An analytical approach for DC-Link DM filter design for BL motor drives

This paper presents a detailed procedure for DC-Link Differential Mode filter design for DC Brushless Permanent Magnet Motor Drives. The goal is to design filter to attenuate Differential Mode noise below specified limits, caused by PWM controlled motor load current. The specified limits are defined by DO-160 Section 21 or MIL 461 CE102. Analytical calculation is used to estimate DC-Link current harmonics based on motor parameters and load conditions. Once unfiltered DC-Link current harmonics defined the filter Insertion Loss (IL) can be estimate to comply with above standards. All analytical results are compared with the results of PSPICE and MATCAD analysis. As a final check the harmonics spectra of input inverter current measurement will be done on a motor drive and compared to the analytical results.