Electric drive assembly shaft voltage test method and test system

Abstract

The invention relates to the technical field of electric drive assembly testing, in particular to an electric drive assembly shaft voltage testing method and system. Comprising the following steps: arranging a grounding point on an electric drive assembly, and arranging a first measuring point and a second measuring point at two axial ends of a motor shaft; controlling the on-off of eleven grounding points to realize different test modes, dragging the electric drive assembly to operate by using the rack, and recording the voltage of the first test point and the second test point in each test mode; and analyzing the recorded voltages of the first test point and the second test point in each test mode, and judging whether a corresponding countermeasure needs to be made for the electric drive assembly or not. The electric drive assembly shaft voltage testing method is simple, whether the electric drive assembly bearing has the electrocorrosion risk or not can be accurately obtained, the testing item is extremely blocked, the corresponding countermeasure can be made according to the corresponding risk, the change corresponding to the countermeasure is extremely small, and the cost is extremely low.

Description

Technical Field

[0001] The present invention relates to the technical field of electric drive assembly testing, and in particular to an electric drive assembly shaft voltage testing method and testing system. Background Art

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

[0003] The cause of bearing electrical corrosion is that when the shaft voltage breaks through the bearing raceway oil film between the inner and outer rings of the bearing, the energy generated causes corrosion of the raceways and steel balls. The shaft voltage amplitude is positively correlated with the controller input voltage, which is why the electrical corrosion of the 800V electric drive assembly is more serious than that of the 400V assembly. The impact of the shaft voltage on the entire electric drive assembly system is related to many aspects such as the controller control logic, bearing type, lubricating oil characteristics, grounding ring effect, and reduction gear shaft teeth. It is a problem with many influencing factors. How to systematically measure the shaft voltage amplitude, shaft current amplitude, and shaft voltage release path of the entire electric drive assembly will help to adopt the most economical and appropriate solution to improve bearing electrical corrosion during the design and development process.

[0004] Regardless of whether it is an oil-cooled or water-cooled electric drive assembly, the kinematic viscosity coefficient of lubricating oil and grease is greatly affected by temperature and decreases exponentially as the temperature rises. Therefore, during the operation of the electric drive assembly, a stable oil film is often unable to form at the bearing, which has a great impact on the test results. Therefore, the shaft voltage test often requires various modifications to obtain shaft voltage data that is easy to analyze. Common shaft voltage tests and modification methods are:

[0005] 1. Three-in-one assembly test: Use the three-in-one assembly composed of motor + electronic control + reduction box to measure the shaft voltage at the bearing position;

[0006] 2. Two-in-one assembly test: without the reduction 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 bearings with ceramic ball bearings and test the shaft voltage at the bearing position.

[0008] The shaft voltage test often requires multiple rounds of modification and testing to obtain the required results. For example, after completing the initial state assembly test, the assembly needs to be disassembled, the grounding ring needs to be installed, and then the shaft voltage change needs to be measured; or the metal bearing needs to be replaced with a ceramic ball bearing, and the shaft voltage change needs to be measured again. If the analysis and solution of the electrical corrosion problem of the gearbox side bearing is involved, the situation will be more complicated. Each round of modification of the electric drive assembly takes several days, which is not only time-consuming and costly, but also the modification of the assembly will affect or even destroy the assembly state, resulting in differences in test results. Summary of the invention

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

[0010] The technical solution of the present application is: a method for testing the 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 both ends of the bearings of the input shaft assembly, a fifth grounding point and a sixth grounding point located at both ends of the bearings of the intermediate shaft assembly, a seventh grounding point and an eighth grounding point located at both ends of the bearings of the differential assembly, a ninth grounding point and a tenth grounding point located at both ends of the bearings of the motor shaft, and an eleventh grounding point located at the main housing of the electric drive assembly;

[0012] Arrange a first measuring point and a second measuring point at both ends of the motor shaft;

[0013] Control the on and off of eleven grounding points to achieve different test modes, use the test bench to drag the electric drive assembly to run, and record the voltage of the first and second test points in each test mode;

[0014] The voltages of the first and second measuring points recorded in each test mode are analyzed to determine whether corresponding countermeasures need to be formulated for the electric drive assembly.

[0015] According to a method for testing the shaft voltage of an electric drive assembly provided in the present application, the method for arranging grounding points on the electric drive assembly includes: arranging a lead wire on each grounding point, one end of the lead wire enters the insulating base at the grounding point through the main shell and is connected to the corresponding grounding point, and the other end is connected to the grounding wire, and a switch is arranged on the lead wire.

[0016] According to a method for testing shaft voltage of an electric drive assembly provided by the present application, the method for controlling the on and off of eleven grounding points to realize different test modes includes:

[0017] Mode 1: disconnect the first grounding point and the second grounding point, connect the remaining grounding points, use the test bench to drag 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 of the first motor and the rear end voltage of the first motor;

[0018] Mode 2: Connect the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnect the remaining grounding points, use the test bench to drag 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 of the second motor and the rear end voltage of the second motor;

[0019] Mode three, disconnect the first grounding point, the second grounding point, the ninth grounding point and the tenth grounding point, connect the remaining grounding points, use the test bench to drag 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 of the third motor and the rear end voltage of the third motor.

[0020] According to a method for testing shaft voltage of an electric drive assembly provided by the present application, the method for analyzing the recorded shaft voltage of the front end of the motor and the shaft voltage of the rear end of the motor 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 judged that the risk of electrical corrosion of the bearing 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 judged that the bearing of the current electric drive assembly has the risk of motor-side electrical corrosion, and it is necessary to further judge and make corresponding countermeasures based on the voltage;

[0022] If the waveforms of the second motor front-end voltage and the second motor rear-end voltage are common-mode waveforms, and the waveforms of the first motor front-end voltage, the first motor rear-end voltage, the third motor front-end voltage, and the third motor rear-end voltage are breakdown waveforms, it is determined that the bearing of the current electric drive assembly has a risk of electrical corrosion on the reduction gearbox side, and further judgment and corresponding countermeasures need to be made based on the voltage;

[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 judged that the bearings of the current electric drive assembly have the risk of electrical corrosion on the reduction gearbox side and the motor side, and further judgment and corresponding countermeasures need to be made based on the voltage.

[0024] According to an electric drive assembly shaft voltage testing method provided in the present application, when judging whether the bearings of the current electric drive assembly have the risk of electric corrosion on the motor side and / or the risk of electric corrosion on the reduction gearbox side, if 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 all less than the allowable value of the shaft voltage, then it is judged that the current risk of electric corrosion of the bearing is low and no countermeasures are needed; otherwise, it is necessary to further judge and make corresponding countermeasures based on the voltage.

[0025] According to a method for testing shaft voltage of an electric drive assembly provided by the present application, when it is determined that the bearing of the current electric drive assembly has a risk of electric corrosion on the motor side, if 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 do not satisfy the condition that they are all less than the allowable value of the shaft voltage, a test of mode four is performed; the testing method of mode four is: connecting the first grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnecting the remaining grounding points, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the fourth motor and the rear end voltage of the fourth motor;

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

[0027] The test method of mode five is: connecting the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnecting the remaining grounding points, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the fifth motor and the rear end voltage of the fifth motor;

[0028] If the voltage at the front end of the fifth motor and the voltage at the rear end of the fifth motor are both 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 six is ​​carried out;

[0029] The test method of mode six is: connecting the first grounding point, the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnecting the remaining grounding points, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the sixth motor and the rear end voltage of the sixth motor;

[0030] If the front end voltage of the sixth motor and the rear end voltage of the sixth motor are both lower than the allowable value of the shaft voltage, the electric drive assembly adopts the countermeasure of adding grounding rings at the front and rear ends of the motor. Otherwise, the bearings of the electric drive assembly are replaced with ceramic ball bearings or insulating coatings are used to insulate the bearings from the housing and shaft in contact with them.

[0031] According to a method for testing the shaft voltage of an electric drive assembly provided by the present application, when it is determined that the bearing of the current electric drive assembly has a risk of electrical corrosion on the reduction gearbox side, if 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 do not satisfy the situation that they are all less than the allowable value of the shaft voltage, a mode seven test is performed; the test method of mode seven is: connecting the first measuring point and the two sides of the switch corresponding to the third grounding point, connecting the second measuring point and the two sides of the switch corresponding to the fourth grounding point, disconnecting the first grounding point, the second grounding point, the third grounding point and the fourth grounding point, connecting the remaining grounding points, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the seventh input shaft front end voltage and the seventh input The voltage at the rear end of the input shaft; connect the first measuring point to both sides of the switch corresponding to the fifth grounding point, connect the second measuring point to both sides of the switch corresponding to the sixth location, disconnect the first grounding point, the second grounding point, the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the test bench to drag 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 of the seventh intermediate shaft and the rear end voltage of the seventh intermediate shaft; connect the first measuring point to both sides of the switch corresponding to the seventh grounding point, connect the second measuring point to both sides of the switch corresponding to the eighth location, disconnect the first grounding point, the second grounding point, the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the test bench to drag 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 of the seventh differential shaft 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, it is judged that the risk of electrical corrosion of the bearings at both ends of the axial direction of the current electric drive assembly input shaft component is low, and no countermeasures are required; otherwise, the test of mode eight is performed;

[0033] The test method of the mode eight is as follows: connect the first measuring point with both sides of the switch corresponding to the third grounding point, connect the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnect the second grounding point, the third grounding point and the fourth grounding point, connect the remaining grounding points, use the 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 of the eighth input shaft and the rear end voltage of the eighth input shaft; connect the first measuring point with both sides of the switch corresponding to the fifth grounding point, connect the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnect the second grounding point, the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the 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 of the eighth intermediate shaft and the rear end voltage of the eighth intermediate shaft; connect the first measuring point with both sides of the switch corresponding to the seventh grounding point, connect the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnect the second grounding point, the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the 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 of the eighth differential shaft and the rear end voltage 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 adopts the countermeasure of adding a grounding ring at the front end of the motor, otherwise, the test of mode nine is carried out;

[0035] The test method of mode nine is as follows: connect the first measuring point with both sides of the switch corresponding to the third grounding point, connect the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnect the first grounding point, the third grounding point and the fourth grounding point, connect the remaining grounding points, use the 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 of the ninth input shaft and the rear end voltage of the ninth input shaft; connect the first measuring point with both sides of the switch corresponding to the fifth grounding point, connect the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnect the first grounding point, the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the 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 of the ninth intermediate shaft and the rear end voltage of the ninth intermediate shaft; connect the first measuring point with both sides of the switch corresponding to the seventh grounding point, connect the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnect the first grounding point, the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the 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 of the ninth differential shaft and the rear end voltage 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 10 is performed;

[0037] The test method of the mode ten is as follows: connect the first measuring point with both sides of the switch corresponding to the third grounding point, connect the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnect the third grounding point and the fourth grounding point, connect the remaining grounding points, use the 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 of the tenth input shaft and the rear end voltage of the tenth input shaft; connect the first measuring point with both sides of the switch corresponding to the fifth grounding point, connect the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnect the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the 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 of the tenth intermediate shaft and the rear end voltage of the tenth intermediate shaft; connect the first measuring point with both sides of the switch corresponding to the seventh grounding point, connect the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnect the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the 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 of the tenth differential shaft and the rear end voltage of the tenth differential shaft;

[0038] If the front end voltage of the tenth input shaft, the rear end voltage of the tenth input shaft, the front end voltage of the tenth intermediate shaft, the rear end voltage of the tenth intermediate shaft, the front end voltage of the tenth differential shaft, and the rear end voltage of the tenth differential shaft are all lower than the allowable value of the shaft voltage, the electric drive assembly shall adopt the countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, the countermeasure of adding insulating coating to the bearings in the reduction gearbox with a value not lower than the allowable value of the shaft voltage shall be adopted.

[0039] According to a method for testing shaft voltage of an electric drive assembly provided by the present application, when it is determined that the bearings of the current electric drive assembly have the risk of electric corrosion on the motor side and the risk of electric corrosion on the reduction gearbox side, the test is performed according to mode seven and mode one. If the shaft voltages of all bearings in the electric drive assembly measured in mode seven and mode one are less than the allowable value of the shaft voltage, no countermeasures are required; otherwise, the test is performed according to mode eight and mode four.

[0040] If the shaft voltages of all bearings in the electric drive assembly measured in mode eight and mode four are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the front end of the motor; otherwise, test according to mode nine and mode five;

[0041] If the shaft voltages of all bearings in the electric drive assembly measured in mode nine and mode five are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the rear end of the motor; otherwise, test according to mode ten and mode six;

[0042] If the shaft voltages of all bearings in the electric drive assembly measured in mode 10 and mode 6 are less than the allowable shaft voltage value, the shaft voltage can be reduced by installing grounding rings at both the front and rear ends of the motor;

[0043] If the shaft voltage of a bearing is always not less than the allowable shaft voltage value in the four modes, the motor bearing is replaced with a ceramic ball bearing or an insulating coating is used to insulate the bearing from the housing and shaft in contact with it, or the reduction gearbox bearing is replaced with a ceramic ball bearing.

[0044] The present application also provides an electric drive assembly shaft voltage test system, the test system is operated according to any of the above-mentioned electric drive assembly shaft voltage test methods, including:

[0045] A grounding point module, the grounding point 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 both ends of the bearings of the input shaft assembly, a fifth grounding point and a sixth grounding point located at both ends of the bearings of the intermediate shaft assembly, a seventh grounding point and an eighth grounding point located at both ends of the bearings of the differential assembly, a ninth grounding point and a tenth grounding point located at both ends of the bearings of the motor shaft, and an eleventh grounding point located at the main housing of the electric drive assembly;

[0046] A measuring point module, the measuring point module comprising a first measuring point and a second measuring point located at two axial ends of the motor shaft;

[0047] A test module, wherein the test module realizes different test modes by controlling the on and off of eleven grounding points, and records the voltage of the first test point and the second test point in each test mode;

[0048] A judgment module is used to analyze and judge whether it is necessary to formulate corresponding countermeasures for the electric drive assembly based on the voltage of the first measurement point and the second measurement point in each test mode.

[0049] According to an electric drive assembly shaft voltage testing system provided by the present application, the testing module includes:

[0050] A first module, wherein the first module implements a mode one 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 measuring point and the second measuring point under the mode one test method as a first motor front end voltage and a first motor rear end voltage;

[0051] The second module implements the mode 2 test method by connecting 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 measuring point and the second measuring point 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] A third module, wherein the third module implements a 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 measuring point and the second measuring point under the mode three test method as a front end voltage of the third motor and a rear end voltage of the third motor;

[0053] A fourth module, wherein the fourth module implements a mode four 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 measuring point and the second measuring point under the mode four test method as a front end voltage of the fourth motor and a rear end voltage of the fourth motor;

[0054] A fifth module, wherein the fifth module implements a 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 measuring point and the second measuring point under the mode five test method as a front end voltage of the fifth motor and a rear end voltage of the fifth motor;

[0055] A sixth module, wherein the sixth module implements a mode six 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 measuring point and the second measuring point under the mode six test method as a front end voltage of the sixth motor and a rear end voltage of the sixth motor;

[0056] The seventh module implements the mode seven test method by connecting the first measuring point with both sides of the switch corresponding to the third grounding point, connecting the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnecting the first grounding point, the second grounding point, the third grounding point and the fourth grounding point, and connecting the remaining grounding points, and recording the voltages of the first measuring point and the second measuring point under the mode seven test method as the front end voltage of the seventh input shaft and the rear end voltage of the seventh input shaft; connecting the first measuring point with both sides of the switch corresponding to the fifth grounding point, connecting the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnecting the first grounding point and the second grounding point, and connecting the second grounding point and the sixth grounding point. , the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the test bench to drive the electric drive assembly to run, record the voltages of the first measuring point and the second measuring point as the front end voltage of the seventh intermediate shaft and the rear end voltage of the seventh intermediate shaft; connect the first measuring point with both sides of the switch corresponding to the seventh grounding point, connect the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnect the first grounding point, the second grounding point, the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the test bench to drive the electric drive assembly to run, record the voltages of the first measuring point and the second measuring point as the front end voltage of the seventh differential shaft and the rear end voltage of the seventh differential shaft;

[0057] The eighth module implements the mode eight test method by connecting the first measuring point with both sides of the switch corresponding to the third grounding point, connecting the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnecting the second grounding point, the third grounding point and the fourth grounding point, and connecting the remaining grounding points, and records the voltages of the first measuring point and the second measuring point under the mode eight test method as the front end voltage of the eighth input shaft and the rear end voltage of the eighth input shaft; connecting the first measuring point with both sides of the switch corresponding to the fifth grounding point, connecting the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnecting the second grounding point, the fifth grounding point and the sixth grounding point, connecting the remaining grounding points, using the test bench to drive the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the eighth intermediate shaft and the rear end voltage of the eighth intermediate shaft; connecting the first measuring point with both sides of the switch corresponding to the seventh grounding point, connecting the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnecting the second grounding point, the seventh grounding point and the eighth grounding point, connecting the remaining grounding points, using the test bench to drive the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the eighth differential shaft and the rear end voltage of the eighth differential shaft;

[0058] The ninth module implements the mode nine test method by connecting the first measuring point to both sides of the switch corresponding to the third grounding point, connecting the second measuring point to both sides of the switch corresponding to the fourth grounding point, disconnecting the first grounding point, the third grounding point and the fourth grounding point, and connecting the remaining grounding points, and records the voltages of the first measuring point and the second measuring point under the mode nine test method as the front end voltage of the ninth input shaft and the rear end voltage of the ninth input shaft; connecting the first measuring point to both sides of the switch corresponding to the fifth grounding point, connecting the second measuring point to both sides of the switch corresponding to the sixth grounding point, disconnecting the first grounding point, the fifth grounding point and the sixth grounding point, connecting the remaining grounding points, using the test bench to drive the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the ninth intermediate shaft and the rear end voltage of the ninth intermediate shaft; connecting the first measuring point to both sides of the switch corresponding to the seventh grounding point, connecting the second measuring point to both sides of the switch corresponding to the eighth grounding point, disconnecting the first grounding point, the seventh grounding point and the eighth grounding point, connecting the remaining grounding points, using the test bench to drive the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the ninth differential shaft and the rear end voltage of the ninth differential shaft;

[0059] The tenth module implements the mode ten test method by connecting the first measuring point to both sides of the switch corresponding to the third grounding point, connecting the second measuring point to both sides of the switch corresponding to the fourth location, disconnecting the third grounding point and the fourth grounding point, and connecting the remaining grounding points, and records the voltages of the first measuring point and the second measuring point under the mode ten test method as the front end voltage of the tenth input shaft and the rear end voltage of the tenth input shaft; connects the first measuring point to both sides of the switch corresponding to the fifth grounding point, connects the second measuring point to both sides of the switch corresponding to the sixth location, disconnects the fifth grounding point and the sixth grounding point, connects the remaining grounding points, uses a test bench to drive the electric drive assembly to run, and records the voltages of the first measuring point and the second measuring point as the front end voltage of the tenth intermediate shaft and the rear end voltage of the tenth intermediate shaft; connects the first measuring point to both sides of the switch corresponding to the seventh grounding point, connects the second measuring point to both sides of the switch corresponding to the eighth location, disconnects the seventh grounding point and the eighth grounding point, connects the remaining grounding points, uses a test bench to drive the electric drive assembly to run, and records the voltages of the first measuring point and the second measuring point as the front end voltage of the tenth differential shaft and the rear end voltage of the tenth differential shaft.

[0060] According to an electric drive assembly shaft voltage testing system provided by the present application, the judgment module includes:

[0061] a corrosion-free risk judgment module, wherein the corrosion-free risk judgment module judges that the risk of electrical corrosion of the bearing of the current electric drive assembly is low and no countermeasures need to be formulated when 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;

[0062] A motor-side corrosion-free risk judgment module, wherein 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, the motor-side corrosion-free risk judgment module makes a judgment that the bearing of the current electric drive assembly has a motor-side electrical corrosion risk and needs to be further judged in combination with the voltage and corresponding countermeasures are taken;

[0063] A reduction gearbox side corrosion risk judgment module, wherein when the waveforms of the second motor front end voltage and the second motor rear end voltage are common mode waveforms, and the waveforms of the first motor front end voltage, the first motor rear end voltage, the third motor front end voltage and the third motor rear end voltage are breakdown waveforms, the reduction gearbox side corrosion risk judgment module makes a judgment that the bearing of the current electric drive assembly has a reduction gearbox side electrical corrosion risk and needs to be further judged in combination with the voltage and corresponding countermeasures are taken;

[0064] A corrosion risk judgment module on both sides, when 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, makes a judgment that the bearings of the current electric drive assembly have electrical corrosion risks on the reduction gearbox side and the motor side, and further judgment and corresponding countermeasures need to be made based on the voltage.

[0065] According to an electric drive assembly shaft voltage testing system provided by the present application, the judgment module further includes:

[0066] A no-countermeasure formulation module, wherein the no-countermeasure formulation module is used to make a judgment that the current bearing electrical corrosion risk is low and no countermeasures are required when it is judged that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side and / or a risk of electrical corrosion on the reduction gearbox side, and 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 less than the allowable value of the shaft voltage;

[0067] A fourth countermeasure formulation module, wherein the fourth countermeasure formulation module is used to make further judgments based on the fourth motor front end voltage and the fourth motor rear end voltage collected by the mode four test method when it is judged that the bearing of the current electric drive assembly has a risk of electric corrosion on the motor side and 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 not all less than the allowable value of the shaft voltage, and when the fourth motor front end voltage and the fourth motor rear end voltage are both less than the allowable value of the shaft voltage, formulate a countermeasure of adding a grounding ring to the front end of the motor;

[0068] A fifth countermeasure formulation module, wherein the fifth countermeasure formulation module is used to make further judgments based on the fifth motor front end voltage and the fifth motor rear end voltage collected by the mode five test method when the fourth motor front end voltage and the fourth motor rear end voltage are both less than the shaft voltage allowable value, and formulate a countermeasure of adding a grounding ring at the rear end of the motor when the fifth motor front end voltage and the fifth motor rear end voltage are both less than the shaft voltage allowable value;

[0069] The sixth countermeasure formulation module is used to make further judgments based on the front-end voltage of the sixth motor and the rear-end voltage of the sixth motor collected by the mode six test method when the situation that the front-end voltage of the fifth motor and the rear-end voltage of the fifth motor are both less than the allowable value of the shaft voltage is not satisfied, and to formulate a countermeasure of adding grounding rings at the front and rear ends of the motor when the front-end voltage of the sixth motor and the rear-end voltage of the sixth motor are both less than the allowable value of the shaft voltage, otherwise, a countermeasure of replacing the bearings of the electric drive assembly with ceramic ball bearings or using insulating coatings to insulate the bearings from the housing and shaft in contact with them is formulated.

[0070] According to an electric drive assembly shaft voltage testing system provided by the present application, the judgment module further includes:

[0071] A seventh countermeasure formulation module, wherein the seventh countermeasure formulation module is used to make further judgments based on the seventh input shaft front end voltage, the seventh input shaft rear end voltage, the seventh intermediate shaft front end voltage, the seventh intermediate shaft rear end voltage, the seventh differential shaft front end voltage, and the seventh differential shaft rear end voltage collected by the mode seven test method when it is judged that the bearing of the current electric drive assembly has a risk of electrical corrosion on the reduction gearbox side and 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 not all less than the allowable value of the shaft voltage, and when the front end voltage of the seventh input shaft, the rear end voltage of the seventh input shaft, the front end voltage of the seventh intermediate shaft, the rear end voltage of the seventh intermediate shaft, the front end voltage of the seventh differential shaft, and the rear end voltage of the seventh differential shaft are all less than the allowable value of the shaft voltage, make a judgment that there is no need to formulate countermeasures for the reduction gearbox bearing of the electric drive assembly;

[0072] an eighth countermeasure formulation module, wherein the eighth countermeasure formulation module is used for making further judgments based on the eighth input shaft front end voltage, the eighth input shaft rear end voltage, the eighth intermediate shaft front end voltage, the eighth intermediate shaft rear end voltage, the eighth differential shaft front end voltage, and the eighth differential shaft rear end voltage collected by the mode eight test method when the seventh input shaft front end voltage, the seventh input shaft rear end voltage, the seventh intermediate shaft front end voltage, the seventh intermediate shaft rear end voltage, the seventh differential shaft front end voltage, and the eighth differential shaft rear end voltage are all less than the shaft voltage allowable value, and when the eighth input shaft front end voltage, the eighth input shaft rear end voltage, the eighth intermediate shaft front end voltage, the eighth intermediate shaft rear end voltage, the eighth differential shaft front end voltage, and the eighth differential shaft rear end voltage are all less than the shaft voltage allowable value, formulating a countermeasure of adding a grounding ring to the front end of the motor;

[0073] a ninth countermeasure formulation module, wherein the ninth countermeasure formulation module is used for making further judgments based on the ninth input shaft front end voltage, the ninth input shaft rear end voltage, the ninth intermediate shaft front end voltage, the ninth intermediate shaft rear end voltage, the ninth differential shaft front end voltage, and the ninth differential shaft rear end voltage collected by the mode nine test method when the eighth input shaft front end voltage, the eighth input shaft rear end voltage, the eighth intermediate shaft front end voltage, the eighth intermediate shaft rear end voltage, the eighth differential shaft front end voltage, and the ninth differential shaft rear end voltage are all less than the shaft voltage allowable value, and when the ninth input shaft front end voltage, the ninth input shaft rear end voltage, the ninth intermediate shaft front end voltage, the ninth intermediate shaft rear end voltage, the ninth differential shaft front end voltage, and the ninth differential shaft rear end voltage are all less than the shaft voltage allowable value, formulating a countermeasure of adding a grounding ring at the rear end of the motor;

[0074] The tenth countermeasure formulation module is used for making further judgments based on the tenth input shaft front end voltage, the tenth input shaft rear end voltage, the tenth intermediate shaft front end voltage, the tenth intermediate shaft rear end voltage, the tenth differential shaft front end voltage, and the tenth differential shaft rear end voltage collected by the mode ten test method when the situation that the ninth input shaft front end voltage and the ninth input shaft rear end voltage, the ninth intermediate shaft front end voltage, the ninth intermediate shaft rear end voltage, the ninth differential shaft front end voltage, and the ninth differential shaft rear end voltage are all less than the allowable shaft voltage. When the tenth input shaft front end voltage, the tenth input shaft rear end voltage, the tenth intermediate shaft front end voltage, the tenth intermediate shaft rear end voltage, the tenth differential shaft front end voltage, and the tenth differential shaft rear end voltage are all less than the allowable shaft voltage, a countermeasure of adding grounding rings at the front and rear ends of the motor is formulated; otherwise, a countermeasure of adding insulating coatings at bearings in the electric drive assembly that are not less than the allowable shaft voltage value is formulated.

[0075] According to an electric drive assembly shaft voltage testing system provided by the present application, the judgment module further includes:

[0076] The eleventh countermeasure formulation module is used for testing according to mode seven and mode one when the bearings of the current electric drive assembly have the risk of electric corrosion on the motor side and the risk of electric corrosion on the reduction gearbox side. If the shaft voltages of all bearings in the electric drive assembly measured by mode seven and mode one are less than the allowable value of the shaft voltage, no countermeasures are required; otherwise, the test is performed according to mode eight and mode four;

[0077] If the shaft voltages of all bearings in the electric drive assembly measured in mode eight and mode four are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the front end of the motor; otherwise, test according to mode nine and mode five;

[0078] If the shaft voltages of all bearings in the electric drive assembly measured in mode nine and mode five are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the rear end of the motor; otherwise, test according to mode ten and mode six;

[0079] If the shaft voltages of all bearings in the electric drive assembly measured in mode 10 and mode 6 are less than the allowable shaft voltage value, the shaft voltage can be reduced by installing grounding rings at both the front and rear ends of the motor;

[0080] If the shaft voltage of a bearing is always not less than the allowable shaft voltage value in the four modes, a countermeasure is formulated to replace the motor bearing with a ceramic ball bearing or use an insulating coating to insulate the bearing from the housing and shaft in contact with it, and a countermeasure is formulated to replace the reduction box bearing with a ceramic ball bearing.

[0081] The advantages of the present application are as follows: 1. By setting multiple grounding points and multiple measuring points on the electric drive assembly, the present application can control the on and off of the grounding points to achieve the measurement of shaft voltage in different modes. The shaft voltage in various modes can be obtained without disassembling the electric drive assembly. Not only the common mode voltage but also the breakdown voltage can be evaluated. The test items are rich, the test efficiency is extremely high, and the test time is short. Different countermeasures can also be formulated for different electrical corrosion risks. The formulated countermeasures are also feasible, the required changes are extremely small, the cost is extremely low, and it has great promotion value.

[0082] 2. The main housing of the electric drive assembly of the present application is provided with an insulating base, and the shaft voltage release path is changed from the traditional mode of rotating shaft-bearing-housing-ground wire to rotating shaft-bearing-lead wire-switch-ground wire through lead wires and switches. By turning the switch on and off, the shaft voltage release path can be controlled in real time. The grounding point control operation is very simple, and when the grounding point is grounded, it can represent the state of adding a grounding ring to solve the countermeasures here. It is convenient to formulate whether a grounding ring can be added here to solve the risk of electrical 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 states of the electric drive assembly, the electric drive assembly is in the state of insulation on the reduction gearbox side, the motor bearing and the housing are connected, and the electric drive assembly is in the state of insulation on the motor side, the reduction gearbox bearing and the housing are connected. Through the test of the three modes, the specific situation of the current electric drive assembly's electrical corrosion risk can be accurately judged, which is convenient for the subsequent formulation of corresponding countermeasures;

[0084] 4. The present application has a very simple method for determining whether there is an electrical corrosion risk. By using an oscilloscope to analyze 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, it is not only possible to analyze the common mode waveform, but also the breakdown waveform. The analysis content is richer, the analysis result is more accurate, and the location of the electrical corrosion risk of the current electric drive assembly can be determined more accurately.

[0085] 5. In the case of a preliminary judgment that there is a risk of electrical corrosion, the present application further judges 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 to avoid misjudgment and further judge whether countermeasures need to be taken, thereby improving the accuracy of the judgment and facilitating the subsequent formulation of corresponding countermeasures;

[0086] 6. This application further judges the situation where the motor side bearing has the risk of electrical corrosion. Through the judgment and analysis of the test methods of mode 4, mode 5 and mode 6, it can accurately obtain the countermeasures when the motor side bearing has the risk of electrical corrosion. It can formulate corresponding countermeasures for different situations, and the formulated measures can accurately solve the risk of electrical corrosion on the motor side;

[0087] 7. This application further judges the situation where there is a risk of electrical corrosion on the bearing on the gearbox side. Through the judgment and analysis of the test methods of mode seven, mode eight, mode nine and mode ten, it is possible to accurately obtain the countermeasures when there is a risk of electrical corrosion on the bearing on the gearbox side. Corresponding countermeasures can be formulated for different situations. The formulated measures can accurately solve the risk of electrical corrosion on the gearbox side.

[0088] 8. When the bearings of the current electric drive assembly have the risk of electric corrosion on the motor side and the risk of electric corrosion on the reduction gearbox side, the shaft voltages of all bearings are collected through the 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 is determined whether there is a problem with the bearing. If there is a problem, a corresponding countermeasure can be formulated. It is more targeted and can quickly find the position of the bearing with the risk of electric corrosion and quickly formulate a corresponding countermeasure.

[0089] 9. The present application also provides an electric drive assembly shaft voltage testing system. The testing system of the present application can be integrated into a control system to form an automatic testing and countermeasure output system, thereby facilitating the testing of the electric drive assembly and further improving the testing efficiency.

[0090] The electric drive assembly shaft voltage test method of the present application is simple and can accurately determine whether there is a risk of electrical corrosion in the electric drive assembly bearing. The test items are extremely closed and corresponding countermeasures can be formulated according to the corresponding risks. The corresponding changes to the countermeasures are extremely small and the cost is extremely low, which has great promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 : Schematic diagram of the arrangement of grounding points and measuring points of the electric drive assembly of the present application;

[0092] Figure 2 : Schematic diagram of the electric drive assembly shaft voltage test structure of the present application;

[0093] Among them: 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; 32—E bearing; 33—insulating base. DETAILED DESCRIPTION

[0094] The embodiments of the present application are described in detail below, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0095] In the description of the present application, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0096] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0097] The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0098] The present application relates to a method for testing the shaft voltage of an electric drive assembly. The present application sets a grounding point and a measuring point on the electric drive assembly, and realizes different states of the electric drive assembly by controlling the on and off of the grounding point. When the grounding point is grounded, it can simulate the state of installing a grounding ring here, so as to facilitate the formulation of corresponding countermeasures to solve the risk of electrical corrosion. The entire test method is simple and easy to operate, and the present application can not only analyze the common mode waveform, but also analyze the breakdown waveform. The content of the analysis is richer, the analysis results are more accurate, and it can more accurately determine the location of the current electric drive assembly where the risk of electrical corrosion occurs.

[0099] Specifically, Figures 1-2 As shown, a method for testing shaft voltage of an electric drive assembly of the present application comprises the following steps:

[0100] S1. Arrange grounding points 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 both ends of the bearings of the input shaft 26 assembly, a fifth grounding point 5 and a sixth grounding point 6 located at both ends of the bearings of the intermediate shaft 29 assembly, a seventh grounding point 7 and an eighth grounding point located at both ends of the bearings of the differential 31 assembly, a ninth grounding point 9 and a tenth grounding point 10 located at both ends of the bearings of the motor shaft, and an eleventh grounding point 11 located at the main housing 15 of the electric drive assembly;

[0101] The purpose of arranging the grounding point on the electric drive assembly is to lead out the position of the bearing involved in the electric drive assembly, so as to facilitate the subsequent grounding of the bearing position and simulate the effect of installing a grounding ring at this position; the electric drive assembly of the present 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 in the electric drive assembly are: the bearings at both ends of the motor shaft, namely the M bearing 21 and the N bearing 20 at the front end of the motor shaft; the bearings at both ends of the input shaft 26, namely the B bearing 25 at the front end of the input shaft 26 and the A bearing 24 at the rear end of the input shaft 26; the bearings at both ends of the intermediate shaft 29, namely the D bearing at the front end of the intermediate shaft 29 and the C bearing at the rear end of the intermediate shaft 29; the bearings at both ends of the differential 31 axial direction, respectively. 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; grounding points are arranged on the A bearing 24, the B bearing 25, the C bearing, the D bearing, the E bearing 32, the F bearing 30, the M bearing 21 and the N bearing 20 respectively; the M bearing 21 corresponds to the ninth grounding point 9, the N bearing 20 corresponds to the tenth grounding point 10, the A bearing 24 corresponds to the third grounding point 3, the B bearing 25 corresponds to the fourth grounding point 4, the D bearing corresponds to the fifth grounding point 5, the C bearing corresponds to the sixth grounding point 6, the F bearing 30 corresponds to the seventh grounding point 7, and the E bearing 32 corresponds to the eighth grounding point 8; in addition, there are grounding points at both ends of the motor shaft, which are 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 arrangement of the grounding points is to arrange a lead wire at each grounding point, and one end of the lead wire enters the insulating base 33 at the grounding point through the main housing 15 (such as Figure 2 The insulating base 33 is shown in the schematic diagram of the arrangement of the insulating base 33, which is connected to the corresponding grounding point, and the other end is connected to the grounding wire. A switch is arranged on the lead-out wire, and the purpose of controlling the on and off of the grounding point can be achieved by opening and closing the switch. The grounding point is connected, which means that the switch is closed, and the electric drive assembly part corresponding to the grounding point is grounded. The grounding point is disconnected, which means that the switch is disconnected, and the electric drive assembly part corresponding to the grounding point is not grounded;

[0103] S2, arranging a first measuring point 13 and a second measuring point 14 at both ends of the motor shaft;

[0104] Measuring the shaft voltage of the electric drive assembly is actually measuring the voltage at both 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 (such as Figure 2 As shown, the first measuring point 13 includes a first axis voltage measuring point 22 and a first axis voltage grounding point 23) and a second measuring point 14 at the second grounding point 2 (as shown in FIG. Figure 2 As shown, the second measuring point 14 includes a second axis voltage measuring point 18 and a second axis voltage grounding point 19);

[0105] All grounding points and measuring points are connected to the oscilloscope (such as Figure 1 The oscilloscope ground wire 12 shown is connected, the data collected by the measuring point is transmitted to the oscilloscope, and the judgment and analysis are performed according to the waveform of the voltage collected on the oscilloscope;

[0106] S3, controlling the on and off of eleven grounding points to realize different test modes, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point 13 and the second measuring point 14 in each test mode, which are the motor front end shaft voltage and the motor rear end shaft voltage respectively;

[0107] The on-off control of the grounding points is achieved by controlling the switches on the eleven grounding points. The on-off control of the grounding points at different positions corresponds to different working modes of the electric drive assembly. By controlling the on-off control of the switches, the tests in different modes can be realized.

[0108] The electric drive assembly of the present application is mounted on a bench for simulation experiments;

[0109] S4. Analyze the recorded motor front end shaft voltage and motor rear end shaft voltage to determine whether it is necessary to formulate corresponding countermeasures for the electric drive assembly.

[0110] In some embodiments of the present application, this embodiment optimizes the above step S3. Specifically, the method of controlling the on and off of eleven grounding points to realize different test modes in this embodiment is as follows: In this embodiment, 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, use the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the first motor front end voltage U f1 and the first motor rear end voltage U 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, use the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the second motor front end voltage U f2 and the second motor rear end voltage U r2 ;

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

[0114] The three modes of the preliminary test correspond to three different states of the electric drive assembly. The state corresponding to mode one is consistent with the operation of the electric drive assembly on the actual vehicle; the state corresponding to mode two is that the reduction 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 reduction gearbox side is connected to the main housing 15.

[0115] By collecting the front-end voltage and rear-end voltage of the motor in three modes respectively, it is possible to preliminarily analyze whether there is an electrical corrosion risk at present and the possible location of the risk when there is an electrical corrosion risk.

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

[0117] If the voltage U f1 , the voltage at the rear end of the first motor U r1 , the second motor front end voltage U f2 and the second motor rear end voltage U r2 The waveforms are all breakdown waveforms, and the voltage U f3 and the third motor rear end voltage U r3 The waveform is a common mode waveform, judging that the bearing of the current electric drive assembly has the risk of electrical corrosion on the motor side, and further judgment and corresponding countermeasures need to be made in combination with the voltage;

[0118] If the voltage U r1 , the second motor front end voltage U f2 The waveform is a common mode waveform, the voltage U f1 , the voltage at the rear end of the first motor U r1 , the third motor front end voltage U f3 and the third motor rear end voltage U r3 The waveform is a breakdown waveform, judging that the current electric drive assembly bearing has the risk of electrical corrosion on the gearbox side, and further judgment and corresponding countermeasures need to be made based on the voltage;

[0119] If the voltage U f1 , the voltage at the rear end of the first motor U r1, the second motor front end voltage U f2 , the voltage at the rear end of the second motor U r2 , the third motor front end voltage U f3 and the third motor rear end voltage U r3 The waveforms are all breakdown waveforms. It is judged that the bearings of the current electric drive assembly have the risk of electrical corrosion on the reduction gearbox side and the motor side. It is necessary to further judge and take corresponding countermeasures based on the voltage.

[0120] By analyzing the waveforms of the motor front-end voltage and the motor rear-end voltage collected during the preliminary test, it is possible to roughly determine whether the current electric drive assembly has an electrical corrosion risk. When there is an electrical corrosion risk, it determines whether the electrical corrosion risk occurs on the motor side or the reduction gearbox side, or whether there is an electrical corrosion risk on both the motor side and the reduction gearbox side.

[0121] In a further embodiment of the present application, the present embodiment further optimizes the above analysis method. When the first motor front end voltage U is obtained by preliminary testing, f1 , the voltage at the rear end of the first motor U r1 , the second motor front end voltage U f2 , the voltage at the rear end of the second motor U r2 , the third motor front end voltage U f3 and the third motor rear end voltage U r3 After that, the first step is to make a waveform judgment on the voltage value. After the waveform judgment is completed, the numerical judgment is made. That is, when judging that the bearing of the current electric drive assembly has the risk of electric corrosion on the motor side and / or the risk of electric corrosion on the gearbox side, if the voltage U f1 , the voltage at the rear end of the first motor U r1 , the second motor front end voltage U f2 , the voltage at the rear end of the second motor U r2 , the third motor front end voltage U f3 and the third motor rear end voltage U r3 If both are smaller than the allowable value of shaft voltage, it is judged that the current risk of electrical corrosion of the bearing is low and no countermeasures are needed. Otherwise, it is necessary to further judge and make corresponding countermeasures based on the voltage.

[0122] The first motor front end voltage U f1 , the voltage at the rear end of the first motor U r1 , the second motor front end voltage U f2 , the voltage at the rear end of the second motor U r2 , the third motor front end voltage U f3 and the third motor rear end voltage U r3 Both are smaller than the allowable value of shaft voltage, which proves that the voltage value collected by the preliminary test method is relatively small and is not enough to break through the oil film and cause the risk of electrical corrosion. In this case, there is no need to formulate countermeasures to eliminate the risk of electrical corrosion.

[0123] In the preferred embodiment of the present application, the present embodiment further optimizes the above analysis method. Specifically, when judging that the bearing of the current electric drive assembly has the risk of electric corrosion on the motor side, if the voltage U f1 , the voltage at the rear end of the first motor U r1 , the second motor front end voltage U f2 , the voltage at the rear end of the second motor U r2 , the third motor front end voltage U f3 and the third motor rear end voltage U r3 If the voltage is less than the allowable value of the shaft voltage (the value set according to the specification of the electric drive assembly), it proves that the voltage U f1 , the voltage at the rear end of the first motor U r1 , the second motor front end voltage U f2 , the voltage at the rear end of the second motor U r2 , the third motor front end voltage U f3 and the third motor rear end voltage U r3 At least one of the voltages exceeds the allowable value of the shaft voltage, and further testing is required.

[0124] First, the test of mode 4 is carried out. The test method of mode 4 is: 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 the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the fourth motor front end voltage U f4 and the fourth motor rear end voltage U r4 ; The state of the electric drive assembly corresponding to mode 4 is that the reduction box side is insulated, and the motor side bearing is connected to the main housing 15;

[0125] Further analysis of the test results of mode 4 shows that if the voltage at the front end of the fourth motor U f4 and the fourth motor rear end voltage U r4 If both are less than the allowable value of shaft voltage, the electric drive assembly adopts the countermeasure of adding a grounding ring at the front end of the motor, otherwise, perform mode five test.

[0126] The test method of mode five is: 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 the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the fifth motor front end voltage U f5 and the fifth motor rear end voltage U r5 ; The state of the electric drive assembly corresponding to mode five is that the reduction box side is insulated, and the motor side bearing is connected to the main housing 15;

[0127] Further analysis of the test results of mode 5 shows that if the voltage at the front end of the fifth motor Uf5 and the fifth motor rear end voltage U r5 If both are less than the allowable value of 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 6 is carried out;

[0128] The test method of mode six is: 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 the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the sixth motor front end voltage U f6 and the sixth motor rear end voltage U r6 The state of the electric drive assembly corresponding to mode six is ​​that the reduction gearbox side is insulated, and the motor side bearing is connected to the main housing 15.

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

[0130] In a further embodiment of the present application, the present embodiment further optimizes the above analysis method. Specifically, when judging that the bearing of the current electric drive assembly has the risk of electrical corrosion on the reduction gearbox side, if the voltage U f1 , the voltage at the rear end of the first motor U r1 , the second motor front end voltage U f2 , the voltage at the rear end of the second motor U r2 , the third motor front end voltage U f3 and the third motor rear end voltage U r3 If the condition that both are less than the allowable value of shaft voltage is not met, test of mode 7 is carried out;

[0131] The test method of mode seven is: connect the first measuring point 13 with both sides of the switch corresponding to the third grounding point 3, connect the second measuring point 14 with both 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 the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the front end voltage U of the seventh input shaft. a7 and the seventh input shaft rear end voltage U b7; Connect the first measuring point 13 to both sides of the switch corresponding to the fifth grounding point 5, connect the second measuring point 14 to both 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, connect the remaining grounding points, use the bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the rear end voltage U of the seventh intermediate shaft d7 and the voltage at the rear end of the seventh intermediate shaft U c7 ; Connect the first measuring point 13 to both sides of the switch corresponding to the seventh grounding point 7, connect the second measuring point 14 to both 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, connect the remaining grounding points, use the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point and the second measuring point as the front end voltage U of the seventh differential shaft f7 and the seventh differential shaft rear end voltage U e7 ;

[0132] If the voltage at the front end of the seventh input shaft U a7 , seventh input shaft rear end voltage U b7、 Voltage at the rear end of the seventh intermediate shaft U d7、 Voltage at the rear end of the seventh intermediate shaft U c7、 Seventh differential shaft front end voltage U f7、 Voltage at rear end of seventh differential shaft U e7 If both are less than the allowable value of shaft voltage, it is judged that the risk of electrical corrosion of the bearings at both ends of the axial direction of the current electric drive assembly input shaft 26 is low, and no countermeasures are required; otherwise, the test of mode eight is carried out;

[0133] The test method of mode eight is: connect the first measuring point 13 with both sides of the switch corresponding to the third grounding point 3, connect the second measuring point 14 with both 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 the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the front end voltage U of the eighth input shaft. a8 and the eighth input shaft rear end voltage U b8 ; Connect the first measuring point 13 to both sides of the switch corresponding to the fifth grounding point 5, connect the second measuring point 14 to both 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, connect the remaining grounding points, use the bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the rear end voltage U of the eighth intermediate shaft d8 and the eighth intermediate shaft rear end voltage U c8; Connect the first measuring point 13 to both sides of the switch corresponding to the seventh grounding point 7, connect the second measuring point 14 to both 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, connect the remaining grounding points, use the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point and the second measuring point as the front end voltage U of the eighth differential shaft f8 and the eighth differential shaft rear end voltage U e8 ;

[0134] If the voltage at the front end of the eighth input shaft U a8 、Voltage at the rear end of the eighth input shaft U b8 , Voltage at the rear end of the eighth intermediate shaft U d8、 Voltage at the rear end of the eighth intermediate shaft U c8 、8th differential shaft front end voltage U f8 , Voltage at the rear end of the eighth differential shaft U e8 If both are less than the allowable value of shaft voltage, the electric drive assembly adopts the countermeasure of adding a grounding ring at the front end of the motor, otherwise, the test of mode nine is carried out;

[0135] The test method of mode nine is: connect the first measuring point 13 with both sides of the switch corresponding to the third grounding point 3, connect the second measuring point 14 with both 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 the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the ninth input shaft front end voltage U a9 and the ninth input shaft rear end voltage U b9 ; Connect the first measuring point 13 to both sides of the switch corresponding to the fifth grounding point 5, connect the second measuring point 14 to both 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, connect the remaining grounding points, use the bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the rear end voltage U 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 both sides of the switch corresponding to the seventh grounding point 7, connect the second measuring point 14 to both 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, connect the remaining grounding points, use the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point and the second measuring point as the front end voltage U 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 、9th input shaft rear end voltage U b9 , the voltage at the rear end of the ninth intermediate shaft U d9, the voltage at the rear end of the ninth intermediate shaft U c9 、Ninth differential shaft front end voltage U f9 、9th differential shaft rear end voltage U e9 If both are less than the allowable value of 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 10 is carried out;

[0137] The test method of mode ten is: connect the first measuring point 13 with both sides of the switch corresponding to the third grounding point 3, connect the second measuring point 14 with both 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 the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the front end voltage U 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 both sides of the switch corresponding to the fifth grounding point 5, connect the second measuring point 14 to both 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, connect the remaining grounding points, use the bench to drag the electric drive assembly to run, and record the voltage of the first measuring point 13 and the second measuring point 14 as the rear end voltage U 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 both sides of the switch corresponding to the seventh grounding point 7, connect the second measuring point 14 to both 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, connect the remaining grounding points, use the test bench to drag the electric drive assembly to run, and record the voltage of the first measuring point and the second measuring point as the front end voltage U 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 U a10 、The voltage at the rear end of the tenth input shaft U b10 , Voltage at the rear end of the tenth intermediate shaft U d10 and the voltage U at the rear end of the tenth intermediate shaft c10 、The voltage at the front end of the tenth differential shaft U f10 and the voltage U at the rear end of the tenth differential shaft e10 If both are less than the allowable value of the 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 of adding insulating coating to the bearings in the reduction box with a value not less than the allowable value of the shaft voltage is adopted.

[0139] In other embodiments of the present application, the present embodiment further optimizes the above analysis method. Specifically, when judging that the bearings of the current electric drive assembly have the risk of electric corrosion on the motor side and the risk of electric corrosion on the reduction gearbox side, the test is performed according to Mode 7 and Mode 1. If the shaft voltages of all bearings in the electric drive assembly measured by Mode 7 and Mode 1 are less than the allowable value of the shaft voltage, no countermeasures are required; otherwise, the test is performed according to Mode 8 and Mode 4.

[0140] If the shaft voltages of all bearings in the electric drive assembly measured in mode eight and mode four are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the front end of the motor; otherwise, test according to mode nine and mode five;

[0141] If the shaft voltages of all bearings in the electric drive assembly measured in mode nine and mode five are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the rear end of the motor; otherwise, test according to mode ten and mode six;

[0142] If the shaft voltages at all bearing positions in the electric drive assembly measured in mode 10 and mode 6 are less than the allowable shaft voltage value, the shaft voltage can be reduced by installing grounding rings at both the front and rear ends of the motor.

[0143] If the shaft voltage of a bearing is always not less than the allowable shaft voltage value in the four modes, the motor bearing is replaced with a ceramic ball bearing or an insulating coating is used to insulate the bearing from the main housing 15 and the shaft in contact with it, or the reduction gearbox bearing is replaced with a ceramic ball bearing.

[0144] The present application also provides an electric drive assembly shaft voltage test system, including a grounding point module, a measuring point module, a testing module and a judgment module, wherein 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 both ends of the bearings of the input shaft 26 assembly, a fifth grounding point 5 and a sixth grounding point 6 located at both ends of the bearings of the intermediate shaft 29 assembly, a seventh grounding point 7 and an eighth grounding end located at both ends of the bearings of the differential 31 assembly, a ninth grounding point 9 and a tenth grounding point 10 located at both ends of the bearings of the motor shaft, and an eleventh grounding point 11 located at 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 realizes different test modes by controlling the on and off of the eleven grounding points, and records the voltages of the first measuring point 13 and the second measuring point 14 in each test mode as the motor front end shaft voltage and the motor rear end shaft voltage respectively; the judgment module analyzes and judges whether it is necessary to formulate corresponding countermeasures for the electric drive assembly based on the motor front end shaft voltage and the motor rear end shaft voltage.

[0145] The test 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 a mode one test method by disconnecting the first grounding point 1 and the second grounding point 2 and connecting the remaining grounding points, and records the voltages of the first measuring point 13 and the second measuring point 14 under the mode one test method as the front end voltage of the first motor and the rear end voltage of the first motor; the second module implements a mode two test 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 voltages of the first measuring point 13 and the second measuring point 14 under the mode two test method. and the voltage of the second measuring point 14 is 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 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 voltages of the first measuring point 13 and the second measuring point 14 under the mode three test method as the front-end voltage of the third motor and the rear-end voltage 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 voltages of the first measuring point 13 and the second measuring point 14 under the mode four test method. The voltage is the front-end voltage of the fourth motor and the rear-end voltage of the fourth motor; the fifth module implements the mode five 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 and disconnecting the remaining grounding points, and records the voltages of the first measuring point 13 and the second measuring point 14 under the mode five test method as the front-end voltage of the fifth motor and the rear-end voltage of the fifth motor; the sixth module implements the mode six 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 and disconnecting the remaining grounding points, and records the first measuring point 13 and the second measuring point 14 under the mode six test method. 4 is the front-end voltage of the sixth motor and the rear-end voltage of the sixth motor; the seventh module connects the first measuring point 13 to both sides of the switch corresponding to the third grounding point 3, connects the second measuring point 14 to both 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 implement 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-end voltage of the seventh input shaft, the rear-end voltage of the seventh input shaft, the front-end voltage of the seventh intermediate shaft, the rear-end voltage of the seventh intermediate shaft, the front-end voltage of the seventh differential shaft and the rear-end voltage of the seventh differential shaft;The eighth module implements the mode eight test method by connecting the first measuring point 13 to both sides of the switch corresponding to the third grounding point 3, connecting the second measuring point 14 to both sides of the switch corresponding to the fourth location, disconnecting the second grounding point 2, the third grounding point 3 and the fourth grounding point 4, and connecting the remaining grounding points, and records the voltages of the first measuring point 13 and the second measuring point 14 under the mode eight test method as the front end voltage of the eighth input shaft, the rear end voltage of the eighth input shaft, the front end voltage of the eighth intermediate shaft, the rear end voltage of the eighth intermediate shaft, the front end voltage of the eighth differential shaft, and the rear end voltage of the eighth differential shaft; the ninth module implements the mode eight test method by connecting the first measuring point 13 to both sides of the switch corresponding to the third grounding point 3, connecting the second measuring point 14 to both sides of the switch corresponding to the fourth location, disconnecting the first grounding point 1, the third grounding point 3 and the fourth grounding point 4, and connecting the remaining grounding points. The ninth test method is implemented, and the voltages of the first measuring point 13 and the second measuring point 14 under the ninth test method are recorded as the ninth input shaft front end voltage, the ninth input shaft rear end voltage, the ninth intermediate shaft front end voltage, the ninth intermediate shaft rear end voltage, the ninth differential shaft front end voltage, and the ninth differential shaft rear end voltage; the tenth module implements the tenth test method by connecting the first measuring point 13 to both sides of the switch corresponding to the third grounding point 3, connecting the second measuring point 14 to both sides of the switch corresponding to the fourth grounding point, disconnecting the third grounding point 3 and the fourth grounding point 4, and connecting the remaining grounding points, and recording the voltages of the first measuring point 13 and the second measuring point 14 under the tenth test method as the tenth input shaft front end voltage, the tenth input shaft rear end voltage, the tenth intermediate shaft front end voltage, the tenth intermediate shaft rear end voltage, the tenth differential shaft front end voltage, and the tenth differential shaft rear end voltage. ;

[0146] The judgment module includes a corrosion-free risk judgment module, a motor-side corrosion-free risk judgment module, a reduction gearbox-side corrosion risk judgment module and a two-side corrosion risk judgment module. The corrosion-free risk judgment module makes a judgment that the risk of electrical corrosion of the bearing of the current electric drive assembly is low and no countermeasures need to be formulated when 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; the motor-side corrosion-free risk judgment module makes a judgment that the bearing of the current electric drive assembly has a motor-side electrical corrosion risk and needs to be combined with the electrical 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. The voltage is further judged and corresponding countermeasures are made; when the waveforms of the second motor front end voltage and the second motor rear end voltage are common mode waveforms, and the waveforms of the first motor front end voltage, the first motor rear end voltage, the third motor front end voltage and the third motor rear end voltage are breakdown waveforms, the reduction gearbox side corrosion risk judgment module makes a judgment that the bearing of the current electric drive assembly has a reduction gearbox side electrical corrosion risk and needs to be further judged and corresponding countermeasures are made in combination with the voltage when 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. The two-side corrosion risk judgment module makes a judgment that the bearing of the current electric drive assembly has a reduction gearbox side and motor side electrical corrosion risk and needs to be further judged and corresponding countermeasures are made in combination with the voltage when 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.

[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 make a judgment that the current bearing electrical corrosion risk is low and no countermeasures need to be formulated when it is judged that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side and / or a risk of electrical corrosion on the reduction gearbox side, and 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 all less than the allowable value of the shaft voltage; the fourth countermeasure formulation module is used to make further judgments based on the front end voltage of the fourth motor and the rear end voltage of the fourth motor collected by the mode four test method when it is judged that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side and 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 not all less than the allowable value of the shaft voltage. The fifth countermeasure formulation module is used for making further judgments based on the front-end voltage of the fifth motor and the rear-end voltage of the fifth motor collected by the mode five test method when the front-end voltage of the fourth motor and the rear-end voltage of the fourth motor are both less than the allowable value of the shaft voltage, and when the front-end voltage of the fifth motor and the rear-end voltage of the fifth motor are both less than the allowable value of the shaft voltage, a countermeasure for adding a grounding ring to the rear end of the motor is formulated; the sixth countermeasure formulation module is used for making further judgments based on the front-end voltage of the sixth motor and the rear-end voltage of the sixth motor collected by the mode six test method when the front-end voltage of the fifth motor and the rear-end voltage of the fifth motor are both less than the allowable value of the shaft voltage when the front-end voltage of the fifth motor and the rear-end voltage of the fifth motor are both less than the allowable value of the shaft voltage, and when the front-end voltage of the sixth motor and the rear-end voltage of the sixth motor are both less than the allowable value of the shaft voltage, a countermeasure for adding grounding rings to the front and rear ends of the motor is formulated, otherwise a countermeasure for replacing the bearings of the electric drive assembly with ceramic ball bearings or using insulating coatings to insulate the bearings from the main housing 15 and the shaft in contact with them is formulated;The seventh countermeasure formulation module is used to make further judgments based on the seventh input shaft front end voltage, the seventh input shaft rear end voltage, the seventh intermediate shaft front end voltage and the seventh intermediate shaft rear end voltage, the seventh differential shaft front end voltage and the seventh differential shaft rear end voltage collected by the mode seven test method when it is judged that the bearing of the current electric drive assembly has the risk of electrical corrosion on the reduction gear box side and 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 not all less than the allowable value of the shaft voltage, and the seventh countermeasure formulation module is used to make further judgments based on the front end voltage of the seventh input shaft, the rear end voltage of the seventh input shaft, the front end voltage of the seventh intermediate shaft and the rear end voltage of the seventh differential shaft, and the front end voltage of the seventh differential shaft and the rear end voltage of the seventh differential shaft collected by the mode seven test method When the input shaft rear end voltage, the seventh intermediate shaft front end voltage and the seventh intermediate shaft rear end voltage, the seventh differential shaft front end voltage and the seventh differential shaft rear end voltage are all less than the allowable shaft voltage value, a judgment is made that there is no need to formulate countermeasures for the electric drive assembly reducer bearing; the eighth countermeasure formulation module is used for, when the seventh input shaft front end voltage, the seventh input shaft rear end voltage, the seventh intermediate shaft front end voltage and the seventh intermediate shaft rear end voltage, the seventh differential shaft front end voltage and the seventh differential shaft rear end voltage are all less than the allowable shaft voltage value, the eighth input shaft front end voltage and the eighth input shaft rear end voltage collected by the mode eight test method are not satisfied. The eighth input shaft front end voltage, the eighth intermediate shaft rear end voltage, the eighth differential shaft front end voltage, and the eighth differential shaft rear end voltage are further judged, and when the eighth input shaft front end voltage, the eighth input shaft rear end voltage, the eighth intermediate shaft front end voltage, the eighth differential shaft front end voltage, and the eighth differential shaft rear end voltage are all less than the shaft voltage allowable value, a countermeasure of adding a grounding ring at the front end of the motor is formulated; the ninth countermeasure formulation module is used for, when the eighth input shaft front end voltage, the eighth input shaft rear end voltage, the eighth intermediate shaft front end voltage, the eighth intermediate shaft rear end voltage, the eighth differential shaft front end voltage, and the eighth differential shaft rear end voltage are not satisfied When the front end voltage of the ninth input shaft and the rear end voltage of the eighth differential shaft are both lower 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, and when the front end voltage of the ninth input shaft and 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 are all lower than the allowable value of the shaft voltage, a countermeasure is formulated to add a grounding ring at the rear end of the motor;The tenth countermeasure formulation module is used for making further judgments based on the tenth input shaft front end voltage and the tenth input shaft rear end voltage, the tenth intermediate shaft front end voltage and the tenth intermediate shaft rear end voltage, the tenth differential shaft front end voltage and the tenth differential shaft rear end voltage collected by the mode ten test method when the situation that the ninth input shaft front end voltage, the ninth input shaft rear end voltage, the ninth intermediate shaft front end voltage and the ninth intermediate shaft rear end voltage, the ninth differential shaft front end voltage and the tenth differential shaft rear end voltage are all less than the allowable shaft voltage value, and when the tenth input shaft front end voltage and the tenth input shaft rear end voltage, the tenth intermediate shaft front end voltage and the tenth intermediate shaft rear end voltage, the tenth differential shaft front end voltage and the tenth differential shaft rear end voltage are all less than the allowable shaft voltage value, making a countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, making a countermeasure of not less than 10000V in the electric drive assembly. The countermeasure of adding insulating coating to the bearing of the allowable value of shaft voltage; the eleventh countermeasure formulation module is used for further judgment based on the front end voltage of the first motor, the rear end voltage of the first motor, the front end voltage of the seventh input shaft, the rear end voltage of the seventh input shaft, the front end voltage of the seventh intermediate shaft and the rear end voltage of the seventh intermediate shaft, the front end voltage of the seventh differential shaft and the rear end voltage of the seventh differential shaft collected by the mode one and mode seven test methods when the bearing of the current electric drive assembly has the risk of electric corrosion on the motor side and the risk of electric corrosion on the reduction gear box side, and when the front end voltage of the first motor, the rear end voltage of the first motor, the front end voltage of the seventh input shaft, the rear end voltage of the seventh input shaft, the front end voltage of the seventh intermediate shaft and the rear end voltage of the seventh intermediate shaft, the front end voltage of the seventh differential shaft and the rear end voltage of the seventh differential shaft are all less than the allowable value of shaft voltage, it is judged that there is no need to formulate countermeasures for the bearing of the electric drive assembly;

[0148] Based on the front end voltage of the fourth motor, the rear end voltage of the fourth motor, the front end voltage of the eighth input shaft, the rear end voltage of the eighth input shaft, the front end voltage of the eighth intermediate shaft, the rear end voltage of the eighth intermediate shaft, the front end voltage of the eighth differential shaft, and the rear end voltage of the eighth differential shaft collected by the mode four and mode eight test methods, further judgment is made, and when the front end voltage of the fourth motor and the rear end voltage of the fourth motor, the front end voltage of the eighth input shaft and the rear end voltage of the eighth input shaft, the front end voltage of the eighth intermediate shaft and the rear end voltage of the eighth differential shaft, the front end voltage of the eighth differential shaft, and the rear end voltage of the eighth differential shaft are all lower than the allowable value of the shaft voltage, a countermeasure of adding a grounding ring at the front end of the motor is formulated.

[0149] Based on the front end voltage of the fifth motor, the rear end voltage of the fifth motor, 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 five and mode nine test methods, further judgment is made, and when the front end voltage of the fifth motor and the rear end voltage of the fifth motor, the front end voltage of the ninth input shaft and the rear end voltage of the ninth input shaft, the front end voltage of the ninth intermediate shaft and 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 are all lower than the allowable value of the shaft voltage, a countermeasure is formulated to add a grounding ring at the front end of the motor.

[0150] Further judgment is made based on the front end voltage of the sixth motor, the rear end voltage of the sixth motor, the front end voltage of the tenth input shaft, the rear end voltage of the tenth input shaft, the front end voltage of the tenth intermediate shaft, the rear end voltage of the tenth intermediate shaft, the front end voltage of the tenth differential shaft, and the rear end voltage of the tenth differential shaft collected by the mode six and mode ten test methods, and when the front end voltage of the sixth motor and the rear end voltage of the sixth motor, the front end voltage of the tenth input shaft and the rear end voltage of the tenth input shaft, the front end voltage of the tenth intermediate shaft and the rear end voltage of the tenth intermediate shaft, the front end voltage of the tenth differential shaft, and the rear end voltage of the tenth differential shaft are all less than the allowable value of the shaft voltage, a countermeasure of adding a grounding ring at the front end of the motor is formulated;

[0151] If the shaft voltage of a bearing is always not less than the allowable shaft voltage value in the four modes, measures are taken 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, and measures are taken to replace the reduction 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 rear end refers to Figure 1 and 2 on the right side.

[0153] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application to be protected. The scope of protection claimed in the present application is defined by the attached claims and their equivalents.

Claims

1. A method for testing shaft voltage of an electric drive assembly, characterized in that: The following steps are included: 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 both ends of the bearings of the input shaft assembly, a fifth grounding point and a sixth grounding point located at both ends of the bearings of the intermediate shaft assembly, a seventh grounding point and an eighth grounding point located at both ends of the bearings of the differential assembly, a ninth grounding point and a tenth grounding point located at both ends of the bearings of the motor shaft, and an eleventh grounding point located at the main housing of the electric drive assembly; Arrange a first measuring point and a second measuring point at both ends of the motor shaft; Control the on and off of eleven grounding points to achieve different test modes, use the test bench to drag the electric drive assembly to run, and record the voltage of the first and second test points in each test mode; The voltages of the first and second measuring points recorded in each test mode are analyzed to determine whether corresponding countermeasures need to be formulated for the electric drive assembly.

2. The electric drive assembly shaft voltage testing method according to claim 1, characterized in that: The method for arranging grounding points on an electric drive assembly includes: arranging a lead-out wire on each grounding point, one end of the lead-out wire passes through a main housing and enters an insulating base at the grounding point to be connected to the corresponding grounding point, and the other end is connected to the grounding wire, and a switch is arranged on the lead-out wire.

3. The electric drive assembly shaft voltage testing method according to claim 1, characterized in that: The method of controlling the on and off of eleven grounding points to realize different test modes includes: Mode 1: disconnect the first grounding point and the second grounding point, connect the remaining grounding points, use the test bench to drag 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 of the first motor and the rear end voltage of the first motor; Mode 2: Connect the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnect the remaining grounding points, use the test bench to drag 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 of the second motor and the rear end voltage of the second motor; Mode three, disconnect the first grounding point, the second grounding point, the ninth grounding point and the tenth grounding point, connect the remaining grounding points, use the test bench to drag 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 of the third motor and the rear end voltage of the third motor.

4. The electric drive assembly shaft voltage testing method according to claim 1, characterized in that: 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 judged that the risk of electrical corrosion of the bearing 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 judged that the bearing of the current electric drive assembly has the risk of motor-side electrical corrosion, and it is necessary to further judge and make corresponding countermeasures based on the voltage; If the waveforms of the second motor front-end voltage and the second motor rear-end voltage are common-mode waveforms, and the waveforms of the first motor front-end voltage, the first motor rear-end voltage, the third motor front-end voltage, and the third motor rear-end voltage are breakdown waveforms, it is determined that the bearing of the current electric drive assembly has a risk of electrical corrosion on the reduction gearbox side, and further judgment and corresponding countermeasures need to be made based on the voltage; 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 judged that the bearings of the current electric drive assembly have the risk of electrical corrosion on the reduction gearbox side and the motor side, and further judgment and corresponding countermeasures need to be made based on the voltage.

5. The electric drive assembly shaft voltage testing method according to claim 4, characterized in that: When judging that the bearings of the current electric drive assembly have the risk of electrical corrosion on the motor side and / or the risk of electrical corrosion on the reduction gearbox side, if 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 all less than the allowable value of the shaft voltage, then it is judged that the current risk of electrical corrosion of the bearings is low and no countermeasures are needed. Otherwise, it is necessary to further judge and make corresponding countermeasures based on the voltage.

6. The electric drive assembly shaft voltage testing method according to claim 5, characterized in that: When judging that the bearing of the current electric drive assembly has the risk of electric corrosion on the motor side, if 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 do not satisfy the condition that they are all less than the allowable value of the shaft voltage, a test of mode four is performed; the test method of mode four is: connecting the first grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnecting the remaining grounding points, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the fourth motor and the rear end voltage of the fourth motor; If the voltage at the front end of the fourth motor and the voltage at the rear end of the fourth motor are both less than the allowable value of the shaft voltage, the electric drive assembly adopts the countermeasure of adding a grounding ring at the front end of the motor, otherwise, the test of mode five is carried out; The test method of mode five is: connecting the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnecting the remaining grounding points, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the fifth motor and the rear end voltage of the fifth motor; If the voltage at the front end of the fifth motor and the voltage at the rear end of the fifth motor are both 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 six is ​​carried out; The test method of mode six is: connecting the first grounding point, the second grounding point, the ninth grounding point, the tenth grounding point and the eleventh grounding point, disconnecting the remaining grounding points, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the sixth motor and the rear end voltage of the sixth motor; If the front end voltage of the sixth motor and the rear end voltage of the sixth motor are both lower than the allowable value of the shaft voltage, the electric drive assembly adopts the countermeasure of adding grounding rings at the front and rear ends of the motor. Otherwise, the bearings of the electric drive assembly are replaced with ceramic ball bearings or insulating coatings are used to insulate the bearings from the housing and shaft in contact with them.

7. The electric drive assembly shaft voltage testing method according to claim 5, characterized in that: When judging that the bearing of the current electric drive assembly has the risk of electrical corrosion on the reduction gearbox side, if 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 do not satisfy the situation that they are all less than the allowable value of the shaft voltage, the test of mode seven is performed; the test method of mode seven is: connecting the first measuring point and the two sides of the switch corresponding to the third grounding point, connecting the second measuring point and the two sides of the switch corresponding to the fourth grounding point, disconnecting the first grounding point, the second grounding point, the third grounding point and the fourth grounding point, connecting the remaining grounding points, using a test bench to drag the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the seventh input shaft and the rear end voltage of the seventh input shaft; Connect the first measuring point to both sides of the switch corresponding to the fifth grounding point, connect the second measuring point to both sides of the switch corresponding to the sixth grounding point, disconnect the first grounding point, the second grounding point, the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the test bench to drag 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 of the seventh intermediate shaft and the rear end voltage of the seventh intermediate shaft; connect the first measuring point to both sides of the switch corresponding to the seventh grounding point, connect the second measuring point to both sides of the switch corresponding to the eighth grounding point, disconnect the first grounding point, the second grounding point, the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the test bench to drag 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 of the seventh differential shaft and the rear end voltage 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, it is judged that the risk of electrical corrosion of the bearings at both ends of the axial direction of the current electric drive assembly input shaft component is low, and no countermeasures are required; otherwise, the test of mode eight is performed; The test method of the mode eight is as follows: connect the first measuring point with both sides of the switch corresponding to the third grounding point, connect the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnect the second grounding point, the third grounding point and the fourth grounding point, connect the remaining grounding points, use the 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 of the eighth input shaft and the rear end voltage of the eighth input shaft; connect the first measuring point with both sides of the switch corresponding to the fifth grounding point, connect the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnect the second grounding point, the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the 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 of the eighth intermediate shaft and the rear end voltage of the eighth intermediate shaft; connect the first measuring point with both sides of the switch corresponding to the seventh grounding point, connect the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnect the second grounding point, the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the 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 of the eighth differential shaft and the rear end voltage 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 adopts the countermeasure of adding a grounding ring at the front end of the motor, otherwise, the test of mode nine is carried out; The test method of mode nine is as follows: connect the first measuring point with both sides of the switch corresponding to the third grounding point, connect the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnect the first grounding point, the third grounding point and the fourth grounding point, connect the remaining grounding points, use the 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 of the ninth input shaft and the rear end voltage of the ninth input shaft; connect the first measuring point with both sides of the switch corresponding to the fifth grounding point, connect the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnect the first grounding point, the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the 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 of the ninth intermediate shaft and the rear end voltage of the ninth intermediate shaft; connect the first measuring point with both sides of the switch corresponding to the seventh grounding point, connect the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnect the first grounding point, the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the 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 of the ninth differential shaft and the rear end voltage 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 10 is performed; The test method of the mode ten is as follows: connect the first measuring point with both sides of the switch corresponding to the third grounding point, connect the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnect the third grounding point and the fourth grounding point, connect the remaining grounding points, use the 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 of the tenth input shaft and the rear end voltage of the tenth input shaft; connect the first measuring point with both sides of the switch corresponding to the fifth grounding point, connect the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnect the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the 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 of the tenth intermediate shaft and the rear end voltage of the tenth intermediate shaft; connect the first measuring point with both sides of the switch corresponding to the seventh grounding point, connect the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnect the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the 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 of the tenth differential shaft and the rear end voltage of the tenth differential shaft; If the front end voltage of the tenth input shaft, the rear end voltage of the tenth input shaft, the front end voltage of the tenth intermediate shaft, the rear end voltage of the tenth intermediate shaft, the front end voltage of the tenth differential shaft, and the rear end voltage of the tenth differential shaft are all lower than the allowable value of the shaft voltage, the electric drive assembly shall adopt the countermeasure of adding grounding rings at the front and rear ends of the motor; otherwise, the countermeasure of adding insulating coating to the bearings in the reduction gearbox with a value not lower than the allowable value of the shaft voltage shall be adopted.

8. The electric drive assembly shaft voltage testing method according to claim 7, characterized in that: When judging that the bearings of the current electric drive assembly have the risk of electric corrosion on the motor side and the risk of electric corrosion on the reduction gearbox side, test according to Mode 7 and Mode 1. If the shaft voltages of all bearings in the electric drive assembly measured by Mode 7 and Mode 1 are less than the allowable value of the shaft voltage, no countermeasures are required; otherwise, test according to Mode 8 and Mode 4. If the shaft voltages of all bearings in the electric drive assembly measured in mode eight and mode four are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the front end of the motor; otherwise, test according to mode nine and mode five; If the shaft voltages of all bearings in the electric drive assembly measured in mode nine and mode five are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the rear end of the motor; otherwise, test according to mode ten and mode six; If the shaft voltages of all bearings in the electric drive assembly measured in mode 10 and mode 6 are less than the allowable shaft voltage value, the shaft voltage can be reduced by installing grounding rings at both the front and rear ends of the motor; If the shaft voltage of a bearing is always not less than the allowable shaft voltage value in the four modes, the motor bearing is replaced with a ceramic ball bearing or an insulating coating is used to insulate the bearing from the housing and shaft in contact with it, or the reduction gearbox bearing is replaced with a ceramic ball bearing.

9. An electric drive assembly shaft voltage test system, characterized in that: The test system is operated according to any one of the electric drive assembly shaft voltage test methods according to claims 1 to 8, including: A grounding point module, the grounding point 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 both ends of the bearings of the input shaft assembly, a fifth grounding point and a sixth grounding point located at both ends of the bearings of the intermediate shaft assembly, a seventh grounding point and an eighth grounding point located at both ends of the bearings of the differential assembly, a ninth grounding point and a tenth grounding point located at both ends of the bearings of the motor shaft, and an eleventh grounding point located at the main housing of the electric drive assembly; A measuring point module, the measuring point module comprising a first measuring point and a second measuring point located at two axial ends of the motor shaft; A test module, wherein the test module realizes different test modes by controlling the on and off of eleven grounding points, and records the voltage of the first test point and the second test point in each test mode; A judgment module is used to analyze and judge whether it is necessary to formulate corresponding countermeasures for the electric drive assembly based on the voltage of the first measurement point and the second measurement point in each test mode.

10. The electric drive assembly shaft voltage test system according to claim 9, characterized in that: The test module includes: A first module, wherein the first module implements a mode one 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 measuring point and the second measuring point under the mode one test method as a first motor front end voltage and a first motor rear end voltage; The second module implements the mode 2 test method by connecting 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 measuring point and the second measuring point under the mode 2 test method as the front end voltage of the second motor and the rear end voltage of the second motor; A third module, wherein the third module implements a 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 measuring point and the second measuring point under the mode three test method as a front end voltage of the third motor and a rear end voltage of the third motor; A fourth module, wherein the fourth module implements a mode four 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 measuring point and the second measuring point under the mode four test method as a front end voltage of the fourth motor and a rear end voltage of the fourth motor; A fifth module, wherein the fifth module implements a 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 measuring point and the second measuring point under the mode five test method as a front end voltage of the fifth motor and a rear end voltage of the fifth motor; A sixth module, wherein the sixth module implements a mode six 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 measuring point and the second measuring point under the mode six test method as a front end voltage of the sixth motor and a rear end voltage of the sixth motor; The seventh module implements the mode seven test method by connecting the first measuring point with both sides of the switch corresponding to the third grounding point, connecting the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnecting the first grounding point, the second grounding point, the third grounding point and the fourth grounding point, and connecting the remaining grounding points, and recording the voltages of the first measuring point and the second measuring point under the mode seven test method as the front end voltage of the seventh input shaft and the rear end voltage of the seventh input shaft; connecting the first measuring point with both sides of the switch corresponding to the fifth grounding point, connecting the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnecting the first grounding point and the second grounding point, and connecting the second grounding point and the sixth grounding point. , the fifth grounding point and the sixth grounding point, connect the remaining grounding points, use the test bench to drive the electric drive assembly to run, record the voltages of the first measuring point and the second measuring point as the front end voltage of the seventh intermediate shaft and the rear end voltage of the seventh intermediate shaft; connect the first measuring point with both sides of the switch corresponding to the seventh grounding point, connect the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnect the first grounding point, the second grounding point, the seventh grounding point and the eighth grounding point, connect the remaining grounding points, use the test bench to drive the electric drive assembly to run, record the voltages of the first measuring point and the second measuring point as the front end voltage of the seventh differential shaft and the rear end voltage of the seventh differential shaft; The eighth module implements the mode eight test method by connecting the first measuring point with both sides of the switch corresponding to the third grounding point, connecting the second measuring point with both sides of the switch corresponding to the fourth grounding point, disconnecting the second grounding point, the third grounding point and the fourth grounding point, and connecting the remaining grounding points, and records the voltages of the first measuring point and the second measuring point under the mode eight test method as the front end voltage of the eighth input shaft and the rear end voltage of the eighth input shaft; connecting the first measuring point with both sides of the switch corresponding to the fifth grounding point, connecting the second measuring point with both sides of the switch corresponding to the sixth grounding point, disconnecting the second grounding point, the fifth grounding point and the sixth grounding point, connecting the remaining grounding points, using the test bench to drive the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the eighth intermediate shaft and the rear end voltage of the eighth intermediate shaft; connecting the first measuring point with both sides of the switch corresponding to the seventh grounding point, connecting the second measuring point with both sides of the switch corresponding to the eighth grounding point, disconnecting the second grounding point, the seventh grounding point and the eighth grounding point, connecting the remaining grounding points, using the test bench to drive the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the eighth differential shaft and the rear end voltage of the eighth differential shaft; The ninth module implements the mode nine test method by connecting the first measuring point to both sides of the switch corresponding to the third grounding point, connecting the second measuring point to both sides of the switch corresponding to the fourth grounding point, disconnecting the first grounding point, the third grounding point and the fourth grounding point, and connecting the remaining grounding points, and records the voltages of the first measuring point and the second measuring point under the mode nine test method as the front end voltage of the ninth input shaft and the rear end voltage of the ninth input shaft; connecting the first measuring point to both sides of the switch corresponding to the fifth grounding point, connecting the second measuring point to both sides of the switch corresponding to the sixth grounding point, disconnecting the first grounding point, the fifth grounding point and the sixth grounding point, connecting the remaining grounding points, using the test bench to drive the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the ninth intermediate shaft and the rear end voltage of the ninth intermediate shaft; connecting the first measuring point to both sides of the switch corresponding to the seventh grounding point, connecting the second measuring point to both sides of the switch corresponding to the eighth grounding point, disconnecting the first grounding point, the seventh grounding point and the eighth grounding point, connecting the remaining grounding points, using the test bench to drive the electric drive assembly to run, and recording the voltages of the first measuring point and the second measuring point as the front end voltage of the ninth differential shaft and the rear end voltage of the ninth differential shaft; The tenth module implements the mode ten test method by connecting the first measuring point to both sides of the switch corresponding to the third grounding point, connecting the second measuring point to both sides of the switch corresponding to the fourth location, disconnecting the third grounding point and the fourth grounding point, and connecting the remaining grounding points, and records the voltages of the first measuring point and the second measuring point under the mode ten test method as the front end voltage of the tenth input shaft and the rear end voltage of the tenth input shaft; connects the first measuring point to both sides of the switch corresponding to the fifth grounding point, connects the second measuring point to both sides of the switch corresponding to the sixth location, disconnects the fifth grounding point and the sixth grounding point, connects the remaining grounding points, uses a test bench to drive the electric drive assembly to run, and records the voltages of the first measuring point and the second measuring point as the front end voltage of the tenth intermediate shaft and the rear end voltage of the tenth intermediate shaft; connects the first measuring point to both sides of the switch corresponding to the seventh grounding point, connects the second measuring point to both sides of the switch corresponding to the eighth location, disconnects the seventh grounding point and the eighth grounding point, connects the remaining grounding points, uses a test bench to drive the electric drive assembly to run, and records the voltages of the first measuring point and the second measuring point as the front end voltage of the tenth differential shaft and the rear end voltage of the tenth differential shaft.

11. The electric drive assembly shaft voltage test system according to claim 10, characterized in that: The judging module comprises: a corrosion-free risk judgment module, wherein the corrosion-free risk judgment module judges that the risk of electrical corrosion of the bearing of the current electric drive assembly is low and no countermeasures need to be formulated when 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; A motor-side corrosion-free risk judgment module, wherein 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, the motor-side corrosion-free risk judgment module makes a judgment that the bearing of the current electric drive assembly has a motor-side electrical corrosion risk and needs to be further judged in combination with the voltage and corresponding countermeasures are taken; A reduction gearbox side corrosion risk judgment module, wherein when the waveforms of the second motor front end voltage and the second motor rear end voltage are common mode waveforms, and the waveforms of the first motor front end voltage, the first motor rear end voltage, the third motor front end voltage and the third motor rear end voltage are breakdown waveforms, the reduction gearbox side corrosion risk judgment module makes a judgment that the bearing of the current electric drive assembly has a reduction gearbox side electrical corrosion risk and needs to be further judged in combination with the voltage and corresponding countermeasures are taken; A corrosion risk judgment module on both sides, when 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, makes a judgment that the bearings of the current electric drive assembly have electrical corrosion risks on the reduction gearbox side and the motor side, and further judgment and corresponding countermeasures need to be made based on the voltage.

12. The electric drive assembly shaft voltage test system according to claim 11, characterized in that: The judging module also includes: A no-countermeasure formulation module, wherein the no-countermeasure formulation module is used to make a judgment that the current bearing electrical corrosion risk is low and no countermeasures are required when it is judged that the bearing of the current electric drive assembly has a risk of electrical corrosion on the motor side and / or a risk of electrical corrosion on the reduction gearbox side, and 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 less than the allowable value of the shaft voltage; A fourth countermeasure formulation module, wherein the fourth countermeasure formulation module is used to make further judgments based on the fourth motor front end voltage and the fourth motor rear end voltage collected by the mode four test method when it is judged that the bearing of the current electric drive assembly has a risk of electric corrosion on the motor side and 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 not all less than the allowable value of the shaft voltage, and when the fourth motor front end voltage and the fourth motor rear end voltage are both less than the allowable value of the shaft voltage, formulate a countermeasure of adding a grounding ring to the front end of the motor; A fifth countermeasure formulation module, wherein the fifth countermeasure formulation module is used to make further judgments based on the fifth motor front end voltage and the fifth motor rear end voltage collected by the mode five test method when the fourth motor front end voltage and the fourth motor rear end voltage are both less than the shaft voltage allowable value, and formulate a countermeasure of adding a grounding ring at the rear end of the motor when the fifth motor front end voltage and the fifth motor rear end voltage are both less than the shaft voltage allowable value; The sixth countermeasure formulation module is used to make further judgments based on the front-end voltage of the sixth motor and the rear-end voltage of the sixth motor collected by the mode six test method when the situation that the front-end voltage of the fifth motor and the rear-end voltage of the fifth motor are both less than the allowable value of the shaft voltage is not satisfied, and to formulate a countermeasure of adding grounding rings at the front and rear ends of the motor when the front-end voltage of the sixth motor and the rear-end voltage of the sixth motor are both less than the allowable value of the shaft voltage, otherwise, a countermeasure of replacing the bearings of the electric drive assembly with ceramic ball bearings or using insulating coatings to insulate the bearings from the housing and shaft in contact with them is formulated.

13. The electric drive assembly shaft voltage test system according to claim 11, characterized in that: The judging module also includes: A seventh countermeasure formulation module, wherein the seventh countermeasure formulation module is used to make further judgments based on the seventh input shaft front end voltage, the seventh input shaft rear end voltage, the seventh intermediate shaft front end voltage, the seventh intermediate shaft rear end voltage, the seventh differential shaft front end voltage, and the seventh differential shaft rear end voltage collected by the mode seven test method when it is judged that the bearing of the current electric drive assembly has a risk of electrical corrosion on the reduction gearbox side and 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 not all less than the allowable value of the shaft voltage, and when the front end voltage of the seventh input shaft, the rear end voltage of the seventh input shaft, the front end voltage of the seventh intermediate shaft, the rear end voltage of the seventh intermediate shaft, the front end voltage of the seventh differential shaft, and the rear end voltage of the seventh differential shaft are all less than the allowable value of the shaft voltage, make a judgment that there is no need to formulate countermeasures for the reduction gearbox bearing of the electric drive assembly; an eighth countermeasure formulation module, wherein the eighth countermeasure formulation module is used for making further judgments based on the eighth input shaft front end voltage, the eighth input shaft rear end voltage, the eighth intermediate shaft front end voltage, the eighth intermediate shaft rear end voltage, the eighth differential shaft front end voltage, and the eighth differential shaft rear end voltage collected by the mode eight test method when the seventh input shaft front end voltage, the seventh input shaft rear end voltage, the seventh intermediate shaft front end voltage, the seventh intermediate shaft rear end voltage, the seventh differential shaft front end voltage, and the eighth differential shaft rear end voltage are all less than the shaft voltage allowable value, and when the eighth input shaft front end voltage, the eighth input shaft rear end voltage, the eighth intermediate shaft front end voltage, the eighth intermediate shaft rear end voltage, the eighth differential shaft front end voltage, and the eighth differential shaft rear end voltage are all less than the shaft voltage allowable value, formulating a countermeasure of adding a grounding ring to the front end of the motor; a ninth countermeasure formulation module, wherein the ninth countermeasure formulation module is used for making further judgments based on the ninth input shaft front end voltage, the ninth input shaft rear end voltage, the ninth intermediate shaft front end voltage, the ninth intermediate shaft rear end voltage, the ninth differential shaft front end voltage, and the ninth differential shaft rear end voltage collected by the mode nine test method when the eighth input shaft front end voltage, the eighth input shaft rear end voltage, the eighth intermediate shaft front end voltage, the eighth intermediate shaft rear end voltage, the eighth differential shaft front end voltage, and the ninth differential shaft rear end voltage are all less than the shaft voltage allowable value, and when the ninth input shaft front end voltage, the ninth input shaft rear end voltage, the ninth intermediate shaft front end voltage, the ninth intermediate shaft rear end voltage, the ninth differential shaft front end voltage, and the ninth differential shaft rear end voltage are all less than the shaft voltage allowable value, formulating a countermeasure of adding a grounding ring at the rear end of the motor; The tenth countermeasure formulation module is used for making further judgments based on the tenth input shaft front end voltage, the tenth input shaft rear end voltage, the tenth intermediate shaft front end voltage, the tenth intermediate shaft rear end voltage, the tenth differential shaft front end voltage, and the tenth differential shaft rear end voltage collected by the mode ten test method when the situation that the ninth input shaft front end voltage and the ninth input shaft rear end voltage, the ninth intermediate shaft front end voltage, the ninth intermediate shaft rear end voltage, the ninth differential shaft front end voltage, and the ninth differential shaft rear end voltage are all less than the allowable shaft voltage. When the tenth input shaft front end voltage, the tenth input shaft rear end voltage, the tenth intermediate shaft front end voltage, the tenth intermediate shaft rear end voltage, the tenth differential shaft front end voltage, and the tenth differential shaft rear end voltage are all less than the allowable shaft voltage, a countermeasure of adding grounding rings at the front and rear ends of the motor is formulated; otherwise, a countermeasure of adding insulating coatings at bearings in the electric drive assembly that are not less than the allowable shaft voltage value is formulated.

14. The electric drive assembly shaft voltage test system according to claim 13, characterized in that: The judging module also includes: The eleventh countermeasure formulation module is used for testing according to mode seven and mode one when the bearings of the current electric drive assembly have the risk of electric corrosion on the motor side and the risk of electric corrosion on the reduction gearbox side. If the shaft voltages of all bearings in the electric drive assembly measured by mode seven and mode one are less than the allowable value of the shaft voltage, no countermeasures are required; otherwise, the test is performed according to mode eight and mode four; If the shaft voltages of all bearings in the electric drive assembly measured in mode eight and mode four are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the front end of the motor; otherwise, test according to mode nine and mode five; If the shaft voltages of all bearings in the electric drive assembly measured in mode nine and mode five are less than the allowable shaft voltage value, the shaft voltage is reduced by installing a grounding ring at the rear end of the motor; otherwise, test according to mode ten and mode six; If the shaft voltages of all bearings in the electric drive assembly measured in mode 10 and mode 6 are less than the allowable shaft voltage value, the shaft voltage can be reduced by installing grounding rings at both the front and rear ends of the motor; If the shaft voltage of a bearing is always not less than the allowable shaft voltage value in the four modes, a countermeasure is formulated to replace the motor bearing with a ceramic ball bearing or use an insulating coating to insulate the bearing from the housing and shaft in contact with it, and a countermeasure is formulated to replace the reduction box bearing with a ceramic ball bearing.

Images