肯定是變壓器參數(shù)不合理

測一下變壓器的漏感有多大

把變壓器裝上樣機后,測一下開關(guān)頻率看是否穩(wěn)定

效率低，肯定是變壓器的設(shè)計不合理。同時，也就導(dǎo)致你所說的線徑選擇有問題。還有樓下提到的，測試漏感。

沒有看計算過程，建議如下：

1、開關(guān)頻率設(shè)置為50-100KHZ；

2、DMAX設(shè)置為0.5-0.6,；

3、LP設(shè)置為60-100UH（KRP設(shè)置在0.40-0.66左右）；

4、采用三明治繞法，初級平鋪2至4層，次級剛好平鋪1-2層。

      （不要擋墻，初次級均采用單根或者兩根線）

總之一句話，盡可能的增大LP，盡可能的改善變壓器耦合，祝你好運！

這是PI的電子數(shù)據(jù)表格，計算出的參數(shù)可以參考一下：

VACMIN 12   Volts Minimum AC Input Voltage
VACMAX 12   Volts Maximum AC Input Voltage
fL 50   Hertz AC Mains Frequency
VO 5.00   Volts Output Voltage (main)
PO 10.00   Watts Output Power
n 0.80    Efficiency Estimate
Z 0.50    Loss Allocation Factor
VB 12   Volts Bias Voltage
tC 3.00   mSeconds Bridge Rectifier Conduction Time Estimate
CIN 1200.00   uFarads Input Filter Capacitor
     
ENTER TOPSWITCH-GX VARIABLES     
TOP-GX TOP247   Universal 115 Doubled/230V
Chosen Device  TOP247 Power Out 125W 165W
KI 1.00    External Ilimit reduction factor (KI=1.0 for default ILIMIT, KI <1.0 for lower ILIMIT)
ILIMITMIN   3.348 Amps Use 1% resistor in setting external ILIMIT
ILIMITMAX   3.852 Amps Use 1% resistor in setting external ILIMIT
Frequency (F)=132kHz, (H)=66kHz h    Half (H) frequency option - 66kHz
fS   66000 Hertz TOPSwitch-GX Switching Frequency: Choose between 132 kHz and 66 kHz
fSmin   61500 Hertz TOPSwitch-GX Minimum Switching Frequency
fSmax   70500 Hertz TOPSwitch-GX Maximum Switching Frequency
VOR 12.00   Volts Reflected Output Voltage
VDS 0.00   Volts TOPSwitch on-state Drain to Source Voltage
VD 0.45   Volts Output  Winding Diode Forward Voltage Drop
VDB 0.50   Volts Bias Winding Diode Forward Voltage Drop
KP 0.40    Ripple to Peak Current Ratio (0.4 < KRP <  1.0 : 1.0< KDP<6.0)
     
ENTER TRANSFORMER CORE/CONSTRUCTION VARIABLES     
Core Type EE16    
Core  EE16  P/N: PC40EE16-Z
Bobbin  EE16_BOBBIN  P/N: BE-16-118CPH
AE   0.192 cm^2 Core Effective Cross Sectional Area
LE   3.5 cm Core Effective Path Length
AL   1140 nH/T^2 Ungapped Core Effective Inductance
BW   8.6 mm Bobbin Physical Winding Width
M 0.00   mm Safety Margin Width (Half the Primary to Secondary Creepage Distance)
L 2.00    Number of Primary Layers
NS 20     Number of Secondary Turns
     
DC INPUT VOLTAGE PARAMETERS     
VMIN   12 Volts Minimum DC Input Voltage
VMAX   17 Volts Maximum DC Input Voltage
     
CURRENT WAVEFORM SHAPE PARAMETERS     
DMAX   0.50  Maximum Duty Cycle
IAVG   1.05 Amps Average Primary Current
IP   2.61 Amps Peak Primary Current
IR   1.05 Amps Primary Ripple Current
IRMS   1.50 Amps Primary RMS Current
     
TRANSFORMER PRIMARY DESIGN  PARAMETERS     
LP   84 uHenries Primary Inductance
NP   44  Primary Winding Number of Turns
NB   46  Bias Winding Number of Turns
ALG   43 nH/T^2 Gapped Core Effective Inductance
BM   2588 Gauss Maximum Flux Density at PO, VMIN (BM<3000)
BP   3816 Gauss Peak Flux Density (BP<4200)
BAC   518 Gauss AC Flux Density for Core Loss Curves (0.5 X Peak to Peak)
ur   1654  Relative Permeability of Ungapped Core
LG   0.54 mm Gap Length (Lg > 0.1 mm)
BWE   17.2 mm Effective Bobbin Width
OD 0.60  0.60 mm Maximum Primary Wire Diameter including insulation
INS   0.07 mm Estimated Total Insulation Thickness (= 2 * film thickness)
DIA   0.53 mm Bare conductor diameter
AWG   24 AWG Primary Wire Gauge (Rounded to next smaller standard AWG value)
CM   406 Cmils Bare conductor effective area in circular mils
CMA   272 Cmils/Amp Primary Winding Current Capacity (200 < CMA <  500)
     
TRANSFORMER SECONDARY DESIGN PARAMETERS (SINGLE OUTPUT EQUIVALENT)     
Lumped parameters     
ISP   5.75 Amps Peak Secondary Current
ISRMS   3.28 Amps Secondary RMS Current
IO   2.00 Amps Power Supply Output Current
IRIPPLE   2.60 Amps Output Capacitor RMS Ripple Current
     
CMS   656 Cmils Secondary Bare Conductor minimum circular mils
AWGS   21 AWG Secondary Wire Gauge (Rounded up to next larger standard AWG value)
DIAS   0.73 mm Secondary Minimum Bare Conductor Diameter
ODS   0.43 mm Secondary Maximum Outside Diameter for Triple Insulated Wire
INSS   -0.15 mm Maximum Secondary Insulation Wall Thickness
     
VOLTAGE STRESS PARAMETERS     
VDRAIN   62 Volts Maximum Drain Voltage Estimate (Includes Effect of Leakage Inductance)
PIVS   13 Volts Output Rectifier Maximum Peak Inverse Voltage
PIVB   30 Volts Bias Rectifier Maximum Peak Inverse Voltage
     
     
     
     
     
TRANSFORMER SECONDARY DESIGN PARAMETERS (MULTIPLE OUTPUTS)     
1st output     
VO1   5 Volts Output Voltage
IO1   2.00 Amps Output DC Current
PO1   10.00 Watts Output Power
VD1   0.45 Volts Output Diode Forward Voltage Drop
NS1   20.00  Output Winding Number of Turns
ISRMS1   3.282 Amps Output Winding RMS Current
IRIPPLE1   2.60 Amps Output Capacitor RMS Ripple Current
PIVS1   13 Volts Output Rectifier Maximum Peak Inverse Voltage
     
CMS1   656 Cmils Output Winding Bare Conductor minimum circular mils
AWGS1   21 AWG Wire Gauge (Rounded up to next larger standard AWG value)
DIAS1   0.73 mm Minimum Bare Conductor Diameter
ODS1   0.43 mm Maximum Outside Diameter for Triple Insulated Wire
     
2nd output     
VO2    Volts Output Voltage
IO2    Amps Output DC Current
PO2   0.00 Watts Output Power
VD2   0.7 Volts Output Diode Forward Voltage Drop
NS2   2.57  Output Winding Number of Turns
ISRMS2   0.000 Amps Output Winding RMS Current
IRIPPLE2   0.00 Amps Output Capacitor RMS Ripple Current
PIVS2   1 Volts Output Rectifier Maximum Peak Inverse Voltage
     
CMS2   0 Cmils Output Winding Bare Conductor minimum circular mils
AWGS2   N/A AWG Wire Gauge (Rounded up to next larger standard AWG value)
DIAS2   N/A mm Minimum Bare Conductor Diameter
ODS2   N/A mm Maximum Outside Diameter for Triple Insulated Wire
     
3rd output     
VO3    Volts Output Voltage
IO3    Amps Output DC Current
PO3   0.00 Watts Output Power
VD3   0.7 Volts Output Diode Forward Voltage Drop
NS3   2.57  Output Winding Number of Turns
ISRMS3   0.000 Amps Output Winding RMS Current
IRIPPLE3   0.00 Amps Output Capacitor RMS Ripple Current
PIVS3   1 Volts Output Rectifier Maximum Peak Inverse Voltage
     
CMS3   0 Cmils Output Winding Bare Conductor minimum circular mils
AWGS3   N/A AWG Wire Gauge (Rounded up to next larger standard AWG value)
DIAS3   N/A mm Minimum Bare Conductor Diameter
ODS3   N/A mm Maximum Outside Diameter for Triple Insulated Wire
     
Total power   10 Watts Total Power for Multi-output section
     
Negative Output 3  3  Output # 3 is negative output

只有12V輸入，開關(guān)頻率選240KHZ，一點也不過分；

現(xiàn)在的關(guān)鍵問題是LP太小了，變壓器耦合可能不好，分布參數(shù)影響嚴重。

我的參數(shù)并不嚴謹，給出的只是一種解決思路。

我現(xiàn)在也有一款20V輸入的，反激QR模式，LP只有40幾UH（20多瓦）。