Stability analysis of a torque current ripple detecting type phase angle modulation beat-less control system for ac-fed railway vehicles

A problem in AC-fed railway vehicles is the ripple of the DC-bus capacitor voltage owing to the single-phase power supply. Therefore, beat-less control is required to compensate the effects of voltage ripple in order to obtain smooth torque of the traction motors. This paper deals with a torque current ripple detecting type phase angle modulation beat-less control system for AC-fed railway vehicles. It is difficult to design the control constants theoretically without simulations because of the complexity and nonlinearity of this control system. Therefore, the stability analysis is conducted to establish the design method of this beat-less control system.