MCP3909RD-3PH3 Microchip Technology, MCP3909RD-3PH3 Datasheet - Page 94

• 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
C.12 HARMONIC COMPONENTS OF CURRENT, VOLTAGE AND TOTAL
DS51723A-page 94
HARMONIC DISTORTION
In Section C.3 “The Harmonic Analysis Algorithm Of Quasi-synchronous Sam-
pling”, we discussed the measuring of current and voltage signals for each order of
harmonics. 3 parameters are used to show to what extent a distorted wave deviates
from a sine wave. They are: harmonic content, total distortion and harmonic ratio of the
k-th harmonic. The term harmonic content means the root of square of effective values
for all harmonics, which is defined as:
EQUATION C-60:
The total voltage distortion ratio of harmonics is the ratio of harmonic content to the
fundamental in percentage, which is defined as:
EQUATION C-61:
The k-th harmonic ratio for voltage is the ratio of the k-th harmonic to the fundamental
in percentage, defined as:
EQUATION C-62:
Similarly, harmonics of each order for the current and total distortion ratio can be sorted
out.
THD
U
=
THD
U
-------
U
U
H
H
I
Uk
×
=
100%
=
k
U
------
U
∑
N
=
1
k
2
×
k
U
∑
100%
N
=
k
2
2
(
THD
Uk
)
© 2009 Microchip Technology Inc.
2