STPMC1 datasheet(45/77 Pages) STMICROELECTRONICS

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STPMC1

Theory of operation

Doc ID 15728 Rev 6

45/77

An asymmetrical compensation is implemented by multiplying the phase current with

α and

the neutral current with

β and these values are subtracted from neutral and phase currents

respectively, as shown below:

iCS = β iT

iCT = α iS

For other values of SYS, the values of CCA and CCB three correction factors, a 7-bit

α, 6-bit

β and 4-bit γ (gamma) are calculated as follows:

Equation 7

Equation 8

Equation 9

From these factors a 4 x 4 matrix, shown in

Table 30, implements a symmetrical

compensation multiplying each phase and neutral current with its row, adding the products

together and subtracting them from the currents.

iCR = α iS + β iT + γ iN

iCS = α iR + α iT + β iN

Table 29.

Mutual current compensation matrix for single-phase systems (SYS > 3)

phase

S-

(

± 0.78 %)

() []

[]

8192

CCA

⋅

−

(

± 0.39 %)

() []

[]

8192

CCB

CCA

⋅

−

(

± 0.09 %)

() []

[]

8192

CCB

CCA

⋅

−

Table 30.

Mutual current compensation matrix for three-phase systems (SYS < 4)

phase

αβ

βα

γβ

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