Advanced Materials Research Vols. 655-657

Abstract: A control strategy for a fault-tolerant paralleling active power filter was proposed. The structure and running models of the fault-tolerant paralleling active power filter were given. When the inverter of APF had fault in some phase, the fault structure of the inverter was analyzed. Its fault-tolerant structure was three-phase four-switch. The bridge composed of two capacitors replaced the fault phase for the inverter based on three-phase four-switch. It was important to stay stable for inverter DC-side. The method to stabilize the DC-side voltage was proposed. The controlling strategy for APF working on both normal state and fault state was proposed. The simulating results showed that harmonic currents were suppressed by the fault-tolerant paralleling APF whether working on normal state or fault state. The DC-side voltage stayed stable and the system has high reliability.

Abstract: In order to meet the needs of different occasions for the low power photovoltaic grid-connected inverter, designed a single phase 3KW two stage photovoltaic grid-connected inverter. DC - DC link used an improved ZVT- Boost circuit to achieve maximum power point tracking (MPPT) control of the panels, DC-AC link used frequency doubling unipolar SPWM control to ensure the full-bridge inverter circuit output current waveform distortion rate minimum, at the same time to achieve the highest efficiency.

Abstract: Al wire bonding lift-off and solder delamination are the main failure modes of IGBT module. When the severity of the failure mode is different, the temperature character of IGBT is also different. This paper presents a methodology based on 3D electro-thermal coupling finite elements modeling intended to analyze the relation between the failure degree and the temperature, and compares the influence degree of two kinds of failure modes to the performance of IGBT module. The results suggest the bonding lift-off has more influence than the solder delamination on the same load and boundary conditions. This method and the corresponding results help to evaluate these failure modes how they influence the performance of IGBT, determine the failure, establish the failure standards and find the optimization of structure design.

Abstract: In order to improve the output power of laser pulse in the inertia confinement fusion experiment, an arbitrary waveform generator is fabricated to shape the laser pulse. The arbitrary waveform generator is based on the impedance tapered micro-strip line technology and GaAs Field Effect Transistor set which has a good ability of generating voltage-controlled current. With the impedance tapered micro-strip line technology, the arbitrary waveform generator generates shaping electrical pulse with duration less than 10 ns, 330 ps time-domain adjustment. We use the shaping electrical pulse to modulate semiconductor laser which has the characteristic of direct modulate, the experiment results show the shaped laser pulse is obtained based on the shaping electrical pulse.

Abstract: This paper presents a method small TEC temperature control system that is based on photovoltaic power generation technology. And their working principles are analyzed, and equivalent circuit diagrams are given at different working mode, at last simulation and experimental results are presented to verify the fact that the principle is correct.

Abstract: In this paper, through theoretical analysis, find out the cause of formation of the infrared camera critical flicker problem and the relations of the internal switch structure, and through the circuit structure, the ways and specific measures are presented to solve the infrared camera critical flicker problem.

Abstract: Three-level is widely applied in the high-power medium-voltage system and in which SVPWM algorithm is the key part. While the three-level algorithm can be simplified into two-level space-vector modulation algorithm based on reference voltage decomposition, it makes the application that active area vector on three-level to be a probability. It breaks the three-level allocation time down into two-level and the inherent relationship between the active area vector and the traditional SVPWM algorithm is analyzed. Non-midline current direction detection method is used in neutral point potential control of active area vector method for three-level. Simulation and experimental results verify the availability of the novel methodology.

Abstract: This paper introduces the principle and realization process of multi-channel data acquisition and storage system based on FPGA, A/D converter, FLASH and USB microcontroller. The system’s controlling core is FPGA. FPGA finished the switch of the multi-channel analog switch、A/D conversion、data compilation and storaging in the FLASH and uploading the data to PC by USB microcontroller. Test result can indicate that the system is simply and practical .The system can finish the real-time acquisition and processing for 12 input signals, sampling rate up to 1MSPS.

Abstract: The dual-loop control method, in which inner-loop is the current and outer-loop is the voltage, is proposed to design a high-efficient precise numerical control parallel power supply system, it operates at input voltage of 24V, output voltage of 6-12V and output current of 0-4A. The current ratio of the parallel circuits can be set arbitrarily. Precise adjustment of output current and improvement of efficiency are realized by width modulation and synchronous buck-topology switching power supply, the output current error is smaller than 20mA and DC-DC conversion efficiency is up to 90%; to make output voltage error smaller than 30 mV and the current-sharing error smaller than 0.5%, digital calibration technology and PID control algorithm are used. In addition, this system is equipped with the function of overload protection, double-source redundant heat standby and turn-off, etc.

Abstract: This paper studies a very simple structure for dual-band bandpass filter. Filter is composed of two asymmetric coupled resonator circuit by two sets of different size stepped impedance resonator. This circuit applied microstrip line, coupling principle and impedance ratio by controlling the stepped impedance resonator to control the center frequency 2.6/5.2 GHz of the first and the second bandpass filter. The basic structure of the filter is constituted by the three sections of transmission line and two sets of SIR, that is, in two gaps of the three sections of transmission line parallel connection the equivalent inductances and capacitor of the two sets of SIR in series with the resonant circuit (LCL) to constitute bandpass filter. The low frequency 2.6 GHz is through the upper half of low impedance SIR, and the high frequency 5.2 GHz is through the lower half of high impedance SIR. This paper presents the design of asymmetric SIR-based dual-band bandpass filter, the filter structure is simple, easy to produce and can control the characteristics of the passband center frequency. By electromagnet simulation software( IE3D ) to simulate, the actual production of the circuit using a vector analyzer measurement, simulation and measurement results show good consistency.