During the exchange cycle, the energy consumption caused by the magnetic energy change of the magnetic core power inductance is the difference between the magnetic energy stored in the magnetic core during the on-time and the magnetic energy extracted by the magnetic core when it is off. Therefore, the total energy stored in the magnetic core is the shaded area of the B-H loop in Figure 2 times the volume of the magnetic core. When the power inductor current decreases, the magnetic field strength decreases, and the magnetic flux density changes along the different paths in Figure 2 (according to the direction of the arrow). Most of the energy will enter the load. The difference between the stored energy and the emitted energy is Energy consumption. The energy loss of the magnetic core is the area drawn by the B-H loop multiplied by the volume of the magnetic core. This energy multiplied by the switching frequency is the power loss. The hysteresis loss depends on the function. For most ferrite materials, n is approximately in the range of 2.5 to 3, but this is only effective when the core is not saturated and the exchange frequency is within the specified operating range. . The shaded area in Figure 2 shows that the first quadrant of the B-H loop is the operating area of magnetic flux density, because most of the boost and buck converters operate with positive inductor current.

　　 The second loss source of magnetic core power inductors is eddy current. Eddy current is the current caused by the magnetic flux change of the magnetic core material. According to Lenz's Law, the change of magnetic flux will bring a reverse current that is opposite to the direction of the initial magnetic flux change; this current called eddy current will Flow into the conductive core material and cause power loss. This can also be seen from Faraday's law. The power loss of the magnetic core caused by the eddy current is proportional to the square of the rate of change of the magnetic flux of the magnetic core. Since the rate of change of magnetic flux is directly proportional to the applied voltage, the power loss of the eddy current will increase with the square of the applied inductor voltage and is directly related to its wave width. Compared with the loss in the hysteresis interval, the eddy current of the magnetic core is usually much lower due to the high resistance of the magnetic core material. Usually, the data of the magnetic core loss will be included in the hysteresis interval and the loss of the core eddy current.

　　It is usually quite difficult to measure the core loss, because it contains quite complicated test setup arrangement for measuring the magnetic flux density and estimation of the hysteresis loop. So far, many inductor manufacturers have not provided this information, but some can be used to estimate some characteristic curves of inductor core loss. This can be determined by the ferrite material manufacturer, peak-to-peak magnetic flux density and The function of frequency is derived. If you know the specific ferrite material and volume used in the inductor core, you can use these curves to effectively estimate the core loss.

This kind of curve, such as the ferrite material in (Figure 3), is obtained by adding a sine wave changing voltage of a bipolar magnetic flux change signal. When using a square wave pattern (including higher frequency harmonics) and a unipolar magnetic flux When the core loss of a DC-to-DC converter is estimated during operation, the basic frequency and 1/2 of the peak-to-peak magnetic flux density can be used to estimate the core loss. The volume or weight of the inductor can also be measured or calculated.

　　 The power loss of the magnetic core of the power inductor

　　Some inductor manufacturers provide core loss diagrams, or equations that can be used to obtain more accurate core power loss estimates. In some manufacturers' inductor data specifications, they provide inductors core loss equations. The core loss is provided by an equation using constants (K-factors), so the core loss can be calculated from the frequency and the peak-to-peak inductor current ripple function. On the other hand, manufacturers will also graphically provide core losses for many inductor products.

　　 SMD inductance is an attribute of closed loop. When the coil of the chip inductor passes current, the chip inductor forms a magnetic field induction in the coil, and the induced magnetic field generates an induced current to resist the current passing through the coil. The role of the chip inductor in the circuit is to generate a changing magnetic field when passing an unstable current, and this magnetic field will in turn affect the current. The chip inductor is like an inductor in the power circuit, and the inductor is direct to DC , It is high resistance to high-frequency pulses, so it plays the role of DC resistance to AC pulses.

　　Resistor is used to control the current in the circuit. Capacitors are used to block DC and AC, and inductors are used to block high-frequency and low-frequency. On the other hand, capacitors and inductors are energy storage components, so there is a filtering effect in the circuit. The chip inductor has the characteristic of preventing the passage of alternating current and allowing direct current to pass smoothly in the circuit. The characteristic of the inductance is direct current and resistance to alternating current. The higher the frequency, the greater the coil impedance. Inductors often work with capacitors in circuits

　　The inductance coil has the characteristic of preventing the current change in the AC circuit. Inductance coils have characteristics similar to the inertia in mechanics. They are named "self-induction" in electricity. When the chip inductors are at low frequencies, the inductors generally exhibit inductance characteristics, which only store energy and filter high frequencies. At high frequencies, its impedance characteristics are very obvious. There are phenomena such as energy consumption and heat generation and reduced inductive effects. The high frequency characteristics of different inductors are different.