Design of a Controllable Wideband Voltage Injection Device for High-speed Train Impedance Measurement

Wideband impedance measurement of high-speed train is crucial to small-signal stability analysis in the electric railway system. In the measurement process, the wideband disturbance device plays a vital role in exciting the desired wideband responses. However, there is few corresponding wideband disturbance devices for high-speed train, which needs to be studied further. To fill this demand gap, this paper proposes a controllable wideband voltage injection device, whose control structure comprises dual closed-loop rectifier control and open-loop inverter control. The former provides a stable and adjustable DC voltage, and the latter conducts wideband voltage inversion. By this device, a multitone voltage signal can be generated, whose spectrum energy is uniformly distributed in the desired frequency band. Then it will be injected into the traction electrical drive system of high-speed train to excite wideband responses for impedance calculation. The simulation results can well validate the effectiveness of the proposed device.