What is the inductance value(L)?

The inductance of an inductive sensor depends on the characteristics of its winding and magnetic core, including the number of windings, winding spacing, winding direction, and magnetic core material. The inductance of an inductive sensor is a fixed value, which represents the magnetic flux inside the inductive sensor. The inductance of an inductive sensor is critical for its operation, as it determines the impedance, voltage, power loss, and frequency response of the inductive sensor.

Operating Temperature of Inductors and Transformers

The operating temperature of inductors and transformers usually refers to the ambient temperature in which they are used, and can be used to measure their performance under different environmental conditions. For example, an inductor product may operate well at room temperature, but may have issues in high temperature environments. Therefore, when selecting inductor products, it is important to consider their performance under different environmental temperatures.

The products provided by Coilmaster Electronics use different raw materials and have different temperature-resistant characteristics to cope with different operating temperatures. For products with a working temperature of 165°C, the product structure, adhesives, wires, and magnetic cores used can withstand a minimum temperature of 180°C. The relevant process control is also more stringent and rigorous than general products. Especially for the magnetic core and wire, we choose a higher Curie temperature for the magnetic core because magnetic materials lose their magnetism at a certain temperature. When the temperature of the magnetic material is higher than the Curie temperature, it loses its magnetism; when the temperature is lower than the Curie temperature, it regains its magnetism. The Curie temperature depends on factors such as the composition and crystal structure of the magnetic material. Currently, the wire used in surface mount inductors is P180 temperature-resistant wire.

Working Frequency

Frequency refers to the frequency of the electromagnetic field required for the operation of an inductive sensor. The frequency range of an inductive sensor depends on the characteristics of its winding and magnetic core, including resistance, inductance, distributed capacitance, etc. The frequency range of an inductive sensor is usually very wide, ranging from low frequency to high frequency, and even ultra-high frequency. Different frequencies will affect the magnetic flux, resistance, and losses of the inductive sensor, so when designing an inductive sensor, the requirements of its operating frequency must be taken into consideration. To meet the requirements of different operating frequencies, magnetic cores, in addition to the commonly used ferrite cores, can also include ceramic cores, amorphous cores, nano-crystalline cores, etc.

Coilmaster Electronics provides customers with appropriate choices based on their specific applications. Another important aspect related to frequency is the self-resonant frequency (SRF). SRF refers to the frequency of an inductor when it is in a self-resonant state. The self-resonant state refers to the combined action of the inductor's inductance and capacitance, producing a sinusoidal oscillation state. In the self-resonant state, the frequency of the inductor is SRF. SRF is an important parameter of the inductor, which determines the frequency range of the inductor in its operating state. When selecting an inductor, attention should be paid to its SRF value to ensure that the inductor can operate normally within the required frequency range. Usually, the SRF value of an inductor is between several hundred kHz and several hundred MHz. Generally, the self-resonant frequency of ceramic cores is the highest and can reach GHz, followed by nickel-zinc alloy cores in ferrite cores, and then manganese-zinc alloy cores.

What is the saturation current (Isat) and temperature rise current (Irms)?

The maximum current value that an inductor can withstand under normal operating conditions is called the rated current of the inductor, which reflects its current withstand capability. When using an inductor, it is important to pay attention to the current rating limit to avoid damaging or burning out the inductor. Current is divided into rated current and saturation current, and in the specification, the minimum value of the two is used as the definition of the current reference. For example, if the rated current is 3A but the temperature rise current is only 2A, the defined current value in the specification is 2A. So what is the difference between saturation current and temperature rise current? The temperature rise current refers to the current value corresponding to the internal temperature rise generated during the normal operation of the inductor. The inductor generates heat during operation, which causes its internal temperature to rise. This temperature rise affects the performance of the inductor, so the inductor temperature rise current must be considered when designing the inductor.

Generally, the larger the inductor temperature rise current, the stronger its heat dissipation ability, the smaller the temperature rise, and the better the performance of the inductor. Saturation current refers to the current value when the internal magnetic flux of the inductor reaches saturation during operation. When current flows through the inductor, a magnetic field is generated inside the inductor, and as the current increases, the magnetic field strength also increases. When the magnetic field strength reaches a certain level, the magnetic flux inside the inductor will reach saturation, and the current value of the inductor at this time is the saturation current of the inductor. The saturation current of the inductor is an important electrical characteristic that determines the maximum operating current value of the inductor in working state. Generally, the larger the saturation current of the inductor, the greater its capacity. Inductors are more likely to saturate in higher ambient temperatures. Generally, the rate of decrease in the definition of saturation current is around 30% of the change in the measured inductance when unloaded.

Quality factor

The quality factor (Q factor) of an inductor is an important parameter that measures the quality of the inductor. It represents the ratio between the energy storage capacity and energy loss of the inductor, i.e., the ratio of energy stored by the inductor in one cycle to the energy lost in the same cycle. A higher Q factor indicates a stronger energy storage capacity and lower energy loss, which means a higher quality inductor. When choosing an inductor, attention should be paid to its Q factor to ensure its quality and performance.

Direct current resistance(DCR)

Ceramic is one of the common materials used for inductor cores. Its main purpose is to provide a form of the coil. In some designs, it also provides the structure to hold the terminals in place. Ceramic has a very low thermal coefficient of expansion. This allows for relatively high inductance stability over the operating temperature ranges. Ceramic has no magnetic properties. Thus, there is no increase in permeability due to the core material.