This paper first reviews three internationally standardized core loss measurement methods: Epstein frame, Toroids and Single Sheet testers. A comparison of the Epstein frame and toroid test results is presented for annealed and unannealed steel. Two methods are used to predict core losses under non-sinusoidal supplies. The first method uses the Fourier series and an improved loss separation algorithm to predict core losses under equivalent brushless dc motor flux waveform with known spectrum. For lower harmonics, superposition yielded results close to the measured values. The second method uses the form factor concept and an improved loss separation algorithm to predict core loss. The combination of the improved loss separation algorithm and the form factor concept was found to yield results close to the measured losses under high frequency supplies, such as pulse width modulated waveforms. An Epstein frame with commercial 0.0140-inch electrical steel was used for direct core loss measurements; the methods and test bench used are detailed in the paper, along with test results.
This paper first reviews three internationally standardized core loss measurement methods: Epstein frame, Toroids and Single Sheet testers. A comparison of the Epstein frame and toroid test results is presented for annealed and unannealed steel. Two methods are used to predict core losses under non-sinusoidal supplies. The first method uses the Fourier series and an improved loss separation algorithm to predict core losses under equivalent brushless dc motor flux waveform with known spectrum. For lower harmonics, superposition yielded results close to the measured values. The second method uses the form factor concept and an improved loss separation algorithm to predict core loss. The combination of the improved loss separation algorithm and the form factor concept was found to yield results close to the measured losses under high frequency supplies, such as pulse width modulated waveforms. An Epstein frame with commercial 0.0140-inch electrical steel was used for direct core loss measurements; the methods and test bench used are detailed in the paper, along with test results.
This paper presents a new Epstein frame optimized for high frequencies and high flux densities. The design philosophy and test results at high power frequencies are presented. The frame achieves high frequency and high flux density performance because of reduced number of turns and reduced number of samples, while using standard 25-cm Epstein samples. For the current application, only the 0.0140-inch (0.36 mm) M45 was used. Measured results obtained show good agreement with the core loss data provided by the steel manufacturers measured using the old frames, at 200 Hz, 300 Hz and 400 Hz. Results at 600 Hz and 1.0 kHz are also presented for the M45 samples along with the test bench used.
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