An electricity safety management system for battery vehicle charging piles

Abstract

The present invention discloses an electricity safety management system for battery vehicle charging piles. It includes a main control module, a main power module, an acquisition module, an energy metering module, a charging switch control module, a communication module and a cloud server. The acquisition module collects data such as electrical characteristics and charging circuit temperature generated when the battery vehicle is charging, including voltage, current, power and leakage current. After simple filtering and sampling in the main control module, the data is packaged into electrical characteristic data and sent to the cloud server. The cloud server analyzes and compares the received electrical characteristic data based on the kernel density feature model to achieve safety monitoring, and automatically controls the charging pile to cut off power and alarm when a safety hazard occurs to ensure electricity safety. The model library of the cloud server stores a large number of models and has self-learning capabilities. It can effectively identify most battery vehicles on the market, so as to provide a reference for whether the battery of the battery vehicle is normal in the event of a sudden safety accident.

Description

Technical Field

[0001] The present invention belongs to the field of electronic information technology, relates to circuit safety monitoring, and particularly relates to an electricity safety management system for battery vehicle charging piles. Background Art

[0002] In recent years, electric scooters have become a primary mode of transportation for the public. Due to limited space within the vehicle, the battery capacity of electric scooters is typically limited, requiring frequent charging. As the number of electric scooter users continues to grow, concerns about charging safety are also growing. Currently, most public charging stations focus on preventing theft during charging, while only some incorporate safety concerns raised by prolonged charging. To mitigate overheating caused by prolonged charging, charging stations are equipped with remote on / off functions, automatic power-off upon full charge, and overload protection measures, which can mitigate the risk of battery fires and explosions to a certain extent. However, accurate detection of abnormal wire temperatures, arc faults, or circuit leakage that may occur during charging remains limited. Furthermore, the inability to identify the type of electric scooter connected to the charging station's main circuit makes it difficult to pinpoint the specific cause of a fire. Summary of the Invention

[0003] In order to address the shortcomings of the existing technology, the present invention proposes an electricity safety management system for electric vehicle charging piles, which collects data such as the electrical characteristics and charging line temperature generated when the electric vehicle battery is charging, performs safety monitoring in the cloud server, and automatically controls the charging pile to cut off power and alarm when there are safety hazards in the line to ensure electricity safety.

[0004] A power safety management system for battery vehicle charging piles includes a main control module, a main power module, a collection module, an electric energy metering module, a charging switch control module, a communication module and a cloud server.

[0005] The main power supply module is connected to the main circuit of the charging pile, steps down the voltage of the 220V mains electricity, and provides operating voltage and reference voltage for other modules in the system.

[0006] The acquisition module is used to collect the voltage, current, leakage current and line temperature of the charging pile and send them to the main control module.

[0007] Preferably, the acquisition module acquires the current flowing in the main circuit of the charging pile through a Hall current sensor, acquires the main circuit voltage through an AC voltage transformer, and acquires the leakage current of the main circuit through a zero-sequence current sensor.

[0008] The electric energy metering module collects the voltage and current of each charging control branch and calculates the power through the electric energy metering IC chip.

[0009] The main control module samples and analyzes the charging pile main circuit line information transmitted by the acquisition module, uploads it to the cloud server through the communication module, and controls the charging switch control module and returns the operation results according to the instructions returned by the cloud server. The specific sampling and analysis process is as follows:

[0010] According to the Nyquist sampling theorem, the main control module uses a sampling frequency that is twice the maximum frequency of the original signal, discretely samples the signal output by the acquisition module, performs windowing and truncation, and then performs DFT analysis on the spectrum to ultimately obtain a waveform cluster representing the battery charging of the electric vehicle. The DFT defines the N-point discrete Fourier transform of a finite length sequence x(n) of length M as:

[0011]

[0012] Where k = 0, 1...N-1. To approximate the spectrum of a continuous signal T, the spectrum of the continuous signal is periodically extended with the sampling frequency Fs as the period. The spectrum is sampled according to the spectral resolution Fs / N to obtain the next period Fs. When the sinusoidal signal frequency f is one of the frequencies represented by the sampling frequency Fs, the error is reduced by calculating the repetition value of the current spectrum line. Ideally, the maximum amplitude K of the signal x(t) corresponds to the input sinusoidal signal frequency f:

[0013]

[0014] Based on different input signals, the corresponding frequency and amplitude information can be calculated. This information contains information about different characteristic load components. The processed electrical characteristic information is used to reflect the unique charging status information of an electric vehicle battery and uploaded to the cloud server as a basis for identification.

[0015] The cloud server's model library stores kernel density characteristic models and current waveform models for different types of electric vehicle batteries during normal charging. The cloud server first calculates the Euclidean distance between the electrical characteristic information sent by the main control module and the kernel density characteristic model stored in the model library to determine the battery type of the electric vehicle being charged. It then determines whether the electric vehicle is currently charging normally based on the electric vehicle type and a set power threshold. If the charging power exceeds the set power threshold, a command is sent to the main control module, causing the charging station to be powered off via the charging switch control module. If the charging power is within the set power threshold, a command is sent to the main control module to determine whether a fault arc exists based on the current data. If so, a command is sent to the main control module to cause the charging station to be powered off via the charging switch control module.

[0016] To prevent misjudgment of electric vehicle batteries that are not in the model library in the actual production environment, kernel density estimation is used to perform a secondary test on the feature parameters to construct the feature model. The principle of the kernel density estimation method is to use the observed data to estimate the density function when the probability distribution of a certain event is unknown, while considering the influence of the distance between the data. It is generally believed that data with closer distances have a greater impact on each other, while data with farther distances have a smaller impact. Therefore, kernel density estimation is more accurate in global estimation, especially when the sample size is large enough. The process of establishing a kernel density feature model is as follows:

[0017] Collect the electrical characteristic information x of different types of electric vehicle batteries during the charging process, establish a data set, select the KDE (kernel density estimate) method as the density estimation method, and build a feature model for the data in the data set. The modeling formula is:

[0018]

[0019] Where m is the eigenvalue, s is the size of the data set, i represents the length of each set of data in the data set, h k Represents the window width of each eigenvalue, φ is the standard normal density, h=0.9*min(δ,IQR / 1.34)*n -1 / 5 is the window height, where IQR is the interquartile range of the data.

[0020] The fault arc judgment process is as follows:

[0021] The fault arc feature extraction algorithm based on AR model is used to extract the fault arc, and its m-order parameter is:

[0022] a m (i) = a m-1 (i)+a m (m)a m-1 (mi)

[0023] Where i = 1, 2,…, m.

[0024] Calculate the third-order Burg model parameters of the working current of the battery of the electric vehicle during normal charging, and establish a matching template library A in the cloud R =f(a r1 ,a r2 ,a r3 ), and then calculate the third-order Burg model parameters for the received real-time current waveform to obtain its characteristic vector A T =f(a r1 ,a r2 ,a r3 ), calculate the Euclidean distance d(A R ,AT ):

[0025]

[0026] When d(A R ,A T ) is significantly different from the set threshold, indicating that a fault arc has occurred.

[0027] The present invention has the following beneficial effects:

[0028] 1. This system has functions such as battery type detection, charging line abnormality protection, overload protection, remote control, and early warning message push. The cloud server has a faster data processing capability than the embedded microcontroller, and can realize big data processing and characteristic model algorithms that the microcontroller cannot achieve, thereby realizing a highly reliable, highly safe, and highly intelligent battery charging system.

[0029] 2. A magnetic latching relay is used as the control circuit, which has the advantages of stable performance, low power consumption, small size, energy saving and environmental protection, and large load capacity. The magnetic latching relay only requires a pulse to operate, and the transient current at the moment of operation is very low, so it can control high-power circuits with very low power consumption.

[0030] 3. The module circuit has a high degree of integration. Most of the electronic components in all modules can be made of surface mount components, which greatly reduces the size of the device and makes the device more integrated. Compared with traditional large battery vehicle charging devices, it has the characteristics of small size, light weight, and easy installation and disassembly.

[0031] 4. The cloud computing solution based on the Internet of Things cloud platform is adopted. Through a series of safety detection algorithms, it can timely and effectively control the disconnection of the charging line, avoid the occurrence of most electric vehicle charging safety accidents, and promptly inform users through mobile phone applications; through the cloud-based nearly 100 model library recognition and self-learning capabilities, it can effectively identify most electric vehicle batteries on the market, which is convenient for providing a reference for whether the electric vehicle battery is normal in the event of an emergency safety accident. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a framework diagram of the electricity safety management system for battery vehicle charging piles;

[0033] Figure 2 This is a schematic diagram of the main power supply module circuit in the embodiment;

[0034] Figure 3 This is a circuit schematic diagram of the current acquisition module in the embodiment;

[0035] Figure 4 This is a circuit schematic diagram of the voltage acquisition module in the embodiment;

[0036] Figure 5 This is a circuit schematic diagram of the leakage current collection module in the embodiment;

[0037] Figure 6 This is a circuit schematic diagram of the line temperature acquisition module in the embodiment;

[0038] Figure 7 This is a circuit schematic diagram of a charging switch control module in an embodiment;

[0039] Figure 8 The circuit diagram of the magnetic latching relay in the embodiment

[0040] Figure 9 This is a circuit schematic diagram of the electric energy metering module in the embodiment;

[0041] Figure 10 This is a schematic diagram of the main control module circuit in the embodiment;

[0042] Figure 11 Flowchart of the charging system software in the embodiment. DETAILED DESCRIPTION

[0043] The present invention will be further explained below with reference to the accompanying drawings;

[0044] like Figure 1 As shown, a power safety management system for battery vehicle charging piles includes a main control module, a main power module, a collection module, an energy metering module, a charging switch control module, a communication module, and a cloud server. The collection module includes an electrical characteristic collection module, a leakage collection module, and a line temperature collection module.

[0045] like Figure 2 As shown in the figure, the main power module is connected to the main circuit of the charging pile, converting the 220V AC power into 12V, then into 5V, and then into 3.3V and 2.5V, and further realizing the conversion between digital voltage and analog voltage, providing stable operating voltage and reference voltage for other modules in the system.

[0046] In the 220V to 12V power supply circuit, select the HI-LINK AC-DC12V first power supply module M1 for isolation and voltage stabilization. Pin 1 of the first power supply module M1 is connected to the neutral wire, pin 2 is connected to the live wire, pin 4 outputs 12V voltage, and pin 3 is the digital ground.

[0047] In the 12V to 5V power supply circuit, select a voltage regulator model PW2815. Pin 1 of the eleventh voltage regulator U11 is connected to the 12V voltage output by the first power module M1, pin 3 is connected to pin 1 through the thirty-second resistor R32, and pins 6 and 9 are connected to digital ground. Pin 4 is grounded through the thirty-third resistor R33. The positive end of the thirty-third capacitor C33 and one end of the second chip capacitor CF2 are connected to pin 1 of the eleventh voltage regulator U11, and the other end is connected to digital ground. Pin 7 of the eleventh voltage regulator U11 is connected to pin 8 through the twenty-eighth capacitor C28. One end of the third inductor L3 is connected to pin 8 of the eleventh voltage regulator U11, and the other end is connected to the thirty-first resistor R31, the thirty-first capacitor C31, the thirty-second capacitor C32, and one end of the first chip capacitor CF1, and outputs a 5V voltage. The other end of the 31st resistor R31 is connected to pin 4 of the 11th regulator U11. The other ends of the 31st capacitor C31, the 32nd capacitor C32, and the first chip capacitor CF1 are connected to digital ground. The cathode of the fourth diode D4 is connected to pin 8 of the 11th regulator U11, and the anode is connected to digital ground.

[0048] In the 5V-to-3.3V power supply circuit, the first voltage regulator V1 is an AMS1117-3V3. Pin 3 of the first voltage regulator V1 is connected to the 5V output of the eleventh voltage regulator U11, while pin 2 outputs the stepped-down digital 3.3V voltage. Pin 1 is connected to digital ground. One end of the 22nd and 23rd electrolytic capacitors C22 and the positive terminal of the second tantalum capacitor E2 are connected to pin 3 of the first voltage regulator V1, while the other ends are connected to digital ground. The positive terminals of the 23rd electrolytic capacitor C23 and the first tantalum capacitor E1 are connected to pin 2 of the first voltage regulator V1, while the other ends are connected to digital ground. The positive electrode of the first light-emitting diode LED1 is connected to the 2nd pin of the first voltage regulator V1 through the twenty-eighth resistor R28, and the negative electrode is connected to the digital ground. When the 2nd pin of the first voltage regulator V1 can output voltage normally, the first light-emitting diode LED1 lights up, indicating that the 5V to 3.3V power supply circuit is working normally; the 3.3V voltage is led out through the first magnetic bead L1 to obtain the isolated 3.3V voltage, and the digital ground and the analog ground are connected through the second magnetic bead L2.

[0049] In the 2.5V reference voltage output circuit, pin 1 of the REF3025 voltage reference chip U15 is connected to the 5V voltage output by the eleventh voltage regulator U11, pin 2 outputs the 2.5V reference voltage, and pin 3 is connected to analog ground. The positive end of the twenty-sixth and twenty-seventh capacitors C26 and C27, as well as the positive end of the twenty-ninth electrolytic capacitor C29, are connected to pin 1 of the voltage reference chip U15, with the other ends connected to analog ground. One end of the thirty-fourth capacitor C34 is connected to pin 2 of the voltage reference chip U15, with the other end connected to analog ground. The 2.5V reference voltage output by the voltage reference chip U15 can be used as a reference signal for current zero-crossing detection and voltage division during the electrical characteristic acquisition process.

[0050] The electrical characteristics acquisition module is used to collect the current and voltage information of the main circuit. Figure 3 As shown, the system includes sensor acquisition and conditioning. The main circuit live wire passes through the sensing hole of Hall sensor U4. The Hall sensor output is filtered, amplified, and then transmitted to the control module. Hall sensor U4 is model HCS-ES5-75A, and the operational amplifier used for the operational processing is model OPA2333A. Pin 1 of Hall sensor U4 is connected to one end of the third and fourth capacitors C3 and C4 and an analog 5V voltage, while pin 2 is connected to the other end of the third and fourth capacitors C3 and C4 and an analog ground. Pin 4 is connected to one end of the nineteenth and tenth capacitors C9 and C10 and a 2.5V voltage, and the other end of the nineteenth and tenth capacitors C9 and C10 is connected to an analog ground. Pin 3 of Hall sensor U4 outputs the detected main circuit current through capacitor C12, which is then connected to pin 5 of the third operational amplifier U3 via resistor R16 for amplification. Pin 5 of the third op amp U3 is connected to analog ground via the fifteenth resistor R15. Pin 8 is connected to an analog 3.3V voltage and to analog ground via the second capacitor C2, providing operating voltage for the third op amp U3. Pin 6 is connected to one end of the tenth and twelfth resistors R10 and R12, respectively. Pin 7 is connected to the seventh capacitor C7, one end of the seventh resistor R7, and the other end of the tenth resistor R10. One end of the sixth capacitor C6 is connected to the other end of the seventh resistor R7. The other end of the seventh capacitor C7 is connected to the cathode of the third diode D3 and the other end of the seventh resistor R7. The other ends of the sixth, seventh, and eighth capacitors C6, C7, and C8, as well as the anode of the third diode D3, are connected to analog ground. The cathode of the third diode D3 outputs the amplified current detection signal to the main control module. The third diode D3 is used to indicate whether the current acquisition unit has detected a current signal. Pin 3 of the third op amp U3 is connected to pin 7 via the eleventh resistor R11 for zero-crossing detection. Pin 2 of the third op amp U3 is connected to one end of the fifth and sixth resistors R5 and R6. The other end of the fifth resistor R5 is connected to a 2.5V reference voltage, and the other end of the sixth resistor R6 is connected to analog ground. After the 2.5V reference voltage is divided by the fifth and sixth resistors R5 and R6, the voltage input to pin 2 of the third op amp U3 is 1.5V, providing a comparison signal for zero-crossing detection. Pin 1 of the third op amp U3 outputs the zero-crossing detection result to the main control module.

[0051] The Hall effect sensor converts a continuous current signal into a voltage signal. Compared to ordinary CTs, it has a higher frequency measurement range and can accurately reflect the current waveform. The relationship between the output voltage of the Hall effect sensor and the line current is:

[0052]

[0053] The voltage acquisition part collects the main circuit voltage through the voltage transformer. In order to ensure that the output voltage signal meets the sampling range of the DSP chip, the output of the voltage transformer needs to be stepped down. Figure 4 As shown, pin 2 of the voltage transformer T1 is connected to the neutral line of the charging pile main circuit through the twentieth resistor R20, and pin 1 is connected to the live wire of the main circuit. Pin 4 is connected to the analog ground, and pin 3 outputs the collected voltage signal. The two ends of the twenty-second resistor are respectively connected to pins 3 and 4 of the voltage transformer T1. One end of the fifteenth capacitor C15 is connected to pin 3 of the voltage transformer T1, and the other end is connected to one end of the twenty-first, twenty-third, and twenty-fourth resistors R21, R23, and R24. The other end of the twenty-first resistor R21 is connected to the 2.5V reference voltage, and the other end of the twenty-fourth resistor R24 ​​is connected to the analog ground. The other end of the twenty-third resistor R23 is connected to the main control module, which converts the AC voltage into a small AC signal less than 3V through the voltage transformer and transmits it to the main control module. One end of the sixteenth capacitor C16 is connected to the analog ground, and the other end is connected to the other end of the twenty-third resistor R23.

[0054] The main control module samples the analog voltage output of the voltage transformer through a 12-bit A / D converter and calculates the voltage V(i) from the digital quantity using the formula:

[0055]

[0056] Where V ref is the reference voltage of the A / D converter. In this embodiment, V ref =3.3V. At this time, the conversion formula from the voltage V(i) at the sampling point to the actual current of the power supply line is derived as follows:

[0057]

[0058] Where V0 is the output voltage of the transformer when the line current is 0, I max is the maximum measurable current of the transformer, and ΔV is the maximum value of the transformer's linear output voltage change.

[0059] The leakage current acquisition module includes sensor acquisition and operational amplification. The zero-sequence current sensor acquires the leakage current in the main circuit and transmits it to the main control module after amplification. Figure 5As shown, the two ends of the fourteenth resistor R14 are connected to the two pins of the zero-sequence current sensor P1, respectively. Pin 2 of the zero-sequence current sensor is connected to analog ground, and pin 1 is connected to pin 5 of the second op amp U2 via the thirteenth resistor R13, amplifying the collected leakage current information. The second op amp U2 is an OPA2333A, with pins 1, 2, 3, and 4 connected to analog ground. Pin 8 is connected to an analog 3.3V voltage and to analog ground via the first capacitor C1, providing a stable voltage for op amp operation. Pin 6 of the second op amp U2 is connected to analog ground via the ninth resistor R9 and to pin 7 via the first feedback resistor RF1, forming a feedback loop. The anode of the first diode D1 is connected to pin 7 of the second op amp U2, and the cathode is connected to the fifth capacitor C5, one end of the eighth resistor R8, and the cathode of the second diode D2. The fifth capacitor C5, the other end of the eighth resistor R8, and the anode of the second diode D2 are connected to analog ground. Pin 7 of the second op amp U2 outputs the amplified leakage current, which is then connected to the control module after passing through the first diode D1. When a ground fault occurs, the vector sum of the currents in each phase is not zero. The fault current generates magnetic flux in the annular core of the zero-sequence current transformer, and an induced voltage is generated on the secondary side of the zero-sequence current transformer. The fault current is proportional to the induced current. A signal output can be obtained from the secondary winding of the zero-sequence current transformer to measure the residual current.

[0060] like Figure 6 As shown, a NCT3950 thermistor is used to collect line temperature. When the temperature of the charging pile's main line changes, the resistance of the thermistor also changes, causing the output voltage to change. The cloud server determines the temperature of the charging line based on the voltage output from the temperature acquisition. One end of the thermistor NTC1 is connected to one end of the fourteenth capacitor C14 and the analog ground. The other end is connected to the analog 3.3V voltage through the seventeenth resistor R17 and to the other end of the fourteenth capacitor C14, outputting a voltage signal reflecting the main circuit temperature.

[0061] In order to save the IO port resources of the main control chip, the charging switch control module is implemented in the form of a shift register to control the opening and closing of the charging branch. In order to solve the problem of insufficient driving capability, a driver chip is introduced to drive the magnetic latching relay; 3 shift registers and 4 driver chips are used in combination to control the opening and closing of 12 charging piles. Figure 7As shown, pin 136 of the first chip U1 of the main control module is connected to pin 14 of the third shift register, pin 135 is connected to pin 12 of the third shift register IC3, the first shift register IC1, and the second shift register IC2, and pin 134 is connected to pin 11 of the third shift register IC3, the first shift register IC1, and the second shift register IC2; pins 10 and 16 of the third shift register IC3, the first shift register IC1, and the second shift register IC2 are all connected to a 3.3V power supply, and pin 13 is connected to a digital ground; pin 9 of the third shift register IC3 is connected to pin 14 of the first shift register IC1, and pin 9 of the first shift register IC1 is connected to pin 14 of the second shift register IC2, and pin 9 of the second register IC2 is left floating; pins 15, 7, 6, 5, 4, 3, 2, and 1 of the third shift register IC3 are connected to the first shift register IC1 Pins 15, 7, 6, 5, 4, 3, 2, and 1 of the first shift register IC2, as well as pins 15, 7, 6, 5, 4, 3, 2, and 1 of the second shift register IC2 are respectively connected to pin 1 of the sixth driver chip U6, pins 1, 2, 3, 4, 5, 6, and 7 of the fifth driver chip U5, pin 7 of the sixth driver chip U6, pin 5 and 6 of the eighth driver chip U8, pin 2, 3, 4, 5, and 6 of the sixth driver chip U6, pin 7 of the seventh driver chip U7, pin 7 of the eighth driver chip U8, and pin 1, 2, 3, 4, 5, and 6 of the seventh driver chip U7; pin 8 of the fifth driver chip U5, the sixth driver chip U6, the seventh driver chip U7, and the eighth driver chip U8 are connected to the digital ground, and pin 9 is connected to the 12V voltage; the structure of the magnetic latching relay of each branch is the same, and only the magnetic latching relay of the first branch is introduced here, such as Figure 8 As shown, pin 5 of the first relay JK1 is connected to a 12V voltage, pins 1 and 2 are connected to pin 16 of the sixth driver chip U6 and pin 10 of the fifth driver chip U5 respectively, and pins 4 and 3 are connected to a charging socket.

[0062] like Figure 9As shown, the 220V mains voltage is converted to 3.3V voltage through the power module, and after current limiting and voltage division, it is connected to the electric energy metering chip. The main control chip selects data exchange with the electric energy metering chips of different charging branches by controlling the analog switch chip. Specifically, the 220V voltage is converted to 3.3V voltage and mains ground by the second power module M2, and is grounded in sequence through the thirty-sixth resistor R36, the thirty-seventh resistor R37, the thirty-eighth resistor R38, the thirty-ninth resistor R39, the fortieth resistor R40, and the forty-first resistor R41 to limit current and divide voltage. The thirty-fifth capacitor C35 is connected in parallel at both ends of the forty-first resistor R41, and the voltage of the forty-first resistor R41 is connected to the 3rd pin of the tenth chip U10; the 4th pin of the first relay JK1 is connected to one end of the twenty-seventh resistor R27 and the twenty-ninth resistor R29; the other end of the twenty-ninth resistor R29 and the thirty-sixth resistor R36 are connected to the 3.3V voltage and the mains ground. One end of R30 is connected to the mains ground, the other end of the twenty-seventh resistor R27 is connected to one end of the twenty-first capacitor C21 and pin 1 of the tenth chip U10, the other end of the thirtieth resistor R30 is connected to one end of the twenty-fourth capacitor C24 and pin 2 of the tenth chip U10, the other ends of the twenty-first capacitor C21 and the twenty-fourth capacitor C24 and pin 4 of the tenth chip U10 are connected to the mains ground; pin 8 of the tenth chip U10 is connected to a 3.3V voltage and grounded through the twenty-fifth capacitor C25; pin 5 of the tenth chip U10 is grounded through the thirtieth capacitor C30; pins 7 and 6 of the tenth chip U10 output power metering data and are connected to the thirteenth optical fiber. The 4th pin of the optocoupler U13 and the 2nd pin of the fourteenth optocoupler U14 are connected; the 3.3V voltage is connected to the 4th pin of the thirteenth optocoupler U13 and the 1st pin of the fourteenth optocoupler U14 through the thirty-fourth resistor R34 and the forty-third resistor R43 respectively; the 3.3V digital voltage is connected to the 1st pin of the thirteenth optocoupler U13 through the thirty-fifth resistor R35, and the 2nd pin of the thirteenth optocoupler U13 is connected to the 9th pin of the fifth analog switch chip IC5; the 3.3V digital voltage is connected to the 4th pin of the fourteenth optocoupler U14 and the 9th pin of the fourth analog switch chip IC4 through the forty-second resistor R42, and the 3rd pin of the fourteenth optocoupler U14 is connected to the mains ground; the main control module Pins 116, 115, 112, and 111 of the first chip U1 are respectively connected to pins 10, 11, 14, and 13 of the fourth analog switch chip IC4 and the fifth analog switch chip IC5, for switching the communication electric energy metering branch; the 3.3V digital voltage is connected to pin 24 of the fourth analog switch chip IC4 and the fifth analog switch chip IC5, and the 12th and 15th pins of the fourth analog switch chip IC4 and the fifth analog switch chip IC5 are connected to the digital ground. Pin 1 of the fourth analog switch chip IC4 and the fifth analog switch chip IC5 is respectively connected to pins 113 and 114 of the first chip U1 of the main control module.

[0063] like Figure 10As shown, pins 55, 56, and 57 of the first chip U1 in the main control module are connected to the analog ground through the thirteenth and eleventh capacitors and the eighteenth resistor respectively, and pin 43 is directly connected to the analog ground; pins 3, 8, 14, 22, 30, 60, 70, 83, 92, 103, 106, 108, 118, 120, 125, 140, 144, 147, 155, 160, 166, and 171 are directly connected to the digital ground; pin 104 is connected to one end of the first crystal oscillator Y1 and then connected to the digital ground through the eighteenth capacitor C18, and pin 102 is connected to the other end of the first crystal oscillator Y1 and then connected to the digital ground through the nineteenth capacitor C19; pins 81 and 82 are connected through the seventeenth capacitor C17; pins 32, 58, 33, and 44 are directly connected to the analog ground ; Pins 34 and 45 are directly connected to the 3.3V analog voltage; pins 84, 9, 71, 93, 107, 121, 143, 159, and 170 are directly connected to the 3.3V digital voltage; pins 25, 26, and 142 are connected to the 3.3V digital voltage through the twenty-fifth, twenty-sixth, and nineteenth resistors R25, R26, and R19 respectively; pins 169, 172, 173, and 174 are connected to the 3.3V digital voltage through the first, second, third, and fourth resistors R1, R2, R3, and R4 respectively; the 3.3V voltage is connected to pin 8 of the ninth storage chip U9 and connected to the digital ground through the twentieth capacitor C20, and pins 1, 2, 3, 4, and 7 of the ninth storage chip U9 are directly connected to the digital ground, and pins 5 and 6 are connected to pins 75 and 74 of the first chip U1 pair respectively, for storing device related information.

[0064] like Figure 11 As shown, the system first powers on and initializes. Upon receiving a charging request from the cloud server, it extracts the charging branch from the request and activates the corresponding relay. It then determines whether an electric vehicle has connected to the charging branch within one minute. If an electric vehicle has connected to the charging branch within one minute, the system sends the collected electrical characteristics to the cloud server and waits for a shutdown command from a non-electric vehicle. If a shutdown command is received from a non-electric vehicle, the system controls the relay to close and reports the shutdown information to the cloud server. If no shutdown command is received from a non-electric vehicle, the system waits for an abnormal shutdown command and simultaneously activates the charging timer to periodically read energy data. If an abnormal shutdown command is received, the system controls the relay to close and reports the shutdown information to the cloud server. If no abnormal shutdown command is received, the system waits for charging to complete, then controls the relay to close and reports the shutdown information to the cloud server. If no electric vehicle has connected to the charging branch within one minute, the system controls the relay to close and reports the shutdown information to the cloud server.

Claims

1. A power safety management system for battery vehicle charging piles, characterized by: An electricity safety management system for battery vehicle charging piles, including a main control module, a main power module, a collection module, an energy metering module, a charging switch control module, a communication module and a cloud server; The main power supply module is connected to the main circuit of the charging pile, steps down the 220V mains voltage, and provides operating voltage and reference voltage for other modules in the system; the acquisition module is used to collect the voltage, current, leakage current and line temperature of the charging pile, and send them to the main control module; the power metering module collects the voltage and current of each charging control branch and calculates the power through the power metering IC chip; the main control module samples and analyzes the charging pile line information transmitted by the acquisition module. According to the Nyquist sampling theorem, the sampling frequency is twice the maximum frequency of the original signal, and the signal output by the acquisition module is discretely sampled. After windowing and truncation, the spectrum is analyzed by DFT to obtain a waveform cluster representing the battery charging of the electric vehicle. The waveform cluster is uploaded to the cloud server through the communication module, and the charging switch control module is controlled and the operation results are transmitted back according to the instructions returned by the cloud server. The cloud server's model library stores kernel density feature models and current waveform models of different types of battery vehicles during normal charging. The cloud server first calculates the Euclidean distance between the electrical feature information sent by the main control module and the kernel density feature model stored in the model library to determine the battery type of the charged battery vehicle. Then, based on the battery vehicle type and the set power threshold, it determines whether the current battery vehicle is in a normal charging state. If the charging power exceeds the set power threshold range, an instruction is sent to the main control module to control the charging pile to be powered off through the charging switch control module. If the charging power is within the set power threshold range, it is determined whether there is a fault arc based on the current data. If so, an instruction is sent to the main control module to control the charging pile to be powered off through the charging switch control module. The fault arc judgment process is as follows: the fault arc is extracted using the fault arc feature extraction algorithm based on the AR model; Calculate the third-order Burg model parameters of the working current of the battery of the electric vehicle during normal charging, and establish a matching template library in the cloud , and then calculate the third-order Burg model parameters for the received real-time current waveform to obtain its characteristic vector , calculate the Euclidean distance between the two ,when When the difference from the set threshold is large, it indicates that a fault arc has occurred.

2. The power safety management system for battery vehicle charging piles according to claim 1, characterized in that: The acquisition module acquires the current flowing through the main circuit of the charging pile through a Hall current sensor, acquires the main circuit voltage through an AC voltage transformer, and acquires the leakage current of the main circuit through a zero-sequence current sensor.

3. The power safety management system for battery vehicle charging piles according to claim 1, characterized in that: The DFT spectrum analysis is as follows: a finite length sequence x(n) of length M is subjected to a discrete Fourier transform, the spectrum changes when the continuous signal T is approximated, the continuous signal spectrum is periodically extended with the sampling frequency Fs as a period, the spectrum is sampled according to the spectrum resolution Fs / N, and the next period Fs is obtained; when the sinusoidal signal frequency f is one of the frequencies represented by the sampling frequency Fs, the error is reduced by calculating the retest value of the current spectrum line; in the ideal case, the maximum frequency-amplitude value K of the signal x(t) corresponds to the input sinusoidal signal frequency f; the corresponding frequency and amplitude information can be calculated according to different input signals.

4. The power safety management system for battery vehicle charging piles according to claim 1, characterized in that: The process of building a kernel density feature model on the cloud server is as follows: Collect the electrical characteristic information x of different types of electric vehicle batteries during the charging process, establish a data set, select the KDE method as the density estimation method, and build a feature model for the data in the data set.

5. The power safety management system for battery vehicle charging piles according to claim 1, characterized in that: In one charging switch control module, three shift registers and four driver chips are used to control the switching state of 12 magnetic latching relays; one charging switch control module is used to control the on and off of the main circuits of 12 charging piles.

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