Research On High Performance Current Control Algorithms For Single-phase PWM Rectifiers

Single-phase PWM rectifiers have been widely used in railway locomotive traction,static reactive compensation,uninterruptible power system,active power filtering due to these advantages,such as bidirectional energy flow,unity power factor,and constant DC-link voltage.With the development of power electronics technology and devices,the single-phase PWM rectifiers require faster dynamic response and better steady-state performance under the fluctuation condition of the line voltage to satisfy the improvement of power quality requirements.Therefore,it is valuable for theory research and engineering design that this paper focuses on high performance current control algorithms for single-phase PWM rectifiers.In order to improve the dynamic response of DQ current decoupling control,increase the control accuracy,achieve the unity power factor,eliminate adverse effects under the fluctuation condition of the line voltage,and reduce hardware cost of single-phase PWM rectifiers,this paper focuses on the virtual orthogonal component construction algorithm,the inductance parameter sensitivity analysis,the inductance error on-line compensation,the virtual voltage flux-linkage observer.The specific contents are listed as follows:Firstly,the topology and principle of single-phase PWM rectifiers are analyzed,and its mathematical model in the two-phase rotating d-q coordinate system is established.The basic principles of the DQ current decoupling control method is introduced.Meanwhile,the advantages and disadvantages of this method are also discussed.Secondly,in order to generate the virtual orthogonal component of rotational coordinate transformation in single-phase system applications,the traditional quarter-cycle delay algorithm and the second-order generalized integrator(SOGI)algorithm are analyzed.The DQ current decoupling control algorithm based on virtual signal feedback(VSF)for single-phase PWM rectifiers is investigated.In addition,the inductance parameter sensitivity analysis is discussed.The VSF algorithm can bring perfect steady-state performance and rapid dynamic response for the current controller.Then,an inductance error on-line compensation algorithm based on the steady-state q-axis current offset is provided to eliminate the undesirable effect on power factor due to inductance mismatch.Meanwhile,compared with the traditional quarter-cycle delay algorithm and SOGI algorithm,the proposed algorithm and the traditional algorithms are verified in computer simulations.Thirdly,in order to eliminate adverse effects under the fluctuation condition of the line voltage and reduce hardware cost of rectifiers,the virtual flux-linkage observer of single-phase PWM rectifiers without the line voltage sensor is studied.This algorithm is similar to the observation of the flux-linkage in the AC motor.As a result,the line voltage sensor is eliminated by the construction of the virtual flux-linkage vector.Meanwhile,this algorithm is verified in computer simulations.The simulation results show that the algorithm can get the angle signal for coordinate transformation without sampling the line voltage,and achieve the goal of unity power factor for single-phase PWM rectifiers without the line voltage sensor.Finally,a hardware-in-the-loop experimental platform of single-phase PWM rectifiers based on the RT-LAB real-time simulator and the TMS320F28335 DSP digital controller is designed.The DSP program of the virtual signal feedback algorithm and the inductance error on-line compensation algorithm are completed.Meanwhile,two kinds of algorithms are verified in experimental tests.The experimental results show the effectiveness and correctness of the proposed algorithms.