Showing papers on "Variable-frequency drive published in 2007"

Intelligent pump system

Abstract: The present invention is a controller specifically for pumps, making the benefits of variable frequency drive (VFD) technology more accessible to pump users. The present invention incorporates pump-specific system optimization software, an industrial grade drive, and a menu-driven user interface, offering protection, reliability, and ease of use not possible with other variable frequency drives.

Air handler unit fan installation and control method

Abstract: A method is provided including installing a variable frequency drive unit to drive a previously non-variable air handler fan of an HVAC system. The method includes setting a control strategy for the variable frequency drive. The control strategy includes a drive speed for each mode of the HVAC system. The method includes operating the HVAC system in each mode and monitoring the HVAC system. The method includes adjusting the HVAC system or the control strategy of the variable frequency drive to increase drive speed based on monitoring the HVAC system.

Method for optimizing valve position and pump speed in a PID control valve system without the use of external signals

Abstract: The present invention provides an algorithm that utilizes flow reference data which can be mathematically determined as a function of various pump and motor parameters such as speed, torque or power or from calibrated flow curves stored in an evaluation device, or from an external flow reference such as a flowmeter. Once the PID control valve has reached its steady state condition a calculated flow value is captured and compared to the current flow value obtained after the variable frequency drive has decreased in frequency (speed). The valve position is optimized just prior to the speed threshold where the flow condition of the algorithm is no longer true.

Electric Systems For High Power Compressor Trains In Oil And Gas Applications - System Design, Validation Approach, And Performances.

Abstract: This paper presents the development process for a new variable frequency drive (VFD) system for large size compressor trains for natural gas and liquefied natural gas (LNG) applications. The paper covers the multiple steps of the product development process, from identification of applications requirements, definition of design 61 ELECTRIC SYSTEMS FOR HIGH POWER COMPRESSOR TRAINS IN OILAND GASAPPLICATIONS— SYSTEM DESIGN,VALIDATIONAPPROACH,AND PERFORMANCE

Micro-electromechanical system based switching in heating-ventilation-air-conditioning systems

Abstract: HVAC systems implementing micro-electromechanical system based switching devices. Exemplary embodiments include a HVAC system, including a load motor, a main breaker micro electromechanical system (MEMS) switch, and a variable frequency drive (VFD) disposed between and electrically coupled to the load motor and the main breaker MEMS switch.

Pump system including a variable frequency drive controller

Abstract: A pump system generally comprising an electrical connector operable to couple with an electric circuit to receive electricity, an electric motor operable to actuate a pump to pump a fluid, and a variable frequency drive (VFD) controller. The VFD controller is operable to control the rotational speed of the electric motor by providing a variable frequency signal to the electric motor to prevent the current utilized by the electric motor from exceeding a maximum current level associated with the electric circuit.

Investigation of Induction Motors Starting and Operation with Variable Frequency Drives

Abstract: Induction machines are most widely used in various industrial applications. Variable frequency drives (VFDs) provide flexibility in speed control and improve starting and operating performance of induction motors. However, investigation of induction motor starting with VFDs is not considerably carried out. In some cases motor performance is different from that expected, which causes confusion to field engineers. In this paper, theoretical derivation of starting parameters of induction motors using the equivalent circuit is conducted for cross-line and VFD starting. Cross-line starting is considered as one special scenario of VFD starting with a starting frequency of 60 Hz. An industrial distribution system in the oil field is used as a case study for the cross-line starting. Factors that could significantly affect the starting performance are studied. A two-pole squirrel-cage induction motor is used in the case study for VFD starting. The relationship between the starting frequency, starting current and required starting voltage is derived mathematically. It is found that although both starting voltage and current are functions of starting frequency the required starting voltage shows large variation at the lower starting frequency between 2 Hz -10 Hz. The induction motor torque characteristics of speed control during normal operation with VFDs are also discussed.

Rfi/emi filter for variable frequency motor drive system

Abstract: An RFI/EMI filter for a variable frequency motor drive system includes a variable frequency drive; a common mode choke; a motor; a cable including a plurality of power leads interconnecting the motor with the variable frequency drive and passing through the choke; a ground shield surrounding the cable and connected to motor ground and variable frequency drive ground; and a common mode return conductor interconnected between the variable frequency drive and the motor and disposed within the shield and passing through the choke for returning a portion of the common mode current to cancel a portion of the saturation current experienced by the choke to increase the portion of the common mode current carried by the return conductor and decrease the portion carried by the shield to reduce the RFI/EMI contributed by the shield

Double three-level inverter based variable frequency drive with minimal total harmonic distortion using particle swarm optimization

Abstract: In this paper, a suitable particle swarm optimization (PSO) is firstly proposed to obtain the pulse width modulation (PWM) switching time which maintaining a required fundamental voltage and a minimal total harmonic distortion (THD) for very high power medium voltage induction motor drives fed by a double three-level inverter (DTI). The simulation results show that double three-level inverter based variable frequency drive system needs switches with lower voltage rating, and performs lower voltage harmonics than one single three-level inverter. After optimizing the PWM switching time by using particle swarm optimization, the motor drive voltage quality improves more.

Rubber injection moulding machine energy-saving controlling device

Abstract: One kind of energy-saving control device for rubber injection molding machine includes a variable frequency drive motor, a liquid pressure and flow sensor, a temperature sensor and power supply circuit, an energy-saving control system consisting of monitoring controller, a process control module, a temperature sampling and controlling module and a variable frequency drive control module; the input and output terminals of process control module, the temperature sampling and controlling module and the variable frequency drive control module are respectively connected with the output and input terminals of monitoring controller. The control, variable frequency and energy-saving of the main parameters of the process inflow realizes the matching of load flow and solve the problem of much overflow and high energy consumption long existing in the hydraulic system of injection molding machine. Each monitoring controller is parallel connected to the same host workstation and data of each monitoring controller is checked by the monitoring software of the host to achieve the spot digital management. In addition, data can be transmitted to the control center of the host workstation through the Internet to achieve remote control energy-saving, diagnosis and maintenance services.

New motor design with conductive micro fiber shaft grounding ring prevents bearing failure in PWE inverter driven motors

Abstract: Variable frequency drives induce shaft voltages onto the shaft of the driven motor because of the extremely high speed switching of the insulated gate bipolar transistors which produce the pulse width modulation used to control AC motors in commercial industrial and even consumer applications. This voltage induced on the shaft becomes great enough to overcome the dielectric of the oil film in the bearing causing bearing discharges known as electrical discharge machining effect. Unless mitigation for these shaft voltages is employed in the motor, the motor's bearings may become damaged from the electrical bearing currents which cause pitting and excessive bearing noise, fluting and finally motor failure. The cause of this problem and commonly applied mitigation methods are discussed as well as a new and highly effective conductive micro fiber shaft grounding ring technology which resolves these problems.

Strategy Research on Dual-PWM Inverter Based on Power Feedback Integrared Control

Abstract: The direct power control strategy of PWM rectifier and the variable frequency drive system of the inverter are studied.Then the op- eration principle and the nmning characteristic of dual-PWM converter are analyzed.Because the middle DC segment volts of the inverter is fluc- tuated,the integrated direct power control strategy with power feedback is proposed to improve the dynamic response speed and anti-jamming ability.The simulation result verify the suggested scheme.

Soft ice cream machine control system

Abstract: The utility model discloses a control system of a soft ice cream machine. The control system comprises a main control board, a switch board, a drive board and a compressor. The power supply input end of the drive board is connected with the municipal power supply through a controllable transformer. The main control board, the switch board and the compressor are respectively connected with the drive board; wherein the main control board is connected with the switch board which is connected with a proximity switch. The control system also comprises a variable frequency drive module which can transforms the two-phase municipal power into three-phase pulse DC power supply; the input end of the variable frequency module is connected with the drive board and the output end is connected with the compressor. The utility model has a closed-loop control method and high temperature-control precision; wherein the temperature-control precision can reach +- 0.2 DEG C for controlling the refrigerating output of the compressor according to the environment variables. The soft ice cream machine adopting the variable frequency drive module can be reduced in noise and increased in starting torque and can run stably; by the utility model, intelligent fuzzy control is realized, the speed regulating range is widened, stepless speed change is achieved and energy is saved.

Medium voltage drives in the sugar industry

Abstract: This paper first outlines the benefits of medium voltage variable frequency drives compared to classical drivers or control methods (i.e. steam/gas turbines, hydraulic coupling and Direct-On-Line operation with, for example, valve/damper control). The paper then focuses on typical variable frequency drive applications in the sugar industry and also describes two real cases, namely an ABB drive system used in a soft-starter application at Al Khaleej Sugar Refinery, Dubai, UAE and the replacement of inefficient steam turbines for cane mill drives at Compania Azucarera Hondurena S.A, Honduras, Central America (which produced significant returns of additional 1 million U$/year). Next, the main selection criteria for a medium voltage drive system are described.