Calorimetric efficiency determination of power electronic variable speed drives

A calorimeter test bench for the efficiency and power loss determination of power electronic variable speed drives is presented. The balanced calorimetric setup with air as the cooling medium is proposed to test small electronic drives for AC motors in a power range from 1 kW up to 7,5 kW. The construction, the required measurement equipment, the measurement procedure and especially the measurement results and uncertainty are important aspects of this test bench and are discussed in this paper. The device under test is a 2,2kW drive which is measured using both the input-output method and the calorimetric method. The test results are compared and conclusions are made concerning usability, repeatability and accuracy of the test bench. The overall goal is to further examine and optimize the calorimetric approach and to be able to obtain more accurate and comparable test results of very high efficient frequency converters. This setup reaches an uncertainty of ±2,39% or ±1,48W on the power loss at full load and speed using the calorimetric method

Energy efficiency measurement procedure for gearboxes in their entire operating range

Over the last decade, forced regulations and a growing social awareness with respect to energy efficiency have resulted in a renewed interest in the research for high efficient electrical machines. When an electrical motor is coupled to a machine, in many cases a gearbox or belt transmission is used. Research shows a lack of information on energy efficiency of these components. In comparison to electrical motors and drives, there is very few regulation and if efficiency values can be found in catalogues, there is no regulated test procedure available to validate the data. As a result, the reliability of these efficiency values is unknown and comparison between manufacturers and technologies is impossible. In this paper a test bench is proposed to measure the energy efficiency of a gearbox with an accuracy up to 0.4%. The test bench is used to measure the efficiency of gearboxes in their entire speed and torque range. Contour maps are used to visualize these measurement results. Moreover, a measurement campaign using different gearboxes is carried out to compare the energy efficiency in the manufacturers catalogue and the measured efficiency

Efficiency measurement strategy for a planetary gearbox with 2 degrees of freedom

This paper discusses a method to calculate the efficiency of a planetary gearbox with 2 degrees of freedom. Standard measurement procedures in which the efficiency is measured as function of the load torque and input speed become infeasible due to the many possible input output configurations. To solve this, a method is proposed that combines the theory of virtual power and a limited set of measurements. The theory of virtual power is used to link the considered power flow in the device with an expression to calculate the efficiency of the planetary gear in terms of the efficiency of the power path between sun & carrier and carrier & ring. The efficiency of the aforementioned power paths is shown to depend only on the torque applied to these paths which means that speed dependent losses such as churning losses are negligible. Measurements of the efficiency as function of the torque applied to the sun for a varying speed ratio between ring and carrier are added to validate the approach

Total drive train optimization of industrial fans and pumps consider-ing VFD driven motor, transmission and load

Standards and mandatory legislations concerning minimum efficiencies of electric motors have entered our world of electromechanical drive trains over the last years. It was a logical step to consider these elements as they account for the largest amount of energy consumption in the European industry. The European ecodesign measures count for 40% of total estimated savings in electric motors by 2020. However, not only the driving motor has to be considered when it comes to optimizing the drive train efficiency. This paper shows the saving potential in other drive train components based on measurement campaigns during several research projects at Ghent University Campus Kortrijk

Efficiency measurement campaign on gearboxes

The last decade, new concepts of electrical motors with promising efficiency have entered the market. Such an electric motor is connected to the load machine often by means of a transmission system. Considering the energy efficiency of transmission systems, there is a lack of available information on the market. In contrast to electrical motors and drives, there are very few mandatory regulations imposed on these components. Information on efficiency can be occasionally found in catalogs but accepted test procedures are not available. As a result, the reliability of these efficiency values is low and comparison between brands and technologies is impossible. Regulation on energy efficiency on the other hand evolves towards a total system approach. The new European fan directive 327/2011 is an example of such an approach where overall efficiency is considered. Information on the efficiency of mechanical transmission components such as gearboxes and belt drives will be required to assess and optimize the overall system efficiency. Due to the lack of reliable information on energy efficiency of these components, a measurement campaign was set up to test a series of gearboxes. This paper discusses the results of this measurement campaign. Because of the wide variation in types and sizing, the measurements where done on a flexible designed input-output gearbox test bench [1]

Direct calorimetric test bench for power drive systems with power losses up to 20 kW

A direct calorimetric test bench is presented, designed to test drives, motors and gearboxes with power losses up to 20 kW and a mechanical output power of 150 kW, up to 6000 rpm. The calorimeter setup is a direct type, therefore it determines the power losses of a device under test (DUT) by measuring the coolant temperatures and flow rate. This type of measurement achieves an uncertainty below 1% on the power loss determination. The construction of the test bench, the required measurement equipment, the measurement procedure and especially measurement uncertainties and results are described in detail. The test case results of a measurement campaign with an electric axle drive, consisting of a liquid-cooled inverter, liquid-cooled high-speed permanent magnet synchronous motor and integrated slip controlled clutch and gearbox, are presented. The calorimetric setup reaches an uncertainty of ±0,7% or ±25,9 W on the power loss at 25 kW mechanical output power