ripple current
5.For APFC with the determinations of the structure, power stage circuit, current modes, control methods and control IC, it can be shown that this traditional APFC has the following disadvantages, i.e. the greater ripple of output voltage, the longer response time of voltage loop and a great deal of switch ripple lying on the input current.
7.A new nonlinear current control technique is proposed,which is called “parabola PWM” method here,in which the current ripple is compared with a parabolic wave with reset to make the actual current track the reference current continually each cycle,and maintain the switching frequency to be nearly constant for a voltage-fed PWM converter.
8.It cna supply stable,continuous current with ripple factor less than 4%and work stably for along time without any forms of filters and current limiting resistance in the high voltage end even ifconnected a single- phase network service. The change of working current is less than±0.1mA,Thepresent power supply has the electrical transforming efficiency as high as 90%.
