Ready for future mobility

FEV´s e-motor test beds

9. September 2017 | Engineering Service

Electromobility is constantly increasing in importance, and is currently a significant part of daily challenges. Hybrid and electric vehicles continue to represent a minority, but the number of research projects is increasing rapidly. FEV guides its customers on the path to electric mobility and offers solutions for multifaceted and complex challenges.

New Drives, New Challenges

In addition to various hybrid concepts, the focus is on fully electric drives. As a development service provider, FEV manufactures and distributes test bed components and complete test beds with which drive components can be tested.

Components such as high capacity energy storage devices (traction batteries), inverters and electric motors are relatively new and have no application in conventional drive concepts. In addition to the quality of individual components, their combined application in vehicles must also be ensured. Manufacturers and suppliers face a wide range of requirements. For example, both hybrid solutions and purely electric drives require the most modern, high-capacity energy storage devices. The currents and voltages employed in these reach up to 1,500 amperes or 1,000 volts, respectively. Consequently, test beds must be oriented according to the corresponding safety conditions, and employees must be trained.

Component Tests

The testing of an electric motor for mobile application in a vehicle should absolutely be compared to that for a combustion engine. However, the individual components such as inverters and batteries are also tested separately. Special battery test rigs enable tests of battery cells, battery packs, and complete traction batteries. In order to test the lifespan of the batteries, for example, these are subjected to different charging and discharging cycles in climatic chambers.
Decisive differences from combustion engines can be found in the use of current as the drive power and in the far higher rotational speeds of electric motors. Two years ago, the maximum rotational speed was limited to about 15,000 rpm. FEV is currently delivering E-Motor test rigs with 20,000 rpm speed capability. Future test beds will be capable of up to 30,000 rpm.


System Tests

The components are also tested together, and as closely to reality as possible, in the context of a system test. In this context, it is necessary to consider both hybrid drives, meaning the integration of electrical components into the powertrain, and purely electric drive concepts. In addition to traditional drive concepts, there is now a so-called “E-axis” coming into play. This involves a highly integrated electric drive unit, arising from the combination of an electric motor, transmission, inverter and control unit.

The inspection of the E-axis is carried out by connecting right and left dynamometers in order to emulate road stress.

Additional challenges arise from the testing requirements, the design, and the electrical system components. In addition to the familiar driver-vehicle simulation, a simulation of climatic conditions is also carried out. This involves trials in temperatures ranging from -40°C to 120°C. Comprehensive conditioning systems for the test subject’s cooling media, high-precision measurements of rotational speed, torque, voltage and current are only a few of the new challenges FEV meets in this area in order to be able to offer expert solutions.

The Service Range of FEV

FEV operates, plans and implements electromobility test beds for internal and external customers. This involves the use of FEV dynamometers and conditioning systems as well as tailor-made solutions for customer-specific requirements. The MORPHEE automation system offers a high degree of flexibility and simple configuration for various test bench types. In addition, FEV not only supplies the interfaces necessary for the integration of power analyzers (measurement of voltage and currents of up to 1,500 A and 1,000 V), but also provides its customers with advice on the configuration of test rigs with regard to safety and machinery directives for the achievement of CE conformity.

Battery - E-Motor test beds

FEV operates, plans and implements electromobility test beds for internal and external customers.