Online detection method for micro short circuit of high-voltage circuit board of new energy automobile

Abstract

The invention discloses a new energy automobile high-voltage circuit board micro short circuit online detection method, which comprises the steps of injecting a multi-band detection signal into a to-be-detected loop in a live operation state of a high-voltage circuit board, and collecting a response current signal of the to-be-detected loop in real time through a high-precision current sensor, and extracting the phase offset of the response current signal in a specific characteristic frequency band, judging the occurrence of a micro-short circuit fault based on a dynamic comparison result of the phase offset and a preset threshold value, and isolating the electrical connection between the high-voltage main circuit and the detection system.

Description

Technical Field

[0001] This invention relates to the field of circuit board technology, specifically to an online detection method for micro-short circuits on high-voltage circuit boards for new energy vehicles. Background Technology

[0002] Currently, offline insulation resistance measurement or AC impedance spectroscopy analysis is commonly used for micro-short circuit testing of high-voltage circuit boards in new energy vehicles.

[0003] Traditional methods require disconnecting the high-voltage power supply circuit for detection, making real-time monitoring of the operating status impossible. Existing online detection technologies are mostly based on single-frequency signal injection, which lacks sufficient sensitivity for identifying leakage currents at the micro-milliampere level and fails to address the safety isolation issue between the detection system and the high-voltage main circuit. In particular, for initial micro-short circuit faults in the 100-500 microampere range, existing solutions suffer from false alarm rates exceeding 32% due to electromagnetic interference and load fluctuations. A more significant drawback is that phase characteristic analysis has not been used for online micro-short circuit diagnosis, which is a key indicator for identifying capacitive leakage faults. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one objective of this invention is to provide an online detection method for micro-short circuits on high-voltage circuit boards in new energy vehicles, comprising: In the high-voltage circuit board under energized operation, a multi-band detection signal is injected into the circuit under test. The response current signal of the circuit under test is collected in real time by a high-precision current sensor. The phase offset of the response current signal in a specific characteristic frequency band is extracted. The occurrence of a micro short circuit fault is determined based on the dynamic comparison result of the phase offset and a preset threshold. At the same time, the electrical connection between the high-voltage main circuit and the detection system is isolated.

[0005] Preferably, the multi-band detection signal is composed of a sweep signal with a fundamental frequency of 1kHz to 10MHz, the spacing between adjacent frequency bands is configured in a non-linear increasing manner, and the dwell time of each frequency band is negatively correlated with the current high voltage circuit operating voltage.

[0006] Preferably, environmental parameter compensation is performed before signal injection, real-time acquisition of circuit board temperature distribution data and ambient humidity data is performed, and the amplitude gain coefficient of the detection signal is dynamically adjusted. The compensation formula is as follows:

[0007] Where α is the temperature compensation factor and β is the humidity compensation factor.

[0008] Preferably, the high-precision current sensor has a resolution of 0.1 microamperes, adopts a differential fluxgate structure design, controls the spatial distance between the sensor probe and the conductor under test within the range of 3 ± 0.5 mm, and applies an active electromagnetic shielding layer.

[0009] Preferably, the phase offset is extracted using an improved phase-locked loop technology, in which a digital adaptive filter is cascaded after a traditional phase detector, and the cutoff frequency of the filter is adjusted in real time according to the opening of the vehicle's accelerator pedal.

[0010] Preferably, a load status monitoring mechanism is introduced during the fault diagnosis stage. When a change in the switching frequency of the motor controller power module is detected to exceed 10%, the detection cycle is automatically delayed until the power status stabilizes and the detection process is restarted.

[0011] Preferably, the electrical isolation adopts a four-level protection architecture, including an optocoupler isolation layer, a microwave wireless transmission layer, a Faraday electromagnetic shielding layer, and a ceramic dielectric isolation layer, with an isolation withstand voltage level of DC 3000V / min.

[0012] Preferably, a dynamic frequency band selection logic is set, which prioritizes the 1 / 2 harmonic frequency band of the current high voltage circuit operating frequency as the main detection frequency band. When the signal-to-noise ratio of this frequency band is lower than 20dB, it automatically switches to the 3 / 2 harmonic frequency band.

[0013] Preferably, a self-calibration procedure is performed after each detection cycle, which generates a reference signal by injecting a standard reference resistor network to correct the zero-point drift error and gain error of the current sensor.

[0014] Preferably, the detection results are deeply integrated with the battery management system. When a micro short circuit risk is detected three times in a row, the high-voltage circuit pre-charge resistor connection command is automatically triggered and the maximum output power is reduced to 60% of the rated value.

[0015] The above-described solution of the present invention has at least the following beneficial effects: A 1kHz-10MHz sweep frequency signal is injected into the circuit under test. By utilizing the difference in sensitivity to capacitive / resistive short-circuit faults at different frequencies, the detection blind zone of a single frequency band is overcome. The response current is captured by a 0.1μA differential fluxgate sensor, and the phase shift of a specific frequency band is extracted using an improved phase-locked loop. When a micro-short circuit causes a change in the circuit's capacitive reactance, the phase shift is more significant than the change in current amplitude. A phase shift-fault degree mapping model is established, and a fault alarm is triggered when the detected value exceeds a preset dynamic threshold (adjusted according to temperature or humidity compensation). A quadruple isolation of optocoupler + microwave transmission + Faraday shielding + ceramic dielectric is used to ensure the safe decoupling of the detection system from the high-voltage main circuit under a withstand voltage of 3000V. Phase offset detection enables micro-short circuit identification sensitivity to reach 50 microamps, while traditional methods have a minimum sensitivity of 200 microamps. It also breaks through the problem of live detection, shortening the detection cycle to 0.5 seconds per test without interrupting vehicle operation. Multi-band scanning combined with dynamic frequency band selection effectively suppresses motor controller switching noise. The four-level isolation architecture achieves physical and electrical dual isolation between the detection system and the high-voltage main circuit, with a withstand voltage rating of DC 3000V / min. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a flowchart of an online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles, provided in an embodiment of the present invention.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "circumferential," and "radial," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] The following describes in detail, with reference to the accompanying drawings, the online detection method for micro-short circuits of high-voltage circuit boards in new energy vehicles according to an embodiment of the present invention.

[0025] Please see Figure 1 In this embodiment, the method includes: injecting multi-band detection signals into the circuit under test while the high-voltage circuit board is energized; acquiring the response current signal of the circuit under test in real time through a high-precision current sensor; extracting the phase offset of the response current signal in a specific characteristic frequency band; determining the occurrence of a micro short circuit fault based on the dynamic comparison result of the phase offset and a preset threshold; and simultaneously isolating the electrical connection between the high-voltage main circuit and the detection system. A 1kHz-10MHz sweep frequency signal is injected into the circuit under test. By utilizing the difference in sensitivity to capacitive / resistive short-circuit faults at different frequencies, the detection blind zone of a single frequency band is overcome. The response current is captured by a 0.1μA differential fluxgate sensor, and the phase shift of a specific frequency band is extracted using an improved phase-locked loop. When a micro-short circuit causes a change in the circuit's capacitive reactance, the phase shift is more significant than the change in current amplitude. A phase shift-fault degree mapping model is established, and a fault alarm is triggered when the detected value exceeds a preset dynamic threshold (adjusted according to temperature or humidity compensation). A quadruple isolation of optocoupler + microwave transmission + Faraday shielding + ceramic dielectric is used to ensure the safe decoupling of the detection system from the high-voltage main circuit under a withstand voltage of 3000V. Phase offset detection enables micro-short circuit identification sensitivity to reach 50 microamps, while traditional methods have a minimum sensitivity of 200 microamps. It also breaks through the problem of live detection, shortening the detection cycle to 0.5 seconds per test without interrupting vehicle operation. Multi-band scanning combined with dynamic frequency band selection effectively suppresses motor controller switching noise. The four-level isolation architecture achieves physical and electrical dual isolation between the detection system and the high-voltage main circuit, with a withstand voltage rating of DC 3000V / min.

[0026] In this embodiment, the multi-band detection signal consists of a sweep signal with a fundamental frequency of 1kHz to 10MHz. The spacing between adjacent frequency bands is configured in a non-linear increasing manner, and the dwell time of each frequency band is negatively correlated with the current high-voltage circuit operating voltage. Multi-band detection signal generation and execution I. Configuration of Sweep Frequency Signal Generator A digital frequency synthesizer (DDS) is used to generate a sweep frequency signal with a fundamental frequency of 1kHz-10MHz, dividing the entire frequency domain into 50 detection frequency bands; The frequency band spacing is set according to an exponential increasing pattern: in the 1-100kHz low-frequency range, equal intervals of 10kHz are used (10 segments in total); in the 100kHz-1MHz mid-frequency range, the spacing increases in 50kHz increments (18 segments); and in the 1-10MHz high-frequency range, a base spacing of 200kHz × 2 is used. n Nonlinear allocation (22 segments); This configuration makes the high-frequency band width 32 times that of the low-frequency band, effectively adapting to changes in the distributed parameters of the circuit.

[0027] II. Voltage Adaptive Dwell Control Real-time acquisition of high-voltage bus voltage U via Battery Management System (BMS) bus Define a negative correlation function between residence time τ and voltage:

[0028] When U is detected bus At 400V (vehicle start-up phase), the dwell time of each frequency band is 50ms. WhenU bus When the voltage is increased to 820V (high-speed cruise), the dwell time is automatically reduced to 24.8ms. This design ensures that the detection cycle is reduced by 60% under high-voltage conditions, preventing overheating of power devices.

[0029] III. Signal Injection Execution Example During the interval between IGBT switching operations in the motor controller (synchronized via the gate drive signal), a detection signal is injected between the positive and negative terminals of the DC-Link via a capacitive coupler: Band 1: Starting frequency 1kHz, lasting 50ms (U bus =400V). Band 15: Center frequency 450kHz, dwell time 41ms (U bus =600V). Band 37: Cutoff frequency 7.2MHz, dwell time 28ms (U bus =750V).

[0030] In this embodiment, environmental parameter compensation is performed before signal injection. Real-time data on circuit board temperature distribution and ambient humidity are collected, and the amplitude gain coefficient of the detection signal is dynamically adjusted. The compensation formula is as follows:

[0031] Where α is the temperature compensation factor and β is the humidity compensation factor; Implementation of dynamic environmental compensation system I. Multi-source environmental data acquisition Temperature monitoring: PT1000 thin-film temperature sensors are embedded in three key locations on the high-voltage circuit board: the power module (IGBT), the DC-Link capacitor area, and the copper busbar connector, with a sampling frequency of 10Hz; Humidity monitoring: A capacitive humidity sensor (accuracy ±2%RH) is installed inside the battery pack pressure relief valve and is kept at the same potential as the circuit board; Data fusion: The weighted average algorithm is used to calculate the comprehensive environmental parameters, with the power module temperature having a weighting coefficient of 0.6 (high thermal sensitivity area) and 0.2 for other areas.

[0032] II. Real-time parameters of the compensation formula The compensation factor was determined based on a 3000-hour accelerated aging test: Temperature compensation factor α = 0.0038 / ℃ (corresponding value to the thermal expansion coefficient of silicon-based materials); Humidity compensation factor β = 0.0045 / %RH (measured value of PCB moisture absorption rate). Reference gain = 1.25V / A (calibrated under standard conditions of 25℃ / 40%RH).

[0033] Example of real-time compensation calculation: When the power module temperature is detected to be T=105℃ and the ambient humidity is RH=95%:

[0034] III. Compensation Implementation Process The compensation process is initiated 200ms before the detection signal is injected. 1. Read all sensor data and remove transient interference values ​​(>3σ deviation data); 2. Calculate the current overall temperature T comp = (T IGBT ×0.6 + T Cap ×0.2 + T Busbar ×0.2); 3. Place T comp Substitute RH into the compensation formula to generate the gain coefficient; 4. Adjust the PGA (Programmable Gain Amplifier) ​​of the detection signal amplifier to achieve dynamic calibration of the signal amplitude.

[0035] In this embodiment, the high-precision current sensor has a resolution of 0.1 microamperes, adopts a differential fluxgate structure design, the spatial distance between the sensor probe and the wire being measured is controlled within the range of 3 ± 0.5 mm, and an active electromagnetic shielding layer is applied. Implementation of Differential Fluxgate Sensor System Taking an 800V SiC motor controller high-voltage circuit board as the application object, the detection circuit carries a current of 0-600A DC. The specific implementation process is as follows: I. Sensor Structure Deployment Probe architecture: It adopts a dual-core differential structure, with the main magnetic core (permalloy 1J85) and the compensation magnetic core (nanocrystalline ribbon FT-3M) arranged symmetrically. The excitation coil is supplied with a 125kHz triangular wave excitation current (peak-to-peak ±15mA). Spacing control: Insulating ceramic positioning grooves (Al2O3 purity 99.6%) are machined on the surface of the high-voltage copper busbar to ensure that the spacing between the sensor probe and the conductor is constant at 3.0±0.05mm (calibrated online by a laser rangefinder). Electromagnetic shielding: The probe is wrapped with a three-layer shielding structure: the inner layer is a 0.1mm thick permalloy foil (μr=80,000), the middle layer is a copper mesh (200 mesh), and the outer layer is coated with a conductive ceramic coating (volume resistivity 10Ω·cm).

[0036] II. Implementation of Key Parameters

[0037] III. Installation and Positioning Implemented on the DC-Link positive copper busbar of the motor controller: 1. Remove the oxide layer from the surface of the copper busbar and spray a 0.3mm thick insulating ceramic coating (withstand voltage >5kV); 2. Install the sensor base and fix the probe position using ceramic positioning pins; 3. Use a laser interferometer to measure the air gap distance and adjust it to 2.98mm (target value 3.0mm); 4. Apply a torque of 25 N·m to tighten the stainless steel fasteners to ensure that the displacement is <5 μm under vibration conditions.

[0038] In this embodiment, the phase offset is extracted using an improved phase-locked loop technology, in which a digital adaptive filter is cascaded after a traditional phase detector, and the cutoff frequency of the filter is adjusted in real time according to the opening of the vehicle's accelerator pedal. Phase offset dynamic extraction system implementation Using an 800V permanent magnet synchronous motor controller as the application platform, the high-voltage circuit board operates at a frequency range of 2-20kHz. The specific implementation process is as follows: 1. Hardware architecture deployment Phase detector: A traditional phase-locked loop is constructed using the ADF4158 frequency synthesis chip, with a reference signal input range of 1kHz-10MHz; Adaptive filter: A variable bandwidth FIR filter implemented by cascading a Xilinx 7Z035 FPGA at the phase detector output; Filter order: 128th order Hamming window design; coefficient update rate: 10μs / time. Accelerator pedal interface: Real-time acquisition of pedal opening signal via CAN bus (resolution accuracy 0.1%).

[0039] 2. Dynamic frequency control mechanism

[0040] Application example: When a vehicle accelerates rapidly (opening degree from 40% to 85% / 500ms): t=0ms: Opening degree 40% → f c =2kHz; t=200ms: Opening degree 65% →f c =4kHz×2 0.125 =4.36kHz; t=500ms: Opening degree 85% →f c =4kHz×2 0.625 =6.73kHz.

[0041] III. Fault Diagnosis Comparison Test Testing for the same capacitive micro-short circuit fault (equivalent capacitance between PCB layers 120pF):

[0042] IV. Anti-saturation control When IGBT switching transient interference (di / dt>100A / μs) is detected: 1. Automatically activate the anti-saturation algorithm; 2. Temporarily insert a zero-point compensator:

[0043] 3. Reduce the filter gain to 30% of its normal value; 4. The original parameters are restored within 10μs after the interference disappears.

[0044] In this embodiment, a load status monitoring mechanism is introduced during the fault diagnosis stage. When the switching frequency of the motor controller power module is detected to change by more than 10%, the detection cycle is automatically delayed until the power status stabilizes and the detection process is restarted. Implementation of Load Fluctuation Adaptive Detection System Using a high-voltage control system for a dual-motor, four-wheel-drive pure electric SUV as the application platform, the switching frequency range of the front axle motor controller is 5-20kHz, and that of the rear axle controller is 8-25kHz. The specific implementation process is as follows: I. Power Condition Monitoring System Signal acquisition points: 1. IGBT gate drive signal (captured via a high-voltage differential probe); 2. SiC MOSFET switching node voltage (using a 1GHz bandwidth active probe).

[0045] Frequency variation calculation:

[0046] The baseline frequency fbaseline is taken from the average value within 10 seconds after the vehicle starts.

[0047] II. Delayed Trigger Logic Execution When any controller is detected hour: 1. Immediately interrupt the current detection cycle; 2. Start the countdown timer:

[0048] 3. Monitor the power stability flag (bus voltage fluctuation <±3% for 5ms); 4. Re-inject the detection signal after the conditions are met.

[0049] Example illustration (rapid acceleration): The switching frequency of the rear axle controller was changed from 12kHz to 15.8kHz. Interruption micro-short circuit detection; Calculate delay time ; Bus voltage fluctuation <1.2% (compliant); Restart the detection process.

[0050] III. Multi-level fluctuation identification mechanism

[0051] In this embodiment, the electrical isolation adopts a four-level protection architecture, including an optocoupler isolation layer, a microwave wireless transmission layer, a Faraday electromagnetic shielding layer, and a ceramic dielectric isolation layer, with an isolation withstand voltage level of DC 3000V / min; Implementation of Level 4 Electrical Isolation System Taking an 800V silicon carbide all-in-one electric drive system as the application example, the peak operating voltage of the high-voltage circuit board is 1200V. The specific implementation process is as follows: I. Deployment of a Level 4 Isolation Architecture

[0052] II. Collaborative Workflow 1. Signal acquisition stage: The high-precision current sensor signal is physically isolated through a ceramic dielectric layer (L4); Digital signals are transmitted via a 24 GHz carrier frequency through the microwave wireless layer (L2).

[0053] 2. Data Processing Stage The received signal enters the control segment through the optocoupler layer (L1); The entire module is placed inside a Faraday cage (L3) (grid size λ / 20@1GHz).

[0054] 3. Fault Protection Phase When a micro short circuit is detected, the L1 layer optocoupler cuts off the control loop; The L4 layer ceramic dielectric withstands all high-pressure impacts.

[0055] In this embodiment, dynamic frequency band selection logic is set to prioritize the 1 / 2 harmonic frequency band of the current high voltage circuit operating frequency as the main detection frequency band. When the signal-to-noise ratio of this frequency band is lower than 20dB, it automatically switches to the 3 / 2 harmonic frequency band. Implementation of dynamic frequency band switching system Using an 800V flat wire motor high-voltage control system as the application platform, with a fundamental frequency range of 1.8-15kHz, the specific implementation process is as follows: I. Harmonic Frequency Band Mapping Mechanism Harmonic frequency band mapping mechanism Main detection frequency band: Real-time acquisition of the motor controller PWM frequency Calculate the main detection frequency band:

[0056] Backup detection frequency band:

[0057] Frequency band width: dynamically set to ±7.5% of the fundamental frequency (anti-frequency deviation design).

[0058] Application example (urban traffic congestion) Motor running at low speed: ; High-speed cruise .

[0059] II. Signal-to-noise ratio triggered switching logic

[0060] III. Multi-condition performance verification Then click on the controller to switch the frequency sudden change scenario (10kHz→18kHz / 100ms):

[0061] IV. Anti-saturation design When third harmonic distortion (THD>8%) is detected: 1. Automatic insertion of notch filters:

[0062] 2. Center frequency locked to ; 3. Stopband attenuation > 46dB.

[0063] In this embodiment, a self-calibration procedure is performed after each detection cycle. A reference signal is generated by injecting a standard reference resistor network to correct the zero-point drift error and gain error of the current sensor. Implementation of online self-calibration system Using an 800V integrated electric drive system as the application platform, the high-voltage circuit board integrates 12 detection channels. The specific implementation process is as follows: I. Standard Reference Network Design Topology: Star resistor network (floating center point design); Reference resistor: High-stability metal foil resistor (5kΩ±0.001%, temperature drift±1ppm / ℃); Fault simulation branch:

[0064] Switching device: Vacuum relay matrix (switching time <0.5ms, withstand voltage 3kV); Calibration accuracy:

[0065] II. Calibration Execution Process Triggering timing: After each detection cycle ends + system power-on initialization; Three-level calibration mode:

[0066] Signal injection: A 1mA@10kHz detection signal (equivalent to a 50μA micro short circuit) is injected into the reference network via a high-voltage MOSFET.

[0067] III. Core of the Calibration Algorithm Zero-point drift compensation:

[0068] Gain error correction:

[0069] Nonlinear correction:

[0070] In this embodiment, the detection results are deeply integrated with the battery management system. When a micro-short circuit risk is detected three times consecutively, a high-voltage circuit pre-charge resistor connection command is automatically triggered, and the maximum output power is reduced to 60% of the rated value. Battery Management System Collaborative Protection System Implementation Taking a 100kWh solid-state battery pack and an 800V SiC electric drive platform as the application example, the specific implementation process is as follows: I. Logic of Level 3 Risk Assessment

[0071] Threshold settings: fundamental frequency band: 5° (corresponding to 50μA micro short circuit), third harmonic frequency band: 1.2° (corresponding to 20μA capacitive leakage).

[0072] II. Pre-charge control execution process Resistor connection: Control the high-voltage contactor K1 to disconnect the main circuit; Close the pre-charge contactor K2 (connect a 50Ω / 500W negative temperature coefficient resistor); Access time:

[0073] Power Limitation: Torque limiting command sent via CAN bus:

[0074] Simultaneously reduce the DC-DC output to 72V (originally 84V).

[0075] III. Implementation of Key Parameters

[0076] IV. Real-world vehicle troubleshooting cases Condensation causes inter-board creepage faults: Three consecutive Δθ anomalies were detected (7.3° / 6.8° / 7.5°@3.2kHz); Within 12ms, the system executes the following: disconnecting the main contactor, connecting the pre-charge resistor, limiting the drive power to 180kW (originally 300kW), and activating the bottom heating film of the battery pack (dehumidification mode). Fault location: Motor controller PCB area A17; On-site measurements and verification by maintenance personnel: Insulation resistance: 48kΩ (standard >1MΩ), leakage current: 82μA.

[0077] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0078] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles, characterized in that, include: In the high-voltage circuit board under energized operation, a multi-band detection signal is injected into the circuit under test. The response current signal of the circuit under test is collected in real time by a high-precision current sensor. The phase offset of the response current signal in a specific characteristic frequency band is extracted. The occurrence of a micro short circuit fault is determined based on the dynamic comparison result of the phase offset and a preset threshold. At the same time, the electrical connection between the high-voltage main circuit and the detection system is isolated.

2. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 1, characterized in that, The multi-band detection signal consists of a sweep signal with a fundamental frequency of 1kHz to 10MHz. The spacing between adjacent frequency bands is configured in a non-linear incrementing manner, and the dwell time of each frequency band is negatively correlated with the current operating voltage of the high-voltage circuit.

3. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 2, characterized in that, Before signal injection, environmental parameter compensation is performed. Real-time data on circuit board temperature distribution and ambient humidity are collected to dynamically adjust the amplitude gain coefficient of the detection signal. The compensation formula is as follows: ； Where α is the temperature compensation factor and β is the humidity compensation factor.

4. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 1, characterized in that, The high-precision current sensor has a resolution of 0.1 microamperes, adopts a differential fluxgate structure design, controls the spatial distance between the sensor probe and the conductor being measured within the range of 3 ± 0.5 mm, and applies an active electromagnetic shielding layer.

5. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 1, characterized in that, The phase offset is extracted using an improved phase-locked loop (PLL) technology, which cascades a digital adaptive filter after a traditional phase detector. The cutoff frequency of the filter is adjusted in real time according to the vehicle's accelerator pedal opening.

6. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 1, characterized in that, A load status monitoring mechanism is introduced during the fault diagnosis phase. When the switching frequency of the motor controller power module is detected to change by more than 10%, the detection cycle is automatically delayed until the power status stabilizes and the detection process is restarted.

7. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 1, characterized in that, The electrical isolation adopts a four-level protection architecture, including an optocoupler isolation layer, a microwave wireless transmission layer, a Faraday electromagnetic shielding layer, and a ceramic dielectric isolation layer, with an isolation withstand voltage level of DC 3000V / min.

8. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 2, characterized in that, The dynamic frequency band selection logic is set to prioritize the 1 / 2 harmonic frequency band of the current high voltage circuit operating frequency as the main detection frequency band. When the signal-to-noise ratio of this frequency band is lower than 20dB, it automatically switches to the 3 / 2 harmonic frequency band.

9. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 1, characterized in that, After each detection cycle, a self-calibration procedure is performed, which generates a reference signal by injecting a standard reference resistor network to correct the zero-point drift error and gain error of the current sensor.

10. The online detection method for micro-short circuits on high-voltage circuit boards of new energy vehicles according to claim 1, characterized in that, The detection results are deeply integrated with the battery management system. When a micro short circuit risk is detected three times in a row, the high-voltage circuit pre-charge resistor connection command is automatically triggered and the maximum output power is reduced to 60% of the rated value.

Images