60W Flyback CCM design
Input:
输入电压范围: 85Vac~265Vac
正常输入电压: Vin=220Vac
输入频率范围: 47Hz~63Hz
Normal input frequency: 50Hz
Output:
输出: Vo=12V Io=5A
Other:
开关频率: Fs=100Khz
Output diode forward voltage: Vf=1V
Effiency: Eff≥75%
Maximum cycle duty: Dmax=0.48
Delta B value: delta B=0.22T
Reflection voltage: Vor=110V
Line regulation ratio: a=±0.5%
Load regulation ratio: b=±0.5%
Output power: Po=(Vo+Vf)*Io=1=13V*5A=65W
Input power: Pin=Po/eff=65W/0.75=86.667W
Minimum bus input voltage: Vbusmin=1.414*Vinmin-20Vdc=1.414*85V-20V=100.208V
Maximum primary current: Ipmax=Pin/Vbusmin=86.667W/100.208V=0.865A
Primary CCM low peak current: Ippk2=Ipmax/2*Dmax=0.865A/2*0.48=0.901A
Primary CCM high peak current: Ippk1=3Ippk2=3*0.901=2.703A
Primary induction: Lp=Vbusmin*Dmax/(Fs*(Ippk1-Ippk2))=267uH
Choose Core: AP=[(Lp*Ipmax^2*10^4)/(450*Bmax*Ko)]^1.143=457mm^4
计算到这边,就是要开始选core了,根据AP来选的话,EFD15的AP为470mm^4
然而看了一份core的datasheet发现EFD15做不了60W的功率,那么应该如何选择这个core呢?