Analog Devices ADE9000, Техническое справочное руководство

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UG-1098 ADE9000 Technical Reference Manual
Rev. 0 | Page 18 of 86
ENERGY ACCUMULATION
NO LOAD
CHECK
0
INTERNAL ENERGY
ACCUMULATOR
41 31
CFx
DIGITAL
TO
FREQUENCY
CONVERTER
4.096MHz
AWATT
WATTACC[1:0]
ACT_NL_LVL
+
+
0
CHECK SIGN
TO DETERMINE
WHETHER
TO ACCUMULATE
0
ANOLOAD
EP_CFG.
NOLOAD_TMR
1
WTHR
CF1DEN
CF_LCFG
CFMODE
REVPSUMx
CFx
POWER
ENERGY
LOW-PASS
FILTERED
TOTAL ACTIVE
POWER
0
INTERNAL POWER ACCUMULATOR
41 31
+
+
f
DSP
EGYRDY
31 0 0 31
AWATTHR_HI
12
+
+
0
0
1
EGY_LD_ACCUM
INTERNAL ENERGY ACCUMULATOR
VALUE ADDED TO AWATTHR
OR LATCHED INTO AWATTHR
AT EGYRDY RATE
PWRRDY
INTERNAL POWER ACCUMULATOR VALUE
LATCHED IN TO AWATT_ACC
WHEN PWR_TIMER SAMPLES
HAVE BEEN ACCUMULATED
31 0
AWATT_ACC
f
DSP
AWATTHR_LO
12 13
15523-
021
Figure 21. AWATT Accumulation into Energy and Power, Using No-load Threshold and Signed Accumulation Mode
Figure 21 shows how AWATT is accumulated into the AWATTHR
and AWATT_ACC registers. A no-load threshold is applied and
the energy is checked to determine whether to accumulate the
AWATT sample into the internal energy accumulator.
The internal energy accumulator is either added to the
AWATTHR register or overwrites it at a EGYRDY rate. Set the
EGY_PWR_EN bit in EP_CFG register to run the energy and
power accumulator.
Signed Energy Accumulation Modes
Total Active Energy Accumulation Modes
In some installations, it is desirable to bill for only positive total
active energy. The
ADE9000 offers a way to do this using the
WATTACC[1:0] bits in the ACCMODE register. To set the
total and fundamental active energy accumulation and any
corresponding CF pulse output for positive energy only, write
WATTACC[1:0] to 10.
If WATTACC[1:0] is equal to zero, the energy accumulation is
signed. The MSB of the AWATTHR_HI and AFWATTHR_HI
registers indicates whether the accumulated energy is negative
or positive.
Other accumulation modes include absolute accumulation mode
with WATTACC[1:0] equal to 01 (where the absolute value of
AWATT is accumulated), and negative only accumulation mode
with WATTACC[1:0] equal to 11 (where only negative active
energy is accumulated).
Reactive Energy Accumulation Modes
In some installations, because reactive energy can change
frequently between positive and negative values with inductive
and capacitive loads, it is desirable to bill for the absolute value
of reactive energy. The
ADE9000 offers a way to do this using
the VARACC[1:0] bits in the ACCMODE register. To set the
total and fundamental reactive energy register and any
corresponding CF pulse output to accumulate the absolute
value of reactive energy, write VARACC[1:0] to 01.
If VARACC[1:0] is equal to zero, the total and fundamental
reactive energy accumulation is signed. The MSB of the