EVAL-ADE7763ZEB Analog Devices Inc, EVAL-ADE7763ZEB Datasheet - Page 25

• Manufacturer Part Number: EVAL-ADE7763ZEB
• Description: BOARD EVALUATION FOR ADE7763
• Manufacturer: Analog Devices Inc

Specifications of EVAL-ADE7763ZEB

• Main Purpose: Power Management, Energy/Power Meter
• Utilized Ic / Part: ADE7763
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

ACTIVE POWER CALCULATION
Power is defined as the rate of energy flow from the source to
the load. It is defined as the product of the voltage and current
waveforms. The resulting waveform is called the instantaneous
power signal and is equal to the rate of energy flow at any given
time. The unit of power is the watt or joules/s. Equation 9 gives
an expression for the instantaneous power signal in an ac system.
where:
V is the rms voltage.
I is the rms current.
The average power over an integral number of line cycles (n) is
given by the expression in Equation 10.
where:
T is the line cycle period.
P is the active or real power.
Note that the active power is equal to the dc component of the
instantaneous power signal p ( t ) in Equation 8, i.e., VI . This is
Figure 52. Combined Gain Response of HPF and Phase Compensation
–0.1
–0.2
–0.3
–0.4
0.4
0.3
0.2
0.1
0.0
t i
v
P
p
p
) (
) (
) (
(
54
t
t
=
t
)
=
=
=
nT
=
1
VI
v
2
2
∫
(
×
0
t
−
×
nT
56
)
I
V
VI
×
p
sin(ω
sin(ω
(
t i
cos(
t
(
)
dt
)
t
2
58
t
)
=
ω
)
FREQUENCY (Hz)
VI
t
)
60
62
64
66
(10)
Rev. B | Page 25 of 56
(7)
(8)
(9)
the relationship used to calculate active power in the ADE7763.
The instantaneous power signal p ( t ) is generated by multiplying
the current and voltage signals. The dc component of the instan-
taneous power signal is then extracted by LPF2 (low-pass filter)
to obtain the active power information. This process is illustrated
in Figure 53.
Because LPF2 does not have an ideal “brick wall” frequency
response (see Figure 54), the active power signal has some
ripple due to the instantaneous power signal. This ripple is
sinusoidal and has a frequency equal to twice the line
frequency. Because the ripple is sinusoidal in nature, it is
removed when the active power signal is integrated to calculate
energy—see the Energy Calculation section.
0xC CCCD
0x19 999A
0x0 0000
–12
–16
–20
–24
–4
–8
0
1
VI
INSTANTANEOUS
POWER SIGNAL
CURRENT
i(t) = 2
Figure 54. Frequency Response of LPF2
Figure 53. Active Power Calculation
3
VOLTAGE
v(t) = 2
×
i
×
sin( ω t)
FREQUENCY (Hz)
×
v
×
p(t) = v
sin( ω t)
10
×
i-v
×
i
×
30
cos(2 ω t)
ACTIVE REAL POWER
SIGNAL = v
ADE7763
×
100
i