Showing papers on "Variable-frequency drive published in 2011"

Submersible pump system

Abstract: A submersible pump system includes a submersible pump assembly having one or more stages of impellers and a submersible motor assembly that drives the pump assembly. The submersible pump assembly includes a motor housing, a motor within the motor housing for driving the pump assembly and a control module mounted to the motor housing for operating the motor. The control module is electrically connected to a power line and comprises a controller and a variable frequency drive driven by the controller. The controller operates the variable frequency drive to drive the motor to maintain a constant pressure output condition from the pump assembly.

Variable frequency drive bypass energy savings

Abstract: A Variable Frequency Drive (VFD) supplies power to rotate a motor, controlling both the speed and direction. The method normally used for this power conversion by the VFD results in energy losses and line harmonics. When the motor is driven by the VFD to be rotating at the same speed and direction as if the motor was straight across the incoming AC power, a transfer in power supply to the motor can be made using contactors to bypass the VFD. When in this bypass mode, the energy losses of the VFD are greatly reduced, and the line harmonics due to the VFD are greatly reduced. When it is subsequently recognized that the speed reference has deviated from being the same speed and direction as if the motor was straight across the incoming AC power, a transfer in power supply can be made from using contactors to once again drive the motor from the VFD.

System and method for controlling fluid pumps to achieve desired levels

Abstract: A system for attaining and maintaining a pre-determined fluid level in a petroleum-producing well having a pump, such as a progressive-cavity pump, and a pump motor having a variable-frequency drive control using two sensors: a pump pressure sensor located at the pump depth and a casing pressure sensor located at the casinghead of the well. A programmable computer is connected to the first and second pressure sensors and the motor speed control so that the programmable computer controls the operation of the pump motor to attain and maintain a target fluid level in the well over a predetermined time interval for reaching the target fluid level in the well. The programmable computer computes an error signal to control a variable frequency drive motor, where the error signal is computed periodically from the difference between in the actual fluid level in the well and the target fluid level in the well according to a rate reference curve. In general, the rate reference curve is generated according to an exponential or hyperbolic function.

Power Input Device with Current Pulse Multiplier Transformer to Reduce Harmonic Currents in Converter/Inverter Circuits and Devices, and Method of Making the Same

Abstract: A power supply device comprising an advanced harmonic current quashing (AHQ) and current pulse multiplier (CPM) (AHQ/CPM) three-phase transformer having: a primary winding placed around a magnetic core and having three primary winding input leads to connect a three phase power supply; and a plurality of secondary windings placed around the magnetic core in a predetermined winding turns configuration to generate a plurality of three phase outputs, where each three phase output of the plurality of three phase outputs has a different phase angle from all other three phase outputs, with each unique phase angle associated with a three phase output of a corresponding secondary winding being determined based on the winding turns configuration utilized for the corresponding secondary winding. A variable frequency drive (VFD) having 3N converters/inverters coupled to the secondary windings outputs exhibit substantially reduced harmonic currents and a current pulse number of greater than 6N.

Performance Improvement of DTC for Induction Motor with 12-Sector Methodology

Abstract: Direct Torque Control (DTC) is an advanced computation speed control method and is possibly the best among the techniques for variable frequency drive. Because it does not need axes transformation and voltage decoupling blocks. DTC provides direct selection of voltage vectors according to the error obtained and allows direct and independent control of flux linkage and electromagnetic torque by the selection of optimum inverter switching modes. Based on the estimates of flux position and instantaneous errors in torque and stator flux magnitude, a voltage vector is selected to restrict the torque and the flux errors, within the torque and flux hysteresis bands. In the conventional DTC the circular locus is divided into 6 sectors and a total of 8 voltage vectors are used. However, the discrete inverter switching vectors cannot always generate exact stator voltage required to obtain the demanded electromagnetic torque and stator flux linkages. This results in production of ripples in the flux as well as torque. In this proposed work, neutral point clamped inverter is combined with 12 sector methodology. At present, the researchers have used all the 27 voltage vectors available in the 12 sector methodology. But in this proposed work the new switching table is constructed by using only 12 voltage vectors which includes large, medium and zero voltage vectors. The usage of 12 voltage vector gives satisfactory performance as compared to usage of all the 27 voltage vectors. The performance of the proposed work is also compared with classical DTC and 12 sector methodology with 27 voltage vectors. The simulation is performed in MATLAB / SIMULINK environment.

Motor selection for centrifugal pump applications made easy

Abstract: Due to the renewed interest in energy saving, it has become more popular to utilize Electrical Variable Frequency Drives (EVFD) to power pumps which results in significant energy savings versus mechanical means for adjusting the flow of the pumping system. Due to the characteristics of pumps it is easy to misapply motors in EVFD pump applications. This paper will present some of the characteristics of the frequently used pumps and how these characteristics affect the motor selection (speed, torque and power ratings). Included will be real life examples of some often made mistakes in selecting the correct motors for these pumps. Primarily this discussion will be in regard to centrifugal pumps.

Slow turning drum for a miner

Abstract: Methods and systems for turning a cutting drum of a mining machine at a maintenance speed. One mining machine includes a cutting drum with a plurality of bits mounted on the drum and a cutting drum turning mechanism. The cutting drum turning mechanism includes a power source, a cutter motor, a switch, and a variable frequency drive. The state has a first and a second state. The first state electrically couples the power source and the cutter motor to operate the cutting drum at a cutting, and the second state electrically couples the variable frequency drive and the cutter motor to operate the cutting drum at a maintenance speed less than the cutting speed.

Intelligent frequency-variable constant-pressure water supply system

Abstract: The utility model discloses an intelligent frequency-variable constant-pressure water supply system comprising a hot water circulation mechanism. The hot water circulation mechanism comprises a water storage tank, a motor pump set and a user terminal, wherein the water storage tank, the motor pump set and the user terminal form a hot water loop. The water supply system also comprises a control center, a PID regulator, a variable frequency drive and a pressure transmitter, wherein the control center is connected with the PID regulator, the pressure transmitter detects the pressure data of the pipe network of the hot water circulation mechanism and sends the pressure data to the PID regulator after A/D conversion of the pressure data is carried out, the PID regulator corrects and adjusts the pressure data, performs PID calculation on the pressure data, and feeds back PID calculation results to the variable frequency drive, and the variable frequency drive controls the motor pump set based on the PID calculation results so as to minimize the pressure fluctuation of the pipe network. The water supply system enables constant pressure water supply and is high in automation level, reliable and stable in performances. Moreover, the water supply system runs automatically and is highly effective and energy saving.

Energy feedback device based on power unit cascade type high voltage frequency converter

Abstract: The utility model relates to the technical field of power electronics, in particular to an energy feedback device based on a power unit cascade type high voltage frequency converter. The energy feedback device comprises a control circuit, a rectification circuit, a middle DC (direct current) voltage circuit and an inverter circuit, wherein the rectification circuit adopts IGBT (insulated gate bipolar translator) power devices to form a three phase PWM (pulse-width modulation) rectifier, the other units of the rectification circuit adopt 6 diodes to form a three phase bridge type uncontrolled rectification circuit, and the inverter circuit adopts IGBTs to form a single phase H type bridge circuit. The energy feedback device based on the power unit cascade type high voltage frequency converter solves the pumping voltage problem in DC bus bar in operation of power unit level cascade type high voltage variable frequency drive through a concise and economical main circuit, meets the requirements of four-quadrant operation of various motor loads, has good energy saving effect, lowers the fabrication cost of a power unit, and has high economical efficiency.

Design Strategy for a 3-Phase Variable Frequency Drive (VFD)

Abstract: This paper describes the design processes for a 3-Phase Variable Frequency Drive (VFD) as broken up into two stages: The AC-DC converter and the DC-AC converter. It acknowledges three (3) design versions, all. The output of the motor drive is 3-phase pulse width modulation (PWM) ranging in possible operation frequencies from 0Hz to 13kHz. The frequency control circuit uses an Arduino Uno based of the ATMEGA 328p.

Passive harmonic filter for power distribution systems

Abstract: A subsea power distribution system includes a three-phase AC power source; multiple variable frequency drives having inputs and outputs, with their inputs connected to the AC power source; an electric motor connected in series to the output of each variable frequency drive; and a passive harmonic filter system having its input connected, in parallel with the variable frequency drives, to the AC power source. The filter system includes multiple harmonic filters, each harmonic filter tuned to a specific harmonic frequency. Each harmonic filter includes a plurality of sub-filters. Each sub-filter includes a reactor connected in series to a main capacitor and one or more detuning capacitors. Each of the multiple harmonic filters is tuned to a different specific harmonic, and includes sub-filters also tuned to the same respective harmonic, and each sub-filter is sized to equally share the kVAR load of its respective harmonic filter.

Paradigm shift in proper selection criteria of VFD cable for variable frequency drives

Abstract: Power cable between the inverter and motor is a key component in the drive-motor assembly and is regularly overlooked. This paper describes a new solution for cables used with Insulated Gate Bipolar Transistor (IGBT) Variable Frequency Drives (VFD's). A new cable solution that includes the use of new connector & termination kit that will produce an overall better result and superior performance of the VFD installation. The complete cable system consists of cables specifically designed to build in all the optimum components along with matching connectors. The connectors provide a 360° contact and maintain a continuous low impedance path on the cable's shield from the motor to the drive or drive cabinet to avoid leakage of stray currents. This prevents shaft and bearing currents in the motor and gearbox. VFD systems present a different set of requirements for cable components, and this article focuses on how wire and cable fit into reliability and sustainability of a process that can impact the bottom line of any operation.

Variable frequency drive device

Abstract: The utility model provides a variable frequency drive device used for a first motor, a second motor and a third motor The variable frequency drive device comprises a first frequency converter, a second frequency converter, a circuit breaker and a plurality of disconnecting links, wherein the first frequency converter is electrically connected with the first motor through a first disconnecting link, the second frequency converter is electrically connected with the second motor through a second disconnecting link, the circuit breaker is electrically connected with the third motor, and the plurality of disconnecting links are respectively connected between the first frequency converter and the third motor, the second frequency converter and the third motor, the circuit breaker and the third motor, the circuit breaker and the second motor as well as the circuit breaker and the first motor The variable frequency drive device can meet the requirements of regular alternation of the three motors, working frequency standby and equilibrium running, thereby the using flexibility and utilization ratio of the motors being increased

Variable frequence drive and rotation speed searching apparatus for an induction motor

Abstract: Provided is a variable frequency drive and a rotation speed searching apparatus for an induction motor incorporated therein. The rotation speed searching apparatus is featured by scanning the rotor frequency of the induction motor and determining either the error between a detected DC-bus voltage and a set DC-bus voltage or the error between a detected output current and a set output current, so that the rotation speed of the induction motor can be searched out.

Cyclonic dust collector with variable speed drive and constant load current

Abstract: A dust collection arrangement employs a variable frequency drive to supply AC to its fan motor. A current sensor measures the current drawn by the motor, and this is compared with a preset value. The variable frequency drive adjusts the frequency of the AC applied to the motor to maintain the motor current at the preset level. This keeps the flow of air in the system optimal as dust producing tools are added or taken off.

Deadbeat control with multi-sampling compensation for medium-voltage motor drives by cascaded multi-cell inverter using FPGA based hardware controller

Abstract: Multi-cell inverter include an array of single-phase inverters capable of handling higher voltage ratings with lower rating power electronics devices. In this paper, a deadbeat control combined with a multi-sampling compensation method is proposed to control a Variable Frequency Drive (VFD) fed by a multi-cell inverter and realize real time digital feedback control using FPGA based hardware controller. This digital control is characterized by a very fast transient response, low switching losses, and a proper compensation for load disturbances and cyclical fluctuations.

Applications of SR Drive Systems on Electric Vehicles

Abstract: As the continuous growth of global vehicle production and owned, the problems brought by vehicles are conspicuousness day after day. These problems are much more serious in China. Thus developing zero emission electric vehicles have become the main scientific research projects in many countries around the world in 21st century. Energy-saving motor drive technology has become one of the key points to the EV commercialization. In the present electric vehicles, there are several main drive systems include the chopping system of DC motor, the variable frequency drive system of induction motor(IM), the drive system of permanent-magnet motor(PM) and switched reluctance drive system(SRM), etc. The DC machine has been faded gradually in the electric vehicle drive system for the reason of high startup current, huge volume, low efficiency and poor reliability. Even worse, the carbon body and the commutator which are not suited for high speed movement need to be changed frequently. The variable frequency drive system of IM has a small torque fluctuation, but with low efficiency especially in the low speed stage. When the electric vehicle is grade climbing, the torque output is small and the current is high. Although the permanent-magnet motor is of high efficiency, the manufacturing technique is very complicated and the machine will lose effectiveness because of the demagnetization in high temperature. So it is not the perfect way. The structure of the SR Motor is firmly and stable. The SRD system has a high reliability, wide range of speed regulation, high efficiency, low startup current and large torque output, all of which are especially suited for the work condition of the electric vehicles. The application of SRD on electric vehicles is affected by the torque fluctuation and strong noise. In a word, performance comparisons of the three motors are indicated in the following table 1. Because of its own characteristics,electric vehicles motor drive system should meet the following demands: 1. Output a large torque under base speed to meet the requirement of starting, accelerating, climbing and some other complicated working conditions. 2. Output constant power above the base speed in order to adapt max speed, overtaking and so on. 3. Maximize motor efficiency over the whole speed range to extend endurance mileage. From the table, the SRM has more advantage than the other motors. Many control different strategies have been proposed for the torque fluctuation task . Full rotor pitched insulating non-magnetic colloid techniques of SRM and SRM fuzzy logic

Comparative Study of Slide Valve and Variable Frequency Drive for Screw Compressor Control System

Abstract: Disha K. Shah H. K. Patel I. SCREW COMPRESSOR An oil ooded screw compressor consists of male and female a rotor which is mounted on the bearing to x its position on rotor housing. Basic shape of the rotor is screw threaded. Fig.1 fundamental operation of screw compressor The driving device is normally connected to the male rotor and it will drive the female rotor using an oil lm. In some designs driving device is connect to the female rotor, to produce higher rotor speed thus increasing displacement. But this design increase loading effect on the rotor which overall reduce the rotor life. Fundamental operation of screw compressor is just like a volume reducing device. In this process gas is compressed by pure rotary motion of intermeshing male-female rotors. Gas is travelled from top to bottom. Fig.1 shows the fundamental operation of screw compressor [1]. The process of compression of gas inside the screw compressor can be divided into ve different stages that are, (a) Suction of gas, (b) Beginning of compression, (c) Full compression of trapped gas, (d) Beginning of discharge, (e) Discharge of fully compressed gas. The capacity control of the screw compressor is carried out by means of different techniques in which Slide valve control and variable frequency control are the most widely used techniques. II. SLIDE VALVE Screw compressors typically employ slide valve arrangements by which the capacity of the compressor is controlled over a continuous operating range. Slide valve is mechanical device. The position of a slide valve belong to a screw compressor for a refrigeration system is controlled using a gaseous medium. In that priority is given to the gas whichever is at the higher pressure. Preferred source is refrigerant gas. The multiple sources of such gas are connected to a solenoid valve and it will allow the gas to act on the piston. Piston is connected with the actuator and this joint mechanism will control the position of the slide. Opening and closing of the solenoid valve is controlled through the controller. Hydraulic actuation of the piston can also be used to control the position of the slide valve. The valve portion of a slide valve assembly is disposed within and constitutes a part of the rotor housing. Working chamber of the compressor is de ned by the certain portion of the slide valve assembly and rotor housing. Fig.2 depicts mechanical construction of slide valve. Fig.2 Construction of slide valve Fig.3 Functional characteristics of slide valve Full load, Part load, Screw compressor, slide valve, VFD

AC Power Unit Operating System For Emergency Vehicles

Abstract: An AC operating system has an electrical distribution panel; a variable frequency drive control unit having a first variable frequency drive and a second variable frequency drive; a hydraulic oil heat exchanger; and a hydraulic power unit. The hydraulic power unit includes a housing having a first electric motor connected to the first variable frequency drive and a second electric motor connected to the second variable frequency drive. A first pump and valve assembly is connected to the first electric motor and a second pump and valve assembly is connected to the second electric motor. A motor start command is transmitted from the electrical distribution panel to at least one of the variable frequency drives. The variable frequency drive controller ramps up power to the selected motor to begin rotation of the motor to a predetermined operating speed in a predetermined amount of time.

Pump station combined control based on high-voltage electric drives

Abstract: The construction of a combined system of pump-station control based on a high-voltage frequency-regulated drive and high-voltage soft-start system is described. It is shown that, using special algorithms in control systems allows one to implement a very efficient and reliable technological complex with high performance capabilities at minimal cost.

Application of ABB Inverter in New High-Pressure Slurry Pump Coal Slurry Gasification Variable Frequency Drive

Abstract: The ABB ACS800 series drives in the new coal-slurry gasification technology in high pressure slurry pump application of variable frequency drive were analyzed.Selection,wiring,debugging,operation and maintenance of inverter were described.Application of the inverter,improved production efficiency,reduced matintenance and operation costs.

Flywheel energy storage motor device with changeable power supply structure

Abstract: The invention provides a flywheel energy storage motor device with variable power supply structure, which mainly solves the technical problem of improving device reliability, lowering cost and the like. The flywheel energy storage motor device adopts the following technical scheme that the stator windings of the motor are a group of independent Y windings, wherein one winding is a reversible winding, and the rest windings are a first power-generation winding and a second power-generation winding; the reversible winding is respectively connected with a variable frequency drive unit or a first-phase rectifier and a third-phase rectifier by a bilateral switch; and the first power-generation winding and the second power-generation winding are respectively and correspondingly connected with a second-phase rectifier and a third-phase rectifier. When the motor device is motor-driven, a power supply and the reversible winding are conducted by the variable frequency drive unit and the bilateral switch, and the motor drives a flywheel to rotate and store energy. During power generation, the flywheel releases energy, each Y winding simultaneously generates power and operates, instantaneous high-power output is carried out by rectification and inversion, and the flywheel energy storage motor device is suitable for various devices.

Energy Feedback Synchronous Motor Test System

Abstract: An synchronous motor test system was introduced,and a detailed account on software and hardware structure of the system was given.This test system adopted S7-300 PLC and Siemens S120 frequency converter,which could improve automatic degree and reliability.Energy feedback technology was introduced in this system,and the electrical energy was fed back to DC link to be used circularly.The result of load test indicated the system save energy obviously and was convenient for users.

Anti-interference high voltage VFD (variable-frequency drive)

Abstract: The utility model discloses an anti-interference high voltage VFD (variable-frequency drive). The VFD comprises a phase-shifting transformer, a power unit connected with the phase-shifting transformer and an MCU (main control unit) connected with the power unit, wherein the power unit is connected with the MCU through optical fibers; and I/O interfaces of the MCU are anti-interference I/O interfaces. According to the VFD, the power unit is connected with the MCU through the optical fibers, and the I/O interfaces of the MCU are anti-interference I/O interfaces, so that the anti-interference capability is extremely strong, the signal transmission is very stable, high voltage and low voltage can be fully separated, and great guarantee is brought for the safety of equipment.

Double-motor two-dimension integrated three-phase asynchronous hub motor and variable-frequency drive control system

Abstract: The utility model provides a double-motor two-dimension integrated three-phase asynchronous hub motor and a variable-frequency drive control system, wherein, the hub motor is composed of two three-phase asynchronous variable-frequency motors. The hub motor adopts two integration methods: the first method is that the two motors are respectively arranged on the left and the right sides of the rear wheel of a two-wheel electric vehicle; and the second method is that the two motors are respectively arranged on the front and the rear wheels of the two-wheel electric vehicle. Moreover, the hub motor can operate in three different ways, and has the advantages of excellent working environment adaptability and energy-saving effect. The hub motor is further combined with a variable-frequency drive controller to form a novel electric drive system for the two-wheel electric vehicle, which has the advantages of variable-frequency energy saving, regenerative braking energy saving, and substitution of motor plugging for mechanical friction braking, etc.

Study of multi-motor belt system's synchronization compensation control based on current feedback

Abstract: This paper mainly focus on speed synchronization and power balance control in multi-motor belt conveyer system when the variable frequency drive of the motors working in the constant voltage and frequency ratio mode. And the synchronization compensation control proposal based on current feedback is proposed. In order to get the exact result in simulation, the load torque model versus speed is established, the simulation results prove that this proposal is feasible. The experiment system is in master-slave mode, the experiment data and wave forms prove this proposal can be used in industrial application.

K-rated transformers and active power filter for harmonic conditioning in industrial and commercial applications

Abstract: Harmonic problems are common not only in industrial applications but in commercial buildings as well This is primarily due to the switched mode power supply (SMPS) and variable frequency drives A K-rated transformer is one which is used to deal with harmonic generating loads K-rated transformers are sized appropriately to handle the additional heat produced by harmonic component The Active Power Filter uses power electronic switching to generate harmonic currents that cancel the harmonic currents from a non-linear load The harmonic current is considered as the reference current and switching signals for the VSI are generated VSI will generate the required compensation current In this paper SMPS were analyzed for harmonic analysis Two techniques, K-rated transformer and active power filters, are considered and compared K-Rated transformers do not mitigate the harmonics, but protect the transformers from overheating The active filters mitigate the harmonics

Drive controller for a vibratory feeder

Abstract: A vibratory feeder includes a vibrator and a variable frequency drive. The vibrator includes an inductor coil and an armature. The inductor coil, when energized by a current, attracts and displaces the armature to perform mechanical work. The variable frequency drive powers the vibrator and includes an inverter, current-blocking device, and capacitor. The inverter includes a DC bus and generates a relative sine wave current including positive half-cycles energizing the inductor coil and negative half-cycles whereby the inductor coil is de-energized. The current-blocking device is connected in series with the inductor coil and blocks current to the inductor coil during the negative half cycles. The capacitor is connected in parallel with the DC bus and captures a portion of a counter EMF resulting from de-energizing the inductor coil during negative half-cycles. The capacitor discharges the captured portion of the counter EMF to reenergize the inductor coil during subsequent positive half-cycles.