TIDUFB1 December 2024
Figure 2-2 shows a simplified, single-phase diagram of the Vienna rectifier. To control this rectifier, the duty cycle is controlled to regulate the voltage vxiN directly. That is, if the software variable Duty is set to 1, vxiN becomes the highest voltage possible by never turning the Q1 and Q2 switches on and letting the inductor connect to the DC bus though the bridge diode. Similarly when Duty is set to 0, PWM is modulated such that Q1 and Q2 always conduct, making vxiN connect to the midpoint of the DC bus (which is zero), which creates the lowest possible voltage for the switching cycle.
Figure 2-3 shows the detailed PWM configuration.