of battery voltage depends on the operator's experience and carefulness, which is prone to errors. In addition, the workload is large and the efficiency is low if the battery is judged one by one.

[0016] 2) Unreliable wiring harness connection does not necessarily immediately reflect a large line impedance. In most cases, it will only be reflected after a period of use, vibration, or hot and cold shock. In other words, there is a high probability that no abnormality will be detected during the installation process. After the system is installed and used for a period of time, the problem will be discovered. The cost of disassembling and repairing the machine is high and the efficiency is low;

[0017] 3) During operation, there may be a sudden deterioration of unreliable connection (temperature shock, vibration), causing the system to suddenly shut down due to single cell battery protection, resulting in huge losses. Utility Model Content

[0018] In order to overcome the defects of the prior art, a portable battery connection harness reliability detection device is provided, which includes a battery pack to be tested, a connector, a step-down circuit, a low-pass filter, an MCU, a sampler, an isolated DC / DC, a switch matrix, an isolated power supply, an isolated driver, a current detector, a decoder and a display, wherein:

[0019] The step-down circuit draws power from the total positive and negative voltages of the battery pack under test and supplies power to the MCU after voltage stabilization;

[0020] The battery connection harness of the battery pack under test is connected through a connector and then input into the sampler after passing through a low-pass filter;

[0021] The output of the isolated DC / DC is constant current and voltage limiting, and it takes power from the total positive and negative of the battery pack under test. The output voltage is connected to the single battery in the battery pack under test after passing through the switch matrix; the output of the isolated DC / DC is suspended, and as the switch matrix switches, the potential switches to the potential of different single batteries; the current detector detects and amplifies its output current, and outputs a voltage based on the reference ground to the sampler;

[0022] The switch matrix is ​​composed of n+1 switch branches, where n is the number of battery cells. The switch matrix can only select the positive and negative two branches of a battery cell to be turned on as output at a time, or turn them all off. The input of the switch matrix is ​​connected to the output of the isolated DC / DC to receive the charging current.

[0023] The branch selection of the switch matrix is ​​controlled by an isolation driver, the input of the isolation driver is connected to the output of the decoder, the decoder ensures from the hardware that only one battery can be selected to be connected at a time, and the channel selection of the decoder is controlled by the address given by the MCU;

[0024] The isolated power supply is generated by the auxiliary winding of the isolated DC / DC to provide a suspended power supply for the isolated driver. When the isolated DC / DC is working, the isolated power supply has an output voltage. When the isolated DC / DC is not working, the isolated power supply is automatically turned off and the switch matrix is ​​turned off.

[0025] The sampler samples the battery voltage after the low-pass filter and the output current of the isolated DC / DC, and the MCU communicates with the sampler to obtain the sampling results;

[0026] The MCU displays the voltage of all single batteries, the charging current, and the connection status information of each wiring harness on the display.

[0027] Preferably, the sampler adopts a battery sampling chip or an ADC chip.

[0028] Preferably, the topology of the isolated DC / DC is flyback, forward or push-pull.

[0029] Preferably, the start and stop of the isolated DC / DC is controlled by an IO port of the MCU.

[0030] Preferably, the isolation driver is controlled by a combinational logic of a decoder address.

[0031] Preferably, the isolation driver adopts an optocoupler or a digital isolator or a driving transformer.

[0032] Preferably, the sampler first samples the voltage V of the first battery in the battery pack under test after the MCU starts working. 11 ; MCU controls the switch matrix through the decoder to select the first battery and start the isolated DC / DC to charge the battery; MCU controls the sampler to sample the voltage V of the first battery again 12 and isolated DC / DC output current I1;

[0033] Calculate the impedance of the first battery connection harness:

[0034]

[0035] Determine the status of the first battery connection harness: R1>R ＞ The circuit connection is abnormal, R1<R δ The circuit connection is normal, where R δ It is the set loop resistance judgment threshold.

[0036] Repeat the above judgment until all the circuit connection harnesses of the single battery are detected.

[0037] Preferably, the MCU determines the status of each connection harness:

[0038] If the loop resistance of the mth battery is R m and the m+1th battery loop resistance R m+1 If all connections are normal, then Bat(m-1), Batm, and Bat(m+1) are all normal;

[0039] If the resistance of the mth battery loop is R m Abnormal, the m+1 battery circuit resistance R m+1 Normal, then Bat(m-1) is abnormal, Batm and Bat(m+1) are normal;

[0040] If the resistance of the mth battery loop is R m Normal, the m+1 battery loop resistance R m+1 If it is abnormal, Bat(m-1) and Batm are normal, and Bat(m+1) is abnormal;

[0041] If the resistance of the mth battery loop is R m and the m+1th battery loop resistance R m+1If they are all abnormal, further analysis is performed:

[0042] If R m-1 and R m+2 If both are normal, then the Batm connection line is abnormal, and Bat(m-1) and Bat(m+1) are both normal;

[0043] If R m-1 Also abnormal, but R m+2 If both are normal, then Batm and Bat(m-1) are abnormal, and Bat(m+1) is normal;

[0044] If R m-1 Normal, but R m+2 If it is abnormal, Bat(m-1) is normal, and Batm and Bat(m+1) are both abnormal;

[0045] If R m-1 and R m+2 They are also abnormal, at least 2 connecting harnesses are abnormal;

[0046] Among them, Batm is the mth battery, and so on; 1≤m≤n-1.

[0047] Preferably, the display is a liquid crystal screen, an LED or a digital tube.

[0048] Compared with the prior art, the present invention has at least the following beneficial effects:

[0049] (1) It draws power from the battery pack, does not require external power supply, and is portable and easy to use;

[0050] (2) The charging current is large, and even small connection abnormalities (such as large contact resistance) can show large voltage changes, and the detection coverage is high;

[0051] (3) Automatic detection, no need for manual judgment, high efficiency and low error rate;

[0052] (4) Large current can produce a significant temperature rise at abnormal contact points (large contact resistance), and thermal expansion and contraction can cause hidden problems to emerge;

[0053] (5) It can be checked during the pack installation process without waiting for the entire battery system to be installed and powered on, thus reducing the probability of rework;

[0054] (6) Ability to locate the specific location of wiring harness anomaly. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A schematic diagram of the connection line between the battery and the BMS of the reliability detection device in the prior art;

[0056] Figure 2This is a structural block diagram of a portable battery connection harness reliability detection device according to a specific embodiment of the utility model;

[0057] Figure 3 It is a structural schematic diagram of a portable battery connection harness reliability detection device according to a specific embodiment of the utility model. DETAILED DESCRIPTION

[0058] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0059] See also Figure 2 , 3 The present embodiment discloses a portable battery connection harness reliability detection device, including a battery pack 10 to be tested, a connector 20, a buck circuit 30, a low-pass filter 40, an MCU 50, a sampler 60, an isolated DC / DC 70, a switch matrix 80, an isolated power supply 90, an isolated driver 100, a current detector 110, a decoder 120 and a display 130, wherein:

[0060] The step-down circuit 30 takes power from the total positive and negative voltages of the battery pack 10 under test, and supplies power to the MCU 50 after voltage stabilization; the battery connection harness of the battery pack 10 under test is connected through the connector 20, and then input to the sampler 60 after passing through the low-pass filter 40;

[0061] The output of the isolated DC / DC 70 is a constant current voltage limiter. It takes power from the total positive and negative voltages of the battery pack 10 under test. The output voltage is connected to the single battery in the battery pack 10 under test after passing through the switch matrix 80. The output of the isolated DC / DC 70 is suspended. As the switch matrix 80 switches, the potential switches to the potential of different single batteries. The current detector 110 detects and amplifies its output current, and outputs a voltage based on the reference ground to the sampler 60. The output current of the isolated DC / DC 70 is as large as possible within the safety range of the wiring harness, connector 20, etc., to increase the line resistance voltage drop. At the same time, the large current can cause the contact resistance of each link to rise rapidly, and the thermal expansion and contraction will produce stress, which will stimulate the explicitness of the connection reliability problem.

[0062] The switch matrix 80 is composed of n+1 switch branches, where n is the number of battery cells. The switch matrix 80 can only select the positive and negative branches of a battery cell to be turned on as output at a time, or turn them all off. The input of the switch matrix 80 is connected to the output of the isolated DC / DC 70 to receive the charging current. The branch selection of the switch matrix 80 is controlled by the isolated driver 100. The input of the isolated driver 100 is connected to the output of the decoder 120. The decoder 120 ensures that only one battery cell can be selected to be turned on at a time from the hardware. The channel selection of the decoder 120 is controlled by the address given by the MCU 50.

[0063] The isolated power supply 90 is generated by the auxiliary winding of the isolated DC / DC 70 to provide a floating power supply for the isolated driver 100. When the isolated DC / DC 70 is working, the isolated power supply 90 has an output voltage. When the isolated DC / DC 70 is not working, the isolated power supply 90 is automatically turned off and the switch matrix 80 is turned off. The sampler 60 samples the battery voltage after the low-pass filter 40 and the output current of the isolated DC / DC 70. The MCU 50 communicates with the sampler 60 to obtain its sampling results.

[0064] The MCU 50 coordinates the voltage / current sampling of the sampler 60 , the switching of the switch matrix 80 , the start and stop of the isolated DC / DC 70 , and displays the voltage of all single batteries, the charging current, and the connection status information of each wiring harness on the display 130 .

[0065] The sampler 60 uses a battery sampling chip (i.e., analog front end AFE) or an ADC chip. The topology of the isolated DC / DC 70 is flyback, forward, or push-pull. The start and stop of the isolated DC / DC 70 is controlled by the IO port of the MCU 50 or by the combination logic of the decoder 120 address.

[0066] The isolation driver 100 uses an optocoupler, a digital isolator, or a driving transformer.

[0067] After the MCU 50 starts to work, the sampler 60 first samples the voltage V of the first battery in the battery pack 10 under test. 11 MCU50 controls the switch matrix 80 through the decoder 120 to select the first battery and start the isolated DC / DC 70 to charge the battery; MCU50 controls the sampler 60 to sample the voltage V of the first battery again 12 and isolated DC / DC70 output current I1;

[0068] Calculate the impedance of the first battery connection harness:

[0069]

[0070] Determine the status of the first battery connection harness: R1>R ＞ The circuit connection is abnormal, R1<R δThe circuit connection is normal, where R δ It is the set loop resistance judgment threshold.

[0071] Repeat the above judgment until all the circuit connection harnesses of the single battery are detected.

[0072] MCU50 determines the status of each connection harness:

[0073] If the loop resistance of the mth battery is R m and the m+1th battery loop resistance R m+1 If all connections are normal, then Bat(m-1), Batm, and Bat(m+1) are all normal;

[0074] If the resistance of the mth battery loop is R m Abnormal, the m+1 battery circuit resistance R m+1 Normal, then Bat(m-1) is abnormal, Batm and Bat(m+1) are normal;

[0075] If the resistance of the mth battery loop is R m Normal, the m+1 battery loop resistance R m+1 If it is abnormal, Bat(m-1) and Batm are normal, and Bat(m+1) is abnormal;

[0076] If the resistance of the mth battery loop is R m and the m+1th battery loop resistance R m+1 If they are all abnormal, further analysis is performed:

[0077] If R m-1 and R m+2 If both are normal, then the Batm connection line is abnormal, and Bat(m-1) and Bat(m+1) are both normal;

[0078] If R m-1 Also abnormal, but R m+2 If both are normal, then Batm and Bat(m-1) are abnormal, and Bat(m+1) is normal;

[0079] If R m-1 Normal, but R m+2 If it is abnormal, Bat(m-1) is normal, and Batm and Bat(m+1) are both abnormal;

[0080] If R m-1 and R m+2 They are also abnormal, at least 2 connecting harnesses are abnormal;

[0081] Among them, Batm is the mth battery, and so on; 1≤m≤n-1.

[0082] Finally, the voltage of each battery cell, the charging current of each battery cell and the status of each connection harness are communicated to the display 130 for display.

[0083] In a specific embodiment, the display 130 is a liquid crystal screen or an LED or a digital tube. The isolated power supply 90 driven by the switch matrix 80 can be generated by the isolated DC / DC 70, or can be replaced by an independent isolated power supply 90 module;

[0084] The testing sequence does not necessarily have to start from the first cell of the tested battery pack 10, but may also be reversed, or in other sequences;

[0085] The order of battery voltage sampling and pulse current can be adjusted. For example, first sample the voltage of all single batteries, then pulse current is applied to each battery one by one, and synchronously sample the battery voltage after the pulse current is turned on. After completion, compare the voltage changes of each battery before and after the pulse current is applied.

[0086] The above embodiments are only used to help understand the method and core idea of ​​the utility model. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made to the utility model without departing from the principle of the utility model, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

[0087] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A portable battery connection harness reliability detection device, characterized in that: It includes the tested battery pack, connector, buck circuit, low-pass filter, MCU, sampler, isolated DC / DC, switch matrix, isolated power supply, isolated driver, current detector, decoder and display, among which, The step-down circuit draws power from the total positive and negative voltages of the battery pack under test and supplies power to the MCU after voltage stabilization; The battery connection harness of the battery pack under test is connected through a connector and then input into the sampler after passing through a low-pass filter; The output of the isolated DC / DC is constant current and voltage limiting, and it takes power from the total positive and negative of the battery pack under test. The output voltage is connected to the single battery in the battery pack under test after passing through the switch matrix; the output of the isolated DC / DC is suspended, and as the switch matrix switches, the potential switches to the potential of different single batteries; the current detector detects and amplifies its output current, and outputs a voltage based on the reference ground to the sampler; The switch matrix is ​​composed of n+1 switch branches, where n is the number of battery cells. The switch matrix can only select the positive and negative two branches of a battery cell to be turned on as output at a time, or turn them all off. The input of the switch matrix is ​​connected to the output of the isolated DC / DC to receive the charging current. The branch selection of the switch matrix is ​​controlled by an isolation driver, the input of the isolation driver is connected to the output of the decoder, the decoder ensures from the hardware that only one battery can be selected to be connected at a time, and the channel selection of the decoder is controlled by the address given by the MCU; The isolated power supply is generated by the auxiliary winding of the isolated DC / DC to provide a suspended power supply for the isolated driver. When the isolated DC / DC is working, the isolated power supply has an output voltage. When the isolated DC / DC is not working, the isolated power supply is automatically turned off and the switch matrix is ​​turned off. The sampler samples the battery voltage after the low-pass filter and the output current of the isolated DC / DC, and the MCU communicates with the sampler to obtain the sampling results; The MCU displays the voltage of all single batteries, the charging current, and the connection status information of each wiring harness on the display.

2. The portable battery connection harness reliability detection device according to claim 1, characterized in that: The sampler adopts a battery sampling chip or an ADC chip.

3. The portable battery connection harness reliability detection device according to claim 1, characterized in that: The topology of the isolated DC / DC is flyback, forward or push-pull.

4. The portable battery connection harness reliability detection device according to claim 1, characterized in that: The start and stop of the isolated DC / DC is controlled by the IO port of the MCU.

5. The portable battery connection harness reliability detection device according to claim 1, characterized in that: The isolation driver is controlled by combinational logic of the decoder address.

6. The portable battery connection harness reliability detection device according to claim 1, characterized in that: The isolation driver adopts an optical coupler or a digital isolator or a driving transformer.

7. The portable battery connection harness reliability detection device according to claim 1, characterized in that: The display is a liquid crystal screen, an LED or a digital tube.

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