In the design of nickel zinc common mode inductors, achieving a precise balance between inductance and leakage inductance is a key task, which directly affects the performance of the inductor in the circuit.
First, the choice of core material and structure is crucial. Nickel zinc ferrite cores are one of the commonly used choices because of their high resistivity and good high-frequency characteristics. In terms of core structure, for example, the use of toroidal cores can provide relatively low leakage inductance because their magnetic field distribution is relatively uniform and the magnetic lines of force are concentrated inside the core. As for the control of inductance, it can be achieved by adjusting the size, permeability and other parameters of the core. Larger core size and higher permeability usually increase inductance, but at the same time, the potential impact on leakage inductance must be considered to avoid a significant increase in leakage inductance due to excessive pursuit of inductance.
Secondly, winding design is the core link in balancing inductance and leakage inductance. The number of turns of the winding directly affects the inductance. The more turns, the greater the inductance. However, an increase in the number of turns may also lead to an increase in leakage inductance because more turns will make the coupling between windings incomplete. In order to reduce leakage inductance, techniques such as bifilar winding or layered winding can be used. When two wires are wound in parallel, two wires are wound on the core at the same time, which can make the magnetic field distribution more uniform and effectively reduce the leakage inductance. Layered winding is to wind the primary and secondary windings on different layers respectively to reduce the interlayer capacitance and leakage inductance. At the same time, during the winding process, attention should be paid to the tightness and uniformity of the windings to avoid local looseness or unevenness, so as not to affect the balance of inductance and leakage inductance.
Furthermore, the use of insulating materials should not be ignored. Suitable insulating materials can minimize the interference with the magnetic field distribution while ensuring electrical isolation between windings. Choosing insulating materials with low dielectric constant and thin thickness can reduce the capacitance between windings, thereby indirectly affecting the leakage inductance. For example, using high-performance polyester film or polyimide film as an insulating layer can not only meet the electrical insulation requirements, but also reduce the negative impact on the inductance performance.
Finally, after the design is completed, accurate testing and optimization are essential steps. Use professional inductance test instruments, such as LCR meters, to measure the inductance and leakage inductance of the designed nickel zinc common mode inductor. According to the measurement results, the parameters such as the core, winding or insulation material are fine-tuned to achieve a precise balance between inductance and leakage inductance. Through repeated testing and adjustment, it is ensured that the inductor can meet the circuit's requirements for inductance in actual applications, while the leakage inductance is controlled within an acceptable range, thereby improving the performance and stability of the entire circuit.
