SDAA502 Application note

SDAA502 August 2026 TMCS2100-Q1

2.3.1.3 Combined-Field Amplitude Under Balanced Operation

For balanced three-phase currents with amplitude I₀, the combined-field sensitivity at each sensor is calculated from the measured component sensitivities as follows.

Phase A:

Equation 5.

S_{T o t a l, A} = \frac{|V_{A}|}{I_{0}} = \sqrt{{(S_{A A} - \frac{1}{2} S_{A B} - \frac{1}{2} S_{A C})}^{2} + \frac{3}{4} {(S_{A B} - S_{A C})}^{2}}

Phase B:

Equation 6.

S_{T o t a l, B} = \frac{|V_{B}|}{I_{0}} = \sqrt{{(S_{B B} - \frac{1}{2} S_{B A} - \frac{1}{2} S_{B C})}^{2} + \frac{3}{4} {(S_{B A} - S_{B C})}^{2}}

Phase C:

Equation 7.

S_{T o t a l, C} = \frac{|V_{C}|}{I_{0}} = \sqrt{{(S_{C C} - \frac{1}{2} S_{C A} - \frac{1}{2} S_{C B})}^{2} + \frac{3}{4} {(S_{C A} - S_{C B})}^{2}}

Note: Derivation note: These expressions result from phasor addition of the three sinusoidal components.

The amplitude error for phase X is:

Equation 8.

{E r r o r}_{X} (%) = \frac{S_{T o t a l, X} - S_{i d e a l, X}}{S_{i d e a l, X}} \times 100

Where S_ideal,X (in V/A) is the ideal sensitivity for phase X.