Design And Applied Research On The High-voltage Cascaded Inverter

In recent years, multilevel converters have presented an important development to reach higher power with increasing voltage level. At present, cascaded multicell converter, diode clamped multilevel converter and flying capacitor multilevel converter are3mainly converting topologies. Among them, cascaded configuration gains many advantages as follow:input side has less pollution to the electrical net; output voltage approaches to sine wave so that it doesn’t need output filter; structure is simple and easy to be modularized; control method is easy to be realized and so on. Therefore, cascaded converter has been chosen as the research subject of this paper.The characteristic and development state are summarized in this paper. Cascaded multilevelhigh-voltage converter’s basic topology is introduced. Their respective advantages and disadvantages were analyzed carefully. Cascaded multilevel converter’s circuit structure that is often used currently is mainly introduced. The high equivalent switching frequency can be obtained with low switching frequency devices. This technique improves the equivalent switching frequency through the counteract of lower order harmonics but not simply through processing the harmonic from lower order to higher order, so that it is with a perfect performance on harmonic feature. So it is used in this paper. The emulation waveform by MATLAB is also given, the results prove the feasibility and applicability of academic analysis. For multi-modular converters and multilevel converters, the number of PWM generators provided by the IC is clearly not sufficient. In such occasion, the core of the controller is made up of Digital Signal Processor (DSP) and Complex Programmable Logic Device (FPGA) devices. DSP is used as the control core of the experiment platform, andFPGA is used as the multi-path PWM generator.The software and hardware are designed based on the carrier-based Phase Shifted PWM and the experiment circuit is set up. The output of multilevel voltage is achieved and the result is expected.