Advanced Materials Research Vols. 960-961

Abstract: It is known for the traditional milling machine in operation at low speed and efficiency. This paper describes the research of servo motor control strategies for the mobile gantry milling machine. The principles of AC servo motor dynamics, master-slave servo control, and adaptive-neuro fuzzy inference system based on controller are illustrated. Using these strategies when the master servo motor is interference by the external signal, the reference speed of the slave servo motor can follow just like the master motor. Finally the mechanical coupling can be eliminated and the mechanical damage can be avoided.

Abstract: Sub-synchronous oscillation (SSO) caused by highly non-linear HVDC devices can lead to shaft failure and electrical instability of a turbo-generator at oscillation frequency lower than power grid frequency. With increasing HVDC installed in power systems, analysis of SSO becomes a great concern of electrical engineers. In this paper, the reason and process of the SSO are presented by analyzing equations of the mass-springs model. Research methods of SSO are reviewed in HVDC system. And advantages of digital time-domain simulation are demonstrated through combining with algorithm of Prony.

Abstract: Field oriented control (FOC) of permanent magnet synchronous machine (PMSM) is of very importance in electrical vehicle (EV) applications due to low acoustic noise and smooth operation. Nowadays the resolver is most widely used to predict the PMSM rotor position. However, with cost consideration this paper proposes a FOC of PMSM based on Hall effect sensor, , which is very useful in practical applications because of low price and high reliability. Since the Hall effect sensor is an absolute position sensor with 60-degree resolution, the position initialization process is not needed and the reversal rotation risk can be avoided. To improve resolution the interpolation method implemented by software is employed. And the high performance of this proposed method is validated by some experimental results.

Abstract: LLC resonant converter can adjust the output for a wide range of source and load with a small fluctuation of switching frequency, so it is used widely. This paper introduces all arrangements of LLC topological group, then proposes a new topology which is consist of Type-4 and Type-11 that used widely,in this paper we also give its calculate method of resonant frequency. Lastly we get gain characteristics of the topologies in the PSpice simulation environment and analyse the influence factors on adjustment ability in certain load range .

Abstract: Since Ultra High Voltage (UHV) transmission lines have the high charging capacitance, continuous reactive power compensation is vital for efficient operation of long transmission power lines or cables. A continuous reactive compensation will reduce the transmission losses and increase the transmission capacity of active power. In order to achieve the continuous reactive power compensation, we choose the magnetic saturable type reactor. The principle of a magnetic saturable reactor requires a high current ampere-turn coil as its dc bias, and this coil is necessary to use a high temperature superconducting (HTS) winding. As the first stage of the study, we have constructed a 220V small-scale prototype which the dc bias is made of copper coil instead of the HTS coil. The copper coil of the dc bias in small-scale reactor has the same ampere-turn with a 220V HTS controllable reactor (HCR), so its performance keeps the same except the HTS part. Based on this, we made a conceptual design for a 35kV/5Mvar HCR. The output property and harmonic property have been studied by simulation and experiment. The results prove that it can obtain a continuous controllable reactive power output.

Abstract: A flyback switching power supply was designed, which can drive LED stability. The switching power supply is the single-ended flyback structure, and based on PWM driver chip L6561. The input voltage range of the switching power supply is 85V to 265V. The output voltage is 15V and the maximum output current is 2A. The switch power supply is suitable for mobile phone, office equipment and LED. According to experiment, the switching power supply can steadily drive 5 LED, the ripple factor of output is 1.33%, the power efficiency is 85.7%.

Abstract: Based on the CMOS technology, the sawtooth wave oscillator used in switching power supply is designed. In the condition of 27 °C and 4 V power supply voltage, the oscillation frequency of sawtooth wave oscillator is 246.61 KHz. The oscillation frequency of sawtooth wave oscillator changes between 245.94 KHz and 247.89 KHz when the power supply voltage changes between 3V and 6V. The maximum deviation is ±0.52%. From the experimental results, the sawtooth wave oscillator has good linearity, the effect of temperature and power supply to the oscillation frequency of sawtooth wave oscillator is very little. The CMOS sawtooth wave oscillator is suitable for switching power supply.

Abstract: Space vector pulse width modulation (SVPWM) technology can significantly reduce the harmonic content of the inverter output voltage and increase voltage stability compared to other modulation techniques. This paper apply the SVPWM technology in the micro-grid inverter side load voltage stability control, on the basis of dual loop vector inverter control and the basic principles and algorithms of SVPWM. The MATLAB/Simulink simulation show that the response based on SVPWM inverter system changes very rapid load ,the AC side load voltage and frequency control is also very stable.

Abstract: This paper presents a new method which combines the fuzzy theory with the traditional PI control to obtain the accurate tracking of the compensating current of the active power filter (APF) in full frequency range. Online adjustment of the parameters of the controller is realized by using fuzzy reasoning and defuzzication, so as to achieve the accurate tracking of the compensating current and thereby improve the capabilities of the APF to suppress the harmonics effectively. Simulation analysis and experiment results verify the effectiveness of the presented method.

Abstract: A new approach of dual closed-loop control strategy is proposed, and the internal cause of the inverter output voltage waveform distortion is analyzed in this paper. The ability to resist load disturbance is improved by load current feed-forward compensation in the approached scheme. With inner current loop improving the speed of dynamic response, nonlinear load adaptability is enhanced. Pole assignment method is used to design controller parameters, the control scheme is simulated in PSCAD/EMTDC, the nice performance of the proposed control strategy is verified by the simulation results.