ADE7166_15 datasheet(64/152 Pages) AD

64 / 152 page

ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/ADE7569

Rev. B | Page 64 of

152

ACTIVE ENERGY CALCULATION

As stated in the Active Power Calculation section, power is

defined as the rate of energy flow. This relationship can be

expressed mathematically, as shown in Equation 13.

(13)

where:

P is power.

E is energy.

Conversely, energy is given as the integral of power.

∫

)

(

(14)

The ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/

ADE7569 achieve the integration of the active power signal by

continuously accumulating the active power signal in an

internal, nonreadable, 49-bit energy register. The register

(WATTHR[23:0], Address 0x01) represents the upper 24 bits

of this internal register. This discrete time accumulation or

summation is equivalent to integration in continuous time.

Equation 15 expresses the relationship.

⎭

⎬

⎫

⎩

⎨

⎧

∑

∫

∞

→

)

(

lim

)

(

(15)

where:

n is the discrete time sample number.

T is the sample period.

The discrete time sample period (T) for the accumulation

ADE7566/ADE7569 is 1.22 μs (5/MCLK). In addition to

calculating the energy, this integration removes any sinusoidal

components that may be in the active power signal. Figure 66

shows this discrete time integration or accumulation. The active

power signal in the waveform register is continuously added to

the internal active energy register.

The active energy accumulation depends on the setting of

POAM (Bit 1) and ABSAM (Bit 0) in the ACCMODE register

(Address 0x0F). When both bits are cleared, the addition is

signed and, therefore, negative energy is subtracted from the

active energy contents. When both bits are set, the ADE7166/

ADE7169/ADE7566/ADE7569 are set to be in the more

restrictive mode, the positive-only accumulation mode.

When POAM (Bit 1) in the ACCMODE register (Address 0x0F)

is set, only positive power contributes to the active energy

accumulation. When ABSAM (Bit 0) in the ACCMODE

for the active energy accumulation (see the Watt-Absolute

Accumulation Mode section).

The output of the multiplier is divided by the value in the WDIV

equal to 0, the internal active energy register is divided by 1.

WDIV is an 8-bit, unsigned register. After dividing by WDIV,

the active energy is accumulated in a 49-bit internal energy

accumulation register. The upper 24 bits of this register are

accessible through a read to the active energy register

(WATTHR[23:0], Address 0x01). A read to the RWATTHR

As shown in Figure 66, the active power signal is accumulated

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

be read from the waveform register by setting the WAVMODE

Interrupt Enable 3 SFR (MIRQENH, Address 0xDB). Like the

current and voltage channels waveform sampling modes, the

waveform data is available at sample rates of 25.6 kSPS, 12.8 kSPS,

6.4 kSPS, and 3.2 kSPS.

WGAIN[11:0]

WDIV[7:0]

LPF2

CURRENT

CHANNEL

VOLTAGE

CHANNEL

TIME (nT)

CLKIN

ACTIVE POWER

SIGNAL

WATTHR[23:0]

OUTPUTS FROM THE LPF2 ARE

ACCUMULATED (INTEGRATED) IN

THE INTERNAL ACTIVE ENERGY REGISTER

UPPER 24 BITS ARE

ACCESSIBLE THROUGH

WATTHR[23:0] REGISTER

WATTOS[15:0]

sgn

2–6 2–7 2–8

FOR WAVEFORM

SAMPLING

DIGITAL-TO-FREQUENCY

CONVERTER

WAVEFORM

VALUES

Figure 66. Active Energy Calculation

ADE7166 数据表(PDF) 64 Page - Analog Devices

ADE7166 数据表(HTML) 64 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载