Topic
Variable-frequency drive
About: Variable-frequency drive is a research topic. Over the lifetime, 837 publications have been published within this topic receiving 5691 citations. The topic is also known as: VFD.
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15 Jun 2015
TL;DR: In this article, a relay feedback based online parameter identification method was proposed to enable coordinated operation of double closed loop, and there was no impact to normal operation of system during the identification, so PID tuning parameter can be updated online and real time.
Abstract: Electromagnetic speed regulation coal cutter has simple structure and high performance cost ratio, and the PID or improved PID controller can enable stable and high efficiency operation of coal cutter. Since the underground coal mine has complex and uncertain operation condition, the coal cutter during actual operation may not reach the predicted performance requirement, controller parameter shall be adjusted. Electromagnetic speed regulation coal cutter system parameter identification method, on the basis of relay feedback self-tuning, is proposed, and relay cascade feedback control is introduced to respectively online optimize control parameter of speed loop and current loop, update controller parameter, and evaluate system response performance. The simulation and test result verifies the effectiveness of parameter identification result of the method, and improves the anti-jamming capability of the control system. Introduction The coal cutter is the critical electric equipment for coal mine production. At present, the domestic coal cutter almost all adopts electric traction mode. According to the traction motor type, it can be divided into variable frequency drive, switch reluctance drive and electromagnetic speed regulation types, wherein, electromagnetic speed regulation coal cutter has stable operation, low cost and easy maintenance with certain position among coal cutter driving. Electromagnetic speed regulation motor is also called slop frequency motor, the slip frequency clutch regulates the excitation current to change magnetic flux and realize energy exchange and AC speed control. The control mode is usually PID closed loop control to regulate rotation speed output of motor. Literature 1 analyzed the operation principle of double closed loop of electromagnetic speed regulation motor, and manual experience modification method was adopted to regulate system PID parameter with fairly low efficiency; Literature 2 adopted mathematical model structure of current loop and speed loop in case of double closed loop control, but there was no analysis and simulation for the system parameter; Literature 3 studied the operation condition characteristic of electromagnetic speed regulation coal cutter brake operation, and analyzed the impact of coal cutter system parameter to brake performance, but there was no quantitative analysis by using theoretical method; Literature 4 pointed out the problems of simulation PID regulator parameter drifting and commissioning of electromagnetic speed regulation motor, and adopted maximum membership degree ambiguity resolution controller real time regulation and simulation curve to present that, fuzzy controller control was more unblocked, but compilation of fuzzy rule also relied on manual offline resolution 3rd International Conference on Management, Education, Information and Control (MEICI 2015) © 2015. The authors Published by Atlantis Press 363 and could not realize self-adaptation online identification. Aiming at complicated operation condition characteristics of electromagnetic speed regulation coal cutter, this paper proposes the relay feedback based online parameter identification method, adopts the cascade feedback to enable coordinated operation of double closed loop, and there is no impact to normal operation of system during the parameter identification, so PID tuning parameter can be updated online and real time. Parameter Tuning Method of Control System of Electromagnetic Speed Regulation Coal Cutter Structure Characteristic and Control Mode. The electromagnetic speed regulation motor is composed of two parts as drive and driven, as shown in Fig. 1.
2 citations
Patent•
20 Jul 2014
TL;DR: In this paper, the authors describe a pump set consisting of a centrifugal pump and a submersible electric motor placed in the flow string and suspended at the sting of buried pipes.
Abstract: FIELD: oil and gas industry.SUBSTANCE: method lies in periodical repetition of cycles consisting of pumping, frequency search, stopping delivery and accumulation. At that in order to ensure pumping of fluid from the well equal to its influx the pump set is selected with a higher pump capacity in comparison with fluid influx from formation to the well. In process of cycles performance correction is made for pumping-accumulation time ratio depending on results of operation in the previous cycles until pumping-accumulation time ratio stops varying. The moment of stopping delivery is defined by equation of values of current torque at the shaft of a submerged electric motor and reference torque, which is determined preliminary against sudden drop of torque at the motor shaft at the point of stopping delivery at reduction of feed voltage frequency. The device contains a pump set consisting of a centrifugal pump and a submersible electric motor placed in the flow string and suspended at the sting of buried pipes. At that the submersible motor by its conducting cable is coupled to the frequency converter and control unit placed over the ground. Also the device contains a matching transformer, an evaluator of frequency, current, torque and power, a coupling unit, indication and control unit. At that the conducting cable is coupled to the first input-output of the matching transformer, which is coupled by its second input-output to the input-output of the frequency converter. The frequency converter by its second input-output is coupled to the power supply unit and by its third input-output to the first input-output of the evaluator of frequency, current, torque and power, which is by its second is coupled to the first input-output of the coupling unit, which second input-output is coupled to the fourth input-output of the frequency converter and the third input-output is coupled to the first input-output of the master controller, which second input-output is coupled to the indication and control unit. At that the device arranges receipt of all signals to the units placed above ground through the conducting cable directly from the shaft of the submersible electric motor.EFFECT: improvement of the method efficiency and operational reliability of the device both in low- and high-yield wells.2 cl, 3 dwg
2 citations
01 Dec 2015
TL;DR: In this article, the authors proposed a power electronic circuit which can be incorporated with some change in the existing wiring circuit of the refrigerator for variable speed operation of the motor, which can reduce the inrush current during starting.
Abstract: Variable frequency drive of single-phase induction motor can have many potential advantages, like reduced inrush current during starting, high starting torque, possibility of higher efficiency, more tolerant to variation in grid supply voltage etc Many of the existing electrical gadgets use single-phase induction motor of capacitor start / capacitor-run type A typical example is the motor used in household refrigerators In this application the starting torque requirement is high It will be good if the motor starts with reduced inrush current and if the amount of cooling by refrigerator is controlled by variable speed operation of the motor This work proposes a power electronic circuit which can be incorporated with some change in the existing wiring circuit of the refrigerator
2 citations
Patent•
10 Jul 2014
TL;DR: In this article, a variable frequency drive system for controlling a pump driven by a variable-frequency electric motor with the pump in fluid communication with a fluid system is described, where the maximum flow required for the particular flow system in which the pump is operating and adding an initial pump starting module that limits the initial starting flow rate from the pump to the desired maximum flow rate for the system is separately calculated.
Abstract: This invention provides, in various embodiments, a variable frequency drive system for controlling a pump driven by a variable frequency electric motor, with the pump in fluid communication with a fluid system. The drive system of this invention improves the efficiency of the prior variable frequency drive systems by inserting into the memory of the variable frequency drive the maximum flow required for the particular flow system in which the pump is operating and adding an initial pump starting module that limits the initial starting flow rate from the pump to the desired maximum flow rate for the system, which is separately calculated.
2 citations
TL;DR: In this article, variable frequency drive (VFD) is installed which adjusted air flow as needed so that energy waste can be reduced and the result shows that by using VFD, 8,233,573.444 KWh (8.45 GWh) can be saved a year.
Abstract: A reporting of Energy Audit in 2018 by LEMTEK UI has reported that air fan system currently used in Power Plant of PLTU Tanjung Jati B Jepara is inefficient, energy efficiency in FDF is only 32% and PAF efficiency is 49.01%. Inefficiency of the air fan system is an impacted there are waste of electric energy amount of 13,352,929 KWh (13,35 GWh) a year with a financial loss of IDR 13,352,929,140. To overcome this condition, variable frequency drive (VFD) is installed which adjusted air flow as needed so that energy waste can be reduced. MATLAB simulation is proposed to analyze the VFD method. The result shows that by using VFD, 8,233,573.444 KWh (8.45 GWh) can be saved a year. Total cost benefits are IDR 8,233,573,444 as 32.1% of saving cost. Efficiency of FDF is 72.57 % and PAF is 66.84%.
2 citations