Publication: Development of 1 kw inverter using microcontroller
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Date
2010-04-01
Authors
Lee, Sze Sing
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Abstract
This thesis shows the design and implementation of microcontroller-based single phase full bridge inverter. The input voltage is 12VDC while the output is 240VAC with frequency of 50Hz. The inverter has been divided into two parts; switching circuit and single phase full bridge inverter. The complete circuit design is simulated using PSIM and PROTEUS software to make sure the design is theoretically achieved high performance. The switching technique used is SPWM switching technique incorporating PIC microcontroller. The PIC microcontroller is programmed to directly generate SPWM switching signals for the inverter. Prior to the PIC programming, a MATLAB program is run to calculate the SPWM switching angles. The switching circuit is implemented by using two half bridge MOSFET drivers incorporating bootstrap operation. Bootstrap operation enable switching circuit to trigger the high side and low side MOSFETs simultaneously by sending the SPWM switching signal to the MOSFETs. Designed circuit is assembled temporary on breadboard then shifted to printed circuit board for permanent assembly. It is tested with resistive load for output verification. The SPWM output voltage from full bridge inverter is stepped up by using a transformer to 240Vrms and filtered with a LC low pass filter to achieve sinusoidal waveform. The THD output voltage is 3.8% while output current is 3.2% for a resistive load of 400Ω. Measured output is compared with the simulated output to determine the performance of designed microcontroller-based single phase full bridge inverter.