CSA output has an offset induced due
to ground differences between the sense FET and output FET. When running trapezoidal
control or another single-shunt based control (sensored sine, for example) this CSA
offset has no impact to operation. When running sensorless sinusoidal or FOC control
where two or three current sense are required, some current distortion and noise may
occur unless the user implements the corrective action below.
Corrective Action: Implement
the below equations in firmware to correct for any current induced offset:
- When all three current sense
amplifiers are used:
Equation 5.
Equation 6.
Equation 7.
- When only two of the three
current sense amplifiers are used:
- Current sensed in phases
A & B:
Equation 8.
Equation 9.
Equation 10.
- Current sensed in phases
B & C:
Equation 11.
Equation 12.
Equation 13.
- Current sensed in phases
C & A:
Equation 14.
Equation 15.
Equation 16.