Application of Power Filter for Medical Devices

  Since the electromagnetic emission of the medical device is not limited to the switching power supply selected internally, the line filter of the power incoming line portion also becomes an important link for suppressing high frequency interference. There are two common mode interference suppression capacitors (Y capacitors) in the general power line filter, which can control the common mode current of the device, but it is not suitable to use such small capacitors in the power line filter of medical equipment. Because it causes the leakage current of the device to be too large. This selection principle of medical equipment for power line filters has caused designers to lose an effective means of suppressing common mode currents. The only remaining means available is to increase the impedance of the series inductance in the power line filter.

   In order to design a good power line filter, the circuit design of the filter is only a small part. The selection of the internal components of the filter, the layout and structure of the filter and the distribution parameters of the internal components of the filter are the real key factors to determine the performance of the power line filter.