汽车直流散热风扇电磁干扰测试分析与优化

Measurement Analysis and Optimization of Electromagnetic Interference of Automotive DC Cooling Fans

用于汽车发动机或动力电机的散热风扇广泛采用有刷直流电机。由于其换向器的电流换向过程有电刷电弧,产生干扰信号,存在严重的电磁兼容,使散热风扇成为车内重要的电磁干扰源。根据国家标准GB/T 18655与欧洲标准CISPR 25,汽车零部件的电磁干扰必须受控在规定的限值内。针对一款汽车散热风扇,结合预评估测试,详细分析了其电磁干扰机理,选取合适参数进行了滤波设计,按照GB/T 18655标准测试,结果在主要干扰频点电磁干扰强度降低了35~40 dB/μV,证明了该滤波方案的有效性。所研究的电磁干扰测试分析与优化过程可应用到解决其他类似电气电子产品的电磁兼容问题。

Brushed direct current(DC)motors are widely used in cooling fans for automobile engines or power motors.Due to the current commutation process of the commutator and the brush arc,the brushed DC motor inevitably generates interference signals,so there is a serious electromagnetic compatibility problem,as the electronic cooling fan is an important electromagnetic interference source in the vehicle.According to the Chinese national standard GB/T 18655 and the European standard CISPR 25,the electromagnetic interference of automotive parts shall be controlled within the required limits.The electromagnetic interference mechanism is analyzed for an automotive cooling fan in detail combined with a pre-evaluation test.A filter is designed through designing appropriate parameters.The test results show that the electromagnetic interference intensity decreases by 35~40 dBμV at the main interference frequency point according to GB/T 18655,which proves the effectiveness of the filtering scheme.Thus the process of electromagnetic interference mechanism analysis and optimization proposed in this research can be applied to electromagnetic compatibility problems of other similar electrical and electronic products.