A Driver of Innovation for Electric Motors with a Highly Efficient Test Bench

A modern test bench concept for innovative electric motors

As a driver of innovation in the industry, Schabmüller now also offers its customers permanent magnet synchronous electric motors. This new type of drive, without any changes to the cooling concept, produces just as much power as comparable asynchronous motors while requiring considerably less space. Optimizing or revising the cooling concept enables this effect to be disproportionately increased. To achieve this, synchronous motors must meet high requirements, be powerful and energy-efficient, and have a high energy conversion efficiency to optimally use the supplied energy. To ensure precise tests for the new electric drives, Schabmüller worked with HBM experts to optimize the test bench’s entire measurement chain.

"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.

An optimum system for extremely fast real-time tests

To securely and reliably determine all measured data, the test bench’s individual components must work together perfectly. The sensors acquire measurement signals such as current, voltage, temperature and torque and forward them to the data acquisition system. The Genesis HighSpeed GEN7tA data acquisition system is used on the Schabmüller test bench along with GN610B acquisition cards. The DSPs, digital signal processors on the cards, process the measured data and calculate the initial results in real-time. The calculated measurement results are forwarded to LabVIEW for analysis – at up to 1000 times per second thanks to the EtherCAT connection. In parallel, HBM’s Perception software also saves all the acquired raw data. "Measured data and real-time computing results are acquired and forwarded simultaneously and with the same time stamp. That's an enormous advantage for analysis," emphasizes 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.

Easy sensor integration and channel synchronization

"The combination of LabVIEW and HBM's Perception software really does offer us many advantages," says Stefan Lauck. "Genesis HighSpeed synchronously records measured data of sensors and allows for sample rates of up to 2 MS/s on up to 51 power channels. It automatically synchronizes the sample rates of the different channels and input cards. This considerably reduces users’ overhead. We were also able to make optimum use of LabVIEW advantages, such as the TDMS data format, to rapidly save large amounts of data. This also facilitates the subsequent data analysis using a wide range of available software products."

Schabmüller’s developers received customized support from HBM’s Perception experts as they integrated the data acquisition system into the test bench. According to Stefan Lauck: "Perception is an efficient software program that acquires data reliably. Thanks to the introductory training from HBM, we quickly became proficient. And because Perception is so easy to work with, we are able to define measurement sequences for our specific purposes."

* LabVIEW is a trademark of National Instruments. Neither HBM, nor any software programs or other goods or services offered by HBM, are affiliated with, endorsed by, or sponsored by National Instruments.

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