On The Key Technologies Of High Performance Variable Frequency Adjustable Speed Drives

The work in the dissertation centered on some key technologies of high performance variable frequency adjustable speed drives, i.e. sensorless control and efficiency optimization control.The phylogeny and the trend of ac speed adjustment technology were explained. It laid stress on the review and the prospect of the sensorless control technology and the efficiency optimization control technology.Because all the simulation models of induction machines available now, which are provided by the various kind of simulation softwares, are ideal models. These models can not meet the need of the study. The simulation model considering the nonideality of the motors based on MATLAB were established specially, including Simulink subsystem models, M-file S-function models and C MEX-file S-function models taking iron loss and variable parameters into account. The proposed models provided a more accurate approximation to actual induction motors for many control problems of induction motor drives.Whether the computational burden of the EKF can be reduced through reducing the order under the condition that the speed estimation accuracy is not decreased was explored. The algorithm of the reduced order EKF was developed and a method of processing signal differential was proposed. The conclusions were obtained via the comparison of the simulation results and the experimental results.Speed estimation of induction machines based on the new members of the Kalman filter family — Unscented Kalman Filter (UKF) and Square Root Unscented Kalman Filter (SRUKF) were discussed in depth. Answer the question whether the better speed estimation performance can be gotten if the UKF and the SRUKF were introduced. The effect of the sampling time and the parameters of the filter upon the speed estimation performances are analyzed, and the various aspects of the speed estimation performances of the filters, such as stationary error, dynamic response speed, parameter sensitivities and algorithm complexity are evaluated. Some conclusions were drawn.Aiming at how to realize energy saving control on the VVVF general inerter products without increasing any hardware cost, a fuzzy efficiency optimizing control scheme was selected according to the hardware and the software resources of the inverters. Finally, the scheme was implemented on the platform of the original general inverters.