Applied Mechanics and Materials Vols. 241-244

Abstract: The pulsed power is an important part of the airborne geophysical method detection systems. However, the traditional method of aerial transient electromagnetic transmitted waveform will cause the interference which is not conducive to process the post-data. The paper presents a new kind of dual polarity triangle pulse power device. The experimental results verify the correctness of theoretical analysis by using constant voltage clamping method to achieve emission of the isosceles triangular current pulse. Its falling edge of high linearity, high reliability, the output characteristics of a good anti-interference ability.

Abstract: Phase locked loop pulse interpolation technique requires for the input pulse signal frequency multiplication processing. With FPGA as the core, by detecting the edge of the input pulse signal the separate frequency factor was generated, then frequency division of the system clock was realized according to the separate frequency factor, thus phase locked loop frequency multiplication processing of the input pulse signal was completed. The simulation results show that this method has the advantages of high precision and short frequency response time, etc.

Abstract: Electric vehicle (EV) charging & swapping station is an indispensable EV energy service infrastructure after the large-scale industrialization of EV. Power line carrier communication (PLC) is a technology that transmits analog or digital signal with high speed through the carrier. By applying robust and reliable power line as the transmission medium of carrier signal, PLC is featured with stable and reliable information transmission, reasonable routing, no re-wiring, wide coverage, convenient connection, and highly reliable channel. This paper briefly describes the characteristics and applications of PLC technology, introduces functions and an overall design plan for the communication network of EV charging and swapping stations. Meanwhile, it provides the hardware realization and protocol establishment of communications network interfaces for PLC-based EV charging and swapping stations as well as a design for information management system.

Abstract: As the critical process in battery production, formation is related to the quality of battery and directly affects production cost. A low voltage, high current DC/DC converter is designed for large capacity lithium battery formation equipment. Design of basic topological structure, feedback module and peripheral steering circuit are introduced. Besides, design of PWM driving circuit and parameters of high- frequency transformer are presented in detail. This two-way DC/DC converter has features of high stability, high reliability, small size, light weight and its efficiency of buck-boost can be up to 84% and 83% respectively.

Abstract: In interconnected systems, the low frequency oscillation becomes an important factor that affects the power system stability and limits power transport. This paper analyses the principle of low frequency oscillation in power system and the measures on suppressed low frequency oscillation, at last discusses the future development.

Abstract: Theoretical line loss calculation is the basis of line loss analysis and decision-making in loss reduction. Due to technical constraints in the past, traditional theoretical line loss calculation method uses a large number of simplified calculations. This paper proposes a new online method of line loss calculation in distribution networks which is based on PQU (active power, reactive power and voltage) load curves. The proposed method has a large amount of data operation and thus can accurately reflect the load variation with time. Based on a new kind of metrical equipment and the proposed method, the assistant decision system for comprehensive power loss reduction of rural power network has been developed and has been tested on several rural power networks. The results show its convenience, accurate calculation and high efficiency.

Abstract: Theoretical line loss calculation is the basis of making line loss analysis and loss-reduction decision. Due to technical constraints in the past, traditional algorithms on theoretical line loss calculation used a large number of simplified calculations. This paper proposes a new online method of line loss calculation in distribution networks which is based on PQU (active power, reactive power and voltage) load curves. Based on a new kind of metrical equipment and the proposed method, the power loss calculation system has been developed and has been tested on several rural power networks. The results prove that the method improves the assumptions of traditional algorithms and calculation precision.

Abstract: A systematic introduction to principles and advantages of the class-D audio amplifier based on pulse width modulation (PWM) are presented in this paper. The traditional sawtooth generator needs voltage-regulator tube to server as a core component. Against to such a disadvantage a simple way based on the charging and discharging capacitance is proposed to achieve sawtooth generator. The circuit design is based on SIMC 0.18um process. Spectre simulation results show that the sawtooth generator's performance is good. And it suits for the design of class-D audio power amplifier chip.

Abstract: A novel V-shaped microstrip meander-line slow-wave structure was investigated to expand the operating bandwidth. The high frequency characteristics of V-shaped structure and traditional N-shaped and U-shaped structures were analyzed by electromagnetic simulation software HFSS, and the effects of different structural parameters on the high frequency characteristics were studied. The results show that the V-shaped structure provides better performance in operation bandwidth and interaction impedance than traditional structures, and when the dielectric rod replaces the dielectric slab the performance further improves.

Abstract: This paper presented an adjustable analog predistortion linearization method for RF power amplifier. The linearization includes an attenuator, a phase shifter and an anti-parallel Schottky diode pair with DC bias, through adjusting these components, we can adjust predistortion characteristic of the linearization to be complementary to distortion characteristic of RF power amplifier. By cascading this linearization with power amplifier, we can improve linearity of amplifier. Firstly, we simulated the proposed predistortion linearization with software ADS, then the linearization was manufactured and tested together with RF power amplifier PTF080551. Experimental results show that we can adjust predistortion characteristic of the linearization to be closely complementary to distrotion characteristic of power amplifier PTF080551 as desired. After cascading the linearization with power amplifier PTF080551, more than 10dB improvement in IMD3 of the amplifier can be achieved. Furthermore, the linerarizaion is flexible and can be adjusted to linearize different amplifiers.