Abstract: In high power four-quadrant converter（4QC） applications such as traction driven systems,the switching frequency is limited to several hundreds hertz.Therefore,the traditional direct current control method fails to acquire ideal performance.Based on static orthogonal coordinate system,this paper uses a current decoupling control scheme on single-phase 4QC,which realizes the individual control of active power as well as reactive power.It enhances system robustness by the closed loop control of active and reactive current root mean square（RMS） values.Carrier phase-shifting control for parallel converters is applied;hence line current harmonic components are greatly reduced.Especially,active and reactive current-equalizing control loops are designed to eliminate the circular current within parallel rectifiers.The control strategies above are successfully applied in a high power railway traction driven system;experiment results prove the validity of the propsed control strategies.