4 Simulation

Figure 4-1 shows the SIMPLIS schematic of the single-phase PFC with the Y-capacitor charge distribution circuit. In this simulation, V1 is the AC source running at 230V_AC with a frequency of 50 Hz. In line with the switching functionality described in Figure 1-1, Q1 and Q2 switch at 100 kHz, Q3 and Q4 switch at 50 Hz, while Q5 and Q6 control the current source. The Y-capacitors are connected at the input ({C6} and {C8}) and at the output ({C7} and {C9}).

Figure 4-1. SIMPLIS Simulation of Single-Phase PFC with Y-Capacitor Charge Distribution Circuit

To illustrate how the Y-capacitance of the AC source influences the Common-mode current, C_Y-PFC was changed from 5 nF to 25 nF in increments of 5 nF in a multi-step test, while keeping C_Y-LOAD constant at 25 nF. This demonstrates the change in slope as the capacitor value changes, as shown in Figure 4-2.

Figure 4-2. Changing Slope in the Neutral Voltage with Changing Capacitor Value

To change the amount of current drawn from the current source circuit, the values of resistors R9 and R10 can be varied. When R9 is equal to R10, the positive and negative rates of charge of V (N, PGND) are the same. As the value of one resistor becomes greater than the other, the rate of charge becomes much steeper. Figure 4-3 depicts this behavior when the value of R9 is incremented from 20 ohms to 100 ohms, while keeping R10 constant at 20 ohms during the multi-step run in the simulation.

Figure 4-3. Changing Resistor to Change the Current Sourced to the Y-Capacitors