FA5695 Datasheet, PDF (12/21 Pages) Fuji Electric – Fuji Switching Power Supply Control IC

FA5695
(2) Power-factor correction operation
As explained in the switching operation, the
current flowing through the inductor repeats in
triangular waveforms. The mean value (IL 1(mean))
of the triangular wave current becomes 1/2 of the
peak value (IL 1(peak)). (Fig. 3)
By controlling to make outline linking the peak of
the inductor current to sine wave and removing
switching ripple current, the smoothed current
flowing from the AC input power source has sine
wave shape.
IL1(peak)
IL1
IL1(mean)
=1/2×IL1(peak)
FA5590/FA5591 uses fixed on time control
shown in Fig. 4.
This control determines the on time of the output
of IC (gate drive signal for Power Mos) with
combination of the error amplifier output and saw
tooth wave. While the load is constant, the output
of the error amplifier is constant, and on time also
stays constant.
Since an inclination of inductor current depends on
input voltage (an inclination of inductor current is
proportional to input voltage) and on time is
constant, the outline linking the peak of the inductor
current becomes same AC waveform as the input
voltage, which enables power-factor correction
operation.
拡en大larged
2×Iin(peak)
IL1
inpu_入t _力vo_電lta_圧ge
C_fil1_tで_erス_edイ_tッ_heチ_hン_igグ_h に
伴うリップル
frequency content
電流を除去
by C1
e_エr_ラro_ーr _アam_ンプplifier
出o力utput
Iin
Iin(peak)
MOSFET
Fig.3 Outline of inductor and AC input current
Gate
inductor
イン^cダ^urク^reタⁿ電^t 流
While the output of the error
エラーアンプの出力が一定
(è² ^am荷^p一^lif定^ie)^rの^iså ´^c合^o、ⁿオ^stン^an幅^tが^{and load is}
一co定nとstなanるt(,オoンn幅ti固m定e 制sta御y)s constant
(Fixed on time control)
Outline linking the peak
インダクタ電流
of t_ピh_ーe_クinductor current _{入力電流のピークが入力}
電圧と同じAC波形となる
(力率改善動作)
インaダvクeタr電ag流e waveform of
th^平e^均inductor current
インダクタ電流ゼロのタイミングで
when the i_Pn_od_wu_ec_rt_Mo_or_sc_がu_オrre_ンn_しt_、g_のo_こes_ぎd_りo_波w_がn
to zero, Power M立OちS上がtuるrn(臨s o界n動a作nd) saw
tooth wave starts to rise
Outline linking the peak of the inductor
current has the same waveform of the
input voltage
(Power factor correction operation)
Fig.4 Fixed on time control
Fuji Electric Co., Ltd.
AN-073E Rev.1.1
April-2011
http://www.fujielectric.co.jp/products/semiconductor/
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