What are the advantages of toroidal transformer

<p>What are the advantages of the toroidal transformer? The core of the toroidal transformer is made of high-quality cold-rolled silicon steel sheets (the thickness of the sheet is generally less than 0.35mm), which is seamlessly rolled, which makes its core performance better than that of the What are the advantages of toroidal transformer The core of the toroidal transformer is made of high-quality cold-rolled silicon steel sheet (the thickness of the sheet is generally less than 0.35mm), which is seamlessly rolled, which makes its core performance better than the traditional laminated core. The coil of the toroidal transformer is evenly wound on the core, and the direction of the magnetic field lines generated by the coil almost completely coincides with the core magnetic circuit. Compared with the laminated type, the excitation energy and core loss will be reduced by 25%, which brings the following series The advantages. </p><p><br></p><p>High electrical efficiency The core has no air gap, the stacking factor can be as high as 95% or more, the core permeability can be 1.5 to 1.8T (the laminated core can only be 1.2 to 1.4T), the electrical efficiency is up to 95%, and the no-load current is only 10% of the laminated type. The small size and light weight toroidal transformer can reduce the weight by half compared with the laminated transformer. As long as the core cross-sectional area is kept equal, the toroidal transformer can easily change the ratio of the length, width and height of the core, and the outer size can be designed to meet the requirements. The magnetic core with low magnetic interference has no air gap, and the winding is evenly wound on the toroidal core. This structure results in small magnetic leakage and small electromagnetic radiation. It can be used in high-sensitivity electronic equipment without additional shielding. For example, it is used in low-level amplifiers and medical equipment.</p><p><br></p><p>Vibration noise is small. The core does not have an air gap to reduce the core. Product classification According to foreign literature, <a href="https://www.fs-xwd.com/xianweida-toroidal-transformers-oem-odm" rel="noopener noreferrer" target="_blank">toroidal transformers</a> can be divided into three types: standard type, economic type and isolated type. The characteristics of each type are: series capacity 8 ~ 1500VA, there is a small The voltage regulation rate and temperature rise at full load operation are only 40 ° C, allowing short-term overload operation, suitable for demanding use occasions. Class B (130 ° C) polyester film insulation is used between the primary and secondary windings. At least three layers of insulating tape are required to withstand the voltage test of AC 4000V and 1min. What are the advantages of toroidal transformer How is the transformer power calculated Calculate the transformer input power P1 (set the transformer efficiency η = 0.95) and the input current I1 where: K—the coefficient is related to the transformer power, K = 0.6 ～ 0.8, take K = 0.75; select the core size according to the existing core specifications as : Height H = 40mm, inner diameter Dno = 55mm, outer diameter Dwo = 110mm. In the formula: f—— power frequency (Hz), f = 50Hz; B—— magnetic flux density (T), B = 1.4T. N2 = N20 · U2 = 3.23 × 11.8 = 38.1 turns, take N2 = 38 turns. 6) Select the wire diameter. The wire diameter d of the winding wire is calculated according to formula (10). Where: I——current through the wire (A); j——current density, j = 2.5 ～ 3A / mm2. When taking j = 2.5A / mm2 into the formula (10), two wires with d = 2.12mm (considering the maximum outer diameter of the insulating paint is 2.21mm) should be used and wound. Because the cross-sectional area of ​​the Φ2.94 conductor Sd2 = 6.78mm2, and the cross-sectional area of ​​the d = 2.12mm conductor is 3.53mm2, the cross-sectional area of ​​the two parallels is: 2 × 3.53 = 7.06mm2, which fully meets the requirements and has a large margin . 6 Calculation of the structure of the toroidal transformer The winding of the toroidal transformer is wound by the winding ring of the winding machine in the iron core. Therefore, the size of the inner diameter of the iron core is very important for the processing process. </p><p><br></p><p>The purpose of the structure calculation is to check the complete winding After the winding, how much space is left in the inner diameter. If the calculated inner diameter space is too small to meet the winding requirements, the core size can be modified, as long as the cross-sectional area remains unchanged, the electrical performance is basically unchanged. It is known that the inner diameter of the core Dno = 55mm, the thickness of each insulating layer in FIG. 7 is to = 1.5mm, and t1 = t2 = 1mm. Calculate the inner diameter Dn2 after winding the primary winding and covering the insulation. Calculate the number of turns of each layer of the primary winding n1 where: Dn1-the inner diameter after the core is insulated, Dn1 = Dno-2t0 = 55- (2 × 1.5) = 52mm ; kp——overlap coefficient, kp = 1.15. Then the number of layers of the primary winding Q1 is the thickness of the primary winding δ1. Transformer temperature rise problem Temperature rise problem The temperature rise characteristic curve of the toroidal transformer is shown in Figure 6. From Figure 6, it can be seen that the temperature rise of the toroidal transformer is relatively low. For the standard series, even if the overload is 120%, the temperature rise does not exceed 70 ° C. The temperature rise of the transformer is determined by the iron loss and the copper loss. For the laminated transformer, the two parts are basically equal, but the toroidal transformer is wound with high-quality cold-rolled silicon steel sheets and cooperates with a good annealing process. The loss is only (10 ~ 20)% of the total loss, so the temperature rise is mainly determined by the copper loss of the winding. The reasonable design is that the power consumption of the primary and secondary windings should be basically balanced. The temperature rise is also closely related to the heat dissipation area. Since the temperature rise of the core of the toroidal transformer is low, the winding is evenly wound on the entire core, the heat dissipation area and the heat dissipation conditions are better, so a lower temperature rise can be obtained.</p>