scholarly journals A Driving and Control Scheme of High Power Piezoelectric Systems over a Wide Operating Range

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4401
Author(s):  
Tianyue Yang ◽  
Yuanfei Zhu ◽  
Zhiwei Fang ◽  
Haoyu Wu ◽  
Wanlu Jiang ◽  
...  
Keyword(s):  
High Power ◽  
Vibration Amplitude ◽  
Operating Conditions ◽  
Phase Detector ◽  
Displacement Sensor ◽  
Operating Range ◽  
Control Scheme ◽  
Wide Range ◽  
And Control ◽  
Wide Operating

Significant variation in impedance under a wide range of loads increases the difficulty of frequency tracking and vibration control in high-power piezoelectric systems (HPPSs). This paper proposed a wide operating range driving and control scheme for HPPSs. We systematically analyzed the impedance characteristics and deduced the load optimization frequency. In order to provide sufficient drive capability, the inverter combined with an LC matching circuit is configured. With the aid of a transformer ratio arm bridge (TRAB) combined with a proposed pulse-based phase detector (PBPD), the proposed scheme can control the vibration amplitude and keep parallel resonance status under a wide range of loads. Experiments conducted under actual operating conditions verify the feasibility of the proposed scheme under the modal resistance range from 7.40 to 500 Ω and the vibration range from 20% to 100%. Moreover, with the aid of a laser displacement sensor, our scheme is verified to have a vibration amplitude control accuracy better than 2% over a tenfold load variation. This research could be helpful for the driving and control of HPPSs operating in a wide range.

scholarly journals A novel configuration and control of CSI wind energy system with diode rectifier and buck converter

2021 ◽  
Author(s):  
Xiatian Tan
Keyword(s):  
Wind Energy ◽  
High Power ◽  
Reactive Power ◽  
Current Source ◽  
Buck Converter ◽  
Operating Conditions ◽  
Direct Drive ◽  
Control Scheme ◽  
Dc Current ◽  
And Control

This thesis is dedicated to the research of a new converter configuration and control scheme development for direct drive permanent magnet synchronous generator (PMSG) based high power wind energy conversion system (WECS). The proposed converter consists of a diode rectifier, a buck converter and a pulse-width modulated (PWM) current source inverter (CSI). Detailed feasibility study of the proposed configuration is conducted based on the theoretical analysis. A suitable control scheme is designed to optimize the system performance. The maximum power point tracking (MPPT) is achieved through duty cycle adjustment of the buck converter, while the reactive power delivery and the DC current regulation are realized by the CSI controller through manipulating modulation index and delay angle. More importantly, the DC current is evaluated and controlled to the minimum value at various operating conditions. Simulation of a 2 MW WECS is carried out in Matlab/Simulink to verity the control objectives of MPPT, power factor adjustment and DC current minimization. The simulation results prove the feasibility of the proposed system that serves as an attracting alternative for high power WECS.

scholarly journals A novel configuration and control of CSI wind energy system with diode rectifier and buck converter

2021 ◽  
Author(s):  
Xiatian Tan
Keyword(s):  
Wind Energy ◽  
High Power ◽  
Reactive Power ◽  
Current Source ◽  
Buck Converter ◽  
Operating Conditions ◽  
Direct Drive ◽  
Control Scheme ◽  
Dc Current ◽  
And Control

This thesis is dedicated to the research of a new converter configuration and control scheme development for direct drive permanent magnet synchronous generator (PMSG) based high power wind energy conversion system (WECS). The proposed converter consists of a diode rectifier, a buck converter and a pulse-width modulated (PWM) current source inverter (CSI). Detailed feasibility study of the proposed configuration is conducted based on the theoretical analysis. A suitable control scheme is designed to optimize the system performance. The maximum power point tracking (MPPT) is achieved through duty cycle adjustment of the buck converter, while the reactive power delivery and the DC current regulation are realized by the CSI controller through manipulating modulation index and delay angle. More importantly, the DC current is evaluated and controlled to the minimum value at various operating conditions. Simulation of a 2 MW WECS is carried out in Matlab/Simulink to verity the control objectives of MPPT, power factor adjustment and DC current minimization. The simulation results prove the feasibility of the proposed system that serves as an attracting alternative for high power WECS.

Experimental Validation of a Wide-Range Centrifugal Compressor Stage for Supercritical CO2 Power Cycles

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Timothy C. Allison ◽  
Natalie R. Smith ◽  
Robert Pelton ◽  
Jason C. Wilkes ◽  
Sewoong Jung
Keyword(s):  
Centrifugal Compressor ◽  
Operating Conditions ◽  
Successful Implementation ◽  
Compressor Stage ◽  
Test Results ◽  
Power Cycles ◽  
Casing Treatment ◽  
Centrifugal Compressor Stage ◽  
Operating Range ◽  
Wide Range

Successful implementation of sCO2 power cycles requires high compressor efficiency at both the design-point and over a wide operating range in order to maximize cycle power output and maintain stable operation over a wide range of transient and part-load operating conditions. This requirement is particularly true for air-cooled cycles where compressor inlet density is a strong function of inlet temperature that is subject to daily and seasonal variations as well as transient events. In order to meet these requirements, a novel centrifugal compressor stage design was developed that incorporates multiple novel range extension features, including a passive recirculating casing treatment and semi-open impeller design. This design, presented and analyzed for CO2 operation in a previous paper, was fabricated via direct metal laser sintering and tested in an open-loop test rig in order to validate simulation results and the effectiveness of the casing treatment configuration. Predicted performance curves in air and CO2 conditions are compared, resulting in a reduced diffuser width requirement for the air test in order to match design velocities and demonstrate the casing treatment. Test results show that the casing treatment performance generally matched computational fluid dynamics (CFD) predictions, demonstrating an operating range of 69% and efficiency above air predictions across the entire map. The casing treatment configuration demonstrated improvements over the solid wall configuration in stage performance and flow characteristics at low flows, resulting in an effective 14% increase in operating range with a 0.5-point efficiency penalty. The test results are also compared to a traditional fully shrouded impeller with the same flow coefficient and similar head coefficient, showing a 42% range improvement over traditional designs.

scholarly journals Cooling Performance of Arrays of Vibrating Cantilevers

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Mark Kimber ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Vibration Amplitude ◽  
Past Research ◽  
Resonant Mode ◽  
Operating Conditions ◽  
Infrared Thermal Imaging ◽  
Practical Applications ◽  
Wide Range ◽  
Piezoelectric Fans

Piezoelectric fans are vibrating cantilevers actuated by a piezoelectric material and can provide heat transfer enhancement while consuming little power. Past research has focused on feasibility and performance characterization of a single fan, while arrays of such fans, which have important practical applications, have not been widely studied. This paper investigates the heat transfer achieved using arrays of cantilevers vibrating in their first resonant mode. This is accomplished by determining the local convection coefficients due to the two piezoelectric fans mounted near a constant heat flux surface using infrared thermal imaging. The heat transfer performance is quantified over a wide range of operating conditions, including vibration amplitude (7.5–10 mm), distance from heat source (0.01–2 times the fan amplitude), and pitch between fans (0.5–4 times the amplitude). The convection patterns observed are strongly dependent on the fan pitch, with the behavior resembling a single fan for small fan pitch and two isolated fans at a large pitch. The area-averaged thermal performance of the fan array is superior to that of a single fan, and correlations are developed to describe this enhancement in terms of the governing parameters. The best thermal performance is obtained when the fan pitch is 1.5 times its vibration amplitude.

scholarly journals Design of a Wide-Range Centrifugal Compressor Stage for Supercritical CO2 Power Cycles

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Robert Pelton ◽  
Sewoong Jung ◽  
Tim Allison ◽  
Natalie Smith
Keyword(s):  
Operating Conditions ◽  
Low Flow ◽  
Inlet Temperature ◽  
Compressor Stage ◽  
Stage Design ◽  
Power Cycles ◽  
Design Point ◽  
Operating Range ◽  
Wide Range ◽  
Compressor Efficiency

Supercritical carbon dioxide (sCO2) power cycles require high compressor efficiency at both the design point and over a wide operating range. Increasing the compressor efficiency and range helps maximize the power output of the cycle and allows operation over a broader range of transient and part-load operating conditions. For sCO2 cycles operating with compressor inlets near the critical point, large variations in fluid properties are possible with small changes in temperature or pressure. This leads to particular challenges for air-cooled cycles where compressor inlet temperature and associated fluid density are subject to daily and seasonal variations as well as transient events. Design and off-design operating requirements for a wide-range compressor impeller are presented where the impeller is implemented on an integrally geared compressor–expander concept for a high temperature sCO2 recompression cycle. In order to satisfy the range and efficiency requirements of the cycle, a novel compressor stage design incorporating a semi-open impeller concept with a passive recirculating casing treatment is presented that mitigates inducer stall and extends the low flow operating range. The stage design also incorporates splitter blades and a vaneless diffuser to maximize efficiency and operating range. These advanced impeller design features are enabled through the use of direct metal laser sintering (DMLS) manufacturing. The resulting design increases the range from 45% to 73% relative to a conventional closed impeller design while maintaining high design point efficiency.

Active Vibration Damping Using an Inertial, Self-Sensing, Electrodynamic Actuator

2005 ◽  
Author(s):  
Christoph Paulitsch ◽  
Paolo Gardonio ◽  
Stephen J. Elliott
Keyword(s):  
Vibration Amplitude ◽  
Vibration Damping ◽  
Induced Voltage ◽  
Current Feedback ◽  
Control Scheme ◽  
Active Vibration Damping ◽  
Active Vibration ◽  
Voltage Feedback ◽  
And Control ◽  
Inertial Actuator

Self-sensing active vibration damping is advantageous if sensors cannot be placed collocated to actuators or these sensors add too much weight or cost. When self-sensing, electrodynamic actuators are used, damping is directly added to the structure where they are attached without the need of electronic integrators or differentiators that could destabilize the system. Inertial actuators have also the advantage that they do not need to react relative to a fixed ground. In this paper self-sensing control with a shunted resistor, current feedback, induced voltage feedback with and without inductance compensation are investigated in simulations and experiments. Experiments with a lightweight, inertial actuator on a clamped plate show that vibration amplitude is decreased between 6dB and 13dB and control bandwidth is doubled when the appropriate control scheme is used.

Physical Modeling and Control of a Multi-Cylinder HCCI Engine

2009 ◽  
Author(s):  
Nikhil Ravi ◽  
Matthew J. Roelle ◽  
Hsien-Hsin Liao ◽  
Adam F. Jungkunz ◽  
Chen-Fang Chang ◽  
...  
Keyword(s):  
Direct Injection ◽  
Work Output ◽  
Compression Ignition ◽  
Piston Engine ◽  
Modeling And Control ◽  
Hcci Engine ◽  
Operating Region ◽  
Control Scheme ◽  
And Control ◽  
Wide Operating

Homogeneous charge compression ignition (HCCI) is one of the most promising piston-engine concepts for the future, providing significantly improved efficiency and emissions characteristics relative to current technologies. This paper presents a framework for controlling a multi-cylinder HCCI engine with exhaust recompression and direct injection of fuel into the cylinder. A physical model is used to describe the HCCI process, with the model states being closely linked to the thermodynamic state of the cylinder constituents. Separability between the effects of the control inputs on the desired outputs provides an opportunity to develop a simple linear control scheme, where the fuel is used to control the work output and the valve timings are used to control the phasing of combustion. Experimental results show good tracking of both the work output and combustion phasing over a wide operating region. In addition, the controller is able to balance out differences between cylinders, and reduce the cycle-to-cycle variability of combustion.

The performance of a centrifugal compressor with a tandem impeller in off-design conditions

2019 ◽  
Vol 234 (2) ◽  
pp. 156-172 ◽  
Author(s):  
Ziliang Li ◽  
Xingen Lu ◽  
Ge Han ◽  
Yanfeng Zhang ◽  
Shengfeng Zhao ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Performance Enhancement ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Complex Flow ◽  
Maximum Enhancement ◽  
Operating Range ◽  
Wide Range ◽  
Compressor Performance ◽  
Low Efficiency

Centrifugal compressors often suffer relatively low efficiency and a terrible operating range particularly due to the complex flow structure and intense impeller/diffuser interaction. Numerous studies have focused on improving the centrifugal compressor performance using many innovative ideas, such as the tandem impeller, which has become increasingly attractive due to its ability to achieve the flow control with no additional air supply configurations and control costs in compressor. However, few studies that attempted to the investigation of tandem impeller have been published until now and the results are always contradictory. To explore the potential of the tandem impeller to enhance the compressor performance and the underlying mechanism of the flow phenomena in the tandem impellers, this paper numerically investigated a high-pressure-ratio centrifugal compressor with several tandem impellers at off-design operating speeds. The results encouragingly demonstrate that the tandem impeller can achieve a performance enhancement over a wide range of operating conditions. Approximately 1.8% maximum enhancement in isentropic efficiency and 5.0% maximum enhancement in operating range are achieved with the inducer/exducer circumferential displacement of [Formula: see text] = 25% and 50%, respectively. The observed stage performance gain of the tandem impellers decreases when the operating speed increases due to the increased inducer shock, increased wake losses, and deteriorated tandem impeller discharge flow uniformity. In addition, the tandem impeller can extend the impeller operating range particularly at low rotation speeds, which is found to be a result from the suppression of the low-momentum fluid radial movement. The results also indicate that the maximum flux capacity of the tandem impeller decreases due to the restriction of the inducer airfoil Kutta–Joukowsky condition.

Optimal Design of Squeeze Film Supports for Flexible Rotors

1983 ◽  
Vol 105 (3) ◽  
pp. 487-494 ◽  
Author(s):  
M. D. Rabinowitz ◽  
E. J. Hahn
Keyword(s):  
Optimal Design ◽  
Vibration Amplitude ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Rotor Vibration ◽  
Design Constraints ◽  
Supply Pressure ◽  
Flexible Rotors ◽  
Wide Range ◽  
Film Lubrication

Assuming central preloading, operation below the second bending critical speed, and full film lubrication, this paper presents a theoretical model which allows one, with minimum computation, to design squeeze film damped rotors under conditions of high unbalance loading. Closed form expressions are derived for the maximum vibration amplitudes pertaining to optimally damped conditions. The resulting vibration amplitude and transmissibility data of design interest are presented for a wide range of practical operating conditions on a single chart. It can be seen that for a given rotor, the lighter the bearing the more easily one can satisfy design constraints relating to allowable rotor vibration levels and lubricant supply pressure requirements. The data presented are shown to be applicable to a wide variety of rotors, and a recommended procedure for optimal design is outlined.

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