POWER LOSS ANALYSIS
To analyze the presented converter efficiency, the power loss is divided
into four parts, including inductors loss, power switches loss, diodes
loss, capacitors loss. The parasitic parameters are defined as follows:rL 1, rLp ,
and rLs are the equivalent series resistance
(ESR) of the inductor L 1 and the windingLp and Ls , respectively;Pcv,L 1 andPcv,cp are the core losses per unit volume, andVe,L 1 andVe,cp are the core volumes of inductorL 1 and coupled-inductor, respectively;rds is the power switch’s on-resistance;ton is the summary of rise time and delay time
and toff is the summary of fall time and delay
time; VDx and rDx are the
diodes forward drop voltage and forward resistance of diodesDx (x =1, 2, 3),respectively; rCi is the ESR of the capacitorsCi (i = 1, 2, o ). The power loss
analysis in detail will be expressed as following.
Power Loss of Inductors
Inductors power loss is divided into winding loss and core loss. The
winding loss relies on the flowing current and ESR of winding, which can
be derived as
()
The core losses of inductor L 1 and coupled
inductor can be calculated as
()
From (69) and (70), the total loss of the inductors can be expressed as
()
Power Loss of Power
Switches
The power loss of power switches includes the conduction loss caused by
on-resistance, and the switching loss caused by the transition times
when the power switches are turning on and turning off.
The power switches’ conduction and switching losses of the power
switches can be calculated as (72) and (73).
()
()
Therefore, (74) gives the total loss of S 1 andS 2.
()
Power Loss of Diodes
The power loss of the diodes is mainly caused by the forward voltage
drops and resistance of diodes, which can be derive as
()
()
Therefore, the power loss of the diodes can be calculated as follows
()
Power Loss of Capacitors
Due to the power loss of capacitors is caused by the ESR of capacitor,
the power loss of the capacitors can be expressed.
()
Efficiency Calculation
The total losses can be calculated as
()
The efficiency calculation of the proposed converter can be calculated
as following.
()