Research On Three-level Inverter System Based On Space Vector Pulse Width Modulation Technology

The energy dissipation of high voltage motor is rather magnitude in our country. If we apply the variable frequency speed regulation technology, it can bring considerable value not only in economy but also in society. Since it needs huge of money and also the tcchnology is quite difficult. 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 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 wave form. 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, isolated driving circuit by optical fiber, delay time circuit on powering, sampling circuit of current and voltage, protection circuit and etc. One method to control the neutral point potential is 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 motor load is the variable voltage variable frequency controlling method. Using MATLAB Simulation Tools complete the Circuit & System function verification. At last, the hardware and the control strategy are tested by doing experiments. A series of experiment waveforms of the whole system are given and they validate that the system is reliable.