The causes and noise reduction ideas of iron core noise in magnetic voltage regulators
The noise generated by magnetic voltage regulators during operation is rooted in the iron core. Under the action of an alternating magnetic field, the size of silicon steel sheets undergoes small changes, a phenomenon known as magnetostriction. Due to the fact that the variation period of magnetostriction is half a cycle of the power frequency, the resulting vibration of the body is manifested as a continuous low-frequency buzzing with twice the power frequency as the fundamental frequency. It can be said that the vibration of silicon steel sheets is mainly determined by the magnetostrictive properties of ferromagnetic materials.
The magnitude of magnetostriction is not fixed and is constrained by various factors. Firstly, the material of silicon steel sheets: under the same magnetic field strength, the better the material, the smaller the magnetostriction and the lower the noise of silicon steel sheets; On the contrary, the greater the magnetostriction, the greater the noise. Next is the magnetic field strength itself: the stronger the magnetic field, the more obvious the magnetostriction, and the noise increases accordingly.
The surface condition and heat treatment process of silicon steel sheets are equally critical. Whether the surface of silicon steel sheet is painted or not will affect magnetostriction - the coating has adhesion to the silicon steel sheet, which can suppress its deformation and reduce vibration. The influence of annealing process is more significant: under the same magnetic field strength, annealed silicon steel sheets have much smaller magnetostriction than unannealed silicon steel sheets, because selecting the optimal annealing process can significantly reduce the magnetostriction rate.
In addition, the no-load noise of transformers is closely related not only to factors such as material, but also to the condition of the iron core joints. The tightness and flatness of the seams directly affect the continuity of the magnetic circuit, which in turn affects the noise level.
Overall, the noise reduction of magnetic voltage regulators should start from three aspects: materials, processes, and structures: selecting high-quality silicon steel sheets with low magnetostriction, optimizing annealing processes to fully release internal stress, ensuring surface coating quality, and strictly controlling the process accuracy of iron core joints. These measures start from the source of noise and are the most fundamental and effective way to reduce the noise of magnetic regulators.
