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The instantaneous power for a three-phase rectifier can be calculated directly in the orthogonal coordinate system via coordinate transformation. However, it is difficult to calculate the instantaneous power directly for a single-phase rectifier due to the lack of another phase. Therefore, an orthogonal signal generator (OSG) is required to create an orthogonal coordinate system. Currently, conventional OSG algorithms suffer from long response time. To remedy this problem, in this paper, an arbitrary phase-delay OSG algorithm is developed and applied to the direct power control (DPC) system in the single-phase rectifiers. First, the instantaneous power theory and DPC are presented. Then, the principle of the arbitrary phase-delay OSG method is introduced and the anti-interference ability of the proposed method is analyzed. Through the dynamic response analysis, the developed algorithm brings faster response, easier implementation, and less computational burden compared with other common OSG algorithms. Finally, the validity and advancement of the proposed algorithm are verified by simulations and hardware-in-the-loop experimental tests. A comparison with conventional OSG algorithms also proves the advantages of the developed method.

Traditional current control methods for a single-phase rectifier in an electric traction drive system suffer from either long response time or nonzero steady-state error. A novel current vector control strategy in stationary-frame is therefore proposed, in this paper, to improve the control performance of a rectifier. The mathematic model of the single-phase two-level pulse rectifier was first analyzed by complex space vector. Then, the principle of the proposed current control method was described. Based on this, the implementation and parameter tuning method of the current control algorithm based on a space complex vector in a two-phase stationary coordinate system are presented. Moreover, two kinds of general current control algorithms are analyzed and compared with the proposed algorithm to demonstrate the advantages of the proposed algorithm. The proposed control scheme absorbs advantages of the conventional control schemes, including fast response, zero steady-state error, and active and reactive power independent control, but overcomes their shortcomings. Finally, the theoretical analysis is verified by means of simulation as well as a hardware-in-loop experimental test on an experimental laboratory setup and some comparisons with conventional current control algorithms prove the advantages of the utilized method.

With the increasing number of electric multiple units (EMUs) operating in a rail depot simultaneously, low frequency oscillation (LFO) may occur. In this paper, linear active disturbance rejection control (LADRC) is designed for the single-phase EMUs rectifier control. Moreover, Nyquist criterion is adopted to analyze the stability theoretically. Furthermore, the static and dynamic performance of the system based on LADRC is verified through the resistance mutation tests in MATLAB/Simulink comparing with traditional proportional integral (PI), nonlinear PI (NPI) and auto disturbance rejection error PI (ADRE-PI). Finally, the validity of the LFO suppression with LADRC is verified in the simulation.

An increasing number of high-speed trains are put into operation in China, whose current harmonics from grid-side converter (GSC) are introduced into the traction power supply network. However, the traditional linear time-invariant (LTI) modeling of grid-side converter makes it difficult to analyze the current harmonic characteristic and coupling phenomenon because of the power switching devices and the nonlinear controller. In this paper, the linear time-periodic (LTP) system modeling method is employed to investigate the single-phase GSC applied in CRH3 electric multiple units. The harmonic transfer function (HTF) small signal model of the GSC is derived after local linearization and investigated to analyze the harmonic interaction in frequency domain and the steady-state response in time domain. At last, the nonlinear simulation results are represented to verify the effectiveness of the HTF harmonic analysis.