Battery status diagnostic instrument

Abstract

The present invention provides a battery status diagnostic instrument, which includes a thermostat, a temperature sensor, a fan, a charge and discharge test module and a control module; the temperature sensor is fixed to the thermostat and used to detect the temperature inside the thermostat; the fan is arranged in the thermostat and used to reduce the temperature of the lithium battery to be tested to reach the target temperature; the charge and discharge test module is used to charge or discharge the lithium battery to be tested; the control module is electrically connected to the temperature sensor, the fan and the charge and discharge test module, and is used to control the working state of the fan and the charge and discharge test module, and detect and output the lithium battery status information. By using the battery status diagnostic instrument provided by the present invention to diagnose the battery status, the lithium battery status information can be automatically obtained, and the efficiency and accuracy are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery detection, and in particular to a lithium battery status diagnostic instrument. Background Art

[0002] Lithium batteries are one of the main energy sources for electronic and electrical equipment. There are safety hazards in the application of lithium batteries, and the status of lithium batteries needs to be monitored, estimated or diagnosed. Battery status monitoring is to collect the voltage, current and temperature of the battery in real time during operation, and calculate its state of charge (SOC), health status and operating time based on the battery parameters. Battery status estimation is a method of re-evaluating and revising battery parameters through charge and discharge testing. The above two methods are for measuring batteries with known specifications. If the battery parameters are unknown, the measurement is difficult to carry out. In practical applications, especially in situations where management is not standardized, the parameters of the battery cannot be known. In order to use the battery more safely, it is necessary to diagnose the battery status, that is, to identify the battery status parameters, such as the termination voltage and available power under the charge and discharge state. In this case, to identify the battery status parameters, technicians usually design complex detection processes to carry out charge and discharge tests, and make inferences based on charge and discharge data. The accuracy of the inference depends heavily on the professional level of the technicians. Summary of the invention

[0003] The primary purpose of the present invention is to provide a battery status diagnostic instrument that can automatically complete lithium battery status detection to improve the accuracy of lithium battery status detection.

[0004] Another object of the present invention is to provide a status diagnosis method implemented by the above-mentioned lithium battery status diagnostic instrument.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] As a first aspect, the present invention relates to a battery status diagnostic instrument, which is suitable for testing the status parameters of a lithium battery to be tested, and comprises a constant temperature box, a temperature sensor, a fan, a charge and discharge test module and a control module; the constant temperature box has side panels, a top panel and a bottom panel, and the side panels, the top panel and the bottom panel together define an inner cavity; the temperature sensor is fixed to the constant temperature box and is used to detect the temperature of the lithium battery to be tested; the fan is arranged in the inner cavity and is used to reduce the temperature of the lithium battery to be tested to reach a target temperature; the charge and discharge test module is used to charge or discharge the lithium battery to be tested; the control module is electrically connected to the temperature sensor, the fan and the charge and discharge test module, and is used to control the working status of the fan and the charge and discharge test module, and detect and output lithium battery status information.

[0007] Preferably, the fan is arranged on the inner wall of the side plate of the thermostat.

[0008] Preferably, two fans are provided, which are respectively arranged on a pair of opposite side panels of the thermostat.

[0009] Preferably, the charge and discharge test module comprises a constant current power supply and an electronic load, wherein the constant current power supply is used to be connected to the lithium battery to be tested to charge it, and the electronic load is used to be connected to the lithium battery to be tested to discharge it.

[0010] Preferably, the charge and discharge test module also includes a three-position switch, which includes a fixed pole and an active pole connected to each other, the fixed pole is used to connect to the lithium battery to be tested, and the active pole can be switchably connected to the constant current power supply, the electronic load or be in a suspended state.

[0011] Preferably, the bottom plate of the thermostatic box is provided with a battery placement position; the charge and discharge test module is arranged outside the thermostatic box, and is connected to the lithium battery to be tested at the battery placement position through a wire inserted into the thermostatic box.

[0012] As a second aspect, the present invention also relates to a battery status diagnosis method, which is implemented by the above-mentioned battery status diagnosis instrument, comprising the following steps:

[0013] Put the lithium battery to be tested into the constant temperature box and connect it to the charge and discharge test module;

[0014] The temperature of the lithium battery to be tested is obtained through a temperature sensor, and the working state of the fan is controlled by a control module to make the temperature of the thermostat box at the target temperature;

[0015] The lithium battery to be tested is charged and discharged respectively, the resistance values ​​in the corresponding states are obtained, and the ohmic resistance ratio of the lithium battery to be tested is calculated, where the ohmic resistance ratio is the ratio of the charging ohmic resistance in the charging state to the discharging ohmic resistance in the discharging state;

[0016] Comparing the ohmic resistance ratio with a preset ohmic resistance ratio in a fully charged or fully discharged state to determine a battery charge termination voltage and a battery discharge termination voltage;

[0017] The amount of electricity in the discharge process from the charge termination voltage to the battery discharge termination voltage is recorded as the battery available electricity and the battery status information is displayed.

[0018] Preferably, when a plurality of fans are provided, the control module controls the number of working fans and / or the rotation speed of the fans to control the cooling rate.

[0019] Preferably, in the step of charging and discharging the lithium battery to be tested and obtaining the ohmic resistance ratio, the resistance to be tested is charged and discharged multiple times and alternately to obtain an average charging ohmic resistance in multiple charging states and an average discharging ohmic resistance in multiple discharging states.

[0020] Preferably, when the ohmic resistance ratio is greater than the preset ohmic resistance ratio in the fully charged state, the voltage at this time is the charge termination voltage; when the ohmic resistance ratio is less than the preset ohmic resistance ratio in the fully discharged state, the voltage at this time is the discharge termination voltage, wherein the preset ohmic resistance ratio in the fully charged state is greater than the ohmic resistance ratio in the fully discharged state.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The lithium battery status diagnostic instrument of the present invention realizes the constant ambient temperature during the battery status diagnosis process by setting a constant temperature box, eliminating the measurement error caused by the change of ambient temperature; by monitoring the temperature difference between the battery and the environment during use, the heating condition of the battery is evaluated, the thermal runaway of the battery is avoided, and the accuracy of the detection result is improved. A three-position switch, a controllable constant current power supply and a controllable constant current electronic load are used to switch short-cycle charge and discharge cycles, and the charging and discharging ohmic resistance of the battery under the same state of charge is obtained, and the ohmic resistance ratio that is independent of the battery parameters is obtained to assist in judging whether the battery is tending to be fully charged or fully discharged, thereby marking the battery's charge termination voltage and discharge termination voltage, that is, the voltage range, and finally fully charging and discharging are performed according to the voltage range to obtain the battery's available power. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural block diagram of the lithium battery status diagnostic instrument of the present invention.

[0024] Figure 2 A flowchart of a lithium battery status diagnosis method according to an embodiment of the present invention;

[0025] Figure 3 For the present invention Figure 2 The operating flow chart of the lithium battery status diagnosis method is shown. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and exemplary embodiments, wherein the same reference numerals in the accompanying drawings all refer to the same components. In addition, if the detailed description of known techniques is not necessary for illustrating the features of the present invention, it will be omitted.

[0027] refer to Figure 1 As a first aspect, the present invention relates to a battery status diagnostic instrument (hereinafter referred to as "diagnostic instrument"), which is used to automatically detect and display status parameters of a lithium battery so that a user can intuitively obtain the parameters of the lithium battery and use them reasonably.

[0028] The diagnostic instrument includes a constant temperature box 1, a temperature sensor and a fan 2 arranged in the constant temperature box 1, a charge and discharge test module and a control module 8 arranged outside the constant temperature box 1, and the control module 8 is electrically connected to the temperature sensor, the fan 2 and the charge and discharge test module to control the working state of the fan 2 according to the detection result of the temperature sensor, so that the constant temperature box 1 is at a preset target temperature to ensure the accuracy of the detection result; the charge and discharge module is controlled to charge or discharge the lithium battery to be tested, and the voltage value under the corresponding state is measured, and finally the battery status information such as voltage range, ohmic internal resistance and available power is obtained.

[0029] Among them, preferably, the constant temperature box 1 includes a bottom plate, side plates erected on the edges of the bottom plate, and a top plate connected to one end of the side plate away from the bottom plate, and the bottom plate, the side plate and the top plate jointly define an inner cavity for placing the lithium battery to be tested. Specifically, the bottom plate is provided with a battery placement position, on which positive and negative poles of the battery are provided with positive and negative wires 31 and 32, and the positive and negative wires 31 and 32 pass through the bottom plate of the constant temperature box 1 to facilitate the positioning and installation of the lithium battery to be tested in the inner cavity and the connection of the lithium battery with the control module 8, the temperature sensor and the charge and discharge test module.

[0030] The temperature sensor is arranged outside the thermostat 1, and its probe 4 extends into the thermostat 1 and can be attached to an electrode of the lithium battery to be tested, such as the negative electrode, when in use, to obtain the temperature of the lithium battery.

[0031] There are two fans 2, which are arranged on the inner walls of a pair of opposite side panels, and are used to reduce the temperature of the lithium battery to be tested, accelerate the temperature change in the constant temperature box 1 to reach the target temperature, so as to avoid thermal runaway caused by excessive battery temperature, thereby ensuring the accuracy of the test results.

[0032] The charge and discharge test module includes a constant current power supply 6, an electronic load 7 and a three-position switch 5, and the constant current power supply 6 and the electronic load 7 are electrically connected to the control module 8 and the lithium battery to be tested, so as to charge and discharge the lithium battery to be tested respectively, so as to obtain corresponding parameters in the charging state and the parameters in the discharging state, such as the charging ohmic resistance and the charging termination voltage in the charging state and the discharging ohmic resistance and the discharging termination voltage in the discharging state. It should be understood that the use of the electronic load 7 to discharge the lithium battery to be tested in the present invention does not mean that the electronic load 7 discharges to the lithium battery, but that the lithium battery discharges to the electronic load 7, and the electric energy of the lithium battery is consumed by the electronic load 7. The constant current power supply 6 and the electronic load 7 are both controllable devices, that is, the input and output parameters such as current and voltage are controlled by the control module 8.

[0033] Specifically, the constant current power supply 6 includes a positive output and a negative output, the electronic load 7 includes a positive input and a negative input, and the negative output of the constant current power supply 6 and the negative input of the electronic load 7 are both connected to the negative wire 32. The three-position switch 5 includes a fixed pole and an active pole connected to each other, which is connected to the positive wire 31 to be connected to the lithium battery to be tested through the positive wire 31; its active pole can be switchably connected to the positive output of the constant current power supply 6 and the positive input of the electronic load 7 or be in a suspended state. Thus, the positive output of the constant current power supply 6 can be controlled to be connected to the positive electrode of the lithium battery to be tested through the three-position switch 5, and the negative output is connected to the negative electrode of the lithium battery to be tested, so as to perform constant current charging on the lithium battery to be diagnosed. The positive input of the electronic load 7 is controlled to be connected to the positive electrode of the lithium battery to be tested through the three-position switch 5, and the negative input is connected to the negative electrode of the lithium battery to be tested, so as to perform constant current discharge on the lithium battery to be tested. The suspended state of the active electrode means that the active electrode is located at a third position which is neither connected to the constant current power supply 6 nor to the electronic load 7 .

[0034] The three-position switch 5 is also connected to the control module 8 to controllably switch the connection position of the active pole of the three-position switch 5 to charge, discharge or stop charging and discharging operations of the lithium battery to be tested.

[0035] In a specific embodiment, the control module 8 has measurement, calculation / control and display functions, for example, it may include a sampling unit, a control unit and a display unit which are electrically connected in sequence. The sampling unit is connected to the positive electrode wire 31 and the negative electrode wire 32 to obtain the voltage data of the lithium battery and realize voltage measurement. The control unit is connected to the temperature sensor, the fan 2 and the charge and discharge test module to obtain the detection result of the temperature sensor and control the working state of the fan 2 according to the detection result of the temperature sensor, for example, control the start and stop state and / or speed of the two fans 2, so as to control the cooling rate; control the charge and discharge test module to charge and discharge, specifically control the constant current power supply 6 to charge the battery or control the electronic load 7 to discharge the battery, so as to measure the corresponding voltage values ​​in the charging state and the discharging state, so as to calculate the charging ohmic resistance, the discharging ohmic resistance, and the ohmic resistance ratio, and then compare the ohmic resistance ratio with the preset ohmic resistance ratio, determine the voltage value of the full charge state and the voltage value of the full discharge state, and obtain the voltage range and the available power. The display unit is used to display the battery status information of the lithium battery to be tested, such as the battery internal resistance, the voltage range and the available power. The ohmic resistance ratio is the ratio of the internal resistance of the battery in a charging state (ie, the charging ohmic resistance) to the internal resistance of the battery in a discharging state (ie, the discharging ohmic resistance).

[0036] Please combine Figure 2 and Figure 3As a second aspect, the present invention also provides a state diagnosis method implemented by the above-mentioned lithium battery state diagnosis instrument. The state diagnosis method comprises the following steps:

[0037] S100: Place the lithium battery to be tested into the constant temperature box 1 and connect it to the charge and discharge test module.

[0038] Specifically, the lithium battery to be tested is placed in the battery placement position according to the positive and negative electrodes and the positive electrode wire 31 and the negative electrode wire 32, and the positive electrode wire 31 and the negative electrode wire 32 are correspondingly connected to the positive electrode and the negative electrode of the lithium battery. In addition, the probe 4 of the temperature sensor is attached to the negative electrode of the lithium battery.

[0039] S200: The temperature of the lithium battery to be tested is obtained through a temperature sensor, and the working state of the fan 2 is controlled by the control module 8 to make the temperature of the thermostat 1 at the target temperature.

[0040] In this step, the target temperature of the thermostat 1 is set by the control module 8, and the control module 8 controls the working state of the fan 2 according to the detection result of the temperature sensor to make the temperature in the thermostat 1 the target temperature. For example, when the target temperature is set to 25°, and the sensor detection result is higher than the target temperature, the fan 2 is controlled to rotate to accelerate the temperature change so that it quickly reaches the target temperature value; when the temperature is consistent with the target temperature, the fan 2 is turned off. When there are multiple fans 2, any fan 2 or all fans 2 can be controlled to rotate, or the rotation rate of the fan 2 can be controlled to control the cooling efficiency. In this step, the active pole of the three-position switch 5 is in a suspended state.

[0041] S300: charging and discharging the lithium battery to be tested respectively, obtaining resistance values ​​in corresponding states and calculating an ohmic resistance ratio of the lithium battery to be tested, wherein the ohmic resistance ratio is a ratio of a charging ohmic resistance in a charging state to a discharging ohmic resistance in a discharging state.

[0042] This step specifically includes the following steps:

[0043] S301: First, the user inputs the preset power of the lithium battery Q 0. Energy E 0 or weight W 0, the unit of power is Ah, the unit of energy is Wh, and the unit of weight is kg. The measurement and controller detect that the lithium battery voltage is U 0, in V. The charging current of the constant current power supply 6 and the discharging current of the electronic load 7 are set to the same value, both

[0044]

[0045] S302: Then, the active pole of the three-position switch 5 is connected to the positive output of the constant current power supply 6, and the constant current power supply 6 is controlled to charge the lithium battery. The charging time is 1s, and the voltage before and after charging is recorded, and the absolute value of the voltage difference is calculated, which is recorded as ∆ U c , then calculate the charging ohmic resistance. Specifically, the charging ohmic resistance is calculated as

[0046]

[0047] Then the active pole of the three-position switch 5 is connected to the floating end, and the charging is stopped, which lasts for 5 seconds.

[0048] S303: Then, the active pole of the three-position switch 5 is connected to the positive input of the electronic load 7, and the lithium battery is discharged through the electronic load 7. The discharge time is 1s, and the voltage before and after discharge is recorded, and the absolute value of the voltage difference is calculated and recorded as ∆ U d , the discharge ohmic resistance is calculated as

[0049]

[0050] Then the active pole of the three-position switch 5 is connected to the floating end, and the discharge is stopped, which lasts for 5 seconds.

[0051] S304: In order to improve the accuracy of the detection result, multiple charging and discharging operations may be repeatedly and alternately performed to obtain the average charging ohmic resistance under multiple charging states and the average discharging ohmic resistance under multiple discharging states. For example, a total of six "charge-stop-discharge-stop" cycles are performed, and the average values ​​of the discharging ohmic resistance and the charging ohmic resistance are calculated from the last five cycles, which are respectively

[0052]

[0053] S305: Finally, the ohmic resistance ratio is calculated as

[0054]

[0055] S400: The ohmic resistance ratio k R By comparing with the preset ohmic resistance ratio in the fully charged or fully discharged state, the battery charging termination voltage and the battery discharging termination voltage are determined. Correspondingly, the preset ohmic resistance ratios in the fully charged and fully discharged states are respectively expressed as k c and k d 。

[0056] Specifically, S401: If the ohmic resistance ratio is greater than the full charge preset ohmic resistance ratiok c , it is determined that the battery has reached a fully charged state, and the voltage when charging is stopped in step S302 is used as the battery charging termination voltage. S402: If the ohmic resistance ratio is less than the full discharge preset ohmic resistance ratio k d ( k c > k d ), it is determined that the battery has reached a full discharge state, and the voltage when the discharge is stopped in step S303 is used as the battery discharge termination voltage.

[0057] S403: If the lithium battery is not charged before executing steps S302 to S304, the battery is marked as being in a continuous discharge state, the active pole of the three-position switch 5 is connected to the positive input of the electronic load 7, the electronic load 7 discharges the battery, and the voltage and temperature changes of the battery during the discharge process are measured. If the battery is charged before steps S302 to S304, the battery is marked as being in a continuous charge state, the active pole of the three-position switch 5 is connected to the positive output of the constant current power supply 6, the constant current power supply 6 charges the battery, and the voltage and temperature changes of the battery during the charging process are measured.

[0058] If the temperature change rate ∆ T / ∆ t Greater than the preset upper limit ∆ T max / ∆ t , the charging current of the controllable constant current power supply 6 and the discharging current of the controllable constant current electronic load 7 are both reduced to 0.75 times of the current current to avoid the battery overheating affecting the detection results and even causing thermal runaway problems; if the temperature change rate ∆ T / ∆ t Less than the preset lower limit ∆ T min / ∆ t , the charging current of the controllable constant current power supply 6 and the discharge current of the controllable constant current electronic load 7 are increased to 1.5 times of the current current. If the charging current of the constant current power supply 6 and the discharge current of the electronic load 7 are changed, the charging or discharging is suspended and the fan 2 is started. When the measured value of the temperature sensor is equal to the temperature setting value of the constant temperature box 1, the charging or discharging is continued after the fan 2 is turned off. If the voltage change rate ∆ U / ∆ t (excluding charging or discharging start) greater than the preset upper limit ∆ U max / ∆ t , stop charging or discharging and enter step S300.

[0059] S500: Record the amount of electricity in the discharge process from the charge termination voltage to the battery discharge termination voltage as the available battery electricity and display the battery status information.

[0060] In summary, the present invention uses a constant temperature box 1, a temperature sensor, a fan 2 and a control module 8 to monitor the battery temperature and the ambient temperature changes so that the temperature reaches a preset target temperature, thereby evaluating the heating condition of the battery and avoiding thermal runaway of the battery, thereby improving the accuracy of the detection result.

[0061] In addition, a three-position switch 5, a constant current power supply 6 and an electronic load 7 are used to perform short-cycle charge and discharge cycle switching to obtain the charging ohmic resistance and the discharging ohmic resistance of the battery under the same state of charge, and to obtain an ohmic resistance ratio that is independent of the battery parameters, so as to assist in determining whether the battery is in a fully charged or fully discharged state, thereby marking the battery's charge termination voltage and discharge termination voltage, that is, the voltage range, and finally fully charging and discharging the battery according to the voltage range to obtain the battery's available power. The entire diagnostic process is automatically executed, recorded and calculated by the instrument, and does not rely on the experience of the technician, so the diagnostic efficiency and accuracy are greatly improved.

[0062] Although some exemplary embodiments of the present invention have been shown above, it will be appreciated by those skilled in the art that changes may be made to the exemplary embodiments without departing from the principles or spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery status diagnostic instrument, suitable for testing the status parameters of a lithium battery to be tested, characterized in that: Including constant temperature box, temperature sensor, fan, charge and discharge test module and control module; The thermostatic box has a side plate, a top plate and a bottom plate, and the side plate, the top plate and the bottom plate together define an inner cavity; The temperature sensor is fixed to the thermostat and is used to detect the temperature of the lithium battery to be tested; The fan is arranged in the inner cavity and is used to reduce the temperature of the lithium battery to be tested so that it reaches the target temperature; The charge and discharge test module is used to charge or discharge the lithium battery to be tested; The control module is electrically connected to the temperature sensor, the fan and the charge and discharge test module, and is used to control the working status of the fan and the charge and discharge test module, and detect and output lithium battery status information; The steps of the battery status diagnosis method implemented by the battery status diagnostic instrument are as follows: Put the lithium battery to be tested into the constant temperature box and connect it to the charge and discharge test module; The temperature of the lithium battery to be tested is obtained through a temperature sensor, and the working state of the fan is controlled by a control module to make the temperature of the thermostat box at the target temperature; The lithium battery to be tested is charged and discharged respectively, the resistance values ​​in the corresponding states are obtained, and the ohmic resistance ratio of the lithium battery to be tested is calculated, where the ohmic resistance ratio is the ratio of the charging ohmic resistance in the charging state to the discharging ohmic resistance in the discharging state; Comparing the ohmic resistance ratio with a preset ohmic resistance ratio in a fully charged or fully discharged state to determine a battery charge termination voltage and a battery discharge termination voltage; The amount of electricity in the discharge process from the charge termination voltage to the battery discharge termination voltage is recorded as the available battery electricity and the battery status information is displayed.

2. The battery status diagnostic instrument according to claim 1, characterized in that: The fan is arranged on the inner side wall of the side plate of the thermostatic box.

3. The battery status diagnostic instrument according to claim 2, characterized in that: Two fans are provided and are respectively arranged on a pair of opposite side plates of the thermostatic box.

4. The battery status diagnostic instrument according to claim 1, characterized in that: The charge and discharge test module includes a constant current power supply and an electronic load. The constant current power supply is used to be connected to the lithium battery to be tested to charge it, and the electronic load is used to be connected to the lithium battery to be tested to discharge it.

5. The battery status diagnostic instrument according to claim 4, characterized in that: The charge and discharge test module also includes a three-position switch, which includes a fixed pole and an active pole connected to each other. The fixed pole is used to connect to the lithium battery to be tested, and the active pole can be switchably connected to the constant current power supply, the electronic load or be in a suspended state.

6. The battery status diagnostic instrument according to claim 1, characterized in that: The bottom plate of the thermostatic box is provided with a battery placement position; The charge and discharge test module is arranged outside the thermostatic box and is connected to the lithium battery to be tested at the battery placement position through a wire inserted into the thermostatic box.

7. The battery status diagnostic instrument according to claim 3, characterized in that: When there are multiple fans, the control module controls the number of working fans and / or the speed of the fans to control the cooling rate.

8. The battery status diagnostic instrument according to claim 1, characterized in that: In the step of charging and discharging the lithium battery to be tested and obtaining the ohmic resistance ratio, the resistance to be tested is charged and discharged multiple times and alternately to obtain an average charging ohmic resistance in multiple charging states and an average discharging ohmic resistance in multiple discharging states.

9. The battery status diagnostic instrument according to claim 1, characterized in that: When the ohmic resistance ratio is greater than the preset ohmic resistance ratio in the fully charged state, the voltage at this time is the charge termination voltage; when the ohmic resistance ratio is less than the preset ohmic resistance ratio in the fully discharged state, the voltage at this time is the discharge termination voltage, wherein the preset ohmic resistance ratio in the fully charged state is greater than the ohmic resistance ratio in the fully discharged state.

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