MCP3909RD-3PH3 Microchip Technology, MCP3909RD-3PH3 Datasheet - Page 80

• Manufacturer Part Number: MCP3909RD-3PH3
• Description: REF DESIGN FOR MCP3909 W/18F2520
• Manufacturer: Microchip Technology

Specifications of MCP3909RD-3PH3

• Main Purpose: Power Management, Energy/Power Meter
• Utilized Ic / Part: MCP3909, PIC18F2520, PIC18F4550
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

MCP3909 / dsPIC33F 3-Phase Energy Meter Reference Design
DS51723A-page 80
N-th iteration:
Where ρ
Complex rectangular quadrature algorithm or complex trapezoidal quadrature
algorithm is usually used in quasi-synchronous sampling.
Figure C-2 shows a 3-cycle interative process.
FIGURE C-2:
In practical applicatons, a frequency offset Δ is usually small, and good results may
usually be obtained through 3-5 iterations.
As mentioned above, the iterative process will result in a group of weight coefficients
η
from the numeric quadrature formula. The relationship between the iterative result and
original data is shown in Equation C-9.
EQUATION C-9:
i
, called weight coefficients of quasi-synchronous algorithm, they may be deduced
Original data
First Iteration
Second Iteration
Third Iteration
i
is the weight coefficient which is decided by the digital quadrature formula.
F
F
F
f
0
0
0
3-Cycle Iterative Process.
0
1
2
3
F
F
f
1
1
1
1
2
F
f
F
2
2
F
1
2
F
2
0
0
n
......
n
...... F
...... F
=
=
=
=
-------------- -
i
--------------- -
n
i
∑
----- -
N
=
∑
N
1
f
=
×
N
N
n
i
1
n
N
0
1
∑
1
N
=
0
×
2
⋅
ρ
η
N
n
F
i
0
i
∑
f
i
=
R
⋅
×
N+1
1
⋅
N+1
i
N
i
0
∑
n
i
=
N
⋅
∑
η
=
×
f x
0
i
( )
N
0
ρ
F
⋅
f
η
i
1
f x
i
N+2
( )
N+2
⋅
i
⋅
F
i
f x
i
( )
n 1
–
......
...... F
i
f
1
2N
2N
© 2009 Microchip Technology Inc.
f
2N+1
f
2N+2
......
f
3N