EVL6563S-200ZRC STMicroelectronics, EVL6563S-200ZRC Datasheet - Page 11

• Manufacturer Part Number: EVL6563S-200ZRC
• Description: Power Management Modules & Development Tools Tranisition Mode PFC L6563S EVL Board
• Manufacturer: STMicroelectronics
• Type: Motor / Motion Controllers & Driversr

Specifications of EVL6563S-200ZRC

• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN3180
If the attenuation A is defined as the ratio of the residual ripple di
or
to the actual ripple on the cancellation winding, as L
the worst case scenario:
Equation 10
where Δv(t) = v
condition mismatch (absolute and relative values coincide) and the factor ρ is given by:
Equation 11
In
Δv(t)/v
the inspection of these plots, it is apparent that a low coupling coefficient is essential for a
good attenuation even if the zero-ripple condition is not exactly met. To achieve attenuations
always greater than 10-12 dB even with a tolerance of ±10 % on the value of δ and 10 %
voltage mismatch, the coupling coefficient k must be around 0.7. Lower k values would lead
to a higher insensitivity of the zero-ripple condition due to mismatches but lead to more
turns for the DC winding, which could become an issue in terms of inductor construction.
Note that in case of under-compensation (δ<0) the residual ripple can be higher than the
original value: this is due to a too low value of the “residual” inductance L
Extending these concepts to the smoothing transformer of
externally applied to the AC winding is affected by the voltage ripple on the capacitor C
(due to its finite capacitance value as well as its ESR), the voltage mismatch Δv(t)/v
as a result, also the attenuation A, become frequency-dependent. Magnetic flux distribution
modifications with frequency, which also affect δ, are a second-order effect and are
neglected.
References 1
behavior. Here it is convenient only to summarize the results:
1.
2.
3.
4.
Figure 7
8
, to the ripple that would be there without the coupled inductor (di
The smoothing transformer is capable of a third-order attenuation of current ripple, i.e.
it is equivalent to an inductor combined with an additional LC filter
The transfer function generally includes three poles and two zeros; if the zero-ripple
condition is fulfilled (δ=0), the two zeros go to infinity and the smoothing transformer
becomes a third-order all-pole filter
Modeling winding resistance and capacitor ESR produces a little damping of the pole-
zero resonances but do not significantly affect the imaginary component of their
locations
The effect of the zero-ripple condition mismatch (δ≠0) is to move the zero pair towards
the poles, therefore creating some “notch” frequencies where greater attenuation is
achieved, but degrading the overall attenuation produced at higher frequencies
1
(t) and of the coupling coefficient k, as a function of the zero-ripple condition. From
the attenuation A is plotted for different values of the relative voltage mismatch
and
2
(t)-v
2
provide a complete analysis of the smoothing transformer frequency
1
(t) is the absolute voltage mismatch, δ = k n
A
=
d
Doc ID 17273 Rev 1
d
i
i
dt
dt
1
2
) t (
) t (
=
ρ
v
=
L
1
) t (
1
(
1
+
d
1
δ
i
dt
2
Sensitivity of zero-ripple current condition
)
) t (
2
1
−
=
k
1
2
k
ρ
is unchanged), it is possible to write for
2
⎛
⎜
⎜
⎝
Δ
v
1
v(t)
) t (
Figure 3
+
δ
2
⎞
⎟
⎟
⎠
(t)/dt, given by
e
, where the voltage
- 1 is the zero-ripple
1
(t)/dt =v
2
(1-k
1
2
(t)/L
).
Equation 7
1
1
, equal
(t) and,
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