Figure 1.
Schematic of PSFB converter with CD SR. CD, current-doubler; PSFB, phase-shift full-bridge; SR, synchronous rectifier.
Table 1.
Parameters of the PSFB with CD rectifier.
| Parameter | Value |
|---|---|
| Input voltage (VIN) | 390 V |
| Output voltage (VOUT) | 24 V |
| Output current (IOUT) | 25 A |
| Frequency (f) | 500 kHz |
| Transformer ratio (p) | 6 |
| Leakage inductance (Lk) | 3.5 μH |
| Filter inductance (L1 and L2) | 22 μH |
| Output capacitance (COUT) | 15 μF |
Figure 2.
Simulation waveform of overvoltage occurrence on TSR1.
Table 2.
Parameters of selected transistors.
| IPTG014-N10NM5 | IPTG025-N15NM6 | EPC2302 | EPC2305 | |
|---|---|---|---|---|
| Technology | Si | Si | GaN HEMT | GaN HEMT |
| Manuf. | Infineon | Infineon | EPC | EPC |
| VDS (V) | 100 | 150 | 100 | 150 |
| ID (A) | 366 | 264 | 133 | 133 |
| RDson (mΩ) | 1.4 | 2.5 | 1.8 | 2.2 |
| Qoss (nC) | 214 | 310 | 85 | 103 |
| Qg (nC) | 169 | 105 | 23 | 22 |
| RDson Qoss | 299.6 | 775 | 153 | 226.6 |
| RDson Qq | 236.6 | 262.5 | 41.4 | 48.4 |
| Footprint area (mm2) | 120 | 120 | 15 | 15 |
Figure 3.
Calculated losses of SR transistors. SR, synchronous rectifier.
Table 3.
Transistors losses at 100% load.
| IPTG014-N10NM5 | IPTG025-N15NM6 | EPC2302 | EPC2305 | |
|---|---|---|---|---|
| Pcon (W) | 0.22 | 0.39 | 0.28 | 0.34 |
| Poss (W) | 3.38 | 4.89 | 1.34 | 1.63 |
| Pgate (W) | 1.27 | 0.79 | 0.17 | 0.17 |
| Ptotal (W) | 4.86 | 6.07 | 1.79 | 2.13 |
Figure 4.
Simulated losses of EPC GaN transistors in PLECS. GaN, gallium nitride.
Figure 5.
Difference between SR switching in DCM and CCM obtained from PLECS simulation for transistor TSR1. CCM, continuous conduction mode; DCM, discontinuous conduction mode; SR, synchronous rectifier.
Figure 6.
Possible range of delay for mode 2 in CCM. CCM, continuous conduction mode.
Figure 7.
Schematic of PSFB converter with SR and AC. AC, active clamp; PSFB, peak current mode control; SR, synchronous rectifier.
Figure 8.
Schematic of PSFB converter with SR and AC. AC, active clamp; PSFB, peak current mode control; SR, synchronous rectifier.
Figure 9.
Laboratory set-up. AC, active clamp; DSP, digital signal processor.
Table 4.
Parameters of the laboratory model of the PSFB Converter.
| Parameter | Value |
|---|---|
| Input voltage (VIN) | 390 V (reduced to 195 V during measurements) |
| Output voltage (VOUT) | 24 V |
| Output current (IOUT) | 25 A |
| Frequency (f) | 500 kHz |
| Transformer ratio (p) | 6 |
| Leakage inductance (Lk) | 3.5 μH |
| Magnetising inductance | 726.9 μH |
| Filter inductance (L1 and L2) | 22 μH |
| Output capacitance (COUT) | 15 μF |
| Inverter transistors (T1–T4) | GS-065-011 |
| SR transistors (TSR1, TSR2) | EPC 2305 |
| AC transistors (TAC1, TAC2) | ISC046N13NM6ATMA1 |
| AC capacitance (CAC1, CAC2) | 2 μF |
Figure 10.
Waveform of vP, iP, vds TSR1 and vo, at half load 12.5 A and half input voltage (400 ns/div, CH1: 250 V/div, CH2: 2 A/div, CH3: 20 V/div, CH4: 5 V/div).
Figure 11.
Waveform of vp, ip, vds TSR1 and vgs TSR1, difference in SR transistor switching between DCM and CCM, at quarter input voltage (400 ns/div, CH1: 100 V/div, CH2: 2 A/div, CH3: 20 V/div, CH4: 10 V/div). CCM, continuous conduction mode; DCM, discontinuous conduction mode; SR, synchronous rectifier.
Figure 12.
Efficiency of the laboratory model at half of input voltage.
Figure 13.
Thermal image of the driver of GaN transistors in a rectifier. GaN, gallium nitride.