SMPS CONTROL DEVICE FOR AC SMPS WHICH START AUTOMATICALLY ACCORDING TO SUNRISE FOR SOLAR INVERTER SYSTEM AND THE METHOD WHEREIN

摘要

The present invention discloses a device and a method of controlling an AC input switched mode power supply (SMPS) automatically started and stopped at sunrise and sunset in a photovoltaic inverter system. The device of controlling an AC input SMPS in a photovoltaic system including an inverter unit converting DC power acquired from a photovoltaic module into AC power comprises: an inverter control unit controlling an operation of the inverter unit; an SMPS unit supplying power to the inverter control unit, so that the inverter control unit is able to operate; a power control unit connected with an AC power system to supply power to the SMPS unit; and a startup control unit controlling an operation of the power control unit by using a DC voltage acquired from the photovoltaic module. The startup control unit sends a signal to the power control unit, so that power is supplied to the SMPS unit when a voltage equal to or greater than an SMPS startup threshold voltage is input, and it is determined to be the time of sunrise. The inverter control unit measures a DC voltage acquired from the photovoltaic module and sends a signal to the power control unit to block power supplied to the SMPS unit when the voltage equal to or lower than a threshold stoppage voltage is input, and it is determined to be the time of sunset. According to the present invention, a free-wheeling diode and a blocking relay are utilized, thereby enhancing stability of the device and preventing a hunting phenomenon, and it is possible to operate an SMPS unit in daytime, thereby efficiently operating a photovoltaic system.