Lifting Machinery Vector Converter Applications, And Low-frequency Performance Improvement

How the velocity modulation performance of the motor is have the directly decisive influence towards raising the product mass, the exaltation labor rate of production and economical electric energies. velocity modulation had been occupy the predominant position。To 60s along with the development of the power electronic technology, just make communicate that the velocity modulation can develop quickly。Its velocity modulation performance has already can match in excellence with the performance of the speed control system of dc. mutually, there is trend of replace the speed control system of dc. In resent years, with the development of new power electronic component and computer technique, high performance AC Motor VVVF system has been applied extensively.In this paper, first, the basic technique of speed control by frequency variation is introduced, and then the operating principle of field orientation is introduced briefly, second, mechanical properties and require of control system with the crane is analyzed systematically. according to the generating theory of PWM wave, a rotate speed negative feedback control is adopted and debugged according to the design of the system.Some starting manners and mechanical properties of motor are given and analyzed in this paper. This paper analyzed close-loop variable speed system in low frequency regional characteristics, some problems in system low frequency regional is described. This paper analyzed the problem of harmonic wave and approximate square wave in running, and made the relatively the measure, and solved over loading starting. It is proved by design experiments and simulation waves that this design accords with the expectable requirements.