Embedded Software and Motor Control Libraries for PXR40xx

Function GMCLIB_ElimDcBusRip_F16
The f16ModIndex and f16ArgDcBusMsr are supplied to the function within the
parameters structure through its members. The u α, u β correspond respectively to the
f16Arg1 and f16Arg2 members of the input structure, and the u α* and u β* respectively
to the f16Arg1 and f16Arg2 members of the output structure.
It should be noted that although the modulation index (see the parameters structure, the
f16ModIndex member) is assumed to be equal to or greater than zero, the possible values
are restricted to those values resulting from the use of Space Vector Modulation
techniques.
In order to correctly handle the discontinuity at f16ArgDcBusMsr approaching 0, and for
efficiency reasons, the function will assign 0 to the output duty cycle ratios if the
f16ArgDcBusMsr is below the threshold of 2 -15 . In other words, the 16 least significant
bits of the f16DcBusMsr are ignored. Also, the computed output of the and u β*
components may have an inaccuracy in the 16 least significant bits.
Note
Both the inverse modulation index pIn->f16ModIndex and the
measured DC bus voltage pIn->f16DcBusMsr must be equal to
or greater than 0, otherwise the results are undefined.
4.104.5 Re-entrancy
The function is re-entrant.
4.104.6 Code Example
#include "gmclib.h"
#define U_MAX (36.0) // voltage scale
SWLIBS_2Syst_F16 f16AB;
SWLIBS_2Syst_F16 f16OutAB;
GMCLIB_ELIMDCBUSRIP_T_F16 f16trMyElimDcBusRip =
GMCLIB_ELIMDCBUSRIP_DEFAULT_F16;
~ 0x7FFF
void main(void)
{
// inverse modulation coefficient for standard space vector modulation
f16trMyElimDcBusRip.f16ModIndex = FRAC16 (0.866025403784439);
// Input voltage vector 15V @ angle 30deg
// alpha component of input voltage vector = 12.99[V]
f16AB.f16Arg1 = FRAC16 (12.99/U_MAX);
// beta component of input voltage vector = 7.5[V]
f16AB.f16Arg2 = FRAC16 (7.5/U_MAX);
// value of the measured DC bus voltage 17[V]
f16trMyElimDcBusRip.f16ArgDcBusMsr = FRAC16 (17.0/U_MAX);
// output alpha component of the output vector should be
// f16OutAB.f16Arg1 = (12.99/36)*0.8660/(17.0/36/2) = 1.3235 -> FRAC16(1.0)
Embedded Software and Motor Control Libraries for PXR40xx, Rev. 1.0
482 Freescale Semiconductor, Inc.