Research On Three-level Inverter Based On Tms320f2812

With the fast development of modern power electronics and digital control theary, multi-level inverter attracted more and more attention, and has become a hot research issue both at home and abroad. In the AC or DC power conversion, AC motor with high voltage and large capacity for variable frequency speed control, power quality analysis and other fields, multi-level inverters have been widely used.Related to the traditional two-level inverter,multi-level inverter has low output voltage harmonics,low switching devices stress,low switching frequency,low switching loss,and high inverter efficiency.This paper describes the topology and operating principle of the diode clamped three-level inverter.The principle of traditional three-level inverter SVPWM algorithm is analyzed. According to the disadvantages of a lot of calculation of the trigonometric functions and the estimation of the sectors, the traditional SVPWM algorithm is improved by using 60°coordinate system. The sector's judgments, the synthesis of reference vector, the calculation of action time are greatly simplified, and the implement of digital control are become easier.In order to lower the switching loss and avoid the abrupt change of output voltage vectors, an optimal SVPWM algorithm based on the 60°coordinate system is proposed, it makes use of seven-vectors modulation in which the positive(or negative) small vectors are used as the first output vector. The strategy of changing the voltage adjusting coefficient to adjust the effective time of the positive and the negative small vectors to control the neutral point potential balance is proposed, which is based on the detection of the direction of the current of the load and the voltage of the capacitance.Through the building of the Matlab simulation model, three-level inverter SVPWM algorithm based on 60°coordinate system proposed in this paper are verified.On this basis, a diode clamped three-level inverter experimental is built by TI's DSP chip TMS320F2812. The minimum system board of TMS320F2812, diode clamped three-level inverter main circuit, drive circuit and signal detection circuit are designed.The effectiveness and superiority of the strategy proposed in this paper are verified by experiment results.