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Embedded Software and Motor Control Libraries for PXR40xx

Embedded Software and Motor Control Libraries for PXR40xx

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available DC bus voltage. There<strong>for</strong>e, any variations in amplitude of the actual DC bus<br />

voltage must be accounted <strong>for</strong> by modifying the amplitude of the required voltage so that<br />

the output phase voltage remains unaffected.<br />

For a better underst<strong>and</strong>ing, let's consider the following two simple examples:<br />

Example 1:<br />

• amplitude of the required phase voltage U reg=50[V]<br />

• maximal amplitude of the DC bus voltage U DC_BUS_MAX=100[V]<br />

• actual amplitude of the DC bus voltage DC_BUS_ACTUAL[V]<br />

• voltage to be applied to the PWM modulator to generate U reg=50[V] on the inverter<br />

phase output:<br />

Equation GMCLIB_ElimDcBusRip_Eq1<br />

Example 2:<br />

• amplitude of the required phase voltage U reg=50[V]<br />

• maximal amplitude of the DC bus voltage U DC_BUS_MAX=100[V]<br />

• actual amplitude of the DC bus voltage U DC_BUS_ACTUAL=90[V]<br />

• voltage to be applied to the PWM modulator to generate U reg=50[V] on the inverter<br />

phase output:<br />

Equation GMCLIB_ElimDcBusRip_Eq2<br />

The imperfections of the DC bus voltage are compensated <strong>for</strong> by the modification of<br />

amplitudes of the direct- α <strong>and</strong> the quadrature- β components of the stator reference<br />

voltage vector. The following <strong>for</strong>mulas are used:<br />

• <strong>for</strong> the α-component:<br />

• <strong>for</strong> the β-component:<br />

Equation GMCLIB_ElimDcBusRip_Eq3<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 />

Chapter 4 API References<br />

Freescale Semiconductor, Inc. 477

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