Hybrid vehicle system multi-working condition electromagnetic interference test method

Abstract

The application provides a hybrid power system multi-working condition electromagnetic interference test method, which is based on a variety of typical system operation working conditions to design a working condition test sequence, and performs single or related time domain and frequency domain tests on the conduction current of high and low voltage wire harnesses in various working conditions and working condition switching scenes. The results obtained by the test can effectively extract the electromagnetic interference characteristics, conduction coupling path and strength corresponding to the specific working condition, and on this basis, the system level electromagnetic compatibility optimization design can better meet the needs of vehicle actual operation.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic compatibility testing technology, specifically relating to a method for testing conducted interference in cables of a vehicle hybrid power system under multiple operating conditions. Background Technology

[0002] With the increasing trend towards higher voltage, higher frequency, and higher integration in automotive electric drive and hybrid systems, the electromagnetic compatibility (EMC) issues faced by vehicles are becoming increasingly severe. Compared to the past, the amplitude, bandwidth, and complexity of conducted and radiated disturbances have significantly increased, easily leading to serious consequences such as communication anomalies, sensor signal distortion, and even controller failures. Therefore, it is necessary to accurately characterize and suppress the coupling disturbances between high- and low-voltage circuits within complex vehicle systems. However, existing EMC testing for new energy vehicles still focuses on simulations in experimental environments. The test benches and models often fail to accurately reflect the actual operating conditions of the onboard electric drive system. Furthermore, experiments are mostly conducted on single devices or specific coupling paths, neglecting comprehensive EMC analysis of highly integrated power systems. In addition, existing technologies lack in-depth research on the complex coupling characteristics between high- and low-voltage circuits in vehicles, and there are few solutions that can effectively capture the time-domain transient disturbance characteristics and low-frequency coupling features of the system during dynamic operating condition switching. This severely restricts the comprehensive understanding and accurate modeling of the high- and low-voltage coupling mechanisms within the system (especially its time-varying characteristics and low-frequency conduction paths). Therefore, how to overcome the shortcomings of existing technologies and realize a multi-condition electromagnetic interference testing method for vehicles that includes the coupling characteristics between high and low voltage circuits is an urgent technical problem that needs to be solved in this field. Summary of the Invention

[0003] In view of this, and to address the technical problems existing in this field, the present invention provides a multi-condition electromagnetic interference testing method for automotive hybrid power systems, specifically including the following steps:

[0004] Step 1: Build a test platform for the specific hybrid power system, including: generator, generator controller, drive motor, motor controller, electromechanical coupler, electromechanical transmission controller (TCU), oil pump motor controller, low-voltage (LV) power supply 1, low-voltage (LV) power supply 2, low-voltage (LV) power supply 3, repeater, host computer, and high-voltage power harnesses (such as high-voltage DC bus, motor phase lines) and low-voltage control / signal harnesses (such as low-voltage power lines, CAN bus, resolver cable, sensor harness, solenoid valve harness) required for the normal operation of each component; and set up time-domain and frequency-domain current testing and analysis devices.

[0005] Step 2: Set the different operating conditions and system working status to be tested;

[0006] Step 3: Under each set operating condition and working state, select the key high-voltage harness and low-voltage harness to be analyzed and perform time-domain and frequency-domain tests respectively; and, under a specific key operating condition, simultaneously perform the corresponding time-domain and frequency-domain tests on the key high-voltage harness and low-voltage harness.

[0007] Step 4: Based on the test results obtained in Step 3, perform comparative analysis of the time-domain and frequency-domain characteristics of the conducted current of the same cable under different operating conditions, as well as correlation analysis of the time-domain and frequency-domain characteristics of the high- and low-voltage harness currents at the moment of switching between different operating conditions; based on these analysis results, determine the characteristics and coupling strength of the electromagnetic interference high- and low-voltage coupling paths corresponding to different operating conditions, and predict the interference risks that may be caused by electromagnetic interference high- and low-voltage coupling under different operating conditions.

[0008] Step 5: Based on the test and analysis results and risk prediction results obtained in Steps 3 and 4, determine the correlation between each component in the hybrid power system and conducted interference under different operating conditions, and perform corresponding system-level electromagnetic compatibility design optimization.

[0009] Furthermore, in step one, the testing and analysis device specifically employs an oscilloscope for time-domain measurements, a spectrum analyzer for frequency-domain measurements, an RF current probe for broadband conducted current measurements, and a high-current probe for capturing low-frequency transient currents and high-amplitude waveforms. The RF current probe and the high-current probe are respectively clamped onto the high-voltage or low-voltage cable under test and connected to the oscilloscope and the spectrum analyzer respectively.

[0010] Furthermore, in step two, the following test conditions and working states are specifically set:

[0011] (1) The system is supplied with only low voltage (such as a 24V system);

[0012] (2) The system is under high voltage (such as a 900V system) and the drive motor controller is not turned on (IGBT is not working);

[0013] (3) The system is under high voltage and the drive motor controller is open (IGBT is working);

[0014] (4) Drive the motor to idle at a specific speed (e.g., 1000rpm, 3000rpm, 5000rpm);

[0015] (5) Drive motor running under load (e.g., 3000rpm, 100Nm);

[0016] (6) Only the generator and oil pump motor operate in the system;

[0017] (7) The drive motor, generator and oil pump motor work simultaneously (integrated commissioning mode).

[0018] Furthermore, in step three, the following test procedures are specifically performed for each set of working conditions:

[0019] (1) Select key high-voltage and wiring harnesses, including high-voltage DC positive / negative lines and motor phase lines, as well as key low-voltage wiring harnesses, including controller low-voltage power supply lines, CAN bus, and sensor lines; use a high-current probe and oscilloscope to obtain transient conduction current and its characteristic parameters such as peak current, pulse width, rise / fall time, and repetition frequency on individual wiring harnesses; capture transient interference caused by dynamic processes such as switching actions and working state switching;

[0020] (2) Use an RF current probe and a spectrum analyzer to obtain the conducted disturbance current spectrum characteristics of the key harness in a wide bandwidth, including peak, quasi-peak, average and harmonic amplitudes.

[0021] (3) Under the selected specific critical operating conditions, the above time domain and frequency domain tests were performed simultaneously on the high-voltage wiring harness and the sensitive low-voltage wiring harness, including the CAN bus and low-voltage power lines, and the synchronous test time was recorded.

[0022] Furthermore, in step four, the following analysis process is specifically performed using the test results from step three:

[0023] (1) Under different operating conditions such as high voltage switching, no-load / load, single unit / joint commissioning, etc., compare the time domain characteristics of the same wire harness, including transient amplitude, waveform changes, etc., as well as the frequency domain characteristics, including spectrum distribution, amplitude changes at specific frequency points, harmonic component changes, etc.

[0024] (2) Perform the following high-low voltage correlation analysis on high-voltage, high-power components, including drive motor controllers and generator controllers, during different operating conditions and instantaneous switching between operating conditions:

[0025] ① Determine whether a specific time-domain transient event (such as a switch spike) occurring on a high-voltage line harness is temporally correlated with an abnormal transient or noise occurring on a low-voltage line harness;

[0026] ② Determine whether the significant frequency domain interference components (such as specific switching frequency harmonics, broadband noise bands) appearing on the high-voltage line harness are correlated in the frequency domain with the significant increase in the interference amplitude of the corresponding frequency band on the low-voltage line harness;

[0027] (3) Based on the time-domain and frequency-domain correlation analysis results of the high-voltage and low-voltage circuits, the key coupling path characteristics of high-voltage interference coupled to low-voltage sensitive circuits are determined, and the coupling strength is evaluated using parameters including the dB value of interference rise on the low-voltage line. Based on the coupling path characteristics and coupling strength analysis results under different operating conditions, the electromagnetic interference coupling mechanism between high-voltage and low-voltage circuits under specific operating conditions and the interference risk that it may cause to low-voltage circuits (such as communication and control signals) are predicted.

[0028] The multi-condition electromagnetic interference testing method for vehicle hybrid power systems provided by the present invention designs a test sequence based on various typical system operating conditions, and performs individual or related time-domain and frequency-domain tests on the high and low voltage wiring harnesses in the system under various operating conditions and operating condition switching scenarios. The test results can effectively extract the electromagnetic interference characteristics, conducted coupling paths and strengths corresponding to specific operating conditions. Based on this, system-level electromagnetic compatibility optimization design can be carried out, which can better meet the actual operating needs of vehicles. Attached Figure Description

[0029] Figure 1 This is a diagram showing the optional connection structure of the high-voltage wiring harness in the test platform constructed in the method provided by this invention;

[0030] Figure 2 This is a diagram showing the optional connection structure of the low-voltage wiring harness in the test platform built in the method provided by the present invention. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The multi-condition electromagnetic interference testing method for automotive hybrid power systems provided by this invention specifically includes the following steps:

[0033] Step 1: Build a test platform for the specific hybrid power system, including: generator, generator controller, drive motor, motor controller, electromechanical coupler, electromechanical transmission controller (TCU), oil pump motor controller, low-voltage (LV) power supply 1, low-voltage (LV) power supply 2, low-voltage (LV) power supply 3, repeater, host computer, and high-voltage power harnesses (such as high-voltage DC bus, motor phase lines) and low-voltage control / signal harnesses (such as low-voltage power lines, CAN bus, resolver cable, sensor harness, solenoid valve harness) required for the normal operation of each component; and set up time-domain and frequency-domain current testing and analysis devices. Figure 1 , 2 The diagram shows a high-voltage and low-voltage wiring harness connection structure constructed based on an example of the present invention;

[0034] Step 2: Set the different operating conditions and system working status to be tested;

[0035] Step 3: Under each set operating condition and working state, select the key high-voltage harness and low-voltage harness to be analyzed and perform time-domain and frequency-domain tests respectively; and, under a specific key operating condition, simultaneously perform the corresponding time-domain and frequency-domain tests on the key high-voltage harness and low-voltage harness.

[0036] Step 4: Based on the test results obtained in Step 3, perform comparative analysis of the time-domain and frequency-domain characteristics of the conducted current of the same cable under different operating conditions, as well as correlation analysis of the time-domain and frequency-domain characteristics of the high- and low-voltage harness currents at the moment of switching between different operating conditions; based on these analysis results, determine the characteristics and coupling strength of the electromagnetic interference high- and low-voltage coupling paths corresponding to different operating conditions, and predict the interference risks that may be caused by electromagnetic interference high- and low-voltage coupling under different operating conditions.

[0037] Step 5: Based on the test and analysis results and risk prediction results obtained in Steps 3 and 4, determine the correlation between each component in the hybrid power system and conducted interference under different operating conditions, and perform corresponding system-level electromagnetic compatibility design optimization.

[0038] In a preferred embodiment of the present invention, the testing and analysis device in step one specifically employs an oscilloscope for time-domain measurement, a spectrum analyzer for frequency-domain measurement, an RF current probe for broadband conduction current measurement, and a high-current probe for capturing low-frequency transient current and high-amplitude waveforms; the RF current probe and the high-current probe are respectively clamped on the high-voltage or low-voltage cable to be tested, and respectively connected to the oscilloscope and the spectrum analyzer.

[0039] In a preferred embodiment of the present invention, the following test conditions and working states are specifically set in step two:

[0040] (1) The system is supplied with only low voltage (such as a 24V system);

[0041] (2) The system is under high voltage (such as a 900V system) and the drive motor controller is not turned on (IGBT is not working);

[0042] (3) The system is under high voltage and the drive motor controller is open (IGBT is working);

[0043] (4) Drive the motor to idle at a specific speed (e.g., 1000rpm, 3000rpm, 5000rpm);

[0044] (5) Drive motor running under load (e.g., 3000rpm, 100Nm);

[0045] (6) Only the generator and oil pump motor operate in the system;

[0046] (7) The drive motor, generator and oil pump motor work simultaneously (integrated commissioning mode).

[0047] In a preferred embodiment of the present invention, step three involves performing the following test process for each set operating condition:

[0048] (1) Select key high-voltage and wiring harnesses, including high-voltage DC positive / negative lines and motor phase lines, as well as key low-voltage wiring harnesses, including controller low-voltage power supply lines, CAN bus, and sensor lines; use a high-current probe and oscilloscope to obtain transient conduction current and its characteristic parameters such as peak current, pulse width, rise / fall time, and repetition frequency on individual wiring harnesses; capture transient interference caused by dynamic processes such as switching actions and working state switching;

[0049] (2) Use an RF current probe and a spectrum analyzer to obtain the conducted disturbance current spectrum characteristics of the key harness in a wide bandwidth, including peak, quasi-peak, average and harmonic amplitudes.

[0050] (3) Under the selected specific critical operating conditions, the above time domain and frequency domain tests were performed simultaneously on the high-voltage wiring harness and the sensitive low-voltage wiring harness, including the CAN bus and low-voltage power lines, and the synchronous test time was recorded.

[0051] In a preferred embodiment of the present invention, the following analysis process is specifically performed in step four using the test results from step three:

[0052] (1) Under different operating conditions such as high voltage switching, no-load / load, single unit / joint commissioning, etc., compare the time domain characteristics of the same wire harness, including transient amplitude, waveform changes, etc., as well as the frequency domain characteristics, including spectrum distribution, amplitude changes at specific frequency points, harmonic component changes, etc.

[0053] (2) Perform the following high-low voltage correlation analysis on high-voltage, high-power components, including drive motor controllers and generator controllers, during different operating conditions and instantaneous switching between operating conditions:

[0054] ① Determine whether a specific time-domain transient event (such as a switch spike) occurring on a high-voltage line harness is temporally correlated with an abnormal transient or noise occurring on a low-voltage line harness;

[0055] ② Determine whether the significant frequency domain interference components (such as specific switching frequency harmonics, broadband noise bands) appearing on the high-voltage line harness are correlated in the frequency domain with the significant increase in the interference amplitude of the corresponding frequency band on the low-voltage line harness;

[0056] (3) Based on the time-domain and frequency-domain correlation analysis results of the high-voltage and low-voltage circuits, the key coupling path characteristics of high-voltage interference coupled to low-voltage sensitive circuits are determined, and the coupling strength is evaluated using parameters including the dB value of interference rise on the low-voltage line. Based on the coupling path characteristics and coupling strength analysis results under different operating conditions, the electromagnetic interference coupling mechanism between high-voltage and low-voltage circuits under specific operating conditions and the interference risk that it may cause to low-voltage circuits (such as communication and control signals) are predicted.

[0057] It should be understood that the sequence number of each step in the embodiments of the present invention does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for testing electromagnetic disturbance of a hybrid power system in multiple operating conditions for a vehicle, characterized in that: Specifically, the following steps are included: Step 1: Build a test platform for a specific hybrid power system, including: generator, generator controller, drive motor, motor controller, electromechanical coupler, electromechanical transmission controller, oil pump motor controller, low-voltage power supply, repeater, host computer, and high-voltage power harness and low-voltage control and signal harness required for the normal operation of each component; and set up time-domain and frequency-domain current testing and analysis devices. Step 2: Set the different operating conditions and system working status to be tested; Step 3: Under each set operating condition and working state, select the key high-voltage and low-voltage wiring harnesses to be analyzed and perform time-domain and frequency-domain tests respectively; and, under the selected specific key operating conditions, simultaneously perform the corresponding time-domain and frequency-domain tests on the key high-voltage and low-voltage wiring harnesses. Step 4: Utilize the test results from Step 3 to perform the following analysis: (1) Under different operating conditions including high voltage switching, no-load / load, single unit / joint commissioning, compare the time domain characteristics of the same harness including transient amplitude and waveform changes, as well as the frequency domain characteristics including spectrum distribution, amplitude changes at specific frequency points, and harmonic component changes. (2) Perform the following high-low voltage correlation analysis on high-voltage, high-power components, including drive motor controllers and generator controllers, under different operating conditions and during instantaneous switching between operating conditions: ① Determine whether a specific time-domain transient event occurring on a high-voltage line harness is temporally correlated with an abnormal transient or noise occurring on a low-voltage line harness; ② Determine whether the significant frequency domain interference components appearing on the high-voltage line harness are correlated in the frequency domain with the significant increase in the interference amplitude of the corresponding frequency band on the low-voltage line harness; (3) Based on the high-low voltage correlation analysis results of different time domains and frequency domains, the key coupling path characteristics of high voltage interference coupled to low voltage sensitive circuits are determined, and the coupling strength is evaluated using parameters including the dB value of interference rise on the low voltage line; based on the coupling path characteristics and coupling strength analysis results under different operating conditions, the electromagnetic interference coupling mechanism between high and low voltage circuits under specific operating conditions and its possible interference risk to low voltage circuits are predicted. Step 5: Based on the test and analysis results and risk prediction results obtained in Steps 3 and 4, determine the correlation between each component in the hybrid power system and conducted interference under different operating conditions, and perform corresponding system-level electromagnetic compatibility design optimization.

2. The method of claim 1, wherein: In step one, the testing and analysis apparatus specifically uses an oscilloscope for time-domain measurements, a spectrum analyzer for frequency-domain measurements, an RF current probe for broadband conducted current measurements, and a high-current probe for capturing low-frequency transient currents and high-amplitude waveforms. The RF current probe and the high-current probe are respectively clamped onto the high-voltage or low-voltage cable under test and connected to the oscilloscope and the spectrum analyzer respectively.

3. The method of claim 1, wherein: Step two involves setting the following test conditions and operating status: (1) The system is only supplied with low voltage; (2) The system is under high voltage and the drive motor controller is not open; (3) The system is under high voltage and the drive motor controller is open; (4) The drive motor idles at a specific speed; (5) The drive motor operates under load; (6) Only the generator and oil pump motor operate in the system; (7) Joint commissioning condition where the drive motor, generator and oil pump motor work simultaneously.

4. The method of claim 1, wherein: Step three involves performing the following test procedures for each set of operating conditions: (1) Select key high voltage and wiring harnesses including high voltage DC positive / negative lines and motor phase lines, as well as key low voltage wiring harnesses including controller low voltage power supply lines, CAN bus and sensor lines; use a high current probe and oscilloscope to obtain transient conduction current and its peak current, pulse width, rise / fall time and repetition frequency characteristic parameters on individual wiring harnesses; capture transient interference caused by dynamic processes including switching action and working state switching; (2) Use an RF current probe and a spectrum analyzer to obtain the conducted disturbance current spectrum characteristics of the key harness in a wide bandwidth, including peak, quasi-peak, average and harmonic amplitudes. (3) Under the selected specific critical operating conditions, the above time domain and frequency domain tests were performed simultaneously on the high voltage harness and the sensitive low voltage harness including the CAN bus and low voltage power line, and the synchronous test time was recorded.

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