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Embedded Software and Motor Control Libraries for PXR40xx

Embedded Software and Motor Control Libraries for PXR40xx

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Function GFLIB_<strong>Control</strong>lerPIp_F16<br />

The fractional representation of both input <strong>and</strong> output signals, normalized between [-1,<br />

1), is obtained as follows:<br />

Equation GFLIB_<strong>Control</strong>lerPIp_Eq5<br />

Equation GFLIB_<strong>Control</strong>lerPIp_Eq6<br />

Applying such scaling (normalization) on the proportional term of equation<br />

GFLIB_<strong>Control</strong>lerPIp_Eq3 results in:<br />

Equation GFLIB_<strong>Control</strong>lerPIp_Eq7<br />

where K P_sc is the proportional gain parameter considering input/output scaling.<br />

Analogically, scaling the integral term of equation GFLIB_<strong>Control</strong>lerPIp_Eq4 results in:<br />

Equation GFLIB_<strong>Control</strong>lerPIp_Eq8<br />

where K I_sc is the integral gain parameter considering input/output scaling.<br />

The sum of the scaled proportional <strong>and</strong> integral terms gives a complete equation of the<br />

controller:<br />

Equation GFLIB_<strong>Control</strong>lerPIp_Eq9<br />

The problem is however, that either of the gain parameters K P_sc, K I_sc can be out of the<br />

[-1, 1) range, hence cannot be directly interpreted as fractional values. To overcome this,<br />

it is necessary to scale these gain parameters using the shift values as follows:<br />

<strong>Embedded</strong> <strong>Software</strong> <strong>and</strong> <strong>Motor</strong> <strong>Control</strong> <strong>Libraries</strong> <strong>for</strong> <strong>PXR40xx</strong>, Rev. 1.0<br />

274 Freescale Semiconductor, Inc.

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