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Embedded Software and Motor Control Libraries for PXR40xx

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Function GMCLIB_SvmStd_F16<br />

The quantities of the direct-u α <strong>and</strong> the quadrature-u β components of the two-phase<br />

orthogonal coordinate system, describing the three-phase stator voltages, are expressed<br />

by the Clarke Trans<strong>for</strong>mation.<br />

Equation GMCLIB_SvmStd_Eq1<br />

Equation GMCLIB_SvmStd_Eq2<br />

The three-phase stator voltages,U a, U b, <strong>and</strong> U c, are trans<strong>for</strong>med using the Clarke<br />

Trans<strong>for</strong>mation into the U α <strong>and</strong> the U β components of the two-phase orthogonal<br />

coordinate system. The trans<strong>for</strong>mation results are listed in Table 4-144.<br />

Table 4-144. Switching patterns <strong>and</strong> space vectors<br />

a b c u α u β Vector<br />

0 0 0 0 0 O 000<br />

1 0 0 2/3*U DCBus 0 U 0<br />

1 1 0 1/3*U DCBus 1/ √(3)*U DCBus U 60<br />

0 1 0 -1/3*U DCBus 1/ √(3)*U DCBus U 120<br />

0 1 1 -2/3*U DCBus 0 U 240<br />

0 0 1 -1/3*U DCBus -1/ √(3)*U DCBus U 300<br />

1 0 1 1/3*U DCBus -1/ √(3)*U DCBus U 360<br />

1 1 1 0 0 O 111<br />

Figure 4-60 graphically depicts some feasible basic switching states (vectors). It is clear<br />

that there are six non-zero vectors U 0, U 60, U 120, U 240. U 300, <strong>and</strong> two zero vectors O<br />

111, O 000, usable <strong>for</strong> switching. There<strong>for</strong>e, the principle of the St<strong>and</strong>ard Space Vector<br />

Modulation resides in applying appropriate switching states <strong>for</strong> a certain time <strong>and</strong> thus<br />

generating a voltage vector identical to the reference one.<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 />

516 Freescale Semiconductor, Inc.

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