Schabmüller GmbH is the market leader in producing electric motors for mobile machinery. Together with HBM, Schabmüller has developed a new test-bench concept for a new type of drive. It combines the advantages of precise and cycle-accurate testing and measuring equipment with those of convenient test-bench development. This concept facilitates easily integrating sensors into the measurement system and controlling tests based on acquired data. Thanks to the formula database, which also provides formulas for real-time DSP calculation, the motor developer can quickly and easily create individual calculations – for customizable measuring and testing tasks.Electric machines are the drives of today and the future. While the automotive industry still struggles with this transition, electric machines have been the standard in vehicles such as forklift trucks for over 50 years. Moreover, the requirements for motor performance and efficiency are continually rising. Hence, electric motor manufacturers work continuously to develop new drives. Simultaneously, new test-bench concepts are in demand to test these new motors with the required accuracy. The challenge is to obtain reliable results while precisely controlling test processes. Schabmüller GmbH, the world’s largest independent manufacturer of electric motors for battery-powered vehicles, also applies these requirements to its own test equipment. Together with HBM, the electric motor producer has developed a test-bench concept that enables measured data to be acquired and evaluated in line with these requirements. Schabmüller designs electric drives for forklift trucks, hybrid trucks and buses, as well as for construction and agricultural machinery. Schabmüller developers rely on HBM's extensive measurement technology in their new synchronous motor test bench, specifically the Genesis HighSpeed data acquisition system and the Perception software program. A software program developed using National Instruments’ LabVIEW* development environment is deployed for automating and controlling the test bench. "The Genesis HighSpeed measurement system is exceptionally easy to work with and all processes run in parallel and in real time. This makes the development processes of our test bench software much easier and less complex," explains Dr. Martin Hafner, Manager of Technology Development for Permanent Magnet Synchronous Machines at Schabmüller. "Personnel expenses are considerably lower with Genesis HighSpeed in comparison to a measurement system based on National Instruments components alone."
"We chose the combination of Genesis HighSpeed and Perception software, as well as the LabVIEW development environment because Perception and LabVIEW are very easy to connect with an interface,"according to Stefan Lauck, development engineer at Schabmüller. "Thanks to the Perception sensor database, we can also integrate a wide range of different sensors for current, voltage and torque into the measuring system quite easily, simply by plug-and-play, like inserting a USB device in a computer. Integrating vibration sensors as part of electrical measurement equipment is possible without any problems. That saves us time and resources in setting up the test bench." The Schabmüller test bench is used for various measurement tasks to reliably determine the short-term or continuous power and energy conversion efficiency of synchronous machines, or to identify their service life and component reliability. Schabmüller experts measure rotational speed and torque, generate efficiency maps, and, based on this measured data, determine longitudinal and transverse inductances. Additionally, Schabmüller implements service life experiments under maximum mechanical stress. Long-term thermal experiments also determine how various long-term and interval loading patterns affect the motor function. "The electric motors have to achieve a service life of at least 50,000 hours," explains Stefan Lauck.
"We can also create our own formulas for the calculations in Perception and save them in the formula database. These formulas can be used in both post-process and real-time calculations in the DSPs, without any programming of the respective computer architecture.”Perception communicates with the LabVIEW software via a freely programmable software interface. The LabVIEW software is responsible for controlling and automating the test-bench processes. Based on real-time computing results, it controls the load and test specimen machines’ inverters. "The measured data can be processed for cycle-synchronous individual values. Then only the relevant cycle-synchronous computing results are used for control and automation of the test processes. For example, the RMS values of current and voltage or the torque values," says Stefan Lauck. "Since, if need be, the raw data will still be saved, we can also use it for more extensive post-process analyses." In addition to the cycle-synchronous individual values, continuously measured data can also be linked in the Perception formula database and processed in real time. No programming knowledge is required for this either.