同步整流原理.doc

SR(同步整流)circuit 動作原理一、正常時之動作原理+ -+ -於滿載時：當Q050 OFF，Q204 OFF，Q206 ON，D203導通，Q203 ON，電流得以流經R203使Q200 ON。當Q050 ON, L200產生反偏壓, 電流方向相反, 使得Q204 ON, 將Q200之Vds接至等電位，因此Q200無法導通, 成OFF狀態。於輕載時：當Q050 OFF，Q204 OFF，但Q206 Vds電壓不足以將Q206 ON，因此D203 OFF，Q203 OFF，電流無法流過，使Q200 OFF。二、當ZD200 short之動作原理於滿載時：當Q050 OFF，Q204 OFF，Q206 ON，D203導通，Q203 ON，電流得以流經R203使Q200 ON。當Q050 ON，原本Q204必須ON，將Q200 OFF，但由於ZD204零件short，使得Q204無法ON，造成Q200依然 ON。整個控制線路不正常，原本的工作頻率70KHz也變成16KHz。Test Conditions = PSU is working normallyInput Voltage = 220V/50Hz(CH1)Q050 Voltage = 642V(CH2)Q050 Current =1.305ATest Conditions = Open R053Input Voltage = 220V/50Hz(CH1)Q050 Voltage = 677.5V(CH2)Q050 Current =1.317ATest Conditions = PSU is working normallyInput Voltage = 220V/50Hz(CH1)Q050 Voltage = 642V(CH2)Q050 Current =1.305ATest Conditions = Short ZD200Input Voltage = 220V/50Hz(CH1)Q050 Voltage = 579.6V(CH2)Q050 Current =1.132ATest Conditions = PSU is working normallyInput Voltage = 220V/50Hz(CH1)Q050 Voltage = 642V(CH2)Q050 Current =1.305ATest Conditions =Open R053 and Short ZD200Input Voltage = 220V/50Hz(CH1)Q050 Voltage = 584.0V(CH2)Q050 Current =1.235ATest Conditions = PSU is working normallyInput Voltage = 220V/50Hz(CH1)Q200 Voltage = 96.5V(CH2)Q200 Current =2.253ATest Conditions = Open R053 Input Voltage = 220V/50Hz(CH1)Q200 Voltage = 96.34V(CH2)Q200 Current =2.256ATest Conditions = PSU is working normallyInput Voltage = 220V/50Hz(CH1)Q200 Voltage = 96.5V(CH2)Q200 Current =2.253ATest Conditions = Short ZD200Input Voltage = 220V/50Hz(CH1)Q200 Voltage = 78.84V(CH2)Q200 Current =4.047ATest Conditions = PSU is working normallyInput Voltage = 220V/50Hz(CH1)Q200 Voltage = 96.5V(CH2)Q200 Current =2.253ATest Conditions = Open R053 and Sh