An Active Damping Stabilization Scheme for the Suppression of the DC-Link Oscillation in Metro Traction Drive System

The dc-link oscillation is a typical phenomenon happening in the metro traction drive system (MTDS) due to the negative input impedance associated with the constant power load, which is considered as a thorny problem that needs to be resolved well. This paper proposes an active damping stabilization scheme based on inverter power regulation that can effectively eliminate the dc-link oscillation of the MTDS. The proposed stabilization scheme is mainly composed of two parts: 1) the generation of damping power; and 2) the inverter power control loop. The damping power, linked to the deviation of the dc-link voltage through the gain units, is fed hack to the vector-controlled induction motor drive system to establish the inverter power control loop. From this control loop, the added q-axis current is obtained, which is regarded as the stabilization term. The additional stabilization term is combined with the q-axis current command of the induction motor for achieving the improvements of the drive performance and the system stability. The effectiveness of the proposed active damping stabilization scheme is verified by simulation and hardware-in-the-loop tests.