Based DSP Digital Inverter Of VSCF Electrical Generating System

By use of electronic inverter, Variable Speed Constant Frequency (VSCF) Electrical Generating System converts variable frequency AC power from generator to constant frequency AC power. It is electronic inverter that realizes constant frequency output. So the power system has advantages of facile maintenance, high quality of output, high efficiency, flexible structure et cetera, and makes both start engine and generating electrical power dual function possible. Now it has become an important research direction of aero-power. With the development of power electrical technology and power element product technics, VSCF generating system has better foreground and more broad scope of development. And power inverter, which has important effect on the whole generating system, is the core of VSCF generating system.With the development of Digital Signal Processing technology, the system based DSP can realize flexible and precise real-time control as well as malfunction monitor by software. In the digital inverter, we adopt the technology of digital dynamic waveform correction, which can compensate the delay between control signal and output waveform, and ensure the accuracy of control. At the same time, the technology of digital DC component adjustment was introduced, by which we can exactly compensate the control signal, and realize adjusting DC component of output on the premise of output performance. Furthermore, it is easy to use different control strategy in the digital inverter, so different PWM control can be used, in order to optimize the design of output filter and improve the output performance.This paper discussed the theory of Switching-Node Preset optimal SPWM detailedly, and got the solution of 9 waves, 13 waves, and 17 waves Switching-Node Preset optimum SPWM control strategy. Furthermore, By means of raising the switching frequency, the quality of output voltage can be promoted, the resonate frequency of output filter can also be raised, which made the inverter smaller volume and lighter weight and more efficient.In order to solve the problem of voltage regulating, the control strategy of Select Harmonics Elimination Pulse Width Modulation (SHEPWM) was introduced. At the same time it was combined with optimum SPWM, the range of voltage regulating was expended and the DC utilizable efficiency was improved. With the example of 40kVA VSCF power inverter, we have carried out the solution and the simulation of SHEPWM control, and we have also achieved the whole set of this control strategy.We discussed the four-legged inverter with Space Vector Modulation (SVM) to aim at three-phase four-line output; we introduced the principle of three dimensions SVM, and attained the related control scheme. With the illustration of 15kVA VSCF power inverter, we tested and verified that the inverter system under 3D SVM control can realize the three phase four line output and linear voltage regulating.At last, by linking with the scientific research item of Variable Speed Constant Frequency Electrical Generating System under digital control, we carried out entireverification with our digital power inverter. Because of the preciseness high-speed and flexibility of digital control, the steady performance and dynamic performance of the final VSCF power under digital control have improved greatly.