Electric drives – better testing: increased efficiency


The future belongs to electric drives. An electric drivetrain, which includes an inverter and electric motor, must become increasingly efficient. However, the standard methods for performance testing and efficiency measurement of electric drives provide inadequate results.


With the HBM eDrive testing solution, electric machines and drives can be efficiently analysed. HBM’s innovative eDrive testing solution enables synchronous, dynamic and continuous acquisition of mechanical and electrical signals, as well as live analysis. It is composed of the HBM T12 torque transducer; HBM GEN3i data acquisition system, and HBM QuantumX 1609B temperature satellite (optional).

The eDrive testing solution acquires raw data so developers can perform live, detailed analysis during the measurement to determine active and reactive power, as well as energy conversion efficiency. Developers can also carry out a more detailed analysis of:

  • Fundamental and switching frequency
  • Air-gap moment
  • Slip
  • Iron loss
  • Control behaviour



Standard approaches deliver poor results

To measure the efficiency of electric motors, power analysers traditionally have been used on the motor input, and torque transducers traditionally on the motor output. The energy loss is the difference between the electrical power and the resulting mechanical power generated by the electric motor.

However, this method does not allow for statements about the causes of the energy loss. It is the raw measurement data from basic research, not the final results, that provide important insight into the process so developers can make the motors more efficient.

In addition, testers often use measurement devices from different manufacturers, and these devices must be laboriously synchronized before a test. This frequently leads to measurement errors. Moreover, highly dynamic power measurements with more than 50 measurements per second are also technically difficult.


Continuous raw data for verification and analysis

A tool to collect raw data is needed for any profound improvement of electric drives, motors or generators. While a power meter can determine efficiency, it cannot explain that efficiency or help identify approaches that increase efficiency, because the data is already compressed.

HBM’s eDrive solution continuously stores all relevant data, including currents, voltages, torque, rotational speed and even motor temperature – at high resolution in an integrated system. Additionally, root-mean-square (RMS) values – along with active, apparent and reactive power – are displayed in real time during the measurement, just like with a power meter.

Using powerful mathematical functions and a formula database, the eDrive solution takes measurements and performs analysis directly in the system, instead of requiring separate math packages. This integration saves users time, improves flexibility and lowers the error ratio.


Motor test and analysis

The eDrive solution’s formula database enables electric motor and generator data to be directly and quickly evaluated. Two simple measurements, no-load and short-circuit, in combination with built-in formulas, make it easy to determine the equivalent circuit diagram and other tasks.

By applying corresponding formulas to the raw data, the solution can calculate complex parameters directly in the system. Parameters include:

  • Air-gap moment
  • Starting torque
  • Slip
  • Cogging torque
  • Starting or armature currents
  • Many other characteristic quantities directly in the system


The HBM eDriveTesting solution will be on show at the EIS Instrumentation, Testing & Analysis show on 15th March at Silverstone Conference & Exhibition Centre, on stands 66 & 67.




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