The Q value of wound patch inductance is the main parameter for measuring inductance devices. When the inductor works under AC voltage with a certain frequency, the inductance is higher than the equivalent loss resistance. The higher the Q value of the inductor, the smaller the loss and the higher the efficiency. The Q value of the wound patch inductor is an important parameter reflecting the coil quality, and improving the Q value of the coil can be said to be one of the key points that should be paid attention to in winding coils. So what are the ways to improve the Q value of wound patch inductance? Let's learn about it with Xiaobian, as follows.
1, selecting coil wires according to the working frequency;
Analysis: Inductive coils working in low frequency band generally adopt insulated wire windings such as enameled wires. The working frequency is above tens of thousands of Hz, and in circuits below 2MHz, multi-strand insulated wire windings are used. In this way, the surface area of the conductor can be effectively increased, and the influence of skin collection effect can be overcome, so that the Q value is 30%-50% higher than that of the coil of a single wire winding with the same cross-sectional area. In a circuit with a frequency exceeding 2MHz, the inductor must be wound with a thick wire, the diameter of which is generally 0.3 mm -1.5 mm. Interwound inductor is usually wound with silver-plated copper wire to improve the conductivity of the wire surface. At this time, it is unfavorable to choose multiple wires to wind, because when the frequency of multiple insulated wires is high, the coil insulation medium will cause extra loss, and its effect is not as good as that of a single wire.
Second, choose high-quality coil bobbin to reduce dielectric loss;
Analysis: In the case of high frequency, such as short wave band, because the dielectric loss of common coil frame increases significantly, it is necessary to select high-frequency dielectric materials, such as high-frequency porcelain, polytetrafluoroethylene, polystyrene, etc. as the frame, and adopt the intertwining method for winding.
Third, choose a reasonable coil size;
Analysis: Choosing a reasonable coil size can reduce the loss of a single-layer coil with a certain outer diameter (φ20 mm -30 mm). When the ratio of winding length L to outer diameter D increases/decreases =0.7, its loss is the smallest; The rise/fall of multilayer coil with a certain outer diameter is 0.2-0.5, and the loss is the smallest when t/d is 0.25-0.1. When the winding thickness t, winding length l and outer diameter d satisfy 3t+2L=D, the loss is also the smallest. When the coil with shield is used, its rise/fall =0.8-1.2 is the best.
Fourth, choose a reasonable shield diameter;
Analysis: Using shield will increase coil loss and reduce Q value, so the size of shield should not be too small. However, if the size of the shield is too large, it will increase the volume. Therefore, we should choose a reasonable shield diameter and size, and the ratio of the shield diameter tantalum to the coil diameter D, i.e. Ds/D=1.2.5, will decrease by less than 10%.
5. Using magnetic cores can significantly reduce the number of coil turns;
Analysis: The magnetic core is used in the coil, which reduces the number of turns of the coil, not only reduces the resistance value of the coil, but also improves the Q value, and reduces the volume of the coil.
Sixth, choose a larger coil diameter properly;
Analysis: Choosing a larger coil diameter is beneficial to reduce the loss if possible, and choosing a larger coil diameter to increase the volume is beneficial to reduce the coil loss. Ordinary receiver, the diameter of single-layer coil is 12 mm -30 mm; The multilayer coil is 6mm-13mm, but it cannot exceed 20mm-25mm in volume.
Seven, reduce the distribution capacity of winding coil;
Analysis: as far as possible, the distribution capacity can be reduced by 15%-20% by using the coil without skeleton winding or the coil on the winding rib frame; Segmented winding can reduce the distributed capacity of multilayer coil by 1/3 ~ 1/2. For multilayer coil, the smaller the diameter D, the smaller the winding length L, the larger the winding thickness T and the smaller the distributed capacity. It should be pointed out that the distribution capacity of the coil after dirt and coating increases by 20%-30%.
Conclusion: To sum up, coil winding always focuses on improving Q value and reducing losses.
