K.Sharmila Sowjanya, Sri. M. Gopichand Naik, J.V.G. Rama Rao
Abstract: Single Phase induction motors are widely accepted motor due to their energy efficient characteristics. To drive varying mechanical loads for long duty, the machine needs to be controlled to increase its efficiency and minimize harmonics. This paper presents the voltage control method using semiconductor power devices for a single-phase induction motor in order to achieve a smooth, continuous and low total harmonics distortion (THD) waveforms. This paper implements a new single-phase nine-level inverter fed with photovoltaic systems, with a pulse width-modulated (PWM) control scheme which is used to generate the PWM signals for the inverter. This multilevel inverter allows Maximum Power Point Tracking (MPPT) to extract maximum power from the sun when it is available. An adaptive MPPT algorithm is used with a standard perturb and observe method for the PV system. A boost converter is used to step up the input voltage of the inverter interposed between the PV array and Nine-Level Inverter. This new nine-level inverter with reduced number of switches converts DC to AC which is capable of producing nine levels of output-voltage levels (Vdc, 3Vdc/4, Vdc/2, Vdc/4, 0, -Vdc/4, -Vdc/2, -3Vdc/4, - Vdc) from the dc supply voltage. The Pulse Width Modulation (PWM) signals are generated to the inverter by using PID and Fuzzy Controllers and the total harmonic distortion (THD) results are compared. The LC-filter is modeled to obtain pure sine-wave and is given to drive a single-phase induction motor. The voltage control of Single-Phase Induction Motor for better performance is modeled and implemented in MATLAB / SIMULINK environment. The Simulation circuit is analyzed and results are presented for the system.
Keywords: multilevel inverter, photovoltaic PV system, pulse width-modulated PWM, total harmonic distortion THD MPPT