EVAL-ADE7566F16EB datasheet(57/136 Pages) AD

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Preliminary Technical Data

ADE7566/ADE7569

Rev. PrA | Page 57 of 136

When SAVARM in the ACCMODE Register (0x0F) is set, the

reactive power is accumulated depending on the sign of the

active power. When active power is positive, the reactive power

is added as it is to the reactive energy register. When active

power is negative, the reactive power is subtracted from the

reactive energy accumulator (see the VAR Anti-Tamper

Accumulation Mode section).

When ABSVARM in the ACCMODE Register (0x0F) is set, the

absolute reactive power is used for the reactive energy accumu-

lation (see the VAR Absolute Accumulation Mode section).

The output of the multiplier is divided by VARDIV. If the value

in the VARDIV register is equal to 0, the internal reactive

energy register is divided by 1. VARDIV is an 8-bit, unsigned

accumulated in a 49-bit internal energy accumulation register.

The upper 24 bits of this register are accessible through a read

to the reactive energy register (VARHR[23:0]). A read to the

RVARHR register returns the content of the VARHR register,

and the upper 24 bits of the internal register are cleared.

As shown in Figure 58, the reactive power signal is accumulated

in an internal 49-bit signed register. The reactive power signal

can be read from the waveform register by setting the WAVMODE

voltage channel waveform sampling modes, the waveform date is

available at sample rates of 27.9 kSPS, 14 kSPS, 7 kSPS, or 3.5

kSPS.

Figure 53 shows this energy accumulation for full-scale signals

(sinusoidal) on the analog inputs. These curves also apply for

the reactive energy accumulation

Note that the energy register contents rolls over to full-scale

negative (0x800000) and continues to increase in value when

the power or energy flow is positive. Conversely, if the power is

negative, the energy register underflows to full-scale positive

(0x7FFFFF) and continues to decrease in value.

By using the interrupt enable register, the ADE7569 can be

configured to issue an ADE interrupt to the 8052 core when the

reactive energy register is half-full (positive or negative) or

when an overflow or underflow occurs.

VARGAIN[11:0]

VARDIV[7:0]

LPF2

CURRENT

CHANNEL

VOLTAGE

CHANNEL

TIME (nT)

CLKIN

REACTIVE POWER

SIGNAL

VARHR[23:0]

UPPER 24 BITS ARE

ACCESSIBLE THROUGH

VARHR[23:0] REGISTER

WAVEFORM

VALUES

VAROS[15:0]

sgn

2–6 2–7 2–8

FOR WAVEFORM

SAMPLING

HPF

PHCAL[7:0]

90° PHASE

SHIFTING FILTER

OUTPUTS FROM THE LPF2 ARE

ACCUMULATED (INTEGRATED) IN

THE INTERNAL REACTIVE ENERGY

DIGITAL-TO-FREQUENCY

CONVERTER

Figure 58.. Reactive Energy Calculation

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