Qian Zhao-ming

Magamp post regulation for LLC series resonant converter with multi-output

Strategy of time-sharing is adopted in LLC resonant converter with multi-output for increasing the adaptability of the very topology to such application as multi-output with requirement of high regulating ratio, meanwhile strategy of magamp post regulation is applied by adding two saturable inductors in secondary output ends as well. Principle of influence generated by dead time of magamp involved in LLC resonant converter on regulating ratio, is analyzed in detail. That influence of problem of dead time existing in magamp in flyback converter is much worse than in LLC resonant converter is verified both by principle analysis and experimental result. An experimental prototype of 310 V input, 24 V/3 A and 12 V/2 A outputs, whose full load efficiency reaches 88.5%, is built to verify achievement of ZVS at full range and the wonderful cross regulating ratio

Status of electromagnetic compatibility research in power electronics

Recent development and research trends related to the EMC/EMI issues in power electronics system are reviewed. Research activities on EMI characterization of power converters, the EMI power filter design, EMI suppression techniques for drive system and switching power supply, PCB layout, EMI modeling and simulation for power electronics systems are discussed separately in different sections.

Analysis and Research of a Multiple-loop Control Strategy for Single-Phase UPS Inverters

This paper presents the analysis and research of a fully digital control design for a multiple-loop regulation of single-phase inverter. The digital control scheme incorporates an inner fast current loop with an outer slower voltage loop to eliminate the weakly dumped poles of the output LC filter. The inner current loop is added to improve the performance of transient response and decrease THD content. The output voltage and load current compensation are also added in the scheme to improve the performance and robust of system. The control system is implemented on DSP TMS320LF2407A. Both the simulation and experiment results show that the DSP-based multiple-loop controlled inverter can achieve excellent performance, and the multiple-loop control strategy is good for the control of inverter

A novel hybrid active power filter with two passive channels for high power application

This paper proposes a new structure of serial hybrid active power filter which can reduce the power rating of the active power filter dramatically, and has good performance for harmonic suppression. The principle and designing rules are analyzed. The proposed structure is rational and feasible for high kVA applications. Simulation results are presented too.

The design and implement of series hybrid active power filter for variable nonlinear loads

The paper discusses the design and implementation of a series hybrid active power filter (SHAPF) when its nonlinear load is varied in a wide range. The specially designed passive filter and adaptive control methods of SHAPF are discussed. With these methods, the SHAPF is stable with good performance and causes small capacitive reactive current. The simulation and experimental results are accorded with the theoretical analysis.

A novel average model for a single stage PFC converter

A novel average model for a single stage PFC converter is given. Voltage control mode, peak current control mode and average current control mode can be simulated easily by changing the parameter of an average model. It can be used to do large signal analysis, small signal analysis, static analysis and dynamic analysis. By using this average model the simulation speed can be improved by 2 orders compared with using a conventional switched model. It can be applied to optimize the trade-off between high power factor, voltage stress, current stress and good output performance while designing a single stage PFC converter. A 60 W single stage power factor corrector is built to verify the proposed model.

A Fully Digital Controlled 3KW, Single-Stage Power Factor Correction Converter Based on Full-Bridge Topology

This paper deals with a 3 KW power factor correction (PFC) circuit based on the isolated full-bridge (FB) converter. The operation principle of the very converter is simply analyzed. Digital design consideration based on the small-signal dynamic modeling of the isolated PFC converter is specified in this paper. Implementation strategy and cost effectiveness of digital control for the single-stage PFC converter are studied. A transformer is used to provide galvanic isolation enables a wide range of output voltages, either lower or higher than the input voltage, allowing multi-output solutions. The adopted digital control strategy features fast dynamic response and excellent steady regulation characteristic without multiplying the input feedforward. High power factor and high efficiency are both achieved by combining FB main circuit and digital control. That flexibility is greatly increased can further contribute to system integration research on distributed power system. Without multiplying the input feedforward, fast dynamic can be achieved due to the flexibility of digital control strategy. The above excellent performances are verified by an experimental prototype, whose output power is 3 KW and PFC operating frequency is 110 K

A hybrid solution to active power filter for the purpose of harmonic suppression and resonance damping

Active power filters (APFs) have been intensively explored over the past decade. Various topologies and control schemes have been documented aiming at reducing the cost and improving the performance of the harmonic compensation system. This paper highlights the essence of the mechanisms of diverse APFs by using the concepts of controllable sources. Four basic active units for comprehensive APFs can be employed in the circuit branch to control the impedance of the branch. This paper also presents a general principle for constructing new hybrid APFs to suppress harmonics. The principle can be easily used to find new approaches for cost-effective hybrid APFs. One hybrid solution is provided in this paper.

A novel active power filter for high voltage application

A new active power filter (APF) is proposed in this paper which combines the two mechanisms of harmonic tracking and cancellation as well as variable resistance. This strategy greatly reduces the requirement of the passive filter. A shunt resonant passive filter, which falls in resonance in the fundamental frequency and 6/sup th/ harmonics, is employed in this paper mainly to reduce the fundamental current loss of the HAPF. Simulation results demonstrate that the system can suppress harmonics from 2th to 20th with more than 20 dB attenuation and 10 Hz-30 Hz with approximately 20 dB. The HAPF expands the pass-band width of the PF, while demonstrates high impedance at fundamental frequency.

A parallel front-end LCL resonant push-pull converter with a coupled inductor for automotive applications

A parallel technique with a coupled inductor is proposed for an LCL resonant push-pull converter. The coupled inductor is inserted in the front of the common resonant capacitor of two parallel push-pull converters, sharing the current of the two converters. The equivalent circuit and state equation of the proposed converter is described, and then the effects of the mismatch of the equivalent resistor and leakage inductor on sharing current is derived. The controller of the cascaded full-bridge inverter is presented. Experimental results of a 2kW inverter showed that the current difference of the two parallel units is less than 2%.