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What are the core loss sources?
Apr 11, 2017

                 

                   What are the core loss sources?


1, the loss of energy

 the core loss.png

In the magnetic power inductive switching cycle, the energy loss caused by the change of the magnetic energy is the difference between the magnetic energy stored in the magnetic core and the magnetic energy extracted by the magnetic core during the on-time. When the power inductor current decreases, the magnetic field strength decreases, and the magnetic flux density changes along different paths. Most of the energy will enter the load. The difference between the stored energy and the emitted energy is the loss of energy.


2, eddy current


The eddy current is the current caused by the flux change of the core material. According to Lenz's law, the change of magnetic flux will produce a reverse current which is opposite to the direction of initial magnetic flux change. This current, called eddy current, will flow into the conducting magnetic. Core material and cause power loss. This can also be seen by Faraday's law. The core power loss due to eddy currents is due to the square of the core flux change rate.


Since the flux change rate is directly proportional to the applied voltage, the power loss of the eddy current increases with the square of the applied inductor voltage and is directly related to its wave width. Compared to the hysteresis interval loss, the core eddy current is usually much lower due to the high resistance of the core material. Usually the data of the core loss will also include the hysteresis zone and the loss of the core eddy current.


Measuring the core loss

Everyone knows that measuring the core loss is very difficult because of the test setup arrangement used to measure the magnetic flux density and the estimation of the hysteresis loop. Inductive manufacturers have so far provided no information in this regard, but there are some characteristic curves that can be used to estimate the loss of the inductor core. Reference Example 2 This can be done by a ferrite material manufacturer, with peak-to-peak magnetic flux density and The frequency function is derived. If you know the specific ferrite material used in the inductor core and the size of the volume, you can use these curves to effectively estimate the core loss.


Note:

1 Faraday's law - Faraday's law is to describe the relationship between the amount of electricity passing through the electrode and the weight of the electrode reactant. Also known as the law of electrolysis, it is the basic law followed in the electroplating process.

2 Inductance Core Loss Characteristic Curve

     core loss.png

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