ADE7758 Analog Devices, ADE7758 Datasheet - Page 25

• Manufacturer Part Number: ADE7758
• Description: Poly Phase Multifunction Energy Metering IC with Per Phase Information
• Manufacturer: Analog Devices

The phase calibration registers (APHCAL, BPHCAL, and
CPHCAL) are twos complement, 7-bit signed registers that can
vary the time advance/delay in the voltage channel signal path
from –151.2 µs to +75.6 µs (CLKIN = 10 MHz). One LSB is
equivalent to 1.2 µs of time delay or 2.4 µs of time advance.
With a line frequency of 50 Hz, this gives a phase resolution of
0.026° at the fundamental, i.e., 360° × 1.2 µs × 60 Hz, in the positive
direction and 0.052° in the negative direction. This corresponds to
a total correction range of −2.72° to +1.36° at 50 Hz.
Figure 56 illustrates how the phase compensation is used to
remove a 0.1° phase lead in IA of the current channel from the
external current transducer. In order to cancel the lead (0.1°) in
the current channel of Phase A, a phase lead must be introduced
into the corresponding voltage channel. The resolution of the
phase adjustment allows the introduction of a phase lead of
0.104°. The phase lead is achieved by introducing a time advance
into VA. A time advance of −4.8 µs is made by writing −4 (0x3C)
to the time delay block (APHCAL[7:0]), thus reducing the
amount of time delay by 4.8 µs or equivalently, 360° × 4.8 µs ×
60 Hz = 0.104° at 60 Hz.
Figure 53. Phase Response of the HPF and Phase Compensation
90
80
70
60
50
40
30
20
10
0
0
100
200
300
(10 Hz to 1 kHz)
IA
VA
FREQUENCY (Hz)
400
IAN
VN
IAP
VAP
V2
500
PGA1
PGA2
V1
600
60Hz
700
0.1°
ADC
ADC
800
Figure 56. Phase Calibration on Voltage Channels
900
+1.36°, –2.72° @ 50Hz; 0.022°, 0.043°
+1.63°, –3.28° @ 60Hz; 0.026°, 0.052°
1k
6
–151.2µs TO +75.6µs
HPF
RANGE OF PHASE
1 1 1 1 1 0 0
CALIBRATION
APHCAL[6:0]
Rev. A | Page 25 of 68
INTEGRATOR
DIGITAL
0
Figure 54. Phase Response of the HPF and Phase Compensation
–0.05
–0.10
–0.02
0.20
0.15
0.10
0.05
0.10
0.08
0.06
0.04
0.02
Figure 55. Gain Response of HPF and Phase Compensation
0
0
40
44
VA
CALCULATION
45
46
ACTIVE AND
REACTIVE
60Hz
IA
ENERGY
VA DELAYED BY 4.8
(–0.104
50
48
(40 Hz to 70 Hz)
(44 Hz to 56 Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
0x7C
°
@ 60Hz)
55
50
µ
s
60
52
65
54
ADE7758
70
56