AN1931D Freescale Semiconductor / Motorola, AN1931D Datasheet - Page 40

• Manufacturer Part Number: AN1931D
• Description: 3-Phase PM Synchronous Motor Vector Control
• Manufacturer: Freescale Semiconductor / Motorola

Software Design
6.2.5.2 Speed Ramp
6.2.5.3 Speed, Alignment Control Process
6.2.5.4 Field-Weakening Process
40
The u_SDQ voltages are transformed into u_SAlphaBeta
Transformation process. The Scaling DCBus Ripple Compensation block scales u_SAlphaBeta
(according u_dc_bus_filt) to u_Salpha_RipElim, described in the svmlimDcBusRip function in the
Motor Control Library. The space vector modulation process generates duty cycle pwmABC and
svmSector according to u_Salpha_RipElim.
The u_LimitF16 is a voltage limit for current controllers. The u_OverMax constant is used to increase
the limitation of u_SDQ voltages over maximum SVM_INV_INDEX/2*u_dc_bus_filt determined by
the DCBus voltage and space vector modulation. Although the pwmABC will be limited by the space
vector modulation process functions, the reserve is used for field-weakening controller dynamics. In
the stable state, the u_SDQ voltages vector will not exceed u_S_max_FWLimit; see
The process generates angular speed omega_desired_mech from angular speed omega_required_mech
with a linear ramp. The speed ramp is implemented so as not to saturate the speed regulator during
acceleration.
The process controls the i_SDQ_desired.q_axis current according to the PMSM Control Process
Status.
For Alignment status, it sets i_SDQ_desired.d_axis to i_Sd_Alignment and i_SDQ_desired.q_axis to 0.
For Run status, it controls the omega_actual_mech speed to omega_desired_mech by calculation of
the PI regulator with i_SDQ_desired.q_axis output.
The field-weakening process provides control of i_SDQ_desired.d_axis in order to achieve higher
motor speeds by the field-weakening technique. The control algorithm is shown in
u_S_max_FWLimit is computed from u_dc_bus_filt. The u_Reserve_FW is subtracted, in order to have
some voltage reserve, to the maximum SVM_INV_INDEX/2*u_dc_bus_filt determined by DCBus
voltage and space vector modulation. The reserve is used for field-weakening controller dynamics; in
the stable state, the u_SDQ voltages vector will not exceed u_S_max_FWLimit.
u_SD.d_axis
u_SD.q_axis
(
d_axis
u_dc_bus_filt
2
SVM_INV_INDEX/2*u_dc_bus_filt-u_Reserve_FW
+
q_axis
Freescale Semiconductor, Inc.
3-Phase PM Synchronous Motor Vector Control
Figure 6-8. Field-Weakening Controller
For More Information On This Product,
2
)
1/2
u_S_max_FWLimit
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SVM_INV_INDEX
-
+
max limit
u_Reserve_FW
0
PI regulator
-
I_SDQ_MAX_F16
(see
min limit
Section
3.3.3) by the Voltage
i_SDQ_desired.d_axis
Section
Figure
MOTOROLA
6.2.5.4.
6-8. The