New energy automobile charging safety inspection metering calibration equipment and control method thereof

Abstract

The invention discloses new energy automobile charging safety inspection metering calibration equipment and a control method thereof. The equipment comprises a direct current charging metering calibration module, an insulation resistance calibration module and a potential equalization calibration module, the DC charging metering calibration module comprises a DC charging gun base, a BMS simulator, a high-precision ammeter and a high-precision voltmeter. The insulation resistance calibration module comprises a main control unit, a high-precision resistor, a high-voltage switching unit and an alternating-current charging gun base, the potential equalization calibration module comprises a high-precision galvanometer, a high-precision voltage source and a low-voltage switching unit, and the low-voltage switching unit comprises a low-voltage relay set, a first banana head interface and a second banana head interface. The AC charging gun base is connected to the calibration circuit through the low-voltage relay group. By integrating the high-precision measurement module, the resistance switching unit and the BMS simulator, one-key calibration of direct-current charging, insulation resistance and potential equalization is realized, and the problems of contact resistance interference and multi-instrument collaboration are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of charging piles, and in particular to a new energy vehicle charging safety inspection and calibration device and a control method thereof. Background Art

[0002] With the development of the new energy vehicle annual inspection market, the measurement and calibration of new energy vehicle charging safety inspection equipment has become one of the important links in the development of the industry; because the intelligent new energy vehicle charging safety inspection equipment is connected to the vehicle through the national standard DC charging gun, national standard AC charging gun, resistance test clamp, etc., the traditional calibration methods of charging piles, high resistance meters, and low resistance meters usually have the following defects: 1. Unstable contact resistance: When the resistance test clip is connected to the device, the contact resistance fluctuates greatly, resulting in calibration errors; 2. Inefficient equipment dispersion: multiple independent instruments (such as high resistance meters and low resistance meters) are required, which makes the operation complicated and time-consuming; 3. Lack of intelligence: Unable to automatically switch calibration modes, relying on manual intervention, and low efficiency.

[0003] As a result, the existing traditional calibration methods of charging piles, high resistance meters, and low resistance meters are unable to meet the requirements for efficient and convenient testing of charging safety inspection equipment. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a new energy vehicle charging safety inspection and calibration device and a control method thereof, which overcomes the shortcomings of the prior art and realizes one-click calibration of DC charging, insulation resistance and potential equalization by integrating a high-precision measurement module, a resistance switching unit and a BMS simulator, thereby solving the problems of contact resistance interference and multi-instrument coordination.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A new energy vehicle charging safety inspection and calibration equipment, including a DC charging measurement and calibration module, an insulation resistance calibration module and a potential equalization calibration module; The DC charging metering and calibration module includes a DC charging gun holder, a BMS simulator, a high-precision ammeter and a high-precision voltmeter. The first port of the DC charging gun holder is connected to the DC charging gun of the device under test, and the second port of the DC charging gun holder is connected to the external load box through a load interface; the high-precision ammeter is connected in series in the DC+ path of the DC charging gun holder, and the high-precision voltmeter is connected in parallel between the DC+ and DC- of the DC charging gun holder; the BMS simulator communicates with the device under test through the CAN bus; The insulation resistance calibration module includes a main control unit, a high-precision resistor, a high-voltage switching unit and an AC charging gun holder. The main control unit controls the BMS simulator, the high-precision resistor and the high-voltage switching unit through the CAN bus. The high-voltage switching unit is used to control the high-precision resistor to switch to the DC± terminal and PE terminal of the DC charging gun holder or the L / N terminal and PE terminal of the AC charging gun holder; The potential equalization calibration module includes a high-precision ammeter, a high-precision voltage source and a low-voltage switching unit. The high-precision ammeter is used to measure the calibration loop current, and the high-precision voltage source is used to measure the standard excitation voltage. The low-voltage switching unit includes a low-voltage relay group, a first banana head interface and a second banana head interface. The first banana head interface and the second banana head interface are respectively connected to the positive and negative poles of the resistance test clip of the device under test. The low-voltage relay group is used to connect the resistance test clip of the device under test to the high-precision ammeter and the high-precision voltage source to form an independent current loop and voltage measurement loop, and the PE end of the AC charging gun holder is connected to the calibration circuit through the low-voltage relay group.

[0006] Preferably, the high-voltage switching unit includes a relay K5, a relay K10, a relay K11, a relay K12, a relay K13, a relay K14 and a relay K15, the two ends of the relay K5 are respectively connected to the PE end of the DC charging gun holder and the high-precision resistor, the two ends of the relay K10 are respectively connected to the PE end of the AC charging gun holder and the high-precision resistor, the two ends of the relay K11 are respectively connected to the L / N end of the AC charging gun holder and the high-precision resistor, and the relay K12, the relay K13, the relay K14 and the relay K15 respectively control the high-precision resistor to be connected to the DC± end of the DC charging gun holder; When relay K5, relay K12, relay K13, relay K14 and relay K15 are attracted, the high-precision resistor is connected to the DC± terminal and PE terminal of the DC charging gun holder; When the relay K10 and the relay K11 are attracted, the high-precision resistor is connected to the L / N terminal and the PE terminal of the AC charging gun holder.

[0007] Preferably, the DC+ end of the DC charging gun socket is connected to the DC+ end of the external load box through relay K12 and relay K16, and the DC- end of the DC charging gun socket is connected to the DC- end of the external load box through relay K13 and relay K17.

[0008] Preferably, the low-voltage relay group includes relay K1, relay K2, relay K3, relay K4 and relay K6, relay K7, relay K8, relay K9; When relay K1 and relay K3 are energized, the positive electrode of the high-precision voltage source is connected to the positive electrode of the resistance test clip through the first banana plug interface, forming a positive calibration loop at the PE end of the DC charging gun holder; When reverse current is detected, relays K2 and K4 are energized to switch the circuit polarity; The relay K6, relay K7, relay K8 and relay K9 are used to adapt to the L / N polarity switching of the AC charging gun holder; When relay K6 and relay K8 are energized, the L and PE terminals of the AC charging gun holder are connected to the calibration circuit; When relay K7 and relay K9 are energized, the N terminal and the PE terminal of the AC charging gun holder are connected to the calibration circuit.

[0009] Preferably, the high-precision resistor is a multi-level standard resistor configured according to the 1-2-2-5 principle, and each level of resistance is switched by an independent relay.

[0010] The present invention also discloses a control method for a new energy vehicle charging safety inspection and calibration device, which comprises the following steps: Step S1: Connect the DC charging gun and AC charging gun of the device under inspection to the DC charging gun socket and the AC charging gun socket respectively; Step S2: connecting the positive electrode and the negative electrode of the resistance test clip of the device to be tested to the first banana plug interface and the second banana plug interface respectively; Step S3: DC charging current calibration: energize relays K12 and K13, establish a CAN communication link between the BMS simulator and the device under test, and transmit battery parameters; after entering the charging phase, energize relays K16 and K17, load standard current or voltage to the device under test, and use a high-precision ammeter and a high-precision voltmeter to measure the charging current and voltage, respectively, and compare them with the displayed values ​​of the device under test; Step S4: Current and voltage error calculation: Absolute error: , ; Relative error: ; ; in, is the absolute error of current, is the absolute voltage error; is the current relative error, is the relative voltage error of the equipment under test; is the current value displayed by the device under test, It is the current value displayed by the high-precision ammeter; is the voltage value displayed by the device under test, It is the voltage value displayed by the high-precision voltmeter; Step S5: Insulation resistance calibration: select DC calibration mode or AC calibration mode; When the DC calibration mode is selected, the relay K5 and relays K12, K13, K14 and K15 are energized, and the high-precision resistor is controlled through the CAN bus to cut in the resistance value according to the test requirements, and then the device under test is started, and the insulation resistance value of the device under test is obtained; When the AC calibration mode is in progress, the relay K11 and the relay K10 are energized, and the high-precision resistor is controlled through the CAN bus to cut in the resistance value according to the test requirements, and then the device under test is started, and the insulation resistance value of the device under test is obtained; Step S6: Calculation of resistance value error: Compare the measurement result with the insulation resistance value of the device under test and calculate the error of the device under test: ; ; in, is the absolute error of the resistor, is the relative error of resistance, The insulation resistance value displayed by the device under test. Insulation resistance value displayed for high-precision resistors.

[0011] Step S7: In the potential equalization calibration mode, the relay K1-K4 or K6-K9 is energized, the loop current and voltage are output through a high-precision voltage source and a high-precision ammeter, the on-resistance is measured in combination with the four-wire loop, and the direction error is eliminated by switching the polarity.

[0012] Preferably, it also includes: Step S8: calibrating the on-resistance between the PE terminal of the DC charging gun socket and the resistance test clamp; Connect the DC charging gun to the DC charging gun holder, and remove the two connecting wires of the resistance test clip; connect the two ends of the resistance test clip to the high-precision ammeter and the high-precision voltage source through the first banana head interface and the second banana head interface, respectively, to form a four-wire calibration loop; calculate the on-resistance value between the PE end of the DC charging gun holder and the resistance test clip based on the measurement data of the high-precision ammeter and the high-precision voltage source; Step S9: calibrating the on-resistance between the PE terminal of the AC charging gun socket and the resistance test clip; Connect the AC charging gun to the AC charging gun socket, and remove the two connecting wires of the resistance test clip; connect the two ends of the resistance test clip to the high-precision ammeter and the high-precision voltage source respectively through the first banana head interface and the second banana head interface to form a four-wire calibration loop; switch the calibration loop to the PE terminal of the national standard AC charging gun socket and the resistance test clip through the low-voltage switching unit; perform four-wire calibration, and calculate the on-resistance value between the PE terminal of the AC charging gun socket and the resistance test clip based on the measurement data of the high-precision ammeter and the high-precision voltage source.

[0013] The present invention provides a new energy vehicle charging safety inspection measurement and calibration device and a control method thereof, which have the following beneficial effects: a DC charging gun holder, a BMS simulator, a high-precision ammeter and a high-precision voltmeter are used to form a DC charging measurement and calibration module, so that when the DC charging measurement of the new energy vehicle charging device needs to be calibrated, the DC charging measurement and calibration module simulates the real charging scene and compares with the high-precision measurement to verify the measurement accuracy of the voltage, current and other parameters of the device under test. An insulation resistance calibration module is formed by a high-precision resistor, a high-voltage switching unit and an AC charging gun holder, so that when insulation resistance calibration is required, the insulation resistance calibration module simulates different insulation resistance values ​​to verify the accuracy of the insulation resistance measurement of the device under test in a high-voltage DC / AC environment. A potential equalization calibration module is formed by a high-precision ammeter, a high-precision voltage source and a low-voltage switching unit, which is used to verify whether the on-resistance between the PE terminal and other conductive components in the charging gun holder meets the safety standards. One-button high-precision calibration is achieved by integrating the DC charging measurement and calibration module, the insulation resistance calibration module and the potential equalization calibration module in combination with the BMS simulator and the intelligent resistance switching technology. The four-wire measurement and polarity adaptive circuit are used to solve the problems of contact resistance and direction error, significantly improve the calibration efficiency and accuracy, and are suitable for the metrological certification of new energy vehicle charging equipment. It solves the pain points of low efficiency, poor accuracy, and scattered equipment in traditional calibration methods, and realizes the high efficiency, high precision, and intelligent calibration of new energy vehicle charging equipment. It provides reliable technical support for the annual inspection of charging piles, vehicle-mounted equipment testing, and industry standard certification, and has significant economic benefits and social value. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the present invention or the technical solutions in the prior art, the drawings required for describing the prior art are briefly introduced below.

[0015] Figure 1 A schematic diagram of the structure of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0017] Embodiment 1, as Figure 1 As shown, a new energy vehicle charging safety inspection and calibration equipment includes a DC charging measurement and calibration module, an insulation resistance calibration module and a potential equalization calibration module; The DC charging metering and calibration module includes a DC charging gun holder 1, a BMS simulator 2, a high-precision ammeter 3 and a high-precision voltmeter 4. The first port of the DC charging gun holder 1 is connected to the DC charging gun of the device under test, and the second port of the DC charging gun holder 1 is connected to the load interface 5. The load interface 5 is connected to the external load box through a relay; the high-precision ammeter 3 is connected in series in the DC+ path of the DC charging gun holder 1, and the high-precision voltmeter 4 is connected in parallel between the DC+ and DC- of the DC charging gun holder 1; the BMS simulator 2 communicates with the device under test through the CAN bus; The insulation resistance calibration module includes a main control unit, a high-precision resistor 6, a high-voltage switching unit and an AC charging gun holder 7. The main control unit controls the BMS simulator 2, the high-precision resistor 6 and the high-voltage switching unit through the CAN bus. The high-voltage switching unit is used to control the high-precision resistor 6 to switch to the DC± terminal and PE terminal of the DC charging gun holder 1 or the L / N terminal and PE terminal of the AC charging gun holder 7; The potential equalization calibration module includes a high-precision ammeter 8, a high-precision voltage source 9 and a low-voltage switching unit. The high-precision ammeter 8 is used to measure the calibration loop current. The high-precision voltage source 9 is used to measure the standard excitation voltage. The low-voltage switching unit includes a low-voltage relay group, a first banana head interface 10 and a second banana head interface 11. The first banana head interface 10 and the second banana head interface 11 are respectively connected to the positive and negative poles of the resistance test clip of the device under test. The low-voltage relay group is used to connect the resistance test clip of the device under test to the high-precision ammeter 8 and the high-precision voltage source 9, and the PE end of the AC charging gun socket 7 is connected to the calibration circuit through the low-voltage relay group.

[0018] Among them, the high-voltage switching unit includes relay K5, relay K10, relay K11, relay K12, relay K13, relay K14 and relay K15, the two ends of relay K5 are respectively connected to the PE end of the DC charging gun holder 1 and the high-precision resistor 6, the two ends of relay K10 are respectively connected to the PE end of the AC charging gun holder 7 and the high-precision resistor 6, the two ends of relay K11 are respectively connected to the L / N end of the AC charging gun holder 7 and the high-precision resistor 6, and relay K12, relay K13, relay K14 and relay K15 respectively control the high-precision resistor 6 to be connected to the DC± end of the DC charging gun holder 1; When relay K5, relay K12, relay K13, relay K14 and relay K15 are attracted, the high-precision resistor 6 is connected to the DC± terminal and the PE terminal of the DC charging gun holder 1; When the relay K10 and the relay K11 are attracted, the high-precision resistor 6 is connected to the L / N terminal and the PE terminal of the AC charging gun holder 7 .

[0019] Among them, the DC+ end of the DC charging gun holder 1 is connected to the DC+ end of the external load box through relay K12 and relay K16 respectively, and the DC- end of the DC charging gun holder 1 is connected to the DC- end of the external load box through relay K13 and relay K17 respectively.

[0020] Among them, the low voltage relay group includes relay K1, relay K2, relay K3, relay K4 and relay K6, relay K7, relay K8, relay K9; When the relay K1 and the relay K3 are energized, the positive electrode of the high-precision voltage source 9 is connected to the positive electrode of the resistance test clip through the first banana plug interface 10, forming a positive calibration loop at the PE end of the DC charging gun holder 1; When reverse current is detected, relays K2 and K4 are energized to switch the circuit polarity; Relay K6, relay K7, relay K8 and relay K9 are used to adapt to the L / N polarity switching of the AC charging gun holder 7; When relay K6 and relay K8 are energized, the L and PE terminals of the AC charging gun holder 7 are connected to the calibration circuit; When relay K7 and relay K9 are energized, the N terminal and PE terminal of the AC charging gun socket 7 are connected to the calibration circuit.

[0021] Working principle: The DC charging gun holder 1, BMS simulator 2, high-precision ammeter 3 and high-precision voltmeter 4 form a DC charging measurement calibration module. When the DC charging measurement of the new energy vehicle charging equipment needs to be calibrated, the DC charging measurement calibration module simulates the real charging scene and compares it with the high-precision measurement to verify the measurement accuracy of the voltage, current and other parameters of the tested equipment. The specific principles are as follows: First, establish communication with the device under test through the BMS simulator 2 to simulate the vehicle battery management system (BMS), send battery parameters and receive status feedback to the device under test through the CAN bus; then apply standard current (0-300A) and voltage (0-1500V) to the device under test through the high-precision ammeter 3 and high-precision voltmeter 4 and external load box as calibration reference. By comparing the displayed value of the device under test with the measured value of the standard source, the absolute error and relative error are calculated, so as to effectively determine whether the device meets the measurement standard.

[0022] During the specific work, first insert the DC charging gun of the device under test into the interface of the DC charging gun holder 1, ensure good contact, and then start the calibration procedure. First, control relays K12 and K13 to pull in through the main control unit, activate the CAN bus communication of the BMS simulator 2, and send virtual battery parameters to the device under test. The device under test parses the CAN message and enters the charging preparation state. Then control relays K16 and K17 to pull in, load standard current (such as 200A) and voltage (such as 800V) to the device under test, connect to the 60kW external load box, simulate high-power charging conditions, and verify the dynamic response of the device; at this time, the DC+ loop current of the DC charging gun holder 1 can be monitored in real time through the high-precision ammeter 3; the high-precision voltmeter 4 synchronously measures the DC+ and DC- voltages of the DC charging gun holder 1. After that, by collecting the display value of the device under test and the standard measurement values ​​of the high-precision ammeter 3 and the high-precision voltmeter 4, the accurate error data can be calculated. If the error exceeds the threshold (such as the relative error>1%), a calibration failure report is generated and a prompt is given to adjust the device under test. After that, disconnect all relays to end the calibration process. Save the calibration data and eject the charging gun of the device under test. Through the above process, the DC charging measurement and calibration module can achieve efficient and accurate one-stop measurement certification.

[0023] The insulation resistance calibration module is composed of a high-precision resistor 6, a high-voltage switching unit and an AC charging gun holder 7. When insulation resistance calibration is required, the insulation resistance calibration module simulates different insulation resistance values ​​to verify the accuracy of insulation resistance measurement of the device under test in a high-voltage DC / AC environment. First, a high-precision resistor 6 is used to provide a switchable standard resistance value. In this embodiment, the high-precision resistor 6 includes 50kΩ, 100kΩ, 200kΩ, 200kΩ, 500kΩ, 1MΩ, 2MΩ, 2MΩ, 5MΩ, 10MΩ, 20MΩ, 20MΩ, 50MΩ, 100MΩ, 200MΩ, 200MΩ, 500MΩ, 1GΩ, 2GΩ, 2GΩ, and 5GΩ standard resistance values ​​according to the 1-2-2-5 principle.

[0024] Among them, the "1-2-2-5 principle" is a standardized method for configuring resistor values ​​in grades (this is an existing technology) to ensure that the proportional relationship and logarithmic distribution between the grades are reasonable when the resistor network covers a wide range of resistance values. The core is to generate a series of resistance values ​​by combining the four basic coefficients of 1, 2, 2, and 5, so that the step ratio between adjacent grades remains consistent, thereby optimizing measurement accuracy and calibration efficiency.

[0025] The specific logic of 1-2-2-5 classification is: first take 1, 2, 2, 5 as the basic coefficients, expand them in decimal, and form the following typical classification (unit: Ω): First cycle: 1, 2, 2, 5; Second cycle: 10, 20, 20, 50; Third cycle: 100, 200, 200, 500; Fourth cycle: 1k, 2k, 2k, 5k; ...(and so on, up to the maximum resistance value).

[0026] The present invention configures the above-mentioned standard resistance value through the 1-2-2-5 principle, and each standard resistance value corresponds to an independent relay. By controlling the pull-in of each relay, the high-precision resistor 6 is quickly switched to the target resistance value, so that the resistance simulation range reaches 50kΩ-10GΩ, stepping 10kΩ. And the accuracy can reach 0.1%; it switches different resistance gears through the relay inside the high-precision resistor 6 to simulate the actual insulation fault scenario. Then, the high-voltage switching unit is used to select and switch the DC or AC high-voltage path. And by adopting independent current excitation and voltage detection circuits, contact resistance and lead errors are eliminated.

[0027] When calibrating the insulation resistance, first connect the DC charging gun and AC charging gun of the device under test to the corresponding gun holders, and initialize the high-voltage switching unit and the high-precision resistor 6.

[0028] Then select the corresponding calibration mode: in DC mode, relay K5, relay K12, relay K13, relay K14 and relay K15 are energized to connect the high-precision resistor 6 to the DC± and PE terminals of the DC charging gun socket 1; and in AC mode, relay K10 and relay K11 are energized to connect the high-precision resistor 6 to the L and PE terminals of the AC charging gun socket 7.

[0029] After that, the main control unit controls the opening and closing of the internal relay of the high-precision resistor 6 through the CAN bus, and then controls the high-precision resistor 6 to select the appropriate resistance gear according to the test requirements; then controls the device under test to start the insulation resistance measurement, and obtains the insulation resistance value of the device under test; then compares the actual measurement value with the standard resistance value provided by the high-precision resistor 6, so as to obtain the insulation resistance measurement error of the device under test. If the error is within an acceptable range (for example, the relative error <5%), the main control unit outputs a calibration success report; if the error exceeds the standard, a calibration failure report is generated and the user is prompted to adjust or repair the equipment. After that, the high-precision resistor 6 is controlled to switch to the next resistance gear, and the above steps are re-executed to achieve a multi-gear cycle test effect. When the calibration is completed, the relay is disconnected, the device is restored to the standby state, and the entire insulation resistance calibration process is completed. Through the above process, the insulation resistance calibration module can systematically solve the problems of large contact error, limited range and low safety in traditional calibration, and provide technical guarantees for the safety and compliance of new energy vehicle charging equipment.

[0030] The potential equalization calibration module is composed of a high-precision ammeter 8, a high-precision voltage source 9 and a low-voltage switching unit, which is used to verify whether the on-resistance between the protective ground (PE) terminal in the charging gun holder and other conductive parts (such as the charging gun housing and metal structural parts) meets the safety standards. It adopts a four-wire measurement method through an independent current excitation circuit and a voltage detection circuit to eliminate the influence of contact resistance and wire resistance on the measurement results. The standard excitation voltage is provided by a high-precision voltage source 9 (10mV-10V, accuracy 0.1%), and the high-precision ammeter 8 (0-10A, accuracy 0.2%) measures the loop current to calculate the on-resistance value. The low-voltage switching unit switches the polarity of the four-wire loop through a low-voltage relay group to adapt to the DC charging gun holder 1 and the AC charging gun holder 7. The first banana head interface 10 and the second banana head interface 11 are directly connected to the resistance test clip of the device under test to form a four-wire calibration path.

[0031] When the potential equalization calibration module is working, firstly, the resistance test clamp of the device under test is connected to the calibration device of the present invention through the first banana plug interface 10 and the second banana plug interface 11.

[0032] The main control unit initializes the high-precision voltage source 9 and the high-precision ammeter 8. Then select the calibration mode (DC or AC): In the DC mode, the relay K1 and the relay K3 (or the relay K2 and the relay K4) are energized to form a current path: the PE end of the DC charging gun socket 1 → relay K1 → the first banana head interface 10 → the resistance test clip of the device under test → the second banana head interface 11 → relay K3 → high-precision ammeter 8; a four-wire calibration loop is formed. The output end of the high-precision voltage source 9 is directly connected to the first banana head interface 10 and the second banana head interface 11 to provide a standard excitation voltage (10mV-10V). In AC mode, relay K7 and relay K9 are energized to connect the PE end of the AC charging gun holder 7 to the positive path of the circuit (adapting to the positive pole of L1 / L2 / L3), or relay K6 and relay K8 are energized to connect the PE end of the AC charging gun holder 7 to the positive path of the circuit (adapting to the N pole); then the high-precision voltage source 9 outputs a standard voltage (such as 1V), and the high-precision ammeter 8 measures the current (such as 1A) to simulate the target resistance value (such as 1Ω). When the high-precision ammeter 8 detects that the current direction is reversed (such as -1A), the low-voltage switching unit can be controlled by the central control unit to automatically switch the relay combination; for example, in DC mode, relay K1 and relay K3 are disconnected, and relay K2 and relay K4 are energized; in AC mode, relay K7 and relay K9 are disconnected, and relay K6 and relay K8 are energized. This avoids the influence of the voltage source direction on the resistance measurement of the device under test, and effectively ensures that the test accuracy is not affected by the change of current polarity. After that, the error is calculated by comparing the displayed value of the device under test with the measured on-resistance value, so that the accuracy and safety of the protective grounding terminal of the charging gun socket can be evaluated. If the error exceeds the threshold (such as relative error>5%), a calibration failure report is generated and a prompt is given to adjust the device under test. If the error is within an acceptable range, the calibration is successful and the final calibration result is output. Through the above process, the potential equalization calibration module realizes the precise calibration of the resistance of the DC charging gun socket 1 and the AC charging gun socket 7 through four-wire high-precision measurement and polarity adaptive control. Ensure the safety and reliability of the grounding system of the DC charging gun socket 1 and the AC charging gun socket 7, and provide core protection for the charging safety of new energy vehicles.

[0033] In addition, the calibration device of the present invention can also calibrate the on-resistance between the PE end of the DC charging gun holder 1 and the resistance test clip; connect the DC charging gun to the DC charging gun holder 1, remove the two connecting wires of the resistance test clip, and connect the two ends of the resistance test clip to the high-precision ammeter 8 and the high-precision voltage source 9 through the first banana head interface 10 and the second banana head interface 11 to simulate the four-wire calibration method. The contact resistance between the DC charging gun and the DC charging gun holder 1 is negligible, which fundamentally solves the problem of large contact resistance of the resistance test clip during calibration, and also solves the problem of internal resistance change when switching between different standard resistors. When calibrating the on-resistance between the PE end of the AC charging gun holder 7 and the resistance test clip, the circuit will be switched to the AC charging gun holder 7 through the low-voltage switching unit.

[0034] The present invention realizes one-click high-precision calibration by integrating a DC charging measurement calibration module, an insulation resistance calibration module and a potential equalization calibration module in combination with a BMS simulator 2 and intelligent resistance switching technology. The four-wire measurement and polarity adaptive circuit are adopted to solve the problems of contact resistance and direction error, significantly improve the calibration efficiency and accuracy, and are suitable for the measurement and certification of new energy vehicle charging equipment. It solves the pain points of low efficiency, poor accuracy, and scattered equipment in traditional calibration methods, realizes the high efficiency, high precision and intelligence of the calibration of new energy vehicle charging equipment, and provides reliable technical support for the annual inspection of charging piles, vehicle-mounted equipment testing and industry standard certification, with significant economic benefits and social value.

[0035] Embodiment 2, the present invention also discloses a control method for a new energy vehicle charging safety inspection and calibration device, which comprises the following steps:

[0036] Step S1: Connect the DC charging gun and AC charging gun of the device under inspection to the DC charging gun socket 1 and the AC charging gun socket 7 respectively; Step S2: Connect the positive electrode and the negative electrode of the resistance test clip of the device to be tested to the first banana plug interface 10 and the second banana plug interface 11 respectively; Step S3: DC charging current calibration: energize relay K12 and relay K13, establish a CAN communication link between the BMS simulator 2 and the device under test, and transmit battery parameters; after entering the charging stage, energize relay K16 and relay K17, load standard current or voltage to the device under test, and measure the charging current and voltage with high-precision ammeter 3 and high-precision voltmeter 4 respectively, and compare them with the displayed values ​​of the device under test; Step S4: Current and voltage error calculation: Absolute error: , ; Relative error: ; ; in, is the absolute error of current, is the absolute voltage error; is the current relative error, is the relative voltage error of the equipment under test; is the current value displayed by the device under test, It is the current value displayed by the high-precision ammeter 3; is the voltage value displayed by the device under test, It is the voltage value displayed by the high-precision voltmeter 4; Step S5: Insulation resistance calibration: select DC calibration mode or AC calibration mode; When the DC calibration mode is selected, the relay K5 and the relays K12, K13, K14 and K15 are energized, and the high-precision resistor 6 is controlled through the CAN bus to cut in the resistance value according to the test requirements, and then the device under test is started, and the insulation resistance value of the device under test is obtained; When the AC calibration mode is performed, the relay K11 and the relay K10 are energized, and the high-precision resistor 6 is controlled through the CAN bus to cut in the resistance value according to the test requirements, and then the device under test is started, and the insulation resistance value of the device under test is obtained; Step S6: Calculation of resistance value error: Compare the measurement result with the insulation resistance value of the device under test and calculate the error of the device under test: ; ; in, is the absolute error of the resistor, is the relative error of resistance, The insulation resistance value displayed by the device under test. The insulation resistance value shown for the high-precision resistor 6.

[0037] Step S7: In the potential equalization calibration mode, remove the two wires of the resistance test clip of the device under test, and connect the resistance test clip of the device under test to the calibration device through the first banana head interface 10 and the second banana head interface 11. The banana head interface is connected to the high-precision ammeter 8 and the high-precision voltage source 9 inside the calibration device to form an independent current excitation and voltage measurement loop.

[0038] When the PE end of the DC charging gun socket 1 and the resistance test clip are calibrated for potential equalization, relay K1 and relay K3 are energized to form a current path: PE end of the DC charging gun socket 1 → relay K1 → first banana head interface 10 → resistance test clip of the device under test → second banana head interface 11 → relay K3 → high-precision ammeter 8; a four-wire calibration loop is formed. For example, when simulating a 1Ω standard resistance, when the current indication of the high-precision ammeter 8 is 1A, the high-precision voltage source 9 outputs a voltage of 1V. When the current measured by the high-precision ammeter 8 is negative, the central control unit controls the disconnection of relays K1 and K3, and the energization of relays K2 and K4.

[0039] When calibrating the potential equalization between the PE terminal of the AC charging gun holder 7 and the resistance test clip, the relay K7 and relay K9 are energized to connect the PE terminal of the AC charging gun holder 7 to the positive path of the circuit (adapting to the positive pole of L1 / L2 / L3), or the relay K6 and relay K8 are energized to connect the PE terminal of the AC charging gun holder 7 to the negative path of the circuit (adapting to the N pole); the standard voltage (such as 1V) is output by the high-precision voltage source 9, and the current (such as 1A) is measured by the ammeter to simulate the target resistance value (such as 1Ω). When the current measured by the high-precision ammeter 8 is negative (such as the polarity of the device under test is reversed), the low-voltage switching unit is controlled by the central control unit to automatically energize the reverse relay combination (such as relay K6 and relay K8) to switch the circuit polarity and ensure the measurement accuracy.

[0040] Additionally, it includes: Step S8: calibrate the on-resistance between the PE terminal of the DC charging gun socket 1 and the resistance test clip; Connect the DC charging gun to the DC charging gun holder 1, and remove the two connecting wires of the resistance test clip; connect the two ends of the resistance test clip to the high-precision ammeter 8 and the high-precision voltage source 9 through the first banana head interface 10 and the second banana head interface 11, respectively, to form a four-wire calibration loop; based on the measurement data of the high-precision ammeter 8 and the high-precision voltage source 9, calculate the on-resistance value between the PE end of the DC charging gun holder 1 and the resistance test clip; Step S9: calibrate the on-resistance between the PE terminal of the AC charging gun socket 7 and the resistance test clip; Connect the AC charging gun to the AC charging gun socket 7, and remove the two connecting wires of the resistance test clip; connect the two ends of the resistance test clip to the high-precision ammeter 8 and the high-precision voltage source 9 through the first banana head interface 10 and the second banana head interface 11, respectively, to form a four-wire calibration loop; switch the calibration loop to the PE end of the national standard AC charging gun socket 7 and the resistance test clip through the low-voltage switching unit; perform four-wire calibration, and calculate the on-resistance value between the PE end of the AC charging gun socket 7 and the resistance test clip based on the measurement data of the high-precision ammeter 8 and the high-precision voltage source 9.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A new energy vehicle charging safety inspection and calibration equipment, characterized by: Including DC charging measurement calibration module, insulation resistance calibration module and potential equalization calibration module; The DC charging metering and calibration module comprises a DC charging gun holder (1), a BMS simulator (2), a high-precision ammeter (3) and a high-precision voltmeter (4); the first port of the DC charging gun holder (1) is connected to the DC charging gun of the device under test, and the second port of the DC charging gun holder (1) is connected to the external load box via a load interface (5); the high-precision ammeter (3) is connected in series in the DC+ path of the DC charging gun holder (1), and the high-precision voltmeter (4) is connected in parallel between the DC+ and DC- of the DC charging gun holder (1); the BMS simulator (2) communicates with the device under test via a CAN bus; The insulation resistance calibration module comprises a main control unit, a high-precision resistor (6), a high-voltage switching unit and an AC charging gun holder (7); the main control unit controls the BMS simulator (2), the high-precision resistor (6) and the high-voltage switching unit via a CAN bus; the high-voltage switching unit is used to control the high-precision resistor (6) to switch to the DC± terminal and PE terminal of the DC charging gun holder (1) or the L / N terminal and PE terminal of the AC charging gun holder (7); The potential equalization calibration module comprises a high-precision ammeter (8), a high-precision voltage source (9) and a low-voltage switching unit, wherein the high-precision ammeter (8) is used to measure the calibration loop current, the high-precision voltage source (9) is used to measure the standard excitation voltage, and the low-voltage switching unit comprises a low-voltage relay group, a first banana head interface (10) and a second banana head interface (11), wherein the first banana head interface (10) and the second banana head interface (11) are respectively connected to the positive pole and the negative pole of the resistance test clamp of the device under test, and the low-voltage relay group is used to connect the resistance test clamp of the device under test to the high-precision ammeter (8) and the high-precision voltage source (9), and the PE end of the AC charging gun holder (7) is connected to the calibration circuit through the low-voltage relay group.

2. A new energy vehicle charging safety inspection and calibration equipment according to claim 1, characterized in that: The high-voltage switching unit comprises a relay K5, a relay K10, a relay K11, a relay K12, a relay K13, a relay K14 and a relay K15, wherein two ends of the relay K5 are respectively connected to the PE end of the DC charging gun holder (1) and the high-precision resistor (6), two ends of the relay K10 are respectively connected to the PE end of the AC charging gun holder (7) and the high-precision resistor (6), two ends of the relay K11 are respectively connected to the L / N end of the AC charging gun holder (7) and the high-precision resistor (6), and the relay K12, the relay K13, the relay K14 and the relay K15 respectively control the high-precision resistor (6) to be connected to the DC± end of the DC charging gun holder (1); When relay K5, relay K12, relay K13, relay K14 and relay K15 are attracted, the high-precision resistor (6) is connected to the DC± terminal and the PE terminal of the DC charging gun holder (1); When the relay K10 and the relay K11 are attracted, the high-precision resistor (6) is connected to the L / N terminal and the PE terminal of the AC charging gun holder (7).

3. A new energy vehicle charging safety inspection and calibration equipment according to claim 1, characterized in that: The DC+ end of the DC charging gun holder (1) is connected to the DC+ end of the load interface (5) via relays K12 and K16, respectively, and the DC- end of the DC charging gun holder (1) is connected to the DC- end of the load interface (5) via relays K13 and K17, respectively.

4. A new energy vehicle charging safety inspection and calibration equipment according to claim 1, characterized in that: The low voltage relay group includes relay K1, relay K2, relay K3, relay K4 and relay K6, relay K7, relay K8 and relay K9; When relay K1 and relay K3 are energized, the positive electrode of the high-precision voltage source (9) is connected to the positive electrode of the resistance test clip through the first banana plug interface (10), thereby forming a positive calibration loop at the PE end of the DC charging gun holder (1); When reverse current is detected, relays K2 and K4 are energized to switch the circuit polarity; The relay K6, relay K7, relay K8 and relay K9 are used to adapt to the L / N polarity switching of the AC charging gun holder (7); When relay K6 and relay K8 are energized, the L terminal and the PE terminal of the AC charging gun holder (7) are connected to the calibration circuit; When relay K7 and relay K9 are energized, the N terminal and the PE terminal of the AC charging gun holder (7) are connected to the calibration circuit.

5. The new energy vehicle charging safety inspection and calibration equipment according to claim 1 is characterized in that: The high-precision resistor (6) is a multi-level standard resistor configured according to the 1-2-2-5 principle, and each level of resistance is switched by an independent relay.

6. The control method of the new energy vehicle charging safety inspection and calibration equipment according to any one of claims 1 to 5 is characterized in that: The following steps are involved: Step S1: Connecting a DC charging gun and an AC charging gun of the device to be tested to a DC charging gun holder (1) and an AC charging gun holder (7) respectively; Step S2: connecting the positive electrode and the negative electrode of the resistance test clip of the device under test to the first banana plug interface (10) and the second banana plug interface (11) respectively; Step S3: DC charging current calibration: Relay K12 and relay K13 are energized to establish a CAN communication link between the BMS simulator (2) and the device under test, and the battery parameters are transmitted; after entering the charging phase, relay K16 and relay K17 are energized to load a standard current or voltage to the device under test, and a high-precision ammeter (3) and a high-precision voltmeter (4) respectively measure the charging current and voltage, and compare them with the displayed values ​​of the device under test; Step S4: Current and voltage error calculation: Absolute error: , ; Relative error: ; ; in, is the absolute error of current, is the absolute voltage error; is the current relative error, is the relative voltage error of the equipment under test; is the current value displayed by the device under test, is the current value displayed by the high-precision ammeter (3); is the voltage value displayed by the device under test, is the voltage value displayed by the high-precision voltmeter (4); Step S5: Insulation resistance calibration: select DC calibration mode or AC calibration mode; When the DC calibration mode is selected, relay K5 and relays K12, K13, K14, and K15 are energized, and the high-precision resistor (6) is controlled via the CAN bus to cut in the resistance value according to the test requirements, and then the device under test is started, and the insulation resistance value of the device under test is obtained; When the AC calibration mode is performed, the relay K11 and the relay K10 are energized, and the high-precision resistor (6) is controlled via the CAN bus to switch in the resistance value according to the test requirements, and then the device under test is started, and the insulation resistance value of the device under test is obtained; Step S6: Calculation of resistance value error: Compare the measurement result with the insulation resistance value of the device under test and calculate the error of the device under test: ； ； in, is the absolute error of the resistor, is the relative error of resistance, The insulation resistance value displayed by the device under test. The insulation resistance value displayed for the high-precision resistor (6); Step S7: In the potential equalization calibration mode, the relay K1-K4 or K6-K9 is energized, the loop current and voltage are output through the high-precision voltage source (9) and the high-precision ammeter (8), the on-resistance is measured in combination with the four-wire loop, and the direction error is eliminated by switching the polarity.

7. The control method of the new energy vehicle charging safety inspection and calibration equipment according to claim 6 is characterized in that: Also includes: Step S8: calibrating the on-resistance between the PE terminal of the DC charging gun holder (1) and the resistance test clip; Connect a DC charging gun to a DC charging gun holder (1), and remove the two connecting wires of the resistance test clip; connect the two ends of the resistance test clip to a high-precision ammeter (8) and a high-precision voltage source (9) respectively through a first banana head interface (10) and a second banana head interface (11), so as to form a four-wire calibration loop; calculate the on-resistance value between the PE terminal of the DC charging gun holder (1) and the resistance test clip based on the measurement data of the high-precision ammeter (8) and the high-precision voltage source (9); Step S9: calibrating the on-resistance between the PE terminal of the AC charging gun holder (7) and the resistance test clamp; Connect the AC charging gun to the AC charging gun holder (7), and remove the two connecting wires of the resistance test clip; connect the two ends of the resistance test clip to the high-precision ammeter (8) and the high-precision voltage source (9) respectively through the first banana head interface (10) and the second banana head interface (11), so as to form a four-wire calibration loop; and switch the calibration loop to the PE end of the national standard AC charging gun holder (7) and the resistance test clip through the low-voltage switching unit; Perform four-wire calibration and calculate the on-resistance value between the PE terminal of the AC charging gun socket (7) and the resistance test clamp based on the measurement data of the high-precision ammeter (8) and the high-precision voltage source (9).

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