Development of accurate measurements of power losses in energy-optimized apparatus and systems
A measurement system has been built, for Calorimetric Measurement of power in the range 1-50 watt, at test temperatures between 20 and 70 deg. C. This Measurement System is intended to provide a service to research and development engineers working with Power Electronics.
Energy efficiency was allocated a high priority in the Danish National Energy White Paper 'Energy 21' (Danish Energy Policy). To evaluate the results of research project in this area, it will be necessary to have a reliable reference and measurement system. In the area of electrical energy conversion, with emphasis on power electronics, electrical machines and drive systems, such a systems is currently not available in Denmark. It is proposed that we will make a system for direct measurement of power losses in electrical and associated components and apparatus. The calorimetric method has been selected as basis for the proposed system. Efforts will be made to design a system with a short time to measurement by studying the interaction between the power losses and the thermal properties of the calorimeter by modelling the proposed system. The proposal encompasses the development of computer models, simulations, at least one calorimetric watt meter capable of accurate measurements in the range (power loss
Applications for the Measurement System are precision measurements of the power loss in circuits and components, e.g. coils, transformers and power electronics systems. Power losses in these types of apparatus are characteristically difficult to measure, because of the waveforms of current and voltage which occur, non-linear material properties, very small values of loss, and high efficiency. The main purpose of performing precision measurements is to enable verification of the loss values, and the basic loss mechanisms. Knowledge and improved models obtained in this way will enable improved simulations, which are important in connection with optimisation of the loss characteristics and energy performance of apparatus and systems. The principle of the wattmeter is to make a calorimetric measurement of the form of heat emitted inside a reference surface. An advanced control system is provided, to regulate the temperature inside the reference surface. The temperature gradient across the walls of the reference surface is also controlled, to ensure that all heat is removed from the space via the heat exchanger of the precision measurement system. The design of the wattmeter is flexible, so that several experimental methods may be employed. To further ensure precision measurements the operation conditions of the measurement heat transfer system are optimised to suit the value of power to be measured. Experiments have verified that the mesurement uncertainty is 59 mW in the power range 1 to 10 W, for a test temperature of 30% C. An offset of 60 mW has been observed in this range, giving a final uncertainty on the measured value of #+-# 30 mW. The uncertainty increases to 180 mW in the range 10 to 50 W, also at 30 deg. C. Currently, only few measurements are available in the latter range, and for other test temperatures. Further studies will increase the understanding of the operation and precision of the wattmeter throughout the range. The system will be maintained and developed continuously
Key figures
Category
Participants
| Partner | Subsidy | Auto financing |
|---|---|---|
| BANG & OLUFSEN A/S | ||
| GRUNDFOS A/S | ||
| Danfoss A/S | ||
| ABB A/S |
Contact
Pontoppidanstræde 101
DK-9220 Aalborg Øst, Denmark
Pedersen, John K. (lektor), 96359240, inst_sekr@iet.auc.dk
Øvr. Partnere: Bang og Olufsen A/S; Grundfos A/S; Danfoss A/S; ABB Motors A/S
