抄録
In PWM inverters, dead-time is necessary to prevent short-circuits in the power supply; the dead-time results in output quality deviations and hinders dc-link voltage utilization. In this paper, the dead-time mechanism of inverters with an LC filter is analyzed, and a mathematical model is presented. Using this model, we propose a new current control scheme involving the use of a PI controller and a sliding mode controller. Depending on the sliding mode controller output, the upper side switch or the lower side switch can be kept off, and the counter side switch can be controlled up to a PWM duty of 100%, with a smooth transition between different dead-time operation modes. The scheme maximizes the dc-link voltage utilization and improves the conversion efficiency. Experimental results show that harmonic distortion is decreased to 1/3-1/2 of that in the conventional PI control scheme, the dc-link voltage can be reduced by about 10%, and an improvement of 1.6% is achieved in the efficiency.
