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.

A Controller Development Based on PLC for Climate Control of Agricultural Greenhouses

Abstract: Forced ventilation has more accuracy in climate control of agricultural greenhouses. It is worthwhile to apply some energy saving measures to overcome the disadvantage of high power consumption in fan driving of forced ventilation. Here we present a new developed controller based on PLC which mainly can control the ventilation fans rotation speed in combination with variable frequency drive except for manipulating other facilities in greenhouse like pad, shading screen etc. The control system integrates a sense module which measuring solar radiation, temperature and humidity inside and outside of greenhouse, an actuating module which includes variable frequency drive, pad control and radiation screens to perform a optimized cooling strategy to reduce electrical energy consumption by low down the fans rotation speed with ambient condition changes.

Analysis of VFD Induction Motor Current Disturbances by Prony Analysis and Motor Redesign by Intelligent Optimization Techniques

Abstract: An analytical approach is discussed in this paper to minimize the influence of disruptive current spikes occurring at low frequency in a Variable Frequency Drive (VFD) induction motor. In a continuous process industry a 3-phase, 550 kW, induction motor coupled with a reciprocating pump, is tested at low frequency. Prony method is used to analyze the data. The optimal values of motor design parameters that deliver sufficient mechanical power at low frequency and cause the least disruptive current spikes is arrived at, by using intelligent optimization techniques like Artificial Bee Colony (ABC), Particle Swarm Optimization (PSO), and Genetic Algorithm (GA). Using the optimal design values obtained, Taguchi method is applied on the VFD control parameters. The optimal control parameters thus obtained for tuning the VFD to get the minimal current spikes is comparable with the practical VFD parameters which is seen to be able to deliver stable operation of the motor at low frequency. The optimal motor design parameters can be used to procure a new motor that can give stable operation at low frequency.

System for robust sliding mode control of an ac motor

Abstract: The present invention relates to a system for robust sliding mode control of an AC motor, in which a variable frequency drive is used as final control element. The control action is executed by a controller which executes the sliding mode control algorithm.

Anti-overvoltage-stall control method for variable frequency drive systems

Abstract: The invention relates to an anti-overvoltage-stall control method for variable frequency drive systems. The method is characterized in that in the speed-reduced running process of an asynchronous motor in a drive system, the changes of voltage values of the two ends of a direct-current energy storage unit in the drive system are detected through a frequency converter control unit, when the voltage values rise to a preset anti-stall voltage value, the frequency converter control unit remembers an original output frequency and calculates an off-set frequency between a stator and a rotor of the asynchronous motor at the same time, and the sum of the original output frequency of a frequency converter and the off-set frequency is taken as the output frequency of the current frequency converter and keeps unchanged, so the rise of the voltage values of the two ends of the direct-current energy storage unit can be suppressed, and the voltage values are always changed in a range lower than an overvoltage reference value of the frequency converter, thereby avoiding the situation that the frequency converter skips over voltage protection or the frequency converter is damaged.