Design of Automatic Quasi-synchronizing Device in Rural Small Hydropower Station

Generator synchronization is an important and frequent operation in rural small hydropower station. In order to ensure that generator can be paralleled in the grid automatically, efficiently, and stably in the rural small hydropower station whose parallel in operation still needs to be accomplished manually. This paper described an automatic quasi-synchronizing device, based on 89C52 Single-chip Microcomputer （SCM）. Its hardware includes three modules and its software is structuralized. The device structure is simple, and its reliability is high and the maintenance is easy. Besides, convenient Human Machine Interface （HMI） makes the parameter setting simple and flexible

A PLL Clock Frequency Multiplier Using Dynamic Current Matching Adaptive Charge-Pump and VCO Frequency Reuse

A 3.5 times PLL clock frequency multiplier for low voltage different signal （LVDS） driver is presented. A novel adaptive charge pump can automatically switch the loop bandwidth and a voltage-controlled oscillator （VCO） is designed with the aid of frequency ranges reuse technology. The circuit is implemented using 1st Silicon 0.25 μm mixed-signal complementary metal-oxide-semiconductor （CMOS） process. Simulation results show that the PLL clock frequency multiplier has very low phase noise and very short capture time .

Design and analysis of a three-stage voltage-controlled ring oscillator

This paper describes a large tuning range low phase noise voltage-controlled ring oscillator （ring VCO） based on a different cascade voltage logic delay cell with current-source load to change the current of output node. The method for optimization is presented. Furthermore, the analysis of performance of the proposed ring VCO is confirmed by the measurement results. The three-stage proposed ring VCO was fabricated in the 180-nm CMOS process of SMIC. The measurement results show that the oscillator frequency of the ring VCO is from 0.77O to 5.286 GHz and the phase noise is 97.93 dBc/Hz at an offset of 1 MHz from 5.268 GHz with a total power of 15.1 mW from a 1.8 V supply while occupying only 0.00175 mm2 of the core die area.

A robust solution for hesitate phenomenon in pick up process of aerospace electromagnetic relay

As for aerospace electromagnetic relay （AEMR） which is of small batches and having difficulty in automatic production, the uncertainty phenomenon is remarkable due to excessive manual work involved in the assembly and adjustment processes. This kind of uncertainty may increase the coil voltage difference （CVD） caused by hesitate phenomenon in the pick up process of AEMR. Taking a certain type of AEMR for example, the CVD problem in the actual producing process has been studied in this paper. The primary cause of this issue, two-steps of armature motion （namely hesitate phenomenon） in the pick up process, has been found by analyzing the matching characteristics of electromagnetic and mechanical torques of AEMR. Through the optimization of the matching characteristics, the two-steps of armature motion problem is solved by robust design of the return reed which is a key part of AEMR. The validity of this research has been proved by the comparison of characteristics of AMER before and after the optimization.