The Design Of High-power Inverter Drive Circuit And Rotor Frequency Control System

In construction machinery, crane is widely used, its work is frequently raise or decentralization of heavy objects, while heavy objects on the decentralization process has a very reliable potential recyclable space. To use the recyclable energy of the crane trationally, the design of drive system on crane must consider two aspects. The first aspect is the motor speed control problem, the second aspect is the energy recovery schemes. In the crane motor speed control program, for AC variable speed, in addition to frequency control, rotor frequency control also has high speed performance, especially chopping rotor frequency control system, greatly expand the speed range more importantly, its main circuit containing affinity inverter device, which can slip power back to grid. So consider joining the potential feedback program, the communication cascade speed than the added cost of frequency control less.In this thesis, for the structure of the tower crane and the actual working conditions, it uses TI's C2000series DSP2812as the core controller and adopts the string rotor frequency control to design energy-efficient motor speed control system of tower cranes. The main circuit uses rotor frequency control mode, chopper adopt Sepic converter to improve the narrow issue of step-up chopper cascade speed control speed range, especially to raise the low speed performance and design system drag and more. To further save costs and reduce the harmonic pollution, it designs a drag and more systems to complete cranes multi-agency focused coordinated control with multi-agency characteristics based of the crane. Control strategy and drive design, the inverter-driven design is as a key, the system uses high-performance DSP core controller to design the thyristor's digital drive, it overcome the shortcomings of the analog driver circuit and reduce the minimum inverter angle, and with the fuzzy control algorithm to design the motor speed control system. It analysis the Sepic working principle and control method and use the fuzzy control algorithm to complete the motor closed-loop speed control system design, combining with the characteristics of the wound rotor motor. To demonstrate the feasibility, it uses a winch as a model, a low-power simulation platform of the program is builded to be verified. The experimental results were analyzed, the experimental results consistent with the design.