Research On Variable Frequency Speed Regulating AC System Based On Three-level Inverter

The energy dissipation of high voltage motor is very serious in our country. If we carry out the variable frequency speed regulation, it can bring considerable value not only in economy but also in society. But it needs a lot of money and the technique is very complex. Today the products used in our country are almost come from abroad, which are expensive and have no property rights of our own. So, it is imperative under the situation to develop the speed regulation products of our own.The multi-level inverter is a circuit topology proposed in the early 1980s particularly applied in the high voltage variable frequency speed regulation area. It has the characters of reducing the switch stress and improving the quality of output waveform. Together with the appearance of the excellent digital signal processor (DSP) makes the application of multi-level inverter come into being.Based on studying of the multi-level technique, a variable frequency speed regulation system based on the diode clamped three-level inverter is introduced in this thesis in detail. It includes ac-dc-ac main power circuit, snubber circuit, isolated driving circuit by optical fibre, delay time circuit on powering, sampling circuit of current and voltage, protection circuit and etc.A distributed power system(DPS) which can reinforced the system's security is developed to solve the power supply of the whole system.Two methods to control the neutral point potential are proposed in this thesis which can solve the neutral point potential problem owned by three-level inverter.Besides, a control system with TMS320LF2407 as the core is introduced in this thesis. The strategy to control the three-level inverter is the space vector pulse width modulation. The speed regulation of the...