DC charging pile intelligent program-controlled test device and test method thereof

Abstract

The intelligent program-controlled test device for DC charging piles has a control circuit arranged in the box, including a live wire L1 port, a live wire L2 port, a live wire L3 port, a neutral wire N1 port, and a grounding PE port. The live wire L1 port, the live wire L2 port, and the live wire L3 port are sequentially connected through an air switch, a phase sequence protector, a contactor KMDY contact, the input end of the frequency converter, and a control area heat dissipation module, and finally connected to the input end of the transformer; a power switch and a switching power supply A are connected in series on the output end of the transformer, and an instrument power supply module, a PLC, a switching power supply B, and a switching power supply C are connected in parallel on the switching power supply A; the switching power supply A is connected in series with a Hall sensor, the switching power supply B is connected in series with a touch screen, and the switching power supply C is connected in series with a mode conversion module. The present invention meets the wide voltage test requirements of the charging pile, realizes the automatic adjustment of the load resistance of the equipment, realizes the automatic addition and subtraction of the load operation, and improves the work efficiency of the tester.

Description

Technical Field

[0001] The present invention belongs to the technical field of testing DC charging piles for new energy electric vehicles, and in particular relates to an intelligent program-controlled testing device for a DC charging pile and a testing method thereof, which are suitable for factory inspection, load testing and aging testing of DC charging piles (charger modules) for new energy electric vehicles. Background Art

[0002] The charging pile test load box is mainly designed and manufactured for the research and development test, production test, and aging test of DC charging pile (charger module) products. The DC charging pile can simulate the different currents and powers of the charging pile for the electric bus through load testing, and test whether the reliability, stability, and functionality of the product meet the national standards and design requirements.

[0003] Introduction to the main functions of the load box:

[0004] Working principle: The working principle of DC charging pile is to convert AC 380V three-phase electricity into DC voltage to charge the battery pack of the electric bus. Different battery pack specifications determine different charging voltages and charging currents. Therefore, the test of DC charging piles provides a good test platform by simulating test conditions of different voltages and capacities through load boxes. The working principle of the load box is to adjust the resistance value. According to Ohm's law, when the rated test voltage (i.e. the output voltage of the charging pile) remains unchanged, the change of the resistance value can achieve the change of the output current and power of the charging pile: I = U / R (current I = output voltage U / resistance R) P = U 2 / R (power P = voltage U squared divided by resistance);

[0005] Control mode: At present, most load boxes are controlled by manual switch (direct control by circuit breaker or contactor). A load box generally has multiple fixed gears. Different resistance values ​​can be simulated by the combination of different gears, so as to adjust the test current and power (resistors are connected in parallel to adjust the resistance value. The more parallel resistors are connected, the smaller the resistance value is).

[0006] Data display: When the load box is working, the real-time output voltage and test current value of the charging pile can be observed through the equipment panel instrument;

[0007] Cooling method: fan forced cooling. When the load box is working, the resistor tube converts electrical energy into heat energy. Therefore, it is necessary to have a cooling fan blowing on the heating area of ​​the resistor to perform air heat exchange to achieve the effect of heat dissipation.

[0008] Wiring method: The busbar copper bar or terminal is used to connect the positive and negative output busbars of the DC charging pile;

[0009] The following technical defects exist in use: 1) Manual switch control mode, loading value requires manual calculation of how to select the appropriate resistance gear, circuit breaker and other controls are directly switched to high-voltage, there are safety hazards, the number of switches is large, the failure rate is high, and maintenance is inconvenient; 2) Single voltage circuit design, poor equipment compatibility, when the actual test voltage is lower than the rated voltage test, the maximum output power drops significantly; P = U 2 / R (power is proportional to the square of the voltage ratio); for example, for a device with a rated voltage of 800V and 100KW, when the actual access voltage is 400V, the maximum test power is 100 / 4=25KW (the actual test voltage is 1 / 2 of the rated value, and the power is calculated as 1 / 4). Obviously, when a 100KW load box is tested at low voltage, the power will be greatly reduced and cannot meet the low voltage high power test requirements; P=U 2 / R (power and voltage are proportional to the square of the ratio); 3) It cannot meet the networking requirements of equipment, and the degree of automated integrated control is poor; 4) The protection function is not comprehensive; 5) With the traditional design, when the user performs a low-power load test (when the heat dissipation capacity is not very high during the low-power test), the fan always works at the rated high speed, and the noise is very loud, just like when working at full load; 6) During the test, the tester needs to keep an eye on the test equipment and record the data. The traditional load box design is still at the stage where the test data needs to be manually recorded, and the test efficiency is low.

[0010] How to design a charging pile that meets the needs of wide voltage testing, how to realize automatic adjustment of load resistance, how to realize automatic addition and subtraction of load operations, how to improve the work efficiency of testers, and how to automatically record the test data during the test process have become issues that need to be solved urgently. Summary of the invention

[0011] The purpose of the present invention is to solve the above technical problems.

[0012] The intelligent program-controlled test device for a DC charging pile comprises a box body, and legs are arranged at the four corners of the bottom of the box body, and the characteristics are as follows: a touch screen is arranged at the upper part of the front panel of the box body, and a power switch, a local / remote light, a fault alarm light, and an emergency stop switch are arranged on the right side of the touch screen from top to bottom in sequence; the touch screen is connected to the PLC in the box body; heat dissipation ports are arranged at the lower parts of both side surfaces of the box body; air outlets are arranged at the top of the box body; a load positive electrode port, a load negative electrode port, a voltage signal component port, a working power supply port, a remote control port, and a grounding port are arranged at the lower part of the rear end surface of the box body from right to left in sequence; a control circuit is arranged in the box body, the working power supply port is a five-core socket, and the remote control port is a three-core socket; the remote control port is an RS485 communication remote control port; the voltage signal component port consists of a voltage signal U+ port and a voltage signal U- port; the voltage signal U+ port and the voltage signal U- port are on the same vertical plane;

[0013] The control circuit includes a live wire L1 port, a live wire L2 port, a live wire L3 port, a neutral wire N1 port, and a ground PE port. The live wire L1 port, the live wire L2 port, the live wire L3 port, the neutral wire N1 port, and the ground PE port are all connected to the working power supply port. The live wire L1 port, the live wire L2 port, and the live wire L3 port are sequentially connected through an air switch, a phase sequence protector, a contactor KMDY contact, an input end of the inverter, and a control area heat dissipation module, and finally connected to the input end of the transformer. The transformer is a 220V to 24V transformer;

[0014] The output end of the frequency converter is connected to the load heat dissipation module, the fan switch module, and the analog quantity module respectively;

[0015] A phase sequence protection module is provided between the live wire L3 segment and the neutral wire N1 port between the phase sequence protector and the contactor KMDY contact, and the phase sequence protection module is connected in series by the phase sequence protector contact and the contactor KMDY;

[0016] The load heat dissipation module is a fan FAN;

[0017] The control area heat dissipation module includes a fan FAN1 and a fan FAN2, and the fan FAN1 and the fan FAN2 are connected in parallel;

[0018] The output end of the transformer is connected in series with a power switch and a switching power supply A, and the switching power supply A is respectively connected in parallel with an instrument power supply module, a PLC, a switching power supply B, and a switching power supply C; the switching power supply A is connected in series with a Hall sensor, the switching power supply B is connected in series with a touch screen, and the switching power supply C is connected in series with a mode conversion module;

[0019] The mode conversion module is composed of nine groups of relays and contactors. The first group is the KA1000V normally open contact of relay A connected in series with the KA500V normally closed contact and the contactor KM1000V in sequence; the second group is the KA500V normally open contact of relay B connected in series with the KA1000V normally closed contact and the contactor KM500V in sequence; the third group is the KAB1 normally open contact of intermediate relay A connected in series with the contactor KMB11, and the contactor KMB11 is connected in parallel with the contactor KMB12; the fourth group is the KAB2 normally open contact of intermediate relay B connected in series with the contactor KMB13, and the contactor KMB13 is connected in parallel with the contactor KMB14; the fifth group is the KAB3 normally open contact of intermediate relay C connected in series with the contactor KMB4; Contactor KMB15 is connected in series, and contactor KMB16 is connected in parallel to contactor KMB15; the sixth group is the normally open contact KAB4 of intermediate relay D and contactor KMB17 in series, and contactor KMB18 is connected in parallel to contactor KMB17; the seventh group is the normally open contact KAB5 of intermediate relay E and contactor KMB19 in series, and contactor KMB20 is connected in parallel to contactor KMB19; the eighth group is the normally open contact KAB6 of intermediate relay F and contactor KMB21 in series, and contactor KMB22 is connected in parallel to contactor KMB21; the ninth group is the normally open contact KAB7 of intermediate relay G and contactor KMB23 in series, and contactor KMB24 is connected in parallel to contactor KMB23.

[0020] The test method of the intelligent program-controlled test device of a DC charging pile includes a PLC main processor, the PLC main processor is respectively connected with an HMI human-machine interface touch device, a switch signal input module, a frequency converter, an extended remote communication interface, an electrical parameter acquisition module, and a load switching relay group, the load switching relay group is connected with a load element, and the frequency converter is connected with a fan, and is characterized in that it includes the following operating steps:

[0021] A) System startup:

[0022] B) Reset the loading timer;

[0023] C) Start load loading:

[0024] According to the voltage mode set by the touch screen, the dual voltage design is divided into low voltage and high voltage. In load mode, the user can select constant power mode or constant current mode on the touch screen interface, and load the load at the user-preset time and load value;

[0025] D) Start the automatic compensation program and set the load judgment module:

[0026] ① Start the automatic compensation program, the PLC will read the voltage and current values ​​collected by the electrical parameter module in real time and compare them with the user set values ​​until the actual voltage and current value errors are within the set accuracy range, and then end the compensation to achieve high-precision adjustment;

[0027] ② Start the load setting judgment module, which judges whether the load has changed. When the load has changed, the new load setting is loaded and then the load setting judgment module is restarted;

[0028] E) During the entire test process, the system performs system fault detection. If a fault is detected, the fault prompt is activated, the fault alarm sounds, and the fan fault judgment module is entered;

[0029] ①When the fan fails, the fan stops and the system automatically disconnects the load;

[0030] ②When it is determined that the fan has no fault, the system automatically disconnects the load;

[0031] F) During the whole test process, the unloading button judgment module performs detection. When the unloading button is pressed, the system automatically disconnects the load;

[0032] G) When the unload button is not pressed, the load time is counted and the load time judgment module is set.

[0033] ①When the set loading time is greater than 0 and the loading time reaches the set value, the system automatically disconnects the load;

[0034] ② When the set loading time is not greater than 0, enter the unload button to judge the module to re-detect;

[0035] H) When the system detects that the current process is loading, the fan is started, and the PLC adjusts the speed of the fan according to the actual voltage and current values ​​of the electrical parameter acquisition module, that is, the load rate;

[0036] I) After disconnecting the load, the system detects that there is no load at present, automatically starts the fan delay shutdown program, and enters the delay judgment module:

[0037] ①When the delay judgment module determines that the delay time has arrived, the fan stops;

[0038] ② When the delay judgment module determines that the delay time has not expired, re-enter the delay judgment module;

[0039] J) Completed.

[0040] In the step D) ①, the automatic compensation is timed. When the compensation time is reached, the system numerical judgment module determines whether the system error is greater than the set threshold. When the system error is greater than the set threshold, the error load is compensated and the automatic compensation program is restarted.

[0041] The present invention has a reasonable structure, meets the wide voltage test requirements of charging piles, realizes automatic adjustment of load resistance of the equipment, realizes automatic addition and subtraction of load operations, and the test data in the test process can be automatically recorded throughout the whole process, thereby improving the work efficiency of testers. The popularization and application of the present invention has good economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the front view of the present invention.

[0043] Figure 2 It is a right side view of the present invention.

[0044] Figure 3 It is a rear view of the present invention.

[0045] Figure 4 It is a control circuit diagram between the working power supply port and the transformer of the present invention.

[0046] Figure 5 It is a control circuit diagram between the transformer and the switching power supply C of the present invention.

[0047] Figure 6 It is a control circuit diagram of the switching power supply C of the present invention connected with the mode conversion module.

[0048] Figure 7 It is a system structure diagram of the present invention.

[0049] Figure 8 It is a process flow chart of the present invention.

[0050] In the figure: 1. Box; 2. Touch screen; 3. Power switch; 4. Local / remote light; 5. Fault alarm light; 6. Emergency stop switch; 7. Load positive terminal; 8. Load negative terminal; 9. Voltage signal component terminal; 10. Working power terminal; 11. Remote control terminal; 12. Grounding terminal; 13. Air switch; 14. Contactor KMDY contact; 15. Phase sequence protector contact; 16. Transformer. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the accompanying drawings, but this is not intended to limit the present invention.

[0052] The intelligent program-controlled test device for a DC charging pile comprises a box 1, wherein the four corners of the bottom of the box 1 are provided with supporting feet, a touch screen 2 is provided on the upper part of the front panel of the box 1, and a power switch 3, a local / remote light 4, a fault alarm light 5, and an emergency stop switch 6 are provided on the right side of the touch screen 2 from top to bottom; the touch screen 2 is connected to the PLC in the box 1; heat dissipation ports are provided at the lower parts of both sides of the box 1; air outlets are provided at the top of the box 1; a load positive electrode port 7, a load negative electrode port 8, a voltage signal component port 9, a working power supply port 10, a remote control port 11, and a grounding port 12 are provided at the lower part of the rear end surface of the box 1 from right to left; a control circuit is provided in the box 1, the working power supply port 10 is a five-core socket, and the remote control port 11 is a three-core socket; the remote control port 11 is an RS485 communication remote control port; the voltage signal component port 9 is composed of a voltage signal U+ port and a voltage signal U- port; the voltage signal U+ port and the voltage signal U- port are on the same vertical plane;

[0053] The control circuit includes a live wire L1 port, a live wire L2 port, a live wire L3 port, a neutral wire N1 port, and a ground PE port. The live wire L1 port, the live wire L2 port, the live wire L3 port, the neutral wire N1 port, and the ground PE port are all connected to the working power supply port 10. The live wire L1 port, the live wire L2 port, and the live wire L3 port are sequentially connected through an air switch 13, a phase sequence protector, a contactor KMDY contact 14, an input end of the inverter, and a control area heat dissipation module, and finally connected to the input end of a transformer 16. The transformer 16 is a 220V to 24V transformer;

[0054] The output end of the frequency converter is connected to the load heat dissipation module, the fan switch module, and the analog quantity module respectively;

[0055] A phase sequence protection module is provided between the live wire L3 segment and the neutral wire N1 port between the phase sequence protector and the contactor KMDY contact 14, and the phase sequence protection module is connected in series by the phase sequence protector contact 15 and the contactor KMDY;

[0056] The load heat dissipation module is a fan FAN;

[0057] The control area heat dissipation module includes a fan FAN1 and a fan FAN2, and the fan FAN1 and the fan FAN2 are connected in parallel;

[0058] The output end of the transformer 16 is connected in series with a power switch 3 and a switching power supply A, and the switching power supply A is respectively connected in parallel with an instrument power supply module, a PLC, a switching power supply B, and a switching power supply C; the switching power supply A is connected in series with the Hall sensor, the switching power supply B is connected in series with the touch screen 2, and the switching power supply C is connected in series with the mode conversion module;

[0059] The mode conversion module is composed of nine groups of relays and contactors. The first group is the KA1000V normally open contact of relay A connected in series with the KA500V normally closed contact and the contactor KM1000V in sequence; the second group is the KA500V normally open contact of relay B connected in series with the KA1000V normally closed contact and the contactor KM500V in sequence; the third group is the KAB1 normally open contact of intermediate relay A connected in series with the contactor KMB11, and the contactor KMB11 is connected in parallel with the contactor KMB12; the fourth group is the KAB2 normally open contact of intermediate relay B connected in series with the contactor KMB13, and the contactor KMB13 is connected in parallel with the contactor KMB14; the fifth group is the KAB3 normally open contact of intermediate relay C connected in series with the contactor KMB4; Contactor KMB15 is connected in series, and contactor KMB16 is connected in parallel to contactor KMB15; the sixth group is the normally open contact KAB4 of intermediate relay D and contactor KMB17 in series, and contactor KMB18 is connected in parallel to contactor KMB17; the seventh group is the normally open contact KAB5 of intermediate relay E and contactor KMB19 in series, and contactor KMB20 is connected in parallel to contactor KMB19; the eighth group is the normally open contact KAB6 of intermediate relay F and contactor KMB21 in series, and contactor KMB22 is connected in parallel to contactor KMB21; the ninth group is the normally open contact KAB7 of intermediate relay G and contactor KMB23 in series, and contactor KMB24 is connected in parallel to contactor KMB23.

[0060] The test method of the intelligent program-controlled test device of a DC charging pile includes a PLC main processor, the PLC main processor is respectively connected with an HMI human-machine interface touch device, a switch signal input module, a frequency converter, an extended remote communication interface, an electrical parameter acquisition module, and a load switching relay group, the load switching relay group is connected with a load element, and the frequency converter is connected with a fan, and is characterized in that it includes the following operating steps:

[0061] A) System startup:

[0062] B) Reset the loading timer;

[0063] C) Start load loading:

[0064] According to the voltage mode set by the touch screen, the dual voltage design is divided into low voltage and high voltage. In load mode, the user can select constant power mode or constant current mode on the touch screen interface, and load the load at the user-preset time and load value;

[0065] D) Start the automatic compensation program and set the load judgment module:

[0066] ① Start the automatic compensation program, the PLC will read the voltage and current values ​​collected by the electrical parameter module in real time and compare them with the user set values ​​until the actual voltage and current value errors are within the set accuracy range, and then end the compensation to achieve high-precision adjustment;

[0067] ② Start the load setting judgment module, which judges whether the load has changed. When the load has changed, the new load setting is loaded and then the load setting judgment module is restarted;

[0068] E) During the entire test process, the system performs system fault detection. If a fault is detected, the fault prompt is activated, the fault alarm sounds, and the fan fault judgment module is entered;

[0069] ①When the fan fails, the fan stops and the system automatically disconnects the load;

[0070] ②When it is determined that the fan has no fault, the system automatically disconnects the load;

[0071] F) During the whole test process, the unloading button judgment module performs detection. When the unloading button is pressed, the system automatically disconnects the load;

[0072] G) When the unload button is not pressed, the load time is counted and the load time judgment module is set.

[0073] ①When the set loading time is greater than 0 and the loading time reaches the set value, the system automatically disconnects the load;

[0074] ② When the set loading time is not greater than 0, enter the unload button to judge the module to re-detect;

[0075] H) When the system detects that the current process is loading, the fan is started, and the PLC adjusts the speed of the fan according to the actual voltage and current values ​​of the electrical parameter acquisition module, that is, the load rate;

[0076] I) After disconnecting the load, the system detects that there is no load at present, automatically starts the fan delay shutdown program, and enters the delay judgment module:

[0077] ①When the delay judgment module determines that the delay time has arrived, the fan stops;

[0078] ② When the delay judgment module determines that the delay time has not expired, re-enter the delay judgment module;

[0079] J) Complete;

[0080] In the step D) ①, the automatic compensation is timed. When the compensation time is reached, the system numerical judgment module determines whether the system error is greater than the set threshold. When the system error is greater than the set threshold, the error load is compensated and the automatic compensation program is restarted.

[0081] When implemented specifically, the beneficial effects of the present invention are as follows:

[0082] 1) Dual voltage circuit design, the device is equipped with 2 groups of resistor stacks of the same voltage level. The 2 groups of resistor stacks can be connected in series or in parallel according to the test requirements. The series connection can meet the high voltage test, and the parallel connection can meet the low voltage test. The power of the combination of the 2 groups of resistor stacks can reach the maximum power regardless of the series or parallel connection. This design is precisely aimed at the characteristics of the wide voltage output of the DC charging pile, which meets the access and use of a wider test voltage. It also has the output capacity of high current and high power during low voltage testing. The equipment has stronger compatibility. Users can test more specifications of products through one device, and there is no need to purchase different test points for different voltage test points. Why not, one machine can be used for multiple purposes;

[0083] Example: Dual voltage design 800V 100KW:

[0084] Adopting 2 groups of 400V 50KW resistor stack design, 2 groups in series can achieve 800V 100KW test requirements, and 2 groups in parallel can achieve 400V 100KW test requirements;

[0085] From the above examples, it is obvious that the dual voltage design has better compatibility and is more suitable for the wide voltage test requirements of charging piles;

[0086] 2) Touch screen intelligent control: Touch screen control is adopted, which makes human-computer interaction more friendly, and the original interface with numerous manual switch buttons in the control area becomes simple and beautiful;

[0087] 3) Load addition and subtraction operation: In addition to the manual control functions, the touch screen also supports automatic load addition and subtraction. The user only needs to output the test current or power value, and the device will automatically adjust the load resistance to achieve automatic load addition and subtraction operations.

[0088] 4) It can realize constant current or constant power control of the load: that is, when the test voltage changes, the device will automatically identify the current test voltage and automatically adjust to the power value or current value set by the customer; this design greatly improves the overall accuracy of the equipment and improves the user experience. The user no longer needs to convert how much power should be invested at different voltages. All is automatically calculated by the equipment and can be adjusted very accurately to the set value accuracy range (the PLC central processor compares the test current value or power value set by the user with the actual voltage and current sampling value in real time, and adjusts the load gear relay to adjust the resistance value until the voltage and current sampling values ​​and the set values ​​are within the equipment accuracy error range);

[0089] 5) Test time can be set: users can preset the test time, and the system will automatically uninstall after the test and automatically shut down the cooling fan after a delay. During the test, there is no need for testers to stay by the side all the time, which can improve the work efficiency and quality for testers and improve the work efficiency for user companies;

[0090] 6) Update the design of the fan to achieve intelligent frequency conversion control according to the test power or current. This solution achieves low noise operation of the equipment during low-power testing, and the humanized design improves user experience (PLC collects and tracks the current test power or current of the equipment in real time, and controls the inverter output according to the ratio, so that the fan speed changes linearly and synchronously according to the load current and power);

[0091] 7) Multiple system protections: instrument communication / PLC communication / fan failure / overtemperature / reverse polarity / overvoltage / overcurrent comprehensive system protection, all protections are monitored by PLC in real time, when a failure occurs, the load is cut off and an alarm is given;

[0092] The protection function of the equipment is more comprehensive and direct than that of traditional load boxes;

[0093] 8) Automatic data storage and recording: The test data during the test process does not need to be recorded manually, the whole data is automatically recorded, and the data can be exported to Excel form;

[0094] 9) Extended communication capabilities: In addition to local touch screen control, it also provides extended communication ports to achieve remote intelligent control, enriching the test interface of automated integrated testing or the Industry 4.0 platform.

[0095] Embodiment 1. The present invention is an intelligent program-controlled load based on PLC control for DC charging pile load testing. The equipment mainly includes PLC, touch screen, inverter, load element, load switching relay group, electrical parameter acquisition module, fan, input switch quantity (wind pressure signal, emergency stop switch signal, etc.), and remote control interface.

[0096] The main body of the load is composed of a load switching relay group and a load element. Different resistance values ​​can be adjusted by cutting off fixed resistance positions through different relay combinations, thereby changing the current and power values ​​of the test circuit;

[0097] The user inputs the test power value or current value through the touch screen interface, and the touch screen sends the command to the PLC central processor, and after conversion, it drives the load switching relay that should act accordingly to meet the set value;

[0098] After the relay group switches the resistance position, the load is loaded, and the electrical parameter acquisition module sends the actual voltage and current values ​​to the PLC central processor;

[0099] After the PLC central processing receives the actual voltage and current values:

[0100] 1) First compare with the set value of the user's touch screen or the value sent by the remote control interface. If the error requirement is not met, the device automatically adjusts the power and current values ​​until the accuracy is achieved;

[0101] 2) Control the output of the inverter, automatically adjust the number of revolutions of the fan, and realize intelligent frequency conversion control of the fan based on actual power and current;

[0102] The switch input information is mainly used for the status collection of the fan and the temperature switch information. When the equipment has a fan failure or over-temperature failure, the PLC can obtain the fault signal in the first time to protect the equipment. At the same time, the emergency stop switch information can be pressed to the PLC, and the system triggers the emergency stop function.

[0103] The above embodiments are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above descriptions. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A DC charging pile intelligent program-controlled test device, comprising a box (1), wherein four corners of the bottom of the box (1) are provided with supporting feet, characterized in that: The upper part of the front panel of the box (1) is provided with a touch screen (2), and the right side of the touch screen (2) is provided with a power switch (3), a local / remote light (4), a fault alarm light (5), and an emergency stop switch (6) in order from top to bottom; the touch screen (2) is connected to the PLC in the box (1); the lower parts of the two side surfaces of the box (1) are provided with heat dissipation ports; the top of the box (1) is provided with air outlets; the lower part of the rear end surface of the box (1) is provided with a load positive terminal (7), a load negative terminal (8), a voltage A signal component port (9), a working power supply port (10), a remote control port (11), and a grounding port (12); a control circuit is arranged in the box body (1); the working power supply port (10) is a five-core socket, and the remote control port (11) is a three-core socket; the remote control port (11) is an RS485 communication remote control port; the voltage signal component port (9) is composed of a voltage signal U+ port and a voltage signal U- port; the voltage signal U+ port and the voltage signal U- port are on the same vertical plane; The control circuit comprises a live wire L1 port, a live wire L2 port, a live wire L3 port, a neutral wire N1 port, and a grounding PE port. The live wire L1 port, the live wire L2 port, the live wire L3 port, the neutral wire N1 port, and the grounding PE port are all connected to a working power supply port (10). The live wire L1 port, the live wire L2 port, and the live wire L3 port are sequentially connected through an air switch (13), a phase sequence protector, a contactor KMDY contact (14), an input end of a frequency converter, and a control area heat dissipation module, and finally connected to an input end of a transformer (16). The transformer (16) is a 220V to 24V transformer. The output end of the frequency converter is connected to the load heat dissipation module, the fan switch module, and the analog quantity module respectively; A phase sequence protection module is provided between the live wire L3 segment and the neutral wire N1 port between the phase sequence protector and the contactor KMDY contact (14), and the phase sequence protection module is connected in series with the phase sequence protector contact (15) and the contactor KMDY; The load heat dissipation module is a fan FAN; The control area heat dissipation module includes a fan FAN1 and a fan FAN2, and the fan FAN1 and the fan FAN2 are connected in parallel; The output end of the transformer (16) is connected in series with a power switch (3) and a switching power supply A, and the switching power supply A is respectively connected in parallel with an instrument power supply module, a PLC, a switching power supply B, and a switching power supply C; the switching power supply A is connected in series with a Hall sensor, the switching power supply B is connected in series with a touch screen (2), and the switching power supply C is connected in series with a mode conversion module; The mode conversion module is composed of nine groups of relays and contactors. The first group is the KA1000V normally open contact of relay A connected in series with the KA500V normally closed contact and the contactor KM1000V in sequence; the second group is the KA500V normally open contact of relay B connected in series with the KA1000V normally closed contact and the contactor KM500V in sequence; the third group is the KAB1 normally open contact of intermediate relay A connected in series with the contactor KMB11, and the contactor KMB11 is connected in parallel with the contactor KMB12; the fourth group is the KAB2 normally open contact of intermediate relay B connected in series with the contactor KMB13, and the contactor KMB13 is connected in parallel with the contactor KMB14; the fifth group is the KAB3 normally open contact of intermediate relay C connected in series with the contactor KMB4; Contactor KMB15 is connected in series, and contactor KMB16 is connected in parallel to contactor KMB15; the sixth group is the normally open contact KAB4 of intermediate relay D and contactor KMB17 in series, and contactor KMB18 is connected in parallel to contactor KMB17; the seventh group is the normally open contact KAB5 of intermediate relay E and contactor KMB19 in series, and contactor KMB20 is connected in parallel to contactor KMB19; the eighth group is the normally open contact KAB6 of intermediate relay F and contactor KMB21 in series, and contactor KMB22 is connected in parallel to contactor KMB21; the ninth group is the normally open contact KAB7 of intermediate relay G and contactor KMB23 in series, and contactor KMB24 is connected in parallel to contactor KMB23.

2. The test method of the DC charging pile intelligent program-controlled test device is characterized by: The test method of the DC charging pile intelligent program-controlled test device is applied to the DC charging pile intelligent program-controlled test device according to claim 1, and the DC charging pile intelligent program-controlled test device also includes: an HMI human-machine interface touch device, a switch signal input module, an extended remote communication interface, an electrical parameter acquisition module and a load switching relay group, and the PLC is respectively connected to the HMI human-machine interface touch device, the switch signal input module, the inverter, the extended remote communication interface, the electrical parameter acquisition module, and the load switching relay group, the load switching relay group is connected to the load element, and the inverter is connected to the fan; the test method of the DC charging pile intelligent program-controlled test device includes the following operating steps: A) System startup: B) Reset the loading timer; C) Start load loading: According to the voltage mode set on the touch screen, the dual voltage design is divided into low voltage and high voltage. In load mode, the user selects constant power mode or constant current mode on the touch screen interface, and loads at the preset time and load value; D) Start the automatic compensation program and set the load judgment module: ① Start the automatic compensation program, the PLC will read the voltage and current values ​​collected by the electrical parameter module in real time and compare them with the user set values ​​until the actual voltage and current value errors are within the set accuracy range, and then end the compensation to achieve high-precision adjustment; ② Start the load setting judgment module, which judges whether the load has changed. When the load has changed, the new load setting is loaded and then the load setting judgment module is restarted; E) During the entire test process, the system performs system fault detection, detects a fault, activates the fault prompt, the fault alarm sounds, and enters the fan fault judgment module; ①When the fan fails, the fan stops and the system automatically disconnects the load; ②When it is determined that the fan has no fault, the system automatically disconnects the load; F) During the whole test process, the unloading button judgment module performs detection. When the unloading button is pressed, the system automatically disconnects the load; G) When the unload button is not pressed, the load time is entered, and the set load time judgment module is entered. ① When the set load time is greater than 0, the load time reaches the set value, and the system automatically disconnects the load; ② When the set loading time is not greater than 0, enter the unload button to judge the module to re-detect; H) When the system detects that the current process is loading, the fan is started, and the PLC adjusts the speed of the fan according to the actual voltage and current values ​​of the electrical parameter acquisition module, that is, the load rate; I) After disconnecting the load, the system detects that there is no load at present, automatically starts the fan delay shutdown program, and enters the delay judgment module: ① When the delay judgment module determines that the delay time has arrived, the fan stops; ② When the delay judgment module determines that the delay time has not expired, re-enter the delay judgment module; J) Completed.

3. The testing method of the DC charging pile intelligent program-controlled testing device according to claim 2 is characterized in that: In the step D) ①, the automatic compensation is timed. When the compensation time is reached, the system numerical judgment module determines whether the system error is greater than the set threshold. When the system error is greater than the set threshold, the error load is compensated and the automatic compensation program is restarted.

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