A differential method of high-frequency magnetics core loss test scheme

Because of its inherent drawbacks, the conventional AC power meter method for magnetics core loss has been limited in some case. A new method based on testing the input power difference with and without the DUT core in the circuit is proposed and it is called as differential method in this paper. The new method eliminates the problem of high errors with AC power meter method due to the phase shift error in the condition of high frequencies and high DUT impedance angles. Its suitable applications are described and analyzed deeply. The test scheme and circuits are also presented which is especially appropriate for the core loss tests with low-frequency current bias, such as in the PFC inductors. Measured results verify the accuracy of the technique by calorimetric method.