Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...

Sensorless Speed Direct Torque Control with Space Vector Modulation (DTC-SVM)
To estimate the initial rotor position before starting DTC-SVM control, two kind of the
rectangular pulsewise voltages are applied from the inverter to the motor:
• one is the short pulsewise voltage,
• and another is the longer one.
Short pulsewise voltage test
This test based on general principle that the three-phase winding inductances of PMSM
are a function of the mechanical rotor position. Therefore, from the line current
responses in stator oriented coordinates α,
β under the short pulse wise voltage (see
Fig. 6.3) the position of PM can be estimated.
Figure 6.3. Voltage pulse wise during short time voltage test.
During the short time (100µ s ) the vector V 1
=(100) and opposite V 4
=(011) is
generated by voltage source inverter. The achieved current responses in α,
β system for
two type of PMSM during this test in respect to mechanical rotor position are presented
in Fig. 6.4.
a) b)
Figure 6.4. Current components in stator oriented coordinates α,
β under supplied voltage
vector to the motor for very short time : a) for Ld = Lq
and b) for Lq > Ld.
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