Cascaded Hybrid Five-level Inverter with Dual Carrier Pwm Control Scheme for Pv System

Cascaded Hybrid MultiLevel Inverter (CHMLI) is an attractive topology for high voltage DC-AC conversion. This paper focuses on a single-phase five-level inverter with reduced number of switches. The inverter consists of a full bridge inverter and an auxiliary circuit with four diodes and a switch. The inverter produces output voltage in five levels: zero, +0.5Vdc, +Vdc, -0.5Vdc and –Vdc.. A novel dual reference modulation technique has been proposed for the CMLI. The dual carrier modulation technique uses two identical inverted sine carrier signals each with amplitude exactly half of the amplitude of the sinusoidal reference signal to generate PWM signals for the switches. Using Perturb and Observe (P&O) algorithm, Maximum Power Point (MPPT) has been tracked for PV inverter. A Proportional Integral (PI) control algorithm is implemented to improve the dynamic response of the inverter. Performance evaluation of the proposed PWM strategy for Multilevel Inverter (MLI) has been carried out using MATLAB and it is observed that it gives reduced Total Harmonic Distortion (THD). An experimental five-level hybrid inverter test rig has been built to implement the proposed algorithm. Gating signals are generated using PIC microcontroller. The performance of the inverter has been analyzed and compared with the result obtained from theory and simulation.