Permanent magnet synchronous motors require sampling of the motor phase current during vector control. During the sampling process, many factors such as reference level fluctuations can cause the phase current to contain DC components. In addition, online parameter estimation methods such as DC voltage injection also introduce DC components into the phase current. This article provides a detailed analysis of the generation mechanism of DC components in different situations, and investigates the impact of DC components on control effectiveness, torque ripple, efficiency, and other performance. Propose a data processing method that can filter out the DC component in three-phase AC signals. This method can effectively suppress the DC component introduced by different factors, thereby increasing control stability and improving the efficiency of the motor system. Simulation and application practice have verified the effectiveness of the algorithm.