Dead time effect on the double loop control strategy for a boost inverter

The boost inverter topology achieves both boosting and inversion in a single stage. Various controllers have been implemented on boost inverters to obtain stable operation. However, the double loop control strategy is the most appropriate because it provides good performance under nonlinear loads, abrupt load variations and transient short-circuit conditions. The double loop control strategy was introduced with proportional integral (PI) controllers used in each loop. Recently, with the widespread use of proportional resonant (PR) controllers, the PI controllers were replaced with the PR controllers to achieve zero steady state error for the ac components of the reference. However, during the implementation of the PR controllers, a significant dc offset in the output voltage of the boost inverter was observed. Furthermore, the output voltages of the boost converters showed a clipping effect. In this paper, it is shown that the dc offset and the clipping of the boost converters are attributed to the dead time and parameter mismatch between the boost converters. A new controller is proposed to reduce the dc offset and clipping effect. The improved performance of the proposed controller is demonstrated with experimental results on a boost inverter prototype.