Changsheng Hu

A novel RPV (reactive-power-variation) anti-islanding method based on adapted reactive power perturbation

In this paper, a novel reactive-power-variation (RPV) method of distributed generation (DG) inverter is presented. The proposed RPV method detects PCC frequency and outputs the minimum reactive variation which can just deviate the frequency of PCC to the frequency thresholds decided by the utility standards when the islanding condition happens. Compared with the traditional bilateral RPV method, the proposed method can detect islanding condition without NDZ and reduce the perturbation of reactive power significantly in comparison with the traditional bilateral RPV method. Experimental results with a three-phase 30kW inverter are provided to verify the proposed method.

High-surety Microgrid: Super Uninterruptable Power Supply with Multiple Renewable Energy Sources

Abstract A high-surety microgrid—the super uninterruptable power supply—is introduced systematically in this article. Renewable energy, such as fuel cells, photovoltaic, and natural gas, are introduced in the super uninterruptable power supply to improve its reliability. First, the best architecture for the super uninterruptable power supply is selected according to the architecture performance evaluation. Second, the reliability and cost models are built to compare the super uninterruptable power supply with the traditional uninterruptable power supply. Highly reliable power distribution and power management algorithms are introduced based on the characteristics of multiple sources. Then the system stability is analyzed based on the impedance model of the super uninterruptable power supply. A highly reliable power conversion system is introduced, including redundant design and short-circuit protection. Finally, the experimental platform and experimental results are provided to verify the concept of a super uninterruptable power supply.

A High-Efficiency Single-Phase AC/DC Converter With Enabling Window Control and Active Input Bridge

The conventional continuous conduction mode boost converter has been widely used for power factor correction (PFC) applications because of its high input power factor and simplicity, but it suffers from conduction loss in the input rectifier bridge and switching loss due to the high switching frequency. The efficiency decreases significantly under the low input voltage or the light-load work condition. In this paper, a novel enabling window control (EWC) method is introduced to reduce the switching loss, and an active input bridge is used to replace the traditional diode bridge for high efficiency. The proposed EWC method is easy to implement with existing PFC ICs, and only a few additional control components are needed. Moreover, electromagnetic interference noise and driving loss of the main switch can be reduced with the EWC method. Semiconductor devices with competitive price can be used to reach efficiency as high as SiC diode and Cool-MOSFETs. A self-driven circuit is also used for the active bridge. The principle and design of proposed method are presented and the validity of the proposed method is verified by experimental results obtained from a 500-W prototype.

HID lamps with electronic ballast

In this paper, the start-up characteristics of automotive HID lamps with electronic ballast is investigated. In order to prevent the lamp from extinguish immediately after break-over, auxiliary current circuit is proposed to provide additional current to lamp. During warm-up or run-up phase, DC lighting period also is needed to light a discharge lamp more reliably at the starting time of the discharge lamp. Experiments have been carried out to verify the function of these two proposed solution.

LCLC resonant converter for multiple lamp operation ballast

This paper presents a design methodology, analysis, and practical considerations of LCLC resonant converter for multiple lamp operation ballast. According to the basic requirements of multiple lamp operation ballast (MLOB), the design procedure can be outlined to determine resonant parameter. Consequently, independent MLOB can be achieved under voltage-source half-bridge LCLC resonant converter with zero voltage switching (ZVS). Finally, some experimental results obtained from a prototype are shown to verify the theoretical discussion.

Interleaved Flyback Micro-inverter with SiC MOSFET

In this paper, we discuss the interleaved Flyback Micro-inverter with SiC device. The Micro-inverter is composed of front-end interleaved Flyback converter and a 50Hz switching MOSFET inverter. A loss model is used to compare the efficiency between using SiC devices and conventional device. Three solutions are compared: Micro-inverter with Si diode, Micro-inverter with SiC diode, and Micro-inverter with SiC MOSFET for synchronous rectifier. Finally the comparison is verified by experiment.

High efficiency PFC with Enabling Window Control and active input bridge

Conventional CCM Boost (CB) PFC has been widely used for the PFC applications because of its high input power factor and simplicity, but it suffers from conduction loss in the input rectifier bridge and switching loss due to the high switching frequency. The efficiency decreases significantly under the low input voltage or the light load work condition. In this paper, a novel Enabling Window Control (EWC) method is proposed to reduce the switching loss, and an active input bridge is used to replace the traditional diode bridge for high efficiency. The principle and design of proposed method is presented, furthermore, the validity of the proposed method is verified by experimental results obtained from a 500W prototype.

Analysis and design of igniter for HID ballast

This paper describes the operation principle, effects of design parameters and critical design issues related to igniters used for the ignition of metal halide lamps. Mathematical modeling for the circuit is also given. The relationship between the width and peak value of igniter pulse and the circuit parameter is deduced. Experiments have been carried out to verify the theoretical analysis.

Analysis of the voltage feedback self-oscillating electronic ballasts

In this paper, control model of voltage feedback self-oscillating ballast is established based on the point of view of control system. Two operation modes are proposed to analyze the self-oscillating operation. It can be found that this method can precisely calculate the probable self-oscillating frequency and determining its stability. The design is implemented successfully in a 36 W fluorescent lamp system. The experiment results prove that these methods are useful in the design of self-oscillating ballast.

Unified control scheme design for both the PWM rectifier and the inverter in the uninterruptible power supply (UPS) system

This paper first discusses control loop characteristics for the PWM rectifier and the inverter used in an on-line UPS system. Then a unified control scheme for both the PWM rectifier and the inverter in the UPS system is investigated using single phase control in ABC frame. Based on the unified control scheme, a generic control kernel is defined. This generic control kernel is used to realize the main performance of the UPS system, such as dynamic response, low THD and synchronism. Then the generic control kernel can be further applied to both the PWM rectifier and inverter by selecting different inputs. The unified control scheme not only significantly simplifies the UPS control software development, but also improves its maintenance. Finally, this unified control scheme is verified on a 50kVA UPS system.