A Carrier-Based Discontinuous PWM for an 80 Kw PV Inverter With the Reduction of the DC-Link Voltage Ripple and Common Mode Current
Zhaoxia Yang, Jianwu Zeng, Qixing Ren, Liangcai Wu, Qun Zhang
Abstract
Discontinuous pulsewidth modulation (DPWM) method is broadly used in three-phase inverter to achieve high efficiency through the reduction of the switching loss. The high-power rating photovoltaic (PV) inverter with DPWM has its intrinsic issues such as large dc-link voltage ripple and high-frequency resonant current due to the large stray capacitance proportional to the power rating. To extend the application of DPWM from 10 kW to 80 kW PV inverter, a new DPWM method (DPWMn), which divides the clamping period into <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> intervals is proposed to achieve the three objectives simultaneously: 1) reduction of the dc-link voltage ripple; 2) suppression of the high-frequency current oscillation; 3) improve the efficiency compared to the continuous space vector PWM (SVPWM). The proposed DPWMn is validated by an 80 kW three-phase T-type PV inverter. Compared to the SVPWM, the DPWMn has reduced 30% switching loss while maintaining the similar power quality and the common mode current. Compared to the existing DPWM methods, DPWMn reduces the voltage ripple by 52% and has the minimum energy ripples. Furthermore, the carrier-based DPWMn only utilizes the measured voltage and can be easily implemented.