The Design Of Photovoltaic Inverter In Acoustic Alarm Controller

Power supply is an important part of civil air defense alarm system. It’s theimportant guarantee for the civil air defense alarm controllers to work properly. Mostof China’s air defense alarm system uses a single supply mode of commercial power.As this supply mode is susceptible to the fluctuations in power grid, the air defensealarm system is not able to give a alarm in case of disaster timely, what’s worse, itmay be paralyzed. Considering this shortcoming, a photovoltaic inverter is designedas the standby power in civil air defense alarm controller. When the commercialpower is cut off, this photovoltaic inverter can be used to supply ceaseless power tosend the alarm signals timely and reliably.At first, features of a few of representative inverter systems structures areanalyzed. According to photovoltaic inverter principle, performance and the fact thatthe air defense alarm system networks decentralize, we combine the push-pull circuitwith high frequency boost and full-bridge inverter, and make the main circuittopology of this design. Then the photovoltaic power generation principle andequivalent circuit is studied, the mathematical simulation model is built. The outputcharacteristics of the photovoltaic power circuit are analyzed through the simulationand the maximum power point tracking algorithm is proposed. At last, thephotovoltaic inverter system based on MSP430F249is designed. It contains2parts,the DC-DC high-frequency push-pull booster and DC-AC full-bridge inverter. Boostcontrol circuit consists of a PWM control chip SG3525and its peripheral circuits.While inverter control circuit consists of the unipolar SPWM wave generating circuit,a driving circuit and external protection circuit. After the hardware design, thesoftware designs are completed. Such as the system main program, A/D samplingprogram and the program of SPWM generated by the sine table.In this paper, a simulation model of inverter is established with the tool of Matlab/Simulink. It is showed in the simulation results that the output waveform ofthis system has the advantages of smooth sinusoidal, low total harmonic distortionrate, perfect load capacity and high dynamic response. This design is verified to becorrect and it provides technical support for the production of prototype.