WO2020019707A1

WO2020019707A1 - Electric automobile power battery pack external short-circuit electro-hydraulic composite control test platform and method

Info

Publication number: WO2020019707A1
Application number: PCT/CN2019/075796
Authority: WO
Inventors: 陈泽宇; 杨英; 蔡雪; 刘承浩
Original assignee: 东北大学
Priority date: 2018-07-27
Filing date: 2019-02-22
Publication date: 2020-01-30
Also published as: CN108919133A; CN108919133B

Abstract

Provided are an electric automobile power battery pack external short-circuit electro-hydraulic composite control test platform and a method. The test platform comprises a battery connector, Hall sensors (HS1, HS2), a thermocouple, a voltage collection unit, a fixed wiring terminal A1, a floating terminal A2, an electromagnetic relay K, an explosion-proof temperature box (1), an upper computer (2), a controller (3) and a hydraulic control system (4), wherein a battery pack short-circuit experiment is controlled by realizing the engagement and separation of the two wiring terminals A1 and A2 by means of the hydraulic control system (4); and a battery cell short-circuit experiment is realized by controlling the closing of the electromagnetic relay K by means of the controller (3). According to the invention, a short-circuit experiment function of a battery pack can be realized, and a short-circuit experiment of any one single battery can also be realized; and the operation mode is flexible and simple, potential risks, such as a fire hazard, of the short-circuit experiment can be efficiently prevented; and a flexible and safe experimental operation can be realized.

Description

External short-circuit electro-hydraulic composite control test bench and method for electric vehicle power battery pack

Technical field

The invention relates to the technical field of electric vehicle power battery safety, in particular to an external short circuit electro-hydraulic composite control test bench and method for an electric vehicle power battery pack.

Background technique

In recent years, due to the increasingly serious problems of environmental pollution and the energy crisis, the development of new energy vehicles with electric vehicles as the core has witnessed rapid development. However, with the gradual commercialization of electric vehicles, electric vehicle accidents due to battery safety have also increased. More and more people have attracted people's attention. Battery safety has become a key link in electric vehicle power battery management technology and a bottleneck that restricts the further development of electric vehicles. There are many manifestations of battery safety issues. High temperature and heat caused by battery damage and external battery failure are one of the main causes of battery fire and explosion. Among them, external short circuit is the most common type of battery failure, and external short circuit will cause power. The battery generates high temperature and large current and then causes serious back ditch, so it is necessary to study the short-circuit characteristics outside the battery.

However, the current research on battery characteristics has focused on battery state estimation, durability management, and capacity enhancement. However, the methods and equipment for battery external short-circuit research are inadequate, and in-depth analysis is focused on battery characteristics in the fault state. Research is also scarce. In order to ascertain the characteristics of the battery in the fault state and further carry out safety management and safety design work, it is inseparable from the experimental analysis of the battery fault, but the current battery test specifications, processes and standardized experimental equipment are also aimed at the normal state Based on the dynamic characteristics of the battery, the external short-circuit fault process of the power battery is short and dangerous. Therefore, how to trigger the external short-circuit fault of the power battery in a comprehensive, safe, and in-depth manner, and record the data of the experimental process of the fault are important. Significant technical issues.

Summary of the Invention

The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art, and to provide an external short circuit electro-hydraulic composite control test bench and method for an external short circuit of an electric vehicle power battery pack, which can realize the short circuit test function of the battery pack, and can also realize any section. The short-circuit experiment of the single battery has flexible and simple operation methods, which can well control the potential danger of fire in the short-circuit experiment and achieve flexible and safe experimental operation.

To solve the above technical problems, the technical solutions adopted by the present invention are:

In one aspect, the present invention provides an external short circuit electro-hydraulic composite control test bench for an electric vehicle power battery pack, which includes a battery connector, a Hall sensor, a thermocouple, a voltage acquisition unit, a fixed terminal A1, a floating terminal A2, and an electromagnetic relay. K, explosion-proof temperature box, host computer, controller and hydraulic control system;

The battery connector is used to connect the single cells to be tested to form a parallel or series structure. The battery connector specifically includes a battery connection strip, a switch K1, and a switch K2. The battery connection strip is used to place the battery to be tested. The positive electrode is located at the upper end of the first battery and is connected to the fixed terminal A1 by a wire. The negative electrode is located at the lower end of the last battery and connected to the floating terminal A2 by a wire. Switches K1 and K2 are used to implement the series and parallel selection of the battery pack. Switch K1 Connected between the positive electrode of the first single cell and the positive electrode of an intermediate single cell, the fixed contact of the switch K2 is connected to the negative electrode of the single previous cell of the intermediate single cell, and the upper contact of the switch K2 The point and the lower contact are respectively connected to the positive electrode of the intermediate unit battery and the negative electrode of the last unit battery. When the switch K1 is closed and the switch K2 is turned to the lower contact, the battery pack is connected in parallel. When the switch K1 When the switch K2 is switched to the upper contact, the battery pack is connected in series.

The thermocouple is attached to the battery and used to read the temperature of the battery to be tested during the experiment. The Hall sensor is connected to the lead wires of the battery poles to read the battery current to be tested during the experiment. The voltage acquisition unit is connected. Between battery positive and negative, used to collect the battery voltage to be tested during the experiment;

The hydraulic control system uses an aqueous medium hydraulic system, including an aqueous medium hydraulic pump PW, a pressure relay D1, a double-acting small hydraulic cylinder D2, and a hydraulic control valve group C; an aqueous medium hydraulic pump PW is used as a power component to connect a water tank; a double-acting small hydraulic cylinder D2 acts as the actuator; the hydraulic control valve group C is used to implement the action control of the double-acting small hydraulic cylinder D2; the pressure relay D1 realizes the conversion of hydraulic signals and electrical signals, and is remotely connected to the controller; a pressure indicator D is connected to the pressure relay D1, Used to display the short-circuit status; hydraulic control valve group C includes an electromagnetic directional valve C1, a one-way valve C2, a sequence valve C3, and an overflow valve C4; the electromagnetic directional valve C1 is an electromagnetically operated two-position four The on-off valve is controlled by the controller and causes the hydraulic circuit to switch. Its outlet A is connected to the rod cavity of the double-acting small hydraulic cylinder D2, and the outlet B is connected to the double-acting small hydraulic cylinder after the parallel structure of the check valve C2 and the sequence valve C3. The rodless cavity of D2, the outlet P and the outlet O are respectively connected to the water medium hydraulic pump PW and the water tank; the check valve C2 only allows the liquid to flow from the hydraulic cylinder to the reversing valve, and prohibits Stop its reverse flow; the hydraulic control port of the sequence valve C3 is connected to the outlet of the water medium hydraulic pump PW; the relief valve C4 is connected between the outlet of the water medium hydraulic pump PW and the water tank;

The setting pressure of the pressure relay D1 is lower than the setting pressure of the sequence valve C3, and the setting pressure of the sequence valve C3 is lower than the setting pressure of the relief valve C4;

The upper computer is placed outside the explosion-proof temperature box and located at the far end, and the controller is placed outside the explosion-proof temperature box and is located at the near end. During the experiment, the power battery pack, battery connector, Hall sensor, thermocouple, were placed in explosion-proof Inside the temperature box; the host computer is used to monitor and send control instructions, the controller is used to receive instructions and trigger short-circuit events, the host computer communicates with the controller through the CAN bus, the controller is connected to the electromagnetic relay, remotely controls the electromagnetic relay K, and sends the instruction to The electromagnetic reversing valve C1 in the hydraulic control system realizes the triggering and termination control of the short-circuit fault through the closing of the electromagnetic relay and the switching of the hydraulic circuit;

On the host computer interface, the user can choose "battery pack short circuit experiment" or "single battery short circuit experiment"; the battery pack short circuit experiment is controlled by the hydraulic control system to achieve the connection and separation of the two connection terminals A1 and A2. The battery The positive lead of the group is wound on the fixed terminal A1 after passing through the explosion-proof temperature box, and the negative lead of the battery pack is wound on the floating terminal A2 after passing through the explosion-proof temperature box. Among them, the fixed terminal A1 is fixed and cannot be moved, and the floating wiring The terminal A2 is connected to the piston rod of the double-acting small hydraulic cylinder D2 and can slide along the guide rail. Under the hydraulic force, the floating terminal A2 moves and comes into contact with the fixed terminal A1 to produce a closed circuit. The short circuit of the battery cell is controlled by the control. It can be realized by controlling the electromagnetic relay K to be closed. The positive and negative poles of the electromagnetic relay K can be freely inserted into any single cell for experiments.

On the other hand, the present invention also provides a control method of the above-mentioned electric vehicle power battery pack external short-circuit electro-hydraulic composite control test bench, which includes the following steps:

S1: Initialize the settings: Initialize the battery capacity, read the sensor data, set the ambient temperature of the explosion-proof temperature box, set the short-circuit duration s ^* on the controller, and select the short-circuited unit on the terminal at the outer end of the battery connector. Body battery number, and make wiring connection, place the test battery together with the battery connector in an explosion-proof temperature box and let it stand for a period of time so that the internal temperature of the battery temperature is consistent and the same as the ambient temperature, proceed to step S2;

S2: Select the test content on the host computer interface. If the battery pack short-circuit test is selected, proceed to step S3; if the battery short-circuit test is selected, proceed to step S6;

S3: Start the water medium hydraulic pump PW to generate high-pressure liquid. After the high-pressure liquid reaches the sequence valve C3, the system does not perform any action due to the blocking of the sequence valve C3. As a result, the pressure continues to rise. As the pressure increases, the pressure relay D1 is Trigger, generate an electric signal to the controller, light the short-circuit status indicator L, and display it on the host computer interface, and then continue to rise with the pressure. When the pressure reaches the opening pressure of the sequence valve C3, the sequence valve C3 is turned on. Push the double-acting small hydraulic cylinder D2 to extend, and then push the floating terminal A2 to be combined with the fixed terminal A1 to connect the positive and negative terminals of the battery pack, and proceed to step S4;

S4: When a short circuit occurs in the battery pack, the current data, voltage data, and temperature data collected by the Hall sensor, voltage acquisition unit, and thermocouple are recorded. When the short-circuit duration t reaches the set time, that is, t≥s ^* , go to step S5;

S5: The controller sends a command to control the electromagnetic directional valve C1 to switch to the right position, the oil circuit is switched, and the high-pressure water flow of the water medium hydraulic pump PW enters the rod cavity of the double-acting small hydraulic cylinder D2, which promotes the double-acting small hydraulic cylinder D2 piston. The rod is retracted, the floating terminal A2 is separated from the fixed terminal A1, and the short circuit process ends. The liquid in the rod cavity of the double-acting small hydraulic cylinder D2 flows out quickly through the one-way valve C2, and the effect of rapid separation is entered; step S7 is performed;

S6: The electromagnetic relay K is controlled remotely by the controller. After the electromagnetic relay K is closed, the selected single cell forms a loop through the electromagnetic relay K, prompting the short circuit of the single cell, recording the Hall sensor, voltage acquisition unit, and thermocouple. The collected current data, voltage data and temperature data; when the short-circuit duration t reaches the set time, that is, t≥s ^* , the controller turns off the electromagnetic relay K and proceeds to step S7;

S7: Record the battery current, voltage and temperature data, and observe and record the battery leakage status.

The beneficial effect produced by adopting the above technical solution lies in: The present invention provides an external short-circuit electro-hydraulic composite control test bench and method for an electric vehicle power battery pack, which can realize the short-circuit test function of the battery pack, and also can realize any single cell. The short circuit experiment of the battery is flexible and simple. The test bench is equipped with a hydraulic hydraulic control system, which is convenient to obtain materials and easy to maintain. At the same time, the flame retardancy of the water can be used to effectively control the potential fire and other dangers of the short circuit experiment. The temperature box can realize flexible and safe experimental operation.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic structural diagram of an external short circuit electro-hydraulic composite control test bench for an electric vehicle power battery pack according to an embodiment of the present invention;

2 is a schematic structural diagram of a battery connector according to an embodiment of the present invention;

3 is a structural connection diagram of a hydraulic control system according to an embodiment of the present invention;

FIG. 4 is a flowchart of an external short circuit experiment of a battery according to an embodiment of the present invention.

In the picture: 1. Explosion-proof temperature box; 2. Host computer; 3. Controller; 4. Hydraulic control system; 5. Wiring plug.

detailed description

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but not to limit the scope of the present invention.

In this embodiment, the model 18650ZD-SV15 lithium-ion power battery is used as an example. Its rated capacity is 2.4Ah, the nominal voltage is 3.6V, the upper cut-off voltage is 4.2V, and the lower cut-off voltage is 2.5V. A total of 20 batteries B1 are used. -B20, divided into 2 groups for external short-circuit characteristic test. The external short-circuit electro-hydraulic composite control test bench for the electric vehicle power battery pack of this embodiment and the control method thereof are as follows.

Electric vehicle power battery pack external short-circuit electro-hydraulic composite control test bench, as shown in Figure 1, includes battery connectors, Hall sensors HS1 and HS2, thermocouple, voltage acquisition unit, fixed terminal A1, floating terminal A2, electromagnetic Relay K, explosion-proof temperature box 1, host computer 2, controller 3, and hydraulic control system 4.

The battery connector is used to connect the single cells to be tested to form a parallel or series structure. The battery connector specifically includes a battery connection strip, a switch K1 and a switch K2, as shown in FIG. 2. The battery terminal strip is used to place the battery to be tested. Its positive electrode is located at the upper end of the first battery and is connected to the fixed terminal A1 by a wire. The negative electrode is located at the lower end of the last battery and connected to the floating terminal A2 by a wire. The plug of the battery connection strip is shown as the connection plug 5 shown in FIG. 2. Switch K1 and switch K2 are used to realize the series and parallel selection of the battery pack. Switch K1 is connected between the positive electrode of the first single cell B1 and the positive electrode of an intermediate single cell B6. The fixed contact of switch K2 is connected to The negative electrode of the previous single cell B5 of the intermediate single cell B6, and the upper and lower contacts of the switch K2 are respectively connected to the positive electrode of the intermediate single cell B6 and the negative of the last single cell B10. When switch K1 is closed and switch K2 is turned to the lower contact, the battery pack is connected in parallel. When switch K1 is turned off and switch K2 is turned to the upper contact, the battery pack is connected in series.

The thermocouple is attached to the battery to read the temperature of the battery to be tested during the experiment. The Hall sensors HS1 and HS2 are connected to the lead wires of the battery poles to read the battery current to be tested during the experiment. The voltage acquisition unit Connected between the positive and negative terminals of the battery to collect the battery voltage to be tested during the experiment. Thermocouples, Hall sensors, and voltage acquisition units use common components.

The hydraulic control system 4 uses an aqueous medium hydraulic system, including an aqueous medium hydraulic pump PW, a pressure relay D1, a double-acting small hydraulic cylinder D2, and a hydraulic control valve group C, as shown in FIG. 3. The water medium hydraulic pump PW is used as the power element to connect the water tank; the double-acting small hydraulic cylinder D2 is used as the actuator, and the hydraulic control valve group C is used to implement the control function; the pressure relay D1 is used to realize the conversion of hydraulic signals and electrical signals, and remotely connected to the controller 3; An indicator light L is also connected to the pressure relay D1, which is used to display the short circuit status. The hydraulic control valve group C is used to realize the action control of the double-acting small hydraulic cylinder D2, including an electromagnetic directional valve C1, a one-way valve C2, a sequence valve C3, and an overflow valve C4; the electromagnetic directional valve C1 is a The solenoid-operated two-position four-way valve is controlled by the controller 3 and causes the hydraulic circuit to switch. Its outlet A is connected to the rod cavity of the double-acting small hydraulic cylinder D2, and the outlet B passes the parallel structure of the check valve C2 and the sequence valve C3. The rodless cavity of the double-acting small hydraulic cylinder D2 is connected to the rear, and the outlet P and the outlet O are respectively connected to the hydraulic pump PW and the water tank W; the check valve C2 is connected in parallel with the sequence valve C3, and one end is connected to the double-acting small hydraulic cylinder D2 The other end is connected to the outlet B of the reversing valve C1. The one-way valve C2 only allows liquid to flow from the hydraulic cylinder to the reversing valve, and prohibits its reverse flow. The pilot port of the sequence valve C3 is connected to The outlet of the water medium hydraulic pump PW; the relief valve C4 is connected between the water medium hydraulic pump PW outlet and the water tank W.

The setting pressure of the pressure relay D1 is lower than the setting pressure of the sequence valve C3, and the setting pressure of the sequence valve C3 is lower than the setting pressure of the relief valve C4.

The upper computer 2 is placed outside the explosion-proof temperature box 1 and located at the far end, and the controller 3 is placed outside the explosion-proof temperature box 1 and located at the near end. During the experiment, the power battery pack, battery connector, Hall sensor, thermocouple, Both are placed inside explosion-proof temperature box 1; host computer 2 is used to monitor and send control instructions, controller 3 is used to receive instructions and trigger short-circuit events, host computer 2 communicates with controller 3 through CAN bus, and controller 3 is connected to electromagnetic relays , Remotely control the electromagnetic relay K, and send a command to the electromagnetic reversing valve C1 in the hydraulic control system 4, through the closing of the electromagnetic relay and the switching of the hydraulic circuit to realize the triggering and termination of the short-circuit fault.

On the interface of host computer 2, the user can choose "battery short circuit experiment" or "single battery short circuit experiment"; the battery short circuit experiment is controlled by the hydraulic control system 4 to achieve the connection and separation of the two connection terminals A1 and A2. The positive lead of the battery pack is wound around the fixed terminal A1 after passing through the explosion-proof temperature box 1, and the negative lead of the battery pack is wound around the floating terminal A2 after passing through the explosion-proof temperature box 1. Among them, the fixed terminal A1 is fixedly installed on the support The floating terminal A2 is connected to the piston rod of the double-acting small hydraulic cylinder D2 and can slide along the guide rail. Under the hydraulic force, the floating terminal A2 moves and contacts the fixed terminal A1 to produce a closed circuit; The body short circuit experiment is realized by the controller 3 controlling the electromagnetic relay K to close. The positive and negative electrodes of the electromagnetic relay K can be freely inserted into any single cell for experiment.

When the test bench works, the hydraulic pump PW is started first. At this time, the directional valve C1 is at the left position. The high-pressure liquid passes through the directional valve C1 and enters the lower end of the check valve C2 and the sequence valve C3. The sequence valve C3 is in the closed state due to the upward flow, so with the operation of the hydraulic pump, the system pressure will gradually rise. When the system pressure is higher than the set pressure of the sequence valve C3, the sequence valve C3 is turned on, and then the liquid can pass through the sequence. Valve C3 enters the hydraulic cylinder D2, the piston rod of the hydraulic cylinder D2 is extended, and the floating terminal A2 is brought closer to the fixed terminal A1. When the floating terminal A2 is in contact with the fixed terminal A1, the battery pack is short-circuited and the The current flows through the terminals A1 and A2. Because the circuit system and the hydraulic control system are two completely separate systems, the large current generated will not have any impact on the control system, which can allow the test bench to withstand a large Short-circuit current. When the short-circuit time exceeds the set time, the controller 3 issues a command to switch the directional valve C1 to the right position. At this time, the hydraulic cylinder is contracted, and the liquid flows back to the water tank W through the check valve C2 and the sequence valve C3. The directional valve allows liquid to flow from top to bottom, so when the liquid returns quickly through the one-way valve, as the piston rod of the hydraulic cylinder retracts, the floating terminal A2 and the fixed terminal A1 are quickly separated, and the short circuit fault of the battery pack is stopped. The experiment is over. The thermocouple sensor attached to the battery, the Hall sensor connected to the wire, and the voltage acquisition unit can read the experimental data such as temperature, current and voltage during the battery experiment.

As shown in FIG. 4, the specific control method of the above-mentioned electric vehicle power battery pack external short-circuit electro-hydraulic composite control test bench is as follows.

Step 1: First perform the initial settings: set the experimental conditions to 50% of the initial battery capacity and 30 degrees Celsius. First initialize the 20 batteries B1-B20 to be tested separately. First, charge and discharge the battery according to the "constant current first and constant voltage" charging method to charge the battery to the full load state, and then use the 0.6A current for 2 hours to discharge Put the battery with a thermocouple on the surface of the battery, Hall sensor HS1 is placed on the electromagnetic relay connection line, Hall sensor HS2 is placed on the positive lead of the battery pack, and batteries B1-B10 are installed on the battery connector to form a battery pack. And placed in the explosion-proof temperature box with the remaining 10 batteries B11-B20, set the thermostat to the temperature to be measured, in this embodiment set to a high temperature of 40 ° C; after debugging the sensor, read the data without error, on the controller Set the short-circuit duration to 30 seconds. After the temperature sensor shows 40 ° C, let it stand for 2 hours to make the temperature inside and outside the battery consistent with the temperature of the incubator. Go to step 2.

Step 2: Select the test content on the host computer interface. If the battery pack short-circuit test is selected, go to step 3. If the battery short-circuit test is selected, go to step 6.

Step 3: Start the hydraulic pump PW to generate high-pressure liquid. After the high-pressure liquid reaches the sequence valve C3, the system does not perform any action because the sequence valve is blocked. As a result, the pressure continues to rise. As the pressure increases, the pressure relay D1 is triggered. Generate an electric signal to the controller, light up the short-circuit status indicator L, and display it on the host computer interface. After that, the pressure continues to rise. When the pressure reaches the opening pressure of the sequence valve C3, the sequence valve C3 is turned on to push the hydraulic pressure. Cylinder D2 is extended, push the floating terminal A2 to the fixed terminal A1, connect the positive and negative terminals of the battery pack, and go to step 4;

Step 4: When a short circuit occurs in the battery pack, record the current data, voltage data, and temperature data collected by the Hall sensor, voltage acquisition unit, and thermocouple. When the short-circuit duration t reaches the set time, that is, t≥30 seconds, go to step 5.

Step 5: The controller sends a command to control the battery reversing valve C1 to switch to the right position, the hydraulic circuit is switched, the high-pressure water flow of the hydraulic pump enters the rod cavity of the hydraulic cylinder D2, and causes the piston rod of the hydraulic cylinder D2 to contract, and the floating terminal A2 Separated from the fixed terminal A1, the short-circuit process ends, the liquid in the rod cavity of the hydraulic cylinder D2 flows out quickly through the check valve C2, and the effect of rapid separation is entered; step 7;

Step 6: Install the batteries B11-B20 to the battery connector. In this embodiment, the single battery B15 is selected for short circuit. The positive and negative terminals of the relay are connected to the positive and negative terminal holes of the B15 battery in the terminal block. The electromagnetic relay is remotely controlled by the controller. After K is closed, after the relay K is closed, the selected single cell forms a loop through the relay K, prompting the short circuit of the single cell, and recording the current data, voltage data, and temperature data collected by the Hall sensor, voltage acquisition unit, and thermocouple; When the short-circuit duration t reaches the set time, that is, t≥30 seconds, the controller turns off the electromagnetic relay K and proceeds to step 7;

Step 7: Record the battery current, voltage and temperature data, and observe and record the battery leakage status. Take out the battery samples after the experiment, and the experiment is over.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than limiting them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still Modifications to the technical solutions described in the foregoing embodiments, or equivalent replacements of some or all of the technical features thereof; and these modifications or replacements do not depart the essence of the corresponding technical solutions from the scope defined by the claims of the present invention.

Claims

An external short circuit electro-hydraulic composite control test bench for an electric vehicle power battery pack, which is characterized by comprising a battery connector, a Hall sensor, a thermocouple, a voltage acquisition unit, a fixed terminal A1, a floating terminal A2, an electromagnetic relay K, Explosion-proof temperature box (1), host computer (2), controller (3) and hydraulic control system (4);

The battery connector is used to connect the single cells to be tested, forming a parallel or series structure;

The thermocouple is attached to the battery and used to read the temperature of the battery to be tested during the experiment. The Hall sensor is connected to the lead wires of the battery poles to read the battery current to be tested during the experiment. The voltage acquisition unit is connected. Between battery positive and negative, used to collect the battery voltage to be tested during the experiment;

The hydraulic control system (4) uses an aqueous medium hydraulic system, including an aqueous medium hydraulic pump PW, a pressure relay D1, a double-acting small hydraulic cylinder D2, and a hydraulic control valve group C; the aqueous medium hydraulic pump PW is used as a power component to connect a water tank; double acting The small hydraulic cylinder D2 is used as the executive mechanism; the hydraulic control valve group C is used to implement the action control of the double-acting small hydraulic cylinder D2; the pressure relay D1 is used to convert the hydraulic signal and the electric signal, and the controller (3) is remotely connected; on the pressure relay D1 Connect an indicator light L for short-circuit status; hydraulic control valve group C includes an electromagnetic directional valve C1, a check valve C2, a sequence valve C3, and an overflow valve C4; the electromagnetic directional valve C1 is a The solenoid-operated two-position four-way valve is controlled by the controller (3) and causes the hydraulic circuit to switch. Its outlet A is connected to the rod cavity of the double-acting small hydraulic cylinder D2, and the outlet B passes the check valve C2 and the sequence valve C3. The parallel structure is connected to the rodless cavity of the double-acting small hydraulic cylinder D2, and the outlet P and the outlet O are respectively connected to the hydraulic pump PW and the water tank; the check valve C2 only allows liquid to flow from the hydraulic cylinder to the reversing valve. And reverse flow is prohibited; the hydraulic control port of the sequence valve C3 is connected to the outlet of the water medium hydraulic pump PW; the relief valve C4 is connected between the outlet of the water medium hydraulic pump PW and the water tank;

The setting pressure of the pressure relay D1 is lower than the setting pressure of the sequence valve C3, and the setting pressure of the sequence valve C3 is lower than the setting pressure of the relief valve C4;

The upper computer (2) is placed outside the explosion-proof temperature box (1) and located at the far end, and the controller (3) is placed outside the explosion-proof temperature box (1) and located at the near end. During the experiment, the power battery pack and battery connector The Hall sensor and thermocouple are placed inside the explosion-proof temperature box (1); the upper computer (2) is used to monitor and send control instructions, the controller (3) is used to receive instructions and trigger short-circuit events, and the upper computer (2 ) Communicate with the controller (3) via CAN bus. The controller (3) is connected to the electromagnetic relay, remotely controls the electromagnetic relay K, and sends a command to the electromagnetic reversing valve C1 in the hydraulic control system (4). Switch with the hydraulic circuit to realize the trigger and termination control of short circuit fault;

On the interface of the host computer (2), the user can choose "battery short circuit experiment" or "single battery short circuit experiment"; the battery short circuit experiment is to achieve the connection and separation of the two connection terminals A1 and A2 through the hydraulic control system (4) For control, the positive lead of the battery pack passes through the explosion-proof temperature box (1) and is wound on the fixed terminal A1, and the negative lead of the battery pack passes through the explosion-proof temperature box (1) and is wound on the floating terminal A2, where the fixed The terminal A1 is fixed and cannot be moved, while the floating terminal A2 is connected to the piston rod of the double-acting small hydraulic cylinder D2 and can slide along the guide rail. The floating terminal A2 moves under the hydraulic force and comes into contact with the fixed terminal A1. The closed circuit; the short-circuit experiment of the battery cell is realized by the controller (3) controlling the electromagnetic relay K to close, and the positive and negative electrodes of the electromagnetic relay K can be freely inserted into any single cell for experiment.
The external short-circuit electro-hydraulic composite control test bench for an electric vehicle power battery pack according to claim 1, wherein the battery connector specifically comprises a battery connection strip, a switch K1 and a switch K2; the battery connection strip is used for Place the battery to be tested. The positive electrode is located on the upper end of the first battery and connected to the fixed terminal A1 through a wire. The negative electrode is located on the lower end of the last battery and connected to the floating terminal A2 through a wire. Switches K1 and K2 are used to implement the battery pack. The switch K1 is connected between the positive electrode of the first single cell and the positive electrode of an intermediate single cell, and the fixed contact of the switch K2 is connected to the first single cell. Negative electrode, the upper and lower contacts of switch K2 are connected to the positive electrode of the intermediate cell and the negative electrode of the last single cell respectively. When switch K1 is closed and switch K2 is turned to the lower contact, the battery pack is In parallel connection mode, when switch K1 is turned off and switch K2 is turned to the upper contact, the battery pack is connected in series.
A control method for an external short-circuit electro-hydraulic composite control test stand for an electric vehicle power battery pack according to claim 1, comprising the following steps:

S1: Initialize the settings: Initialize the battery capacity, read the sensor data, set the ambient temperature of the explosion-proof temperature box, set the short-circuit duration s * on the controller, and select the short-circuited unit on the terminal at the outer end of the battery connector. Body battery number, and make wiring connection, place the test battery together with the battery connector in an explosion-proof temperature box and let it stand for a period of time so that the internal temperature of the battery temperature is consistent and the same as the ambient temperature, proceed to step S2;

S2: Select the test content on the host computer interface. If the battery pack short-circuit test is selected, proceed to step S3; if the battery short-circuit test is selected, proceed to step S6;

S3: Start the water medium hydraulic pump PW to generate high-pressure liquid. After the high-pressure liquid reaches the sequence valve C3, the system does not perform any action due to the blocking of the sequence valve C3. As a result, the pressure continues to rise. As the pressure increases, the pressure relay D1 is Trigger, generate an electric signal to the controller, light the short-circuit status indicator L, and display it on the host computer interface, and then continue to rise with the pressure. When the pressure reaches the opening pressure of the sequence valve C3, the sequence valve C3 is turned on. Push the double-acting small hydraulic cylinder D2 to extend, and then push the floating terminal A2 to be combined with the fixed terminal A1 to connect the positive and negative terminals of the battery pack, and proceed to step S4;

S4: When a short circuit occurs in the battery pack, the current data, voltage data, and temperature data collected by the Hall sensor, voltage acquisition unit, and thermocouple are recorded. When the short-circuit duration t reaches the set time, that is, t≥s * , go to step S5;

S5: The controller sends a command to control the electromagnetic directional valve C1 to switch to the right position, the oil circuit is switched, and the high-pressure water flow of the water medium hydraulic pump PW enters the rod cavity of the double-acting small hydraulic cylinder D2, which promotes the double-acting small hydraulic cylinder D2 piston. The rod is retracted, the floating terminal A2 is separated from the fixed terminal A1, and the short circuit process ends. The liquid in the rod cavity of the double-acting small hydraulic cylinder D2 flows out quickly through the one-way valve C2, and the effect of rapid separation is entered; step S7 is performed;

S6: The electromagnetic relay K is controlled remotely by the controller. After the electromagnetic relay K is closed, the selected single cell forms a loop through the electromagnetic relay K, prompting the short circuit of the single cell, recording the Hall sensor, voltage acquisition unit, and thermocouple. The collected current data, voltage data and temperature data; when the short-circuit duration t reaches the set time, that is, t≥s * , the controller turns off the electromagnetic relay K and proceeds to step S7;

S7: Record the battery current, voltage and temperature data, and observe and record the battery leakage status.