Motor test bench for passenger and commercial vehicles


DynoEquip provides the electric vehicle motor test bench to meet the performance test of the motor and its controller system of the pure electric passenger vehicle and commercial vehicle. The motor test bench can automatically or manually test the normal performance, external characteristics, efficiency characteristics, NEDC and other tests of the motor, and can measure power, torque, speed, temperature and other parameters. Thereby, the motor performance parameters can be calculated and the correlation curve can be drawn.

 

Motor test bench for passenger vehicle

 

Passenger vehicle motor and commercial vehicle motor test bench can complete the stall torque and locked rotor current test, temperature rise test, continuous electric working characteristic test, motor maximum speed test, motor over speed test and feed operation characteristic test. At the same time, the test bench can feed the electricity generated during the test to the company’s power grid through the frequency conversion system.

The test bench is an AC dynamometer with four-quadrant operation capability and can work independently in the speed or torque control mode. The system is equipped with a bench test system, a control system, a test and measurement system, a calibration system, and a cooling water thermostat system.

 

Electric passenger vehicle motor test bench parameters (Dynamometer is air-cooled)

ModelRated power (kW)Rated torque (Nm)Rated speed (rpm)Max. speed (rpm)
AHD-012831,5001,8029,000
AHD-022507033,39412,000
AHD-033005705,02615,000
AHD-041604003,82016,000
AHD-052505004,77316,000
AHD-062605004,96617,000
AHD-072604004,77518,000
AHD-082505004,77320,000**

** Permanent magnet synchronous motor

 

Electric passenger vehicle motor test bench parameters (Dynamometer is water-cooled for low noise test environment)

ModelRated power (kW)Rated torque (Nm)Rated speed (rpm)Max. speed (rpm)
WHD-011734303,84015,000
WHD-022305004,39016,000

Passenger vehicle motor test bench

Water-cooled dynamometer for low noise test environment

 

Electric commercial vehicle motor test bench parameters

ModelRated power (kW)Rated torque (Nm)Rated speed (rpm)Max. speed (rpm)
ALD-015005,0009555,500
ALD-026504,5001,3806,000
ALD-035004,5001,0606,000
ALD-044403,5001,2007,500
ALD-056503,2301,9226,850
ALD-065502,9501,7809,000
ALD-073452,9001,1408,000

 

Commercial vehicle motor test bench

Electric commercial vehicle motor test bench

 

 

Motor test bench major test items

 

  • Motor with controller power and torque characteristics test
  • Motor with controller temperature rise test
  • Motor with controller blocking test
  • Motor controller control strategy development verification test
  • Motor driven controller maximum speed test
  • Motor with controller brake regenerative energy feedback test
  • Motor external characteristic test
  • Development and matching optimization test of motor and controller of the powertrain
  • Performance test and calibration test for motor and controller of the powertrain
  • Efficiency map measurement test
  • Accelerated response test
  • Torque response test
  • Steady-state cyclic loading endurance test

 

 

Motor test bench standard

 

  • GB/T 29307-2012 “The reliability test methods of drive motor system for electric vehicles”;
  • GBT 18488.1-2015 “The electrical machines and controllers for electric vehicles Part 1: General specification”;
  • GBT 18488.2-2015 “The electrical machines and controllers for electric vehicles Part 2: Test methods”;
  • GB/T 22669-2008 “Test procedures for three-phase permanent magnet synchronous machines”;
  • 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 18385-2005 “Electric vehicles – Power performance – Test method”.

 

 

Architecture of motor test bench for EV motors and controllers

 

The electric vehicle motor test bench for high speed EV motor controller test consists of the power zone, the test zone and the monitoring zone.

  1. The power zone is mainly composed of the test bench drive, the battery simulator for motor under test, an electric control cabinet, etc..
  2. The test area is mainly composed of AC dynamometer, measuring sensors, test bench cooling system, cooling system for EV motor under test, test bench, tooling and shock absorbing installation platform.
  3. The monitoring zone is mainly composed of the main control computer and electric control cabinet.

 

Power zone

  • The controller in the power zone of the high speed electric vehicle motor test bench is responsible for load simulation control and electric control.
  • When the load simulation control is performed, the electric energy is inverted by the controller and fed back to the power grid.
  • When the test bench needs to be electrically controlled, the controller takes power from the grid to achieve drive control.
  • The DC bidirectional power supply or battery simulator is responsible for powering the motor under test and can simulate the characteristics of different batteries.
  • When the motor under test is used as a generator, the DC bi-directional power supply can return the electric energy generated by the motor under test to the grid.
  • When an emergency situation occurs, the controller can quickly control the dynamometer to stop.

 

Test zone

  • The test zone of high-voltage electric vehicle motor test bench is used for the test of the test piece.
  • The test bench in the test area can be used for speed and torque control to simulate road loads. Load simulation methods include: constant torque control, road spectrum input, calculation of road spectrum, and user-defined load spectrum.
  • The DC bidirectional power supply is responsible for providing the required electrical energy to the motor under test.
  • The current, voltage and power of the motor under test can be measured through the power analyzer.
  • The test zone also includes the cooling system of the motor under test. It can detect the characteristic curve of the motor under test at different cooling temperatures. The cooling system has temperature and pressure alarm signals.
  • In addition, due to the high speed, the dynamometer is monitored in real time to prevent abnormal conditions and damage to the test bench or the motor under test.

 

Monitoring zone

  • The monitoring zone of the EV high speed motor test bench is composed of main control computer, fault monitoring computer, data acquisition system, sensor signal processing system, real-time controller and operation console.
  • The main control computer communicates with the real-time controller of the slave computer, and controls the driver in real time to realise load simulation.
  • The data acquisition system is responsible for the data acquisition of each sensor on the site. The data acquisition system transmits the data to the real-time controller of the slave computer in real time, and the main control computer reads the data from the real-time controller in real time.
  • The monitoring system saves, displays and performs various calculations on the data.
  • The fault monitoring computer monitors the vibration condition of the motor under test, the test bed bearing seat and the dynamometer in real time through the vibration sensor, analyzes and predicts the faults such as spectrum and relative order spectrum. Once the system is abnormal, the monitoring computer immediately informs.
  • The control computer takes corresponding measures to stop the test bench and the motor under test to prevent deep fault damage, and record all the data before stop. User can call the analysis.
  • The main control computer reserves two CAN bus interfaces to communicate with the motor controller under test. The system develops CAN communication protocol for the user, and user can customize the editing.

 

 

Motor test bench key technical item description

 

High speed dynamometer

The high speed dynamometer uses Germany high speed asynchronous motor (permanent magnet synchronous motor for 20,000 rpm or above), and the motor vibration in the complete test bench is less than 2mm/s for the full speed range. With independent frequency conversion control system, it can save energy and reduce consumption. The front and rear bearing sides of the dynamometer are designed with vibration monitoring. The three phase windings and bearings of the motor are designed with temperature monitoring.

 

High precision mechanical structure

The L-type tooling uses precision-machined thick steel plates, which are spliced by locating pins and bolts. Finally, on the large CNC machine tools, the positioning rabbets and end faces are positioned once to ensure the coaxiality.

The tooling and test stand bases are designed with positioning and adjustment mechanisms for ease of installation and subsequent repositioning for repositioning. The test bench base is subjected to two artificial aging treatments to eliminate the effects of residual stress.

The base of the test bench has the natural frequency adjustment function.

 

Motor test bench for electric vehicle

17000rpm motor test bench

 

Precision bearing support

The high speed bearing seat adopts high speed angular contact ball bearing, grease lubrication and natural cooling. The temperature rise of the bearing at the maximum speed does not exceed 35 °C, the design life is 20,000 hours of continuous operation, and the front and rear flanges of the bearing seat are designed with full dynamic balance. The end faces and radial runout on both sides of the bearing housing are better than 0.01mm.

The bearing housing is mounted by a base, and the non-flange mounting structure can improve the support rigidity of the bearing. The bearing housing is designed with bearing temperature monitoring and vibration monitoring to monitor the status of the housing in real time. The bearing housing designed by our company has been benchmarked with the same type of AVL. The vibration and temperature rise are not lower than the parameters of AVL.

 

 

Easy installation and operation

 

When the test motor is installed, it is required to ensure that its output shaft is coaxial with the shaft of the test bench, and the coaxiality is better than 0.02 mm, which requires that the transitional mounting flange of the test motor is aligned with the stop of the mounting positioning plate of the test bench. If the matching gap between rabbets is large, although the installation is convenient, the coaxiality cannot be guaranteed.

When the matching clearance is below 0.05mm, it is generally required that the two flanges can be well aligned and then pushed in gradually, so that the assembly is difficult. In the same way, it is more difficult to dismantle.

Two positioning guide pins are designed on the mounting plate of the test bench. The positioning guide pin and the locating pin hole of the transition flange have the matching gap more than 0.05 mm. The transition flange is first aligned with the positioning guide pin, inserted into the pin hole and then pushed forward to enter the positioning stop. The positioning flange of the transition flange is chamfered. Therefore, it is convenient to load the test motor.

Two ejector screws are designed on the transition flange for easy removal. In addition, the surface of the locating surface has the surface roughness of 1.6 which is very smooth and also facilitates assembly.

 

 

Motor test bench main mechanical structure

 

Test bench main structure

The mechanical structure of the test bench includes: test bench base, dynamometer mounting base, bearing support, test piece installation tooling, blockage mechanism and test piece connecting shaft.

 

Test bench base

The base of the test bench is welded, and the upper surface is welded with a 60 mm thick steel plate on the support. The surface of the steel plate is subjected to integral milling. After the welding is completed, a stress relief annealing is performed first, followed by roughing. After the roughing is completed, a second stress relief annealing is performed, and then finishing is performed to prevent the test bed from being deformed after long term use.

The flatness of the mounting surface on the base is not less than 0.05mm. The bottom of the base is equipped with a shock absorber. The floor structure provides the seismic performance required for high speed operation of the equipment. The flatness of the mounting surface on the base is less than or equal to 0.03 mm, and the surface roughness reaches Ra3.2.

After the base is completely welded, the base is subjected to stress relief annealing, and the upper surface and the bottom mounting surface are processed. Anti-rust paint and top coat are applied to the non-installation surface of the base.

The base of the test bench is installed on the cast iron platform. The air spring shock absorbers are installed between the base of the test stand and the cast iron platform for shock absorption. The natural frequency of the shock absorber is lower than 5 Hz, and the damping efficiency reaches 98%. The vibration within the range of no-load full speed does not exceed 2 mm/s.

Motor test bench base

Test piece tooling

The tooling of the test piece is made of steel plate bolt splicing structure. The tooling of the test piece is made up of four pieces of finished steel plate, which are connected by bolts. The thickness of the steel plate is not less than 60mm. Since the accuracy of the installation tooling of the test piece directly affects the alignment accuracy of the test piece, the accuracy of the installation tool is required to be high, and deformation cannot be generated at the same time. If a welded structure is used, it is difficult to ensure that deformation will not occur under high frequency vibration.

In order to improve the coaxiality of the shafting system, after the L-shaped tooling is mounted on the base of the test bench, the positioning and positioning end faces of the test motor mounting plate are machined based on the output shaft and the flange end face supported by the bearing. In this way, the positioning fixture can ensure the coaxiality of the shafting system is better than 0.02mm. The bottom of the L-shaped mounting tool is designed with positioning guide keys. There is a keyway for positioning processing on the base of the test bench, and the positioning guide key is also designed on the mounting base of the dynamometer.

The positioning keys of the L-type tooling and the motor mounting base are matched with the keyway on the base of the test bench. Therefore, it can be ensured that after the L-shaped tooling is once positioned and processed on the base of the test bench, even if the tooling is removed, the re-installation can be ensured without re-adjustment.

 

Motor test bench mounting plate

Vertical mounting plate and bottom mounting plate

 

Motor test bench climatic chamber installation plate

Reserved climatic chamber installation plate

 

The reserved climatic chamber mounting structure allows the mounting plate of the climatic chamber to be placed in the middle of the four columns. The side panel of the climatic chamber is connected to the climatic chamber host by a quick snap and sealed. When installing the test piece, the climatic chamber is just simply moved backwards. Through this structure, the heat insulation effect of the climatic chamber can be well realized, because the mounting plate of the motor does not need to be specially made of the temperature insulation plate.

The positioning end surface of the test motor mounting plate is subjected to high frequency quenching to improve the surface hardness and improve the wear resistance. The vibration sensors are installed in the X/Y/Z direction of the L-type mounting tool to monitor the vibration state of the motor under test in real time.

 

Blocking mechanism

The blocking mechanism adopts mechanical blocking. It consists of blocking flange, flange fixing bracket and blocking location detection sensor.

 

Motor test bench blocking mechanism

 

When the stall test is not carried out, the blocking flange is fixed to the bearing housing by bolts and is isolated from the shaft. When the stall test is required, the blocking flange is removed from the bearing housing, moved to the pedestal of the input flange of the bearing housing, and fixed by bolts. 20 holes are evenly distributed on the blocking flange, and the fixing pins on both sides of the blocking flange fixing seat can be inserted into the blocking flange hole to perform the blocking test.

In addition, a proximity switch is mounted on both the fixed base and the bearing housing for detecting the position of the stalling flange and preventing the system from moving.

 

Bearing support

The bearing seat acts as an intermediate support for connecting the motor under test and the dynamometer to isolate the motor and dynamometer under test. If the motor under test is misaligned or malfunctions, the bearing seat can act as the buffer. However, due to the long term reliable operation of the bearing housing at high speed, strict requirements are imposed on the bearings.

At the same time, in order to prevent shafting resonance, the structure of the bearing housing needs to undergo finite element modal analysis to optimize the structure. In order to improve the dynamic balance accuracy and reduce the vibration of the shaft system, in addition to the dynamic balance of each rotating member, the shaft system is dynamically balanced on the field after the shaft system is installed. The flanges on both sides of the bearing support are designed with the full dynamic balance to facilitate on-site balancing.

 

 

Dynamometer system

 

Dynamometer

The dynamometer includes an encoder and temperature sensors. The encoder is HTL 1024. The temperature sensors monitor the bearings and the windings respectively. The bearings adopts PT100 and the windings adopts PT100 plus KTY84. Vibration sensors are installed at the front and rear ends of the dynamometer to monitor the vibration state of the dynamometer in real time.

 

Dynamometer driver

The dynamometer drive adopts high end frequency converter, and the inverter adopts Ethernet communication which is controlled by the host computer in real time. Since the dynamometer needs to simulate road load and dynamic test, the controller and the host computer need to have very fast response speed.

 

 

The measurement and control system

 

The measurement and control system consists of host computer monitoring system, data acquisition system, sensor measurement system, frequency converter control system, test bench auxiliary equipment control system, safety monitoring system and early failure warning system. The measurement and control system uses a real time bus as the main communication network and CAN bus that communicates with the device under test. The host computer monitoring system communicates with the data acquisition system and the inverter control system through real time bus, dynamically controls the motor in real time, collects the data of each sensor at high speed, and analyzes and processes the data.

The slave computer controller communicates with each auxiliary test system, controls the auxiliary test system and simultaneously collects the sensor data of each safety monitoring such as: motor temperature, bearing temperature, coolant temperature, cooling pressure, etc.. The DI/DO interfaces are controlled, for example, the system issues an emergency stop command, and the slave computer controller immediately outputs the corresponding DO signal to cut off the power of the corresponding system to ensure system safety.

Since this motor test is the kind of high speed rotary test bench and durability test bench, it is necessary to perform strict fault monitoring, fault warning and rapid fail-safe shutoff of the test bench and the test piece. An independent warning system for mechanical rotating parts is designed in this system. The early warning system is based on a vibration sensor installed on the motor, dynamometer, bearing housing, etc., and can promptly indicate early minor faults of the mechanical system. It is also possible to sense sudden changes in the mechanical system.

The main control system also processes the sensor data of each subsystem and performs alarm and shutdown processing for the state exceeding the set safety value.

The test bench uses an independent controller-based architecture that dramatically increases system responsiveness. The architecture improves the system’s speed and reduces system risk in the event of fault.

 


 

Motor test bench, small motor testing systems

 

The needs of test rig for small motor testing: Development of new drive systems for electric and high efficiency engines requires test technology that can meet the most stringent standards of serviceability and flexibility. In modern vehicles there are many electric motor. Traditionally these were limited to windshield wiper, window lift, fuel pump, sunroof, electric seat, air compressors, and lift gate or trunk latch release. With the advent of electric cars, coolant pump and refrigerant compressors have been added to the list.

Additionally, electric motor has infiltrated safety sensitive applications such as electronic throttle control, electric steering, electric door opening, cam phaser and traction motor. While all vehicle components must undergo rigorous testing, safety items must undergo more stringent durability and end-of-line testing. A number of methods can be used to physically load the motors, however, motor test rig, small motor testing systems are preferred for their high speed, flexibility and ability to back drive the test item while at high speed.

While the small motor testing systems are applying loads and temperature cycling, many data parameters are logged, some at high speed. Typical attributes are motor voltage, current, temperature, torque and speed. One area of primary interest is motor cogging (torque ripple), particularly at low speeds. Audible noise and vibration may also be a concern and sensors and data acquisition may be included for this as well.

There are many reasons to perform motor testing. Durability testing ensures that the motor will last a calculated length of time that simulates an extended life of an automobile. Performance testing is required to benchmark the motor’s performance at various temperatures and loads. Regardless of the testing type, various loads are applied while thermally cycling the motors.

Simpler motor is typically subjected to different loads but kept at relatively constant speed, with just the input voltage changed to simulate high and low battery conditions. Motor in applications such as electric steering and traction motor are subjected to very different torque and speeds.

 

Small motor test bench

 

ModelRated power (kW)Rated torque (Nm)Rated speed (rpm)Max. speed (rpm)
SI-A11338.03,26718,000
SI-W12058.03,29318,000
SI-W28.529.02,79919,000
SI-A26.015.03,82020,000
SI-A34.88.25,59024,000
SI-A47.05.113,10624,000
SI-W31121.05,00224,000
SA-W12522.110,80224,000
SA-W24078.84,84724,000
SA-W39.55.018,14330,000
SA-W4187.323,64236,000
SA-W55.54.611,34340,000
SA-W62.51.121,70250,000

 

Motor test rig, small motor testing systems technology

 

The scope of motor test rig, small motor testing systems comprise mechanical components such as drive test setups with torque sensor, dynamometer with torque and speed measurement and manual or external control, as well as computer controlled complete solutions for the analysis and documentation of electrical machinery.

By means of an integrated power analyzer, computer controlled dynamometers can be realized with up to 12-channel current and voltage measurement, so that a separate efficiency specification of motor and converter can be effected even for converter fed drive systems.

 

Motor test rig, small motor testing systems control software

 

The motor test rig, small motor testing systems control software serves for parameter assignment of the test stand including the converter for the active brake and the test sequences of the test system, so that an optimum of profitability and precision is achieved.

  • Various test modules
  • Manual operation
  • Motor characteristics curve (dynamic, stepwise)
  • Locked motor torque test
  • Friction loss measurement
  • Warm-up operation
  • Static operation
  • No load
  • Families of characteristics curve
  • Harmonic values
  • Load cycles and cyclical load
  • Step changes in load with transient data collection
  • Load and start-up characteristics
  • Recorder
  • Customer specific applications
  • Laboratory report

 

Environmental chamber as option

 

Electric motor laboratory and performance must include features to control the application of stimuli, the most difficult usually being temperature cycling. Many of the systems are designed to be wheeled into an environmental chamber, and if needed shield any of the sensitive test rig components from temperature extremes or humidity.

If the system is very intricate it may be necessary to replace the environmental chamber door with part of the test apparatus so that the small motor testing systems can be pushed on wheels and mated to the chamber. It is usually best not to build the test fixture rig into the chamber for serviceability reasons, but this is sometimes required for cleanliness reasons if the electric motor is part of a hydraulic pump system. External thermal generator systems are also sometimes used and a small custom thermal enclosure is built around the test item.





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