# Bridgeless Buck-Boost PFC Rectifier with Positive Output Voltage
## 5 Experimental Results  
Prior to this section, an input filter with corner frequency of about 10 kHz, constructed by one inductor of 500 \(\mu\)H and one capacitor of 470 nF, is put between the input voltage and the circuit, so as to remove high-frequency component of the input current. Figures 4-8 are measured at the rated output power and the input voltage of 110 V\({}_{\text{rms}}\). Figure 4 displays the input voltage \(v_{in}\) and the input current \(i_{in}\). From Figure 4, it can be seen that the input current \(i_{in}\) tracks the input voltage \(v_{in}\) as tightly as possible, so as to realize power factor correction. Figure 5 shows the input current harmonic distribution, which meets IEC61000-3-2 Class C. Under the positive input voltage, Figure 6a displays the PWM signal for both \(S_{1}\) and \(S_{2}\), named \(v_{gs1,2}\), and the voltages across the switches \(S_{1}\) and \(S_{2}\), named \(v_{ds1}\) and \(v_{ds2}\), whereas under the negative input voltage, Figure 6b shows the PWM signal for both \(S_{1}\) and \(S_{2}\), named \(v_{gs1,2}\), and the voltages across the switches \(S_{1}\) and \(S_{2}\), named \(v_{ds1}\) and \(v_{ds2}\). From Figure 6a,b, as the switch \(S_{1}\) or \(S_{2}\) is turned off, the voltage across \(S_{1}\) or \(S_{2}\) is about 180 V. Note that under the positive cycle, as the PWM signal is low, the voltage across \(S_{1}\) is high but the voltage across \(S_{2}\) is zero due to forward bias of the body diode of \(S_{2}\), whereas under the negative cycle, as the PWM signal is low, the voltage across \(S_{2}\) is high but voltage across \(S_{1}\) is zero due to forward bias of the body diode of \(S_{1}\). Figure 7a displays the PWM signal \(v_{gs3}\), and the voltage across the switch \(S_{3}\). From Figure 7a, as the switch \(S_{3}\) is turned off, the voltage across \(S_{3}\) is about 80 V. Figure 7b shows the PWM signal for both \(S_{1}\) and \(S_{2}\), named \(v_{gs1,2}\), and the current in \(L_{1}\), named \(i_{L}\), whereas Figure 8 displays the low-frequency output voltage ripple \(\overline{v}_{o}\). From Figure 7b, it can be seen that the inductor works in the DCM, whereas from Figure 8, it can be seen that the peak-to-peak value of \(\overline{v}_{o}\) is about 2.4 V, close to (22).  
Figure 4: Experimental waveforms at rated output power under 110 V\({}_{\text{rms}}\) input voltage: (1) \(v_{in}\); (2) \(i_{in}\).  
Figure 5: Experimental harmonics distribution at rated output power under 110 V\({}_{\text{rms}}\) input voltage.  
Figure 6: Experimental waveforms at rated output power under: (**a**) the peak value of the positive cycle of 110 V\({}_{\text{rms}}\) input voltage: (1) \(v_{gs1,2}\); (2) \(v_{ds1}\); (3) \(v_{ds2}\); (**b**) the valley value of the negative cycle of 110 V\({}_{\text{rms}}\) input voltage: (1) \(v_{gs1,2}\); (2) \(v_{ds1}\); (3) \(v_{ds2}\).  
Figure 14: Experimental waveforms at rated output power under 130 V\({}_{\text{rms}}\) input voltage: (1) \(v_{in}\); (2) \(i_{in}\).  
Figure 12: Experimental waveforms at rated output power under 90 V\({}_{\text{rms}}\) input voltage: (a) (1) \(v_{gs3}\); (2) \(v_{ds3}\); (b) (1) \(v_{gs12}\); (2) \(i_{L}\).  
Figure 13: Experimental output voltage ripple \(\overline{v}_{o}\) at rated output power under 90 V\({}_{\text{rms}}\) input voltage.  
Figure 15: Experimental harmonics distribution at rated output power under 130 V\({}_{\text{rms}}\) input voltage.