EV motor controller EMC test with loading

 

With the rapid development of hybrid and electric vehicles, especially the rapid popularity of electric vehicles, electromagnetic compatibility has received more and more attention. As the major component of electric vehicles, electric drive system (electric powertrain) has high voltage, large current, complex structure and diverse couplings, which is one of the most important sources of interference for electric vehicles.

For this reason, the through-the-wall-type EV motor controller EMC test 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.

The EV motor controller EMC test in anechoic chamber is specially designed to meet the requirements of CISPR25, GB/T18655, GB/T36282, GB/T18387 and other standards, and meets the test bench EMC testing of battery, electric motor, motor controller and electric powertrain. The test bench can complete the test of conducted emission, radiation emission and radiation immunity, and large current injection of auto parts products (including high voltage components of electric vehicles such as automobile motor controller, electric motor and power battery).

Motor and controller CISPR25 anechoic chamber, control room, power amplifier room shielding effectiveness according to the standard EN50147-1 or GB/T12190 latest standards (frequency range 10KHz ~ 18GHz). The specific test frequency is determined according to the test frequency of the third party testing organization, and the following indicators are met:

 

FrequencyAttenuationField source
10kHz≥80 dBMagnetic field
10kHz≥100 dBElectric field
100kHz≥100 dBMagnetic field
100kHz≥110 dBElectric field
1MHz≥100 dBMagnetic field
1MHz≥110 dBElectric field
100MHz≥110 dBElectric field
400MHz≥110 dBPlane wave
1GHz≥100dBPlane wave
10GHz≥100dBPlane wave
18GHz≥100 dBPlane wave

 

In the absence of device under test, monitoring system, lamp and filter power, the background noise level in the range of 9 kHz to 6 GHz should be at least 10dB lower than the limit of class 5 (PK, QP, AV) specified in the latest version of CISPR25. At the same time, it is at least 6dB lower than the GJB151B RE102 limit.

 

Test objects

The electric drive, electric powertrain EMC test bench is suitable for EMC test projects for automotive component products, including motors, motor controllers, batteries, and high-voltage components for new energy vehicles such as pure electric drives and hybrid drive assemblies.

 

Reference parameters of the test object

  • Motor input torque: ± (0 ~ 500) Nm
  • Motor input speed range: 0 ~ 20,000 rpm
  • Electric powertrain speed ratio range: 0.68 ~ 18.0
  • Electric powertrain drive form: transverse, vertical

 





EV motor controller EMC test bench structure

 

1. Anechoic chamber

According to the requirements of CISPR25, the long-line method is used to test the chamber performance, and the test value is compared with the reference value specified in CISPR25-2016. The deviation of the frequency point above 90% from the reference value is within ±6 dB.

 

2. Control room, power amplifier room

The frequency range is based on the latest editions of EN 50147-1, GB/T 12190 and MIL-STD 285.

 

3. Dynamometer system

The dynamometer system is designed to test the EMC performance of the electric drive system under the condition of the whole vehicle. It is required to realize the simulation condition and cannot affect the EMC test.

 

4. Connection system of motor under test

  • In order to optimize the entire powertrain, the dynamometer shaft and the motor under test will be considered together. The mechanical connection of the shaft system is safe and reliable, which can protect the motor under test and reduce the risk of broken shaft.
  • The transmission shaft is the non-magnetic, non-conductive composite material, and its mechanical connection is safe and reliable, and has a safety protection design to prevent high-speed rotating parts from flying out and injuring people.
  • The shaft connection system should take measures to avoid static electricity and prevent the EMI background from exceeding the standard.
  • The shaft connection system takes effective measures to prevent electromagnetic signals from entering the anechoic chamber inside.

 

5. Motor test system equipment foundation

  • The dynamometer and the motor under test are the complete bottom support structure with low vibration, which can meet the test requirements of the high speed and high torque of the motor under test and prevent the noise interference caused by the running speed to the greatest extent.
  • The dynamometer and the base of motor under test in the anechoic chamber are integrally installed to avoid the internal or external height difference or horizontal offset caused by the long-term use of foundation settlement. The impact of vibration is fully taken into account during the design of iron plate, motor under test and adjustment system.

 

6. Battery simulator

It is used to supply high voltage DC power to the motor under test system. The battery simulator control and monitoring functions are integrated with the dynamometer system and are collectively acquired and controlled by the dynamometer system. During the test emergency stop of the dynamometer system, the battery simulator and the entire system can be safely parked. The dynamometer and battery simulator can be operated separately. The battery simulator can perform charging and discharging tests on the battery pack under different conditions.

 

7. Cooling system

The temperature and flow control of the cooling system is integrated into the dynamometer control system to cool the inverter and the motor under test. The cooling system piping enters the anechoic chamber through the corresponding waveguide, and no leakage is allowed to ensure stable operation.

 

8. Air conditioning duct system

  • Air conditioning ventilation system design includes parameters such as ventilation pressure and pipeline distribution.
  • The anechoic chamber shielded room operates in the temperature and humidity controlled environment.
  • There is no condensation in the chamber due to temperature differences.

 

9. Supporting tools

The electric drive, electric powertrain EMC test bench fully consider all the external power distribution from the anechoic chamber, control room, power amplifier room related filter front end to the main power distribution cabinet and battery simulator; the frequency conversion cabinet to the main power distribution cabinet; and the cable tray connection.

 

 



EV motor controller EMC test bench test projects

 

1. EV motor controller EMC test range: emission type

 

Low voltage conducted emission

  • Test method: voltage method, current method
  • Test range: 150kHz~108MHz
  • Reference standard: CISPR25-2016,GB/T 18655-2018

 

High voltage direct current conducted emission

  • Test method: voltage method, current method
  • Test range: 150kHz~108MHz
  • Reference standard: CISPR25-2016,GB/T 18655-2018

 

Low voltage transient transmission emission

  • Test method: Fast pulse, slow pulse
  • Test range: Waveform according to standard
  • Reference standard: ISO 7637-2,GB/T 21437.2

 

Radiation emission

  • Test method: ALSE method
  • Test range: 9kHz~6GHz
  • Reference standard: CISPR25-2016,GB/T 18655-2018,GB/T 36282-2018,TL-81000

 

Electromagnetic field intensity emission of components

  • Test method: Electric field, magnetic field
  • Test range: 150kHz~30MHz
  • Reference standard: GB/T18387-2017,SAE J551-5-2012

 

Low frequency magnetic field emission

  • Test method: Magnetic field
  • Test range: 20Hz~150kHz
  • Reference standard: GJB 151B-2016

 

High and low pressure combination

  • Test range: 150kHz~108MHz
  • Reference standard: CISPR25-2016,GB/T 18655-2018

 

2. EV motor controller EMC test range: anti-interference type

 

Radiation anti-interference BCI method

  • Test method: BCI method
  • Test range: 100kHz~400MHz
  • Reference standard: ISO11452.4-2005,GB/T 33014.2-2016,TL-81000

 

Radiation anti-interference ALSE method

  • Test method: ALSE method
  • Test range: 200MHz~6GHz
  • Reference standard: ISO11452.2-2004,GB/T33014.4-2016,TL-81000

 

Power cable transient conduction anti-interference

  • Test range: Waveform according to standard
  • Reference standard: ISO 7637-2,GB/T 21437.2-2008,GB/T 36282-2018

 

Control and signal transient conduction anti-interference

  • Test range: Waveform according to standard
  • Reference standard: ISO 7637-3,GB/T 21437.3-2012

 

Electrostatic discharge

  • Test method: No power
  • Test range: Waveform according to standard
  • Reference standard: GB/T19951-2005,GB/T 36282-2018



Normative standard of EV motor controller EMC test bench

 

1. Anechoic chamber normative standard

 

  • EN 50147-1:1996 《Anechoic chambers — Part 1: Shield attenuation measurement》
  • GB/T 12190-2006 《Method for measuring the shielding effectiveness of electromagnetic shielding enclosures》
  • CISPR 25:Ed.4 《Vehicles, boats and internal combustion engines – Radio disturbance characteristics – Limits and methods of measurement for the protection of on-board receivers》
  • GJB 151B 《Military equipment and subsystems – Electromagnetic emission and sensitivity requirements and measurements》
  • MIL-STD-461G 《Requirements for the control of electromagnetic interference characteristics of subsystems and equipment》
  • GB/T 17626 《Electromagnetic compatibility – Testing and measurement techniques》

 

2. Dynamometer normative standard

 

  • GB/T 12668.2-2002,IEC 61800-2:1998 《Adjustable speed electrical power drive systems–Part 2: General requirements》
  • QC/T 534-2005 《Vehicle drive axle bench evaluation》
  • GB/T 18488.1 《Drive motor system for electric vehicles. Part 1: Specification》
  • GB/T 755-2008 《Rotating electrical machines – Rating and performance》
  • JB/T 1093-1983 《Basic test method for traction electrical machines》
  • JB/T 7584.2-1994 《Motor dynamometer – Induction dynamometer》
  • JJG 653-2003 《Verification regulation of equipment of power measuring》
  • GB/T 22669-2008 《Test procedures for three-phase permanent magnet synchronous machines》




Background of EV motor controller EMC test bench

 

Comparing with traditional vehicle using fuel as power source with drive and control system, electric vehicle, hybrid vehicle and fuel cell vehicle have more amount of power electronic devices including electrical components with high voltage and power and electronic control units with high electromagnetic sensitivity. Those parts can trigger particularly prominent electromagnetic compatibility (EMC) problem which should be paid attention to.

EV or PHEV power inverter, electric motor drive system and other key components use the pulse-width modulation (PWM) technology which will produce large number of harmonic interference signals. Not only the vehicle wireless equipment will be affected, but also the reliability of the electronic control units such as antilock brake system (ABS), supplemental restraint system (SRS) and electronic braking system (EBS) through the conduction or radiation channels. This issue is directly related to the safety of the vehicle.

Therefore, hybrid or electric vehicle EMC issues are very critical. With the further development on fuel cell, hybrid or electric vehicle and increasingly stringent regulatory requirements, the electric powertrain EMC test for high voltage components should be taken.

The major components of high voltage system in hybrid or electric vehicles are battery (can be up to 1000Vdc), inverter (DC/AC, DC/DC), and electric motor (AC or DC). The noise level in high voltage system can be very high. This noise can be coupled to the low voltage system. The electric powertrain EMC test for high voltage component in hybrid, electric or fuel cell vehicles are needed.

The anechoic chamber with the load simulator (dynamometer) setup can support different drive modes under high voltage operation with additional instruments such as energy system (battery simulator or DC power supply).

 

Common problems in high voltage system

 

  • High DC voltage is converted into 3-phase AC voltage with variable frequency
  • This conversion process causes with high electro-magnetic field strengths over a broad frequency range
  • The noise is particularly high in the low frequency (LF), medium frequency (MF) and high frequency (HF) bands and can also disturb the very high frequency (VHF) bands
  • Due to higher voltages, the noise level may increase up to 50 times comparing to conventional vehicle electronics

 

Common problems of automotive component testing on HV system

 

  • Interference level on the traction leads
  • Interference level on a motor phase line
  • Pulses in the high-voltage traction network and phase network
  • Coupling between high voltage and low voltage including sterical electro-magnetic coupling (components inside the same housing) and functional coupling (data buses, functional links, power supply 12V)

 

Technical challenges on EV motor controller EMC test

 

  • For the normal 12V or 24V components, there are many EMC standards with clear technical guideline to follows, such as CISPR25, ISO11452, OEM standards .. etc
  • These existing standards or guidelines are still applicable for testing HV components for examples battery, inverter, motor but not enough.
  • High current and voltage may cause the following difficulties:
    • Large and expensive components (coils, capacitors)
    • Extensive weight
    • Requirement of larger space
    • Safety
  • Test setup
    • Whole setup is done in shielded anechoic chamber
    • Shall be able to simulate the operation of EUT under different drive mode: Drive, Brake, Recuperation
    • Variable speed test
    • Mechanical stability of motor oscillations
    • Cooling system for test sample

 

CISPR 25 standard for test setup in anechoic chamber

 

The guideline in existing CISPR25 standard is not good enough for testing HV components. We propose the best suitable test setup in anechoic chamber with HV inverter and motor.

 





Major technical considerations of EV motor controller EMC test bench

 

1. Consideration of drive shaft

 

  • The system can effectively isolate the electromagnetic radiation from the dynamometer and shield the conduction harassment of the transmission system
  • Although the drive shaft penetrates the shield of anechoic chamber, the shielding effect of the anechoic chamber is not greatly affected
  • Although the connection between the dynamometer and the test motor drive shaft is very long, the vibration during high-speed rotation will be effectively controlled
  • During testing, the static electricity generated by high-speed rotation of the drive shaft and bearing friction can be well controlled and will not affect the EMI test results

 

2. Consideration of safety

 

The system will effectively control the test environment with many human and test hazards in high voltage test motor (EUT) including: high-speed rotating and drive components, high voltage (1000V DC), cut-off voltage, radiation source, mechanical vibration, electronic load from high temperature, coolant, electric field strength of EMC test, the use of lithium batteries possibly catching fire or explosion.

 

3. Consideration of cooling system

 

  • To meet the actual needs, the cooling system needs to cool down the e-motor, e-motor controller and battery simulator system with cooling water.
  • The cooling water consumption is designed based on system heat dissipation, temperature requirement, water flow and pressure requirement; cooling water temperature, flow and pressure display and control; pipe temperature and pressure; pipe joints inside anechoic chamber, etc.





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