The Operation mode of Proposed TCR snubber
The implicit leakage inductance of the three winding , Llkg1 , Llkg2 , and Llkg3 , and the magnetizing inductance Lm are presented in detail in Fig.4(a)-(f) corresponding to each operation mode. The theoretical waveforms are shown in Fig.5.
Mode I [t0 – t1]: Mode I begins when the power switch M1 is turned on. This LED driver is designed to operate in DCM. The Lm current is zeroinitially, and it increases linearly. Meanwhile, the snubber capacitor Csnis charged resonantly through Llkg3 and Dsn1.
Mode II [t1 – t2]: Mode II start when the snubber capacitor voltage vsnreaches the line vg. Then, Dsn2 is turned on, and the remaining energy of Llkg3 is delivered to the input capacitor, Cin to be recycled.
Mode III [t2 – t3]: After the Llkg3 energy is fully transferred, Dsn1 and Dsn2 are disconnected, and vsn retains the value of vg. The Lm current is continuously increased.
Mode IV [t3 – t4]: Mode IV starts when M1 is turned off. Because vsn is initially identical to vg, Dsn2 is connected at once, and the current path instantly changes from M1 to Csn and Dsn2. The current path is through Csn , Dsn2 , Llkg1 ,and Lm ; Csn is discharged , and the current of Lm becomes slightly higher. Given that Csn is much larger than the power switch output capacitance Coss , the ZVS operation of M1 is performed due to the slow rise of vd as shown in Fig.5.
Mode V [t4 – t5]: When Vd reaches Vg + (N1 + N2) VLED the secondary diode D0 turn on, and the energy stored in Lm is released to the output. The initial value of the Llkg1 current at the beginning of Mode V is the same value of the Lm current at the end of Mode IV. Accordingly, the Llkg1 energy is transferred to Csn. This energy is recycled during the next period. Given that Csn is much large than Coss, the voltage peaking is effectively reduced.
Mode VI [t5 – t6]: The Lm energy is continuously released to the load side. The snubber network is not during this time.
The Operation mode of Proposed TCR snubberThe implicit leakage inductance of the three winding , Llkg1 , Llkg2 , and Llkg3 , and the magnetizing inductance Lm are presented in detail in Fig.4(a)-(f) corresponding to each operation mode. The theoretical waveforms are shown in Fig.5.Mode I [t0 – t1]: Mode I begins when the power switch M1 is turned on. This LED driver is designed to operate in DCM. The Lm current is zeroinitially, and it increases linearly. Meanwhile, the snubber capacitor Csnis charged resonantly through Llkg3 and Dsn1. Mode II [t1 – t2]: Mode II start when the snubber capacitor voltage vsnreaches the line vg. Then, Dsn2 is turned on, and the remaining energy of Llkg3 is delivered to the input capacitor, Cin to be recycled. Mode III [t2 – t3]: After the Llkg3 energy is fully transferred, Dsn1 and Dsn2 are disconnected, and vsn retains the value of vg. The Lm current is continuously increased. Mode IV [t3 – t4]: Mode IV starts when M1 is turned off. Because vsn is initially identical to vg, Dsn2 is connected at once, and the current path instantly changes from M1 to Csn and Dsn2. The current path is through Csn , Dsn2 , Llkg1 ,and Lm ; Csn is discharged , and the current of Lm becomes slightly higher. Given that Csn is much larger than the power switch output capacitance Coss , the ZVS operation of M1 is performed due to the slow rise of vd as shown in Fig.5.Mode V [t4 – t5]: When Vd reaches Vg + (N1 + N2) VLED the secondary diode D0 turn on, and the energy stored in Lm is released to the output. The initial value of the Llkg1 current at the beginning of Mode V is the same value of the Lm current at the end of Mode IV. Accordingly, the Llkg1 energy is transferred to Csn. This energy is recycled during the next period. Given that Csn is much large than Coss, the voltage peaking is effectively reduced. Mode VI [t5 – t6]: The Lm energy is continuously released to the load side. The snubber network is not during this time.
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