| This thesis discusses an effective method to achieve the waveform control of sine-wave inverter power supply. The whole system consists of hardware circuit and software design. It is the aim for the system to design a sine-wave inverter power supply with low cost, high-fundamental frequency, single phase, and miniwatt of 50Hz.For hardware design, two low-end AVR ATmega8 microcontrollers can be used in the structure. Based upon advantages of microcontroller, two microcontrollers, one as main chip and another assistant chip, can share out the work and cooperate with one another in the system, in which main chip undertakes sampling and analysis of waveform, following by ordering assistant chip to output SPWM with different waveform according to the analysis results. As a result, the aim to control waveform can be achieved. Additionally, the design adopts the plan on exportation of double-line PWM, and thus, to some extent, simplifying the overall circuit and reducing the hardware cost. Besides, photoelectricity separation technique can be used to fully ensure the security and reliability of system.For software design, the design finds a whole set of ways to achieve the close-loop control on analysis of waveform sampling, extraction of coefficient of variation and modulation of exporting waveform, which including sampling of waveform, finding of phase-position null point, extraction of intact half-wave data, normalization of data, drawing of coefficient of waveform variation. Through this, the system wishes that voltage waveform of the load can be as close to standard sine-wave as possible.The main aim for this design is to attempt to find out a method to achieve the waveform control of sine-wave inverter power supply, accompanying the verification of algorithm. Through the coordination between hardware circuit and software design, a control algorithm based on simulation of exporting waveform can be achieved in the system. |
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