ADE7763 View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'ADE7763' PDF : 56 Pages View PDF
ADE7763
CURRENT
CHANNEL
VOLTAGE
CHANNEL
LPF2
APOS[15:0]
++
WDIV[7:0]
UPPER 24 BITS ARE
ACCESSIBLE THROUGH
AENERGY[23:0]
AENERGY[23:0] REGISTER
23
0
%
WGAIN[11:0]
48
0
ACTIVE POWER
SIGNAL
T
4
CLKIN
WAVEFORM
REGISTER
VALUES
OUTPUTS FROM THE LPF2 ARE
ACCUMULATED (INTEGRATED) IN
THE INTERNAL ACTIVE ENERGY REGISTER
TIME (nT)
Figure 55. Active Energy Calculation
Figure 55 shows the signal processing chain for the active power
calculation. The active power is calculated by low-pass filtering
the instantaneous power signal. Note that when reading the
waveform samples from the output of LPF2, the gain of the
active energy can be adjusted by using the multiplier and watt
gain register (WGAIN[11:0]). The gain is adjusted by writing a
twos complement 12-bit word to the watt gain register.
Equation 11 shows how the gain adjustment is related to the
contents of the watt gain register:
Output
WGAIN
=
⎜⎜⎝⎛
Active
Power
×
⎨⎧1 +
⎩
WGAIN
212
⎫
⎬
⎭
⎟⎟⎠⎞
(11)
For example, when 0x7FF is written to the watt gain register, the
power output is scaled up by 50%. 0x7FF = 2047d, 2047/212 = 0.5.
Similarly, 0x800 = –2048d (signed twos complement) and
power output is scaled by –50%. Each LSB scales the power
output by 0.0244%. Figure 56 shows the maximum code
(hexadecimal) output range for the active power signal (LPF2).
Note that the output range changes depending on the contents
of the watt gain register. The minimum output range is given
when the watt gain register contents are equal to 0x800, and the
maximum range is given by writing 0x7FF to the watt gain
register. This can be used to calibrate the active power (or
energy) calculation.
0x1 3333
0xCCCD
0x6666
0x0 0000
0xF 999A
0xF 3333
0xE CCCD
0x000 0x7FF 0x800
{WGAIN[11:0]}
ACTIVE POWER
CALIBRATION RANGE
POSITIVE
POWER
NEGATIVE
POWER
Figure 56. Active Power Calculation Output Range
ENERGY CALCULATION
As stated earlier, power is defined as the rate of energy flow.
This relationship is expressed mathematically in Equation 12.
P = dE
(12)
dt
where:
P is power.
E is energy.
Conversely, energy is given as the integral of power.
∫ E = Pdt
(13)
Rev. A | Page 26 of 56
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