In this paper, it presents a project of a fuzzy controller and a neural estimator to control a coordinate table powered by three-phase induction motor, aiming to implement an intelligent milling system. The position/s...In this paper, it presents a project of a fuzzy controller and a neural estimator to control a coordinate table powered by three-phase induction motor, aiming to implement an intelligent milling system. The position/speed control is performed using vector techniques of three-phase induction machines. The estimation of the motor electromagnetic torque is used for setting the feedrate of the table. The speed control is developed using TS (Takagi-Sugeno) fuzzy logic model and electromagnetic torque estimation using neural network type LMS (least mean square) algorithm. The induction motor is powered by a frequency inverter driven by a DSP (digital signal processor). Control strategies are implemented in DSP. Simulation results are presented for evaluating the performance of the system.展开更多
In this paper, post-fault-tolerant control strategies for quad-inverter multiphase-multilevel induction motor drives are investigated. More specifically, four standard two-level three-phase VSIs (voltage source inver...In this paper, post-fault-tolerant control strategies for quad-inverter multiphase-multilevel induction motor drives are investigated. More specifically, four standard two-level three-phase VSIs (voltage source inverters) supplying the open-end windings of a dual three-phase induction motor is considered, quadrupling the power capability of a single VSI with given voltage and current ratings. In healthy conditions, the control algorithm is able to generate multi-level voltage waveforms, equivalent to the ones of a three-level inverter and to share the total motor power among the four dc sources in each switching period. This sharing capability is investigated under post-fault operating conditions, when one VSI must be completely insulated due to a severe failure on it. In this case, the conversion power unit can operate with a reduced power rating by a proper modulation of the remaining three VSIs. The whole ac motor drive has been numerically implemented, and the effectiveness of the proposed control strategies under healthy and post-fault operating conditions have been proved.展开更多
This paper presents an electronic VSD (variable speed drive) for three-phase IM (induction motor) using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The...This paper presents an electronic VSD (variable speed drive) for three-phase IM (induction motor) using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The drive receives temperature feedback from objects to be cooled and output a corresponding frequency to the IM. A prototype of the VSD is constructed to control a 175 W, four pole, squirrel cage three-phase IM. The heart of the control circuit is a low-cost microchip's PICI6F777 microcontroller which is programmed using C language to generate variable frequency SPWM (sinusoidal pulse width modulation) switching signals. These switching signals are fed to an 1GBT inverter. The VSD constructed can be switched between two modes of speed control" automatic temperature-controlled mode and manual user-controlled mode. Cost savings using the prototype are demonstrated.展开更多
The inter-line dynamic voltage restorer (IDVR) consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for volta...The inter-line dynamic voltage restorer (IDVR) consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder (voltage control mode), the other inverters pump the required power into the dc bus (power control mode). Each inverter will have both voltage and power controllers; only one controller is in use during the abnormal conditions according to its feeder state. The voltage controller uses one of the dynamic voltage restoration techniques. In this paper, the in-phase technique is applied and two types of loads are considered (constant impedance and three phase induction motor). Since the voltage restoration process may need real power injection into the distribution system, the power controller injects this power via voltage injection. This voltage injection is simulated by voltage drop across series virtual impedance. A new scheme is proposed to select the impedance value. The impedance value is selected such that the power consumed by this impedance represents the required power to be transferred without perturbing the load voltage. The performance of this system is also studied during voltage swell. A scheme for operation of multi-feeder IDVR system is proposed in this paper. Simulation results substantiate the proposed concept.展开更多
This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant litera...This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant literature on the efficiency in steam boilers. However, few deal exclusively with feedwater systems. The total horsepower in boiler feed pumps and the corresponding energy consumption estimated for Brazilian industries are as follows: 110.5 MWE of motor driven power and a yearly electricity consumption of 442 GWh for a population of 7,800 steam boilers, approximately. It is estimated that there can be an efficiency improvement in feedwater systems for industrial boilers of 30% on average. To a large extent, these opportunities reside in older boilers that are very common in the Brazilian industrial sector. The most common causes for the low efficiency of feedwater systems are: the control loop of the feedwater, oversized boilers and excessive operational pressure set. Sometimes, the boiler feedwater system can present more than one problem simultaneously. Any kind of solution involves some speed regulation, new pump and number of pumps. Each problem generation facilities were selected in which common inefficiencies cases, the improvement in efficiency can get to 37%. form of intervention in boiler feed pumps, such as: impeller trim, may have more than one solution. Three distinct industrial steam are present. The suggested solutions were analyzed. In these three展开更多
The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors (TSC) as an alternative for voltage regulation during a direct on line three-phase induction motor starting o...The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors (TSC) as an alternative for voltage regulation during a direct on line three-phase induction motor starting on an emulated weak transmission line. Thyristor switched capacitor bank was chosen because it is a well known topology, considering the very nature of the direct starting induction motors, which represents a highly inductive load, the use of switched reactors becomes unnecessary. Such fact minimizes the introduction of harmonics components, and also reduces the cost of the implementation. The binary disposition of the banks allows a variable Var compensation with sixteen steps, in this case. The solution makes use of low cost devices combined with sliding window voltage and current measurement algorithm and a PI control with dead band control for achieve the shown experimental results, where the system is able to manage a typically 20% voltage drop, reducing it to less than 4%. The schematic of the developed circuit, the control technique and a quite simple method to calculate the binary weight capacitors banks are also presented.展开更多
The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constrai...The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constraints. The proposed study has concerned TEFC ( totally Enclosed Fan-Cooled ), 400 V, 50 Hz, SI duty three phase squirrel-cage induction motors only. The motors' designs, with AI and Cu cage, have been optimized in order to reach the minimum efficiency level IE3 at lowest active material costs and satisfy the physical and performance constraints of the designs, which are the motor specifications. A suitable optimization procedure has been used which allowed to find the "best design" by chancing the geometric dimensions of the stator, rotor shape, the stator winding and the stack length. In order to guarantee the goodness and feasibility of the optimized designs, several constrains have been imposed.展开更多
Objective: The aim of the study was to establish an arsenic trioxide (ATO)-resistant cell line of human gallbladder carcinoma, GBC-SD/ATO, and to analyze the differential expressions of its apoptosis-associated gen...Objective: The aim of the study was to establish an arsenic trioxide (ATO)-resistant cell line of human gallbladder carcinoma, GBC-SD/ATO, and to analyze the differential expressions of its apoptosis-associated genes, so as to investigate a correlation between ATO induced resistance of gallbladder carcinoma and expressions of apoptosis associated genes. Methods: The resistant cell line was obtained in vitro by culture of human gallbladder carcinoma cell line GBC-SD with increasingly stepwise concentrations of ATO. The sensitivities of GBC-SD cells and GBC-SD/ATO cells to ATO were determined by MTT assay respectively, cDNA microarray containing 458 apoptosis-related human genes was used to compare the gene expression profiles of GBC-SD/ATO cells and corresponding sensitive cell line GBC-SD. Results: GBC-SD/ATO cell line was established successfully after 8 months of exposure to increasing concentrations of ATO. Compared with the parental cell line, GBC-SD/ATO was 13.6 times more resistant to ATO. Of the 458 apoptosis-related genes, 17 genes were detected having 〉 2-fold difference of expression between the GBC-SD/ATO and GBC-SD cells, with 6 genes up-regulated and 11 genes down-regulated in GBC-SD/ATO cells. Conclusion: The 17 genes invoJved in the apoptosis pathway might be relevant to the resistance of GBC-SD/ATO cells to ATO, suggesting that the modulation of expression of apoptosis-related genes may be a main mechanism of acquired resistance in GBC-SD/ATO.展开更多
The unbalanced voltages cause negative effects on the doubly fed induction generator (DFIG) sucn as torque pulsation,and increased stator current. Based on the symmetrical component theory, the torque pulsation is t...The unbalanced voltages cause negative effects on the doubly fed induction generator (DFIG) sucn as torque pulsation,and increased stator current. Based on the symmetrical component theory, the torque pulsation is the consequence of the interaction of stator and rotor currents of different sequences. This paper presents a control technique to reduce the effect of unbalanced voltages on the DFIG in wind energy conversion systems. The negative sequence stator voltage is derived from the unbalanced three phase stator voltages. The compensated rotor voltage in terms of the derived negative sequence stator voltage and slip which minimizes the negative stator and rotor currents is proposed. The results from the simulation of control system with steady state model and dynamic model of the DFIG show that additional control loop with compensated voltage can significantly reduce torque and reactive power pulsations.展开更多
文摘In this paper, it presents a project of a fuzzy controller and a neural estimator to control a coordinate table powered by three-phase induction motor, aiming to implement an intelligent milling system. The position/speed control is performed using vector techniques of three-phase induction machines. The estimation of the motor electromagnetic torque is used for setting the feedrate of the table. The speed control is developed using TS (Takagi-Sugeno) fuzzy logic model and electromagnetic torque estimation using neural network type LMS (least mean square) algorithm. The induction motor is powered by a frequency inverter driven by a DSP (digital signal processor). Control strategies are implemented in DSP. Simulation results are presented for evaluating the performance of the system.
文摘In this paper, post-fault-tolerant control strategies for quad-inverter multiphase-multilevel induction motor drives are investigated. More specifically, four standard two-level three-phase VSIs (voltage source inverters) supplying the open-end windings of a dual three-phase induction motor is considered, quadrupling the power capability of a single VSI with given voltage and current ratings. In healthy conditions, the control algorithm is able to generate multi-level voltage waveforms, equivalent to the ones of a three-level inverter and to share the total motor power among the four dc sources in each switching period. This sharing capability is investigated under post-fault operating conditions, when one VSI must be completely insulated due to a severe failure on it. In this case, the conversion power unit can operate with a reduced power rating by a proper modulation of the remaining three VSIs. The whole ac motor drive has been numerically implemented, and the effectiveness of the proposed control strategies under healthy and post-fault operating conditions have been proved.
文摘This paper presents an electronic VSD (variable speed drive) for three-phase IM (induction motor) using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The drive receives temperature feedback from objects to be cooled and output a corresponding frequency to the IM. A prototype of the VSD is constructed to control a 175 W, four pole, squirrel cage three-phase IM. The heart of the control circuit is a low-cost microchip's PICI6F777 microcontroller which is programmed using C language to generate variable frequency SPWM (sinusoidal pulse width modulation) switching signals. These switching signals are fed to an 1GBT inverter. The VSD constructed can be switched between two modes of speed control" automatic temperature-controlled mode and manual user-controlled mode. Cost savings using the prototype are demonstrated.
文摘The inter-line dynamic voltage restorer (IDVR) consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder (voltage control mode), the other inverters pump the required power into the dc bus (power control mode). Each inverter will have both voltage and power controllers; only one controller is in use during the abnormal conditions according to its feeder state. The voltage controller uses one of the dynamic voltage restoration techniques. In this paper, the in-phase technique is applied and two types of loads are considered (constant impedance and three phase induction motor). Since the voltage restoration process may need real power injection into the distribution system, the power controller injects this power via voltage injection. This voltage injection is simulated by voltage drop across series virtual impedance. A new scheme is proposed to select the impedance value. The impedance value is selected such that the power consumed by this impedance represents the required power to be transferred without perturbing the load voltage. The performance of this system is also studied during voltage swell. A scheme for operation of multi-feeder IDVR system is proposed in this paper. Simulation results substantiate the proposed concept.
文摘This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant literature on the efficiency in steam boilers. However, few deal exclusively with feedwater systems. The total horsepower in boiler feed pumps and the corresponding energy consumption estimated for Brazilian industries are as follows: 110.5 MWE of motor driven power and a yearly electricity consumption of 442 GWh for a population of 7,800 steam boilers, approximately. It is estimated that there can be an efficiency improvement in feedwater systems for industrial boilers of 30% on average. To a large extent, these opportunities reside in older boilers that are very common in the Brazilian industrial sector. The most common causes for the low efficiency of feedwater systems are: the control loop of the feedwater, oversized boilers and excessive operational pressure set. Sometimes, the boiler feedwater system can present more than one problem simultaneously. Any kind of solution involves some speed regulation, new pump and number of pumps. Each problem generation facilities were selected in which common inefficiencies cases, the improvement in efficiency can get to 37%. form of intervention in boiler feed pumps, such as: impeller trim, may have more than one solution. Three distinct industrial steam are present. The suggested solutions were analyzed. In these three
文摘The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors (TSC) as an alternative for voltage regulation during a direct on line three-phase induction motor starting on an emulated weak transmission line. Thyristor switched capacitor bank was chosen because it is a well known topology, considering the very nature of the direct starting induction motors, which represents a highly inductive load, the use of switched reactors becomes unnecessary. Such fact minimizes the introduction of harmonics components, and also reduces the cost of the implementation. The binary disposition of the banks allows a variable Var compensation with sixteen steps, in this case. The solution makes use of low cost devices combined with sliding window voltage and current measurement algorithm and a PI control with dead band control for achieve the shown experimental results, where the system is able to manage a typically 20% voltage drop, reducing it to less than 4%. The schematic of the developed circuit, the control technique and a quite simple method to calculate the binary weight capacitors banks are also presented.
文摘The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constraints. The proposed study has concerned TEFC ( totally Enclosed Fan-Cooled ), 400 V, 50 Hz, SI duty three phase squirrel-cage induction motors only. The motors' designs, with AI and Cu cage, have been optimized in order to reach the minimum efficiency level IE3 at lowest active material costs and satisfy the physical and performance constraints of the designs, which are the motor specifications. A suitable optimization procedure has been used which allowed to find the "best design" by chancing the geometric dimensions of the stator, rotor shape, the stator winding and the stack length. In order to guarantee the goodness and feasibility of the optimized designs, several constrains have been imposed.
基金Supported by the grants from the Research Fund of the Educational Department of Zhejiang Province (No 20070609)Natural Science Foundation of Zhejiang Province (No Y206860)Natural Science Foundation of Zhejiang Province (No Y207802)
文摘Objective: The aim of the study was to establish an arsenic trioxide (ATO)-resistant cell line of human gallbladder carcinoma, GBC-SD/ATO, and to analyze the differential expressions of its apoptosis-associated genes, so as to investigate a correlation between ATO induced resistance of gallbladder carcinoma and expressions of apoptosis associated genes. Methods: The resistant cell line was obtained in vitro by culture of human gallbladder carcinoma cell line GBC-SD with increasingly stepwise concentrations of ATO. The sensitivities of GBC-SD cells and GBC-SD/ATO cells to ATO were determined by MTT assay respectively, cDNA microarray containing 458 apoptosis-related human genes was used to compare the gene expression profiles of GBC-SD/ATO cells and corresponding sensitive cell line GBC-SD. Results: GBC-SD/ATO cell line was established successfully after 8 months of exposure to increasing concentrations of ATO. Compared with the parental cell line, GBC-SD/ATO was 13.6 times more resistant to ATO. Of the 458 apoptosis-related genes, 17 genes were detected having 〉 2-fold difference of expression between the GBC-SD/ATO and GBC-SD cells, with 6 genes up-regulated and 11 genes down-regulated in GBC-SD/ATO cells. Conclusion: The 17 genes invoJved in the apoptosis pathway might be relevant to the resistance of GBC-SD/ATO cells to ATO, suggesting that the modulation of expression of apoptosis-related genes may be a main mechanism of acquired resistance in GBC-SD/ATO.
文摘The unbalanced voltages cause negative effects on the doubly fed induction generator (DFIG) sucn as torque pulsation,and increased stator current. Based on the symmetrical component theory, the torque pulsation is the consequence of the interaction of stator and rotor currents of different sequences. This paper presents a control technique to reduce the effect of unbalanced voltages on the DFIG in wind energy conversion systems. The negative sequence stator voltage is derived from the unbalanced three phase stator voltages. The compensated rotor voltage in terms of the derived negative sequence stator voltage and slip which minimizes the negative stator and rotor currents is proposed. The results from the simulation of control system with steady state model and dynamic model of the DFIG show that additional control loop with compensated voltage can significantly reduce torque and reactive power pulsations.