The Development Of Controller Of Cascade High Voltage Inverter

Energy shortage and environmental pollution are two globally concerned problems, saving our world from energy outage by conserving energy sources needs the endeavor of entire society. Nowadays industry requires enormous amount of air-blowers, water pumps, compression engines, etc. which leads to the major significance of developing and applying high-voltage multi-level frequency converting and energy saving devices to the reduction of our nation’s energy consumption. Power unit cascaded multi-level converter reveals its characteristics like low harmonic pollution towards the grid, improved factor of input power, better output waveforms, thus possesses overwhelming advantage in the field of high-voltage frequency converting and speed controlling.This paper started from the principle of the frequency converter’s speed control, first introduced the development status of high-voltage frequency converting and speed controlling technologies, the general types of high-voltage frequency converting and speed controlling, the analysis on of the topology of cascaded high-voltage frequency converting circuit, topology and mechanism of the power unit; compared with two-level and three-level frequency converters, cascaded converters has more output voltage levels, smaller voltage gradient changes, greater similarity between output waveform and sinusoidal waves. This paper also studied in detail the control strategy of several kinds of multi-level converters, analyzed and compared strategies such as Sine Pulse Width Modulation (SPWM), Space Vector Pulse Width Modulation(SVPWM), then goes on with an theoretical analysis of carrier-based phase shift SPWM with mathematics by making an incision from its technical principle and mechanism. This includes harmonic analysis, coherence between carrier phase shift angle and cascading number, coherence between carrier phase shit angle and output performance. This paper also proposed carrier-based triangular modulation mechanism, based on the sinusoidal wave amplitude modulation method; the triangular modulation uses a calculation method that significantly reduces the computation load of MCU. We built a simulation model of the cascading high-voltage frequency converter system, gave detailed process of encapsulation and modeling; applying carrier-based phase shift SPWM technique as control method, we conducted simulation and verified our predictions in our theoretical analysis. At the same time we validated the equality between traditional sinusoidal wave amplitude modulation and carrier-based triangular amplitude modulation. Finally, combining with time division multiplexing technique, we presented the design of the central control chip of cascading high-voltage frequency converter, with details of parts of the circuit’s hardware and software designs. Also we gave per-module illustration of the detail mechanism on implementation of FPGA of multiplexing high-speed SPWM trigger circuit, appended with some of the VHDL program source code. The result of our design gave well-formed waves in experiments, and satisfied performance demands in field tests, thus proved to be highly applicable in field scenarios.