Getting beyond numerical results


Evaluating motor efficiency has become extremely important since significant efforts are focused on more efficient electrical machines and drives. The main issue is how to implement an accelerated procedure that obtains the motor or drive efficiency for all operating points safely, accurately and rapidly.

Ordinary test methods using a typical power analyzer only offer inadequate numerical results. To get beyond numerical results, all electrical, mechanical and physical signals must be acquired simultaneously at high sample rates coupled with advanced real time custom analysis and fast data transfer to automation systems, making it possible to perform electric motor and drive efficiency mapping accurately and rapidly, as well as almost any type of advanced analysis.

Electrical drives are used in a wide variety of applications, basically every electrical machine that is inverter driven or contains a variable speed drive. The key is to design and test for the maximum efficiency at all operating points in the entire drive train safely, accurately and rapidly.

Traditionally, signals along the drive train are measured with a wide range of measurement systems. For example, digital multimeters are used for battery voltage and current measurements and traditional power analyzers for measuring the output of the inverter. Sometimes a scope is used to view the signals. To measure machine output, a torque sensor and some type of data acquisition system is used.

Unfortunately, there are several issues with this traditional setup:

  • There is no time synchronization between all the measurement systems; therefore, it is difficult or nearly impossible to make comparisons between mechanical (torque/ speed) and electrical (voltage/current) signals at the same point in time.
  • No raw data is available; therefore, no advanced analysis can be performed.
  • Typical power analyzers only offer a few calculations per second, not enough for feedback on automation/control systems.
  • Power meters are not reliable during dynamic load changes, start up or any changes in speed, an area that needs further testing and analysis.
  • Verification of results is not possible because no raw data is available, requiring retesting if anything is in question.

As a result, one needs to make several assumptions about issues and errors; make changes based on those assumptions and then retest, which is time consuming and rather costly.

With the eDrive Testing solution, HBM has introduced a revolutionary tool that overcomes the limitations of the typical test method using a high speed data acquisition power analyzer.

Benefits include:

  • Synchronous recording of all drive train signals so mechanical and electrical traces can be compared accurately plus easily configurable to test 3, 6 or 12 phase machines and acquire more signals like CAN, temperature, vibration and strain
  • Real time advanced analysis like motor mapping, dq0 (Park) and Space Vector (Clarke) transformation enables immediate results rather than hours or days
  • Transfer real time calculated results to automation systems via EtherCAT at 1000 results per second
  • Perform real time power calculations per half cycle with a typical 02% Power Accuracy even during dynamic load changes, start up or any changes in speed
  • Verification of results is possible any time because raw data is available, so no retesting is needed if anything is in question

HBM’s new efficiency testing method identifies a revolutionary tool offering significant savings in time and cost while greatly accelerating the ability to analyze electrical motors, inverters and drive trains with any type of rapid analysis in a matter of seconds rather than hours or days.

As a result, this makes it possible to clear the way for even more efficient electric motors, inverters and drive trains at a rapid rate, thereby boosting productivity, capability and research and development in every application that incorporates an electrical machine that is inverter driven or contains a variable speed drive. analyzers


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