Cascaded Inverters Increasing the Number of Levels and Effective Switching Frequency in Output Using Coupled Inductors

In this article, a new coupled-inductor-based modular multilevel cascaded inverter using a new phase shift control is presented. The proposed inverter can generate a high output ac voltage using standard low-voltage-rating devices. The number of levels in the output pulsewidth modulation (PWM) voltage and the effective switching frequency of the output filter are increased using coupled inductors and phase shift control. The switching signals of the cascaded units in the proposed inverter are phase-shifted by
${\mathbf {360}}{\mathbf {^{\circ }}}{/4n}$
, where
${n}$
is the number of cascaded units. The proposed phase shift control results in (
$4{n}$
+ 1) levels in the output PWM voltage of the proposed inverter and increases the effective switching frequency of the output filter by 4n times the actual switching frequency
${f}_{\mathbf {sw}}$
. As a result, the output waveforms can be generated with better quality and less distortion. In addition, the output filter can be decreased dramatically in size. Besides, fewer coupled inductors are used to reduce the footprints, the number of inductors, and magnetic volume. Moreover, the proposed inverter is exceptionally reliable due to no short-circuit risk in the circuit.