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參數(shù)資料
| 型號： | ADE7754 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | ADE7754 |
| 中文描述： | ADE7754 |
| 文件頁數(shù)： | 18/44頁 |
| 文件大?。?/td> | 630K |
| 代理商： | ADE7754 |
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REV. PrG 01/03
PRELIMINARY TECHNICAL DATA
ADE7754
–
18
–
Current RMS Gain Adjust
The Active power Gain registers (AAPGAIN[11:0],
BAPGAIN and CAPGAIN) have an effect on the Active
Power and current rms values. It is not recommended to
calibrate the current rms measurements with these registers.
The conversion of the current rms registers values to Am-
peres has to be done in an external Micro-controller with a
specific Ampere/LSB constant for each phase -
see Calibration
of a 3-phase meter based on the ADE7754
. Due to gain
mismatches between phases, the calibration of the Ampere/
LSB constant has to be done for each phase separately. One
point calibration is sufficient for this calibration. The Active
Power Gain registers are aimed to ease the calibration of the
Active energy calculation in MODE 1 and 2 of the VAMODE
register.
If the APGAIN registers are used for Active Power calibra-
tion (WATMOD bits in WATTMode register = 1 or 2), the
current rms values are changed by Active Power Gain register
value as described in the expression below:
Current RMS
phase A
RMS
AAPGAIN
2
12
Register
=
×
+
1
For example, when 7FFh is written to the Active Power Gain
register, the ADC output is scaled up by 22.5%. Similarly,
800h = -2047d (signed 2’s Complement) and ADC output is
scaled by 29.3%. These two examples are illustrated graphi-
cally in Figure 18.
Current RMS offset compensation
The ADE7754 incorporates a current RMS offset compen-
sation for each phase (AIRMSOS, BIRMSOS and
CIRMSOS). These are 12-bit 2-complement signed regis-
ters which can be used to remove offsets in the current RMS
calculations. An offset may exist in the RMS calculation due
to input noises that are integrated in the DC component of
V
2
(t). The offset calibration will allow the contents of the
IRMS registers to be maintained at zero when no current is
being consumed.
n LSB of the Current RMS offset are equivalent to 32768 x
n LSB of the square of the Current RMS register. Assuming
that the maximum value from the Current RMS calculation
is 1,898,124d with full scale AC inputs, then 1 LSB of the
current RMS offset represents 0.0058% of measurement
error at -40dB down of full scale.
I
I
IRMSOS
rms
rms
=
+
×
0
2
32768
where I
rmso
is the RMS measurement without offset correc-
tion.
The current rms offset compensation should be done by
testing the rms results at two non-zero input levels. One
measurement can be done close to full scale and the other at
approximately Full scale/100. The current offset compensa-
tion can then be derived from these measurements -
see
Calibration of a 3-phase meter based on the ADE7754
.
Voltage RMS calculation
Figure 19 shows the details of the signal processing chain for
the RMS calculation on one of the phases of the voltage
channel. The voltage channel RMS value is processed from
the samples used in the voltage channel waveform sampling
mode. The output of the voltage channel ADC can be scaled
by ±50% by changing VGAIN registers to perform an overall
Apparent power calibration -see
Apparent Power calculation.
The VGAIN adjustment affects the RMS calculation as it is
done before the RMS signal processing. The voltage RMS
values are stored in unsigned 24-bit registers (AVRMS,
BVRMS and CVRMS). 256 LSB of the voltage RMS register
is approximately equivalent to one LSB of a voltage wave-
form sample. The update rate of the voltage RMS measurement
is CLKIN/12.
With the specified full scale AC analog input signal of 0.5V,
the LPF1 produces an output code which is approximately
±10,217d at 60 Hz- see
Voltage channel ADC
. The equivalent
RMS value of a full-scale AC signal is approximately 7,221d
(1C35h), which gives a voltage RMS value of 1,848,772
(1C35C4h) in the VRMS register.
With offset calibration, the voltage rms measurement pro-
vided in the ADE7754 is accurate within +/-0.5% for signal
input between Full scale and Full scale/20.
LPF3
Voltage Signal - V(t)
VA
LPF1
S
+
SGN21128
222120
VRMSOS[11:0]
+
800Hex - 7FFHex
12
0.5/GAIN2
FS
Voltage Signal - v(t)
00000h
4000h
28F5h
C000h
D70Ah
+ FS
- FS
ADC Output
word Range
0000h
F1E51Eh
1C35C4h
E1AE2h
+ 100% FS
+ 50% FS
- 100% FS
- 150% FS
E3CA3Ch
D5AF5Ah
+ 150% FS
- 50% FS
2A50A6h
AVGAIN[11:0]
000h
7FFh
800h
Voltage Channel (RMS)
AVGAIN[11:0]
24
Figure 19 - Voltage RMS signal processing
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADE7754AR | ADE7754 |
| ADE7754ARRL | ADE7754 |
| ADE7755AN-REF | Energy Metering IC with Pulse Output |
| ADE7755ARSRL | Energy Metering IC with Pulse Output |
| ADE7755 | Energy Metering IC with Pulse Output |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADE7754AR | 制造商:Analog Devices 功能描述:Energy Measurement 24-Pin SOIC W 制造商:Rochester Electronics LLC 功能描述:THREE PHASE ENERGY METER IC W/WATT & VA - Bulk 制造商:Analog Devices 功能描述:IC ENERGY METER |
| ADE7754ARRL | 制造商:Analog Devices 功能描述:Energy Measurement 24-Pin SOIC W T/R 制造商:Rochester Electronics LLC 功能描述:THREE PHASE ENERGY METER IC W/WATT & VA - Bulk |
| ADE7754ARZ | 功能描述:IC ENERGY METERING 3PHASE 24SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 能量測量 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:* |
| ADE7754ARZRL | 功能描述:IC ENERGY METERING 3PHASE 24SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 能量測量 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:* |
| ADE7755 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Energy Metering IC with Pulse Output |
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