LOW-THD 110 V RMS, 60 HZ PROPORTIONAL-INTEGRAL REGULATED SINGLE-PHASE FULL-BRIDGE INVERTER WITH 10 KHZ SPWM AND LC FILTERING

Abstract

The single-phase full-bridge inverter topology here shown illustrates a robust and efficient means of DC input to a stable 110 V RMS AC output at 60 Hz. Sinusoidal pulse-width modulation (SPWM) with a high-frequency triangular carrier signal (10 kHz) allows for precise control of the four IGBT switches, and thus, the generation of a high-quality AC waveform. The use of an LC low-pass filter (L = 4.06 mH, C = 6.23 µF) further improves the output by filtering out the high-frequency components, thus contributing to the significantly low total harmonic distortion (THD) observed in voltage (--0.22%) and current. A closed-loop control system consisting of a bandwidth-high PI controller (Kₚ = 21, Kᵢ = 0.03155) is tasked with maintaining the stability and quality of the output. Through constant comparison of the filtered output with a 60 Hz reference signal, this controller adjusts the PWM duty cycle dynamically to compensate for variations in load or DC-bus voltage. Such adaptive control allows the inverter to maintain its target output within ±2% of the nominal value, even under severe load transients (±50%) and disturbances in the DC-bus. The fast recovery time, within a fraction of a cycle, is reflective of the system's marvelous dynamic response. Such performance attributes make the inverter design ideal for high-quality, stable AC power sourcing applications, such as renewable energy systems and uninterruptible power supplies (UPS).