Gantner Instruments GmbH, Montafonerstr. 4, A-6780 Schruns, Austria
Standalone E-drive testing in 3 simple steps
Tips & Trends | 3 minutes Reading Time |

Standalone E-drive testing in 3 simple steps

Automobiles have a variety of electrically operated drives. Be it the sunroof, the window lifter, the seat adjustment or the trunk lid, everywhere you look, you’ll find electric motors that provide us comfort in our cars.

For the testing of these e-drives, we implemented the data acquisition solution and evaluation for a large German automotive supplier. Power consumption and speed are relevant to evaluating the efficiency of electromechanical systems. Since the motors are permanently installed into vehicle body parts, often only the electrical current and voltage signals are all that’s available for quality testing.

Using the Current Signal to Determine Motor Speed

In a classic DC motor, the mechanical commutator leads to a brief drop in the current curve when poles are reversed. Depending on the design and number of poles of the motor, the quantity of current dips corresponds to one revolution. This model is also reflected in the current curve of brushless motors with electronic commutation.

Figure 1 demonstrates the current curve of a motor over time. The current pictured here was measured with a Q.bloxx XL A107 I/O module and a shunt. The current drops visible in this example occur during commutation at intervals of 8.4 ms.

Stromverlauf
Fig. 2: Spectrum of the current characteristic curve

Accordingly, the spectrum of the current curve (Figure 2) shows its maximum occurs at 119 Hz. Assuming 3 commutations per revolution, this corresponds to a speed of 2380 revolutions per minute.

The spectrum can be performed both online and offline by Q.series X controllers. In this way, the engine speed can be determined continuously and live on the test bench using the current signal. The necessary configuration is performed in just a few steps.

Quick-and-Easy Configuration on the Test Bench

The FFT function of the Q.series X controller offers, among other things, the possibility to evaluate the maximum of a spectrum within a selected frequency band by magnitude and frequency. The frequency of the maximum corresponds to the fundamental wave and is divided by the number of poles and multiplied by 60 to give the speed in revolutions per minute (rpm). Also, the current is used to detect whether the motor is in operation and whether the electrical power can be calculated.

Fig. 3: Hardware configuration with GI.bench

This edge computing allows the motor speed to be determined without a separate computer.

Depending on the test bench configuration, data can now be transferred to the system control, e.g., via EtherCAT or visualized within GI.bench on the test bench PC or over the local network.

Simply Powerful Visualization

With GI.bench, you can create custom dashboards for visualization. Figure 4 shows the speed and power in the upper chart. When the motor is loaded, the speed decreases (green curve), while the power consumed increases (grey curve). Also, the current spectrum (blue), the current trace (red), and the parameters (table) are displayed numerically in this interface.

Fig. 4: Visualization with GI.bench

For references, demo programs and questions you can always contact us at info@gantner-instruments.com.

More articles

News & Events

3 ways advanced DAQ solutions help the aviation industry transition to a sustainable future

By 2050 we need to become a carbon-neutral society, and the aviation sector needs to contribute. While flying less can help reduce emissions, we have options for cleaner air travel. For one, we could power our flight with electricity or hydrogen, which are no longer ideas in some futuristic science fiction novel. Rather, they are on the brink of generating a shift in aviation technology.

Read more...
Tips & Trends

How to get insight into your measurement data with online dashboards in 3 steps

Data empowers engineers across sectors to improve their processes, initiatives, and innovations using the power of insight. The ability to monitor and respond to data from an increasing number of sensors can seem like a minefield. Data dashboards have evolved as one of the essential tools for professional engineers to get a grip on their measurement data.

Read more...
News & Events

Gantner Instruments Helps Flood Victims in the Philippines

Yet another terrible natural disaster has left its mark. In the Philippines, the typhoon Hayian has cost the lives of countless people. Gantner Instruments made a donation to support reconstruction.

Read more...
News & Events

Webinar – Crate.io + Gantner Instruments: Real-time energy grid control based on big data

With the increase in renewable energy sources, the challenge for electric grid operators to keep grid frequencies stable has become even more significant. Constant data collection is essential for modern control technology and makes it possible to execute controls more quickly, whereby the use of smart grids can be further optimized.

Read more...