METHOD FOR INTERLEAVING BETWEEN RECTIFIER AND INVERTER FOR NEUTRAL HARMONIC CURRENT REDUCTION OF UPS

The present invention relates to an interleaving method of an inverter and a rectifier for reducing a neutral line harmonic current of an uninterruptible power supply. The interleaving method of the present invention includes: (a) a process in which a signal processing part for a rectification part sets a GPIO pin as an output, and a signal processing part for the inverter sets a GPIO pin as an input; (b) a process in which the signal processing part for the rectification part changes an output signal of the GPIO pin at the time when a value of a PWM counter for the rectification part becomes zero; (c) a process in which the signal processing part for the inverter detects the time when an input signal is changed from low to high using the GPIO pin; (d) a process in which the signal processing part for the inverter converts the value of the PWM counter for the inverter at the time when the value of the PWM counter for the inverter detected through the GPIO pin becomes zero, and checks a phase of a PWM signal for the inverter using the converted value of the PWM counter for the inverter; and (e) a process in which the signal processing part for the inverter determines whether to change an inverter switching frequency, by comparing the final value of the PWM counter for the inverter with a value having a phase difference of 180 degrees with a PWM signal of the rectification part.