EV motor EMC test bench, motor controller EMI test stand

 

With the rapid development of electric drive systems, especially new energy saving vehicles, the issue of electromagnetic compatibility has received more and more attention. The electric drive system of new energy saving vehicles have the characteristics of high voltage, high current, complex structure and diversified coupling paths. Those are the main source of interference.

For this reason, the through-the-wall-type EV motor EMC test bench, motor controller EMI test stand with loading in anechoic chamber came into being. The measurement is applicable to EMC test items for automotive parts, including electric motor, motor controller, battery and high voltage components for electric vehicles such as pure electric drives and hybrid drive assemblies. It conforms to national standards CISPR, GB and GB/T. These standards not only define the test conditions, but also define the allowable level of radiation emission of the device under test.

 

EV motor EMC test bench, motor controller EMI test stand

 

EV motor EMC test bench, motor controller EMI test stand under simulated actual load conditions are composed of an anechoic chamber, dynamometer system, battery simulator, power amplifier and its shielding room, control room and its shielding room, cooling system and shielding shaft system. According to CISPR 25, GB/T 18655, GB/T 36282, GB/T 18387 and other standards, it can meet the test of conducted emission, radiated emission and radiated immunity, high current injection of battery packs, motors, controllers and powertrains, etc.

 

EV motor EMC test bench, motor controller EMI test stand

 

Direct drive dynamometer system

 

The direct drive dynamometer system can perform EMC/ EMI tests on high-speed motors and controllers. The high-speed motor is installed on the end face of the L-shaped tooling or on the T-slot platform. The controller is placed on the test table. It can also test the products where the motor and the controller are integrated. According to the actual parameters of the motor to be tested, the corresponding dynamometer can be selected.

 

Direct drive dynamometer of motor EMC test bench
Direct drive dynamometer of motor EMI/ EMC test bench

 

The recommended dynamometer parameters are as follows:

 

ModelRated power (kW)Rated torque (Nm)Max. speed (rpm)
EMC-DD-011204587500
EMC-DD-0217343015000
EMC-DD-0325050016000
EMC-DD-0430057015000
EMC-DD-05300100012000
EMC-DD-06300200010000
EMC-DD-07300130010000
EMC-DD-0830018009000
EMC-DD-0937040007000
EMC-DD-1050045006000

 

The dynamometer parameters can also be customized according to the actual needs of users.

 

Direct drive dynamometer of motor controller EMI/ EMC test bench

 

The shaft system of the direct drive dynamometer system is simple. The reflection surface of the installation tooling of the tested motor is small, which has little influence on the measurement uncertainty. When testing the electric drive assembly, the differential can be locked, and one side shaft is connected to the dynamometer shaft system.

 

Electric drive and powertrain universal dynamometer system

 

The EV motor EMC test bench, motor controller EMI test stand can take into account EMC/ EMI testing of high-speed motors, low-speed high-torque powertrains, and low-speed high-torque motors. A medium-speed high-torque dynamometer is used to connect a dual-output gearbox. The high-speed shaft of the gearbox can be increased to higher speed through gear transmission, and the low-speed shaft can be directly output by the dynamometer.

 

Electric drive and powertrain universal dynamometer system for EMC test

 

Electric drive and powertrain universal EMC test system load dynamometer parameters:

 

ModelRated power (kW)Rated torque (Nm)Max. speed (rpm)
EMC-U-0137040006000
50020000
EMC-U-0248045006000
50020000

 

The dynamometer parameters can also be customized according to the actual needs of users.

This configuration of EV motor EMC test bench, motor controller EMI test stand can take into account both high-speed, low-torque and low-speed, high-torque electric drive system testing. However, due to the addition of a high-speed gearbox, the area of the mounting surface of the motor to be tested will be increased. Increasing the area of the reflecting surface will have a certain impact on the measurement uncertainty. The product provided by our company has the following designs:

 

  1. The oil and gas absorption device of the high-speed gearbox is designed to prevent the oil and gas from volatilizing into the anechoic chamber.
  2. The dynamometer is a medium-speed high-torque dynamometer. It can significantly reduce the transmission ratio of the gearbox and reduce the center distance. The cross-sectional area of the gearbox and the impact on measurement uncertainty can be reduced.
  3. The gearbox lubrication system is designed with the function of continuing to supply oil after power failure. It can maintain the continuous oil supply capacity for at least 5 minutes to prevent the gearbox from being damaged by oil cut.
  4. The gearbox lubrication system is designed with a constant temperature device, which can keep the gearbox oil inlet temperature constant. It can reduce the influence of lubricating oil viscosity on transmission efficiency and eliminate torque measurement errors causing by transmission efficiency fluctuations.

 

Dual-axis loading dynamometer system

 

The dual-axis load dynamometer system of EV motor EMC test bench, motor controller EMI test stand can simulate the installation state of the actual vehicle powertrain to the greatest extent. The differential is not locked or welded. The output shafts on both sides of the powertrain can be replaced with on-board half shafts. The wheel spacing can be the same as the actual vehicle. The system can also meet the EMC test of passenger car motors with maximum speed of 12,000 rpm and rated torque of 1,000 Nm.

 

Dual-axis loading dynamometer system for motor controller EMC test bench

 

ModelRated power (kW)Rated torque (Nm)Max. speed (rpm)
EMC-DA-01300100012000
EMC-DA-0237035003000

 

The dynamometer parameters can also be customized according to the actual needs of users.

The system can be designed to be insulated from the ground on both sides of the powertrain under test for simulating the state of vehicle tires.

The low-speed shaft side shaft system can be removed for high-speed motor testing.

 

High-speed motor testing for controller EMI/ EMC test bench

 

For dual-axis dynamometers with limited space in the anechoic chamber, the right-angle transmission can also be used.

Right-angle transmission dynamometers in anechoic chamber

Mobile electric drive dynamometer system

 

The mobile powertrain loading dynamometer system adopts a modular structure. Each unit body is a movable structure. When a test is needed, just push each unit of the dynamometer to the corresponding position in the anechoic chamber, and quickly connect and lock it to start the test. The mobile powertrain load dynamometer system inverter, cooling system, battery simulator, etc. are all placed outside the anechoic chamber. The filter is connected to the junction box in the anechoic chamber.

The connection to the dynamometer is realized by a quick connector. The mobile powertrain loading dynamometer and the powertrain are connected by a half shaft. The axle spacing is close to the actual wheelbase and is adjustable, and the adjustment range can be customized. The installation state of the real vehicle is simulated to the greatest extent.

Mobile electric drive dynamometer system

The dynamometer parameters:

ModelRated power (kW)Rated torque (Nm)Max. speed (rpm)
EMC-M-0111510982000

 

The dynamometer parameters can also be customized according to the actual needs of users.




Detailed technical description of EV motor EMC test bench, motor controller EMI test stand

 

System Architecture

 

The EV motor EMC test bench, motor controller EMI test stand is generally composed of electric wave anechoic chamber, dynamometer system and measuring instrument. We generally provide anechoic chamber and dynamometer system. The anechoic chamber can be a standard CISPR 25 anechoic chamber. The dynamometer system needs to be determined according to the parameters of the product to be tested. The dynamometer system generally includes: AC dynamometer that simulates load, through-wall shielding shaft system, installation stand, frequency converter, battery simulator, cooling system, sensor measurement system, data acquisition system, monitoring software and other parts.

 

CISPR 25 anechoic chamber system architecture

 

Key technical indicators

 

  1. Shielding effectiveness

     

    The shielding effectiveness of the EV motor EMC test bench, motor controller EMI test stand loading CISPR 25 anechoic chamber, control room, and power amplifier room is implemented in accordance with the standard EN50147-1 or the latest standard GB/T12190 (frequency range 10KHz~18GHz). The specific test frequency is determined according to the test frequency of the third-party testing agency, and meets the following indicators:

     

    FrequencyAttenuationField source
    10 kHz≥70 dBMagnetic field
    10 kHz≥100 dBElectric field
    100 kHz≥100 dBMagnetic field
    100 kHz≥110 dBElectric field
    1 MHz≥100 dBMagnetic field
    1 MHz≥110 dBElectric field
    100 MHz≥110 dBElectric field
    400 MHz≥110 dBPlane wave
    1 GHz≥100 dBPlane wave
    10 GHz≥100 dBPlane wave
    18 GHz≥100 dBPlane wave

     

    After installation of all related accessories (including wall shaft) is completed, the EV motor EMC test bench, motor controller EMI test stand works (small non-radiation load can be provided). When the monitoring system, lamps, antenna tower are working, and the filter is energized, the shielding effectiveness is at least 10dB lower than the Class 5 limit (PK, QP, AV) specified by CISPR 25.

 

  1. Measurement control accuracy

     

    • Torque measurement accuracy: ±0.05% FS
    • Pulse resolution of speed sensor: 1024ppr/ 600ppr
    • Torque control accuracy: ±1%
    • Speed control accuracy: ±0.01% FS
    • Maximum vibration speed value of dynamometer (RSM): ≤ 2mm/s (independent), ≤ 3.5mm/s (loading)
    • Temperature rise of intermediate bearing seat: ≤35℃
    • Maximum vibration velocity value of intermediate bearing seat (RSM): ≤2mm/s (independent), ≤3.5mm/s (loading)
    • Sampling rate of data acquisition system: 1 kHz
    • User data acquisition system channel: optional
    • Temperature measurement range: -50℃ ~ 200℃
    • Vibration sensor measuring range (RSM): 0 ~ 20mm/s

 

  1. Long Wire Method (LWM)

     

    According to the latest version of CISPR 25, the modelled long wire antenna method (LWM) is adopted in the frequency range of 150kHz~1GHz. The error of more than 90% of the actual test points and the theoretical value of the model is not more than ±6dB. The test area is the motor side and the non-motor side. The test invites an authoritative third-party measurement agency to conduct the test and provide a report.

 

  1. Background noise (ABN)

     

    When there is no DUT, monitoring system, lamps, and filters are energized, in the range of 9KHz~6GHz, the test background noise level should be at least lower than the level of the Class 5 limit (PK, QP, AV) specified in the latest version of CISPR 25 10dB. At the same time, it is at least 6dB lower than the GJB 151B RE 102 limit. This test invites a third-party measurement agency certified by the national authority to conduct the test and provide a report.

 

  1. Air quality

     

    After the construction of the radio anechoic chamber is completed, the testing agency is invited to conduct air quality testing in the anechoic chamber and issue a test report on the air quality of the anechoic chamber (including at least formaldehyde, benzene, toluene, dimethylbenzene and TVOC).

 

  1. Grounding resistance

     

    The anechoic chamber and the shielding room are grounded by a single point grounding method, and the grounding resistance is designed and constructed by us. The grounding device process uses physical resistance reducers and does not use chemical resistance reducers. The grounding device is designed to be maintainable. The grounding resistance of dark room and shielded room is less than 1Ω.

 

 

Implementation standards

 

  • CISPR 16-1-4 “Specification for radio disturbance and immunity measuring apparatus and methods – Part 1-4: Radio disturbance and immunity measuring apparatus – Antennas and test sites for radiated disturbance measurements”
  • CNAS-CL01-A008 “Guidance on the application of testing and calibration laboratories competence accreditation criteria in the field of electromagnetic compatibility testing”
  • EN 50147 “Anechoic chambers Part 1: Shield attenuation measurement”
  • GB/T 12190 “Method for measuring the shielding effectiveness of electromagnetic shielding enclosures”
  • ISO 4589-2 “Plastics-Determination of burning behaviour by oxygen index –Part 2: Ambient-temperature test”
  • GB/T 2406 “Plastics Determination of flammability by oxygen index”
  • GB 8624 “Classification for burning behaviour of building materials and products”
  • ISO 11452 “Road vehicles — Component test methods for electrical disturbances from narrowband radiated electromagnetic energy”
  • CISPR 25 “Vehicles, boats and internal combustion engines – Radio disturbance characteristics – Limits and methods of measurement for the protection of on-board receivers”
  • MIL-STD-461G “Requirements for the control of electromagnetic interference characteristics of subsystems and equipment”
  • GJB 151B “Requirements and measurements of electromagnetic emission and sensitivity of military equipment and subsystems”
  • GBT 36282-2018 “Electromagnetic compatibility requirements and test methods of drive motor system for electric vehicles”
  • GB 50325-2010 “Code for indoor environmental pollution control of civil building engineering”
  • GB/T 18883-2002 “Indoor air quality standard”




Key technology description

 

The key technologies of the EV motor EMC test bench, motor controller EMI test stand include: high-speed through-wall shielding shafting, complete electrical isolation system, anechoic chamber non-radiation sensor monitoring system, low-noise battery simulator and other systems, real-time monitoring system and other parts.

 

  1. High-speed through-wall shielding shafting

     

    The CISPR 25 standard clearly requires that the distance between the EUT of the controller and the center of the absorbing material is not less than 1m. For the three-in-one electric drive powertrain, the distance between the inner side of the controller (near the anechoic chamber side) and the top of the absorbing material is not less than 1m, and the distance between the mounting end of the motor drive powertrain and the top of the absorbing material is not less than 1m.

    In order to meet this requirement, the length of the shaft system is longer, and at the same time, it needs to meet the requirement of less vibration at high speed. The current international solution is to use carbon fiber shafts or glass fiber shafts. The test conditions require that the length of the shaft must be greater than 1.6 meters. (International standards stipulate that the distance between the end face of the motor under test and the top of the anechoic chamber absorbing material should not be less than 1m, taking into account the thickness of the absorbing material, the thickness of ferrite, and the thickness of the shield, and also taking into account the installation error).

    Although these two non-metal shafts are excellent non-conductive and non-magnetic materials, however, the electric drive system of energy saving vehicles have entered the high-speed and high-torque stage, the absolute elastic modulus of the glass fiber shaft or carbon fiber shaft is not suitable for high-speed and high-torque testing.


    CISPR 25 test layout

    Test layout defined by CISPR 25

     

    The high-speed through-wall shielding shaft of EV motor EMC test bench, motor controller EMI test stand designed by Dyno Equip has the following characteristics:

     

      • Using high-precision and low-inertia rigid shafts while taking into account the characteristics of high speed and large torque.
      • As a part of the anechoic chamber, the rotating shaft has good conductivity and fundamentally shields external electromagnetic radiation, achieving excellent shielding effect and reducing background noise in the anechoic chamber.
      • Through the detachable shielding cover, the test motor can be completely shielded and the electromagnetic compatibility characteristics of the drive axle can be tested independently.

    High-speed, long-shaft for EMC/ EMI test

    In order to meet the high-speed, high-torque and shielding requirements at the same time, the system adopts a high-precision long-shaft system.

     

      • The vibration speed in the full speed range is less than 3.5mm/s.
      • The shaft system adopts a multi-point support structure, which is convenient for the base alignment in the anechoic chamber and the coaxiality is better than 0.02mm.
      • The shaft system has a fully dynamic balance structure, and the dynamic balance accuracy reaches G1.
      • The first-order critical speed of the shaft system is higher than the maximum speed of the system.

 

  1. Completely electrically isolated system

     

    In order to prevent electromagnetic waves and charges from being conducted outside the anechoic chamber to the anechoic chamber, in addition to special electromagnetic shielding methods, the dynamometer of EV motor EMC test bench, motor controller EMI test stand must be completely electrically isolated. Electric drive motors or powertrains need to meet the single-point grounding requirements.

     

    • The dynamometer and the shielded shaft adopt high-speed insulation coupling.
    • The dynamometer is completely electrically isolated from the base.
    • The high-speed shielded shaft and the tested electric drive motor shaft adopt high-speed insulation coupling.
    • The installation base in the anechoic chamber is completely electrically isolated from the anechoic chamber.
    • The anechoic chamber is designed with a removable complete shielding cover, which can completely shield the motor and test the EUT of the controller individually.

 

  1. Non-radiation sensor monitoring system in anechoic chamber

     

    The electric drive system and shaft system under test in the anechoic chamber are designed with vibration and temperature monitoring sensors. The sensor needs to be collected by high-speed data acquisition system and transmitted to the monitoring software for signal analysis and processing. The data acquisition system is placed in the anechoic chamber. Due to its own radiation, the background noise of the anechoic chamber will be affected, and low noise processing is required.

    Our company has made the following designs for the data acquisition system in the anechoic chamber:

     

    • The power supply of the data acquisition system is filtered through a 24V filter to eliminate the power interference entering the anechoic chamber.
    • The signal transmission design of the data acquisition system is a real-time Ethernet optical fiber converter. The signal is transmitted to the anechoic chamber through the optical fiber and the optical fiber waveguide installed on the wall of the anechoic chamber, the signal is then converted into a digital signal by an inverse converter and enters the host computer.
    • The data acquisition system is installed in a shielded box. The shielded box is designed with ventilation waveguides to ensure heat dissipation and at the same time ensure that the electromagnetic waves in the box will not be transmitted to the anechoic chamber.
    • The sensor cable adopts a special shielded cable, which connects the sensor and the shielded box as a whole.

 

  1. Low noise battery simulator

     

    The battery simulator supplies power to the motor controller under test, simulates the battery and can also perform battery pack charge and discharge tests.

     

    • Output voltage:
      • Maximum output voltage (Unom ): 1200V
      • Output voltage range: 20V~Unom adjustable, setting resolution: 0.1V
      • Repeatability: ≤0.1% Unom
      • Voltage rise time (10% to 90% Unom ): <5ms (resistive load)
      • Control time of load change (10% to 90%): ≤ 1ms (resistive load)
      • Residual ripple: ≤0.2% Unom effective value (frequency DC-1MHz)
    • Output current:
      • Maximum output current (Inom ): 800A
      • Output current range: 0 ~ Inom adjustable, setting resolution: 0.1A
      • Repeatability: ≤0.1% Inom
      • Current rise time (10% to 90% Inom ): <1ms (resistive load)
      • Load change (10% to 90%) control time: ≤ 1ms (resistive load)
      • Temperature coefficient: ≤0.01% Inom/K
      • Residual ripple: ≤0.2% Inom effective value (frequency DC-1MHz)
    • Output power: ±350kW
    • Output efficiency: >90%
    • Output accuracy: 0.1%
    • Internal resistance:
      • Setting range: 0~5Ω (adjustment resolution 0.1mΩ)
      • Battery mode: by adjusting internal resistance

     

    The parameters of the battery simulator can be customized according to actual needs.

 

  1. Real-time monitoring system

     

    The monitoring system adopts embedded real-time controller control, real-time Ethernet communication, and all communication cables entering the control room are transmitted through optical fibers.

     

      • The front bearings, rear bearings and temperature of the dynamometer are monitored in real time. The current and voltage of the dynamometer are monitored in real time, and the speed and torque of the dynamometer are monitored in real time.
      • Real-time vibration monitoring of the shielded long shaft.
      • Real-time vibration monitoring of the motor under test.
      • The electronic control system has protection functions such as short circuit, leakage, power failure, overcurrent, and overvoltage.
      • The system software has a safety detection function. When the monitoring value exceeds the threshold, it will immediately alarm. The system has three levels of protection.
      • The anechoic chamber uses the data acquisition system with non-electromagnetic radiation photoelectric isolation. Vibration sensor and temperature sensor signals are collected in real time. The signals are transmitted to the control room through optical fiber for real-time monitoring.
      • Emergency stop buttons are designed near the test table in the anechoic chamber, in the control room, and near the dynamometer.

     

    Real-time monitoring system of electrical motor EMI/ EMC test bench
    Real-time monitoring system of electrical motor EMI/ EMC dynamometer

 

  1. Special interface

     

    • The design frequency range of the water or oil waveguide is 9kHz ~ 18GHz, which achieves the same shielding effectiveness as the anechoic chamber

    Anechoic chamber shielding for dynamometer
    Anechoic chamber shielding for EMI/ EMC dynamometer

     

    • The gas path waveguide takes into account the hydrogen pressure (5MPa). The entire gas path waveguide is integrally formed instead of welded. It avoids possible air leakage points and meets explosion-proof requirements. The design frequency range of the air wave guide is 9kHz~18GHz. The same shielding effectiveness is achieved as the anechoic chamber.

    Anechoic chamber shielding for EMI/ EMC dynamometer

     

    • In order to ensure that the power supply line between the filter and the LISN is well shielded, the anechoic chamber provides high-voltage connectors, including the raised floor under anechoic chamber. The high-voltage shielded cable is used from the high-voltage connector of the CP board to the LISN end.

    Anechoic chamber provides high-voltage connectors





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