Research On The Key Technologies And Algorithms Of VVVF Based On DSP

With the rapid development of modern electronic technology, the demand for WVF power supply is increasing. Traditional WVF power supplies use analog control, which have lots of problems, such as the device easy to aging, thermal drift and so on. The emergence of high-performance DSP controller can easily achieve a flexible, precise line control and can apply a number of advanced control algorithms. DSP-based digital VVVF power supply has become the trend of power supply design.On the basis of the refrigeration compressor system project of Chinese Academy of Sciences, the key technologies and algorithms of VVVF power supply have been well studied, including SPWM generation algorithm, switching harmonic suppression technology, dead time compensation algorithm, output filter design technology and closed loop control algorithm. Relyed on the hardware platform of VVVF power supply, the paper has improved some algorithms and designed the softwares, which are embodied in the following aspects: through comparative analysis of three SPWM digital generation algorithms, the asymmetric regular sampling was selected and the software realization and algorithm improvement were given, which achieved the independent control of frequency and voltage; in the study of switching harmonic suppression, the voltage half-cycle zero switching and phase compensation solutions were put forward; in the study of dead time compensation algorithm, the current compensation of the DSP itself was used, and an improved current threshold compensation algorithm was put forward; the paper also analzed output harmonic and designed compstible output filter; finally, the implementation process of closed-loop control algorithm was discussed.In order to verify the performance of key technologies and algorithms, the paper has established a VVVF power system software and hardware test platform. The design of hardware modules was given and the program of software modules was completed. On the experimental platform, different testing laboratories were carried out. The experimental results of the analysis further confirmed the performance of the technologies and algorithms discussed in the paper.As the software platform used in VVVF power supply is front-back programming structure, it is difficult to guarantee real-time requirements of VVVF power supply. The transplantation and application process of uC/OS-II into DSP56F8346were study and multi-task design of VVVF power supply has been given, which futher improved the system’s real time and reliability.