| The inverter technology is contrary to the rectification technology. An inverter is a device which transforms direct current into alternating current. According to the output waveform, inverter can be divided into square wave inverter and sine-wave inverter. Currently most load demand input for sine wave, so sine wave inverter get more and more attention. The most important part of sine-wave inverter is the control circuit. Sine-wave pulse-width modulation (SPWM) which uses sine wave as modulation wave and triangular wave as carrier wave is a key technology which based on the theory of pulse-width modulation.In this paper, the structure and principle of the inverter are analyzed at first. Then a DC-DC-AC two-stage high frequency inverter is designed:The input voltage12V DC boost to370V DC using a push-pull circuit; Then the370V DC is turned into220V/50Hz AC using a full bridge circuit. The control circuit of the push-pull circuit is based on a PWM (pulse width modulation) control chip SG3525. According to the characteristics of the circuit, the output of this stage is not settled so as to simplify the filter circuit; The full bridge circuit is conventional. The method of the full bridge control circuit is the SPWM (sinusoidal pulse width modulation) method. The frequency of the SPWM wave is two times of the carrier frequency so that the modulation circuit is simply and the output filter circuit design become easier.By analyzing and calculating the circuit parameters and making inductance and winding components, this paper designed a DC-DC-AC two-stage high frequency inverter. After installing and debugging it, I eventually get the experimental results and waveform which confirmed the feasibility of the design. |
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