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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 GMCLIB_ElimDcBusRip_F16<br />

4.104.2 Arguments<br />

Table 4-129. GMCLIB_ElimDcBusRip_F16 arguments<br />

Type Name Direction Description<br />

SWLIBS_2Syst_F16<br />

*const<br />

const<br />

SWLIBS_2Syst_F16<br />

*const<br />

const<br />

GMCLIB_ELIMDCBUS<br />

RIP_T_F16 *const<br />

4.104.3 Return<br />

Function returns no value.<br />

4.104.4 Description<br />

pOut output Pointer to the structure with direct ( α) <strong>and</strong> quadrature ( β)<br />

components of the required stator voltage vector re-calculated<br />

so as to compensate <strong>for</strong> voltage ripples on the DC bus.<br />

pIn input Pointer to the structure with direct ( α) <strong>and</strong> quadrature ( β)<br />

components of the required stator voltage vector be<strong>for</strong>e<br />

compensation of voltage ripples on the DC bus.<br />

pParam input Pointer to the parameters structure.<br />

The GMCLIB_ElimDcBusRip function provides a computational method <strong>for</strong> the<br />

recalculation of the direct ( α) <strong>and</strong> quadrature ( β) components of the required stator<br />

voltage vector, so as to compensate <strong>for</strong> voltage ripples on the DC bus of the power stage.<br />

Considering a cascaded type structure of the control system in a st<strong>and</strong>ard motor control<br />

application, the required voltage vector to be applied on motor terminals is generated by a<br />

set of controllers (usually P, PI or PID) only with knowledge of the maximal value of the<br />

DC bus voltage. The amplitude <strong>and</strong> phase of the required voltage vector are then used by<br />

the pulse width modulator (PWM) <strong>for</strong> generation of appropriate duty-cycles <strong>for</strong> the<br />

power inverter switches. Obviously, the amplitude of the generated phase voltage<br />

(averaged across one switching period) does not only depend on the actual on/off times of<br />

the given phase switches <strong>and</strong> the maximal value of the DC bus voltage. The actual<br />

amplitude of the phase voltage is also directly affected by the actual value of the<br />

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 />

<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 />

480 Freescale Semiconductor, Inc.

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