The Research Of General Inverter Based On DSP

Recently, the research of variable frequency speed variation of AC motor and relevant technology has become an important issue in electrical drive field, with the appearance of new power electron apparatus and microprocessor and the development of the control theory, the technology of variable frequency speed variation will improve more rapidly.In the field of variable frequency speed variation, pulse width modulation which as a key technology has made great contribution to the development of variable frequency speed variation technology, the constant ratio of voltage to frequency (constant U/F) control is used widely in general-purpose inverter. According to this situation and on the base of variable frequency speed variation experimental platform which power is 3kW, a specimen of inverter used TMS320LF2407A DSP as its controller is designed in this paper, the control principle is constant V/F and technique of space voltage vector PWM are used, the inverter's power is 30kW.The hardware circuit and software are designed and debugged after expatiating on the work principle and design method of the inverter in this paper, in order to perfect the experimental platform from function and performance. The main content in this paper is:1. The control principle of constant U/F is introduced in this paper, the technique of sinusoidal PWM and space voltage vector PWM are compared, the characteristic of SVPWM is analyzed especially.2. The principle of low frequency and DC voltage dynamic compensation of VVVF general inverter are studied, and the method of implement is presented.3. The method and arithmetic of signal sampling of general inverter are introduced, including DC and AC sampling. In order to meet the demand of real-time and timely character of signal sampling, AC sampling is adopted and the implement method of AC sampling based on frequency tracking is put forward.4. The common faults and protective principles of general inverter are analyzed, protective measures by use of hardware and software are taken to eliminate faults, as a result the reliability of the system has been greatly improved.5. The man-machine interactive system is perfected, the parameters and running condition can be displayed in LED, such functions as parameters setting, running control etc can be finished by the keyboard.6. The DSP TMS320LF2407A of TI is used as controller and design the hardware circuit and software. The hardware circuit include the main circuit, controlling circuit, voltage and current sampling circuit, protecting and fault dealing circuit, the man-machine interactive system; The structured programming design's method is applied in the whole system software, which makes debug and compile program very easily and conveniently and achieves the basic functions of general inverter. The main program and function subprogram are designed.7. The works that have finished perfect the AC variable frequency speed variation experimental platform of author's laboratory has owned further.8. It has been proved by the results of tests in the laboratory that the performance and functions of system have achieved the design's request.