Two-way Energy Flow Research Articles

Full Power Experiment Method of Single-Phase PWM Back-to-Back Converter

Based on the single-phase H-H power unit topology in the novel co-phase power supply system, with the back-to-back grid-connected operation method, this paper aimed at solving the problem that in experiment, system capacity constraints caused the failure to achieve unit full power output and proposed the strategy of rectifier voltage, current double closed loop and full disturbance feed-forward control. Finally, based on the digital signal processor (DSP) and complex programmable logic device (CPLD), this study constructed a hardware platform of the power unit control system. Experimental results show that the system is stable, achieving two-way flow of energy.

Research on the Topology and Control Policy of Composite Energy Feedback Cascaded Multi-Level Inverter

Traditional uncontrolled or phase controlled cascade multilevel inverter only can realize one-direction transmission of energy. This paper presents a complex energy feedback cascade inverter topology with full-controlled, phase controlled Power units and its control strategy. For the full-controlled units, use PWM converter to replace the traditional rectifier bridge, and then combine with H-bridge inverter, the two-direction inverter is realized. The others remain phase controlled structure. According to the pump-up voltage in the energy feedback process ,a new method using the output side DC voltage closed loop control is proposed to prevent DC voltage shock and make all energy feedback to grid .Then it was verified in a cascade inverter with five units in which only three units are full-controlled. This inverter has the merits that it can automatic realize two-way flow of energy, the input currents approximate sine, the DC voltages control stability, the output voltage waveform is good and the phase shifting transformer structure is also simplified, etc. Simulation showed its feasibility and effectiveness.

Improving energetics in an ideal baroclinic instability case with a Physical Conserving Fidelity model

To improve the energetics in the life cycle of an ideal baroclinic instability case, we develop a Physical Conserving Fidelity model (F-model), and we compare the simulations from the F-model to those of the traditional global spectral semi-implicit model (control model). The results for spectral kinetic energy and its budget indicate different performances at smaller scales in the two models. A two-way energy flow emerges in the generation and rapid growth stage of the baroclinic disturbance in the Fmodel. However, only a downscale mechanism dominates in the control model. In the F-model, the meso- and smaller scales are energized initially, and then an active upscale nonlinear cascade occurs. Thus, disturbances at prior scales are forced by both downscale and upscale energy cascades and by conversion from potential energy. An analysis of the eddy kinetic energy budget also shows remarkable enhancement of the energy conversion rate in the F-model. As a result, characteristics of the ideal baroclinic wave are greatly improved in the F-model, in terms of both intensity and time of formation.

Study of New Three- phase Voltage Source PWM Rectifier

It has been established that a mathematical model for the three-phase voltage source PWM rectifier based on the three-phase stationary symmetric coordinate system (a, b, c) and two-phase synchronous rotating coordinate system (d, q); adopted the power feedforward decouping control strategy, a double closed-loop control structure for three-phase voltage source PWM to solve the problem between the active and reactive power coupler. At last, the Space Vector PWM (SVPWM) control strategy has been put forward, which improved the utilization of DC voltage and robustness of the system. The simulation and experiment results show that the system which was designed has good waveform of AC side current, high stability, fast dynamic response speed, and can achieve the two-way flow of energy and the control of unit power factor.

Research on a New Type of Energy Feedback Cascade Multilevel Inverter System

Traditional cascade multilevel inverter can only transmit one-direction of energy. This paper proposes a new cascade multilevel inverter topology and control strategy based on part units to realize the energy feedback. By using PWM converter to replace uncontrollable converter in part units of the traditional inverter, and combining the inverter with H-bridge inverter, the two-direction running of the cascade inverter is realized. A double closed loop control strategy is used to obtain fine control characteristic of input current. The carrier phase-shifted SPWM technology is adopted in the cascade inverter to reduce harmonious wave of output voltage and current, meanwhile, a new type of bypass control method is proposed to collect all the feedback energy and restore it into the energy feedback units. According to the simulation of a three-phase and five-unit cascaded inverter with three energy feedback units, the results demonstrate that the proposed inverter can be input near sinusoidal current , and realize two-way flow of energy automatically with simplified phase shifting transformer structure, and show its feasibility and effectiveness. DOI: http://dx.doi.org/10.11591/telkomnika.v11i1.1864

Design and Simulation of the New Three-Phase Voltage Source PWM Rectifier

Based on the principle of the three phase voltage source PWM rectifier, firstly, describes the topology of the three-phase VSR, and establishes the three-phase VSR’s mathematical model based on the three-phase stationary symmetric coordinate system (a,b,c) and two-phase synchronous rotating coordinate system (d,q); then analysis the three-phase VSR’s control strategy, and discusses the feedforward decoupling control strategy of the inner current loop, the outter voltage loop control strategy and the Space Vector PWM (SVPWM) control strategy. Secondly, builds a simulation model, simulates it in Matlab\Simulink environment.The simulation results show that the system has good current waveform of AC side current, high system stability, fast dynamic response speed, and can realize two-way flow of energy, energy feedback, and unit power factor control.