滤波器选型（Filter selection）.docVIP

滤波器选型（Filter selection） The filter selection needs to consider the following points: 1 voltage This voltage requirement is a range which is the synthesis of the steady-state voltage + ripple voltage. 2 current The current index is critical. It determines the inductance of the filter winding, copper wire and lead wire diameter. If selected, a large current on a thin wire, such as a small cart, causes serious heat and burns. This current is also a range of steady-state current + ripple current maximum. 3 EMC requirements Since it is a filter, in order to filter out some undesired frequency bands, the effect of filtering is usually determined by the visual results of EMC test standards and field applications. In particular, the power filter, it is best to determine the product through which the filter is required to adopt standards, according to the standard requirements of different, in the choice of a specific test band requirements. The main targets of the power filter are transmit emission CE and conduction immunity CS, and the signal filter mainly depends on the requirements of the EMC standard for the undesired input frequency band and the undesired output frequency band. For example, no lamp for rectifier, itself a switch working state, there will be foreign launch, EMC test will focus on examination of the switching frequency and the harmonic components of the conduction interference filter is needed for these specific frequency or frequency has enough filtering effect. 4 safety standards requirements Readers might find it strange to choose filters, and say, what do security standards do? This is because the filter is generally used in the power input and board interface, these parts are the security problems of the hardest hit areas. Is equal to the filter, a body to undertake a number of requirements. The safety regulations related to the filter are three indexes: insulation, withstand voltage, leakage current, residual voltage and residual energy. LN insulat