Chopper-Controlled Steinmetz Circuit for Voltage Balancing in Railway Substations

This paper presents a new technique in voltage balancing for single-phase railway substations. Using the concept of chopper-controlled impedance, the authors study the feasibility of an active Steinmetz circuit based on ac choppers. The low power losses in semiconductor devices make the proposed topology an interesting alternative to classical solutions such as those based on voltage source inverters. Design criteria are presented using information obtained from measurements carried out on a substation of the French National Railways. Finally, the study is validated by means of simulations and experimental results carried out on a 1.5 kVA prototype.