Analysis of Single-Phase 50-kW 16.7-Hz PI-Controlled Four-Quadrant Line-Side Converter Under Different Grid Characteristics

Four-quadrant line-side converters supplying pulsewidth-modulation (PWM)-inverter-fed induction machines are a standard application in ac railway traction vehicles. In the scope of an extensive project aiming at an advanced overall control scheme for traction vehicles taking, among others, grid interaction and stability into account, the steady-state and transient operations of a single-phase 50-kW 16.7-Hz four-quadrant line-side converter is analyzed in detail. The converter is fed either by an inverter or via a slip-ring induction generator with dc excitation, operating as railway-grid rotary-converter representation. In this paper, the structure of the 50-kW test bench, representing a railway grid and a traction vehicle, the applied simulation concept, and the personal-computer-based real-time control hardware used are introduced. Measurement results for sinusoidal as well as highly disturbed line voltage verify the proper operation of the line-side converter, whose proportional-integral control scheme is described in detail. Two different loads are used: switched resistor and motor PWM inverter.