The
function is used for a correct PWM duty cycle output
calculation, based on the measured DC-bus voltage. The side effect is the elimination of
the the DC-bus voltage ripple in the output PWM duty cycle. This function can be used
with any kind of space vector modulation; it has an additional input - the modulation
index (with respect to the DC-bus voltage).
The general equation to calculate the duty cycle is as follows:
Equation 22
where:
• U
PWM
is the duty cycle output
• u
FOC
is the real FOC voltage
• u
dcbus
is the real measured DC-bus voltage
• i
mod
is the space vector modulation index
Using the previous equations, the
function compensates an
amplitude of the direct-
α
and the quadrature-
β
component of the stator-reference voltage
vector, using the formula shown in the following equations:
Equation 23
Equation 24
where:
• U
α
* is the direct-
α
duty cycle ratio
• U
β
* is the direct-
β
duty cycle ratio
• U
α
is the direct-
α
voltage
• U
β
is the quadrature-
β
voltage
If the fractional arithmetic is used, the FOC and DC-bus voltages have their scales, which
take place in
GMCLIB_ElimDcBusRip
GMCLIB User's Guide, Rev. 2, 10/2015
32
Freescale Semiconductor, Inc.
Содержание DSP56800E
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