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