Active Vibration Control of the Flexible Rotor in High Energy Density Magnetically Suspended Motor With Mode Separation Method

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Enqiong Tang ◽  
Jiancheng Fang ◽  
Bangcheng Han
Keyword(s):  
Energy Density ◽  
Critical Speed ◽  
Active Vibration Control ◽  
High Energy ◽  
Separation Method ◽  
High Energy Density ◽  
Flexible Rotor ◽  
Mode Separation ◽  
Displacement Signal ◽  
Bending Mode

Since the mass of the rotor in high energy density magnetically suspended motor (HEDMSM) is always large and there are only three balancing planes on the flexible rotor restricted by the structure of the motor, which means that the second bending mode cannot be balanced using N + 1 planes method which is always applied to balance the flexible rotor. Then, the rotor displacements maybe large and this situation will make the system consume large amplifier currents when the rotor passes the first bending critical speed. Therefore, the mode separation method is proposed to separate the first and the second bending modes in rotor displacement and reconstruct the displacement signal nearby the first bending mode. Then, the original rotor displacement signal used by the digital controller is substituted by the reconstructed displacement signal and the amplifier current is reduced a lot when the rotor passes the first bending critical speed. Finally, the experiment of mode separation is carried out in 100 kW magnetically suspended motor and the experiment results show the effectiveness and superiority of the mode separation method in reducing the amplifier current when the rotor passes the first bending critical speed.

Active Vibration Control of the Flexible Rotor to Pass the First Bending Critical Speed in High Energy Density Magnetically Suspended Motor

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Enqiong Tang ◽  
Jiancheng Fang ◽  
Shiqiang Zheng ◽  
Dikai Jiang
Keyword(s):  
Critical Speed ◽  
Active Vibration Control ◽  
High Energy ◽  
High Energy Density ◽  
Flexible Rotor ◽  
Linear Quadratic ◽  
Variance Matrix ◽  
Active Vibration ◽  
Integral Controller ◽  
Optimal State Feedback

In order to minimizing the rotor displacement and the amplifier current mainly caused by the unbalance forces when the flexible rotor passes the first bending critical speed, the optimal controller is presented in this paper. The accurate modeling method for the flexible rotor based on the sine sweeping measurements is investigated. The design of the Kalman estimator and the choice of the variance matrix elements have been described. The optimal state feedback regulator with an integral controller has been used for stabilizing the system and the determination of the weight matrices has been investigated in detail. The influences of the specific elements of the weight matrices on the resonance peak of the flexible rotor when passing the first bending critical speed are analyzed. Finally, the running up test of the flexible rotor is implemented and the result shows the effectiveness of linear quadratic Gaussian (LQG) controller minimizing the rotor displacement and the amplifier current nearby the first bending critical speed. Furthermore, the comparison between the proportional-integral-differential (PID) controller with phase lead compensator and the LQG controller verifies the superiority of LQG controller in reducing the amplifier currents.

Optimum Damping Control of the Flexible Rotor in High Energy Density Magnetically Suspended Motor

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Jiancheng Fang ◽  
Enqiong Tang ◽  
Shiqiang Zheng
Keyword(s):  
Control System ◽  
Energy Density ◽  
Critical Speed ◽  
Control Method ◽  
High Energy ◽  
Magnetic Bearing ◽  
High Energy Density ◽  
Damping Control ◽  
Bearing Force ◽  
Voltage Saturation

The rated rotational speed of the magnetically suspended motor (MSM) is always above the bending critical speed to achieve high energy density. The rotor will have a dramatic resonance when it passes the critical speed. Then, the magnetic bearing has to provide large bearing force to suppress the synchronous vibration. However, the bearing force is always limited by magnetic saturation and power amplifier voltage saturation. This paper proposed an optimum damping control method which can make effective use of the limited bearing force to minimize the synchronous vibration amplitude of the rotor nearby the critical speed. The accurate rotor model is obtained by theoretical analysis and system identification. The unbalance force response of the bending mode of the rotor is analyzed. The small gain theorem is used to determine the range of the magnitude of the control system. Then, the relationship of the optimum damping varying with the magnitude and phase of the control system nearby the critical speed is analyzed. The run-up experiments are carried out in 315 kW MSM and the results show the effectiveness and superiority of the optimum damping control method.

A HIGH ENERGY DENSITY ZINC/OXYGEN BATTERY SYSTEM

1966 ◽  
Author(s):  
S. CHODOSH ◽  
E. KATSOULIS ◽  
M. ROSANSKY
Keyword(s):  
Energy Density ◽  
High Energy ◽  
High Energy Density ◽  
Battery System

Efficient Co-Harvesting of Solar Energy and Low-Grade Heat by Molecular Photoswitches for High Energy Density, Long-Term Stable Solar Thermal Battery

2019 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Tao LI
Keyword(s):  
Energy Density ◽  
Solar Energy ◽  
High Performance ◽  
High Energy ◽  
Solar Thermal ◽  
High Energy Density ◽  
Low Grade ◽  
Thermal Battery ◽  
Low Grade Heat

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.

Efficient Co-Harvesting of Solar Energy and Low-Grade Heat by Molecular Photoswitches for High Energy Density, Long-Term Stable Solar Thermal Battery

2019 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Tao LI
Keyword(s):  
Energy Density ◽  
Solar Energy ◽  
High Performance ◽  
High Energy ◽  
Solar Thermal ◽  
High Energy Density ◽  
Low Grade ◽  
Thermal Battery ◽  
Low Grade Heat

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.

Si Nanowire Anode Prepared by Chemical Etching for High Energy Density Lithium-ion Battery

2013 ◽  
Vol 28 (11) ◽  
pp. 1207-1212 ◽  
Author(s):  
Jian-Wen LI ◽  
Ai-Jun ZHOU ◽  
Xing-Quan LIU ◽  
Jing-Ze LI
Keyword(s):  
Energy Density ◽  
Lithium Ion Battery ◽  
Chemical Etching ◽  
Lithium Ion ◽  
High Energy ◽  
High Energy Density ◽  
Si Nanowire

Stabilization of Nickel-Rich Layered Cathode Materials of High Energy Density by Ca Doping

2018 ◽  
Vol 28 (5) ◽  
pp. 273-278
Author(s):  
Beomhee Kang ◽  
Soonhyun Hong ◽  
Hongkwan Yoon ◽  
Dojin Kim ◽  
Chunjoong Kim
Keyword(s):  
Energy Density ◽  
Cathode Materials ◽  
High Energy ◽  
High Energy Density ◽  
Ca Doping ◽  
Layered Cathode Materials

Synthesis of New High Energy Density Matter (HEDM): Extra High Energy Oxidizers and Fuels

2000 ◽  
Author(s):  
Robert J. Schmitt ◽  
Jeffrey C. Bottaro ◽  
Mark Petrie ◽  
Paul E. Penwell
Keyword(s):  
Energy Density ◽  
High Energy ◽  
High Energy Density ◽  
Density Matter
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