Analysis Of Spectrum Structure Of Induction Cooker Noise And Computation Of Contribution

People are also increasingly concerned about the noise problems in our daily life.Induction cooker is gradually becoming an indispensable part of the daily household appliances in the 21 st century because of its many advantages.But it also creates much noise in use,affecting the sense of comfortable.From the perspective of noise source control,in this paper,the noise of the induction cooker is tested.Then the noise spectrum structure is analyzed,and the noise components and its contribution degrees are recognized.These provide some basis on effectively controlling noise of induction cooker.The specific research contents are as follows:(1)Analysis of the characteristics of induction cooker noise sources.Based on the analysis of the operating principle and the compositional structural of induction cooker,it recognizes that the main noise sources of induction cooker should include fan noise(aerodynamic noise mainly),electromagnetic noise,mechanical noise and water boiling noise.According to the mechanism analysis,the spectrum characteristics of the noise sources are obtained.(2)Analysis of the spectrum structure of induction cooker noise.The noises of induction cooker when heating water in different conditions are tested.And then the timedomain noises are used to analyze the influence of different water volumes,different powers,and different placements of the cookware on the noise.Combined with LMS Test.Lab software,the test dates are processed to transform the time-domain data into frequency-domain data.The noise components are separated by analyzing the noise spectrums and the noise color maps of different working conditions.Especially when the cookware is suspended,the spectral analysis of the heating noise of the induction cooker shows the fundamental frequency of 100 Hz and its higher harmonic obviously.It confirms that the vibration of cookware is one of the main vibration and noise radiation sources of induction cooker.Furthermore,the electromagnetic noise component of induction cooker noise is confirmed.The temporal variation characteristics of noise frequency caused by water boiling are observed by analyzing the noise color maps.Electromagnetic vibration also acts on the bottom of the cookware mainly to generate vibration and radiate noise.Therefore,the boiling vibration of the water body and the electromagnetic vibration intercoupled with each other on the cookware,resulting in intercoupled vibration and noise.The intercoupled vibration caused by water boiling is observed by comparing the noise spectrums at different special time points.(3)The contribution calculation of each noise component.The contribution degree of each noise component can be calculated by calculating the changes of the noise in different periods and the proportion of acoustical power.In the early heating stage of induction cooker,electromagnetic noise and fan noise are the mainly noise components.According to the contribution degrees,it can be observed that fan noise contributes more at lower heating power.With the increasing of the heating power,the contribution of electromagnetic noise increases.In the medium heating period,the contribution of water boiling noise is more than 90% when the nucleate boiling occurs.In the late heating stage,transition boiling transforms to film boiling,and the electromagnetic noise is obviously enhanced by the disturbance of the large bubbles at low frequencies,which is the coupled vibration phenomenon.At this stage,the contribution degree of water boiling noise is above 70%.