This paper proposes a high performance double-interleaved dual boost （DIDB） technique to solve the problems of high ripple current, large inductor size and the requirement of step-up transformer in many case found i...This paper proposes a high performance double-interleaved dual boost （DIDB） technique to solve the problems of high ripple current, large inductor size and the requirement of step-up transformer in many case found in the conventional DC-DC boost converter. The 3-phase grid connected converter with decoupling control give an independent control between active and reactive power using the load current feed-forward. With this technique, the disturbance rejection and the output power quality can be improved. Experiments are conducted with three case studies： 1） a test of the DIDB converter to determine current ripple and voltage gain, 2） a test of the 3-phase grid connected converter to determine DC-link voltage regulation, power factor and total harmonic distortion （THD）, and 3） a test of the overall system with a 7.5 kW wind turbine simulator by step and various input wind speeds to determine the output power at the grid side and verify the maximum peak power tracking （MPPT） performance. The results can confirm that the DIDB converter gives lower ripple current and higher voltage gain than the conventional converter. For the grid side, the 3-phase grid connected converter can regulate the DC-link with fast dynamic response to disturbance rejection and low overshoot while complying with the THD standard defined in IEEE 519-1992. In addition, the MPPT controller is able to achieve the maximum energy capture with the various input wind speeds.展开更多
This paper presents an electric drive system whose motor is connected to a battery by means of a buck DC/DC converter. This motor is further connected to an ultracapacitor by means of a boost DC/DC converter. First, o...This paper presents an electric drive system whose motor is connected to a battery by means of a buck DC/DC converter. This motor is further connected to an ultracapacitor by means of a boost DC/DC converter. First, operation and break processes are studied when the converters are switched off as well as when they are switched on in current limitation mode. Then, a comparative analysis of the results in the two operation modes is done.展开更多
This paper presents a novel remote controlled dexterous robot arm with 6 degrees of freedom （DOF）. As a highly integrated mechatronics system, sensors and their signal processing system are integrated inside each jo...This paper presents a novel remote controlled dexterous robot arm with 6 degrees of freedom （DOF）. As a highly integrated mechatronics system, sensors and their signal processing system are integrated inside each joint. To lighten the weight, almost all mechanical parts are made of aluminum and the robot control system is placed outside. The modular concept is adopted during the robot design process for time and cost saving. Considering the much greater torque acted on the two shoulder joints, the joint shells are strengthened in the design to increase joint stiffness and suppress system vibration. Meanwhile, to simplify the maintenance, a new spring pins electronic connector is designed to disassemble every joint, connector and link independently without cutting any cables. The teleoperation technology enables the robot to offer more convenient service definitely for people＇ s daily life. Virtual reality technology is used to solve the time delay problem during teleoperation. Finally, two typical daily chore experiments are implemented to prove the manipulation ability of the dexterous robot arm.展开更多
The quantity of installed PV （photovoltaic） systems in the German distribution grid is still increasing. In some areas, the installed PV capacity exceeds 5 kW per HC （house connection）. Therefore, the load flow ch...The quantity of installed PV （photovoltaic） systems in the German distribution grid is still increasing. In some areas, the installed PV capacity exceeds 5 kW per HC （house connection）. Therefore, the load flow changes its characteristics and leads to new requirements for the grid. In some areas, the power feedback is higher than the delivery and the installed PV capacity becomes the decisive factor for grid planning. This paper discusses the impact of PV systems on the flicker level. The focus hereby is on the correlation among the flicker level, the grid voltage and the meteorological parameters. Different approaches to investigate if there is an influence of PV systems on the maximum flicker are taken into account. Furthermore, an investigation if the normative limit is exceeded will be shown.展开更多
In this research, convective and microwave drying characteristics, energy requirement and color changes of dill leaves （Anethum graveolens L.） were reported. Dill leaves were dehydrated in a computer connected paral...In this research, convective and microwave drying characteristics, energy requirement and color changes of dill leaves （Anethum graveolens L.） were reported. Dill leaves were dehydrated in a computer connected parallel air flow type dryer and in a microwave oven dryer. Samples of freshly harvested dill leaves were dehydrated under three air temperatures of 50, 60 and 70 ℃, and at three microwave power levels of PL-1 （90 W）, PL-2 （160 W） and PL-3 （350 W）. Selected drying air velocity was 0.30 m/s for all temperatures. Dill leaves were dehydrated from the initial moisture content of 735 （percentage dry basis） to a final moisture content of 8%-10%. During convective drying experiment, products were weighted automatically by the balance per 5-10 min. Data were transferred to the computer and processed by software. During microwave drying, the products were weighted, and data were recorded manually per 15-60 min. The influence of drying method, drying air temperature and microwave power level has also been studied. Hunter L, a, b values system was also used to evaluate changes in total color difference （AE） on dried products. The results showed that convective drying air temperature and microwave oven power levels influenced the total drying time, total energy requirement, specific energy requirement and color difference for dill leaves. The minimum specific energy requirement was determined as 10.72 kWh/kg and 18.72 kWh/kg for 70 ℃ and PL-3, respectively. 70℃ drying air temperature and PL-3 were found to yield better quality product in terms of color retention of Hunter L, a, b and AE. As a result, to reduce drying energy consumption and to keep better color retention, convective drying can be recommended for this application.展开更多
A distribution grid is generally characterized by a high R/X （resistance/reactance） ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in su...A distribution grid is generally characterized by a high R/X （resistance/reactance） ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in such a way that power flows from transmission system via distribution system to consumers. But in a situation when wind turbines are connected to the distribution grid, the power source will change from one source to two sources, in this case, network is said to be active. This may probably have an impact on the distribution grid to whenever the wind turbine is connected. The best way to know the impact of wind turbine on the distribution grid in question is by carrying out load flow analysis on that system with and without the connection of wind turbines. Two major fundamental calculations： the steady-state voltage variation at the PCC （point of common coupling） and the calculation of short-circuit power of the grid system at the POC （point of connection） are necessary before carrying out the load flow study on the distribution grid. This paper, therefore, considers these pre-load flow calculations that are necessary before carrying out load flow study on the test distribution grid. These calculations are carded out on a test distribution system.展开更多
文摘This paper proposes a high performance double-interleaved dual boost （DIDB） technique to solve the problems of high ripple current, large inductor size and the requirement of step-up transformer in many case found in the conventional DC-DC boost converter. The 3-phase grid connected converter with decoupling control give an independent control between active and reactive power using the load current feed-forward. With this technique, the disturbance rejection and the output power quality can be improved. Experiments are conducted with three case studies： 1） a test of the DIDB converter to determine current ripple and voltage gain, 2） a test of the 3-phase grid connected converter to determine DC-link voltage regulation, power factor and total harmonic distortion （THD）, and 3） a test of the overall system with a 7.5 kW wind turbine simulator by step and various input wind speeds to determine the output power at the grid side and verify the maximum peak power tracking （MPPT） performance. The results can confirm that the DIDB converter gives lower ripple current and higher voltage gain than the conventional converter. For the grid side, the 3-phase grid connected converter can regulate the DC-link with fast dynamic response to disturbance rejection and low overshoot while complying with the THD standard defined in IEEE 519-1992. In addition, the MPPT controller is able to achieve the maximum energy capture with the various input wind speeds.
文摘This paper presents an electric drive system whose motor is connected to a battery by means of a buck DC/DC converter. This motor is further connected to an ultracapacitor by means of a boost DC/DC converter. First, operation and break processes are studied when the converters are switched off as well as when they are switched on in current limitation mode. Then, a comparative analysis of the results in the two operation modes is done.
文摘This paper presents a novel remote controlled dexterous robot arm with 6 degrees of freedom （DOF）. As a highly integrated mechatronics system, sensors and their signal processing system are integrated inside each joint. To lighten the weight, almost all mechanical parts are made of aluminum and the robot control system is placed outside. The modular concept is adopted during the robot design process for time and cost saving. Considering the much greater torque acted on the two shoulder joints, the joint shells are strengthened in the design to increase joint stiffness and suppress system vibration. Meanwhile, to simplify the maintenance, a new spring pins electronic connector is designed to disassemble every joint, connector and link independently without cutting any cables. The teleoperation technology enables the robot to offer more convenient service definitely for people＇ s daily life. Virtual reality technology is used to solve the time delay problem during teleoperation. Finally, two typical daily chore experiments are implemented to prove the manipulation ability of the dexterous robot arm.
文摘The quantity of installed PV （photovoltaic） systems in the German distribution grid is still increasing. In some areas, the installed PV capacity exceeds 5 kW per HC （house connection）. Therefore, the load flow changes its characteristics and leads to new requirements for the grid. In some areas, the power feedback is higher than the delivery and the installed PV capacity becomes the decisive factor for grid planning. This paper discusses the impact of PV systems on the flicker level. The focus hereby is on the correlation among the flicker level, the grid voltage and the meteorological parameters. Different approaches to investigate if there is an influence of PV systems on the maximum flicker are taken into account. Furthermore, an investigation if the normative limit is exceeded will be shown.
文摘In this research, convective and microwave drying characteristics, energy requirement and color changes of dill leaves （Anethum graveolens L.） were reported. Dill leaves were dehydrated in a computer connected parallel air flow type dryer and in a microwave oven dryer. Samples of freshly harvested dill leaves were dehydrated under three air temperatures of 50, 60 and 70 ℃, and at three microwave power levels of PL-1 （90 W）, PL-2 （160 W） and PL-3 （350 W）. Selected drying air velocity was 0.30 m/s for all temperatures. Dill leaves were dehydrated from the initial moisture content of 735 （percentage dry basis） to a final moisture content of 8%-10%. During convective drying experiment, products were weighted automatically by the balance per 5-10 min. Data were transferred to the computer and processed by software. During microwave drying, the products were weighted, and data were recorded manually per 15-60 min. The influence of drying method, drying air temperature and microwave power level has also been studied. Hunter L, a, b values system was also used to evaluate changes in total color difference （AE） on dried products. The results showed that convective drying air temperature and microwave oven power levels influenced the total drying time, total energy requirement, specific energy requirement and color difference for dill leaves. The minimum specific energy requirement was determined as 10.72 kWh/kg and 18.72 kWh/kg for 70 ℃ and PL-3, respectively. 70℃ drying air temperature and PL-3 were found to yield better quality product in terms of color retention of Hunter L, a, b and AE. As a result, to reduce drying energy consumption and to keep better color retention, convective drying can be recommended for this application.
文摘A distribution grid is generally characterized by a high R/X （resistance/reactance） ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in such a way that power flows from transmission system via distribution system to consumers. But in a situation when wind turbines are connected to the distribution grid, the power source will change from one source to two sources, in this case, network is said to be active. This may probably have an impact on the distribution grid to whenever the wind turbine is connected. The best way to know the impact of wind turbine on the distribution grid in question is by carrying out load flow analysis on that system with and without the connection of wind turbines. Two major fundamental calculations： the steady-state voltage variation at the PCC （point of common coupling） and the calculation of short-circuit power of the grid system at the POC （point of connection） are necessary before carrying out the load flow study on the distribution grid. This paper, therefore, considers these pre-load flow calculations that are necessary before carrying out load flow study on the test distribution grid. These calculations are carded out on a test distribution system.
