Wang Zhao-an

Study on the Influence of Supply-Voltage Fluctuation on Shunt Active Power Filter

Is there any influence of supply-voltage fluctuation on the shunt active power filter? Few papers have discussed this problem. In this paper, based on the instantaneous power balance of shunt active power filter ac-side and dc-side, a small-signal model of dc-link voltage control is derived. According to this small-signal model, the influence of supply-voltage fluctuation on the dc-link voltage of shunt active power filter is analyzed in detail. The conclusion is that the supply-voltage fluctuation has influence on the dc-link voltage of shunt active power filter. Then a feedforward control method of supply-voltage and compensation current is proposed to eliminate the influence. The proposed feedforward control method can be easily implemented in practical. In this paper, the influence of supply-voltage fluctuation on compensation performance of shunt active power filter is also analyzed when the dc-link voltage is constant. From the analysis, it can be concluded that current controller with PI regulator has better performance to suppress the influence of the supply-voltage fluctuation. Finally, the experimental results are given to demonstrate the conclusions.

Design of Boost-Flyback Single-Stage PFC converter for LED power supply without electrolytic capacitor for energy-storage

Light emitting diodes (LEDs) are likely to be used for general lighting applications due to their high efficiency and longer life. This paper presents the concept of applying large voltage ripple for energy storage into the Boost-Flyback Single -Stage PFC converter for the elimination of the electrical capacitor. Following proposed design procedure, the single stage PFC circuit with small energy storage capacitance can still achieve good output voltage regulation while preserving desired input power factor. The detailed theoretical analysis and design procedure of the Single-Stage PFC converter is presented. The experimental results obtained on a 60W prototype converter along with waveforms are presented.

A control approach for detecting source current and series active power filter

The basic operation principle of the series active power filter for compensating the voltage type harmonic source was analyzed. A control approach for detecting source current, based on the instantaneous reactive theory, was studied for the APF to obtained the reference signal. In addition, the control methods of PWM inverter and its DC side voltage were proposed. A prototype was manufactured according to them and corresponding experiments were done to show the compensation effect on the voltage type harmonic source. The results prove the validity of the proposed control approach for detecting source current and indicate that the series active power filter adopting it has the good compensation characteristics of harmonics.

Study of Control Methodology for Single Inverter Parallel Connected Dual Induction Motors Based on the Dynamic Model

In this paper, a complete close loop system was designed based on the dynamic model. Then, the method proposed in this paper was demonstrated to have a good dynamic characteristic on torque response which was thought to be important in railway traction system. Finally, we improved the performance during the process from unbalanced loads to balanced loads by decreasing the systems sensitivity to some differential quantities when they converged to zero. The validity and effectiveness of this proposed method were confirmed through different unbalanced load tests of simulations and experiments.

Design of A New DC Link Voltage Controller for Universal Power Quality Controllers

In this paper, an outer loop model for DC link voltage control in a three-phase three-wire universal power quality controller (UPQC) is proposed based on the equilibrium of instantaneous power in parallel active power filter. According to the small signal model, a new controller for DC link voltage control has been designed. It is expected to improve the system performances in both reference following and disturbance suppression. Computer simulations and hardware prototype experiments demonstrate that compared with conventional P controller and PI controller, this new controller has better performances for DC link voltage control and guarantees a good compensation while voltage sags occur in the power supply.

An instantaneous detecting approach of harmonic voltage for the series active power filter

In this paper, based on the instantaneous reactive power theory, an instantaneous detecting approach of harmonic voltage is proposed. It is discussed both theoretically and experimentally that the harmonic voltage can be obtained in real-time through detecting load voltage. The distinguishing points of the presented approach are its fast response and accuracy. It is convenient to implement by using analog multipliers, dividers and operational amplifiers. The experiment results verify the correctness and feasibility of the proposed approach, and it can be used for active power filters to compensate power system harmonics.

A Novel Control of Series Active Power Filter without Harmonics Detection

The main idea of conventional control methods for series active power filter (SAPF) is to control the SAPF as frequency-selective impedance or voltage source. In these conventional control methods, a real-time instantaneous harmonics detection algorithm is essential and comparatively complex, which is usually implemented with a digital signal processor (DSP) therefore makes the control circuit complicated and high cost. Furthermore, the time delay caused by the harmonics detection and its digital implementation will deteriorate harmonics compensation performance. In this paper a new control method for SAPF is proposed. The idea of the proposed control is to control the compensation voltage injected by SAPF to trace the multiple of whole line current to achieve current harmonics suppression. Since the control reference signal directly utilizes the detected line current without calculating harmonics, the proposed control actually eliminates the harmonics detection process. In addition, the DC-side voltage control is indispensable in this control to maintain the active power balance for the proper operation of the SAPF system. Compared to traditional control methods, the proposed control is therefore much simpler and easier to implement at low cost. And the time delay caused by complicated harmonics calculation does not exist any more. Simulation and experimental results are presented to verify the validity of the proposed control method and the performance of the SAPF.

Analysis and Elimination Method of the Influence of Supply Voltage Fluctuation on Shunt Active Power Filter Dc-link Voltage

Is there any influence of supply voltage fluctuation on the shunt active power filter? Few papers have discussed this problem. In this paper, based on the instantaneous power balance of shunt active power filter ac-side and dc-side, a small signal model of dc-link voltage control is derived. According to this small signal model, the influence of supply voltage fluctuation on dc-link voltage of shunt active power filter is analyzed in detail. And the conclusion is that the supply voltage fluctuation has influence on dc-link voltage of shunt active power filter. Then a feedforward control method of the supply voltage and the compensation current is proposed to eliminate the influence in this paper. Finally the experimental results also are given to demonstrate the conclusions.

Parasitic Parameter Extraction and Loss Analysis of A 3kW MOSFET Hybrid Integrated Power Electronics Module (IPEM) for Three-phase Motor Driver

The paper presents the system configuration and 3D hybrid packaging of a 3kW IPEM in detail. The interconnection parasitic parameters RLC matrices of each phase leg in the inverter have been extracted by simulation, which are validated by experimental result. And the loop impedance for each phase leg has been analyzed versus the loop current frequency, which impacts the ringing frequency. Based on the steady state experimental result, the model of conduction loss and switching loss for the phase leg have been analyzed and deduced. The new measurement method on conduction losses and switching energy for each phase leg has been introduced, and the experimental data prove the availability of the method. Finally, paper gives the IPEM experimental result under SPWM modulation, which indicates that the losses model is coincident to the experimental losses and IPEM has high efficiency above 80 percent with light load.

Study of Speed Sensorless Control Methodology for Single Inverter Parallel Connected Dual Induction Motors Based on the Dynamic Model

In this paper, a complete close-loop speed sensorless dual-motor drive system was designed based on the dynamic model and an adaptive observer which is based on MRAC was applied to each induction motor, in which stator fluxes, rotor fluxes and motor speeds were estimated. The validity and effectiveness of this proposed method were confirmed through different balanced and unbalanced load tests of simulations