Electric drive assembly shaft voltage test method and test system

Abstract

This invention relates to the field of electric drive assembly testing technology, specifically to a method and system for testing the shaft voltage of an electric drive assembly. The method includes the following steps: arranging grounding points on the electric drive assembly; arranging a first measuring point and a second measuring point at both ends of the motor shaft; controlling the on / off state of the eleven grounding points to achieve different testing modes; using a test bench to drive the electric drive assembly; recording the voltage of the first and second measuring points under each testing mode; analyzing the recorded voltages of the first and second measuring points under each testing mode to determine whether corresponding countermeasures need to be developed for the electric drive assembly. The electric drive assembly shaft voltage testing method of this application is simple, can accurately determine whether there is a risk of electro-corrosion in the bearings of the electric drive assembly, has extremely limited testing items, and allows for the development of corresponding countermeasures based on the risks, with minimal modifications and very low cost.

Description

Technical Field

[0001] This invention relates to the field of electric drive assembly testing technology, specifically to a method and system for testing shaft voltage of an electric drive assembly. Background Technology

[0002] With the development of new energy vehicles, high-voltage platforms (800V, 1000V) are gradually becoming a trend in their application. However, with the application of high-voltage platforms, the problem of bearing electro-corrosion in electric drive assemblies is becoming increasingly difficult to avoid.

[0003] Bearing galvanic corrosion occurs when shaft voltage breaks down the oil film in the bearing raceway between the inner and outer rings, causing corrosion of the raceway and steel balls. The shaft voltage amplitude is positively correlated with the controller input voltage, which explains why galvanic corrosion is more severe in 800V electric drive assemblies than in 400V assemblies. The impact of shaft voltage on the entire electric drive system is influenced by many factors, including controller logic, bearing type, lubricant characteristics, grounding ring effectiveness, and gearbox gears. Systematically measuring the shaft voltage amplitude, shaft current amplitude, and shaft voltage release path of the entire electric drive assembly is crucial for selecting the most economical and suitable solution to improve bearing galvanic corrosion during the design and development process.

[0004] Regardless of whether the electric drive assembly is oil-cooled or water-cooled, the kinematic viscosity coefficient of lubricating oil and grease is greatly affected by temperature, decreasing exponentially with increasing temperature. Therefore, during the operation of the electric drive assembly, a stable oil film often fails to form at the bearings, significantly impacting test results. Consequently, shaft voltage testing frequently requires various modifications to obtain easily analyzable shaft voltage data. Common shaft voltage testing and modification methods include:

[0005] 1. Three-in-one assembly test: Using a three-in-one assembly consisting of a motor, electronic control unit, and gearbox, measure the shaft voltage at the bearing position;

[0006] 2. Two-in-one assembly test: Without carrying the gearbox assembly, use the motor + electronic control to measure the shaft voltage at the motor bearing position;

[0007] 3. Bearing insulation modification test: Replace the motor bearing with a ceramic ball bearing and test the shaft voltage at the bearing position.

[0008] Shaft voltage testing often requires multiple rounds of modifications and testing to obtain the desired results. For example, after completing the initial assembly test, the assembly needs to be disassembled, a grounding ring installed, and then the shaft voltage change measured; or the metal bearing may be replaced with a ceramic ball bearing, and the shaft voltage change measured again. If the analysis and resolution of the gearbox-side bearing electro-corrosion problem is involved, the situation becomes even more complex. Each round of modification to the electric drive assembly takes several days, which is not only time-consuming but also can affect or even damage the assembly's condition, leading to discrepancies in test results. Summary of the Invention

[0009] The purpose of this application is to address the shortcomings of the aforementioned background technology and to provide a method and system for testing shaft voltage of an electric drive assembly.

[0010] The technical solution of this application is: a method for testing shaft voltage of an electric drive assembly, comprising the following steps.

[0011] Grounding points are arranged on the electric drive assembly, including a first grounding point and a second grounding point located at both ends of the motor shaft, a third grounding point and a fourth grounding point located at the bearings at both ends of the input shaft assembly, a fifth grounding point and a sixth grounding point located at the bearings at both ends of the intermediate shaft assembly, a seventh grounding point and an eighth grounding point located at the bearings at both ends of the differential assembly, a ninth grounding point and a tenth grounding point located at the bearings at both ends of the motor shaft, and an eleventh grounding point located on the main housing of the electric drive assembly.

[0012] A first measuring point and a second measuring point are arranged at both ends of the motor shaft.

[0013] Different test modes are achieved by controlling the on / off state of eleven grounding points. The electric drive assembly is driven by a bench, and the voltage of the first and second test points is recorded in each test mode.

[0014] Analyze the voltages of the first and second test points under each recorded test mode to determine whether corresponding countermeasures need to be formulated for the electric drive assembly.

[0015] According to the method for testing shaft voltage of an electric drive assembly provided in this application, the method of arranging grounding points on the electric drive assembly includes: arranging lead wires at each grounding point, one end of the lead wire passing through the main housing and entering the insulating base at the grounding point, connecting to the corresponding grounding point, and the other end connecting to the grounding wire, with a switch arranged on the lead wire.

[0016] According to the electric drive assembly shaft voltage testing method provided in this application, the method for controlling the on / off state of eleven grounding points to achieve different testing modes includes:

[0017] Mode 1: Disconnect the first and second grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages at the first and second measuring points as the voltage at the front end and rear end of the first motor, respectively.

[0018] Mode 2: Connect the ninth, tenth, and eleventh grounding points, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages at the first and second measuring points as the voltages at the front and rear ends of the second motor.

[0019] Mode 3: Disconnect the first, second, ninth, and tenth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages at the first and second measuring points as the front-end voltage and rear-end voltage of the third motor.

[0020] According to the electric drive assembly shaft voltage testing method provided in this application, the method for analyzing the recorded motor front-end shaft voltage and motor rear-end shaft voltage includes: if the waveforms of the first motor front-end voltage, the first motor rear-end voltage, the second motor front-end voltage, the second motor rear-end voltage, the third motor front-end voltage, and the third motor rear-end voltage are all common-mode waveforms, it is determined that the risk of electrical corrosion of the bearings of the current electric drive assembly is low, and no countermeasures need to be formulated.

[0021] If the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, and the second motor rear end voltage are all breakdown waveforms, and the waveforms of the third motor front end voltage and the third motor rear end voltage are common mode waveforms, it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the motor side. Further judgment based on the voltage is needed and corresponding countermeasures should be taken.

[0022] If the waveforms of the front-end voltage of the second motor and the rear-end voltage of the second motor are common-mode waveforms, and the waveforms of the front-end voltage of the first motor, the rear-end voltage of the first motor, the front-end voltage of the third motor, and the rear-end voltage of the third motor are breakdown waveforms, it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the gearbox side. Further judgment based on the voltage is needed and corresponding countermeasures should be taken.

[0023] If the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, the second motor rear end voltage, the third motor front end voltage, and the third motor rear end voltage are all breakdown waveforms, it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the gearbox side and the motor side. Further judgment and corresponding countermeasures are needed based on the voltage.

[0024] According to the shaft voltage testing method for an electric drive assembly provided in this application, when it is determined that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side and / or on the gearbox side, if the front voltage of the first motor, the rear voltage of the first motor, the front voltage of the second motor, the rear voltage of the second motor, the front voltage of the third motor, and the rear voltage of the third motor are all less than the allowable value of the shaft voltage, then it is determined that the current bearing has a low risk of electrical corrosion and no countermeasures need to be formulated; otherwise, it is necessary to further judge based on the voltage and make corresponding countermeasures.

[0025] According to the shaft voltage test method of the electric drive assembly provided in this application, when it is determined that there is a risk of electrical corrosion on the motor side of the bearing of the current electric drive assembly, if the front voltage of the first motor, the rear voltage of the first motor, the front voltage of the second motor, the rear voltage of the second motor, the front voltage of the third motor, and the rear voltage of the third motor are all less than the allowable value of the shaft voltage, the test mode four is performed; the test method of mode four is as follows: connect the first grounding point, the ninth grounding point, the tenth grounding point, and the eleventh grounding point, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly to run, and record the voltages of the first test point and the second test point as the front voltage of the fourth motor and the rear voltage of the fourth motor;

[0026] If both the front-end voltage and the rear-end voltage of the fourth motor are less than the allowable value of the shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the front end of the motor; otherwise, the test of mode five will be carried out.

[0027] The test method for mode five is as follows: connect the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly to run, and record the voltages at the first and second test points as the front voltage and rear voltage of the fifth motor.

[0028] If both the front-end voltage and the rear-end voltage of the fifth motor are less than the allowable shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the rear end of the motor; otherwise, the test of mode six will be performed.

[0029] The test method for Mode 6 is as follows: connect the first grounding point, the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly to run, and record the voltages at the first and second test points as the front voltage and rear voltage of the sixth motor.

[0030] If both the front-end voltage and the rear-end voltage of the sixth motor are less than the allowable shaft voltage, the electric drive assembly adopts the countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, the countermeasure is to replace all the bearings of the electric drive assembly with ceramic ball bearings or to use an insulating coating to insulate the bearings from the housing and shaft in contact with them.

[0031] According to the shaft voltage testing method for an electric drive assembly provided in this application, when it is determined that there is a risk of electro-corrosion on the gearbox side of the bearing of the current electric drive assembly, if the voltages of the front end of the first motor, the rear end of the first motor, the front end of the second motor, the rear end of the second motor, the front end of the third motor, and the rear end of the third motor are all less than the allowable shaft voltage value, a mode seven test is performed. The mode seven test method is as follows: connect the two sides of the switch corresponding to the first measuring point and the third grounding point, connect the two sides of the switch corresponding to the second measuring point and the fourth grounding point, disconnect the first grounding point, the second grounding point, the third grounding point, and the fourth grounding point, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first measuring point and the second measuring point as the voltages of the front end of the seventh input shaft and the voltage of the seventh input shaft. Input shaft rear end voltage; connect the first measuring point to the switch corresponding to the fifth grounding point on both sides, connect the second measuring point to the switch corresponding to the sixth grounding point on both sides, disconnect the first grounding point, second grounding point, fifth grounding point and sixth grounding point, connect the remaining grounding points, use a test bench to drive the electric drive assembly to run, and record the voltages of the first measuring point and the second measuring point as the front end voltage and the rear end voltage of the seventh intermediate shaft; connect the first measuring point to the switch corresponding to the seventh grounding point on both sides, connect the second measuring point to the switch corresponding to the eighth grounding point on both sides, disconnect the first grounding point, second grounding point, seventh grounding point and eighth grounding point, connect the remaining grounding points, use a test bench to drive the electric drive assembly to run, and record the voltages of the first measuring point and the second measuring point as the front end voltage and the rear end voltage of the seventh differential shaft;

[0032] If the voltage at the front end of the seventh input shaft, the voltage at the rear end of the seventh input shaft, the voltage at the front end of the seventh intermediate shaft, the voltage at the rear end of the seventh intermediate shaft, the voltage at the front end of the seventh differential shaft, and the voltage at the rear end of the seventh differential shaft are all less than the allowable value of the shaft voltage, then it is determined that the risk of electro-corrosion of the bearings at both ends of the axial direction of the current electric drive assembly input shaft assembly is low, and no countermeasures are required; otherwise, test mode eight is performed.

[0033] The test method for Mode 8 is as follows: Connect the two sides of the switch corresponding to the first test point and the third grounding point, connect the two sides of the switch corresponding to the second test point and the fourth grounding point, disconnect the second, third, and fourth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the eighth input shaft; connect the two sides of the switch corresponding to the first test point and the fifth grounding point, connect the two sides of the switch corresponding to the second test point and the sixth grounding point, disconnect the second, fifth, and sixth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the eighth intermediate shaft; connect the two sides of the switch corresponding to the first test point and the seventh grounding point, connect the two sides of the switch corresponding to the eighth grounding point, disconnect the second, seventh, and eighth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the eighth differential shaft;

[0034] If the voltage at the front end of the eighth input shaft, the voltage at the rear end of the eighth input shaft, the voltage at the front end of the eighth intermediate shaft, the voltage at the rear end of the eighth intermediate shaft, the voltage at the front end of the eighth differential shaft, and the voltage at the rear end of the eighth differential shaft are all less than the allowable value of the shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the front end of the motor; otherwise, the test of mode nine will be performed.

[0035] The test method for Mode Nine is as follows: Connect the two sides of the switch corresponding to the first test point and the third grounding point, connect the two sides of the switch corresponding to the second test point and the fourth grounding point, disconnect the first, third, and fourth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the ninth input shaft; connect the two sides of the switch corresponding to the first test point and the fifth grounding point, connect the two sides of the switch corresponding to the second test point and the sixth grounding point, disconnect the first, fifth, and sixth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the ninth intermediate shaft; connect the two sides of the switch corresponding to the first test point and the seventh grounding point, connect the two sides of the switch corresponding to the second test point and the eighth grounding point, disconnect the first, seventh, and eighth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the ninth differential shaft;

[0036] If the voltage at the front end of the ninth input shaft, the voltage at the rear end of the ninth input shaft, the voltage at the front end of the ninth intermediate shaft, the voltage at the rear end of the ninth intermediate shaft, the voltage at the front end of the ninth differential shaft, and the voltage at the rear end of the ninth differential shaft are all less than the allowable value of the shaft voltage, the electric drive assembly adopts the countermeasure of adding a grounding ring at the rear end of the motor; otherwise, the test of mode ten is performed.

[0037] The test method for Mode 10 is as follows: Connect the first test point to both sides of the switch corresponding to the third grounding point, connect the second test point to both sides of the switch corresponding to the fourth grounding point, disconnect the third and fourth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the tenth input shaft; connect the first test point to both sides of the switch corresponding to the fifth grounding point, connect the second test point to both sides of the switch corresponding to the sixth grounding point, disconnect the fifth and sixth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the tenth intermediate shaft; connect the first test point to both sides of the switch corresponding to the seventh grounding point, connect the second test point to both sides of the switch corresponding to the eighth grounding point, disconnect the seventh and eighth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the tenth differential shaft;

[0038] If the voltage at the front end of the tenth input shaft, the voltage at the rear end of the tenth input shaft, the voltage at the front end of the tenth intermediate shaft, the voltage at the rear end of the tenth intermediate shaft, the voltage at the front end of the tenth differential shaft, and the voltage at the rear end of the tenth differential shaft are all less than the allowable shaft voltage, then the electric drive assembly adopts the countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, the countermeasure is to add an insulating coating at the bearing in the gearbox that is not less than the allowable shaft voltage.

[0039] According to the shaft voltage test method of electric drive assembly provided in this application, when it is determined that the bearings of the current electric drive assembly have the risk of electrical corrosion on the motor side and the risk of electrical corrosion on the gearbox side, the test is carried out according to mode seven and mode one. If the shaft voltage of all bearing positions in the electric drive assembly measured by mode seven and mode one is less than the allowable value of shaft voltage, then no countermeasures need to be taken; otherwise, the test is carried out according to mode eight and mode four.

[0040] If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 8 and Mode 4 are less than the allowable shaft voltage, then the solution of installing a grounding ring at the front end of the motor should be adopted to reduce the shaft voltage; otherwise, the test should be performed according to Mode 9 and Mode 5.

[0041] If the shaft voltages of all bearing positions in the electric drive assembly measured in Modes 9 and 5 are less than the allowable shaft voltage, then a solution of installing a grounding ring at the rear end of the motor should be adopted to reduce the shaft voltage; otherwise, tests should be conducted according to Modes 10 and 6.

[0042] If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 10 and Mode 6 are less than the allowable shaft voltage, then a solution of installing grounding rings at both the front and rear ends of the motor is adopted to reduce the shaft voltage.

[0043] If the bearing shaft voltage is consistently not less than the allowable shaft voltage value in all four modes, the solution is to replace the motor bearing with a ceramic ball bearing or to use an insulating coating to insulate the bearing from the housing and shaft it contacts. Alternatively, the solution is to replace the gearbox bearing with a ceramic ball bearing.

[0044] This application also provides an electric drive assembly shaft voltage testing system, which operates according to any of the above-described electric drive assembly shaft voltage testing methods, including:

[0045] The grounding module includes a first grounding point and a second grounding point located at both ends of the motor shaft, a third grounding point and a fourth grounding point located at the bearings at both ends of the input shaft assembly, a fifth grounding point and a sixth grounding point located at the bearings at both ends of the intermediate shaft assembly, a seventh grounding point and an eighth grounding point located at the bearings at both ends of the differential assembly, a ninth grounding point and a tenth grounding point located at the bearings at both ends of the motor shaft, and an eleventh grounding point located on the main housing of the electric drive assembly.

[0046] The measuring point module includes a first measuring point and a second measuring point located at both ends of the motor shaft.

[0047] The test module controls the on / off state of eleven grounding points to achieve different test modes and records the voltage of the first and second test points under each test mode.

[0048] The judgment module analyzes and determines whether corresponding countermeasures need to be formulated for the electric drive assembly based on the voltage of the first and second test points under each test mode.

[0049] According to the electric drive assembly shaft voltage testing system provided in this application, the testing module includes...

[0050] The first module implements the Mode 1 test method by disconnecting the first grounding point and the second grounding point and connecting the remaining grounding points, and records the voltages of the first test point and the second test point under the Mode 1 test method as the front-end voltage and the rear-end voltage of the first motor.

[0051] The second module implements the Mode 2 test method by connecting the ninth, tenth, and eleventh grounding points and disconnecting the remaining grounding points, and records the voltages of the first and second test points under the Mode 2 test method as the front-end voltage of the second motor and the rear-end voltage of the second motor.

[0052] The third module implements the mode three test method by disconnecting the first grounding point, the second grounding point, the ninth grounding point, and the tenth grounding point and connecting the remaining grounding points, and records the voltages of the first and second test points under the mode three test method as the front-end voltage and the rear-end voltage of the third motor.

[0053] The fourth module implements the Mode 4 test method by connecting the first grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point and disconnecting the remaining grounding points, and records the voltages of the first and second test points under the Mode 4 test method as the front-end voltage and the rear-end voltage of the fourth motor.

[0054] The fifth module implements the mode five test method by connecting the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point and disconnecting the remaining grounding points, and records the voltages of the first and second test points under the mode five test method as the front-end voltage and the rear-end voltage of the fifth motor.

[0055] The sixth module implements the Mode 6 test method by connecting the first grounding point, the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point and disconnecting the remaining grounding points, and records the voltages of the first and second test points under the Mode 6 test method as the front-end voltage and the rear-end voltage of the sixth motor.

[0056] The seventh module connects the first test point to the switch corresponding to the third grounding point, connects the second test point to the switch corresponding to the fourth grounding point, disconnects the first, second, third, and fourth grounding points, and connects the remaining grounding points to implement the mode seven test method. It records the voltages at the first and second test points under the mode seven test method as the front and rear voltages of the seventh input shaft. It then connects the first test point to the switch corresponding to the fifth grounding point, connects the second test point to the switch corresponding to the sixth grounding point, and disconnects the first and second grounding points. Connect the fifth and sixth grounding points, and the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltages at the first and second measuring points as the voltage at the front and rear ends of the seventh intermediate shaft. Connect the first measuring point to the switch corresponding to the seventh grounding point on both sides, and connect the second measuring point to the switch corresponding to the eighth grounding point on both sides. Disconnect the first, second, seventh, and eighth grounding points, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltages at the first and second measuring points as the voltage at the front and rear ends of the seventh differential shaft.

[0057] The eighth module implements the Mode 8 test method by connecting the first test point to the two sides of the switch corresponding to the third grounding point, connecting the second test point to the two sides of the switch corresponding to the fourth grounding point, disconnecting the second, third, and fourth grounding points, and connecting the remaining grounding points. It records the voltages of the first and second test points under the Mode 8 test method as the front and rear voltages of the eighth input shaft. The module further connects the first test point to the two sides of the switch corresponding to the fifth grounding point, connects the second test point to the two sides of the switch corresponding to the sixth grounding point, disconnects the second, fifth, and sixth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the front and rear voltages of the eighth intermediate shaft. Finally, it connects the first test point to the two sides of the switch corresponding to the seventh grounding point, connects the second test point to the two sides of the switch corresponding to the eighth grounding point, disconnects the second, seventh, and eighth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the front and rear voltages of the eighth differential shaft.

[0058] The ninth module implements the Mode 9 test method by connecting the first test point to the switch corresponding to the third grounding point, connecting the second test point to the switch corresponding to the fourth grounding point, disconnecting the first, third, and fourth grounding points, and connecting the remaining grounding points. It records the voltages of the first and second test points as the front and rear voltages of the ninth input shaft under the Mode 9 test method. The module further connects the first test point to the switch corresponding to the fifth grounding point, connects the second test point to the switch corresponding to the sixth grounding point, disconnects the first, fifth, and sixth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the front and rear voltages of the ninth intermediate shaft. Finally, it connects the first test point to the switch corresponding to the seventh grounding point, connects the second test point to the switch corresponding to the eighth grounding point, disconnects the first, seventh, and eighth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the front and rear voltages of the ninth differential shaft.

[0059] The tenth module implements the Mode 10 test method by connecting the first test point to the two sides of the switch corresponding to the third grounding point, connecting the second test point to the two sides of the switch corresponding to the fourth grounding point, disconnecting the third and fourth grounding points, and connecting the remaining grounding points. The module records the voltages of the first and second test points under Mode 10 as the voltage at the front and rear ends of the tenth input shaft. It then connects the first test point to the two sides of the switch corresponding to the fifth grounding point, connects the second test point to the two sides of the switch corresponding to the sixth grounding point, disconnects the fifth and sixth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the voltage at the front and rear ends of the tenth intermediate shaft. Finally, it connects the first test point to the two sides of the switch corresponding to the seventh grounding point, connects the second test point to the two sides of the switch corresponding to the eighth grounding point, disconnects the seventh and eighth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the voltage at the front and rear ends of the tenth differential shaft.

[0060] According to the electric drive assembly shaft voltage testing system provided in this application, the judgment module includes,

[0061] The corrosion risk assessment module determines that the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, the second motor rear end voltage, the third motor front end voltage, and the third motor rear end voltage are all common-mode waveforms, and therefore makes the judgment that the risk of electro-corrosion of the bearings in the current electric drive assembly is low and no countermeasures need to be formulated.

[0062] The motor-side corrosion risk assessment module determines that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side when the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, and the second motor rear end voltage are all breakdown waveforms, and the waveforms of the third motor front end voltage and the third motor rear end voltage are common mode waveforms. It then makes a judgment that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side and needs to be further judged in combination with the voltage and corresponding countermeasures should be made.

[0063] The gearbox-side corrosion risk assessment module determines that when the waveforms of the voltage at the front end of the second motor and the voltage at the rear end of the second motor are common-mode waveforms, and the waveforms of the voltage at the front end of the first motor, the voltage at the rear end of the first motor, the voltage at the front end of the third motor, and the voltage at the rear end of the third motor are breakdown waveforms, it determines that the bearing of the current electric drive assembly has a risk of gearbox-side electrical corrosion, and further judgment needs to be made in conjunction with the voltage and corresponding countermeasures should be taken.

[0064] The dual-side corrosion risk assessment module determines that when the waveforms of the voltage at the front end of the first motor, the rear end of the first motor, the front end of the second motor, the rear end of the second motor, the front end of the third motor, and the rear end of the third motor are all breakdown waveforms, the module determines that the bearings of the current electric drive assembly have a risk of electrical corrosion on both the gearbox side and the motor side, and that further assessment based on the voltage is needed to determine appropriate countermeasures.

[0065] According to the electric drive assembly shaft voltage testing system provided in this application, the judgment module further includes,

[0066] No countermeasure formulation module, which is used to determine that the current bearing has low electrical corrosion risk and / or gearbox side electrical corrosion risk when it is determined that the bearing of the current electric drive assembly has low electrical corrosion risk and no countermeasure needs to be formulated.

[0067] The fourth countermeasure formulation module is used to further determine the risk of motor-side electrical corrosion of the bearings of the current electric drive assembly and to formulate a countermeasure of adding a grounding ring at the front end of the motor when it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the motor side and the front end voltages of the first motor, the second motor, the second motor, the third motor, and the third motor are all less than the allowable value of the shaft voltage.

[0068] The fifth countermeasure formulation module is used to make further judgments based on the fifth motor front-end voltage and fifth motor rear-end voltage collected by the mode five test method when the condition that the fourth motor front-end voltage and the fourth motor rear-end voltage are both less than the allowable value of the shaft voltage is not met. When the fifth motor front-end voltage and the fifth motor rear-end voltage are both less than the allowable value of the shaft voltage, the module formulates a countermeasure to add a grounding ring at the motor rear end.

[0069] The sixth countermeasure formulation module is used to further determine the sixth motor front-end voltage and sixth motor rear-end voltage based on the test method of mode six when the condition that the fifth motor front-end voltage and the fifth motor rear-end voltage are both less than the allowable shaft voltage is not met. If the sixth motor front-end voltage and the sixth motor rear-end voltage are both less than the allowable shaft voltage, the module formulates a countermeasure to add grounding rings at both ends of the motor. Otherwise, the module formulates a countermeasure to replace all bearings of the electric drive assembly with ceramic ball bearings or to use an insulating coating to insulate the bearings from the housing and shaft they contact.

[0070] According to the electric drive assembly shaft voltage testing system provided in this application, the judgment module further includes,

[0071] The seventh countermeasure formulation module is used to further determine, based on the seventh input shaft front voltage, seventh input shaft rear voltage, seventh intermediate shaft front voltage, seventh intermediate shaft rear voltage, seventh differential shaft front voltage, and seventh differential shaft rear voltage collected by the mode seven test method, when it is determined that there is a risk of gearbox-side electrical corrosion in the bearing of the current electric drive assembly and the first motor front voltage, first motor rear voltage, second motor front voltage, second motor rear voltage, third motor front voltage, and third motor rear voltage are all less than the allowable shaft voltage value. When the seventh input shaft front voltage, seventh input shaft rear voltage, seventh intermediate shaft front voltage, seventh intermediate shaft rear voltage, seventh differential shaft front voltage, and seventh differential shaft rear voltage are all less than the allowable shaft voltage value, it makes a judgment that no countermeasures need to be formulated for the gearbox bearing of the electric drive assembly.

[0072] The eighth countermeasure formulation module is used to further determine the voltages of the eighth input shaft front end, eighth input shaft rear end, seventh intermediate shaft front end, seventh intermediate shaft rear end, seventh differential shaft front end, and seventh differential shaft rear end when the conditions are not met (all of these voltages are less than the allowable shaft voltage value). Based on the voltages of the eighth input shaft front end, eighth input shaft rear end, eighth intermediate shaft front end, eighth intermediate shaft rear end, eighth differential shaft front end, and eighth differential shaft rear end collected by the mode eight test method, the module formulates a countermeasure to add a grounding ring at the front end of the motor when all of these voltages are less than the allowable shaft voltage value.

[0073] The ninth countermeasure formulation module is used to further determine the voltages of the ninth input shaft front end, eighth input shaft rear end, eighth intermediate shaft front end, eighth intermediate shaft rear end, eighth differential shaft front end, and eighth differential shaft rear end when the conditions are not met (all of these voltages are less than the allowable shaft voltage value). Based on the voltages of the ninth input shaft front end, ninth input shaft rear end, ninth intermediate shaft front end, ninth intermediate shaft rear end, ninth differential shaft front end, and ninth differential shaft rear end, the module further determines the countermeasure of adding a grounding ring at the rear end of the motor when all of these voltages are less than the allowable shaft voltage value.

[0074] The tenth countermeasure formulation module is used to further determine the following conditions when the voltages of the ninth input shaft front end, the ninth input shaft rear end, the ninth intermediate shaft front end, the ninth intermediate shaft rear end, the ninth differential shaft front end, and the ninth differential shaft rear end are all less than the allowable shaft voltage value: based on the voltages of the tenth input shaft front end, the tenth input shaft rear end, the tenth intermediate shaft front end, the tenth intermediate shaft rear end, the tenth differential shaft front end, and the tenth differential shaft rear end, collected by the mode ten test method. If all of these voltages are less than the allowable shaft voltage value, the module formulates a countermeasure to add grounding rings at both ends of the motor; otherwise, it formulates a countermeasure to add an insulating coating at the bearings in the electric drive assembly that are not less than the allowable shaft voltage value.

[0075] According to the electric drive assembly shaft voltage testing system provided in this application, the judgment module further includes,

[0076] The eleventh countermeasure formulation module is used to test according to mode seven and mode one when the bearings of the current electric drive assembly have the risk of electrical corrosion on the motor side and the risk of electrical corrosion on the gearbox side. If the shaft voltage of all bearing positions in the electric drive assembly measured by mode seven and mode one is less than the allowable value of shaft voltage, then no countermeasures need to be taken; otherwise, the test is carried out according to mode eight and mode four.

[0077] If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 8 and Mode 4 are less than the allowable shaft voltage, then the solution of installing a grounding ring at the front end of the motor should be adopted to reduce the shaft voltage; otherwise, the test should be performed according to Mode 9 and Mode 5.

[0078] If the shaft voltages of all bearing positions in the electric drive assembly measured in Modes 9 and 5 are less than the allowable shaft voltage, then a solution of installing a grounding ring at the rear end of the motor should be adopted to reduce the shaft voltage; otherwise, tests should be conducted according to Modes 10 and 6.

[0079] If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 10 and Mode 6 are less than the allowable shaft voltage, then a solution of installing grounding rings at both the front and rear ends of the motor is adopted to reduce the shaft voltage.

[0080] If the bearing shaft voltage is consistently not less than the allowable shaft voltage value in all four modes, then a countermeasure is formulated to replace the motor bearing with a ceramic ball bearing or to use an insulating coating to insulate the bearing from the housing and shaft it contacts. A countermeasure is also formulated to replace the gearbox bearing with a ceramic ball bearing.

[0081] The advantages of this application are as follows: 1. By setting multiple grounding points and multiple measuring points on the electric drive assembly, this application can control the on / off state of the grounding points to achieve the measurement of shaft voltage in different modes. It can obtain shaft voltage in various modes without disassembling the electric drive assembly. It can not only evaluate common mode voltage but also breakdown voltage. The test items are rich, the test efficiency is extremely high, and the test time is short. It can also formulate different countermeasures for different electrical corrosion risks. The formulated countermeasures are also practical and feasible, requiring minimal modifications and cost, and have great promotional value.

[0082] 2. The main housing of the electric drive assembly of this application is equipped with an insulating base, and the shaft voltage release path is changed from the traditional shaft-bearing-housing-ground wire to shaft-bearing-lead wire-switch-ground wire through the lead wire and switch. By switching the switch on and off, the shaft voltage release path can be made controllable in real time. The grounding point control operation is very simple. Moreover, when the grounding point is grounded, it can indicate the status of adding a grounding ring to solve the problem. It is easy to formulate a solution to whether a grounding ring can be added to solve the risk of electro-corrosion. The operation is extremely simple and convenient.

[0083] 3. This application uses three modes to represent three different electric drive assembly states, which correspond to the actual vehicle state of the electric drive assembly. The electric drive assembly is in a state where the gearbox side is insulated and the motor bearing is connected to the housing. The electric drive assembly is in a state where the motor side is insulated and the gearbox bearing is connected to the housing. By testing the three modes, the specific situation of the current electric drive assembly's risk of electro-corrosion can be accurately determined, which is convenient for formulating corresponding countermeasures in the future.

[0084] 4. The method for determining whether there is a risk of electro-corrosion in this application is very simple. The waveforms of the front-end voltage of the first motor, the rear-end voltage of the first motor, the front-end voltage of the second motor, the rear-end voltage of the second motor, the front-end voltage of the third motor, and the rear-end voltage of the third motor are analyzed by an oscilloscope. Not only can the common-mode waveform be analyzed, but also the breakdown waveform can be analyzed. The analysis content is richer and the analysis results are more accurate, which can more accurately determine the location of the current electro-corrosion risk in the electric drive assembly.

[0085] 5. In cases where an initial assessment indicates a risk of electro-corrosion, this application further assesses the voltage at the front end of the first motor, the rear end of the first motor, the front end of the second motor, the rear end of the second motor, the front end of the third motor, and the rear end of the third motor to avoid misjudgment. This further assessment determines whether countermeasures are necessary, improves the accuracy of the assessment, and facilitates the formulation of appropriate countermeasures.

[0086] 6. This application further assesses the risk of electro-corrosion in the motor-side bearing by using test methods of Mode 4, Mode 5 and Mode 6 to conduct the assessment and analysis. This allows for the accurate acquisition of countermeasures when the motor-side bearing is at risk of electro-corrosion. Corresponding measures can be developed for different situations, and these measures can precisely address the risk of electro-corrosion in the motor side.

[0087] 7. This application further assesses the risk of electro-corrosion in the gearbox side bearing. By using test methods of Mode 7, Mode 8, Mode 9 and Mode 10, the assessment and analysis can accurately obtain countermeasures when there is a risk of electro-corrosion in the gearbox side bearing. Corresponding measures can be formulated for different situations, and the formulated measures can accurately solve the risk of electro-corrosion in the gearbox side.

[0088] 8. When the bearings of the current electric drive assembly have the risk of electrical corrosion on the motor side and the gearbox side, this application collects the shaft voltage of all bearings through test methods of Mode 1, Mode 4, Mode 5, Mode 6, Mode 7, Mode 8, Mode 9 and Mode 10. By analyzing the shaft voltage of each bearing separately, it can determine whether there is a problem with the bearing. If there is a problem, corresponding countermeasures can be formulated. This is more targeted and can quickly find the location of the bearing with the risk of electrical corrosion and quickly formulate corresponding countermeasures.

[0089] 9. This application also provides an electric drive assembly shaft voltage testing system. The testing system of this application can be integrated into the control system to form an automatic testing and countermeasure output system, which facilitates electric drive assembly testing and further improves testing efficiency.

[0090] The electric drive assembly shaft voltage test method of this application is simple, can accurately determine whether there is a risk of electro-corrosion in the electric drive assembly bearing, has extremely limited test items, and can formulate corresponding countermeasures based on the corresponding risks. The corresponding countermeasures require minimal modifications and are extremely low in cost, making it of great promotional value. Attached Figure Description

[0091] Figure 1 This application includes a schematic diagram of the grounding point and measuring point arrangement for the electric drive assembly.

[0092] Figure 2 : A schematic diagram of the shaft voltage test structure for the electric drive assembly in this application;

[0093] Wherein: 1—First grounding point; 2—Second grounding point; 3—Third grounding point; 4—Fourth grounding point; 5—Fifth grounding point; 6—Sixth grounding point; 7—Seventh grounding point; 8—Eighth grounding point; 9—Ninth grounding point; 10—Tenth grounding point; 11—Eleventh grounding point; 12—Oscilloscope grounding wire; 13—First measuring point; 14—Second measuring point; 15—Main housing; 16—Motor stator; 17—Motor rotor; 18—Second shaft voltage measurement point; 19—Second shaft voltage grounding point; 20—N bearing; 21—M bearing; 22—First shaft voltage measurement point; 23—First shaft voltage grounding point; 24—A bearing; 25—B bearing; 26—Input shaft; 27—D bearing; 28—C bearing; 29—Intermediate shaft; 30—F bearing; 31—Differential gear; 32—E bearing; 33—Insulating base. Detailed Implementation

[0094] The embodiments of this application are described in detail below, 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 this application, and should not be construed as limiting this application.

[0095] In the description of this application, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0096] 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 application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0097] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0098] This application relates to a method for testing the shaft voltage of an electric drive assembly. By setting ground points and testing points on the electric drive assembly, and controlling the on / off state of the grounding point, different states of the electric drive assembly can be achieved. When the grounding point is grounded, the state of installing a grounding ring at that location can be simulated, facilitating the development of corresponding countermeasures to address the risk of electro-corrosion. The entire testing method is simple and easy to operate. Furthermore, this application can analyze not only common-mode waveforms but also breakdown waveforms, providing richer analysis content and more accurate results, enabling a more precise determination of the location of electro-corrosion risk in the electric drive assembly.

[0099] Specifically, such as Figures 1-2 As shown, a method for testing shaft voltage of an electric drive assembly according to this application includes the following steps:

[0100] S1. Grounding points are arranged on the electric drive assembly, including a first grounding point 1 and a second grounding point 2 located at both ends of the motor shaft, a third grounding point 3 and a fourth grounding point 4 located at the bearings at both ends of the input shaft 26 assembly, a fifth grounding point 5 and a sixth grounding point 6 located at the bearings at both ends of the intermediate shaft 29 assembly, a seventh grounding point 7 and an eighth grounding point located at the bearings at both ends of the differential 31 assembly, a ninth grounding point 9 and a tenth grounding point 10 located at the bearings at both ends of the motor shaft, and an eleventh grounding point 11 located on the main housing 15 of the electric drive assembly;

[0101] The purpose of arranging grounding points on the electric drive assembly is to bring out the bearing locations on the electric drive assembly, making it convenient to ground the bearing locations later, simulating the effect of installing a grounding ring at that location; the electric drive assembly of this application includes a main housing 15, a motor shaft, a motor stator 16, a motor rotor 17, an input shaft 26, an intermediate shaft 29, and a differential 31. The bearings involved on the electric drive assembly are: bearings at both ends of the motor shaft, namely bearing M 21 and bearing N 20 at the front end of the motor shaft; bearings at both ends of the input shaft 26, namely bearing B 25 at the front end of the input shaft 26 and bearing A 24 at the rear end of the input shaft 26; bearings at both ends of the intermediate shaft 29, namely bearing D at the front end of the intermediate shaft 29 and bearing C at the rear end of the intermediate shaft 29; bearings at both ends of the differential 31 axially, namely... The F bearing 30 at the front end of the differential 31 and the E bearing 32 at the rear end of the differential 31 have grounding points arranged on the A bearing 24, B bearing 25, C bearing, D bearing, E bearing 32, F bearing 30, M bearing 21, and N bearing 20 respectively; M bearing 21 corresponds to the ninth grounding point 9, N bearing 20 corresponds to the tenth grounding point 10, A bearing 24 corresponds to the third grounding point 3, B bearing 25 corresponds to the fourth grounding point 4, D bearing corresponds to the fifth grounding point 5, C bearing corresponds to the sixth grounding point 6, F bearing 30 corresponds to the seventh grounding point 7, and E bearing 32 corresponds to the eighth grounding point 8; in addition, there are grounding points at both ends of the motor shaft, namely the ninth grounding point 9 and the tenth grounding point 10 at the front end of the motor shaft, plus the eleventh grounding point 11 on the main housing 15 of the electric drive assembly;

[0102] The grounding points are arranged by placing a lead wire at each grounding point, with one end of the lead wire passing through the main housing 15 and entering the insulating base 33 at the grounding point (e.g., Figure 2 The insulating base 33 shown in the schematic diagram is connected to the corresponding grounding point, and the other end is connected to the grounding wire. A switch is arranged on the lead wire. The purpose of controlling the on / off state of the grounding point can be achieved by opening and closing the switch. When the grounding point is connected, it means that the switch is closed and the electric drive assembly corresponding to the grounding point is grounded. When the grounding point is disconnected, it means that the switch is open and the electric drive assembly corresponding to the grounding point is not grounded.

[0103] S2. Arrange the first measuring point 13 and the second measuring point 14 at both ends of the motor shaft;

[0104] Measuring the shaft voltage of the electric drive assembly is essentially measuring the voltage across the two ends of the motor shaft. Therefore, it is necessary to arrange measuring points at both ends of the motor shaft, namely, the first measuring point 13 at the first grounding point 1 (e.g., ...). Figure 2 As shown, the first measuring point 13 includes the first axis voltage measuring point 22 and the first axis voltage grounding point 23) and the second measuring point 14 at the second grounding point 2 (as shown). Figure 2 As shown, the second measuring point 14 includes the second axis voltage measuring point 18 and the second axis voltage grounding point 19.

[0105] All grounding points and measurement points are connected to the oscilloscope (e.g., Figure 1 The oscilloscope ground wire 12 shown is connected to the oscilloscope. The data collected by the measurement point is transmitted to the oscilloscope, and the waveform of the voltage collected on the oscilloscope is used for judgment and analysis.

[0106] S3. Control the on / off state of eleven grounding points to achieve different test modes. Use a bench to drive the electric drive assembly to run. Record the voltages of the first measuring point 13 and the second measuring point 14 under each test mode as the front shaft voltage and the rear shaft voltage of the motor, respectively.

[0107] By controlling the switches on eleven grounding points, the on / off state of the grounding points can be controlled. The on / off state of the grounding points at different locations corresponds to different working modes of the electric drive assembly. By controlling the on / off state of the switches, testing in different modes can be achieved.

[0108] The electric drive assembly of this application was installed on a test bench for simulation experiments;

[0109] S4. Analyze the recorded front and rear shaft voltages of the motor to determine whether corresponding countermeasures need to be formulated for the electric drive assembly.

[0110] In some embodiments of this application, step S3 described above has been optimized. Specifically, the method for controlling the on / off state of the eleven grounding points to achieve different test modes in this embodiment is as follows: The preliminary test of the shaft voltage of the electric drive assembly is divided into three modes, namely...

[0111] Mode 1: Disconnect the first grounding point 1 and the second grounding point 2, connect the remaining grounding points, and use a test bench to drive the electric drive assembly. Record the voltage at the first measuring point 13 and the second measuring point 14 as the voltage U at the front end of the first motor. f1 and the voltage U at the rear end of the first motor r1 ;

[0112] Mode 2: Connect the ninth grounding point 9, the tenth grounding point 10, and the eleventh grounding point 11, disconnect the remaining grounding points, and use a test bench to drive the electric drive assembly. Record the voltage at the first measuring point 13 and the second measuring point 14 as the voltage U at the front end of the second motor. f2 Second motor back-end voltage U r2 ;

[0113] Mode 3: Disconnect the first grounding point 1, the second grounding point 2, the ninth grounding point 9, and the tenth grounding point 10, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltage at the first measuring point 13 and the second measuring point 14 as the voltage U at the front end of the third motor. f3 and the voltage U at the rear end of the third motor r3 .

[0114] The three modes tested in the preliminary test correspond to three different states of the electric drive assembly. The state corresponding to mode one is consistent with the electric drive assembly running in the actual vehicle. The state corresponding to mode two is that the gearbox side is insulated, and the bearing on the motor side is connected to the main housing 15. The state corresponding to mode three is that the motor side is insulated, and the bearing on the gearbox side is connected to the main housing 15.

[0115] By collecting the motor front-end voltage and motor rear-end voltage under three different modes, it is possible to preliminarily analyze whether there is a risk of electro-corrosion and, if so, the possible location of the risk.

[0116] In a further embodiment of this application, step S4 above has been optimized. Specifically, the method for analyzing the recorded front-end shaft voltage and rear-end shaft voltage of the motor is as follows: if the first front-end voltage U f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 The voltage U at the rear end of the second motor r2 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 Since all the waveforms are common-mode waveforms, it can be determined that the risk of electro-corrosion of the bearings in the current electric drive assembly is low, and no countermeasures need to be formulated.

[0117] If the voltage at the front end of the first motor is U f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 Second motor back-end voltage U r2 All waveforms are breakdown waveforms, and the voltage U at the front end of the third motor is... f3 and the voltage U at the rear end of the third motor r3 The waveform is a common-mode waveform, indicating that the bearing of the current electric drive assembly is at risk of electrical corrosion on the motor side. Further judgment and corresponding countermeasures are needed based on the voltage.

[0118] If the voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 The waveform is a common-mode waveform, and the voltage U at the front end of the first motor is... f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 The waveform is a breakdown waveform, indicating that the bearing of the current electric drive assembly is at risk of electro-corrosion on the gearbox side. Further judgment and corresponding countermeasures are needed based on the voltage.

[0119] If the voltage at the front end of the first motor is U f1 The voltage U at the rear end of the first motor r1The voltage U at the front end of the second motor f2 The voltage U at the rear end of the second motor r2 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 The waveforms are all breakdown waveforms, indicating that the bearings of the current electric drive assembly are at risk of electrical corrosion on both the gearbox and motor sides. Further judgment and corresponding countermeasures are needed based on the voltage.

[0120] By analyzing the waveforms of the motor front-end voltage and motor rear-end voltage collected during the initial test, it is possible to roughly determine whether there is a risk of electro-corrosion in the current electric drive assembly. If there is a risk of electro-corrosion, it can be determined whether the risk occurs on the motor side, the gearbox side, or both sides.

[0121] In a further embodiment of this application, the above-described analysis method is further optimized. When the initial test obtains the voltage U at the front end of the first motor... f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 The voltage U at the rear end of the second motor r2 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 The next step is to determine the waveform of the aforementioned voltage values. After the waveform determination is completed, the numerical values ​​are then determined. That is, when it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the motor side and / or on the gearbox side, if the voltage U at the front end of the first motor... f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 The voltage U at the rear end of the second motor r2 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 If all values ​​are less than the allowable shaft voltage, the risk of bearing electro-corrosion is low and no countermeasures are needed. Otherwise, further judgment based on the voltage is required and appropriate countermeasures should be taken.

[0122] The voltage U at the front end of the first motor f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 The voltage U at the rear end of the second motor r2 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 All values ​​are less than the allowable shaft voltage, indicating that the voltage values ​​collected by the preliminary testing method are relatively small and insufficient to break down the oil film and cause the risk of electro-corrosion. Under these circumstances, there is no need to develop countermeasures to eliminate the risk of electro-corrosion.

[0123] In a preferred embodiment of this application, the above-described analysis method is further optimized. Specifically, when determining that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side, if the voltage U at the front end of the first motor... f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 The voltage U at the rear end of the second motor r2 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 If the voltage is not less than the allowable value of the shaft voltage (the value set according to the specifications of the electric drive assembly), it proves that the voltage U at the front end of the first motor is... f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 The voltage U at the rear end of the second motor r2 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 If at least one of the voltages exceeds the allowable value of the shaft voltage, further testing is required.

[0124] First, test mode four is performed. The test method for mode four is as follows: connect the first grounding point 1, the ninth grounding point 9, the tenth grounding point 10, and the eleventh grounding point 11, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltage at the first measuring point 13 and the second measuring point 14 as the front-end voltage U of the fourth motor. f4 and the voltage U at the back end of the fourth motor r4 The electric drive assembly corresponding to Mode 4 is in a state where the gearbox side is insulated and the motor side bearing is connected to the main housing 15.

[0125] Further analysis of the test results for Mode 4 is needed. If the front-end voltage U of the fourth motor... f4 and the voltage U at the back end of the fourth motor r4 If all values ​​are less than the allowable shaft voltage, the electric drive assembly will use a grounding ring added to the front end of the motor; otherwise, test mode five will be performed.

[0126] The test method for Mode 5 is as follows: Connect the second grounding point 2, the ninth grounding point 9, the tenth grounding point 10, and the eleventh grounding point 11, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltage at the first measuring point 13 and the second measuring point 14 as the voltage U at the front end of the fifth motor. f5 and the voltage U at the rear end of the fifth motor r5 The electric drive assembly corresponding to mode five is in a state where the gearbox side is insulated and the motor side bearing is connected to the main housing 15.

[0127] Further analysis of the test results for Mode 5 is needed. If the voltage U at the front end of the fifth motor...f5 and the voltage U at the rear end of the fifth motor r5 If all values ​​are less than the allowable shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the rear end of the motor; otherwise, test mode six will be performed.

[0128] The test method for Mode 6 is as follows: Connect the first grounding point 1, the second grounding point 2, the ninth grounding point 9, the tenth grounding point 10, and the eleventh grounding point 11, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltage at the first measuring point 13 and the second measuring point 14 as the voltage U at the front end of the sixth motor. f6 and the voltage U at the rear end of the sixth motor r6 The electric drive assembly corresponding to mode six is ​​in a state where the gearbox side is insulated and the motor side bearing is connected to the main housing 15.

[0129] If the voltage at the front end of the sixth motor is U f6 and the voltage U at the rear end of the sixth motor r6 If all values ​​are less than the allowable shaft voltage, the electric drive assembly adopts the countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, the countermeasure is to replace all bearings of the electric drive assembly with ceramic ball bearings or use an insulating coating to insulate the bearings from the main housing 15 and the shaft that are in contact with them.

[0130] In a further embodiment of this application, the above-described analysis method is further optimized. Specifically, when it is determined that the bearing of the current electric drive assembly has a risk of electro-corrosion on the gearbox side, if the voltage U at the front end of the first motor... f1 The voltage U at the rear end of the first motor r1 The voltage U at the front end of the second motor f2 The voltage U at the rear end of the second motor r2 The voltage U at the front end of the third motor f3 and the voltage U at the rear end of the third motor r3 If the condition that all values ​​are less than the allowable value of the shaft voltage is not met, test mode seven shall be performed;

[0131] The test method for Mode 7 is as follows: Connect the first test point 13 to the two sides of the switch corresponding to the third grounding point 3, connect the second test point 14 to the two sides of the switch corresponding to the fourth grounding point, disconnect the first grounding point 1, the second grounding point 2, the third grounding point 3, and the fourth grounding point 4, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltage of the first test point 13 and the second test point 14 as the voltage U at the front end of the seventh input shaft. a7 and the voltage U at the rear end of the seventh input shaft b7Connect the first measuring point 13 to the two sides of the switch corresponding to the fifth grounding point 5, and connect the second measuring point 14 to the two sides of the switch corresponding to the sixth grounding point 6. Disconnect the first grounding point 1, the second grounding point 2, the fifth grounding point 5, and the sixth grounding point 6, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly to run, and record the voltage at the first measuring point 13 and the second measuring point 14 as the voltage U at the rear end of the seventh intermediate shaft. d7 and the voltage U at the rear end of the seventh intermediate shaft c7 Connect the first measuring point 13 to the two sides of the switch corresponding to the seventh grounding point 7, and connect the second measuring point 14 to the two sides of the switch corresponding to the eighth grounding point 8. Disconnect the first grounding point 1, the second grounding point 2, the seventh grounding point 7, and the eighth grounding point 8, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltage at the first and second measuring points as the voltage U at the front end of the seventh differential shaft. f7 and the voltage U at the rear end of the seventh differential shaft e7 ;

[0132] If the voltage at the front end of the seventh input shaft U a7 The voltage U at the rear end of the seventh input shaft b7、 Seventh intermediate shaft rear end voltage U d7、 Seventh intermediate shaft rear end voltage U c7、 Voltage U at the front end of the seventh differential shaft f7、 Voltage U at the rear end of the seventh differential shaft e7 If all values ​​are less than the allowable shaft voltage, it is determined that the risk of electrical corrosion of the bearings at both ends of the input shaft 26 component of the current electric drive assembly is low, and no countermeasures are required; otherwise, test mode eight is performed.

[0133] The test method for Mode 8 is as follows: Connect the first test point 13 to the two sides of the switch corresponding to the third grounding point 3, connect the second test point 14 to the two sides of the switch corresponding to the fourth grounding point, disconnect the second grounding point 2, the third grounding point 3, and the fourth grounding point 4, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltage of the first test point 13 and the second test point 14 as the voltage U at the front end of the eighth input shaft. a8 and the voltage U at the rear end of the eighth input shaft b8 Connect the first measuring point 13 to the two sides of the switch corresponding to the fifth grounding point 5, and connect the second measuring point 14 to the two sides of the switch corresponding to the sixth grounding point 6. Disconnect the first grounding point 1, the second grounding point 2, the fifth grounding point 5, and the sixth grounding point 6, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the voltage U at the rear end of the eighth intermediate shaft. d8 and the voltage U at the rear end of the eighth intermediate shaft c8Connect the first measuring point 13 to the two sides of the switch corresponding to the seventh grounding point 7, and connect the second measuring point 14 to the two sides of the switch corresponding to the eighth grounding point 8. Disconnect the first grounding point 1, the second grounding point 2, the seventh grounding point 7, and the eighth grounding point 8, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltage at the first and second measuring points as the voltage U at the front end of the eighth differential shaft. f8 and the voltage U at the rear end of the eighth differential shaft e8 ;

[0134] If the voltage at the front end of the eighth input shaft is U a8 The voltage U at the rear end of the eighth input shaft b8 The voltage U at the rear end of the eighth intermediate shaft d8、 Eighth intermediate shaft rear end voltage U c8 The voltage U at the front end of the eighth differential shaft f8 The voltage U at the rear end of the eighth differential shaft e8 If all values ​​are less than the allowable shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the front end of the motor; otherwise, test mode nine will be performed.

[0135] The test method for Mode 9 is as follows: Connect the first test point 13 to the two sides of the switch corresponding to the third grounding point 3, connect the second test point 14 to the two sides of the switch corresponding to the fourth grounding point, disconnect the first grounding point 1, the third grounding point 3, and the fourth grounding point 4, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltage of the first test point 13 and the second test point 14 as the voltage U at the front end of the ninth input shaft. a9 and the voltage U at the rear end of the ninth input shaft b9 Connect the first measuring point 13 to the two sides of the switch corresponding to the fifth grounding point 5, and connect the second measuring point 14 to the two sides of the switch corresponding to the sixth grounding point 6. Disconnect the first grounding point 1, the second grounding point 2, the fifth grounding point 5, and the sixth grounding point 6, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly to run, and record the voltage at the first measuring point 13 and the second measuring point 14 as the voltage U at the rear end of the ninth intermediate shaft. d9 and the voltage U at the rear end of the ninth intermediate shaft c9 Connect the first measuring point 13 to the two sides of the switch corresponding to the seventh grounding point 7, and connect the second measuring point 14 to the two sides of the switch corresponding to the eighth grounding point 8. Disconnect the first grounding point 1, the second grounding point 2, the seventh grounding point 7, and the eighth grounding point 8, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltage at the first and second measuring points as the voltage U at the front end of the ninth differential shaft. f9 and the voltage U at the rear end of the ninth differential shaft e9 ;

[0136] If the voltage at the front end of the ninth input shaft U a9 The voltage U at the rear end of the ninth input shaft b9 The voltage U at the rear end of the ninth intermediate shaft d9The voltage U at the rear end of the ninth intermediate shaft c9 Voltage U at the front end of the ninth differential shaft f9 Voltage U at the rear end of the ninth differential shaft e9 If all values ​​are less than the allowable shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the rear end of the motor; otherwise, the test of mode ten will be carried out.

[0137] The test method for Mode 10 is as follows: Connect the first test point 13 to the two sides of the switch corresponding to the third grounding point 3, connect the second test point 14 to the two sides of the switch corresponding to the fourth grounding point, disconnect the third grounding point 3 and the fourth grounding point 4, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltage of the first test point 13 and the second test point 14 as the voltage U at the front end of the tenth input shaft. a10 and the voltage U at the rear end of the tenth input shaft b10 Connect the first measuring point 13 to the two sides of the switch corresponding to the fifth grounding point 5, and connect the second measuring point 14 to the two sides of the switch corresponding to the sixth grounding point 6. Disconnect the first grounding point 1, the second grounding point 2, the fifth grounding point 5, and the sixth grounding point 6, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly to run, and record the voltage at the first measuring point 13 and the second measuring point 14 as the voltage U at the rear end of the tenth intermediate shaft. d10 and the voltage U at the rear end of the tenth intermediate shaft c10 Connect the first measuring point 13 to the two sides of the switch corresponding to the seventh grounding point 7, and connect the second measuring point 14 to the two sides of the switch corresponding to the eighth grounding point 8. Disconnect the first grounding point 1, the second grounding point 2, the seventh grounding point 7, and the eighth grounding point 8, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltage at the first and second measuring points as the voltage U at the front end of the tenth differential shaft. f10 and the voltage U at the rear end of the tenth differential shaft e10 ;

[0138] If the voltage at the front end of the tenth input shaft is U a10 The voltage U at the rear end of the tenth input shaft b10 The voltage U at the rear end of the tenth intermediate shaft d10 and the voltage U at the rear end of the tenth intermediate shaft c10 Voltage U at the front end of the tenth differential shaft f10 and the voltage U at the rear end of the tenth differential shaft e10 If the values ​​are all less than the allowable shaft voltage, the electric drive assembly will adopt the countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, the countermeasure will adopt the countermeasure of adding an insulating coating at the bearing in the gearbox that is not less than the allowable shaft voltage.

[0139] In some other embodiments of this application, the above analysis method has been further optimized. Specifically, when it is determined that the bearings of the current electric drive assembly have the risk of electrical corrosion on the motor side and the risk of electrical corrosion on the gearbox side, tests are performed according to mode seven and mode one. If the shaft voltage of all bearing positions in the electric drive assembly measured by mode seven and mode one is less than the allowable value of shaft voltage, then no countermeasures need to be taken; otherwise, tests are performed according to mode eight and mode four.

[0140] If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 8 and Mode 4 are less than the allowable shaft voltage, then the solution of installing a grounding ring at the front end of the motor should be adopted to reduce the shaft voltage; otherwise, the test should be performed according to Mode 9 and Mode 5.

[0141] If the shaft voltages of all bearing positions in the electric drive assembly measured in Modes 9 and 5 are less than the allowable shaft voltage, then a solution of installing a grounding ring at the rear end of the motor should be adopted to reduce the shaft voltage; otherwise, tests should be conducted according to Modes 10 and 6.

[0142] If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 10 and Mode 6 are less than the allowable shaft voltage, then a solution of installing grounding rings at both the front and rear ends of the motor is adopted to reduce the shaft voltage.

[0143] If the bearing shaft voltage is consistently not less than the allowable shaft voltage value in all four modes, the solution is to replace the motor bearing with a ceramic ball bearing or to use an insulating coating to insulate the bearing from the main housing 15 and the shaft in contact with it. Alternatively, the solution is to replace the gearbox bearing with a ceramic ball bearing.

[0144] This application also provides an electric drive assembly shaft voltage testing system, including a grounding point module, a measuring point module, a testing module, and a judgment module. The grounding point module includes a first grounding point 1 and a second grounding point 2 located at both ends of the motor shaft, a third grounding point 3 and a fourth grounding point 4 located at the bearings at both ends of the input shaft 26 assembly, a fifth grounding point 5 and a sixth grounding point 6 located at the bearings at both ends of the intermediate shaft 29 assembly, a seventh grounding point 7 and an eighth grounding point located at the bearings at both ends of the differential 31 assembly, a ninth grounding point 9 and a tenth grounding point 10 located at the bearings at both ends of the motor shaft, and an eleventh grounding point 11 located on the main housing 15 of the electric drive assembly. The measuring point module includes a first measuring point 13 and a second measuring point 14 located at both ends of the motor shaft. The testing module achieves different testing modes by controlling the on / off state of the eleven grounding points and records the voltages of the first measuring point 13 and the second measuring point 14 under each testing mode as the front shaft voltage and the rear shaft voltage of the motor, respectively. The judgment module analyzes and judges whether corresponding countermeasures need to be formulated for the electric drive assembly based on the front shaft voltage and the rear shaft voltage of the motor.

[0145] The testing module includes a first module, a second module, a third module, a fourth module, a fifth module, a sixth module, a seventh module, an eighth module, a ninth module, and a tenth module. The first module implements the Mode 1 testing method by disconnecting the first grounding point 1 and the second grounding point 2 and connecting the remaining grounding points, and records the voltages at the first measuring point 13 and the second measuring point 14 under the Mode 1 testing method as the front-end voltage and the rear-end voltage of the first motor. The second module implements the Mode 2 testing method by connecting the ninth grounding point 9, the tenth grounding point 10, and the eleventh grounding point 11 and disconnecting the remaining grounding points, and records the voltage at the first measuring point 13 under the Mode 2 testing method. The voltage at the second measuring point 14 is the voltage at the front end of the second motor and the voltage at the rear end of the second motor. The third module implements the mode three test method by disconnecting the first grounding point 1, the second grounding point 2, the ninth grounding point 9, and the tenth grounding point 10 and connecting the remaining grounding points, and records the voltage at the first measuring point 13 and the voltage at the second measuring point 14 under the mode three test method as the voltage at the front end of the third motor and the voltage at the rear end of the third motor. The fourth module implements the mode four test method by connecting the first grounding point 1, the ninth grounding point 9, the tenth grounding point 10, and the eleventh grounding point 11 and disconnecting the remaining grounding points, and records the voltage at the first measuring point 13 and the voltage at the second measuring point 14 under the mode four test method. The voltages at the front and rear ends of the fourth motor are recorded. The fifth module implements the Mode 5 test method by connecting the second grounding point 2, the ninth grounding point 9, the tenth grounding point 10, and the eleventh grounding point 11 while disconnecting the remaining grounding points. The voltages at the first measuring point 13 and the second measuring point 14 under the Mode 5 test method are recorded as the front and rear ends of the fifth motor, respectively. The sixth module implements the Mode 6 test method by connecting the first grounding point 1, the second grounding point 2, the ninth grounding point 9, the tenth grounding point 10, and the eleventh grounding point 11 while disconnecting the remaining grounding points. The voltages at the first measuring point 13 and the second measuring point 14 under the Mode 6 test method are recorded. The voltage at 4 is the front voltage of the sixth motor and the rear voltage of the sixth motor; the seventh module connects the first measuring point 13 to the two sides of the switch corresponding to the third grounding point 3, connects the second measuring point 14 to the two sides of the switch corresponding to the fourth grounding point, disconnects the first grounding point 1, the second grounding point 2, the third grounding point 3 and the fourth grounding point 4, and connects the remaining grounding points to realize the mode seven test method, and records the voltages of the first measuring point 13 and the second measuring point 14 under the mode seven test method as the front voltage of the seventh input shaft, the rear voltage of the seventh input shaft, the front voltage of the seventh intermediate shaft, the rear voltage of the seventh intermediate shaft, the front voltage of the seventh differential shaft and the rear voltage of the seventh differential shaft;The eighth module connects the first measuring point 13 to the two sides of the switch corresponding to the third grounding point 3, connects the second measuring point 14 to the two sides of the switch corresponding to the fourth grounding point, disconnects the second grounding point 2, the third grounding point 3, and the fourth grounding point 4, and connects the remaining grounding points to realize the Mode 8 test method. It records the voltages of the first measuring point 13 and the second measuring point 14 under the Mode 8 test method as the voltage at the front end of the eighth input shaft, the voltage at the rear end of the eighth input shaft, the voltage at the front end of the eighth intermediate shaft, the voltage at the rear end of the eighth intermediate shaft, the voltage at the front end of the eighth differential shaft, and the voltage at the rear end of the eighth differential shaft. The ninth module connects the first measuring point 13 to the two sides of the switch corresponding to the third grounding point 3, connects the second measuring point 14 to the two sides of the switch corresponding to the fourth grounding point, disconnects the first grounding point 1, the third grounding point 3, and the fourth grounding point 4, and connects the remaining grounding points to realize the Mode 8 test method. The ninth test method is used, and the voltages at the first test point 13 and the second test point 14 under the ninth test method are recorded as the voltage at the front end of the ninth input shaft, the voltage at the rear end of the ninth input shaft, the voltage at the front end of the ninth intermediate shaft, the voltage at the rear end of the ninth intermediate shaft, the voltage at the front end of the ninth differential shaft, and the voltage at the rear end of the ninth differential shaft. The tenth module connects the first test point 13 to the two sides of the switch corresponding to the third grounding point 3, connects the second test point 14 to the two sides of the switch corresponding to the fourth grounding point, disconnects the third grounding point 3 and the fourth grounding point 4, and connects the remaining grounding points to realize the tenth test method, and records the voltages at the first test point 13 and the second test point 14 under the tenth test method as the voltage at the front end of the tenth input shaft, the voltage at the rear end of the tenth input shaft, the voltage at the front end of the tenth intermediate shaft, the voltage at the rear end of the tenth intermediate shaft, the voltage at the front end of the tenth differential shaft, and the voltage at the rear end of the tenth differential shaft.

[0146] The judgment module includes a no-corrosion-risk judgment module, a motor-side no-corrosion-risk judgment module, a gearbox-side corrosion-risk judgment module, and a two-sided corrosion-risk judgment module. The no-corrosion-risk judgment module determines that the risk of electro-corrosion of the bearings in the current electric drive assembly is low and no countermeasures are needed when the waveforms of the voltages at the front and rear ends of the first, second, and third motors are all common-mode waveforms. The motor-side no-corrosion-risk judgment module determines that the bearings in the current electric drive assembly have a risk of motor-side electro-corrosion when the waveforms of the voltages at the front and rear ends of the first, second, and second motors are all breakdown waveforms, and the waveforms of the voltages at the front and rear ends of the third motor are common-mode waveforms. The pressure is further assessed, and corresponding countermeasures are made. When the waveforms of the voltage at the front end of the second motor and the voltage at the rear end of the second motor are common-mode waveforms, and the waveforms of the voltage at the front end of the first motor, the voltage at the rear end of the first motor, the voltage at the front end of the third motor, and the voltage at the rear end of the third motor are breakdown waveforms, the bearing of the current electric drive assembly is deemed to have a risk of electrical corrosion on the gearbox side, requiring further assessment based on the voltage and corresponding countermeasures. When the waveforms of the voltage at the front end of the first motor, the voltage at the rear end of the first motor, the voltage at the front end of the second motor, the voltage at the rear end of the second motor, the voltage at the front end of the third motor, and the voltage at the rear end of the third motor are all breakdown waveforms, the bearing of the current electric drive assembly is deemed to have a risk of electrical corrosion on both the gearbox side and the motor side, requiring further assessment based on the voltage and corresponding countermeasures.

[0147] The judgment module also includes a no-countermeasure formulation module, a fourth countermeasure formulation module, a fifth countermeasure formulation module, a sixth countermeasure formulation module, a seventh countermeasure formulation module, an eighth countermeasure formulation module, a ninth countermeasure formulation module, a tenth countermeasure formulation module, and an eleventh countermeasure formulation module. The no-countermeasure formulation module is used to determine that the current bearing has a low risk of electrical corrosion on the motor side and / or on the gearbox side when the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side, and the voltages at the front and rear ends of the first, second, third, and third motors are all less than the allowable shaft voltage value, thus determining that no countermeasures are needed. The fourth countermeasure formulation module is used to further determine the risk of electrical corrosion on the bearing of the current electric drive assembly when the bearing has a risk of electrical corrosion on the motor side, and the voltages at the front and rear ends of the first, second, third, and third motors do not all meet the condition of being less than the allowable shaft voltage value, based on the voltages at the front and rear ends of the fourth motor collected by the mode four testing method. The system determines whether, when both the front-end voltage and the rear-end voltage of the fourth motor are less than the allowable shaft voltage, a countermeasure is formulated to add a grounding ring at the front end of the motor. The fifth countermeasure formulation module, when the condition that both the front-end voltage and the rear-end voltage of the fourth motor are less than the allowable shaft voltage is not met, further determines whether, based on the voltages collected by the mode five test method, a countermeasure is formulated to add a grounding ring at the rear end of the motor. The sixth countermeasure formulation module, when the condition that both the front-end voltage and the rear-end voltage of the fifth motor are less than the allowable shaft voltage is not met, further determines whether, based on the voltages collected by the mode six test method, a countermeasure is formulated to add grounding rings at both the front and rear ends of the motor. Otherwise, a countermeasure is formulated to replace all bearings in the electric drive assembly with ceramic ball bearings or to use an insulating coating to insulate the bearings from the main housing 15 and the shaft in contact with them.The seventh countermeasure formulation module is used to further determine the risk of gearbox-side electrolytic corrosion in the bearings of the current electric drive assembly, and to further determine the risk when the voltages of the first motor front end, first motor rear end, second motor front end, second motor rear end, third motor front end, and third motor rear end are all less than the allowable shaft voltage. This is based on the seventh input shaft front end voltage, seventh input shaft rear end voltage, seventh intermediate shaft front end voltage, seventh intermediate shaft rear end voltage, seventh differential shaft front end voltage, and seventh differential shaft rear end voltage collected by the mode seven test method. When the voltages at the rear end of the input shaft, the front and rear ends of the seventh intermediate shaft, the front and rear ends of the seventh differential shaft, and both the front and rear ends of the seventh differential shaft are all less than the allowable shaft voltage values, a judgment is made that no countermeasures need to be formulated for the gearbox bearings of the electric drive assembly. The eighth countermeasure formulation module is used to determine, based on the voltages at the front and rear ends of the eighth input shaft acquired using the mode eight test method, that when the conditions are not met (the voltages at the front and rear ends of the seventh input shaft, the front and rear ends of the seventh intermediate shaft, and both the front and rear ends of the seventh differential shaft are all less than the allowable shaft voltage values), that no countermeasures need to be formulated for the gearbox bearings of the electric drive assembly. The system further assesses the voltage at the front and rear ends of the eighth intermediate shaft, the front and rear ends of the eighth differential shaft, and the rear ends of the eighth differential shaft. If all voltages at the front and rear ends of the eighth input shaft, the eighth intermediate shaft, and the eighth differential shaft are less than the allowable shaft voltage values, a countermeasure is devised to add a grounding ring at the front end of the motor. The ninth countermeasure formulation module is used to determine if the voltages at the front and rear ends of the eighth input shaft, the eighth intermediate shaft, and the eighth differential shaft are all less than the allowable shaft voltage values. When both the front-end voltage of the eighth differential shaft and the rear-end voltage of the eighth differential shaft are less than the allowable value of the shaft voltage, further judgment is made based on the front-end voltage of the ninth input shaft, the rear-end voltage of the ninth input shaft, the front-end voltage of the ninth intermediate shaft, the rear-end voltage of the ninth intermediate shaft, the front-end voltage of the ninth differential shaft, and the rear-end voltage of the ninth differential shaft collected by the mode nine test method. When both the front-end voltage of the ninth input shaft, the rear-end voltage of the ninth input shaft, the front-end voltage of the ninth intermediate shaft, the rear-end voltage of the ninth intermediate shaft, and the front-end voltage of the ninth differential shaft are less than the allowable value of the shaft voltage, a countermeasure of adding a grounding ring at the rear end of the motor is formulated.The tenth countermeasure formulation module is used to further determine the following conditions when the voltages of the ninth input shaft front end, ninth input shaft rear end, ninth intermediate shaft front end and rear end, and ninth differential shaft front end and rear end are all less than the allowable shaft voltage value: based on the voltages of the tenth input shaft front end and rear end, tenth intermediate shaft front end and rear end, and tenth differential shaft front end and rear end collected by the mode ten test method. If the voltages of the tenth input shaft front end and rear end, tenth intermediate shaft front end and rear end, and tenth differential shaft front end and rear end are all less than the allowable shaft voltage value, the module formulates a countermeasure by adding grounding rings at both ends of the motor; otherwise, it formulates a countermeasure by adding grounding rings at both ends of the motor within the electric drive assembly. The countermeasure is to add an insulating coating to the bearing at the allowable shaft voltage value; the eleventh countermeasure formulation module is used to further judge the first motor front end voltage, first motor rear end voltage, seventh input shaft front end voltage, seventh input shaft rear end voltage, seventh intermediate shaft front end voltage, seventh intermediate shaft rear end voltage, seventh differential shaft front end voltage and seventh differential shaft rear end voltage when the bearing of the current electric drive assembly has the risk of electrical corrosion on the motor side and the gearbox side, based on the test methods of mode one and mode seven. When the first motor front end voltage, first motor rear end voltage, seventh input shaft front end voltage, seventh input shaft rear end voltage, seventh intermediate shaft front end voltage, seventh intermediate shaft rear end voltage, seventh differential shaft front end voltage and seventh differential shaft rear end voltage are all less than the allowable shaft voltage value, it makes a judgment that no countermeasures need to be formulated for the bearing of the electric drive assembly;

[0148] Based on the test methods of Mode 4 and Mode 8, further judgments are made on the voltages of the fourth motor front end, fourth motor rear end, eighth input shaft front end, eighth input shaft rear end, eighth intermediate shaft front end and rear end, eighth differential shaft front end and rear end. When the voltages of the fourth motor front end, fourth motor rear end, eighth input shaft front end and rear end, eighth intermediate shaft front end and rear end, and eighth differential shaft front end and rear end are all less than the allowable shaft voltage values, a countermeasure of adding a grounding ring at the front end of the motor is formulated.

[0149] Based on the voltages collected using the Mode 5 and Mode 9 test methods, further judgments are made regarding the voltages at the front and rear ends of the fifth motor, the ninth input shaft, the ninth intermediate shaft, and the ninth differential shaft. When all the voltages at the front and rear ends of the fifth motor, the ninth input shaft, the ninth intermediate shaft, and the ninth differential shaft are less than the allowable shaft voltage values, a countermeasure is proposed to add a grounding ring at the front end of the motor.

[0150] Based on the voltages collected using the Mode 6 and Mode 10 test methods, further judgments are made on the voltages at the front and rear ends of the sixth motor, the tenth input shaft, the tenth intermediate shaft, and the tenth differential shaft. When all the voltages at the front and rear ends of the sixth motor, the tenth input shaft, the tenth intermediate shaft, and the tenth differential shaft are less than the allowable shaft voltage values, a countermeasure of adding a grounding ring at the front end of the motor is formulated.

[0151] If the bearing shaft voltage is consistently not less than the allowable shaft voltage value in all four modes, a countermeasure will be formulated to replace the motor bearing with a ceramic ball bearing or to use an insulating coating to insulate the bearing from the main housing 15 and the shaft in contact with it. A countermeasure will also be formulated to replace the gearbox bearing with a ceramic ball bearing.

[0152] like Figure 1 and 2 As shown, the front end of this embodiment refers to... Figure 1 and 2 The left side, the back end refers to Figure 1 and 2 On the right side.

[0153] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A method for testing shaft voltage of an electric drive assembly, characterized in that: Includes the following steps, Grounding points are arranged on the electric drive assembly, including a first grounding point and a second grounding point located at both ends of the motor shaft, a third grounding point and a fourth grounding point located at the bearings at both ends of the input shaft assembly, a fifth grounding point and a sixth grounding point located at the bearings at both ends of the intermediate shaft assembly, a seventh grounding point and an eighth grounding point located at the bearings at both ends of the differential assembly, a ninth grounding point and a tenth grounding point located at the bearings at both ends of the motor shaft, and an eleventh grounding point located on the main housing of the electric drive assembly. A first measuring point and a second measuring point are arranged at both ends of the motor shaft; Different test modes are achieved by controlling the on / off state of eleven grounding points. The electric drive assembly is driven by a bench, and the voltage of the first and second test points is recorded in each test mode. Analyze the voltages of the first and second test points under each recorded test mode to determine whether corresponding countermeasures need to be developed for the electric drive assembly; The method for controlling the on / off state of the eleven grounding points to achieve different test modes includes: Mode 1: Disconnect the first and second grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages at the first and second measuring points as the voltage at the front end and rear end of the first motor, respectively. Mode 2: Connect the ninth, tenth, and eleventh grounding points, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages at the first and second measuring points as the voltages at the front and rear ends of the second motor. Mode 3: Disconnect the first, second, ninth, and tenth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages at the first and second measuring points as the voltage at the front end and rear end of the third motor. The method for analyzing the voltages of the first and second test points under each recorded test mode includes: if the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, the second motor rear end voltage, the third motor front end voltage, and the third motor rear end voltage are all common-mode waveforms, it is determined that the risk of electro-corrosion of the bearings of the current electric drive assembly is low, and no countermeasures need to be formulated. If the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, and the second motor rear end voltage are all breakdown waveforms, and the waveforms of the third motor front end voltage and the third motor rear end voltage are common mode waveforms, it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the motor side. Further judgment based on the voltage is needed and corresponding countermeasures should be taken. If the waveforms of the front-end voltage of the second motor and the rear-end voltage of the second motor are common-mode waveforms, and the waveforms of the front-end voltage of the first motor, the rear-end voltage of the first motor, the front-end voltage of the third motor, and the rear-end voltage of the third motor are breakdown waveforms, it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the gearbox side. Further judgment based on the voltage is needed and corresponding countermeasures should be taken. If the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, the second motor rear end voltage, the third motor front end voltage, and the third motor rear end voltage are all breakdown waveforms, it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the gearbox side and the motor side. Further judgment and corresponding countermeasures are needed based on the voltage.

2. The method for testing shaft voltage of an electric drive assembly as described in claim 1, characterized in that: The method for arranging grounding points on the electric drive assembly includes: arranging lead wires at each grounding point, with one end of the lead wire passing through the main housing to enter the insulating base at the grounding point and connecting to the corresponding grounding point, and the other end connecting to the grounding wire, and a switch arranged on the lead wire.

3. The method for testing shaft voltage of an electric drive assembly as described in claim 1, characterized in that: When it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the motor side and / or on the gearbox side, if the voltages at the front end of the first motor, the rear end of the first motor, the front end of the second motor, the rear end of the second motor, the front end of the third motor, and the rear end of the third motor are all less than the allowable value of the shaft voltage, then the current bearing electrical corrosion risk is low and no countermeasures need to be formulated. Otherwise, it is necessary to make further judgments based on the voltage and formulate corresponding countermeasures.

4. The method for testing shaft voltage of an electric drive assembly as described in claim 3, characterized in that: When determining that the bearings of the current electric drive assembly have a risk of electrical corrosion on the motor side, if the voltages at the front and rear ends of the first motor, the second motor, the third motor, and the third motor are all less than the allowable value of the shaft voltage, test mode four is performed. The test method for mode four is as follows: connect the first, ninth, tenth, and eleventh grounding points, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages at the first and second test points as the voltages at the front and rear ends of the fourth motor. If both the front-end voltage and the rear-end voltage of the fourth motor are less than the allowable value of the shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the front end of the motor; otherwise, the test of mode five will be carried out. The test method for mode five is as follows: connect the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly to run, and record the voltages at the first and second test points as the front voltage and rear voltage of the fifth motor. If both the front-end voltage and the rear-end voltage of the fifth motor are less than the allowable shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the rear end of the motor; otherwise, the test of mode six will be performed. The test method for Mode 6 is as follows: connect the first grounding point, the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnect the remaining grounding points, use a test bench to drive the electric drive assembly to run, and record the voltages at the first and second test points as the front voltage and rear voltage of the sixth motor. If both the front-end voltage and the rear-end voltage of the sixth motor are less than the allowable shaft voltage, the electric drive assembly adopts the countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, the countermeasure is to replace all the bearings of the electric drive assembly with ceramic ball bearings or to use an insulating coating to insulate the bearings from the housing and shaft in contact with them.

5. The method for testing shaft voltage of an electric drive assembly as described in claim 3, characterized in that: When determining that the bearings of the current electric drive assembly have a risk of electro-corrosion on the gearbox side, if the voltages at the front and rear ends of the first motor, the second motor, the third motor, and the third motor are all less than the allowable shaft voltage value, test mode seven is performed. The test method for mode seven is as follows: connect the two sides of the switch corresponding to the first test point and the third grounding point, connect the two sides of the switch corresponding to the second test point and the fourth grounding point, disconnect the first, second, third, and fourth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages at the first and second test points as the voltages at the front and rear ends of the seventh input shaft; Connect the two sides of the switch corresponding to the fifth grounding point, connect the two sides of the switch corresponding to the sixth grounding point, disconnect the first, second, fifth, and sixth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the seventh intermediate shaft; connect the two sides of the switch corresponding to the seventh grounding point, connect the two sides of the switch corresponding to the eighth grounding point, disconnect the first, second, seventh, and eighth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the seventh differential shaft; If the voltage at the front end of the seventh input shaft, the voltage at the rear end of the seventh input shaft, the voltage at the front end of the seventh intermediate shaft, the voltage at the rear end of the seventh intermediate shaft, the voltage at the front end of the seventh differential shaft, and the voltage at the rear end of the seventh differential shaft are all less than the allowable value of the shaft voltage, then it is determined that the risk of electro-corrosion of the bearings at both ends of the axial direction of the current electric drive assembly input shaft assembly is low, and no countermeasures are required; otherwise, test mode eight is performed. The test method for Mode 8 is as follows: Connect the two sides of the switch corresponding to the first test point and the third grounding point, connect the two sides of the switch corresponding to the second test point and the fourth grounding point, disconnect the second, third, and fourth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the eighth input shaft; connect the two sides of the switch corresponding to the first test point and the fifth grounding point, connect the two sides of the switch corresponding to the second test point and the sixth grounding point, disconnect the second, fifth, and sixth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the eighth intermediate shaft; connect the two sides of the switch corresponding to the first test point and the seventh grounding point, connect the two sides of the switch corresponding to the eighth grounding point, disconnect the second, seventh, and eighth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the eighth differential shaft; If the voltage at the front end of the eighth input shaft, the voltage at the rear end of the eighth input shaft, the voltage at the front end of the eighth intermediate shaft, the voltage at the rear end of the eighth intermediate shaft, the voltage at the front end of the eighth differential shaft, and the voltage at the rear end of the eighth differential shaft are all less than the allowable value of the shaft voltage, the electric drive assembly will adopt the countermeasure of adding a grounding ring at the front end of the motor; otherwise, the test of mode nine will be performed. The test method for Mode Nine is as follows: Connect the two sides of the switch corresponding to the first test point and the third grounding point, connect the two sides of the switch corresponding to the second test point and the fourth grounding point, disconnect the first, third, and fourth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the ninth input shaft; connect the two sides of the switch corresponding to the first test point and the fifth grounding point, connect the two sides of the switch corresponding to the second test point and the sixth grounding point, disconnect the first, fifth, and sixth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the ninth intermediate shaft; connect the two sides of the switch corresponding to the first test point and the seventh grounding point, connect the two sides of the switch corresponding to the second test point and the eighth grounding point, disconnect the first, seventh, and eighth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the ninth differential shaft; If the voltage at the front end of the ninth input shaft, the voltage at the rear end of the ninth input shaft, the voltage at the front end of the ninth intermediate shaft, the voltage at the rear end of the ninth intermediate shaft, the voltage at the front end of the ninth differential shaft, and the voltage at the rear end of the ninth differential shaft are all less than the allowable value of the shaft voltage, the electric drive assembly adopts the countermeasure of adding a grounding ring at the rear end of the motor; otherwise, the test of mode ten is performed. The test method for Mode 10 is as follows: Connect the first test point to both sides of the switch corresponding to the third grounding point, connect the second test point to both sides of the switch corresponding to the fourth grounding point, disconnect the third and fourth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the tenth input shaft; connect the first test point to both sides of the switch corresponding to the fifth grounding point, connect the second test point to both sides of the switch corresponding to the sixth grounding point, disconnect the fifth and sixth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the tenth intermediate shaft; connect the first test point to both sides of the switch corresponding to the seventh grounding point, connect the second test point to both sides of the switch corresponding to the eighth grounding point, disconnect the seventh and eighth grounding points, connect the remaining grounding points, use a test bench to drive the electric drive assembly, and record the voltages of the first and second test points as the voltage at the front end and rear end of the tenth differential shaft; If the voltage at the front end of the tenth input shaft, the voltage at the rear end of the tenth input shaft, the voltage at the front end of the tenth intermediate shaft, the voltage at the rear end of the tenth intermediate shaft, the voltage at the front end of the tenth differential shaft, and the voltage at the rear end of the tenth differential shaft are all less than the allowable shaft voltage, then the electric drive assembly adopts the countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, the countermeasure is to add an insulating coating at the bearing in the gearbox that is not less than the allowable shaft voltage.

6. The method for testing shaft voltage of an electric drive assembly as described in claim 5, characterized in that: When determining that the bearings of the current electric drive assembly have the risk of electrical corrosion on the motor side and the gearbox side, test according to Mode 7 and Mode 1. If the shaft voltage of all bearing positions in the electric drive assembly measured by Mode 7 and Mode 1 is less than the allowable shaft voltage value, no countermeasures are required; otherwise, test according to Mode 8 and Mode 4. If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 8 and Mode 4 are less than the allowable shaft voltage, then the solution of installing a grounding ring at the front end of the motor should be adopted to reduce the shaft voltage; otherwise, the test should be performed according to Mode 9 and Mode 5. If the shaft voltages of all bearing positions in the electric drive assembly measured in Modes 9 and 5 are less than the allowable shaft voltage, then a solution of installing a grounding ring at the rear end of the motor should be adopted to reduce the shaft voltage; otherwise, tests should be conducted according to Modes 10 and 6. If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 10 and Mode 6 are less than the allowable shaft voltage, then a solution of installing grounding rings at both the front and rear ends of the motor is adopted to reduce the shaft voltage. If the bearing shaft voltage is consistently not less than the allowable shaft voltage value in all four modes, the following countermeasures are adopted: replacing the motor bearing in the electric drive assembly with a ceramic ball bearing or using an insulating coating to insulate the bearing from the housing and shaft in contact with it; and replacing the gearbox bearing in the electric drive assembly with a ceramic ball bearing.

7. A shaft voltage testing system for an electric drive assembly, characterized in that: The testing system is operated according to any of the electric drive assembly shaft voltage testing methods as described in claims 1 to 6, including: The grounding module includes a first grounding point and a second grounding point located at both ends of the motor shaft, a third grounding point and a fourth grounding point located at the bearings at both ends of the input shaft assembly, a fifth grounding point and a sixth grounding point located at the bearings at both ends of the intermediate shaft assembly, a seventh grounding point and an eighth grounding point located at the bearings at both ends of the differential assembly, a ninth grounding point and a tenth grounding point located at the bearings at both ends of the motor shaft, and an eleventh grounding point located on the main housing of the electric drive assembly. The measuring point module includes a first measuring point and a second measuring point located at both ends of the motor shaft. The test module controls the on / off state of eleven grounding points to achieve different test modes and records the voltage of the first and second test points under each test mode. The judgment module analyzes and determines whether corresponding countermeasures need to be formulated for the electric drive assembly based on the voltage of the first and second test points under each test mode.

8. The electric drive assembly shaft voltage testing system as described in claim 7, characterized in that: The test module includes, The first module implements the Mode 1 test method by disconnecting the first grounding point and the second grounding point and connecting the remaining grounding points, and records the voltages of the first test point and the second test point under the Mode 1 test method as the front-end voltage and the rear-end voltage of the first motor. The second module implements the Mode 2 test method by connecting the ninth, tenth, and eleventh grounding points and disconnecting the remaining grounding points, and records the voltages of the first and second test points under the Mode 2 test method as the front-end voltage of the second motor and the rear-end voltage of the second motor. The third module implements the mode three test method by disconnecting the first grounding point, the second grounding point, the ninth grounding point, and the tenth grounding point and connecting the remaining grounding points, and records the voltages of the first and second test points under the mode three test method as the front-end voltage and the rear-end voltage of the third motor. The fourth module implements the Mode 4 test method by connecting the first grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point and disconnecting the remaining grounding points, and records the voltages of the first and second test points under the Mode 4 test method as the front-end voltage and the rear-end voltage of the fourth motor. The fifth module implements the mode five test method by connecting the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point and disconnecting the remaining grounding points, and records the voltages of the first and second test points under the mode five test method as the front-end voltage and the rear-end voltage of the fifth motor. The sixth module implements the Mode 6 test method by connecting the first grounding point, the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point and disconnecting the remaining grounding points, and records the voltages of the first and second test points under the Mode 6 test method as the front-end voltage and the rear-end voltage of the sixth motor. The seventh module connects the first test point to the switch corresponding to the third grounding point, connects the second test point to the switch corresponding to the fourth grounding point, disconnects the first, second, third, and fourth grounding points, and connects the remaining grounding points to implement the mode seven test method. It records the voltages at the first and second test points under the mode seven test method as the front and rear voltages of the seventh input shaft. It then connects the first test point to the switch corresponding to the fifth grounding point, connects the second test point to the switch corresponding to the sixth grounding point, and disconnects the first and second grounding points. Connect the fifth and sixth grounding points, and the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltages at the first and second measuring points as the voltage at the front and rear ends of the seventh intermediate shaft. Connect the first measuring point to the switch corresponding to the seventh grounding point on both sides, and connect the second measuring point to the switch corresponding to the eighth grounding point on both sides. Disconnect the first, second, seventh, and eighth grounding points, and connect the remaining grounding points. Use a test bench to drive the electric drive assembly and record the voltages at the first and second measuring points as the voltage at the front and rear ends of the seventh differential shaft. The eighth module implements the Mode 8 test method by connecting the first test point to the two sides of the switch corresponding to the third grounding point, connecting the second test point to the two sides of the switch corresponding to the fourth grounding point, disconnecting the second, third, and fourth grounding points, and connecting the remaining grounding points. It records the voltages of the first and second test points under the Mode 8 test method as the front and rear voltages of the eighth input shaft. The module further connects the first test point to the two sides of the switch corresponding to the fifth grounding point, connects the second test point to the two sides of the switch corresponding to the sixth grounding point, disconnects the second, fifth, and sixth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the front and rear voltages of the eighth intermediate shaft. Finally, it connects the first test point to the two sides of the switch corresponding to the seventh grounding point, connects the second test point to the two sides of the switch corresponding to the eighth grounding point, disconnects the second, seventh, and eighth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the front and rear voltages of the eighth differential shaft. The ninth module implements the Mode 9 test method by connecting the first test point to the switch corresponding to the third grounding point, connecting the second test point to the switch corresponding to the fourth grounding point, disconnecting the first, third, and fourth grounding points, and connecting the remaining grounding points. It records the voltages of the first and second test points as the front and rear voltages of the ninth input shaft under the Mode 9 test method. The module further connects the first test point to the switch corresponding to the fifth grounding point, connects the second test point to the switch corresponding to the sixth grounding point, disconnects the first, fifth, and sixth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the front and rear voltages of the ninth intermediate shaft. Finally, it connects the first test point to the switch corresponding to the seventh grounding point, connects the second test point to the switch corresponding to the eighth grounding point, disconnects the first, seventh, and eighth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the front and rear voltages of the ninth differential shaft. The tenth module implements the Mode 10 test method by connecting the first test point to the two sides of the switch corresponding to the third grounding point, connecting the second test point to the two sides of the switch corresponding to the fourth grounding point, disconnecting the third and fourth grounding points, and connecting the remaining grounding points. The module records the voltages of the first and second test points under Mode 10 as the voltage at the front and rear ends of the tenth input shaft. It then connects the first test point to the two sides of the switch corresponding to the fifth grounding point, connects the second test point to the two sides of the switch corresponding to the sixth grounding point, disconnects the fifth and sixth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the voltage at the front and rear ends of the tenth intermediate shaft. Finally, it connects the first test point to the two sides of the switch corresponding to the seventh grounding point, connects the second test point to the two sides of the switch corresponding to the eighth grounding point, disconnects the seventh and eighth grounding points, connects the remaining grounding points, and uses a test bench to drive the electric drive assembly, recording the voltages of the first and second test points as the voltage at the front and rear ends of the tenth differential shaft.

9. The electric drive assembly shaft voltage testing system as described in claim 8, characterized in that: The judgment module includes, The corrosion risk assessment module determines that the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, the second motor rear end voltage, the third motor front end voltage, and the third motor rear end voltage are all common-mode waveforms, and therefore makes the judgment that the risk of electro-corrosion of the bearings in the current electric drive assembly is low and no countermeasures need to be formulated. The motor-side corrosion risk assessment module determines that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side when the waveforms of the first motor front end voltage, the first motor rear end voltage, the second motor front end voltage, and the second motor rear end voltage are all breakdown waveforms, and the waveforms of the third motor front end voltage and the third motor rear end voltage are common mode waveforms. It then makes a judgment that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side and needs to be further judged in combination with the voltage and corresponding countermeasures should be made. The gearbox-side corrosion risk assessment module determines that when the waveforms of the voltage at the front end of the second motor and the voltage at the rear end of the second motor are common-mode waveforms, and the waveforms of the voltage at the front end of the first motor, the voltage at the rear end of the first motor, the voltage at the front end of the third motor, and the voltage at the rear end of the third motor are breakdown waveforms, it determines that the bearing of the current electric drive assembly has a risk of gearbox-side electrical corrosion, and further judgment needs to be made in conjunction with the voltage and corresponding countermeasures should be taken. The dual-side corrosion risk assessment module determines that when the waveforms of the voltage at the front end of the first motor, the rear end of the first motor, the front end of the second motor, the rear end of the second motor, the front end of the third motor, and the rear end of the third motor are all breakdown waveforms, the module determines that the bearings of the current electric drive assembly have a risk of electrical corrosion on both the gearbox side and the motor side, and that further assessment based on the voltage is needed to determine appropriate countermeasures.

10. The electric drive assembly shaft voltage testing system as described in claim 9, characterized in that: The judgment module also includes, No countermeasure formulation module, which is used to determine that the current bearing has low electrical corrosion risk and / or gearbox side electrical corrosion risk when it is determined that the bearing of the current electric drive assembly has low electrical corrosion risk and no countermeasure needs to be formulated. The fourth countermeasure formulation module is used to further determine the risk of motor-side electrical corrosion of the bearings of the current electric drive assembly and to formulate a countermeasure of adding a grounding ring at the front end of the motor when it is determined that the bearings of the current electric drive assembly have a risk of electrical corrosion on the motor side and the front end voltages of the first motor, the second motor, the second motor, the third motor, and the third motor are all less than the allowable value of the shaft voltage. The fifth countermeasure formulation module is used to make further judgments based on the fifth motor front-end voltage and fifth motor rear-end voltage collected by the mode five test method when the condition that the fourth motor front-end voltage and the fourth motor rear-end voltage are both less than the allowable value of the shaft voltage is not met. When the fifth motor front-end voltage and the fifth motor rear-end voltage are both less than the allowable value of the shaft voltage, the module formulates a countermeasure to add a grounding ring at the motor rear end. The sixth countermeasure formulation module is used to further determine the sixth motor front-end voltage and sixth motor rear-end voltage based on the test method of mode six when the condition that the fifth motor front-end voltage and the fifth motor rear-end voltage are both less than the allowable shaft voltage is not met. If the sixth motor front-end voltage and the sixth motor rear-end voltage are both less than the allowable shaft voltage, the module formulates a countermeasure to add grounding rings at both ends of the motor. Otherwise, the module formulates a countermeasure to replace all bearings of the electric drive assembly with ceramic ball bearings or to use an insulating coating to insulate the bearings from the housing and shaft they contact.

11. The electric drive assembly shaft voltage testing system as described in claim 9, characterized in that: The judgment module also includes, The seventh countermeasure formulation module is used to further determine, based on the seventh input shaft front voltage, seventh input shaft rear voltage, seventh intermediate shaft front voltage, seventh intermediate shaft rear voltage, seventh differential shaft front voltage, and seventh differential shaft rear voltage collected by the mode seven test method, when it is determined that there is a risk of gearbox-side electrical corrosion in the bearing of the current electric drive assembly and the first motor front voltage, first motor rear voltage, second motor front voltage, second motor rear voltage, third motor front voltage, and third motor rear voltage are all less than the allowable shaft voltage value. When the seventh input shaft front voltage, seventh input shaft rear voltage, seventh intermediate shaft front voltage, seventh intermediate shaft rear voltage, seventh differential shaft front voltage, and seventh differential shaft rear voltage are all less than the allowable shaft voltage value, it makes a judgment that no countermeasures need to be formulated for the gearbox bearing of the electric drive assembly. The eighth countermeasure formulation module is used to further determine the voltages of the eighth input shaft front end, eighth input shaft rear end, seventh intermediate shaft front end, seventh intermediate shaft rear end, seventh differential shaft front end, and seventh differential shaft rear end when the conditions are not met (all of these voltages are less than the allowable shaft voltage value). Based on the voltages of the eighth input shaft front end, eighth input shaft rear end, eighth intermediate shaft front end, eighth intermediate shaft rear end, eighth differential shaft front end, and eighth differential shaft rear end collected by the mode eight test method, the module formulates a countermeasure to add a grounding ring at the front end of the motor when all of these voltages are less than the allowable shaft voltage value. The ninth countermeasure formulation module is used to further determine the voltages of the ninth input shaft front end, eighth input shaft rear end, eighth intermediate shaft front end, eighth intermediate shaft rear end, eighth differential shaft front end, and eighth differential shaft rear end when the conditions are not met (all of these voltages are less than the allowable shaft voltage value). Based on the voltages of the ninth input shaft front end, ninth input shaft rear end, ninth intermediate shaft front end, ninth intermediate shaft rear end, ninth differential shaft front end, and ninth differential shaft rear end, the module further determines the countermeasure of adding a grounding ring at the rear end of the motor when all of these voltages are less than the allowable shaft voltage value. The tenth countermeasure formulation module is used to further determine the following conditions when the voltages of the ninth input shaft front end, the ninth input shaft rear end, the ninth intermediate shaft front end, the ninth intermediate shaft rear end, the ninth differential shaft front end, and the ninth differential shaft rear end are all less than the allowable shaft voltage value: based on the voltages of the tenth input shaft front end, the tenth input shaft rear end, the tenth intermediate shaft front end, the tenth intermediate shaft rear end, the tenth differential shaft front end, and the tenth differential shaft rear end, collected by the mode ten test method. If all of these voltages are less than the allowable shaft voltage value, the module formulates a countermeasure to add grounding rings at both ends of the motor; otherwise, it formulates a countermeasure to add an insulating coating at the bearings in the electric drive assembly that are not less than the allowable shaft voltage value.

12. The electric drive assembly shaft voltage testing system as described in claim 11, characterized in that: The judgment module also includes, The eleventh countermeasure formulation module is used to test according to mode seven and mode one when the bearings of the current electric drive assembly have the risk of electrical corrosion on the motor side and the risk of electrical corrosion on the gearbox side. If the shaft voltage of all bearing positions in the electric drive assembly measured by mode seven and mode one is less than the allowable value of shaft voltage, then no countermeasures need to be taken; otherwise, the test is carried out according to mode eight and mode four. If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 8 and Mode 4 are less than the allowable shaft voltage, then the solution of installing a grounding ring at the front end of the motor should be adopted to reduce the shaft voltage; otherwise, the test should be performed according to Mode 9 and Mode 5. If the shaft voltages of all bearing positions in the electric drive assembly measured in Modes 9 and 5 are less than the allowable shaft voltage, then a solution of installing a grounding ring at the rear end of the motor should be adopted to reduce the shaft voltage; otherwise, tests should be conducted according to Modes 10 and 6. If the shaft voltages of all bearing positions in the electric drive assembly measured in Mode 10 and Mode 6 are less than the allowable shaft voltage, then a solution of installing grounding rings at both the front and rear ends of the motor is adopted to reduce the shaft voltage. If the bearing shaft voltage is consistently not less than the allowable shaft voltage value in all four modes, then a countermeasure will be formulated to replace the motor bearing in the electric drive assembly with a ceramic ball bearing or to use an insulating coating to insulate the bearing from the housing and shaft in contact with it, and a countermeasure will be formulated to replace the gearbox bearing in the electric drive assembly with a ceramic ball bearing.

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